hamstrings

Background: We assessed the effects of a 6-week, low-volume Nordic hamstring exercise (NHE) intervention on hamstring flexibility, muscle mechanical properties and eccentric and isometric isokinetic knee flexion strength in recreationally active adults. Methods: Eighteen recreationally active adults were randomized into an NHE intervention group (IG; n = 9; females/males: 3/6; mean ± SD, age: 24.1 ± 1.3 years) and control group (CG; n = 9; females/males: 5/4; mean ± SD, age: 23.5 ± 1.8 years). The NHE intervention involved a progressive, supplementary training program performed initially one (weeks 1 and 2) and then two times per week over a 6-week period. The number of repetitions per session increased from 15 to 36 repetitions/week. The CG maintained their usual exercise routine over the same period. Standard goniometry, myotonometry, and isokinetic dynamometry (60°/s) were used to measure hamstring flexibility, muscle properties and isometric and eccentric isokinetic strength prior to and five days following the intervention. Results: The Linear Mixed Methods analysis identified a significant group × time interactions for isometric torque (IG: +5% vs. CG: −12%, p = 0.022) and flexibility (IG: +1% vs. CG: +7%, p = 0.023). Peak eccentric torque (IG: +7% vs. CG: −7%, p = 0.053) and muscle mechanical properties remained unchanged over the intervention period. Conclusions: Six weeks of low-volume NHE training marginally improved isometric and eccentric hamstring strength in recreationally active adults without changing hamstring flexibility or mechanical properties. The findings may have important implications for performance enhancement and hamstring injury risk reduction during high-intensity recreational sports.

matched text: “hamstring”

This study aimed to establish a multimodal framework integrating cardiopulmonary exercise testing (CPET), surface electromyography (sEMG), and plantar kinetic assessment to characterize neuromuscular and mechanical fatigue responses during high-intensity treadmill exercise. Twenty healthy collegiate male athletes performed an incremental CPET followed by a supramaximal verification phase. Gas exchange, heart rate, and perceived exertion were continuously recorded. Bilateral sEMG activity from the rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius lateralis was analyzed for integrated EMG (iEMG), root mean square (RMS), and median frequency (MF). Pre- and post-exercise plantar kinetics were obtained using in-shoe pressure sensors to assess contact area, mean pressure, and vertical ground reaction force (VGRF). Plantar kinetics showed increased midfoot contact area (+12.3%, <i>P</i> = 0.01) and pressure (+10.8%, <i>P</i> = 0.03), along with elevated left-foot regional VGRF (<i>P</i> = 0.04), indicating side-specific post-exercise load redistribution. Although nominal correlations were observed between neuromuscular activation and post-exercise plantar loading, these associations did not remain statistically significant after false discovery rate (FDR) correction and should therefore be interpreted as exploratory. Rather than establishing a quantitative diagnostic threshold for fatigue, integrating cardiopulmonary, neuromuscular, and plantar kinetic measures contributes to a multidimensional characterization of fatigue-related adaptations beyond metabolic indicators alone. This multimodal framework illustrates how neural drive decline and mechanical load redistribution may co-occur under acute fatigue conditions, providing a structured approach for comprehensive fatigue profiling in athletic populations.

matched text: “biceps femoris”