Vertical Jump Test as a Health-Promotion Screening Tool for Predicting Bone Strength in Young Adults

Abstract

There are bone mineral density (BMD) testing recommendations for women ≥65 years and men ≥70 years to diagnose osteoporosis, but no such recommendations exist for screening purposes in the healthy adult population. A potential screening tool for bone strength is a peak vertical jump test. Vertical jump height can be used as a proxy for muscle power, an influential factor in determining bone mass and geometry (i.e., bone strength). PURPOSE: This study examined the relationship between muscle power and bone strength, and the capacity of a peak vertical jump test to identify young adults with below-average areal BMD (aBMD). METHODS: In total, 303 young adults (18-22 years, 136 males, 167 females) participated in this study. Total hip and femoral neck (FN) aBMD were assessed by dual x-ray absorptiometry (DXA) and DXA images were used to calculate FN section modulus values. Indices of bone strength were assessed at the tibia with peripheral quantitative computed tomography. Cortical bone area and density-weighted polar section modulus strength-strain index were assessed at 38% midshaft site and bone strength index was assessed at 4% midshaft site. Muscle power was predicted using vertical jump and the Sayers equation. Pearson bivariate and partial correlations examined associations among bone strength outcomes and muscle power. Logistic regression examined the probability of below-average bone strength based on muscle power. Receiver Operating Characteristic (ROC) curve analysis examined the sensitivity-specificity tradeoff and the accuracy of a peak vertical jump test as an aBMD assessment tool. RESULTS: The odds ratio of below-average height-adjusted FN aBMD decreased 5.4% for females and 3.6% for males per 50 Watts of power. ROC analysis showed the best cut point to identify individuals with below-average aBMD was 5,038 Watts in males (sensitivity = 73.7%; specificity = 62.4%; AUC = 0.709, 95%CI = 0.572-0.847) and 3,261 Watts in females (sensitivity = 71.4%; specificity = 58.9%; AUC = 0.708, 95%CI = 0.586-0.829). These values correspond to vertical jump heights of 54.4 cm and 36.2 cm for males and females. CONCLUSION: We found acceptable sensitivity and specificity and moderate discriminate ability for muscle power, assessed with a peak vertical jump test, to identify young adults with below-average aBMD.