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Test-Retest and Inter-Rater Reliability for Selected Outcomes from a Wearable 3D Inertial Sensor over Different Stable and Unstable Postural Conditions: A Validation Study

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Title: Test-Retest and Inter-Rater Reliability for Selected Outcomes from a Wearable 3D Inertial Sensor over Different Stable and Unstable Postural Conditions: A Validation Study
Language: English
Authors: Samuel D'Emanuele (ORCID 0000-0001-6232-9870), Francesca Nardello (ORCID 0000-0001-8942-3920), Fabrizio Garau (ORCID 0009-0007-1564-2347), Diego Campaci (ORCID 0009-0008-4238-2146), Federico Schena (ORCID 0000-0002-2052-5117), Cantor Tarperi (ORCID 0000-0002-7208-9484)
Source: Measurement in Physical Education and Exercise Science. 2025 29(1):98-112.
Availability: Routledge. Available from: Taylor & Francis, Ltd. 530 Walnut Street Suite 850, Philadelphia, PA 19106. Tel: 800-354-1420; Tel: 215-625-8900; Fax: 215-207-0050; Web site: http://www.tandf.co.uk/journals
Peer Reviewed: Y
Page Count: 15
Publication Date: 2025
Document Type: Journal Articles
Reports - Research
Descriptors: Human Posture, Measurement Equipment, Interrater Reliability, Measurement Techniques, Young Adults, Test Reliability, Validity, Foreign Countries
Geographic Terms: Italy
DOI: 10.1080/1091367X.2024.2403564
ISSN: 1091-367X
1532-7841
Abstract: The agreement between a wearable inertial sensor (GYKO, G) and the force platform (P) was assessed by evaluating "test-retest" and "inter-rater reliability." Thirty-eight subjects were enrolled; the selected indices of balance were investigated over foot positions and (un)stable conditions. Intraclass correlation coefficient (ICC), standard error of measurement (SEM[subscript %]) and minimal detectable change (MDC[subscript95%]) were computed. For G, ICC bounds range from "poor" to "excellent" (0.040 ÷ 0.921), mean of 0.687 (= "moderate reliability"). Regarding P, ICC ranges from "poor" to "excellent" (0.070 ÷ 0.920), mean of 0.683 (= "moderate reliability"). For G, SEM[subscript %] ranges from 11% to 47%; MDC[subscript95%] from 30% to 132%. Concerning P, SEM[subscript %] ranges from 7% to 41%; MDC[subscript95%] from 21% to 114%. Finally, the "inter-rater reliability" ICC by comparing devices ranges from "poor" to "excellent" (-0.162 ÷ 0.911), mean of 0.338 (= "poor reliability"). GYKO appears to be a convenient tool with high consistency among multiple measurements but for specific clinic/research purposes.
Abstractor: As Provided
Entry Date: 2025
Accession Number: EJ1458853
Database: ERIC
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  Value: <anid>AN0182438457;7mm01jan.25;2025Jan28.02:47;v2.2.500</anid> <title id="AN0182438457-1">Test-Retest and Inter-Rater Reliability for Selected Outcomes from a Wearable 3D Inertial Sensor Over Different Stable and Unstable Postural Conditions: A Validation Study </title> <p>The agreement between a wearable inertial sensor (GYKO, G) and the force platform (P) was assessed by evaluating test-retest and inter-rater reliability. Thirty-eight subjects were enrolled; the selected indices of balance were investigated over foot positions and (un)stable conditions. Intraclass correlation coefficient (ICC), standard error of measurement (SEM<sub>%</sub>) and minimal detectable change (MDC<sub>95%</sub>) were computed. For G, ICC bounds range from poor to excellent (0.040 ÷ 0.921), mean of 0.687 (= moderate reliability). Regarding P, ICC ranges from poor to excellent (0.070 ÷ 0.920), mean of 0.683 (= moderate reliability). For G, SEM<sub>%</sub> ranges from 11% to 47%; MDC<sub>95%</sub> from 30% to 132%. Concerning P, SEM<sub>%</sub> ranges from 7% to 41%; MDC<sub>95%</sub> from 21% to 114%. Finally, the inter-rater reliability ICC by comparing devices ranges from poor to excellent (−0.162 ÷ 0.911), mean of 0.338 (= poor reliability). GYKO appears to be a convenient tool with high consistency among multiple measurements but for specific clinic/research purposes.</p> <p>Keywords: Balance; Accelerometer; Force platform; Agreement; Consistency</p> <hd id="AN0182438457-2">Introduction</hd> <p>Posturography assessment, within the clinical domain, serves to estimate the risk of falls in geriatric individuals (Piirtola & Era, [<reflink idref="bib31" id="ref1">31</reflink>]) and to assess balance-related impairments, such as those associated with Parkinson's disease, concussion, and stroke, as well as rehabilitation protocols (Agostini et al., [<reflink idref="bib1" id="ref2">1</reflink>], [<reflink idref="bib3" id="ref3">3</reflink>]; Maranesi et al., [<reflink idref="bib23" id="ref4">23</reflink>]). In the context of sports science, posturography is utilized to discern subtle variations in the balanced performances of athletes (Agostini et al., [<reflink idref="bib2" id="ref5">2</reflink>]; Davlin, [<reflink idref="bib9" id="ref6">9</reflink>]). The growing interest in the study of balance has prompted a continuous evolution of the methods employed in conducting these examinations.</p> <p>Traditionally, posturography utilizes a force plate to assess the body's postural sway through the Center of Pressure (CoP) (Chaudhry et al., [<reflink idref="bib6" id="ref7">6</reflink>]; Collings et al., [<reflink idref="bib8" id="ref8">8</reflink>]). While the force plates are considered the "gold standard" for obtaining reliable balance measurements, they are expensive devices and not easily portable, rendering them "impractical" in clinical and sports center settings. In recent years, there has been an increasing interest about the adoption of wearable sensors based on miniaturized Inertial Measurement Units (IMUs) (Grimm & Bolink, [<reflink idref="bib13" id="ref9">13</reflink>]; Neville et al., [<reflink idref="bib28" id="ref10">28</reflink>]). They could represent a valid alternative to the classical force platforms. In fact, they are portable and wireless technological tools, relatively cheap, small and lightweight (Ghislieri et al., [<reflink idref="bib12" id="ref11">12</reflink>]; Marchetti et al., [<reflink idref="bib24" id="ref12">24</reflink>]; Mayagoitia et al., [<reflink idref="bib25" id="ref13">25</reflink>]; Moe-Nilssen & Helbostad, [<reflink idref="bib26" id="ref14">26</reflink>]).</p> <p>Despite this, the integration of wearable sensors into standard posturography practices has not been widely adopted. This hesitation stems from uncertainties regarding the accuracy of IMU-based assessments in balance evaluation compared to the established "gold standard" (i.e. force platforms). Indeed, a review by Ghislieri et al. ([<reflink idref="bib12" id="ref15">12</reflink>]) focused on the wearable inertial sensors to assess standing balance, reported that among 47 studies, ten articles (21%) validated the results against a force plate, and only four articles (8%) also compared the <emph>test-retest reliability</emph>. Of the included articles, 26 articles (55%) used commercial IMUs, and this highlights the importance of validating different tools (Heebner et al., [<reflink idref="bib14" id="ref16">14</reflink>]; Jaworski et al., [<reflink idref="bib15" id="ref17">15</reflink>]; Mancini et al., [<reflink idref="bib22" id="ref18">22</reflink>]; Whitney et al., [<reflink idref="bib38" id="ref19">38</reflink>]).</p> <p>Related to this, Jaworski et al. ([<reflink idref="bib15" id="ref20">15</reflink>]) have investigated the <emph>intra-rater reliability</emph> of the GYKO (wearable 3D inertial sensor) system, located on the upper thoracic back while standing on one foot by showing <emph>moderate</emph> to <emph>good</emph> scores (from 0.62 to 0.70), based on the threshold proposed by Fleiss et al. ([<reflink idref="bib11" id="ref21">11</reflink>]), for all the postural stability measurements. The same authors also tested the reliability in a bipedal standing; the intra-class correlation coefficient (ICC) ranged from <emph>poor</emph> to <emph>good reliability</emph> (from 0.31 to 0.75). However, in their studies, the authors did not compare the results obtained from the GYKO with the "gold standard" to assess its <emph>inter-rater reliability</emph>.</p> <p>Another relevant issue is the choice of methods for measuring static and dynamic balance. In population studies, three groups of tests are most commonly used: standing balance (Jaworski et al., [<reflink idref="bib16" id="ref22">16</reflink>]), walking balance and dynamic balance (Jaworski et al., [<reflink idref="bib17" id="ref23">17</reflink>]). In addition, the maintenance of the upright posture is strongly influenced by the even (stable) or uneven (unstable/perturbed) surface (Davlin, [<reflink idref="bib9" id="ref24">9</reflink>]; Kounalakis et al., [<reflink idref="bib20" id="ref25">20</reflink>]; Promsri et al., [<reflink idref="bib33" id="ref26">33</reflink>]; Rizzato et al., [<reflink idref="bib34" id="ref27">34</reflink>]).</p> <p>Therefore, the main goal of this study was to evaluate the <emph>inter-rater reliability</emph> to assess the absolute agreement between the GYKO inertial sensor system placed in thoracic position and the force plate within different foot positions and various stable/unstable conditions through the time-domain outputs. Moreover, the secondary aim was to assess the <emph>test-retest reliability</emph> to evaluate the consistency between repeated trials.</p> <p>By the end, since there is a lack of information on comparing sensitivity between wearable systems and force plate traditional approaches (Ghislieri et al., [<reflink idref="bib12" id="ref28">12</reflink>]), we want to assess if the Minimal Detectable Change (MDC) is small enough for the specific application under consideration.</p> <hd id="AN0182438457-3">Material and methods</hd> <p></p> <hd id="AN0182438457-4">Participants</hd> <p>Thirty-eight healthy, physically active subjects were recruited for this study (19 males and 19 females; age = 25 ± 3 years; height = 1.71 ± 0.09 m; body mass = 65.7 ± 10.2 kg).</p> <p>The a priori power analysis was conducted using G-Power (3.1.9.2, Heinrich Heine University, Dusseldorf, Germany) to test the difference between two dependent means (matched pairs) with a medium effect size of 0.50 and an alpha of 0.05. Results showed that a total sample of thirty-four participants was required to achieve a power of 0.80.</p> <hd id="AN0182438457-5">Testing protocol</hd> <p>Participants visited the laboratory twice, one week apart at the same time (Jaworski et al., [<reflink idref="bib15" id="ref29">15</reflink>]; Tsigilis et al., [<reflink idref="bib37" id="ref30">37</reflink>]) to examine test i<emph>nter-rater</emph> and <emph>test-retest reliability</emph>. The subjects performed all the tests barefoot, and they were asked to refrain from exercising/sports activities in the 24 hours leading up to the tests.</p> <p>In brief, participants were asked to perform postural stability tests (open eyes) in three foot positions (bipedal standing with feet side-by-side, BS; tandem standing with one foot in front of the other, TS; single standing with the dominant foot on the ground and the contralateral foot raised off the ground, SS) over two different surfaces (stable condition on the floor, F; unstable condition on the BOSU®, BO). All the tests were carried out on a force plate (AMTI, 900 × 900 × 101.6 mm; Watertown, MA; sampling frequency 500 Hz, named device P) while the subjects wore an IMU sensor (GYKO, Microgate, Bolzano, Italy; sampling frequency 500 Hz, named device G) sensor (Jaworski et al., [<reflink idref="bib15" id="ref31">15</reflink>]) positioned at the lumbar level (see Figure 1). The height at which the G system was to be attached was measured trial by trial with a Harpenden stadiometer (Holtain Ltd., Crymych, Pembs, UK). Each trial was replicated three times, lasting 30 s each, interspersed by 30 s of passive resting. All experimental tests were randomized.