The effect of postexercise carbohydrate and protein ingestion on bone metabolism

Purpose: To investigate the effect of feeding carbohydrate and protein (CHO+PRO), immediately or 2 h after an exhaustive run, on the bone turnover response in endurance runners. Methods: 10 men (age 28+/-5 y, height 1.74+/-0.05 m, body mass 69.7+/-6.3 kg) performed treadmill running at 75%VO2max, until exhaustion, on three occasions. Blood was collected before and immediately, 1, 2, 3, 4 and 24 h post-exercise, for measurement of [beta]-CTX, P1NP, PTH, PO4, ACa and Ca2+. This was a randomised, counterbalanced, placebo-controlled, single-blinded, cross-over study. The three trials were; i) placebo (PLA), PLA solution was ingested immediately and 2 h post-exercise, ii) immediate feeding (IF), CHO+PRO (1.5 g.kgBM-1 dextrose and 0.5 g.kgBM-1 whey) were ingested immediately post-exercise and PLA 2 h post-exercise, and iii) delayed feeding (DF), PLA was ingested immediately post-exercise and CHO+PRO solution 2 h post-exercise. Data were analysed using repeated measures ANOVA and post-hoc Tukey's HSD. Results: At 1 and 2 h post-exercise, [beta]-CTX concentrations were lower in the IF trial than the DF and PLA trials (P<=0.001). At 3 h post-exercise, [beta]-CTX concentrations were higher in the PLA trial than the IF (P<=0.001) and DF trials (P=0.026). At 4 h post-exercise, [beta]-CTX concentrations were lower in the DF trial than the IF (P=0.003) and PLA trials (P<=0.001). At 4 h post-exercise, P1NP was higher in the IF trial than in DF (P=0.026) and PLA trials (P=0.001). At 3 h post-exercise, PTH was higher in the IF trial than the DF trial (P<=0.001). Conclusions: Following exhaustive running, immediate ingestion of CHO+PRO may be beneficial, as it decreases bone resorption marker concentrations and increases bone formation marker concentrations; creating a more positive bone turnover balance.