Ground Reaction Forces Among Gymnasts and Recreational Athletes in Drop Landings.

OBJECTIVE: To compare vertical ground reaction forces among gymnasts and recreational athletes during drop landings from 30-, 60-, and 90-cm heights. DESIGN AND SETTING: Two subject groups, intercollegiate gymnasts and college-aged recreational athletes, participated in this study. Subjects completed 10 landing trials onto a force platform at each height. SUBJECTS: Ten female competitive gymnasts (height = 1.57 +/- 0.02 m, mass = 55.4 +/- 7.3 kg) and 10 female recreational athletes (height = 1.63 +/- 0.06 m, mass = 59.6 +/- 4.9 kg) volunteered for this study. MEASUREMENTS: Measurements of first peak-force magnitude (F1), time to F1 (T1), impulse to F1, second peak-force magnitude (F2), time to F2 (T2), and impulse to F2 were compiled to describe the ground reaction force profile for each trial at 30-, 60-, and 90-cm platform heights. A 2 x 3 (group x height) mixed-factors analysis of variance was calculated for each of the 6 variables. RESULTS: The group-by-height interaction was significant for F1, F2, and impulse to F2. Tukey post hoc analyses revealed significantly higher values for the gymnasts than for the recreational athletes at 60- and 90-cm heights for F1 and F2 magnitudes. Differences between groups for T1, T2, impulse to F1, and impulse to F2 were not statistically significant at any height. CONCLUSIONS: Drop landings performed by female gymnasts at 60- and 90-cm heights exhibited higher vertical ground reaction forces than drop landings performed by female recreational athletes. High ground reaction forces experienced by gymnasts during landings may contribute to the incidence of lower extremity injuries.