Epimuscular myofascial force transmission from biarticular rectus femoris elongation increases shear modulus of monoarticular quadriceps muscles

Negligible epimuscular myofascial force transmission between the human rectus femoris and vastus lateralis muscles in passive conditions

“…Thus, there remains some uncertainty regarding the cause of the shear wave modulus changes in the soleus muscle. More recently, Yanase et al (2021) investigated how extremes of hip range of motion, which impose a greater stretch on the rectus femoris muscle, impact stiffness in the mono-articular vastus medialis and lateralis muscles. While they noted changes in muscle stiffness with changes in hip angle, the muscles were not fully relaxed during the experimental procedures, which may have impacted their measures of muscle stiffness.…”

“…This amount of muscle activity is likely sufficient to also impact measures of muscle stiffness. Thus, differences in the amount of muscle activity present when the hip was in different extreme ranges could, in theory, account for the differences observed by Yanase et al (2021).…”

“…However, due to the small size of the effect investigated and possible inaccuracies in shear-wave elastography measures (Ruby et al 2019;Sarabon et al 2019;Wang et al 2020;Kozinc and Sarabon 2020), it could be that the study by Freitas et al (2019) failed to detect epimuscular myofascial force transmission that was present. Recently, Yanase et al (2021) argued that Freitas et al (2019) did not sufficiently stretch the rectus femoris muscle. Thus, they conducted a similar experiment where the pelvis was fixed and the hip was positioned in more extreme ranges and observed differences in the passive stiffness of the vastus lateralis and medialis muscles.…”