Fatigue influences lower extremity angular velocities during a single-leg drop vertical jump.
Akihiro Tamura, Kiyokazu Akasaka, Takahiro Otsudo and 3 others
PMID 28356640WHAT IT FOUND
After a short cycling fatigue task, young women landed a single-leg drop jump with faster bending at the hip and knee than controls.
Joint positions did not change, and the study did not measure injuries or patients.
Key findings
01Fatigue increased peak hip and knee flexion angular velocity from pre to post compared with control, while peak joint angles and ankle angular velocity did not differ.
02At 40 milliseconds after initial ground contact, fatigue increased hip flexion angular velocity relative to control, but knee and ankle angular velocities were unchanged.
03At initial ground contact and at peak vertical ground reaction force, fatigue did not change lower extremity joint angles or angular velocities.
STILL TO COME
How it was doneWhat they foundWhat it means for PTs
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What it does not show
The participants were 34 females with no reported hip, knee, or ankle surgery history, so the findings may not apply to males, older adults, injured patients, or people with joint conditions. The outcomes were laboratory jump-landing kinematics, not pain, function, falls, or injury, so this study does not show that fatigue causes injury or that these changes matter clinically. The study compared many hip, knee, and ankle kinematic variables, and the paper does not name one primary endpoint. The fatigue protocol was cycling for 5 minutes, not a real game or sport exposure, so transfer to late-game fatigue is limited. All participants landed on their dominant leg only, so the results do not show what happens on the non-dominant leg.
The easy way to misread this
Do not conclude that fatigue causes ACL injury or that these angular velocity changes predict injury in patients. The study measured only lab jump-landing kinematics in 34 females with no reported hip, knee, or ankle surgery history, did not test injury outcomes, and did not show that fatigue changed knee kinematics at the 40 millisecond window after initial ground contact.