Résumé:
Background: Return to running (RTR) after anterior cruciate ligament
reconstruction (ACL-R) remains challenging due to persistent neuromuscular
deficits. This study examines gastrocnemius activation and running
biomechanics in ACL-R patients.
Methods: Fifteen ACL-R patients and fifteen healthy controls were assessed
using surface electromyography during isometric testing and treadmill running
(10 km.h−1). Spatiotemporal parameters, including ground contact time, flight
time, step width, cadence, stride length, and vertical stiffness, were analyzed.
Results: ACL-R patients exhibited lower gastrocnemius activation during
isometric testing (medial: 48.5% vs. 55.9% MVIC, p = 0.01; lateral: 42.1% vs.
47.5% MVIC, p = 0.03) and during running (medial: 45.2% vs. 53.1% MVIC,
p < 0.01; lateral: 39.7% vs. 44.8% MVIC, p = 0.04). They also demonstrated
altered running biomechanics, including longer ground contact time (0.29 vs.
0.26 s, p = 0.02, d = − 0.5), shorter stride length (1.32 vs. 1.41 m, p = 0.03,
d = 0.9), reduced vertical stiffness (21.8 vs. 25.6 kN.m−1, p = 0.03, d = 0.5), and
slightly increased step width (0.14 vs. 0.13 m, p = 0.05, d = 0.4). A significant
negative correlation was observed between medial gastrocnemius activation
during running and ground contact time (rs = −0.56, p = 0.02, ES = −0.6).
Lateral gastrocnemius activation was positively correlated with stride length
(rs = 0.49, p = 0.03, ES = 0.5), and medial gastrocnemius activation showed a
moderate positive correlation with vertical stiffness (rs = 0.52, p = 0.04,
ES = 0.5). Cadence did not show a statistically significant correlation with
either medial or lateral gastrocnemius activation (rs = 0.36, p = 0.08, ES = 0.4
and rs = 0.45, p = 0.09, ES = 0.4, respectively).
Conclusion: Gastrocnemius dysfunction persists after ACL-R, affecting running
mechanics. These findings suggest that current rehabilitation protocols may
need to incorporate plantar flexor training to optimize running mechanics
post-ACL-R.
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