High-impact jumping mitigates the short-term effects of low energy availability on bone resorption but not formation in regularly menstruating females: A randomized control trial

Low energy availability (LEA) is prevalent in active individuals and negatively impacts bone turnover in young females. High-impact exercise can promote bone health in an energy efficient manner and may benefit bone during periods of LEA. Nineteen regularly menstruating females (aged 18–31 years) participated in two three-day conditions providing 15 (LEA) and 45kcalskg fat-free mass−1day−1 (BAL) of energy availability, each beginning 3±1days following the self-reported onset of menses. Participants either did (LEA+J, n=10) or did not (LEA, n=9) perform 20 high-impact jumps twice per day during LEA, with P1NP, β-CTx (cir?culating biomarkers of bone formation and resorption, respectively) and other markers of LEA measured pre and post in a resting and fasted state. Data are presented as estimated marginal mean±95% CI. P1NP was significantly reduced in LEA (71.8±6.1–60.4±6.2ngmL−1, p<0.001, d=2.36) and LEA+J(93.9±13.4–85.2±12.3ngmL−1, p<0.001, d=1.66), and these effects were not significantly different (time by condition interaction: p=0.269). β-CTx was significantly in?creased in LEA (0.39±0.09–0.46±0.10ngmL−1, p=0.002, d=1.11) but not in LEA+J (0.65±0.08–0.65±0.08ngmL−1, p>0.999, d=0.19), and these effects were significantly different (time by condition interaction: p=0.007). Morning basal bone formation rate isreduced following 3days LEA, induced via dietary restriction, with or without high-impact jumping in regularly menstruating young females. However, high-impact jumping can prevent an increase in morning basal bone resorption rate and may benefit long-term bone health in individuals repeatedly exposed to such bouts.