</p> <p>Graph: Figure 1. Schematic representation of the position of the subjects and the setup used on a force platform or BOSU®.</p> <p>In the static balance test, participants were required to keep their balance on the floor (F that corresponds to the force platform surface), while in the unstable balance test, they were required to stand on a BO (Ø = 65 cm; height = 25.4 cm; flat part facing upwards) positioned above P with extended legs and arms relaxed along the sides of the body. During all trials (three repetitions × position × condition), participants were asked to look at a point on the wall at a distance of 2 m (Jaworski et al., [<reflink idref="bib15" id="ref32">15</reflink>]).</p> <p>Before data collection, the foot position was marked and maintained throughout the entire experiment.</p> <hd id="AN0182438457-6">Variable outcomes</hd> <p>The force plate-based CoP from each trial was filtered (2<sups>nd</sups> order Butterworth filter, cut-off 10 Hz) (Koltermann et al., [<reflink idref="bib18" id="ref33">18</reflink>]). The offline analysis was conducted using custom-developed programs in Matlab (r2022b). The G data has been acquired directly from the company's software (GykoRePower, ver. 11.2.1, Microgate, Bolzano, Italy) without further offline post-processing to maintain the sense of a user-friendly field tool that should not require additional analysis processes from the end user.</p> <p>According to the previous literature (Duarte & Freitas, [<reflink idref="bib10" id="ref34">10</reflink>]; Jaworski et al., [<reflink idref="bib16" id="ref35">16</reflink>]; Prieto et al., [<reflink idref="bib32" id="ref36">32</reflink>]), the following time domain variables have been measured in order to character the postural stability: medio-lateral (ML) length, antero-posterior (AP) length, length, ML mean velocity, AP mean velocity, mean velocity, ML mean distance, AP mean distance, mean distance, ML RMS distance, AP RMS distance, RMS distance, area.</p> <hd id="AN0182438457-7">Statistical analysis</hd> <p>Descriptive statistics were reported as mean ± SD for each index (see Tables 1, 2 and 3).</p> <p>Table 1. Values of mean and standard deviations (SD) of test and retest for P (averaged among three trials in each condition). Results about lower and upper bound for ICC, ICC values, ICC interpretation following the Koo and Li ([<reflink idref="bib19" id="ref37">19</reflink>]) guidelines (cut-off values were: less than 0.50 = <emph>poor reliability</emph>, between 0.50 and 0.75 = <emph>moderate reliability</emph>, between 0.75 and 0.90 = <emph>good reliability</emph> and greater than 0.90 = <emph>excellent reliability</emph>), SEM (used to express absolute measurement reliability (Atkinson & Nevill, [<reflink idref="bib5" id="ref38">5</reflink>]; Jaworski et al., [<reflink idref="bib16" id="ref39">16</reflink>]) according to the following formula:</p> <p>Graph</p> <p> <ephtml> <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="italic">SEM</mi><mo>=</mo><mi mathvariant="italic">SD</mi><mo>×</mo><msqrt><mn>1</mn><mo>−</mo><mi mathvariant="italic">ICC</mi></msqrt></math> </ephtml> ), SEM<subs>%</subs> (calculated as the percentage of the mean value derived from both the test and retest according to the following formula:</p> <p>Graph</p> <p> <ephtml> <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="italic">SE</mi><mrow><msub><mi>M</mi><mi mathvariant="normal">%</mi></msub></mrow><mo>=</mo><mfenced open="(" close=")"><mrow><mrow><mfrac><mrow><mi mathvariant="italic">SEM</mi></mrow><mrow><mi mathvariant="italic">grand</mi><mspace width="thinmathspace" /><mspace width="thinmathspace" /><mi mathvariant="italic">mean</mi></mrow></mfrac></mrow></mrow></mfenced><mo>×</mo><mn>100</mn></math> </ephtml> ), MDC<subs>95</subs> (smallest magnitude of changes required to surpass the measurement error in two consecutive tests within a specific CI. Calculations were conducted for a 95% CI using the formula:</p> <p>Graph</p> <p> <ephtml> <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="italic">MD</mi><mrow><msub><mi>C</mi><mrow><mn>95</mn></mrow></msub></mrow><mo>=</mo><mi mathvariant="italic">SEM</mi><mo>×</mo><mn>1.96</mn><mo>×</mo><mo stretchy="false">√</mo><mn>2</mn></math> </ephtml> ) and MDC<subs>95%</subs> (expressed as the percentage of the mean from the test and retest, according to the formula:</p> <p>Graph</p> <p> <ephtml> <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="italic">MD</mi><mrow><msub><mi>C</mi><mrow><mn>95</mn><mi mathvariant="normal">%</mi></mrow></msub></mrow><mo>=</mo><mfenced open="(" close=")"><mrow><mrow><mfrac><mrow><mi mathvariant="italic">MD</mi><mrow><msub><mi mathvariant="italic">C</mi><mrow><mn>95</mn></mrow></msub></mrow></mrow><mrow><mi mathvariant="italic">grandmean</mi></mrow></mfrac></mrow></mrow></mfenced><mo>×</mo><mn>100</mn><mo stretchy="false">)</mo><mo>.</mo></math> </ephtml> </p> <p> <ephtml> <table><thead><tr><td /><td /><td /><td>Force platform: test vs retest</td></tr><tr><td /><td /><td /><td>Test</td><td>Retest</td><td /><td /><td /><td /><td /><td /><td /><td /></tr><tr><td /><td /><td /><td>Mean</td><td>SD</td><td>Mean</td><td>SD</td><td>Lower bound (95%CI)</td><td>Upper bound (95%CI)</td><td>ICC</td><td>Interpretation ICC</td><td>SEM</td><td>SEM<sub>%</sub></td><td>MDC<sub>95</sub></td><td>MDC<sub>95%</sub></td></tr></thead><tbody><tr><td>Length_ML [mm]</td><td>F</td><td>BS</td><td>140.72</td><td>49.62</td><td>132.36</td><td>49.40</td><td>0.692</td><td>0.908</td><td>0.829</td><td>good</td><td>20.52</td><td>15.03</td><td>56.88</td><td>41.65</td></tr><tr><td>TS</td><td>533.63</td><td>81.79</td><td>543.11</td><td>96.74</td><td>0.487</td><td>0.829</td><td>0.695</td><td>moderate</td><td>45.17</td><td>8.39</td><td>125.21</td><td>23.26</td></tr><tr><td>SS</td><td>711.47</td><td>132.96</td><td>703.15</td><td>138.54</td><td>0.585</td><td>0.868</td><td>0.761</td><td>good</td><td>65.00</td><td>9.19</td><td>180.17</td><td>25.47</td></tr><tr><td>BO</td><td>BS</td><td>556.81</td><td>137.39</td><td>509.88</td><td>110.69</td><td>0.445</td><td>0.855</td><td>0.717</td><td>moderate</td><td>73.09</td><td>13.70</td><td>202.58</td><td>37.98</td></tr><tr><td>TS</td><td>2472.96</td><td>1155.44</td><td>1910.92</td><td>657.92</td><td>0.072</td><td>0.628</td><td>0.386</td><td>poor</td><td>905.38</td><td>41.31</td><td>2509.60</td><td>114.49</td></tr><tr><td>SS</td><td>2156.65</td><td>992.53</td><td>1996.24</td><td>934.81</td><td>0.663</td><td>0.879</td><td>0.810</td><td>good</td><td>432.63</td><td>20.84</td><td>1199.20</td><td>57.75</td></tr><tr><td>Length_AP [mm]</td><td>F</td><td>BS</td><td>200.49</td><td>47.13</td><td>199.40</td><td>45.53</td><td>0.627</td><td>0.884</td><td>0.787</td><td>good</td><td>21.75</td><td>10.88</td><td>60.29</td><td>30.15</td></tr><tr><td>TS</td><td>540.20</td><td>136.54</td><td>544.31</td><td>149.07</td><td>0.661</td><td>0.896</td><td>0.809</td><td>good</td><td>59.67</td><td>11.00</td><td>165.40</td><td>30.50</td></tr><tr><td>SS</td><td>641.98</td><td>131.11</td><td>639.28</td><td>156.40</td><td>0.718</td><td>0.915</td><td>0.843</td><td>good</td><td>51.95</td><td>8.11</td><td>144.00</td><td>22.48</td></tr><tr><td>BO</td><td>BS</td><td>780.65</td><td>189.20</td><td>771.99</td><td>198.26</td><td>0.685</td><td>0.904</td><td>0.823</td><td>good</td><td>79.60</td><td>10.25</td><td>220.64</td><td>28.42</td></tr><tr><td>TS</td><td>842.28</td><td>204.83</td><td>787.06</td><td>264.82</td><td>0.272</td><td>0.727</td><td>0.537</td><td>moderate</td><td>139.38</td><td>17.11</td><td>386.33</td><td>47.42</td></tr><tr><td>SS</td><td>1001.74</td><td>307.19</td><td>896.19</td><td>220.90</td><td>0.333</td><td>0.783</td><td>0.609</td><td>moderate</td><td>192.09</td><td>20.24</td><td>532.44</td><td>56.11</td></tr><tr><td>Length [mm]</td><td>F</td><td>BS</td><td>271.84</td><td>71.90</td><td>265.57</td><td>69.12</td><td>0.686</td><td>0.903</td><td>0.822</td><td>good</td><td>30.33</td><td>11.29</td><td>84.08</td><td>31.29</td></tr><tr><td>TS</td><td>843.18</td><td>154.30</td><td>853.20</td><td>175.65</td><td>0.591</td><td>0.870</td><td>0.765</td><td>good</td><td>74.80</td><td>8.82</td><td>207.34</td><td>24.44</td></tr><tr><td>SS</td><td>1058.25</td><td>178.30</td><td>1050.88</td><td>212.03</td><td>0.653</td><td>0.893</td><td>0.803</td><td>good</td><td>79.14</td><td>7.50</td><td>219.36</td><td>20.80</td></tr><tr><td>BO</td><td>BS</td><td>1064.99</td><td>240.93</td><td>1023.90</td><td>233.70</td><td>0.678</td><td>0.903</td><td>0.820</td><td>good</td><td>102.22</td><td>9.79</td><td>283.34</td><td>27.13</td></tr><tr><td>TS</td><td>2792.28</td><td>1156.98</td><td>2185.80</td><td>693.67</td><td>0.079</td><td>0.657</td><td>0.414</td><td>poor</td><td>885.68</td><td>35.58</td><td>2454.98</td><td>98.63</td></tr><tr><td>SS</td><td>2550.71</td><td>1042.52</td><td>2359.71</td><td>950.19</td><td>0.653</td><td>0.895</td><td>0.806</td><td>good</td><td>459.18</td><td>18.70</td><td>1272.79</td><td>51.84</td></tr><tr><td>Velocity_ML [mm/s]</td><td>F</td><td>BS</td><td>4.69</td><td>1.65</td><td>4.41</td><td>1.65</td><td>0.692</td><td>0.908</td><td>0.829</td><td>good</td><td>0.68</td><td>15.03</td><td>1.90</td><td>41.65</td></tr><tr><td>TS</td><td>17.79</td><td>2.73</td><td>18.10</td><td>3.22</td><td>0.487</td><td>0.829</td><td>0.695</td><td>moderate</td><td>1.51</td><td>8.39</td><td>4.17</td><td>23.26</td></tr><tr><td>SS</td><td>23.72</td><td>4.43</td><td>23.44</td><td>4.62</td><td>0.585</td><td>0.868</td><td>0.761</td><td>good</td><td>2.17</td><td>9.19</td><td>6.01</td><td>25.47</td></tr><tr><td>BO</td><td>BS</td><td>18.56</td><td>4.58</td><td>17.00</td><td>3.69</td><td>0.445</td><td>0.855</td><td>0.717</td><td>moderate</td><td>2.44</td><td>13.70</td><td>6.75</td><td>37.98</td></tr><tr><td>TS</td><td>83.24</td><td>37.99</td><td>63.70</td><td>21.93</td><td>0.061</td><td>0.627</td><td>0.381</td><td>poor</td><td>29.89</td><td>40.68</td><td>82.84</td><td>112.75</td></tr><tr><td>SS</td><td>71.51</td><td>33.28</td><td>66.54</td><td>31.16</td><td>0.668</td><td>0.898</td><td>0.812</td><td>good</td><td>14.43</td><td>20.91</td><td>40.00</td><td>57.95</td></tr><tr><td>Velocity_AP [mm/s]</td><td>F</td><td>BS</td><td>6.68</td><td>1.57</td><td>6.65</td><td>1.52</td><td>0.627</td><td>0.884</td><td>0.787</td><td>good</td><td>0.73</td><td>10.88</td><td>2.01</td><td>30.15</td></tr><tr><td>TS</td><td>18.01</td><td>4.55</td><td>18.14</td><td>4.97</td><td>0.661</td><td>0.896</td><td>0.809</td><td>good</td><td>1.99</td><td>11.00</td><td>5.51</td><td>30.50</td></tr><tr><td>SS</td><td>21.40</td><td>4.37</td><td>21.31</td><td>5.21</td><td>0.718</td><td>0.915</td><td>0.843</td><td>good</td><td>1.73</td><td>8.11</td><td>4.80</td><td>22.48</td></tr><tr><td>BO</td><td>BS</td><td>26.02</td><td>6.31</td><td>25.73</td><td>6.61</td><td>0.685</td><td>0.904</td><td>0.823</td><td>good</td><td>2.65</td><td>10.25</td><td>7.35</td><td>28.42</td></tr><tr><td>TS</td><td>28.08</td><td>6.83</td><td>26.24</td><td>8.83</td><td>0.271</td><td>0.727</td><td>0.536</td><td>moderate</td><td>4.65</td><td>17.13</td><td>12.89</td><td>47.47</td></tr><tr><td>SS</td><td>33.39</td><td>10.24</td><td>29.87</td><td>7.36</td><td>0.333</td><td>0.783</td><td>0.609</td><td>moderate</td><td>6.40</td><td>20.24</td><td>17.75</td><td>56.11</td></tr><tr><td>Velocity [mm/s]</td><td>F</td><td>BS</td><td>9.06</td><td>2.40</td><td>8.81</td><td>2.31</td><td>0.676</td><td>0.900</td><td>0.816</td><td>good</td><td>1.03</td><td>11.50</td><td>2.85</td><td>31.88</td></tr><tr><td>TS</td><td>28.11</td><td>5.14</td><td>28.23</td><td>5.98</td><td>0.535</td><td>0.850</td><td>0.729</td><td>moderate</td><td>2.68</td><td>9.51</td><td>7.42</td><td>26.35</td></tr><tr><td>SS</td><td>35.28</td><td>5.94</td><td>34.61</td><td>7.46</td><td>0.585</td><td>0.867</td><td>0.759</td><td>good</td><td>2.92</td><td>8.35</td><td>8.09</td><td>23.14</td></tr><tr><td>BO</td><td>BS</td><td>35.50</td><td>8.03</td><td>33.96</td><td>7.78</td><td>0.651</td><td>0.895</td><td>0.805</td><td>good</td><td>3.55</td><td>10.21</td><td>9.83</td><td>28.30</td></tr><tr><td>TS</td><td>93.08</td><td>38.57</td><td>73.16</td><td>23.75</td><td>0.078</td><td>0.647</td><td>0.404</td><td>poor</td><td>29.77</td><td>35.82</td><td>82.53</td><td>99.29</td></tr><tr><td>SS</td><td>85.02</td><td>34.75</td><td>77.80</td><td>32.61</td><td>0.620</td><td>0.885</td><td>0.787</td><td>good</td><td>16.04</td><td>19.70</td><td>44.46</td><td>54.61</td></tr><tr><td>Distance_ML [mm]</td><td>F</td><td>BS</td><td>1.56</td><td>0.60</td><td>1.61</td><td>0.77</td><td>0.498</td><td>0.834</td><td>0.703</td><td>moderate</td><td>0.33</td><td>20.61</td><td>0.91</td><td>57.13</td></tr><tr><td>TS</td><td>4.52</td><td>0.75</td><td>4.31</td><td>0.83</td><td>0.583</td><td>0.884</td><td>0.779</td><td>good</td><td>0.35</td><td>7.98</td><td>0.98</td><td>22.11</td></tr><tr><td>SS</td><td>4.46</td><td>0.58</td><td>4.35</td><td>0.72</td><td>0.387</td><td>0.784</td><td>0.624</td><td>moderate</td><td>0.36</td><td>8.09</td><td>0.99</td><td>22.42</td></tr><tr><td>BO</td><td>BS</td><td>6.85</td><td>1.60</td><td>6.73</td><td>1.55</td><td>0.331</td><td>0.762</td><td>0.587</td><td>moderate</td><td>1.03</td><td>15.14</td><td>2.85</td><td>41.96</td></tr><tr><td>TS</td><td>8.37</td><td>2.02</td><td>7.36</td><td>1.55</td><td>0.178</td><td>0.746</td><td>0.531</td><td>moderate</td><td>1.38</td><td>17.59</td><td>3.83</td><td>48.76</td></tr><tr><td>SS</td><td>7.04</td><td>1.59</td><td>6.58</td><td>1.41</td><td>0.506</td><td>0.854</td><td>0.728</td><td>moderate</td><td>0.83</td><td>12.18</td><td>2.30</td><td>33.77</td></tr><tr><td>Distance_AP [mm]</td><td>F</td><td>BS</td><td>3.83</td><td>1.60</td><td>3.77</td><td>1.58</td><td>0.580</td><td>0.866</td><td>0.758</td><td>good</td><td>0.79</td><td>20.70</td><td>2.18</td><td>57.38</td></tr><tr><td>TS</td><td>4.77</td><td>1.68</td><td>4.91</td><td>2.03</td><td>0.207</td><td>0.700</td><td>0.492</td><td>poor</td><td>1.20</td><td>24.69</td><td>3.31</td><td>68.45</td></tr><tr><td>SS</td><td>6.22</td><td>1.32</td><td>6.23</td><td>1.62</td><td>0.362</td><td>0.777</td><td>0.610</td><td>moderate</td><td>0.83</td><td>13.29</td><td>2.29</td><td>36.83</td></tr><tr><td>BO</td><td>BS</td><td>9.45</td><td>2.38</td><td>9.03</td><td>2.16</td><td>0.310</td><td>0.748</td><td>0.567</td><td>moderate</td><td>1.56</td><td>16.93</td><td>4.34</td><td>46.92</td></tr><tr><td>TS</td><td>11.67</td><td>2.64</td><td>11.17</td><td>2.48</td><td>0.438</td><td>0.807</td><td>0.660</td><td>moderate</td><td>1.54</td><td>13.51</td><td>4.27</td><td>37.45</td></tr><tr><td>SS</td><td>10.12</td><td>2.44</td><td>9.25</td><td>1.86</td><td>0.298</td><td>0.761</td><td>0.577</td><td>moderate</td><td>1.59</td><td>16.37</td><td>4.40</td><td>45.39</td></tr><tr><td>Distance [mm]</td><td>F</td><td>BS</td><td>4.44</td><td>1.71</td><td>4.41</td><td>1.70</td><td>0.640</td><td>0.888</td><td>0.796</td><td>good</td><td>0.77</td><td>17.41</td><td>2.14</td><td>48.25</td></tr><tr><td>TS</td><td>7.32</td><td>1.76</td><td>7.31</td><td>2.08</td><td>0.395</td><td>0.792</td><td>0.634</td><td>moderate</td><td>1.07</td><td>14.59</td><td>2.96</td><td>40.43</td></tr><tr><td>SS</td><td>8.45</td><td>1.32</td><td>8.37</td><td>1.70</td><td>0.465</td><td>0.821</td><td>0.682</td><td>moderate</td><td>0.75</td><td>8.88</td><td>2.07</td><td>24.62</td></tr><tr><td>BO</td><td>BS</td><td>12.90</td><td>2.79</td><td>12.45</td><td>2.64</td><td>0.431</td><td>0.804</td><td>0.655</td><td>moderate</td><td>1.64</td><td>12.93</td><td>4.54</td><td>35.84</td></tr><tr><td>TS</td><td>15.89</td><td>3.07</td><td>14.72</td><td>2.73</td><td>0.362</td><td>0.808</td><td>0.643</td><td>moderate</td><td>1.84</td><td>12.00</td><td>5.09</td><td>33.27</td></tr><tr><td>SS</td><td>13.61</td><td>2.79</td><td>12.56</td><td>2.10</td><td>0.333</td><td>0.799</td><td>0.626</td><td>moderate</td><td>1.70</td><td>13.01</td><td>4.72</td><td>36.07</td></tr><tr><td>RMSDistance_ML [mm]</td><td>F</td><td>BS</td><td>2.05</td><td>0.76</td><td>2.04</td><td>0.93</td><td>0.524</td><td>0.845</td><td>0.722</td><td>moderate</td><td>0.40</td><td>19.63</td><td>1.11</td><td>54.41</td></tr><tr><td>TS</td><td>5.69</td><td>0.96</td><td>5.42</td><td>1.07</td><td>0.605</td><td>0.890</td><td>0.790</td><td>good</td><td>0.44</td><td>7.89</td><td>1.22</td><td>21.87</td></tr><tr><td>SS</td><td>5.52</td><td>0.72</td><td>5.44</td><td>0.96</td><td>0.383</td><td>0.785</td><td>0.624</td><td>moderate</td><td>0.44</td><td>8.06</td><td>1.23</td><td>22.35</td></tr><tr><td>BO</td><td>BS</td><td>8.62</td><td>2.02</td><td>8.48</td><td>1.93</td><td>0.356</td><td>0.773</td><td>0.605</td><td>moderate</td><td>1.27</td><td>14.83</td><td>3.52</td><td>41.11</td></tr><tr><td>TS</td><td>10.44</td><td>2.47</td><td>9.19</td><td>1.88</td><td>0.182</td><td>0.763</td><td>0.551</td><td>moderate</td><td>1.65</td><td>16.85</td><td>4.58</td><td>46.70</td></tr><tr><td>SS</td><td>8.79</td><td>1.95</td><td>8.16</td><td>1.70</td><td>0.458</td><td>0.844</td><td>0.705</td><td>moderate</td><td>1.06</td><td>12.49</td><td>2.93</td><td>34.62</td></tr><tr><td>RMSDistance_AP [mm]</td><td>F</td><td>BS</td><td>4.76</td><td>1.86</td><td>4.66</td><td>1.79</td><td>0.591</td><td>0.871</td><td>0.765</td><td>good</td><td>0.90</td><td>19.12</td><td>2.50</td><td>52.99</td></tr><tr><td>TS</td><td>5.97</td><td>2.07</td><td>6.17</td><td>2.41</td><td>0.248</td><td>0.721</td><td>0.524</td><td>moderate</td><td>1.43</td><td>23.52</td><td>3.96</td><td>65.18</td></tr><tr><td>SS</td><td>7.70</td><td>1.58</td><td>7.80</td><td>1.98</td><td>0.406</td><td>0.796</td><td>0.641</td><td>moderate</td><td>0.95</td><td>12.20</td><td>2.62</td><td>33.82</td></tr><tr><td>BO</td><td>BS</td><td>11.76</td><td>2.88</td><td>11.15</td><td>2.48</td><td>0.145</td><td>0.659</td><td>0.435</td><td>poor</td><td>2.16</td><td>18.88</td><td>5.99</td><td>52.32</td></tr><tr><td>TS</td><td>14.62</td><td>3.23</td><td>13.90</td><td>2.83</td><td>0.361</td><td>0.772</td><td>0.604</td><td>moderate</td><td>2.04</td><td>14.27</td><td>5.64</td><td>39.56</td></tr><tr><td>SS</td><td>12.59</td><td>2.93</td><td>11.55</td><td>2.28</td><td>0.312</td><td>0.768</td><td>0.588</td><td>moderate</td><td>1.88</td><td>15.59</td><td>5.22</td><td>43.20</td></tr><tr><td>RMSDistance [mm]</td><td>F</td><td>BS</td><td>5.25</td><td>1.90</td><td>5.17</td><td>1.90</td><td>0.632</td><td>0.885</td><td>0.791</td><td>good</td><td>0.87</td><td>16.64</td><td>2.40</td><td>46.12</td></tr><tr><td>TS</td><td>8.39</td><td>2.02</td><td>8.39</td><td>2.38</td><td>0.433</td><td>0.808</td><td>0.660</td><td>moderate</td><td>1.18</td><td>14.05</td><td>3.27</td><td>38.96</td></tr><tr><td>SS</td><td>9.55</td><td>1.52</td><td>9.57</td><td>2.02</td><td>0.463</td><td>0.821</td><td>0.681</td><td>moderate</td><td>0.86</td><td>8.97</td><td>2.38</td><td>24.86</td></tr><tr><td>BO</td><td>BS</td><td>14.73</td><td>3.23</td><td>14.18</td><td>2.95</td><td>0.421</td><td>0.799</td><td>0.648</td><td>moderate</td><td>1.92</td><td>13.27</td><td>5.32</td><td>36.77</td></tr><tr><td>TS</td><td>18.14</td><td>3.55</td><td>16.88</td><td>3.06</td><td>0.374</td><td>0.805</td><td>0.643</td><td>moderate</td><td>2.12</td><td>12.10</td><td>5.87</td><td>33.54</td></tr><tr><td>SS</td><td>15.51</td><td>3.18</td><td>14.28</td><td>2.40</td><td>0.312</td><td>0.789</td><td>0.612</td><td>moderate</td><td>1.98</td><td>13.31</td><td>5.50</td><td>36.89</td></tr><tr><td>Area [mm<sup>2</sup>]</td><td>F</td><td>BS</td><td>188.94</td><td>162.47</td><td>179.07</td><td>137.91</td><td>0.734</td><td>0.920</td><td>0.852</td><td>good</td><td>62.50</td><td>33.97</td><td>173.25</td><td>94.16</td></tr><tr><td>TS</td><td>643.68</td><td>312.46</td><td>630.31</td><td>333.14</td><td>0.526</td><td>0.846</td><td>0.723</td><td>moderate</td><td>164.45</td><td>25.82</td><td>455.83</td><td>71.56</td></tr><tr><td>SS</td><td>788.30</td><td>214.49</td><td>814.51</td><td>345.79</td><td>0.402</td><td>0.794</td><td>0.637</td><td>moderate</td><td>129.23</td><td>16.12</td><td>358.20</td><td>44.70</td></tr><tr><td>BO</td><td>BS</td><td>1898.78</td><td>773.74</td><td>1771.19</td><td>692.54</td><td>0.429</td><td>0.803</td><td>0.653</td><td>moderate</td><td>455.79</td><td>24.84</td><td>1263.38</td><td>68.85</td></tr><tr><td>TS</td><td>2884.27</td><td>1127.63</td><td>2371.59</td><td>780.22</td><td>0.204</td><td>0.749</td><td>0.541</td><td>moderate</td><td>763.97</td><td>29.07</td><td>2117.61</td><td>80.58</td></tr><tr><td>SS</td><td>2076.44</td><td>835.28</td><td>1787.58</td><td>629.37</td><td>0.404</td><td>0.833</td><td>0.682</td><td>moderate</td><td>471.03</td><td>24.38</td><td>1305.62</td><td>67.58</td></tr></tbody></table> </ephtml> </p> <p>1 Antero-Posterior (AP); Bosu® (BO); Bipedal Standing (BS); Confidence Interval (CI); Intraclass Correlation Coefficient (ICC); Minimal Detectable Change (MDC); Medio-Lateral (ML); Force Platform (P); Root Mean Square (RMS); Standard Error of Measurement (SEM); Single Standing (SS); Tandem Standing (TS).</p> <p>Table 2. Values of mean and standard deviations (SD) of test and retest for G (averaged among three trials in each condition). Results about lower and upper bound for ICC, ICC values, ICC interpretation following the Koo and Li ([<reflink idref="bib19" id="ref40">19</reflink>]) guidelines (cut-off values were: less than 0.50 = <emph>poor reliability</emph>, between 0.50 and 0.75 = <emph>moderate reliability</emph>, between 0.75 and 0.90 = <emph>good reliability</emph> and greater than 0.90 = <emph>excellent reliability</emph>), SEM (used to express absolute measurement reliability (Atkinson & Nevill, [<reflink idref="bib5" id="ref41">5</reflink>]; Jaworski et al., [<reflink idref="bib16" id="ref42">16</reflink>]) according to the following formula:</p> <p>Graph</p> <p> <ephtml> <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="italic">SEM</mi><mo>=</mo><mi mathvariant="italic">SD</mi><mo>×</mo><msqrt><mn>1</mn><mo>−</mo><mi mathvariant="italic">ICC</mi></msqrt></math> </ephtml> ), SEM<subs>%</subs> (calculated as the percentage of the mean value derived from both the test and retest according to the following formula:</p> <p>Graph</p> <p> <ephtml> <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="italic">SE</mi><mrow><msub><mi>M</mi><mi mathvariant="normal">%</mi></msub></mrow><mo>=</mo><mfenced open="(" close=")"><mrow><mrow><mfrac><mrow><mi mathvariant="italic">SEM</mi></mrow><mrow><mi mathvariant="italic">grand</mi><mspace width="thinmathspace" /><mspace width="thinmathspace" /><mi mathvariant="italic">mean</mi></mrow></mfrac></mrow></mrow></mfenced><mo>×</mo><mn>100</mn></math> </ephtml> ), MDC<subs>95</subs> (smallest magnitude of changes required to surpass the measurement error in two consecutive tests within a specific CI. Calculations were conducted for a 95% CI using the formula:</p> <p>Graph</p> <p> <ephtml> <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="italic">MD</mi><mrow><msub><mi>C</mi><mrow><mn>95</mn></mrow></msub></mrow><mo>=</mo><mi mathvariant="italic">SEM</mi><mo>×</mo><mn>1.96</mn><mo>×</mo><mo stretchy="false">√</mo><mn>2</mn></math> </ephtml> ) and MDC<subs>95%</subs> (expressed as the percentage of the mean from the test and retest, according to the formula:</p> <p>Graph</p> <p> <ephtml> <math xmlns="http://www.w3.org/1998/Math/MathML"><mi mathvariant="italic">MD</mi><mrow><msub><mi>C</mi><mrow><mn>95</mn><mi mathvariant="normal">%</mi></mrow></msub></mrow><mo>=</mo><mfenced open="(" close=")"><mrow><mrow><mfrac><mrow><mi mathvariant="italic">MD</mi><mrow><msub><mi mathvariant="italic">C</mi><mrow><mn>95</mn></mrow></msub></mrow></mrow><mrow><mi mathvariant="italic">grand</mi><mspace width="thinmathspace" /><mspace width="thinmathspace" /><mi mathvariant="italic">mean</mi></mrow></mfrac></mrow></mrow></mfenced><mo>×</mo><mn>100</mn><mo stretchy="false">)</mo></math> </ephtml> .