High-speed running training influences bone metabolism markers in collegiate male long-distance runners

BACKGROUND: Long-distance runners have a high incidence of stress fractures. However, the content of training which has a negative effect on bone has not been clarified in long-distance runners. The purpose of this study is to clarify the effect of training quantity (running distance) and training quality (running speed) on bone metabolism markers in long- distance runners who develop multiple stress fractures.METHODS: BAP as bone formation marker, urine-NTX as bone resorption markers were measured. The first measurement was taken after an Off period of one week. The second was taken after a one-week training period (long-distance period: LD period) with a high-quantity training aimed for long training runs. The third was taken after participating in a 10,000-m race (high-speed period: HS period) which was aimed for speed strengthening. The total distance running per week was measured for each period.RESULTS: A weekly running distance was Off period 75.0 km, LD period 242.3 km and period 112.5 km. BAP was lower (P<0.05) in HS period (17.4±6.1 µg/L) than in LD period (19.5±5.9 µg/L). Urine-NTX was higher in HS period (75.9±34.1 nmol BCE/mmol CRE) compared to LD period (65.0±30.7 nmol BCE/mmol CRE; P<0.05).CONCLUSIONS: In male long-distance runners, bone metabolism markers did not fluctuate with high training quantity and low training quality (low impact on bone). Conversely, we observed that bone turnover leaned toward bone resorption with low training quantity and high training quality (high impact on bone).