Jump landings are routinely used to study gender differences in landing. Standardizing the jump height to a fixed vertical distance may bias results as women are forced to land from heights that are a greater percentage of their own maximum vertical jump (MVJ).

PURPOSE: To compare lower extremity mechanics between genders from a fixed height and from a self initiated jump.

METHODS: Nine male (21.50±1.20 years, 173.25±2.82cm, 75.58±7.92kg, 60.97±5.81cm MVJ) and 8 female (20.56±1.24 years, 161.11±6.01cm, 57.58±11.65kg, 33.13±9.76cm MVJ) subjects participated in this study. Subjects were given standard footwear. Maximum vertical jump heights were obtained. Subjects performed 6 successful trials of a drop landing (DL) from a 61cm height and a self initiated vertical jump landing (VJ) at their 80% MVJ height in random order. A 6-camera, EVa 3-D motion capture system (Motion Analysis, Santa Rosa, CA) captured (120 Hz) and analyzed (EVa version 5.11 and KinTrak 6.0 software) dominant lower extremity joint kinematics based on an 11 marker, 3 segment (thigh, shank, foot) model. Joint centers for the hip, knee and ankle were created according to Euler angle calculations. A synchronized force plate (AMTI, Watertown, MA) recorded time of initial contact and maximal vertical force. Dependent variables included: knee flexion angles at initial contact (KFIC), at maximal vertical ground reaction force, (KFMZ) and maximum knee flexion angle (MaxKF). Data were exported into spreadsheet and means for all trials in both conditions were created and imported to SPSS 13.0. Two 1-way ANOVAs tested for differences (P = 0.05) between groups in each condition.

RESULTS: No significant differences were found between males and females for KFIC or KFMZ in either the VJ or DL. No significant difference was found in MaxKF between males (75.55± 8.46) and females (67.52± 6.31) in the DL. However, males had greater MaxKF angles (83.38± 18.90) than females in the VJ (66.22±15.01) (P= .001).

CONCLUSIONS: Contrary to other published reports, our results showed no difference in knee flexion angles between genders in a DL task. Males exhibited greater absolute knee flexion in the VJ, which is not surprising given their MVJ heights. Future research investigating lower extremity motion during landing should incorporate appropriately comparable tasks.

Erik E. Swartz¹, Adam Hernandez², Dain LaRoche¹, Laura C. Decoster³. ¹University of New Hampshire, Durham, NH. ² Indiana State University, Terre Haute, IN. ³New Hampshire Musculoskeletal Institute, Manchester, NH