Purpose: This study aimed 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: Ten men (age = 28 ± 5 yr, height = 1.74 ± 0.05 m, body mass [BM] = 69.7 ± 6.3 kg) performed treadmill running at 75% V˙O2max, until exhaustion, on three occasions. Blood was collected before and immediately, 1, 2, 3, 4, and 24 h postexercise, for measurement of β-CTX, P1NP, parathyroid hormone, PO4, ACa, and Ca. This was a randomized, counterbalanced, placebo-controlled, and single-blinded crossover study. The three trials were (i) placebo (PLA), where the PLA solution was ingested immediately and 2 h postexercise; (ii) immediate feeding (IF), where CHO + PRO (1.5 g·kg BM dextrose and 0.5 g·kg BM whey) was ingested immediately postexercise and PLA 2 h postexercise; and (iii) delayed feeding (DF), where PLA was ingested immediately postexercise and CHO + PRO solution 2 h postexercise. Data were analyzed using repeated-measures ANOVA and Tukey's HSD post hoc test.
Results: At 1 and 2 h postexercise, β-CTX concentrations were lower in the IF trial compared with the DF and PLA trials (P ≤ 0.001). At 3 h postexercise, β-CTX concentrations were higher in the PLA trial compared with the IF (P ≤ 0.001) and DF trials (P = 0.026). At 4 h postexercise, β-CTX concentrations were lower in the DF trial compared with the IF (P = 0.003) and PLA trials (P ≤ 0.001). At 4 h postexercise, P1NP was higher in the IF trial compared with the DF (P = 0.026) and PLA trials (P = 0.001). At 3 h postexercise, parathyroid hormone was higher in the IF trial compared with the DF trial (P ≤ 0.001).
Conclusions: After 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.