By Dr Dan Laptoiu, MD, Bucharest, Romania

Mediating factors

Age: There is little evidence to suggest that age has any bearing on the risk of sports injury. Although bone density decreases with age thus reducing the bone resistance to mechanical impacts, younger men universally are involved in more accidents than older men. This could be related to the amount and intensity of their activities.

Body Morphology: Although low bone density might be a factor in stress fractures due to weakened bone strength, there is little evidence of a greater risk of fractures in people with lower bone densities, except in women. No strong relationship between body size or composition and the risk of stress fractures has been demonstrated.

Gender: Females with menstrual disturbances appear to be at greater risk of sports injuries. Menstrual disturbances are more prevalent in female athletes than in the general female population. These include delayed menarche, anovulation, oligo- and amenorrhoea. The incidence of such disturbances among female athletes varies from ballet (52%), gymnastics (100%), distance running (65%), swimmers (31%), and team sports (17%).
Stress fractures appear to be more frequent in female athletes with such disturbances, with a 2 to 4 times greater relative risk compared to males. Lower estrogen levels associated with such conditions may have a negative effect on bone strength and retention of calcium in the bones. There is some evidence that oral contraceptive pills, which provide an exogenous source of estrogen, reduce the risk of stress fractures in runners.

Training Levels: Bone stress injuries often occur after increasing the level of physical training activity. This occurs more frequently among individuals who are out of condition.
Running is associated with more leg stress injuries than walking, as it produces a much greater (up to 6-fold) impact load on the skeletal bones. Jumping-type sports such as basketball, volleyball, and ballet dancing, produce impact loads 6-fold higher than walking, with an increased risk of tibia strains and fractures.

Preventive measures for avoiding sports injuries

• Physical conditioning and preparation
• Appropriate activity and training level
• Warm-up/cool-down before and after exercise
• Proper protective equipment, such as proper shoes
• Alternate different sports activities