Sex differences in relationships between habitual physical activity and health in the elderly: practical implications for epidemiologists based on pedometer/accelerometer data from the Nakanojo Study.

We review sex differences in the relationship between habitual physical activity and health in the elderly, with particular reference to pedometer/accelerometer data from the Nakanojo Study. Maximal aerobic power, walking speed and habitual physical activity are 10-30% greater in men than in women. This reflects not only biological but also socio-cultural and environmental factors, with the latter becoming dominant as age advances. It implies a need for sex-specific thresholds of moderate activity. Overall health is associated with both the year-averaged daily step count (the best indicator in women) and the year-averaged daily duration of physical activity >3 metabolic equivalents (METs) (the best indicator in men). In both sexes, the threshold ranges of step count and/or duration of activity >3 METs associated with a reduced prevalence of health problems are: 4000-5000 steps/day and/or 5-7.5 min/day for impaired mental and psychosocial health, such as a depressed mood state and a poor health-related quality of life; 7000-8000 steps/day and/or 15-20 min/day for markers of aortic arteriosclerosis, osteoporosis, sarcopenia and poor physical fitness; and 8000-10,000 steps/day and/or 20-30 min/day for components of the metabolic syndrome, especially hypertension and hyperglycemia. Irrespective of sex, both the intensity and the total volume of physical activity are influenced by stressful life events, such as a partner's death, and immediate meteorological factors, particularly precipitation and mean ambient temperature, underlining the need for long-term measurement of activity patterns. These findings have practical implications for those who engage in epidemiological studies and/or design health promotional programs for the elderly.