Stress Fractures

I cannot think about stress fractures of any type without considering Finestone & Milgrom (2008), who investigated various interventions over 25 years and the impact they had on the incidence of lower limb stress fractures in military recruits. Ultimately, concluding that the most effective way to reduce the incidence of lower limb stress fractures in military recruits was to ensure a minimum of 6 hours of sleep a night and reduce cumulative marching and running volume.

Finestone & Milgrom (2008) also observed that prior activity history could be protective: recruits who had participated in basketball approximately three times per week for two or more years had a reduced risk of stress fracture, whereas those with a history of long-distance running did not. It was inferred that higher impact stress from basketball-induced cyclical loading may lead to greater protective bone adaptation than repetitive loading from long-distance running. Suggesting that any activity that primarily emphasises uniplanar motion with repetitive loading cycles that lack variety in the plane of motion or in intensity, combined with inadequate de-loading to enable bone adaptation, could contribute to the development of stress fractures.

Bennell et al. (1996) observed that female athletes who developed stress fractures had significantly less total-body bone mineral content, lower lumbar spine and foot bone density, less lean mass in the lower limb, later age of menarche, fewer menses per year since menarche, a lower-fat diet, and a leg-length discrepancy compared with their non-stress fracture counterparts. Contrary to expectations, dietary calcium intake, restrictive dietary patterns, use of the oral contraceptive pill, training parameters, height, weight, and total body-fat mass did not differ between those who did and did not sustain stress fractures. Cobb et al. (2007) were not able to say that oral contraceptives reduced stress fracture rates, but did report that the direction of effect for long-distance runners taking the oral contraceptive pill was in the direction of it being protective.

For spinal stress fractures, it is key to recognise that the spine does not fully mature until around age 25, leaving the posterior elements of the spine relatively weak and susceptible to injury with repeated stress such as pars injuries (Kukreja et al. 2020).

References

Bennell, K. L., Malcolm, S. A., Thomas, S. A., Reid, S. J., Brukner, P. D., Ebeling, P. R., & Wark, J. D. (1996). Risk factors for stress fractures in track and field athletes. A twelve-month prospective study. The American journal of sports medicine, 24(6), 810–818. https://doi.org/10.1177/036354659602400617

Cobb, K. L., Bachrach, L. K., Sowers, M., Nieves, J., Greendale, G. A., Kent, K. K., Brown, B. W., Jr, Pettit, K., Harper, D. M., & Kelsey, J. L. (2007). The effect of oral contraceptives on bone mass and stress fractures in female runners. Medicine and science in sports and exercise, 39(9), 1464–1473. https://doi.org/10.1249/mss.0b013e318074e532

Finestone, A., & Milgrom, C. (2008). How stress fracture incidence was lowered in the Israeli army: a 25-yr struggle. Medicine and science in sports and exercise, 40(11 Suppl), S623–S629. https://doi.org/10.1249/MSS.0b013e3181892dc2

Kukreja, M., Hecht, A., & Tortolani, P. (2020). Spondylolysis and spondylolisthesis in the adolescent athlete. Seminars in spine surgery, 32(3), 100804. https://doi.org/10.1016/j.semss.2020.100804