The bone biomarker response to an acute bout of exercise: a systematic review with meta-analysis.

Circulating biomarkers are often used to investigate the bone response to an acute bout of exercise, but heterogeneity in factors such as study design, quality, selected biomarkers and exercise and participant characteristics render it difficult to synthesize and evaluate available evidence. To quantify the effects of an acute exercise bout on bone biomarkers, along with the influence of potential moderators such as participant, exercise and design characteristics, using a systematic review and meta-analytic approach. The protocol was designed in accordance with PRISMA-P guidelines and prospectively published. Seven databases were systematically searched in accordance with pre-defined eligibility criteria. Bayesian three-level hierarchical meta-analysis models were used to explore main effects of acute exercise on bone biomarkers, as well as potential moderating factors. Modelled effect sizes were interpreted according to three metrics namely: A) Evidence of an effect (defined by whether, or how much of, the CrI included zero); B) The size of that effect (threshold values of 0.01, 0.2, 0.5 and 0.8 were used to describe effect sizes as very small, small, medium and large, respectively); and C) The level of certainty in the estimated effect (defined using the GRADE framework). Pooling of outcomes across all designs and categories indicated that an acute bout of exercise increased bone resorption (ES0.5=0.10 [95%CrI: 0.00 to 0.20] and formation (ES0.5=0.05 [95%CrI: 0.01 to 0.08] markers, but the effects were very small and highly variable Moderator analyses revealed the source of some of this variability and indicated that exercise type and impact loading influenced the bone resorptive response. A moderate increase in CTX-1 was observed in response to cycling (ES0.5=0.65 [95%CrI: 0.20 to 0.99]), with greater durations and more work leading to larger CTX-1 increases. CTX-1 response peaked within 15 minutes and 2 hours after the exercise bout. Other exercise types did not influence CTX-1. Changes to all bone ...