The aim of this study was to evaluate whether a relationship exists between impaired glucose tolerance and both habitual physical activity and physical working capacity. Sixty-five apparently healthy subjects with impaired glucose tolerance (according to criteria of the European Association for the Study of Diabetes), age range 40-59 years, and 125 subjects with normal tolerance, sex, age and body mass index matched, were selected among the participants in a health examination survey. They filled in a questionnaire on daily physical activity during work and leisure time and performed an exercise test on a cyclergometer. No difference in physical activity at work was recorded between the groups, but the proportion of individuals who were physically active during leisure time, was significantly lower among the subjects with impaired glucose tolerance (8.1% vs 19.7%; P less than 0.05). Moreover these subjects had a higher heart rate during and 1 min after the standard exercise test (113.4 +/- 15.8 vs 105.7 +/- 17.7 beats/min, P less than 0.005; mean +/- SD). This supports the hypothesis that low physical activity is a risk factor for impaired glucose tolerance, independent of mutual effect of obesity.