Fatigue-Induced Changes in Knee-Extensor Mechanical Performance and Rectus Femoris Surface EMG During Repeated Isokinetic Knee Extensions.
- 1Biomechanics Laboratory, Faculty of Sport and Movement Sciences, Levinsky-Wingate Academic College (Wingate Campus), Netanya 4290200, Israel.
Abstract
Performance fatigability is characterized by a decline in the capacity to maintain force or power during sustained or repeated activity. This exploratory study quantified knee-extensor mechanical performance and rectus femoris surface electromyographic (sEMG) changes during repeated maximal isokinetic knee extensions and explored sex-related differences. Twenty-nine healthy adults (20 men, 9 women; 20-31 years) performed 30 maximal concentric knee extensions at 180°·s⁻¹. Mechanical outcomes were analyzed in all 29 participants, whereas rectus femoris sEMG outcomes were analyzed in 23 participants. Peak torque (PT) decreased by 32.75 ± 11.66% (adjusted p = 6.08 × 10⁻¹¹), work per repetition by 33.35 ± 11.97% (adjusted p = 2.12 × 10⁻¹¹), and mean frequency (MNF) by 23.44 ± 8.33% (adjusted p = 6.08 × 10⁻¹¹). RMS increased significantly from Start to End (adjusted p = 0.000639), with a mean FI-RMS of -17.12 ± 23.11%. FI-PT and FI-work were very strongly associated (ρ = 0.938, adjusted p = 3.71 × 10⁻¹³), whereas no association involving rectus femoris MNF or RMS remained statistically significant after Holm-Bonferroni correction. No statistically significant sex-related differences were detected. Repeated maximal knee extensions reduced mechanical performance and rectus femoris MNF while increasing RMS. FI summarizes Start-to-End change across the measured outcomes; its reliability and validity require further investigation.
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BibTeX
@article{peleg2026fatigueinduced,
title = {{Fatigue-Induced Changes in Knee-Extensor Mechanical Performance and Rectus Femoris Surface EMG During Repeated Isokinetic Knee Extensions.}},
author = {Smadar Peleg and Ophir Ravina and Eitan Shemy and Moshe Ayalon},
journal = {Muscles (Basel, Switzerland)},
year = {2026},
month = oct,
doi = {10.3390/muscles5040072},
url = {https://europepmc.org/article/MED/42924644},
note = {CC BY},
}
RIS
TY - JOUR
TI - Fatigue-Induced Changes in Knee-Extensor Mechanical Performance and Rectus Femoris Surface EMG During Repeated Isokinetic Knee Extensions.
AU - Smadar Peleg
AU - Ophir Ravina
AU - Eitan Shemy
AU - Moshe Ayalon
PY - 2026
DA - 2026/10/04
JO - Muscles (Basel, Switzerland)
DO - 10.3390/muscles5040072
UR - https://europepmc.org/article/MED/42924644
AB - Performance fatigability is characterized by a decline in the capacity to maintain force or power during sustained or repeated activity. This exploratory study quantified knee-extensor mechanical performance and rectus femoris surface electromyographic (sEMG) changes during repeated maximal isokinetic knee extensions and explored sex-related differences. Twenty-nine healthy adults (20 men, 9 women; 20-31 years) performed 30 maximal concentric knee extensions at 180°·s⁻¹. Mechanical outcomes were analyzed in all 29 participants, whereas rectus femoris sEMG outcomes were analyzed in 23 participants. Peak torque (PT) decreased by 32.75 ± 11.66% (adjusted p = 6.08 × 10⁻¹¹), work per repetition by 33.35 ± 11.97% (adjusted p = 2.12 × 10⁻¹¹), and mean frequency (MNF) by 23.44 ± 8.33% (adjusted p = 6.08 × 10⁻¹¹). RMS increased significantly from Start to End (adjusted p = 0.000639), with a mean FI-RMS of -17.12 ± 23.11%. FI-PT and FI-work were very strongly associated (ρ = 0.938, adjusted p = 3.71 × 10⁻¹³), whereas no association involving rectus femoris MNF or RMS remained statistically significant after Holm-Bonferroni correction. No statistically significant sex-related differences were detected. Repeated maximal knee extensions reduced mechanical performance and rectus femoris MNF while increasing RMS. FI summarizes Start-to-End change across the measured outcomes; its reliability and validity require further investigation.
SN - 2813-0413
ER -