The purpose of this study was to examine gender differences in peak vertical Ground Reaction Force (VGRF) and Rate of Loading (ROL) during stop-jump task. Forty four healthy students 22 males (weight 75.89 ± 3.22 kg, height 177.84 ± 4.52 cm, age 24 ± 3 years) and 22 females (weight 64.17 ± 2.85 kg, height 164.20 ± 5.58 cm, age 22 ± 2 years,) from kinesiology department volunteered in this study. Subjects performed stop-jump task on the force plate. Peak VGRF and ROL of subjects calculated using GRF data. To evaluate differences in peak VGRF and ROL between two groups Multivariate analysis of Variance (MANOVA) at the P level of 0.05 used. Significant differences seen between two groups for ROL (F1, 41=5.627, Wilks’ Lambda = 0.372, P≤0.05). ROL in females was 15.85 percent greater than males (479.10 ±113.30 for females and 403.20 ± 98.50 for males), but there was not any significant differences between two groups for peak VGRF (F1, 42 = 2.818, P >0.05). Based on our results,it seems thatincrease in female’s ROL during impact of landing can increase her knee loading secondary, and consequently create higher incidence of knee injuries, especially ACL, among females compare to males. The probable reason for increase of ROL in females can be attributed to differences in their landing pattern or their neuromuscular controls.