</p> <p> <ephtml> <table><thead><tr><td /><td /><td /><td>Gyko: test vs retest</td></tr><tr><td /><td /><td /><td>Test</td><td>Retest</td><td /><td /><td /><td /><td /><td /><td /><td /></tr><tr><td /><td /><td /><td>Mean</td><td>SD</td><td>Mean</td><td>SD</td><td>Lower bound (95%CI)</td><td>Upper bound (95%CI)</td><td>ICC</td><td>Interpretation ICC</td><td>SEM</td><td>SEM<sub>%</sub></td><td>MDC<sub>95</sub></td><td>MDC<sub>95%</sub></td></tr></thead><tbody><tr><td>Length_ML [mm]</td><td>F</td><td>BS</td><td>114.41</td><td>25.85</td><td>114.61</td><td>33.01</td><td>0.607</td><td>0.876</td><td>0.775</td><td>good</td><td>12.26</td><td>10.71</td><td>33.98</td><td>29.68</td></tr><tr><td>TS</td><td>249.68</td><td>76.47</td><td>239.53</td><td>75.79</td><td>0.631</td><td>0.884</td><td>0.778</td><td>good</td><td>36.03</td><td>14.73</td><td>99.87</td><td>40.83</td></tr><tr><td>SS</td><td>434.89</td><td>140.80</td><td>421.52</td><td>154.93</td><td>0.648</td><td>0.890</td><td>0.799</td><td>good</td><td>63.12</td><td>14.74</td><td>174.97</td><td>40.86</td></tr><tr><td>BO</td><td>BS</td><td>790.29</td><td>285.27</td><td>734.58</td><td>239.25</td><td>0.681</td><td>0.910</td><td>0.829</td><td>good</td><td>117.97</td><td>15.47</td><td>326.98</td><td>42.89</td></tr><tr><td>TS</td><td>1464.03</td><td>581.10</td><td>1238.51</td><td>435.52</td><td>0.275</td><td>0.760</td><td>0.570</td><td>moderate</td><td>381.05</td><td>28.20</td><td>1056.22</td><td>78.16</td></tr><tr><td>SS</td><td>934.67</td><td>489.86</td><td>803.94</td><td>424.27</td><td>0.363</td><td>0.776</td><td>0.609</td><td>moderate</td><td>306.31</td><td>35.24</td><td>849.05</td><td>97.67</td></tr><tr><td>Length_AP [mm]</td><td>F</td><td>BS</td><td>253.76</td><td>83.49</td><td>258.73</td><td>82.82</td><td>0.624</td><td>0.882</td><td>0.785</td><td>good</td><td>38.71</td><td>15.11</td><td>107.31</td><td>41.88</td></tr><tr><td>TS</td><td>415.87</td><td>116.27</td><td>420.77</td><td>116.13</td><td>0.602</td><td>0.874</td><td>0.771</td><td>good</td><td>55.64</td><td>13.30</td><td>154.23</td><td>36.87</td></tr><tr><td>SS</td><td>578.93</td><td>154.50</td><td>587.45</td><td>221.33</td><td>0.435</td><td>0.809</td><td>0.661</td><td>moderate</td><td>89.96</td><td>15.42</td><td>249.34</td><td>42.76</td></tr><tr><td>BO</td><td>BS</td><td>639.41</td><td>241.21</td><td>652.74</td><td>231.03</td><td>0.643</td><td>0.889</td><td>0.797</td><td>good</td><td>108.68</td><td>16.82</td><td>301.24</td><td>46.63</td></tr><tr><td>TS</td><td>968.97</td><td>425.69</td><td>877.22</td><td>352.80</td><td>0.435</td><td>0.807</td><td>0.659</td><td>moderate</td><td>248.58</td><td>26.93</td><td>689.03</td><td>74.64</td></tr><tr><td>SS</td><td>849.01</td><td>326.16</td><td>783.30</td><td>299.50</td><td>0.487</td><td>0.829</td><td>0.695</td><td>moderate</td><td>180.13</td><td>22.07</td><td>499.29</td><td>61.18</td></tr><tr><td>Length [mm]</td><td>F</td><td>BS</td><td>300.45</td><td>89.73</td><td>304.65</td><td>94.18</td><td>0.654</td><td>0.893</td><td>0.804</td><td>good</td><td>39.73</td><td>13.13</td><td>110.12</td><td>36.40</td></tr><tr><td>TS</td><td>531.77</td><td>144.39</td><td>529.61</td><td>147.56</td><td>0.705</td><td>0.911</td><td>0.835</td><td>good</td><td>58.65</td><td>11.05</td><td>162.58</td><td>30.63</td></tr><tr><td>SS</td><td>802.55</td><td>213.31</td><td>790.87</td><td>236.35</td><td>0.687</td><td>0.905</td><td>0.824</td><td>good</td><td>89.49</td><td>11.23</td><td>248.05</td><td>31.13</td></tr><tr><td>BO</td><td>BS</td><td>1138.90</td><td>364.70</td><td>1139.68</td><td>384.02</td><td>0.380</td><td>0.785</td><td>0.623</td><td>moderate</td><td>223.93</td><td>19.66</td><td>620.70</td><td>54.48</td></tr><tr><td>TS</td><td>1939.33</td><td>766.56</td><td>1676.21</td><td>588.54</td><td>0.335</td><td>0.781</td><td>0.607</td><td>moderate</td><td>480.55</td><td>26.58</td><td>1332.03</td><td>73.68</td></tr><tr><td>SS</td><td>1369.93</td><td>518.46</td><td>1248.72</td><td>554.90</td><td>0.550</td><td>0.857</td><td>0.740</td><td>moderate</td><td>264.37</td><td>20.19</td><td>732.78</td><td>55.97</td></tr><tr><td>Velocity_ML [mm/s]</td><td>F</td><td>BS</td><td>4.06</td><td>1.10</td><td>3.90</td><td>1.12</td><td>0.190</td><td>0.688</td><td>0.476</td><td>poor</td><td>0.79</td><td>19.94</td><td>2.20</td><td>55.28</td></tr><tr><td>TS</td><td>8.58</td><td>2.69</td><td>8.14</td><td>2.59</td><td>0.540</td><td>0.849</td><td>0.730</td><td>moderate</td><td>1.40</td><td>16.70</td><td>3.87</td><td>46.30</td></tr><tr><td>SS</td><td>14.77</td><td>4.80</td><td>14.53</td><td>5.33</td><td>0.590</td><td>0.870</td><td>0.764</td><td>good</td><td>2.33</td><td>15.91</td><td>6.46</td><td>44.10</td></tr><tr><td>BO</td><td>BS</td><td>26.64</td><td>9.87</td><td>24.95</td><td>8.14</td><td>0.695</td><td>0.911</td><td>0.833</td><td>good</td><td>4.04</td><td>15.64</td><td>11.19</td><td>43.36</td></tr><tr><td>TS</td><td>49.28</td><td>20.02</td><td>42.09</td><td>14.81</td><td>0.285</td><td>0.754</td><td>0.567</td><td>moderate</td><td>13.17</td><td>28.83</td><td>36.51</td><td>79.92</td></tr><tr><td>SS</td><td>29.77</td><td>12.94</td><td>27.14</td><td>14.51</td><td>0.581</td><td>0.866</td><td>0.758</td><td>good</td><td>6.36</td><td>22.37</td><td>17.64</td><td>62.00</td></tr><tr><td>Velocity_AP [mm/s]</td><td>F</td><td>BS</td><td>8.53</td><td>2.92</td><td>8.79</td><td>2.82</td><td>0.607</td><td>0.875</td><td>0.774</td><td>good</td><td>1.39</td><td>16.02</td><td>3.85</td><td>44.42</td></tr><tr><td>TS</td><td>14.02</td><td>4.05</td><td>14.30</td><td>3.96</td><td>0.618</td><td>0.880</td><td>0.781</td><td>good</td><td>1.90</td><td>13.40</td><td>5.26</td><td>37.13</td></tr><tr><td>SS</td><td>19.62</td><td>5.29</td><td>19.59</td><td>5.66</td><td>0.688</td><td>0.905</td><td>0.825</td><td>good</td><td>2.21</td><td>11.28</td><td>6.13</td><td>31.27</td></tr><tr><td>BO</td><td>BS</td><td>22.36</td><td>7.42</td><td>22.05</td><td>7.75</td><td>0.700</td><td>0.909</td><td>0.832</td><td>good</td><td>3.04</td><td>13.70</td><td>8.43</td><td>37.98</td></tr><tr><td>TS</td><td>33.32</td><td>14.61</td><td>29.81</td><td>11.98</td><td>0.412</td><td>0.798</td><td>0.644</td><td>moderate</td><td>8.72</td><td>27.61</td><td>24.16</td><td>76.53</td></tr><tr><td>SS</td><td>29.17</td><td>11.32</td><td>26.62</td><td>10.19</td><td>0.451</td><td>0.814</td><td>0.671</td><td>moderate</td><td>6.49</td><td>23.28</td><td>18.00</td><td>64.52</td></tr><tr><td>Velocity [mm/s]</td><td>F</td><td>BS</td><td>10.06</td><td>3.17</td><td>10.36</td><td>3.21</td><td>0.653</td><td>0.892</td><td>0.802</td><td>good</td><td>1.41</td><td>13.83</td><td>3.91</td><td>38.33</td></tr><tr><td>TS</td><td>17.76</td><td>5.26</td><td>17.98</td><td>5.03</td><td>0.605</td><td>0.876</td><td>0.774</td><td>good</td><td>2.50</td><td>14.00</td><td>6.93</td><td>38.81</td></tr><tr><td>SS</td><td>26.81</td><td>7.95</td><td>26.87</td><td>8.04</td><td>0.609</td><td>0.877</td><td>0.776</td><td>good</td><td>3.76</td><td>14.02</td><td>10.43</td><td>38.86</td></tr><tr><td>BO</td><td>BS</td><td>38.12</td><td>13.22</td><td>36.96</td><td>11.28</td><td>0.692</td><td>0.905</td><td>0.826</td><td>good</td><td>5.51</td><td>14.69</td><td>15.28</td><td>40.71</td></tr><tr><td>TS</td><td>64.27</td><td>27.51</td><td>55.74</td><td>21.50</td><td>0.286</td><td>0.740</td><td>0.554</td><td>moderate</td><td>18.37</td><td>30.62</td><td>50.92</td><td>84.86</td></tr><tr><td>SS</td><td>45.99</td><td>18.42</td><td>42.42</td><td>18.87</td><td>0.548</td><td>0.853</td><td>0.736</td><td>moderate</td><td>9.46</td><td>21.41</td><td>26.23</td><td>59.34</td></tr><tr><td>Distance_ML [mm]</td><td>F</td><td>BS</td><td>2.14</td><td>0.95</td><td>2.15</td><td>1.43</td><td>0.199</td><td>0.698</td><td>0.488</td><td>poor</td><td>0.68</td><td>31.67</td><td>1.88</td><td>87.79</td></tr><tr><td>TS</td><td>5.57</td><td>2.71</td><td>5.25</td><td>2.71</td><td>0.613</td><td>0.877</td><td>0.777</td><td>good</td><td>1.28</td><td>23.61</td><td>3.54</td><td>65.44</td></tr><tr><td>SS</td><td>8.48</td><td>3.36</td><td>8.26</td><td>3.58</td><td>0.488</td><td>0.830</td><td>0.697</td><td>moderate</td><td>1.85</td><td>22.11</td><td>5.13</td><td>61.27</td></tr><tr><td>BO</td><td>BS</td><td>12.02</td><td>4.70</td><td>11.36</td><td>3.43</td><td>0.514</td><td>0.838</td><td>0.712</td><td>moderate</td><td>2.52</td><td>21.58</td><td>6.99</td><td>59.81</td></tr><tr><td>TS</td><td>15.41</td><td>5.82</td><td>13.92</td><td>4.60</td><td>0.384</td><td>0.786</td><td>0.625</td><td>moderate</td><td>3.56</td><td>24.31</td><td>9.88</td><td>67.37</td></tr><tr><td>SS</td><td>12.11</td><td>4.87</td><td>11.00</td><td>5.14</td><td>0.372</td><td>0.777</td><td>0.612</td><td>moderate</td><td>3.04</td><td>26.26</td><td>8.41</td><td>72.79</td></tr><tr><td>Distance_AP [mm]</td><td>F</td><td>BS</td><td>6.83</td><td>3.44</td><td>6.62</td><td>3.97</td><td>0.507</td><td>0.838</td><td>0.710</td><td>moderate</td><td>1.85</td><td>27.50</td><td>5.13</td><td>76.24</td></tr><tr><td>TS</td><td>9.27</td><td>3.50</td><td>8.87</td><td>3.78</td><td>0.524</td><td>0.843</td><td>0.719</td><td>moderate</td><td>1.86</td><td>20.46</td><td>5.14</td><td>56.71</td></tr><tr><td>SS</td><td>11.17</td><td>3.75</td><td>11.18</td><td>4.89</td><td>0.304</td><td>0.750</td><td>0.568</td><td>moderate</td><td>2.46</td><td>22.03</td><td>6.82</td><td>61.07</td></tr><tr><td>BO</td><td>BS</td><td>12.65</td><td>5.08</td><td>12.39</td><td>5.15</td><td>0.434</td><td>0.808</td><td>0.661</td><td>moderate</td><td>2.96</td><td>23.60</td><td>8.19</td><td>65.42</td></tr><tr><td>TS</td><td>15.02</td><td>6.20</td><td>14.32</td><td>5.82</td><td>0.368</td><td>0.778</td><td>0.612</td><td>moderate</td><td>3.86</td><td>26.33</td><td>10.70</td><td>72.98</td></tr><tr><td>SS</td><td>14.57</td><td>4.52</td><td>14.24</td><td>6.11</td><td>0.471</td><td>0.824</td><td>0.686</td><td>moderate</td><td>2.53</td><td>17.57</td><td>7.02</td><td>48.70</td></tr><tr><td>Distance [mm]</td><td>F</td><td>BS</td><td>3.81</td><td>1.79</td><td>3.90</td><td>2.28</td><td>0.460</td><td>0.819</td><td>0.678</td><td>moderate</td><td>1.01</td><td>26.30</td><td>2.81</td><td>72.90</td></tr><tr><td>TS</td><td>5.45</td><td>2.18</td><td>5.50</td><td>2.78</td><td>0.494</td><td>0.833</td><td>0.701</td><td>moderate</td><td>1.19</td><td>21.76</td><td>3.30</td><td>60.33</td></tr><tr><td>SS</td><td>7.06</td><td>2.41</td><td>7.28</td><td>3.25</td><td>0.519</td><td>0.842</td><td>0.717</td><td>moderate</td><td>1.28</td><td>17.89</td><td>3.56</td><td>49.60</td></tr><tr><td>BO</td><td>BS</td><td>8.84</td><td>3.16</td><td>8.37</td><td>3.02</td><td>0.527</td><td>0.844</td><td>0.721</td><td>moderate</td><td>1.67</td><td>19.42</td><td>4.63</td><td>53.83</td></tr><tr><td>TS</td><td>11.28</td><td>4.29</td><td>10.32</td><td>3.17</td><td>0.416</td><td>0.799</td><td>0.646</td><td>moderate</td><td>2.55</td><td>23.61</td><td>7.07</td><td>65.43</td></tr><tr><td>SS</td><td>9.99</td><td>5.70</td><td>9.32</td><td>4.12</td><td>0.040</td><td>0.602</td><td>0.353</td><td>poor</td><td>4.58</td><td>47.46</td><td>12.71</td><td>131.55</td></tr><tr><td>RMSDistance_ML [mm]</td><td>F</td><td>BS</td><td>2.78</td><td>1.28</td><td>2.77</td><td>2.06</td><td>0.176</td><td>0.686</td><td>0.470</td><td>poor</td><td>0.93</td><td>33.72</td><td>2.59</td><td>93.46</td></tr><tr><td>TS</td><td>7.04</td><td>3.36</td><td>6.78</td><td>3.80</td><td>0.554</td><td>0.856</td><td>0.740</td><td>moderate</td><td>1.71</td><td>24.77</td><td>4.74</td><td>68.66</td></tr><tr><td>SS</td><td>10.91</td><td>4.51</td><td>10.80</td><td>5.09</td><td>0.470</td><td>0.824</td><td>0.686</td><td>moderate</td><td>2.53</td><td>23.30</td><td>7.01</td><td>64.59</td></tr><tr><td>BO</td><td>BS</td><td>15.35</td><td>6.32</td><td>16.67</td><td>14.59</td><td>0.056</td><td>0.613</td><td>0.368</td><td>poor</td><td>5.02</td><td>31.37</td><td>13.92</td><td>86.96</td></tr><tr><td>TS</td><td>19.85</td><td>7.84</td><td>18.06</td><td>6.12</td><td>0.386</td><td>0.785</td><td>0.624</td><td>moderate</td><td>4.81</td><td>25.36</td><td>13.33</td><td>70.29</td></tr><tr><td>SS</td><td>15.59</td><td>6.83</td><td>13.98</td><td>6.79</td><td>0.371</td><td>0.776</td><td>0.612</td><td>moderate</td><td>4.25</td><td>28.77</td><td>11.79</td><td>79.75</td></tr><tr><td>RMSDistance_AP [mm]</td><td>F</td><td>BS</td><td>8.69</td><td>4.31</td><td>8.45</td><td>5.11</td><td>0.429</td><td>0.806</td><td>0.657</td><td>moderate</td><td>2.53</td><td>29.47</td><td>7.00</td><td>81.69</td></tr><tr><td>TS</td><td>11.44</td><td>4.24</td><td>11.29</td><td>5.16</td><td>0.535</td><td>0.849</td><td>0.729</td><td>moderate</td><td>2.21</td><td>19.44</td><td>6.12</td><td>53.88</td></tr><tr><td>SS</td><td>14.04</td><td>4.47</td><td>14.11</td><td>6.07</td><td>0.352</td><td>0.773</td><td>0.603</td><td>moderate</td><td>2.81</td><td>20.00</td><td>7.80</td><td>55.44</td></tr><tr><td>BO</td><td>BS</td><td>15.87</td><td>6.23</td><td>15.63</td><td>6.35</td><td>0.422</td><td>0.803</td><td>0.652</td><td>moderate</td><td>3.68</td><td>23.34</td><td>10.19</td><td>64.68</td></tr><tr><td>TS</td><td>19.40</td><td>7.87</td><td>18.25</td><td>7.09</td><td>0.410</td><td>0.795</td><td>0.640</td><td>moderate</td><td>4.72</td><td>25.08</td><td>13.09</td><td>69.52</td></tr><tr><td>SS</td><td>18.35</td><td>5.58</td><td>17.91</td><td>7.66</td><td>0.415</td><td>0.800</td><td>0.647</td><td>moderate</td><td>3.31</td><td>18.28</td><td>9.18</td><td>50.66</td></tr><tr><td>RMSDistance [mm]</td><td>F</td><td>BS</td><td>5.05</td><td>2.37</td><td>5.14</td><td>3.09</td><td>0.396</td><td>0.792</td><td>0.635</td><td>moderate</td><td>1.43</td><td>28.13</td><td>3.97</td><td>77.97</td></tr><tr><td>TS</td><td>7.09</td><td>2.74</td><td>7.19</td><td>3.93</td><td>0.423</td><td>0.804</td><td>0.653</td><td>moderate</td><td>1.61</td><td>22.57</td><td>4.47</td><td>62.57</td></tr><tr><td>SS</td><td>9.16</td><td>3.24</td><td>9.62</td><td>4.88</td><td>0.426</td><td>0.803</td><td>0.653</td><td>moderate</td><td>1.91</td><td>20.35</td><td>5.30</td><td>56.41</td></tr><tr><td>BO</td><td>BS</td><td>11.57</td><td>4.27</td><td>11.06</td><td>3.79</td><td>0.516</td><td>0.840</td><td>0.714</td><td>moderate</td><td>2.29</td><td>20.20</td><td>6.34</td><td>55.99</td></tr><tr><td>TS</td><td>15.08</td><td>5.71</td><td>13.86</td><td>4.62</td><td>0.406</td><td>0.793</td><td>0.637</td><td>moderate</td><td>3.44</td><td>23.77</td><td>9.54</td><td>65.90</td></tr><tr><td>SS</td><td>12.63</td><td>4.78</td><td>12.11</td><td>5.39</td><td>0.392</td><td>0.789</td><td>0.630</td><td>moderate</td><td>2.91</td><td>23.52</td><td>8.06</td><td>65.19</td></tr><tr><td>Area [mm<sup>2</sup>]</td><td>F</td><td>BS</td><td>423.16</td><td>421.02</td><td>434.92</td><td>506.78</td><td>0.737</td><td>0.921</td><td>0.854</td><td>good</td><td>160.87</td><td>37.50</td><td>445.91</td><td>103.93</td></tr><tr><td>TS</td><td>1402.99</td><td>1201.92</td><td>1551.13</td><td>2366.80</td><td>0.450</td><td>0.814</td><td>0.671</td><td>moderate</td><td>689.40</td><td>46.67</td><td>1910.92</td><td>129.37</td></tr><tr><td>SS</td><td>2770.26</td><td>1805.88</td><td>2981.80</td><td>2619.05</td><td>0.628</td><td>0.883</td><td>0.787</td><td>good</td><td>833.45</td><td>28.98</td><td>2310.20</td><td>80.33</td></tr><tr><td>BO</td><td>BS</td><td>4660.36</td><td>3450.36</td><td>4353.84</td><td>2858.59</td><td>0.471</td><td>0.822</td><td>0.684</td><td>moderate</td><td>1939.58</td><td>43.03</td><td>5376.24</td><td>119.28</td></tr><tr><td>TS</td><td>6986.40</td><td>5195.20</td><td>6279.64</td><td>4468.48</td><td>0.462</td><td>0.818</td><td>0.677</td><td>moderate</td><td>2952.59</td><td>44.51</td><td>8184.17</td><td>123.39</td></tr><tr><td>SS</td><td>5192.27</td><td>3636.49</td><td>4730.66</td><td>4556.77</td><td>0.354</td><td>0.771</td><td>0.602</td><td>moderate</td><td>2294.16</td><td>46.24</td><td>6359.09</td><td>128.17</td></tr></tbody></table> </ephtml> </p> <p>2 Antero-Posterior (AP); Bosu® (BO); Bipedal Standing (BS); Confidence Interval (CI); GYKO (G); Intraclass Correlation Coefficient (ICC); Minimal Detectable Change (MDC); Medio-Lateral (ML); Root Mean Square (RMS); Standard Error of Measurement (SEM); Single Standing (SS); Tandem Standing (TS).</p> <p>Table 3. ICC results from G vs P (test and retest are averaged among them to obtain a single value for ICC analysis) and resulting interpretation following the Koo and Li ([<reflink idref="bib19" id="ref43">19</reflink>]) guidelines (cut-off values were: less than 0.50 = <emph>poor reliability</emph>, between 0.50 and 0.75 = <emph>moderate reliability</emph>, between 0.75 and 0.90 = <emph>good reliability</emph> and greater than 0.90 = <emph>excellent reliability</emph>), RMSE and Mean Diff. between two devices.</p> <p> <ephtml> <table><thead><tr><td>Mean Test & Retest: Platform vs. Gyko</td></tr><tr><td /><td /><td /><td>Lower bound (95%CI)</td><td>Upper bound (95%CI)</td><td>ICC</td><td>Interpretation ICC</td><td>RMSE</td><td>Mean Diff.</td></tr></thead><tbody><tr><td>Length_ML [mm]</td><td>F</td><td>BS</td><td>0.189</td><td>0.773</td><td>0.564</td><td>moderate</td><td>38.99</td><td>22.03</td></tr><tr><td>TS</td><td>−0.026</td><td>0.276</td><td>0.069</td><td>poor</td><td>302.25</td><td>293.77</td></tr><tr><td>SS</td><td>−0.076</td><td>0.442</td><td>0.149</td><td>poor</td><td>310.49</td><td>279.11</td></tr><tr><td>BO</td><td>BS</td><td>−0.092</td><td>0.637</td><td>0.323</td><td>poor</td><td>295.63</td><td>−229.09</td></tr><tr><td>TS</td><td>−0.096</td><td>0.752</td><td>0.410</td><td>poor</td><td>957.65</td><td>840.67</td></tr><tr><td>SS</td><td>−0.093</td><td>0.529</td><td>0.208</td><td>poor</td><td>1395.56</td><td>1207.14</td></tr><tr><td>Length_AP [mm]</td><td>F</td><td>BS</td><td>−0.030</td><td>0.689</td><td>0.408</td><td>poor</td><td>81.24</td><td>−56.30</td></tr><tr><td>TS</td><td>−0.096</td><td>0.805</td><td>0.509</td><td>moderate</td><td>149.60</td><td>123.93</td></tr><tr><td>SS</td><td>0.459</td><td>0.858</td><td>0.723</td><td>moderate</td><td>120.30</td><td>57.44</td></tr><tr><td>BO</td><td>BS</td><td>0.122</td><td>0.814</td><td>0.599</td><td>moderate</td><td>200.72</td><td>130.25</td></tr><tr><td>TS</td><td>0.465</td><td>0.868</td><td>0.737</td><td>moderate</td><td>218.67</td><td>−108.42</td></tr><tr><td>SS</td><td>0.238</td><td>0.909</td><td>0.764</td><td>good</td><td>194.13</td><td>132.81</td></tr><tr><td>Length [mm]</td><td>F</td><td>BS</td><td>0.352</td><td>0.826</td><td>0.662</td><td>moderate</td><td>66.82</td><td>−33.85</td></tr><tr><td>TS</td><td>−0.051</td><td>0.579</td><td>0.218</td><td>poor</td><td>335.57</td><td>317.50</td></tr><tr><td>SS</td><td>−0.093</td><td>0.761</td><td>0.420</td><td>poor</td><td>291.79</td><td>257.85</td></tr><tr><td>BO</td><td>BS</td><td>0.350</td><td>0.775</td><td>0.605</td><td>moderate</td><td>260.94</td><td>−94.85</td></tr><tr><td>TS</td><td>−0.091</td><td>0.857</td><td>0.586</td><td>moderate</td><td>793.59</td><td>681.27</td></tr><tr><td>SS</td><td>−0.097</td><td>0.647</td><td>0.298</td><td>poor</td><td>1313.50</td><td>1145.89</td></tr><tr><td>Velocity_ML [mm/s]</td><td>F</td><td>BS</td><td>0.230</td><td>0.723</td><td>0.521</td><td>moderate</td><td>1.33</td><td>0.57</td></tr><tr><td>TS</td><td>−0.027</td><td>0.287</td><td>0.073</td><td>poor</td><td>9.88</td><td>9.59</td></tr><tr><td>SS</td><td>−0.080</td><td>0.462</td><td>0.161</td><td>poor</td><td>10.02</td><td>8.93</td></tr><tr><td>BO</td><td>BS</td><td>−0.093</td><td>0.619</td><td>0.306</td><td>poor</td><td>10.33</td><td>−8.02</td></tr><tr><td>TS</td><td>−0.094</td><td>0.761</td><td>0.420</td><td>poor</td><td>31.52</td><td>27.78</td></tr><tr><td>SS</td><td>−0.092</td><td>0.526</td><td>0.205</td><td>poor</td><td>46.70</td><td>40.57</td></tr><tr><td>Velocity_AP [mm/s]</td><td>F</td><td>BS</td><td>−0.042</td><td>0.685</td><td>0.399</td><td>poor</td><td>2.83</td><td>−2.00</td></tr><tr><td>TS</td><td>−0.088</td><td>0.819</td><td>0.538</td><td>moderate</td><td>4.80</td><td>3.91</td></tr><tr><td>SS</td><td>0.495</td><td>0.878</td><td>0.755</td><td>good</td><td>3.55</td><td>1.75</td></tr><tr><td>BO</td><td>BS</td><td>0.223</td><td>0.814</td><td>0.620</td><td>moderate</td><td>6.27</td><td>3.67</td></tr><tr><td>TS</td><td>0.359</td><td>0.852</td><td>0.696</td><td>moderate</td><td>8.07</td><td>−4.41</td></tr><tr><td>SS</td><td>0.409</td><td>0.911</td><td>0.790</td><td>good</td><td>6.09</td><td>3.74</td></tr><tr><td>Velocity [mm/s]</td><td>F</td><td>BS</td><td>0.299</td><td>0.812</td><td>0.635</td><td>moderate</td><td>2.39</td><td>−1.27</td></tr><tr><td>TS</td><td>−0.057</td><td>0.588</td><td>0.227</td><td>poor</td><td>10.98</td><td>10.30</td></tr><tr><td>SS</td><td>−0.101</td><td>0.770</td><td>0.444</td><td>poor</td><td>9.48</td><td>8.10</td></tr><tr><td>BO</td><td>BS</td><td>0.417</td><td>0.803</td><td>0.651</td><td>moderate</td><td>8.37</td><td>−2.81</td></tr><tr><td>TS</td><td>−0.091</td><td>0.841</td><td>0.567</td><td>moderate</td><td>27.64</td><td>23.11</td></tr><tr><td>SS</td><td>−0.099</td><td>0.662</td><td>0.315</td><td>poor</td><td>42.99</td><td>37.20</td></tr><tr><td>Distance_ML [mm]</td><td>F</td><td>BS</td><td>0.024</td><td>0.582</td><td>0.329</td><td>poor</td><td>1.10</td><td>−0.56</td></tr><tr><td>TS</td><td>0.018</td><td>0.563</td><td>0.312</td><td>poor</td><td>2.34</td><td>−1.00</td></tr><tr><td>SS</td><td>−0.080</td><td>0.322</td><td>0.098</td><td>poor</td><td>4.85</td><td>−3.97</td></tr><tr><td>BO</td><td>BS</td><td>−0.091</td><td>0.468</td><td>0.173</td><td>poor</td><td>5.77</td><td>−4.90</td></tr><tr><td>TS</td><td>−0.083</td><td>0.444</td><td>0.154</td><td>poor</td><td>7.76</td><td>−6.80</td></tr><tr><td>SS</td><td>−0.090</td><td>0.315</td><td>0.093</td><td>poor</td><td>6.35</td><td>−4.75</td></tr><tr><td>Distance_AP [mm]</td><td>F</td><td>BS</td><td>−0.079</td><td>0.595</td><td>0.296</td><td>poor</td><td>3.97</td><td>−2.93</td></tr><tr><td>TS</td><td>−0.097</td><td>0.545</td><td>0.223</td><td>poor</td><td>4.96</td><td>−4.22</td></tr><tr><td>SS</td><td>−0.088</td><td>0.426</td><td>0.151</td><td>poor</td><td>5.89</td><td>−4.95</td></tr><tr><td>BO</td><td>BS</td><td>−0.054</td><td>0.512</td><td>0.243</td><td>poor</td><td>5.22</td><td>−3.28</td></tr><tr><td>TS</td><td>−0.104</td><td>0.410</td><td>0.149</td><td>poor</td><td>6.15</td><td>−3.25</td></tr><tr><td>SS</td><td>−0.162</td><td>0.203</td><td>−0.005</td><td>poor</td><td>7.06</td><td>−4.72</td></tr><tr><td>Distance [mm]</td><td>F</td><td>BS</td><td>0.344</td><td>0.771</td><td>0.599</td><td>moderate</td><td>1.60</td><td>0.57</td></tr><tr><td>TS</td><td>−0.054</td><td>0.759</td><td>0.477</td><td>poor</td><td>2.47</td><td>1.84</td></tr><tr><td>SS</td><td>0.131</td><td>0.698</td><td>0.469</td><td>poor</td><td>2.35</td><td>1.24</td></tr><tr><td>BO</td><td>BS</td><td>−0.100</td><td>0.590</td><td>0.257</td><td>poor</td><td>4.78</td><td>4.07</td></tr><tr><td>TS</td><td>−0.099</td><td>0.555</td><td>0.237</td><td>poor</td><td>5.45</td><td>4.50</td></tr><tr><td>SS</td><td>−0.105</td><td>0.357</td><td>0.113</td><td>poor</td><td>5.42</td><td>3.43</td></tr><tr><td>RMSDistance_ML [mm]</td><td>F</td><td>BS</td><td>0.003</td><td>0.552</td><td>0.298</td><td>poor</td><td>1.51</td><td>−0.72</td></tr><tr><td>TS</td><td>0.006</td><td>0.552</td><td>0.299</td><td>poor</td><td>3.10</td><td>−1.35</td></tr><tr><td>SS</td><td>−0.081</td><td>0.322</td><td>0.098</td><td>poor</td><td>6.62</td><td>−5.37</td></tr><tr><td>BO</td><td>BS</td><td>−0.098</td><td>0.360</td><td>0.118</td><td>poor</td><td>11.23</td><td>−7.46</td></tr><tr><td>TS</td><td>−0.082</td><td>0.424</td><td>0.144</td><td>poor</td><td>10.44</td><td>−9.14</td></tr><tr><td>SS</td><td>−0.090</td><td>0.321</td><td>0.096</td><td>poor</td><td>8.48</td><td>−6.31</td></tr><tr><td>RMSDistance_AP [mm]</td><td>F</td><td>BS</td><td>−0.086</td><td>0.558</td><td>0.261</td><td>poor</td><td>5.16</td><td>−3.86</td></tr><tr><td>TS</td><td>−0.097</td><td>0.532</td><td>0.217</td><td>poor</td><td>6.30</td><td>−5.29</td></tr><tr><td>SS</td><td>−0.087</td><td>0.423</td><td>0.148</td><td>poor</td><td>7.43</td><td>−6.32</td></tr><tr><td>BO</td><td>BS</td><td>−0.070</td><td>0.475</td><td>0.208</td><td>poor</td><td>6.63</td><td>−4.30</td></tr><tr><td>TS</td><td>−0.125</td><td>0.359</td><td>0.106</td><td>poor</td><td>8.08</td><td>−4.56</td></tr><tr><td>SS</td><td>−0.156</td><td>0.195</td><td>−0.006</td><td>poor</td><td>8.86</td><td>−6.06</td></tr><tr><td>RMSDistance [mm]</td><td>F</td><td>BS</td><td>0.382</td><td>0.786</td><td>0.624</td><td>moderate</td><td>1.87</td><td>0.12</td></tr><tr><td>TS</td><td>0.249</td><td>0.762</td><td>0.566</td><td>moderate</td><td>2.54</td><td>1.25</td></tr><tr><td>SS</td><td>0.211</td><td>0.703</td><td>0.497</td><td>poor</td><td>2.90</td><td>0.17</td></tr><tr><td>BO</td><td>BS</td><td>−0.048</td><td>0.650</td><td>0.362</td><td>poor</td><td>4.48</td><td>3.14</td></tr><tr><td>TS</td><td>0.005</td><td>0.602</td><td>0.340</td><td>poor</td><td>5.15</td><td>3.04</td></tr><tr><td>SS</td><td>−0.117</td><td>0.413</td><td>0.146</td><td>poor</td><td>5.35</td><td>2.53</td></tr><tr><td>Area [mm<sup>2</sup>]</td><td>F</td><td>BS</td><td>−0.035</td><td>0.513</td><td>0.252</td><td>poor</td><td>455.92</td><td>−245.04</td></tr><tr><td>TS</td><td>−0.071</td><td>0.465</td><td>0.202</td><td>poor</td><td>1711.61</td><td>−840.07</td></tr><tr><td>SS</td><td>−0.090</td><td>0.330</td><td>0.101</td><td>poor</td><td>2810.93</td><td>−2074.63</td></tr><tr><td>BO</td><td>BS</td><td>−0.087</td><td>0.422</td><td>0.161</td><td>poor</td><td>3648.88</td><td>−2672.12</td></tr><tr><td>TS</td><td>−0.094</td><td>0.346</td><td>0.110</td><td>poor</td><td>5665.33</td><td>−4005.09</td></tr><tr><td>SS</td><td>−0.130</td><td>0.277</td><td>0.052</td><td>poor</td><td>4658.55</td><td>−3029.46</td></tr></tbody></table> </ephtml> </p> <p>3 Antero-Posterior (AP); Bosu® (BO); Bipedal Standing (BS); Confidence Interval (CI); GYKO (G); Intraclass Correlation Coefficient (ICC); Medio-Lateral (ML); Mean Difference (Mean Diff.); Force Platform (P); Root Mean Square (RMS); Root Mean Square Error (RMSE); Single Standing (SS); Tandem Standing (TS).</p> <p>The reliability of the repeated test was assessed through the intraclass correlation coefficient (ICC) along with a 95% confidence interval (95% CI). Specifically, the means and SD were calculated by averaging the three trials. The ICC was used: i) to evaluate the consistency of the same device between sessions (<emph>test-retest reliability</emph>, 2-way mixed-effects model, absolute agreement, multiple measurements); ii) to evaluate the absolute agreement among devices within the same trials (<emph>inter-rater reliability</emph>, 2-way mixed-effects model, absolute agreement, multiple measurements) (Koo & Li, [<reflink idref="bib19" id="ref44">19</reflink>]). The outputs of each of the three trials were averaged to obtain one single value.</p> <p>Moreover, to assess the agreement between measurement devices, we employed the Bland-Altman plots. For position × condition, we computed the differences between devices. Concordance intervals were defined as the mean differences ±1.96 times the SD of the differences.</p> <p>We also computed standard error of measurement (SEM), which is used to express absolute measurement reliability (Atkinson & Nevill, [<reflink idref="bib5" id="ref45">5</reflink>]). Then, the SEM was calculated as the percentage of the mean value derived from both the test and retest. This was done to facilitate the comparison of absolute reliability across measurements obtained in different units. SEM was utilized to assess the minimal detectable change (MDC<subs>95</subs>), which is understood as the smallest magnitude of changes required to surpass the measurement error in two consecutive tests within a specific confidence interval (CI). Then, MDC<subs>95</subs> was expressed as the percentage of the mean from the test and retest (Atkinson & Nevill, [<reflink idref="bib5" id="ref46">5</reflink>]; Jaworski et al., [<reflink idref="bib16" id="ref47">16</reflink>]). Then, we also calculated the Root Mean Square Error (RMSE; G = "observed" values; P = "predicted" values) and the Mean Difference between the two devices.</p> <p>The statistical analyses for ICC were performed with SPSS 22 (IBM Corp., Armonk, NY, USA). The violin-plots (Figure 2) were performed with GraphPad Prism (ver. 9.0.0), while the Bland-Altman Plot (Figure 3) were performed with JASP (ver. 0.18.3).</p> <p>Graph: Figure 2. The violin plot shows the distribution for all the parameters assessed in the test vs. retest on both F and BO. Violet and gray colors represent test vs. retest, respectively, for P, while red and blue ones represent test vs. retest for G. Each plot was created averaging all the foot positions. This visualization provides insights into the shape, spread, and central tendency of the data, offering a comprehensive view of its distribution. Dashed lines show the median value, while the dotted line shows the quartiles. Antero-Posterior (AP); Bosu® (BO); GYKO (G); Medio-Lateral (ML); Root Mean Square (RMS).</p> <p>Graph: Figure 3. Bland-Altman plots illustrate the comparison of measurements obtained from P and G across multiple conditions and tasks for the area's results. Each plot represents the difference between the measurements from the two devices against their average, with reference lines denoting the mean difference and limits of agreement. Each dot corresponds to a single subject. The three trials for each foot position were averaged to obtain a single value. The three different colors correspond to the limits shown in Table 4. Panels a, b, and c show the results for the F condition, while d, e, and f for the BO, in three different foot positions.</p> <p>Table 4. Bland-Altman Analysis of agreement between P and G for area's results. The mean difference, SD of differences, and limits of agreement are provided between the two devices. The analysis provides insight into the level of agreement and potential sources of variability between the measurement methods. The three different colors correspond to the color shown in Figure 3.</p> <p> <ephtml> <table><thead><tr><td /><td>P_BS; G_BS</td><td>P_TS; G_TS</td><td>P_SS; G_SS</td></tr><tr><td>Bias & Limits</td><td>Point value</td><td>Lower 95% CI</td><td>Upper 95% CI</td><td>Point value</td><td>Lower 95% CI</td><td>Upper 95% CI</td><td>Point value</td><td>Lower 95% CI</td><td>Upper 95% CI</td></tr></thead><tbody><tr><td><bold>Floor</bold></td></tr><tr><td>Mean difference + 1.96 SD</td><td>518.653</td><td>296.828</td><td>740.478</td><td>2122.071</td><td>1261.674</td><td>2982.468</td><td>1692.691</td><td>598.418</td><td>2786.963</td></tr><tr><td>Mean difference</td><td>−245.037</td><td>−373.108</td><td>−116.966</td><td>−840.068</td><td>−1336.819</td><td>−343.318</td><td>−2074.625</td><td>−2706.404</td><td>−1442.846</td></tr><tr><td>Mean difference − 1.96 SD</td><td>−1008.727</td><td>−1230.552</td><td>−786.902</td><td>−3802.207</td><td>−4662.604</td><td>−2941.81</td><td>−5841.941</td><td>−6936.213</td><td>−4747.668</td></tr><tr><td><bold>BOSU®</bold></td></tr><tr><td>Mean difference + 1.96 SD</td><td>2263.429</td><td>829.827</td><td>3697.031</td><td>3953.827</td><td>1642.041</td><td>6265.613</td><td>4000.088</td><td>1958.253</td><td>6041.923</td></tr><tr><td>Mean difference</td><td>−2672.116</td><td>−3499.806</td><td>−1844.425</td><td>−4005.093</td><td>−5339.803</td><td>−2670.383</td><td>−3029.456</td><td>−4208.31</td><td>−1850.602</td></tr><tr><td>Mean difference − 1.96 SD</td><td>−7607.66</td><td>−9041.262</td><td>−6174.058</td><td>−11964.01</td><td>−14275.798</td><td>−9652.227</td><td>−10059</td><td>−12100.836</td><td>−8017.166</td></tr></tbody></table> </ephtml> </p> <p>4 Bipedal Standing (BS); Confidence Interval (CI); GYKO (G); Force Platform (P); Single Standing (SS); Tandem Standing (TS).</p> <hd id="AN0182438457-8">Results</hd> <p>Results of the test and retest for both devices are shown in Table 1 (P) and Table 2 (G).</p> <p>The <emph>test-retest</emph> ICC for P ranged from <emph>moderate</emph> to <emph>good</emph> except for six parameters that resulted <emph>poor</emph> (four assessed in TS, one in BS above the BO and one in TS above the F). In detail, 42/78 parameters/conditions result <emph>moderate</emph>, and 30/78 <emph>good</emph>. In general, the lower and the upper ICC bounds range from <emph>poor</emph> (lower value 0.070) to <emph>excellent</emph> (upper value 0.920), with an ICC mean equal to 0.683, indicating <emph>moderate</emph> reliability.</p> <p>The <emph>test-retest</emph> ICC for G results were consistently <emph>moderate</emph> or <emph>good</emph> except for five parameters that were <emph>poor</emph> (three assessed in BS above the F, one in BS and one in SS above the BO). In detail, 49/78 parameters/conditions result <emph>moderate</emph>, and 24/78 <emph>good</emph>. In general, the lower and the upper ICC bounds range from <emph>poor</emph> (lower value 0.040) to <emph>excellent</emph> (upper value 0.921), with an ICC mean equal to 0.687, also in this case indicating <emph>moderate</emph> reliability. In Figure 2, the violin plots for the selected indices are reported for both devices (P and G) and over the two surfaces (F and BO).