Effects of High-Impact Exercise on Bone Marker Concentrations During Controlled Low Energy Availability in...

Exposure to low energy availability (LEA) can stimulate metabolic adaptations that have been shown to disrupt bone remodeling as suggested by suppressed markers of bone formation and/or increased markers of bone resorption. Previous studies suggest that brief, high-impact exercise during short-term energy restriction may stimulate an osteogenic response and mitigate the negative effect of LEA on bone health. This randomized, crossover study of twelve recreational female runners (age: 26.4 ± 3.9 years, VO_2max: 45.3 ± 7.2 mL/kg/min) assessed the short-term effects of jumping exercises on markers of bone formation and resorption after five days of experimentally-controlled LEA (15 kcal/kgFFM/d). Participants completed two LEA conditions that involved daily treadmill running with either no additional exercise (RUN) or an additional 50 jump exercises per day (RUN + J). Fasted bone markers and hormone concentrations were measured on the mornings immediately before and after each intervention period. Bone resorption marker β-CTX was increased over time in both LEA conditions (main effect of time: P = 0.005; preRUN: 0.32 ± 0.21, postRUN: 0.36 ± 0.15 ng/mL; preRUN + J: 0.38 ± 0.21, postRUN + J: 0.42 ± 0.19 ng/mL) with no interaction effect (P = 0.716). Bone formation biomarkers, PINP and sclerostin, did not change over time (P = 0.517, P = 0.091) or between conditions (P = 0.187, P = 0.666). In conclusion, performing 50 jumping exercises during short-term LEA did not have an effect on markers of bone resorption or formation during short-term LEA induced by running exercise and dietary energy restriction.