Subject terms
REGRESSION
A recent in-vivo experiment has shown that force can be transmitted between the gastrocnemius and the hamstring muscles due to a direct tissue continuity. However, it remains unclear if this mechanical interaction is affected by the stiffness of the structural connection. This study therefore aimed to investigate the impact of the knee angle on myofascial force transmission across the dorsal knee. A randomized, cross-over study was performed, including n = 56 healthy participants (25.36 ± 3.9 years, 25 females). On two separate days, they adopted a prone position on an isokinetic dynamometer (knee extended or 60° flexed). In each condition, the device moved the ankle three times from maximal plantarflexion to maximal dorsal extension. Muscle inactivity was ensured using EMG. High-resolution ultrasound videos of the semimembranosus (SM) and the gastrocnemius medialis (GM) soft tissue were recorded. Maximal horizontal tissue displacement, obtained using cross-correlation, was examined as a surrogate of force transmission. SM tissue displacement was higher at extended (4.83 ± 2.04 mm) than at flexed knees (3.81 ± 2.36 mm). Linear regression demonstrated significant associations between (1) SM and GM soft tissue displacement (extended: RTrial registration: DRKS (Deutsches Register Klinischer Studien), registration number DRKS00024420, first registered 08/02/2021, Open Access funding enabled and organized by Projekt DEAL.