Changes Of Bone Metabolism Markers In Japanese Male Long Distance Runners During In-season

Abstract

Stress fracture is one of the most common overuse injuries in runners and there are many risk factors that predispose to this injury. Previous studies have focused on bone metabolism and the correlation between stress fractures and bone metabolism has been reported. However, most studies are on female athletes, and little is known on male athletes. Moreover, long-term bone metabolic process in athletes is unknown. PURPOSE: To investigate changes bone metabolism markers in male long distance runners during in-season METHODS: Twenty-five male long distance runners participated in this study, and total of 11 athletes were qualified for analysis (24 ± 4.3 yrs, 170.4 ± 5.0 cm, 55.9 ± 3.7 kg) after excluding those who were injured and/or were not able to run more than 200 km per month. Blood samples were collected from 9 am to 11 am during pre-season (PRs), post-track season (PTs), and road-race season(RRs). Athletes were instructed to refrain from training prior to blood collection. To assess bone metabolism bone-specific alkaline phosphatase(BAP) and tartrate-resistant acid phosphatase-5b(TRACP-5b) were measured. In addition, athletes reported their monthly training volume of one month prior the first measurement. Changes of bone metabolic markers were assessed by one-way ANOVA with repeated measures and correlations between training volume and both markers were made using Spearman’s rank correlation coefficient. RESULTS: BAP in PTs (14.98 ± 3.11 vs. 16.62 ± 3.76 p = 0.004) and RRs (14.85 ± 3.68 vs. 16.62 ± 3.76 p = 0.004) were significantly lower than that of PRs. There were no statistically significant changes in TRACP-5b. Moreover, there were not any correlations between monthly training volume and both bone metabolism markers. CONCLUSIONS: We found that BAP lower than PRs from the latter half of track season to the road race season.