Myofascial force transmission between the calf and the dorsal thigh is dependent on knee angle: an ultrasound study

Abstract

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: R2 = 0.18, p = 0.001; flexed: R2 = 0.17, p = 0.002) as well as (2) SM soft tissue displacement and ankle range of motion (extended: R2 = 0.103, p = 0.017; flexed: R2 = 0.095, p = 0.022). Our results further strengthen the evidence that local stretching induces a force transmission to neighboring muscles. Resulting remote exercise effects such as increased range of motion, seem to depend on the stiffness of the continuity.Trial registration: DRKS (Deutsches Register Klinischer Studien), registration number DRKS00024420, first registered 08/02/2021, https://drks.de/search/de/trial/DRKS00024420.

Effect of different isometric trunk extension intensities on the muscle stiffness of the lumbar and lower limbs

“…In addition, anatomical studies found that there was a fascial connection between the gastrocnemius muscle and the ST ( Wilke et al, 2016 ). These non-local changes may be the result of coordinated muscle contractions along the kinetic chain, and the extent of long-distance motion effects caused by coordinated muscle contractions may depend on the stiffness of the continuity of the affected tissue, studying the correlation of stiffness changes can be used as an alternative test of force transmission ( Mohr et al, 2023 ). It can be seen from the above situation that there is tissue continuity in the major muscle groups activated during IPTE training with different contraction strengths, and there is a coordinated contraction of the kinetic chain between ES, hamstring, and gastrocnemius, which is mainly manifested as ES, ST, and LG, which is consistent with the results of our previous experiment ( Zhang et al, 2023 ).…”