The Impact of Lifestyle Factors on Stress Fractures in Female Army Recruits

Abstract

Estimates are that stress fractures during basic training (BT) occur in as many as 14% of US female military recruits. Injuries of this type lead to morbidity ranging from minor pain to serious lifetime disability. Since women are assuming an increasing role in the military, this high risk of stress fracture is of concern. The purpose of this prospective study was to determine factors that predict stress fracture during BT in US Army female recruits. The analysis was part of an investigation using quantitative ultrasound (QUS) to determine risk of stress fracture during BT. Prior to the start of BT, we obtained QUS measurements and asked each subject to complete a risk factor questionnaire. We completed assessments for 3758 recruits who then proceeded to 8 weeks of BT, during which time any diagnosed stress fractures were reported to us by Army clinicians. Stress fractures were confirmed with radiographs. The incidence of stress fracture was 8.5% per 8 weeks. Factors associated with stress fracture include: QUS, age, race, alcohol and tobacco use, weight-bearing exercise, lowest adult weight, corticosteroid use, and, in white women only, use of depo-medroxyprogesterone acetate (DMPA). Women who fractured were older than women who remained fracture-free, and black women were less likely to sustain a fracture than whites and other races. Compared with their non-stress-fracture counterparts, recruits who developed stress fractures were more likely to report current or past smoking, alcoholic drinking of > 10 drinks/week, corticosteroid use and lower adult weight. A history of regular exercise was protective against stress fracture, and a longer history of exercise further decreased the relative risk of fracture. Although current weight was not associated with stress fracture, lowest adult weight was inversely related to the risk of fracture. We conclude that prevention of stress fractures in female military recruits should include a thorough assessment of lifestyle factors such as exercise patterns, alcohol and tobacco habits, and corticosteroid and DMPA use. Assessment of risk factors may be helpful in pinpointing female recruits who should have further evaluation of their bone health or additional preparation, such as gradual increases in physical activity, prior to being exposed to the rigor of BT.

RANK/RANKL/OPG pathway: Genetic associations with stress fracture period prevalence in elite athletes

“…This can lead to bone loss and subsequent micro-damage that can result in localised bone weakening, prompting stress fracture development (2). Stress fracture period prevalence in elite athletes and military recruits ranges from 14 to 21% (3,4), and most commonly manifests in the lower limbs (5).…”

“…Susceptibility may also have genetic origins, supported by reports of monozygotic twins developing similar stress fracture injuries (8), multiple stress fractures occurring in the same individual (9), stress fractures occurring in some individuals but not in others undertaking identical training protocols (3,4) and a family history of stress fracture injury acting as a risk factor (10).…”

Stress fractures in elderly patients

“…In addition, Lappe et al analysed 3,758 female recruits and found that after eight weeks of basic training stress fractures were more likely to be reported by recruits with a current or past history of smoking or regular consumption of alcohol [5]. We also analysed lifestyle risk factors and found nicotine abuse in 46.7 % of male patients within the study group and thus significantly more often compared to female patients.…”

“…Stress fractures have been reported to be a common problem in young and active people such as athletes and military recruits [1][2][3][4][5]. Based on their aetiology, stress fractures can be subdivided into either fatigue-or insufficiency-related fractures.…”

“…The cause of stress fractures is often multifactorial [17,18] and various modifiable and non-modifiable factors have been proposed to play a role: white race [12], high bone turnover [1], vitamin D insufficiency [19], nicotine and alcohol abuse [5], steroid use [5], low bone density [20], low adult weight [5], anorexia [21], or bisphosphonate therapy [22,23]. Furthermore, female gender has been identified as an important risk factor and thus sex-specific effects appear to play a role in the pathogenesis of stress fractures [1].…”