The effects of cryotherapy on ground-reaction forces produced during a functional task

Objective: To determine whether a standard 20-min ice-bath (10 degrees C) i mmersion of the leg alters vertical ground-reaction-force components during a 1-legged vertical jump. Design: Al x 5 factorial repeated-measures model was used. Setting: The Applied Biomechanics Laboratory at The University of Mississip pi. Participants: Fifteen healthy and physically active subjects (age = 22.3 +/ - 2.1 years, height = 177.3 +/- 12.2 cm, mass = 76.3 +/- 19.1 kg) participa ted. Intervention: Subjects performed 25 one-legged vertical jumps with their pr eferred extremity before (5 jumps) and after (20 jumps) a 20-min cold whirl pool to the leg. The 25 jumps were reduced into 5 sets of average trials. Main Outcome Measures: Normalized peak and average vertical ground-reaction forces, as well as vertical impulse obtained using an instrumented force p latform. Results: Immediately after cryotherapy (sets 2 and 3), vertical im pulse decreased (P = .01); peak vertical ground-reaction force increased (s et 2) but then decreased toward baseline measures (P = .02). Average vertic al ground-reaction force remained unchanged (P > .05). Conclusions: The authors advocate waiting approximately 15 min before engag ing in activities that require the production of weight-bearing explosive s trength or power.