Evaluating the Risk of a Fifth Metatarsal Stress Fracture by Measuring the Serum 25-Hydroxyvitamin D Levels.

BACKGROUND: The fifth metatarsal bone is a common site of stress fractures in soccer athletes. Although several endocrine risk factors for stress fractures have been proposed, the endocrine risks for fifth metatarsal (5-MT) stress fractures have not been evaluated. METHODS: To evaluate the endocrine risks of fifth metatarsal stress fractures, we conducted a cumulative case-control study. The present study included 37 athletes, of which 18 had a history of a zone 2 or zone 3 fifth metatarsal stress fracture and 19 controls. We analyzed serum 25-hydroxyvitamin D (25-OHD), serum parathyroid hormone (PTH), as well as biochemical markers of bone turnover by univariate or multivariate analyses. RESULTS: Logistic regression analyses adjusted for multiple confounders revealed that insufficient serum 25-OHD levels less than 30 ng/mL (odds ratio [OR], 23.3), higher serum PTH levels (OR, 1.01), or higher serum bone-specific isoform of alkaline phosphatase levels (OR, 1.10) rather than serum tartrate-resistant acid phosphatase 5b were associated with statistically significantly increased odds of 5-MT stress fractures. A postestimation calculation demonstrated that 25-OHD levels of 10 and 20 ng/mL were associated with 5.1 and 2.9 times greater odds for 5-MT stress fractures, respectively. CONCLUSION: 25-OHD insufficiency was associated with an increased incidence of 5-MT stress fractures. This insight may be useful for intervening to prevent 5-MT stress fractures. LEVEL OF EVIDENCE: Level III, case-control study.

Post-training consumption of wheat gluten hydrolysate suppresses the delayed onset of muscle injury in soccer players.

Wheat gluten hydrolysate (WGH) is reported to suppress the muscle injuries associated with exercise in long distance running and weight training. In the present study, we investigated the effects of WGH consumption on suppression of muscle injury after soccer training in a double-blind crossover study. Immediately after a mini soccer game, six soccer players consumed 18.0 g of WGH, and muscle injury was investigated using serum creatine kinase (CK) as an indicator. The results showed a significant increase in serum CK from immediately after exercise to 12 h after exercise stress (p<0.05) in the placebo group, while serum CK decreased during this same time period in the WGH group, and the difference between the two groups was significant. This suggests that WGH consumption suppresses delayed-onset muscle injury after exercise in soccer.