Sub-symptom threshold aerobic exercise for patients with persisting post-concussion symptoms and exercise intolerance after mild traumatic brain injury – a study protocol with a nested feasibility study for a randomized controlled trial. - Valaas, Lars-Johan V.; Soberg, Helene L.; Rasmussen, Mari S.; Steenstrup, Sophie E.; Andelic, Nada; Kleffelgård, Ingerid (BMC Neurology, 2023)