VERTICAL JUMP HEIGHT IS PREDICTIVE OF HIP BONE MINERAL DENSITY IN MIDDLE-AGED WOMEN

Abstract

Osteoporosis is a disease characterized by low bone mineral density that affects approximately 44 million Americans. Women are prone to osteoporosis; hip fractures being one of the most common sites of fracture. PURPOSE The purpose of this study was to determine the relationship between vertical jump height (VJH) and hip bone mineral density (BMD) in 192 middle-aged women. METHODS The study design was cross-sectional and included women who were non-smokers. The vast majority of participants were Caucasian, educated, and married. Mean age for these women was 42.96 ± 3.01 years. VJH (cm) was measured using a Just Jump! platform (Probotics, Huntsville, AL). A demonstration of vertical jump technique, along with a maximum of two practice jumps, was performed. Each woman completed five measured jumps, resting as much as needed between each jump. The average of the five trials was computed. BMD were assessed by dual energy x-ray absorptiometry (Hologic QDR 4500, Waltham, MA). RESULTS The average of the five vertical jump trials was 27.75 ± 4.83 cm. Regression analysis showed no significant relationship between average VJH and hip BMD (F = 0.05, p = 0.82) or trochanter (troch) BMD (F = 0.35, p = 0.55). After controlling for weight and age, a significant relationship developed between VJH and total hip BMD (F = 6.30, p = 0.01) and troch BMD (F = 6.65, p = 0.01). VJH was segmented into quartiles. Comparison between the upper quartile and lower quartile showed 4.3% and 5.8% differences in BMD at the hip (p = 0.035) and troch (p = 0.018) respectively, with age and weight controlled. CONCLUSION Apparently, greater VJH, independent of age and body weight, is associated with higher levels of hip and troch BMD. Whereas, low VJH is associated with low levels of hip and troch BMD, independent of age and body weight. VJH may be a valuable screening method for detecting women who need further examination for low BMD at the hip.