Effect of short-term fatigue, induced by high-intensity exercise, on the profile of the ground reaction force during single-leg anterior drop-jumps.
Saya Watanabe, Junya Aizawa, Manabu Shimoda and 4 others
PMID 28174454WHAT IT FOUND
Fatigue from hard cycling shortened the time to peak landing force in male athletes.
Peak force and loading rate changes were not significant. This is a landing pattern linked to fatigue, not evidence of injury prevention.
Key findings
01The fatigue protocol reduced cycling mean power from 597 ± 100 W to 456 ± 62 W and peak velocity from 159 ± 16 rpm to 132 ± 19 rpm.
02Fatigue shortened the time from initial foot contact to peak vertical ground reaction force by 10.0% (p<0.05), from 44.0 ± 16.8 ms to 39.6 ± 15.8 ms.
03Peak vertical force decreased 3.6% and loading rate increased 9.4% with fatigue, but neither change reached statistical significance.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
Only 12 healthy male collegiate athletes were studied, so the results may not apply to women, younger athletes, less active people, or injured patients. The outcomes were force plate variables during a controlled drop-jump, not pain, function, or ACL injury. Three of twelve participants could not complete all six cycling bouts, so fatigue may not have been uniform. The authors did not measure joint angles, muscle activity or muscle force, so their proposed mechanism linking fatigue to ACL risk was not tested in this study.
The easy way to misread this
Do not conclude that fatigue causes ACL injury or that endurance training prevents it. The study measured only landing force timing in healthy male athletes, and the peak force and loading rate changes were not significant.