EXERCISE, TRAINING AND INJURIES

Although exercise results in a number of well documented physical fitn ess and health benefits, accruing such benefits entails a risk of exer cise-related injuries. Musculoskeletal injuries occur frequently among fitness programme participants, runners, athletes, military recruits and others who engage in routine vigorous exercise. The same parameter s of exercise (intensity, duration and frequency) that determine the p ositive fitness and health effects of physical training also appear to influence the risk of injuries. Studies of runners and other physical ly active groups have consistently demonstrated that greater duration and frequency of exercise are associated with higher risk of injury. H owever, the sports medicine literature shows little association betwee n exercise intensity and injuries, a finding which may be misleading. The strongest and most consistent association reported exists between greater total amounts of exercise and higher risks of injury. This is not surprising, since the total amount of exercise is the product of t he intensity, duration and frequency of exercise. Recent military rese arch confirms the finding that higher volumes of running are associate d with higher rates of injury. Furthermore, the study of army recruits suggests that greater amounts of exercise not only result in greater risks of injury, but in some instances may also impart no additional i ncrease in fitness, a finding consistent with an earlier study of civi lian runners. Several military studies also demonstrate that those rec ruits who have been more physically active in the past are less likely to be injured during basic training. These military studies also docu ment a number of other factors, such as older age, smoking, sedentary jobs and lifestyle, high or low flexibility and high arches of the fee t, which may contribute to or modify the risks for exercise-related in juries. In conclusion, the present review suggests that, for activitie s such as running, specific parameters of exercise may contribute to t he overall risk of injuries in rough proportion to their contribution to the total amount of activity performed. Also, better knowledge of t he effects of the parameters of training and other factors on the risk s of exercise-related injuries is necessary to make more judicious cho ices about how to best achieve the benefits of exercise and to prevent injuries.