Journal
JOURNAL OF APPLIED PHYSIOLOGY
Volume 125, Issue 4, Pages 1069-1079Publisher
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/japplphysiol.00133.2018
Keywords
hamstring; individual coordination; muscle endurance; muscle torque
Categories
Funding
- French Ministry of Research
- Institut Universitaire de France
Ask authors/readers for more resources
The torque-sharing strategies between synergistic muscles may have important functional consequences. This study involved two experiments. The first experiment (n = 22) aimed 1) to determine the relationship between the distribution of activation and the distribution of torque-generating capacity among the heads of the hamstring, and 2) to describe individual torque-sharing strategies and to determine whether these strategies are similar between legs. The second experiment (n = 35) aimed to determine whether the distribution of activation between the muscle heads affects endurance performance during a sustained submaximal knee flexion task. Surface electromyography (EMG) was recorded from biceps femoris (BF), semimembranosus (SM), and semitendinosus (ST) during submaximal isometric knee flexions. Torque-generating capacity was estimated by measuring muscle volume, fascicle length, pennation angle, and moment arm. The product of the normalized EMG amplitude and the torque-generating capacity was used as an index of muscle torque. The distributions of muscle activation and of torque-generating capacity were not correlated significantly (all P = 0.18). Thus, there was a torque imbalance between the muscle heads (ST torque = BF and SM torque; P = 0.001), the magnitude of which varied greatly between participants. A significant negative correlation was observed between the imbalance of activation across the hamstring muscles and the time to exhaustion (P = 0.001); i. e., the larger the imbalance of activation across muscles, the lower the muscle endurance performance. Torque-sharing strategies between the heads of the hamstrings are individual specific and related to muscle endurance performance. Whether these individual strategies play a role in hamstring injury remains to be determined. NEW & NOTEWORTHY The distribution of activation among the heads of the hamstring is not related to the distribution of torquegenerating capacity. The torque-sharing strategies within hamstring muscles vary greatly between individuals but are similar between legs. Hamstring coordination affects endurance performance; i. e., the larger the imbalance of activation across the muscle heads, the lower the muscle endurance.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available