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Single-Leg Drop Jump Biomechanics After Ankle or Knee Joint Cooling in Healthy Young Adults.

CONTEXT
It is unclear if lower-extremity joint cooling alters biomechanics during a functional movement.


OBJECTIVE
To investigate the effects of unilateral lower-extremity cryotherapy on movement alterations during a single-leg drop jump.


DESIGN
A crossover design.


SETTING
Laboratory.


PATIENTS
Twenty healthy subjects (10 males and 10 females; 23 y, 169 cm, 66 kg).


INTERVENTION(S)
Subjects completed a single-leg drop jump before and after a 20-minute ankle or knee joint cooling on the right leg, or control (seated without cooling) on 3 separate days.


MAIN OUTCOME MEASURES
Time to peak knee flexion, vertical ground reaction force, lower-extremity joint angular velocity (sagittal plane only), and angle and moment (sagittal and frontal planes) in the involved leg over the entire ground contact (GC; from initial contact to jump-off) during the first landing. Time to peak knee flexion was compared using an analysis of variance; the rest of the outcome measures were analyzed using functional analyses of variance (P < .05).


RESULTS
Neither joint cooling condition changed the time to peak knee flexion (F2,95 = 0.73, P = .49). Ankle joint cooling reduced vertical ground reaction force (55 N at 4% of GC), knee joint angular velocity (44°/s during 5%-9% of GC), and knee varus moment (181 N·m during 18%-20% of GC). Knee joint cooling resulted in a reduction in knee joint angular velocity (24°/s during 37%-40% of GC) and hip adduction moment (151 N·m during 46%-48% of GC), and an increase in hip joint angular velocity (16°/s during 49%-53% of GC) and plantarflexion angle (1.5° during 11%-29% of GC).


CONCLUSION
Resuming activity immediately after lower-extremity joint cooling does not seem to predispose an individual to injury during landing because altered mechanics are neither overlapping with the injury time period nor of sufficient magnitude to lead to an injury.