Investigations into Changes in Bone Turnover with Acute, Weight-Bearing Exercise in Healthy, Young Men
QINETIQ LTD FARNBOROUGH (UNITED KINGDOM)
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Introductionrelevance to the Symposium Lower limb stress fracture injuries SFx account for a high number of working days lost during initial UK military training, cause considerable morbidity to recruits and contribute significantly to the high attrition from training. Rationale Recent evidence from the assessment of circulating biochemical markers suggests that changes in bone turnover, a process in which old bone is removed bone resorption and new bone formed in its place might be involved in SFx development. Methods and Results Blood-borne markers of bone resorption C-terminal cross-linking telopeptide of type 1 collagen - Beta-CTX and bone formation N-terminal propeptides of procollagen type 1 - P1NP and other bone-associated factors parathyroid hormone - PTH, calcium, phosphate and osteoprotegerin - OPG were measured before, during and up to four days after acute bouts of weight-bearing exercise. Investigations examined i the effect of training status TS on responses to exhaustive exercise ii the effect of recovery duration 23 h vs 3 h RD between two bouts of moderate exercise iii the effect of increasing exercise intensity EI and iv the effects of acute, pre-exercise feeding PF. Beta-CTX, but not P1NP, was increased for four days following exhaustive exercise, but this response was not affected by TS. In contrast, two bouts of exercise separated by either 23 h or 3 h had no effect on Beta-CTX or P1NP. Beta-CTX but not P1NP was higher in the first hour post-exercise with exercise at the highest exercise intensity. PF suppressed resting Beta-CTX concentrations, although it did not suppress the rise in Beta-CTX with subsequent exercise but, compared with fasting, resulted in a greater increase. OPG was increased with exercise in all four investigations but this increase was not affected by TS, RD, EI or PF. Transient increases in PTH were seen with exercise in all studies.
- Anatomy and Physiology