Bone-stress injuries occur on a continuum from low-level bone stress, which may be mildly symptomatic (think the beginnings of ‘shin splints’), through to stress fractures, whereby an athlete may have difficulty weight bearing on the affected limb.
For triathletes, common regions for bone-stress injuries include the tibia (shin), femur, sacrum and foot bones (metatarsals and the midfoot). And they develop when bone damage accumulates from repeated loading cycles with insufficient recovery time in between.
Historically, the focus for prevention and treatment has centred on the load to the bones, e.g. training programmes, an athlete’s biomechanics, footwear and running terrain.
Consideration also needs to be given to the ability of an athlete’s bones to absorb training loads, which can include genetics, medical conditions, sporting history, energy availability, vitamin D and calcium levels, bone density, and even life stress and sleep quality.
Energy availability is a key consideration, with many triathletes unintentionally training through a state of ‘low energy availability’. Blood samples can be taken to monitor sex hormone levels and menstruation cycle disturbances among women. If you fall into this category, your risk of sustaining a bone-stress injury can increase 6.5-fold.