Association Between Serum 25(OH)D Concentrations and Bone Stress Fractures in Finnish Young Men

Abstract

A correlation has also been found between low femoral BMD and stress fractures. We measured serum 25(OH)D concentration in a population sample of military recruits to determine if vitamin D is a predisposing factor for fatigue bone stress fracture. Materials and Methods: We prospectively followed 800 randomly selected, healthy Finnish military recruits with a mean age of 19 years for developing stress fractures in homogenous circumstances. Blood for serum 25(OH)D concentration was drawn at entry into military service, and the weight, height, body mass index (BMI), muscle strength, and 12-minute running were measured for all subjects. Serum 25(OH)D concentrations were measured with enzyme immunoassay. At end of the 90-day follow-up, 756 subjects completed the study. Subjects without fracture constituted controls. Results: Twenty-two recruits with stress fracture were identified (2.9%), the incidence being 11.6 (95% CI: 6.8-16.5) per 100 person-years. In the final multivariate analysis, the significant risk factor for stress fracture in conscripts was a below median serum 25(OH)D level (75.8 nM), OR being 3.6 (95% CI: 1.2-11.1). No significant associations between BMI (p ‫ס‬ 0.255), age (p ‫ס‬ 0.216), or smoking (p ‫ס‬ 0.851) and bone stress fracture were found in this study population. Conclusions: A lower level of serum 25(OH)D concentration may be a generally predisposing element for bone stress fractures. Considering the obvious need of additional vitamin D in prevention of stress fractures, the effects of vitamin D fortification of foods and supplementation will be subjects of interest for future research.

Analysis of stress fractures in athletes based on our clinical experience

“…Many clinical risk factors of stress fractures have been identified. In particular, polymorphism of vitamin D receptor (Fokl and Bsml), vitamin D insufficiency, low bone mass, low body mass index, poor physical fitness/condition, gender (female), low bone turnover, and amenorrhea were suggested to be clinical risk factors of stress fractures [4][5][6][7][8][9][10][11] . One athlete in our study who sustained a stress fracture had vitamin D insufficiency.…”

“…Epidemiological studies have identified the clinical risk factors of stress fractures in athletes and military recruits. The etiology of stress fractures is multifactorial and many clinical risk factors have been identified; polymorphism of vitamin D receptor (Fokl and Bsml) [4] , low serum levels of 25(OH)D [5] , high serum parathyroid hormone level [6] , low stiffness index (heel quantitative ultrasound parameter) [4,7] , low bone mineral content and density (BMC and BMD, respectively) of the hip [6] , tall stature [6,8] , leanness [8] , poor physical fitness/condition [6,9,10] , sense of burnout [8] , iron deficiency [8] , higher age [9] , gender (female) [9,11] , low bone turnover [7] , smoking [10] , and amenorrhea [10] . However, no consensus has been reached.…”

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

“…55 In a prospective study, in Finnish army recruits, high serum PTH levels were identified as a risk factor for stress fracture development. 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.…”

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.…”