The influence of whole-body vibration on heart rate, stride length, and bone mineral content in the mature exercising horse

Abstract

Research in humans suggests whole-body vibration (WBV) aids in maintaining bone mineral content (BMC) yet results in the horse are less favourable. Anecdotally, WBV is reported to reduce pain and improve performance. This study was designed to test the effect of WBV on exercising horses, hypothesising that WBV would lower heart rate (HR) during treatment, increase BMC, modify markers of bone metabolism, and increase stride length. Eleven horses were randomly assigned into control (CON, n=5) or WBV (VIB, n=6) groups for a 28-day treatment period. Both groups exercised for 1 h, 6 d/wk on a mechanical exerciser. VIB horses received 50 Hz WBV for 45 min, 5 days/wk. Third metacarpal radiographs were taken at 0 and 28 days, and BMC determined via radiographic bone aluminium equivalence (RBAE). Blood samples taken at day 0 and 28 were analysed for serum pyridinoline cross-links (PYD) and osteocalcin (OC). Heart rate was analysed on day 23 for 4 horses per group. Stride length was determined while trotting in hand on day 0 and 28. No influence of WBV on RBAE of any bone cortices, PYD or OC was observed (P>0.10); stride length was also unaffected (P=0.88). A period effect was observed for a decrease in RBAE of the lateral cortex (P=0.01), and a trend towards a decrease was noted in total density (P=0.05), likely an effect of stalling. Compared to baseline, ΔHR declined during treatment (P=0.06) in VIB (-4.8±2.8 bpm) compared to control CON (3.0±2.8 bpm). The results suggest, in normal exercising horses, WBV does not increase BMC, influence markers of bone metabolism, or increase stride length.