We examined vigorous-intensity physical activity in relation to other potential risk factors for major chronic disease at baseline (). Men who reported more vigorous activity tended to have lower BMI, were less likely to smoke, and had higher intakes of omega-3 fatty acids and fiber.
Age-standardized characteristics* according to weekly vigorous activity at baseline (1986), Health Professionals Follow-up Study
During 22 years of follow-up, a total of 14,162 men (31%) developed a major chronic disease event. These included 4769 CVD events, 6449 cancer events, and 2944 deaths from other causes (e.g. pneumonia, kidney, or liver disease). There was a significant inverse association between total physical activity and risk of major chronic disease and total CVD, but no association with total cancer after adjusting for covariates ().
Hazard ratios of major chronic disease, cardiovascular disease, or cancer according to categories of vigorous-intensity and moderate-intensity activity, 1986 – 2008
In multivariable-adjusted analyses, moderate-and vigorous-intensity activity were inversely associated with risk of major chronic disease (P for trend <0.0001 for both; ). The hazard ratio (HR) for major chronic disease comparing ≥ 21 to 0 MET-hours/week of physical activity was 0.86 (95% confidence interval [CI]: 0.81, 0.91) for vigorous activity and 0.85 (95% CI: 0.80, 0.90) for moderate activity (). The results for total CVD were stronger, with HR comparing extreme categories of 0.78 (95% CI: 0.70, 0.86; P for trend < 0.0001) for vigorous activity and 0.80 (95% CI: 0.72, 0.88; P for trend < 0.0001) for moderate activity (). All associations were mildly attenuated after adjustment for BMI, but remained statistically significant. Using category medians, the HR for CVD corresponding to 10 MET-hr/wk of energy expended in vigorous activity was 0.93 (95% CI: 0.91, 0.95) compared to a HR of 0.95 (95% CI: 0.92, 0.97) for moderate activity (). In secondary analyses, we found replacing 10 MET-hr/wk of moderate-intensity activity with 10 MET-hr/wk of vigorous-intensity activity was associated with lower CVD risk (HR: 0.96, 95% CI: 0.93, 0.99, p = 0.02). Similar results were obtained for vigorous-intensity activity in the 2- and 4-year lag analyses, but results for moderate-intensity activity were attenuated suggesting benefits of moderate activity may be short-term. Vigorous activity was inversely associated with age-adjusted risk of total cancer (P for trend = 0.009; ), but no longer significant after covariate adjustment. Moderate-intensity activity was not associated with total cancer risk. We also repeated this analysis using “net” MET levels (i.e. subtracting MET-hours of resting metabolism from total MET-hours of activity) and obtained similar results.
We examined the association between individual activities and CVD risk (). In multivariable-adjusted analyses including all activities simultaneously in the model, running, tennis, and brisk walking were significantly associated with CVD (P for trend <0.0001, 0.004, and <0.0001 respectively) (). Running ≥ 5 hours/week was associated with a 46% risk reduction (HR: 0.54; 95% CI: 0.33, 0.89), tennis with a 28% risk reduction (HR: 0.72; 95% CI: 0.56, 0.92), and brisk walking with a 23% risk reduction (HR: 0.77, 95% CI: 0.68, 0.88) compared to men not participating in these activities ().
Hazard ratios for cardiovascular disease associated with average weekly hours of individual activities, 1986 – 2008
When we examined the more extreme categories of vigorous-intensity activity, higher amounts of vigorous activity were associated with a lower risk of major chronic disease and total CVD (). The multivariable-adjusted HR comparing ≥ 70 MET-hrs/wk of vigorous-intensity activity, which is equivalent to 10+ hours per week of vigorous exercise, to 0 MET-hrs/wk was 0.79 (95% CI: 0.68, 0.92; P for trend < 0.0001) for major chronic disease and 0.73 (95% CI: 0.56, 0.96; P for trend < 0.0001) for CVD (). In models further adjusted for BMI, the corresponding HR were 0.80 (95% CI: 0.69, 0.93; P for trend < 0.0001) for major chronic disease and 0.78 (95% CI: 0.60, 1.02; P for trend < 0.0001) for CVD. There was no association between vigorous activity and risk of total cancer.
Hazard ratios and 95% confidence intervals (CI) of major chronic disease (A), cardiovascular disease (B), and cancer (C) associated with weekly MET-hours of vigorous-intensity physical activity
We did find evidence of non-linearity when applying restricted cubic splines to the association between vigorous activity and major chronic disease (p < 0.0001) and CVD (p = 0.03). As shown in , for major chronic disease and CVD, much of the risk reduction is achieved in lower categories of vigorous activity; additional risk reduction is seen in higher categories, but with smaller magnitude.
We also investigated the association between vigorous-intensity physical activity and major chronic disease within subgroups defined by age (< 70 years, ≥ 70 years) and concurrent moderate-intensity exercise (≤ 1 hour/week, >1 hour/week moderate activity). An inverse association was observed in men younger than 70 and in men 70 years and older. There was, however, evidence of an interaction between participation in moderate activity and vigorous activity. Although significant in both groups, the inverse association between vigorous-intensity activity and major chronic disease was stronger among men reporting ≤ 1 hour/week of moderate activity compared to men reporting > 1 hour/week (P for interaction = 0.01) ().
Figure 2 Hazard ratios and 95% confidence intervals (CI) of major chronic disease associated with weekly MET-hours of vigorous-intensity physical activity, stratified by participation in ≤ 1 hour of moderate activity per week (A) or > 1 hour of (more ...)