Author(s): GARDY, S., FERREIRA, S.V., LINARDATOS, J.R., PELLAR, S.T., JOSSE, A.R., CHURCHWARD-VENNE, T.A., CORREA, J.A., GIBBS, J.C., Institution: MCGILL UNIVERSITY, Country: CANADA, Abstract-ID: 2670

INTRODUCTION:
Endurance runners are at increased risk for bone stress injury, partly due to repeated prolonged running that can elevate bone resorption during and after exercise. Post-exercise nutrition may attenuate this ostensible catabolic response, and dietary protein is a key nutrient involved in bone remodeling. While protein, particularly when co-ingested with carbohydrate, may transiently blunt exercise-induced increases in biomarkers of bone resorption, the acute effects of post-exercise dietary protein ingestion versus a non-caloric control in female and male endurance runners remain unknown.
METHODS:
Using a randomized, double-blinded, repeated measures, crossover design, young female and male endurance runners (n=14) completed two matched trials of a time-to-exhaustion run at a fixed intensity (70% maximum oxygen consumption) and ingested either a (1) whey protein-rich beverage (0.5 g·kg−1 BM) or (2) water beverage immediately post-exercise. Blood samples were taken at baseline, 0, 1, 2, 3, 4 and 24-hours post-exercise. Beta C-telopeptide (β-CTX), N-terminal propeptide of type-1 collagen (PINP), sclerostin (SOST), insulin-like growth factor-1 (IGF-1), parathyroid hormone (PTH), leptin, and osteocalcin were measured by immunosorbent assays. Changes in marker concentration after beverage intake relative to rest were assessed by a linear mixed effects model and sex, sequence, period, and baseline difference were included as covariates. Post hoc pairwise time-point comparisons used model-based estimated marginal means with adjusted p-values.
RESULTS:
There was no treatment by time effect for any measured biomarker. Adjusted serum β-CTX concentrations were lower at 24 h vs. 0h (immediately post-exercise) (ratio: 1.13, 95% CI: (1.02, 1.26); p = 0.01). There were significant effects for time for serum P1NP (p < 0.001), SOST (p < 0.0001), PTH (p < 0.001), leptin (p < 0.01), and osteocalcin (p < 0.001). A main effect of treatment was observed for IGF-1 and osteocalcin (both p < 0.01), indicating higher IGF-1 concentrations with protein and higher osteocalcin concentrations with control when averaged across the 24 h recovery period.
CONCLUSION:
Acute whey protein ingestion compared to a non-caloric control had no effect on serum β-CTX and other markers related to the bone metabolic response during the 24 h recovery period following exhaustive running exercise in endurance runners.