</p> <p>Tables 1 and 2 also present the SEM, which expresses absolute measurement reliability. In general, SEM<subs>%</subs> for P ranged from 7% to 41% (by taking into account all the indices), while, for G, it ranged from 11% to 47%.</p> <p>For all analyzed variables, MDC<subs>95%</subs> values ranged from 21% to 114% for P. For G, the values ranged from 30% to 132%. These results, when compared with those of Jaworski et al. ([<reflink idref="bib16" id="ref48">16</reflink>]), are consistent (i.e. Length_AP: SEM = 37.49 vs. 38.71; SEM<subs>%</subs> = 14.07% vs. 15.11%; MDC<subs>95</subs> = 103.91 vs. 107.31; MDC<subs>95%</subs> = 39.01% vs. 41.88%). In general, the data analysis concerning MDC<subs>95</subs> and ICC revealed high values at <emph>good</emph> and satisfactory measurement reliability, both for P and G.</p> <p>Because the <emph>test-retest reliability</emph> for both instruments (P and G) showed <emph>moderate reliability</emph>, the averaged values among test and retest (Table 3) were calculated and then used in order to assess the <emph>inter-rater reliability</emph> (G vs. P).</p> <p>Our data showed <emph>poor reliability</emph> for 57/78 parameters, and <emph>moderate</emph> for 18/78. Only 3/78 reached <emph>good reliability</emph> (all assessed in SS, two above the BO and one above the F). In general, the lower and the upper ICC bounds range from <emph>poor</emph> (lower value −0.162) to <emph>excellent</emph> (upper value 0.911), with an ICC mean equal to 0.338, indicating <emph>poor</emph> reliability. About the RMSE, the value for each single parameter/condition is reported in Table 3 with a grand mean equal to 342.5. The Mean Difference, again reported in Table 3 with the value for each single parameter/condition, showed a grand mean equal to 100.2.</p> <p>Figure 3 reports the Bland-Altman plots for the area of F and BO in the three-foot positions to provide a simple yet powerful graphical tool for comparing P and G (other plots are available in "Supplementary Material"). Table 4 reported the mean and the mean ± 1.96 SD. Together, they showed a large distribution of points across the plot, suggesting the presence of a substantial variability or inconsistency between the measurements obtained from the two devices. The spread indicates that the differences between the two methods vary widely across the range of measurements.</p> <hd id="AN0182438457-9">Discussion</hd> <p>We measured the <emph>test-retest</emph> and the <emph>inter-rater reliability</emph> of both a force platform with strain gauge transducers and a wearable IMU positioned at the lumbar level through different stable and unstable conditions and over various foot positions. The main findings were that: 1) both force platform and GYKO showed <emph>good/moderate test-retest reliability</emph> for the majority of the investigated indices; 2) if the device GYKO was compared to the "gold standard" force plate, the <emph>inter-rater reliability</emph> showed lower values for almost all parameters, which are interpreted as <emph>poor</emph>.</p> <p>The devices' <emph>test-retest</emph> and <emph>inter-rater reliability</emph> are mandatory to explore both usefulness and validity compared to the "gold standard." Sure enough, the literature has investigated wearable IMU sensors for postural assessment in biomechanics (Ancillao et al., [<reflink idref="bib4" id="ref49">4</reflink>]; Liang et al., [<reflink idref="bib21" id="ref50">21</reflink>]) and in training fields (Clemente et al., [<reflink idref="bib7" id="ref51">7</reflink>]), as well as over different populations (Ghislieri et al., [<reflink idref="bib12" id="ref52">12</reflink>]; Noamani et al., [<reflink idref="bib30" id="ref53">30</reflink>]). However, there are dozens of wearable IMUs, each with different characteristics.</p> <p>About the GYKO wearable sensor, previous studies have investigated the absolute and relative reliability of several measures of static postural stability (Jaworski et al., [<reflink idref="bib15" id="ref54">15</reflink>], [<reflink idref="bib16" id="ref55">16</reflink>]). In the study of Jaworski et al. ([<reflink idref="bib16" id="ref56">16</reflink>]), some postural outcomes have been investigated by positioning the GYKO at the scapular level (T1-T2) in an upright position, with eyes open for 30 s and repeating the trial test with the same experimental approach after one week. Most of the reliability indices calculated in this study were considered <emph>poor</emph> to <emph>good</emph>, with ICC values ranging from 0.31 to 0.75. Similar results were obtained in another research from the same group, with ICC values ranging from 0.62 to 0.70 for static tests performed on the dominant limb (Jaworski et al., [<reflink idref="bib15" id="ref57">15</reflink>]). However, the studies mentioned evaluated and validated <emph>test-retest reliability</emph> but were unable to verify <emph>inter-rater reliability</emph> with the "gold standard" device.</p> <p>Our study aimed to address this gap by investigating both changes in foot positions as well as above different surfaces. Furthermore, in this study, we have adopted Jaworski's suggestion to place the sensor at the lumbar level and to assess both men and women (Jaworski et al., [<reflink idref="bib16" id="ref58">16</reflink>]). The results regarding <emph>test-retest reliability</emph> showed an average ICC of 0.683 for the force plate and 0.687 for GYKO, demonstrating <emph>moderate reliability</emph>. Our findings about ICC for force platform matched exactly with <emph>test-retest reliability</emph> highlighted by Robbins et al. ([<reflink idref="bib35" id="ref59">35</reflink>]) inasmuch the average ICC for all parameters assessed in double leg stance, without perturbations and with eyes opened, corresponds to 0.684. In addition, this trend of slightly higher ICC values in GYKO has been previously demonstrated by Jaworski et al. ([<reflink idref="bib16" id="ref60">16</reflink>]) when comparing their ICC values with those in the study by Robbins et al. ([<reflink idref="bib35" id="ref61">35</reflink>]), which also supports our findings.</p> <p>Consequently, the absolute reliability of measurements should also be considered (Ghislieri et al., [<reflink idref="bib12" id="ref62">12</reflink>]). To achieve this, calculating SEM, MDC, RMSE and Mean Difference is necessary to understand better the levels of errors associated with the analyzed variables. It is important to note that even with significant inter-individual variability, high ICC values can be obtained despite low absolute reliability. Therefore, a higher SEM implies lower absolute test reliability and accuracy of the results (Liang et al., [<reflink idref="bib21" id="ref63">21</reflink>]). In our research, the average SEM<subs>%</subs> for all variables for GYKO was 23%, indicating good absolute measurement reliability. SEM values were also utilized to determine the MDC, which represents the minor change needed to distinguish actual change from the change caused by result variability or measurement errors.</p> <p>Consequently, evaluating the MDC for each variable characterizing postural stability offers insights into measurement errors. Indeed, this parameter has to be considered when determining the smallest significant changes expected between two consecutive measurements. Our results showed an MDC<subs>95%</subs> mean of about 64% by utilizing the GYKO sensor.</p> <p>The RMSE quantifies the precision with which an instrument measures a variable compared to the actual values. A lower RMSE indicates greater precision in predicting values relative to the actual data. These results can be used for subsequent comparisons between other devices or experimental conditions, as the instrument with the lowest RMSE might be preferable. The Mean Difference between G and P showed that, on average, G measures higher values than P. This difference may indicate a systematic variation in results between the two devices, primarily due to the type of sensor used in the detection system or device position. It is crucial to consider these differences when selecting a device for precise measurements, especially, for example, in research contexts where accuracy is essential. However, it is also important to consider other factors, such as ease of use and cost, that should be crucial in a clinical context.</p> <p>This is the first study investigating the <emph>inter-rater reliability</emph> of GYKO compared to the force platform. Ghislieri et al. ([<reflink idref="bib12" id="ref64">12</reflink>]) reported that out of 47 studies, only ten (21%) compared the results with the "gold standard." Our results showed <emph>poor reliability</emph> among devices; such a trend could be justified that the portable, less expensive, small device is not suitable if compared to the "gold standard." In addition, this pattern is also clearly evident by looking at the dispersion of data reported in the violin plots (Figure 2). As expected, the data collected by the force platform have significantly lower dispersions compared to those of GYKO. This difference is justifiable due to the concept of the inverted pendulum since GYKO is able to detect accelerations at the lumbar level while the force platform is directly connected from the base of support (Morasso et al., [<reflink idref="bib27" id="ref65">27</reflink>]).</p> <hd id="AN0182438457-10">Conclusion</hd> <p>The <emph>test-retest reliability</emph> assessed for the two devices showed, in general, <emph>moderate reliability</emph> assessed through the ICC. However, the <emph>inter-rater reliability</emph> showed <emph>poor reliability</emph> when compared to the force platform and the inertial wearable sensor. From a practical point of view, GYKO appears to be a convenient, less expensive, and portable field tool with high consistency between multiple measurements. However, its implementation for postural assessments in standing positions above stable and unstable surfaces with different foot positions must be considered with caution, especially if considering parameters such as SEM, MDC, RMSE and Mean Difference, which, when considered collectively, demonstrate better accuracy for the data collected with P compared to G.</p> <p>These results showed that GYKO is a reliable and user-friendly device for field/clinical assessment, but its use for research purposes must be considered with caution.