Health effects of recreational running in women. Some epidemiological and preventive aspects.

Estimated maximum oxygen uptake of middle-aged nonelite road race entrants is around 45 to 50 ml/kg/min, which is 40 to 100% higher than values from the female general population. Endurance training, low bodyweight, and nonsmoking of runners explain part of, but not the whole, difference in aerobic capacity observed between athletes and the general population. Sedentary women can improve cardiorespiratory fitness through aerobic exercise programmes, and the women with the lowest level of initial fitness have the highest proportional improvement following training. Regularly exercising women have a significantly reduced risk of fatal and nonfatal coronary events, and low cardiorespiratory fitness is associated with an increased risk of death and nonfatal stroke. The influence of habitual running on the female blood lipid profile is not clear. Cross-sectional studies have found elevated HDL cholesterol concentrations in distance runners, but intervention studies on the effect of jogging on lipid and lipoprotein levels have provided equivocal results. A higher level of physical fitness is associated with a lower risk to subsequently develop hypertension. Experimental studies have shown that moderate intensity aerobic exercise (40 to 60% VO2max) is able to reduce blood pressure significantly in hypertensive subjects. An athletic lifestyle may be associated with a reduced risk of adult-onset diabetes mellitus (via an exercise-induced increase in insulin-sensitivity), and with a reduced risk of cancers of the reproductive system, breast, and colon. Recreational running is also correlated with better weight control. Surveys of recreational and elite distance runners show a great variability in the prevalence of secondary amenorrhoea, between 1 and 44%. Environmental factors determining the risk of amenorrhoea in runners are low body fat content, mileage, and nutritional inadequacy, with low intakes of calories, protein, and fat. Amenorrhoeic athletes in their third and fourth decade have lower vertebral bone density, which is improved after resumption of menses but does not completely reach age-specific average values. Regardless of menstrual status, the effectiveness of exercise to maintain bone mass throughout life is an important issue. Habitual exercise is associated with increased bone density of the spine both in premenopausal and postmenopausal women. Several controlled training studies suggest that postmenopausal women may at least retard their bone loss with regular aerobic exercise. Running-related injuries and complaints are common in recreational joggers, even though the reported 1-year incidence, varying between 14 and approximately 50%, depends on injury definition. Mileage and a history of previous running injury are known risk factors.(ABSTRACT TRUNCATED AT 400 WORDS)