Comparing Water Polo Players’ Dryland And In-water Vertical Jump To Bone Strength And Power

INTRODUCTION: Athletes generally have stronger bones due to high-impact loading, but water sport athletes show mixed evidence. Lower bone strength may not affect daily activities but could increase injury risk under extreme conditions. Monitoring bone health in water athletes may aid injury prevention. Power has emerged as a potential indicator of bone health, but it is unclear if dryland peak vertical jump power predicts bone strength in water athletes. Water polo movements differ from a dryland vertical jump. PURPOSE: This study examines whether dryland vertical jump power better predicts bone strength than in-water jump power in female water polo players. METHODS: Participants: 19 collegiate and recreational females (swimmers n = 9, water polo n = 7, active females n = 3; age 20 ± 1.4 yrs; height 166.8 ± 6.4 cm; body mass 68.7 ± 12.3 kg). Outcome Measures: Height, mass, and demographic survey data were collected. Vertical jumps were performed on dryland and in-water using a Vertec. Rectus femoris activation was monitored via electromyography (EMG). Dryland jump reach height followed standard protocol. In-water jump reach height was measured from ASIS to fingertip. Peripheral Quantitative Computed Tomography (pQCT) measured tibial cortical bone strength, including MoI, Ct.Ar, cBMD, and SSIp. Power was calculated for dryland using Sayers Countermovement Vertical Jump CMVJ equation and for in-water using Power = force × velocity, where force = buoyancy and velocity = jump height divided by muscle activation time from EMG. Linear regressions analyzed peak jump power vs. bone strength variables. RESULTS: Mean dryland jump height: 42.6 ± 5.7 cm, peak power: 3659.8 ± 639.9 W. Mean in-water jump height: 50.1 ± 13.9 cm, power: 150.7 ± 10.8 W. No significant regressions, but in-water peak power had higher coefficients of determination for Ct.Ar, MoI, and SSIp (R2 = 0.2352; 0.2119; 0.3143) vs. dryland power (R2 = 0.0033; 0.0222; 0.0334). EMG data limited jump power calculations to 10 participants. No correlation existed between relative dryland and in-water jump heights (r = 0.004), indicating different movement patterns. CONCLUSIONS: Neither dryland nor in-water power predicted bone strength in water sport athletes. Further research is needed to identify better screening measures for bone strength in this population. Supported by: OSCAR Program, Kinesiology Research Group, CSUEB