Calcium and Vitamin D Supplementation Decreases Incidence of Stress Fractures in Female Navy Recruits

Abstract

ABSTRACT:Introduction: Stress fractures (SFx) are one of the most common and debilitating overuse injuries seen in military recruits, and they are also problematic for nonmilitary athletic populations. The goal of this randomized double-blind, placebo-controlled study was to determine whether a calcium and vitamin D intervention could reduce the incidence of SFx in female recruits during basic training. Materials and Methods: We recruited 5201 female Navy recruit volunteers and randomized them to 2000 mg calcium and 800 IU vitamin D/d or placebo. SFx were ascertained when recruits reported to the Great Lakes clinic with symptoms. All SFx were confirmed with radiography or technetium scan according to the usual Navy protocol. Results: A total of 309 subjects were diagnosed with a SFx resulting in an incidence of 5.9% per 8 wk. Using intention-to-treat analysis by including all enrolled subjects, we found that the calcium and vitamin D group had a 20% lower incidence of SFx than the control group (5.3% versus 6.6%, respectively, p ‫ס‬ 0.0026 for Fisher's exact test). The per protocol analysis, including only the 3700 recruits who completed the study, found a 21% lower incidence of fractures in the supplemented versus the control group (6.8% versus 8.6%, respectively, p ‫ס‬ 0.02 for Fisher's exact test). Conclusions: Generalizing the findings to the population of 14,416 women who entered basic training at the Great Lakes during the 24 mo of recruitment, calcium and vitamin D supplementation for the entire cohort would have prevented ∼187 persons from fracturing. Such a decrease in SFx would be associated with a significant decrease in morbidity and financial costs.

Low 25(OH) vitamin D concentrations in international UK track and field athletes

“…56 In two studies lower 25(OH)D levels have been found to be associated with a significantly increased risk of stress fracture in young Finnish men 57 and with high-grade stress fractures, in a large army cohort. 58 One randomised controlled trial of more than 5 000 army recruits reports a reduction in stress fractures after daily supplementation of 2 g calcium and 800 IU vitamin D. 59 In addition to the classic role in bone metabolism, vitamin D deficiency may directly impact on athletic performance through other physiological mechanisms including muscle function, 38,[60][61][62] immunity and the potential mediation of exercise-induced inflammation. 63,64 The vitamin D receptor and intracellular vitamin D regulation have also been identified in heart muscle, liver, lung and adrenal systems, all of which are determinants of athletic performance.…”

Effect of fasting versus feeding on the bone metabolic response to running

“…This acute response may be of significance to athletic populations as the net effects of changes in bone resorption and formation have been implicated in both stress fractures [20] and changes in bone mineral density (BMD) [21]. Additionally, the acute response of bone markers to exercise has been reported with both running [19] and cycling [15], and reduced spinal BMD (running and cycling) and an increased incidence of stress fractures (running) have been observed in some groups who regularly perform both types of activity [22][23][24][25][26].…”

Vitamin D deficiency is endemic in Middle Eastern sportsmen

“…For example, in a recent study of ninety-nine postmenarchal adolescent girls in England, Ward et al (32) found a positive relationship between serum 25(OH)D level and jump height, jump velocity and power. In addition to any immediate performance deficits for athletes, 25(OH)D deficiency may have both immediate effects on health such as stress fractures, as well as substantial long-term health impacts (4,34,35) . Subsequently the identification and correction of any deficiency is of paramount importance.…”