Bone stress injuries & RED-S Blog

Between one third and two thirds of competitive endurance runners have a history of bone stress injury (BSI)1-3. A BSI demonstrates the inability of bone to endure repetitive loading, which ultimately results in bone tenderness and pain, and structural fatigue1. Bone stress injuries are a concern for marathon and long-distance runner’s due to their frequency, length of rehabilitation, and their tendency to recur1.

Females have been found to be at a higher risk of BSI’s as a result of the Female Athlete Triad (FAT)4. The FAT is a complex condition that involves three components: 1) low bone mineral density, 2) low energy availability with or without an eating disorder, 3) menstrual dysfunction4-6. More recently, the term Relative Energy Deficiency in Sport (RED-S) has been used to expand the concept of the FAT to recognise other outcomes, and the inclusion of male athletes4. Research has suggested that an athlete with one or more components of the FAT has an increased risk of developing bone stress injuries4-6. Individual’s with RED-S and components of the FAT experience short and long-term impacts on both health and athletic performance4. Given that one component of the FAT is low bone mineral density, this increases an athletes risk of bone injuries such as stress reactions and potentially stress fractures. Additional risk factors for stress reactions include underlying poor bone health, menstrual dysfunction, low BMI, compulsive exercise, eating disorders, and prior BSI’s4. It is crucial to detect RED-S early in order to prevent long-term health consequences, and improve performance4.

A BSI generally occurs prior to a diagnosis of RED-S/FAT, and so health care professionals need to be able to identify those individuals at risk7. It is common that an athlete may require cessation from sport following a BSI in order to correct their energy deficit, and to allow recovery from the BSI7. However, to allow improvements in bone health and prevent recurrence of BSI’s, exercise is an important aspect of the rehabilitation process. Optimal rehabilitation from a BSI involves a balance between performance of appropriate loading and rest from aggravating activities1. Evidence suggests that key areas to focus on include strength, endurance, and control at the knee, ankle, and the hip1.

It is well established that improvements in bone mineral density occur as a result of mechanical load the bone is subjected to9. Athletes with reduced bone mineral density should undergo resistance training programs at least 2-3 days per week7,8. Positive outcomes on bone strength has been demonstrated following periods of progressive high intensity RT and multi-directional impact activity, both of which should be incorporated into end stage strengthening rehabilitation when treating reduced bone mineral density8. Management should also include weight bearing conditioning in the form of a graduated return to running program once appropriate.

Other important considerations are the potential presence of faulty running mechanics which could hinder the healing process or contribute to repeated BSI’s1. As bone loading relates to ground reaction forces, therapy interventions that reduce GRF and improve shock absorption during running may reduce BSI recurrence1. Such gait retraining techniques include altering stride rate, and modifying initial contact1.

While most BSI’s readily heal following a period of activity modification and a progressive return to loading, strength training and running activities, there is a need to address underlying causative factors to prevent BSI recurrence1.Management of the FAT requires input from a multidisciplinary team to ensure that the athlete’s psychological wellbeing and energy availability is maintained7. Patients require ongoing review with sports physicians, and physiotherapists, and may benefit from review by a sports dietician and sports psychologist. Evidence has suggested that management of exercising women with low BMD should include resumption of menses, optimising weight gain, and increasing energy availability5. In order to increase energy availability, an individual’s energy status should be normalised through modifications to exercise training and diet5. Studies have shown that restoring or normalising body weight is the key to successful resumption of improved bone health and normal menstrual function5.

References:

  1. Warden SJ, Davis IS, Fredericson M. Management and prevention of bone stress injuries in long-distance runners. J Orthop Sports Phys Ther. 2014;44(10):749.765. doi:10.2519/jospt.2014.5334
  2. Biz C, Berizzi A, Crimì A, Marcato C, Trovarelli G, Ruggieri P. Management and treatment of femoral neck stress fractures in recreational runners: a report of four cases and review of the literature. Acta Biomed. 2017;88(4S):96-106. doi:10.23750/abm.v88i4-S.6800
  3. Pegrum J, Crisp T, Padhiar N. Diagnosis and management of bone stress injuries of the lower limb in athletes. BMJ (Int Ed). 2012;344(7854):35-40. doi:10.1136/bmj.e2511.
  4. Mountjoy M, Sundgot-Borgen J, Burke L, et al. The IOC consensus statement: beyond the Female Athlete Triad—Relative Energy Deficiency in Sport (RED-S). Br J Sports Med. 2014;48:491-497. doi:10.1136/bjsports-2014-093502
  5. De Souza MJ, Nattiv A, Joy E, et al. 2014 Female Athlete Triad coalition consensus statement on treatment and return to play of the Female Athlete Triad: 1st International conference held in San Francisco, California, May 2012 and 2nd International Conference held in Indianapolis, Indiana, May 2013. Br J Sports Med. 2014;48:289. doi:10.1136/bjsports-2013-093218

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