Muscle Activation During Landing Before and After Fatigue in Individuals With or Without Chronic Ankle Instability.
BACKGROUND
Ankle instability is a common condition in physically active individuals. It often occurs during a jump landing or lateral motion, particularly when participants are fatigued.


OBJECTIVE
To compare muscle activation during a lateral hop prefatigue and postfatigue in individuals with or without chronic ankle instability (CAI).


METHODS
Cross-sectional study.


METHODS
Sports medicine research laboratory.


METHODS
A total of 32 physically active participants volunteered for the study. Sixteen participants with CAI (8 men, 8 women; age = 20.50 ± 2.00 years, height = 172.25 ± 10.87 cm, mass = 69.13 ± 13.31 kg) were matched with 16 control participants without CAI (8 men, 8 women; age = 22.00 ± 3.30 years, height = 170.50 ± 9.94 cm, mass = 69.63 ± 14.82 kg) by age, height, mass, sex, and affected side.


METHODS
Electromyography of the tibialis anterior, peroneus longus, gluteus medius, and gluteus maximus was measured before and after a functional fatigue protocol.


METHODS
Activation of 4 lower extremity muscles was measured 200 milliseconds before and after landing from a lateral hop.


RESULTS
We observed no interactions. The group main effects for the peroneus longus demonstrated higher muscle activation in the CAI group (52.89% ± 11.36%) than in the control group (41.12% ± 11.36%) just before landing the lateral hop (F1,30= 8.58, P = .01), with a strong effect size (d = 1.01). The gluteus maximus also demonstrated higher muscle activation in the CAI group (45.55% ± 12.08%) than in the control group (36.81% ± 12.08%) just before landing the lateral hop (F1,30= 4.19, P = .049), with a moderate effect size (d = 0.71). We observed a main effect for fatigue for the tibialis anterior, with postfatigue activation higher than prefatigue activation (F1,30= 7.45, P = .01). No differences were present between groups for the gluteus medius.


CONCLUSIONS
Our results support the presence of a centralized feed-forward neuromuscular alteration in patients with CAI, not only in the ankle-joint muscles but also in the proximal hip muscles. These results may have implications for rehabilitation programs in these patients.
Department of Physical Therapy and Athletic Training, Boston University, MA.
Kathryn A
KA
Webster
Department of Exercise Science and Sport Science, University of North Carolina, Chapel Hill.
Brian G
BG
Pietrosimone
College of Health Sciences, University of Kentucky, Lexington.
Phillip A
PA
Gribble
D000843:Ankle Joint / Q000503:physiopathology*; D002908:Chronic Disease; D003430:Cross-Sectional Studies; D004576:Electromyography; D005260:Female; D006801:Humans; D007593:Joint Instability / Q000503:physiopathology*; D035002:Lower Extremity / Q000502:physiology; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D055815:Young Adult
ankle injuries; feed-forward mechanism; hip; postural control; proprioception