Graft-Specific Neuromuscular Responses and EMG Activities During Running Before and After Running-Induced Fatigue in Individuals with ACL Reconstruction.

Authors

Heidar Sajedi, Mahsa Habibi, AmirAli Jafarnezhadgero, Ebrahim Piri, Kate E Webster, Valdeci Carlos Dionisio

Published in

Sensors (Basel, Switzerland). Volume 26. Issue 15. Aug 03, 2026. Epub Aug 03, 2026.

Abstract

Fatigue during intense activity challenges the neuromuscular system and can reveal deficits not evident during lower-demand functional tasks. In individuals with anterior cruciate ligament reconstruction (ACLR), differences in graft source may be associated with graft-specific neuromuscular adaptations. Although fatigue-related neuromuscular deficits after ACLR have been reported, few studies have examined whether these responses differ according to graft type during running. This study investigated the effects of running-induced fatigue on lower-limb muscle activity during the stance phase in ACLR patients with different graft types, compared with healthy controls.
Fifty-three active males were allocated into four groups: single-bundle hamstring tendon (SB-HT), double-bundle hamstring tendon (DB-HT), allograft, and healthy controls. Participants completed a treadmill-based fatigue protocol that was terminated when they reached a Borg score > 17, which served as the primary criterion for confirming a high level of perceived fatigue. Heart rate ≥ 85% of estimated maximum heart rate was recorded as a complementary physiological indicator of high-intensity exertion. Electromyography (EMG) amplitudes of eight lower-limb muscles were recorded during the early and late stance phases of running, before and after fatigue. A two-way mixed-model ANOVA evaluated the effects of graft type and fatigue condition.
Fatigue reduced semitendinosus (p = 0.042, ηp² = 0.091) and gluteus medius (p < 0.001, ηp² = 0.442) activation during early stance regardless of group. Late-stance group effects were significant for the tibialis anterior, gastrocnemius, rectus femoris, biceps femoris, semitendinosus, and gluteus medius (p ≤ 0.05). Across stance phases, the SB-HT group showed greater hamstring and gluteus medius activation than healthy controls (p = 0.003-0.041), while the allograft group showed greater tibialis anterior, gastrocnemius, and rectus femoris activation during late stance (p = 0.005-0.043). The only significant group × fatigue interaction was observed for vastus medialis (p = 0.002, ηp² = 0.279), reflecting a fatigue-related reduction in the DB-HT group.
Graft type was associated with distinct lower-limb EMG activation patterns during running after ACLR. Fatigue revealed a DB-HT-specific reduction in vastus medialis activation, while the allograft and SB-HT groups showed different compensatory activation profiles. These findings suggest that graft-specific neuromuscular adaptations during fatigue should be considered when developing rehabilitation protocols to improve functional stability and future joint health.

PMID:
42590679
Bibliographic data and abstract were imported from PubMed on 13 Aug 2026.

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