Current evidence demonstrates similar effects of kilohertz-frequency and low-frequency current on quadriceps evoked torque and discomfort in healthy individuals: a systematic review with meta-analysis. - da Silva, Vinicius Zacarias Maldaner; Durigan, João Luiz Quaglioti; Arena, Ross; de Noronha, Marcos; Gurney, Burke; Cipriano, Gerson (Physiotherapy Theory & Practice, 2015)