PHYSICAL FITNESS, PHYSICAL ACTIVITY AND CORONARY HEART DISEASE RISK PROFILE

The objective of this study was to determine the relative contributions of physical activity and physical fitness to the coronary heart disease (CHD) risk factor profile. The sample consisted of 253 males and 226 females 30–59 y of age from the Québec Family Study. The sum of six skinfolds, submaximal work capacity (PWC150), quadriceps muscle strength and the number of sit-ups performed in 60 seconds were used as indicators of physical fitness. Estimates of physical activity, including daily energy expenditure, moderate-to-vigorous physical activity, and time spent watching television were derived from a three-day activity record. The risk factor profile consisted of fasting HDL-C, LDL-C, triglycerides, glycemia, and mean arterial blood pressure. Bivariate correlations between physical activity and physical fitness variables and each component of the CHD risk profile were low to moderate. Canonical correlation was used to determine the multivariate association among physical activity, physical fitness and the risk factor profile. Canonical correlations reveal that in men 23.0% (r = 0.48, p < 0.0001) of the variation in the CHD risk profile was accounted for by physical fitness, and 6.5% (r = 0.26, p = 0.12) by physical activity. In women 22.9% (r = 0.48, p < 0.0001) and 7.9% (r = 0.28, p = 0.053) of the variance in the CHD risk profile was accounted for by physical fitness and physical activity, respectively. Thus, the results suggest that physical fitness is more related to the CHD risk factor profile than physical activity in both men and women. The difference in the strength of the relationships could potentially be explained by differences in measurement error, as physical fitness is typically more accurately measured than physical activity. Further research should be aimed at ascertaining the best predictors of the CHD risk profile, using more precise measures of physical activity and other lifestyle components. The Québec Family Study is currently supported by the Medical Research Council of Canada.