</p> <hd id="AN0182438457-11">List of abbreviations</hd> <p></p> <p>• AP</p> <p></p> <ulist> <item> Antero-Posterior</item> <p></p> </ulist> <p>• BO</p> <p></p> <ulist> <item> Bosu®</item> <p></p> </ulist> <p>• BS</p> <p></p> <ulist> <item> Bipedal Standing</item> <p></p> </ulist> <p>• CI</p> <p></p> <ulist> <item> Confidence Interval</item> <p></p> </ulist> <p>• CoM</p> <p></p> <ulist> <item> Centre of Mass</item> <p></p> </ulist> <p>• CoP</p> <p></p> <ulist> <item> Centre of Pressure</item> <p></p> </ulist> <p>• G</p> <p></p> <p>• GYKO</p> <p></p> <p>• ICC</p> <p></p> <ulist> <item> Intraclass Correlation Coefficient</item> <p></p> </ulist> <p>• IMU</p> <p></p> <ulist> <item> Inertial Measurement Unit</item> <p></p> </ulist> <p>• MDC</p> <p></p> <ulist> <item> Minimal Detectable Change</item> <p></p> </ulist> <p>• ML</p> <p></p> <ulist> <item> Medio-Lateral</item> <p></p> </ulist> <p>• P</p> <p></p> <ulist> <item> Force Platform</item> <p></p> </ulist> <p>• RMS</p> <p></p> <ulist> <item> Root Mean Square</item> <p></p> </ulist> <p>• RMSE</p> <p></p> <ulist> <item> Root Mean Square Error</item> <p></p> </ulist> <p>• SEM</p> <p></p> <ulist> <item> Standard Error of Measurement</item> <p></p> </ulist> <p>• SS</p> <p></p> <ulist> <item> Single Standing</item> <p></p> </ulist> <p>• TS</p> <p></p> <ulist> <item> Tandem Standing</item> </ulist> <hd id="AN0182438457-12">Limits and future perspectives</hd> <p>This study was conducted on a population of healthy adults, and the results obtained may differ with children and/or elderly individuals. Furthermore, the values of SEM and MDC should be considered, which, although in line with the literature, are especially important in the context of evaluation (i.e. pre vs. post intervention or in clinical assessment). For example, on average, the SEM values for G are higher than those for P (SEM<subs>%</subs> = 23% vs. 15%, respectively). This indicates that the sample mean measured by P is a relatively precise estimate compared to G. Indeed, a high SEM indicates greater variability in the estimate. Similarly, the MDC values are higher for G compared to P (MDC<subs>95%</subs> = 64% vs. 44%), implying that only larger changes are considered significant. These limits are corroborated also by the results obtained by RMSE and Mean Difference. Future research could help clarify the causes of these differences and improve consistency between devices. Lastly, these results are valid for the specific inertial sensor of GYKO but are not applicable to other IMUs. Although the novelty of this study is the comparison with the gold standard in different stability/instability conditions, there remain a number of areas where further studies are necessary to confirm our results. Indeed, future studies should aim to evaluate the use of IMUs in comparison with common clinical/functional tests used to assess balance in healthy subjects and those with pathologies (Nguyen et al., [<reflink idref="bib29" id="ref66">29</reflink>]; Ting et al., [<reflink idref="bib36" id="ref67">36</reflink>]). Future research should address these aspects by comparing the "gold standard" with other dedicated instrumentations.</p> <hd id="AN0182438457-13">Disclosure statement</hd> <p>No potential conflict of interest was reported by the author(s).</p> <hd id="AN0182438457-14">Author contributions</hd> <p>SD, FN, and CT conceived the study. SD, FN, FG, and DC collect the data. SD and FN analyzed and interpreted the data. SD wrote, and FN revised the original draft manuscript. FS and CT final draft review and supervision. All the authors have read and agreed to the published version of the manuscript.</p> <hd id="AN0182438457-15">Data availability statement</hd> <p>The data used to support the findings of this study are available from the corresponding author upon request.</p> <hd id="AN0182438457-16">Supplementary material</hd> <p>Supplemental data for this article can be accessed online at https://doi.org/10.1080/1091367X.2024.2403564.</p> <hd id="AN0182438457-17">Institutional review board statement</hd> <p>The experimental protocol was approved by the Ethical Advisory Committee (University of Verona – approval n. 37. R1/2023), and the study was conducted in accordance with the Helsinki Declaration.</p> <hd id="AN0182438457-18">Informed consent statement</hd> <p>Informed consent was obtained from all subjects involved in the study, by explaining them the objectives and procedures of the experimental protocol.</p> <ref id="AN0182438457-19"> <title> References </title> <blist> <bibl id="bib1" idref="ref2" type="bt">1</bibl> <bibtext> Agostini, V., Chiaramello, E., Bredariol, C., Cavallini, C., & Knaflitz, M. (2011). Postural control after traumatic brain injury in patients with neuro-ophthalmic deficits. Gait & posture, 34 (2), 248 – 253. https://doi.org/10.1016/j.gaitpost.2011.05.008</bibtext> </blist> <blist> <bibl id="bib2" idref="ref5" type="bt">2</bibl> <bibtext> Agostini, V., Chiaramello, E., Canavese, L., Bredariol, C., & Knaflitz, M. (2013). Postural sway in volleyball players. 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Gait & Posture, 33 (4), 594 – 599. https://doi.org/10.1016/j.gaitpost.2011.01.015</bibtext> </blist> </ref> <aug> <p>By Samuel D'Emanuele; Francesca Nardello; Fabrizio Garau; Diego Campaci; Federico Schena and Cantor Tarperi</p> <p>Reported by Author; Author; Author; Author; Author; Author</p> </aug> <nolink nlid="nl1" bibid="bib31" firstref="ref1"></nolink> <nolink nlid="nl2" bibid="bib23" firstref="ref4"></nolink> <nolink nlid="nl3" bibid="bib13" firstref="ref9"></nolink> <nolink nlid="nl4" bibid="bib28" firstref="ref10"></nolink> <nolink nlid="nl5" bibid="bib12" firstref="ref11"></nolink> <nolink nlid="nl6" bibid="bib24" firstref="ref12"></nolink> <nolink nlid="nl7" bibid="bib25" firstref="ref13"></nolink> <nolink nlid="nl8" bibid="bib26" firstref="ref14"></nolink> <nolink nlid="nl9" bibid="bib14" firstref="ref16"></nolink> <nolink nlid="nl10" bibid="bib15" firstref="ref17"></nolink> <nolink nlid="nl11" bibid="bib22" firstref="ref18"></nolink> <nolink nlid="nl12" bibid="bib38" firstref="ref19"></nolink> <nolink nlid="nl13" bibid="bib11" firstref="ref21"></nolink> <nolink nlid="nl14" bibid="bib16" firstref="ref22"></nolink> <nolink nlid="nl15" bibid="bib17" firstref="ref23"></nolink> <nolink nlid="nl16" bibid="bib20" firstref="ref25"></nolink> <nolink nlid="nl17" bibid="bib33" firstref="ref26"></nolink> <nolink nlid="nl18" bibid="bib34" firstref="ref27"></nolink> <nolink nlid="nl19" bibid="bib37" firstref="ref30"></nolink> <nolink nlid="nl20" bibid="bib18" firstref="ref33"></nolink> <nolink nlid="nl21" bibid="bib10" firstref="ref34"></nolink> <nolink nlid="nl22" bibid="bib32" firstref="ref36"></nolink> <nolink nlid="nl23" bibid="bib19" firstref="ref37"></nolink> <nolink nlid="nl24" bibid="bib21" firstref="ref50"></nolink> <nolink nlid="nl25" bibid="bib30" firstref="ref53"></nolink> <nolink nlid="nl26" bibid="bib35" firstref="ref59"></nolink> <nolink nlid="nl27" bibid="bib27" firstref="ref65"></nolink> <nolink nlid="nl28" bibid="bib29" firstref="ref66"></nolink> <nolink nlid="nl29" bibid="bib36" firstref="ref67"></nolink>
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  Group: Ti
  Data: Test-Retest and Inter-Rater Reliability for Selected Outcomes from a Wearable 3D Inertial Sensor over Different Stable and Unstable Postural Conditions: A Validation Study
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  Data: <searchLink fieldCode="AR" term="%22Samuel+D'Emanuele%22">Samuel D'Emanuele</searchLink> (ORCID <externalLink term="https://orcid.org/0000-0001-6232-9870">0000-0001-6232-9870</externalLink>)<br /><searchLink fieldCode="AR" term="%22Francesca+Nardello%22">Francesca Nardello</searchLink> (ORCID <externalLink term="https://orcid.org/0000-0001-8942-3920">0000-0001-8942-3920</externalLink>)<br /><searchLink fieldCode="AR" term="%22Fabrizio+Garau%22">Fabrizio Garau</searchLink> (ORCID <externalLink term="https://orcid.org/0009-0007-1564-2347">0009-0007-1564-2347</externalLink>)<br /><searchLink fieldCode="AR" term="%22Diego+Campaci%22">Diego Campaci</searchLink> (ORCID <externalLink term="https://orcid.org/0009-0008-4238-2146">0009-0008-4238-2146</externalLink>)<br /><searchLink fieldCode="AR" term="%22Federico+Schena%22">Federico Schena</searchLink> (ORCID <externalLink term="https://orcid.org/0000-0002-2052-5117">0000-0002-2052-5117</externalLink>)<br /><searchLink fieldCode="AR" term="%22Cantor+Tarperi%22">Cantor Tarperi</searchLink> (ORCID <externalLink term="https://orcid.org/0000-0002-7208-9484">0000-0002-7208-9484</externalLink>)
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  Data: <searchLink fieldCode="SO" term="%22Measurement+in+Physical+Education+and+Exercise+Science%22"><i>Measurement in Physical Education and Exercise Science</i></searchLink>. 2025 29(1):98-112.
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  Data: Routledge. Available from: Taylor & Francis, Ltd. 530 Walnut Street Suite 850, Philadelphia, PA 19106. Tel: 800-354-1420; Tel: 215-625-8900; Fax: 215-207-0050; Web site: http://www.tandf.co.uk/journals
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  Data: 15
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  Data: 2025
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  Data: Journal Articles<br />Reports - Research
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  Label: Descriptors
  Group: Su
  Data: <searchLink fieldCode="DE" term="%22Human+Posture%22">Human Posture</searchLink><br /><searchLink fieldCode="DE" term="%22Measurement+Equipment%22">Measurement Equipment</searchLink><br /><searchLink fieldCode="DE" term="%22Interrater+Reliability%22">Interrater Reliability</searchLink><br /><searchLink fieldCode="DE" term="%22Measurement+Techniques%22">Measurement Techniques</searchLink><br /><searchLink fieldCode="DE" term="%22Young+Adults%22">Young Adults</searchLink><br /><searchLink fieldCode="DE" term="%22Test+Reliability%22">Test Reliability</searchLink><br /><searchLink fieldCode="DE" term="%22Validity%22">Validity</searchLink><br /><searchLink fieldCode="DE" term="%22Foreign+Countries%22">Foreign Countries</searchLink>
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  Data: <searchLink fieldCode="DE" term="%22Italy%22">Italy</searchLink>
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  Data: 10.1080/1091367X.2024.2403564
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  Data: 1091-367X<br />1532-7841
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  Label: Abstract
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  Data: The agreement between a wearable inertial sensor (GYKO, G) and the force platform (P) was assessed by evaluating "test-retest" and "inter-rater reliability." Thirty-eight subjects were enrolled; the selected indices of balance were investigated over foot positions and (un)stable conditions. Intraclass correlation coefficient (ICC), standard error of measurement (SEM[subscript %]) and minimal detectable change (MDC[subscript95%]) were computed. For G, ICC bounds range from "poor" to "excellent" (0.040 ÷ 0.921), mean of 0.687 (= "moderate reliability"). Regarding P, ICC ranges from "poor" to "excellent" (0.070 ÷ 0.920), mean of 0.683 (= "moderate reliability"). For G, SEM[subscript %] ranges from 11% to 47%; MDC[subscript95%] from 30% to 132%. Concerning P, SEM[subscript %] ranges from 7% to 41%; MDC[subscript95%] from 21% to 114%. Finally, the "inter-rater reliability" ICC by comparing devices ranges from "poor" to "excellent" (-0.162 ÷ 0.911), mean of 0.338 (= "poor reliability"). GYKO appears to be a convenient tool with high consistency among multiple measurements but for specific clinic/research purposes.
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  Data: 2025
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      – SubjectFull: Human Posture
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      – SubjectFull: Measurement Equipment
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      – SubjectFull: Interrater Reliability
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      – TitleFull: Test-Retest and Inter-Rater Reliability for Selected Outcomes from a Wearable 3D Inertial Sensor over Different Stable and Unstable Postural Conditions: A Validation Study
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