Fatigue-induced changes in hamstrings’ active muscle stiffness: effect of contraction type and implications for strain injuries

Abstract

Purpose Hamstring strain injuries may occur due to differential fatigue and compromised mechanical properties among the hamstring muscles. We examined (1) the effect of fatigue on hamstrings active muscle stiffness, and (2) whether contraction type affects active muscle stiffness changes during a submaximal fatiguing task. Methods Nine healthy males completed 99 submaximal knee flexions in isometric (ISO), concentric (CON), and eccentric (ECC) conditions. We measured the knee flexor maximal voluntary torque (MVT) (pre/post), shear wave velocity (SWV) during contraction and transverse relaxation times (T2) (pre/post) in biceps femoris long head (BFlh), semitendinosus (ST), and semimembranosus (SM) muscles. Results MVT decreased substantially after all conditions (− 18.4 to − 33.6%). The average relative torque sustained during the task was lower in CON than ISO and ECC, but absolute torque was similar. SWV interindividual responses were highly variable across muscles and contraction types. On average, BFlh SWV tended to increase in ISO (0.4 m/s, 4.5%, p = 0.064) but decreased in ECC condition (− 0.8 m/s, − 7.7%, p < 0.01). ST SWV decreased in CON (− 1.1 m/s, − 9.0%, p < 0.01), while it remained unchanged in ISO and ECC. SM SWV decreased in CON (− 0.8 m/s, − 8.1%, p < 0.01), but it was unaffected in ISO and variable in ECC. Conclusion Fatigue has a differential effect on the mechanical properties of the constituent hamstring muscles, as measured with shear wave elastography, depending upon contraction type. We found preliminary evidence that BFlh is more fatigued than ST or SM during eccentric contractions, which may explain its susceptibility to strain injuries.

Acute fatigue-induced alterations in hamstring muscle properties after repeated Nordic hamstring exercises

“…Their study demonstrated that hamstring eccentric exercises using an isokinetic dynamometer may lead to an increase in stiffness post-exercise. On the other hand, our results also showed a significantly greater stiffness in the BFLH compared to the ST. Our findings are in line with Evangelidis et al, 47 who found the BFLH to be a more fatigable muscle compared to the ST or semimembranosus. Andonian et al 48 found that greater stiffness after strenuous exercise may be related to altered extracellular water volume.…”

“… 49 Moreover, greater mechanical alterations in BFLH compared with ST might be related to the fact that BFLH experiences the greatest strain compared to other muscles in the posterior thigh. 47 A research study performed by Seymore et al 21 showed that NHE training did not significantly affect muscle fascicle length, stiffness, or eccentric hamstring strength. Noticeable changes in muscles may be related to increased vascularity resulting from greater muscle activity during acute fatigue.…”

“…The results showed an increase in muscle stiffness immediately post-NHE compared to baseline. Evangelidis et al 47 reported a significant impact of fatigue on the mechanical properties of hamstring muscles, measured as shear wave velocity. Their study demonstrated that hamstring eccentric exercises using an isokinetic dynamometer may lead to an increase in stiffness post-exercise.…”

Assessment of Muscle Stiffness Using the MyotonPro: Effects of Fatigue on Vastus Lateralis and Medialis Muscles

“…Maximal muscle fatigue induces heightened muscle stiffness and muscle frequency, as observed in both dominant and non-dominant legs. This insight holds pivotal significance for rehabilitation and sports performance, indicating that fatigue elicits distinct effects on specific muscle groups [ 8 ]. Rehabilitation programs and training protocols may necessitate tailored considerations for these distinctions to augment recovery and optimize performance [ 31 ].…”

“…Furthermore, Evangelidis et al demonstrated that muscle fatigue significantly impacts the stiffness of the biceps femoris long-head muscle more than the semitendinosus and semimembranosus muscles, providing insight into the increased vulnerability to strain injuries within this muscle group [ 8 ]. Additionally, in the context of rehabilitation following Rotator Cuff tendinopathy, there is a manifestation of reduced tendon stiffness [ 9 ].…”