Exercise levels for subjects in the lowest, middle, and highest tertile of overall physical activity are given in Table . Almost half of the study participants were exercising less compared with before the diagnosis of CHD. Overall, more subjects reported moderate or greater intensity exercise during leisure than at work, but only 33% of subjects were currently working. Differences in physical activity levels by age and sex were small, and there was no association with time since CHD diagnosis.
Physical activity levels in the STABILITY study population
Importance of symptoms
Subjects reporting low physical activity were more likely to be limited ‘a lot’ by common daily activities such as walking 100 m or 1 km, and climbing one flight of stairs than those who were more active (Table ). However, most sedentary subjects did not report ‘a lot’ of limitation with these activities. The least active subjects were more likely to be limited ‘a lot’ by symptoms, the most common of which were fatigue, shortness of breath, and arthritis. However, for the least active tertile, only 12% of subjects were limited ‘a lot’ by shortness of breath compared with 7% for the most active tertile (P < 0.001). Seven percent of the least active tertile reported they were limited ‘a lot’ by chest discomfort or tightness, compared with 5% of the most active tertile of subjects (Table ).
Relationships between physical activity and symptoms during exercise
Variables associated with low physical activity
Increasing age and being male were associated with low physical activity in both the unadjusted and fully adjusted models (Table ). Low physical activity was also associated with more frequently reported limitation by symptoms during exercise, poorer self-reported general health, and a larger number of co-morbidities. The strength of these associations was weaker in the fully adjusted model with the exception of sex. There was a modest association between depressed mood and low physical activity, but not in the fully adjusted model. Obesity was associated with lower physical activity, in both the unadjusted and adjusted models.
Predictors of low physical activity and of taking less exercise compared with before diagnosis of coronary heart disease
The majority of subjects (65%) had never participated in a cardiac rehabilitation programme, and these subjects were more likely to report taking less exercise. Living in a lower or upper middle income country compared with a high income country was associated with higher odds ratio for low physical activity in the unadjusted but not in the adjusted model. This may be the result of collinearity between this parameter and country. East Asian/Japanese races had more than twice the odds ratio for low physical activity compared with Whites.
Change in activity since diagnosis of coronary heart disease
Overall, 46% of subjects had reduced their level of exercise compared with before the diagnosis of CHD, while 34% had increased their physical activity (Table ). Factors associated with a greater likelihood of decreasing exercise since diagnosis of CHD were similar to those for low physical activity. The strongest associations with reduced activity were for poorer self-reported health and symptoms during exercise. Living in a middle compared with a high income country was also strongly associated with a greater likelihood of decreasing exercise. There were also modest independent associations for Asian and Black race groups.
There were large international differences in proportion of subjects reporting low physical activity, with subjects living in Asia and Latin America reporting the lowest levels of physical activity. (Figure , Table ) There were also large international differences in the proportion of subjects who decreased physical activity since CHD diagnosis, and in attendance at a cardiac rehabilitation programme (Figure , Table ). Subjects living in Russia and several Eastern European countries reported the greatest decreases in physical activity after CHD diagnosis. Fewer subjects living in Latin America, Asian, or Eastern European Countries had attended a cardiac rehabilitation programme compared with those living in North America, Western Europe, Australia, and New Zealand.
Proportion of study subjects who reported low levels of physical activity (<24MET.h/week) by country.
International differences in reported physical activity, decrease in exercise after coronary heart disease diagnosis, and cardiac rehabilitation attendance for STABILITY study participants assessed at baseline
Proportion of study subjects in each country who attended a cardiac rehabilitation program and who reported decreasing their physical activity since diagnosis of coronary heart disease.