gms | German Medical Science

Numerous studies have shown protective effects of physical activity against cardiovascular diseases [Ref. 1], [Ref. 2], [Ref. 3], [Ref. 4], [Ref. 5] but measurements of physical activity were mostly restricted to one or few points of time. The objective of this analysis was to examine the lifetime patterns of physical activity and their relation to cardiovascular disease.

In the baseline examination of the ESTHER study, a prospective cohort study with 9954 participants age 50 to 74 years at recruitment, detailed lifetime histories of physical activity, body weight, smoking as well as the presence of major cardiovascular events (myocardial infarction and stroke) and age of their onset were documented by the study participants. Two levels of physical activity were measured: light activities (walking, cycling, light manual work) and heavy activities (sudatory sports, heavy manual work). For each intensity, the average number of hours per week were documented for age 20, 30, 40 and 50 years. For each decade, three categories of either heavy or light physical activity were constructed: 0 hours, > 0 - < 40 hours or ≥40 hours per week. The third category was chosen to reflect work related physical activity. To operationalise lifetime patterns, a sum score of physical activity from 20 years through 50 years of age was used with the following categories: never involved in physical activity, > 0 - < 40 hours, always 40 hours or more per week of physical activity between age 20 and 50 years. These categories were generated separately for light and heavy physical activity. For each decade body mass index (BMI, body weight in kg/ squared body height in m) and pack years smoked were calculated. The endpoint of interest was the occurrence of a major cardiovascular event (MCVE) after the age of 50. Participants with a MCVE before the age of 50 (n=193) were excluded to avoid potential bias form disease related change of physical activity. To examine the association between life time patterns of light and heavy physical activity and MCVE, multiple logistic regression was used controlling for known confounding factors like age, sex, smoking, BMI and education. Results basically did not change when both variables of physical activity were simultaneously included into the model.

1328 study participants (18.1%) reported no heavy physical activity for all decades, whereas 1307 (17.8%) reported heavy physical activity for 40 hrs or more per week for 20 trough 50 years of age. No involvement in light physical activity at all was documented by 1006 participants (13.7%) and 40 hours or more per week by 963 (13.1%). A MCVE after 50 years of age was experienced by 569 study participants (6.1%). Whereas only 64 persons (4.8%) who documented no heavy physical activity from 20 through 50 years of age and 244 (5.2%) with heavy physical activity of > 0 - < 40 hours per week had a MCVE after the age of 50 years, there were 139 heavy physically active persons (10.6%) who experienced a cardiovascular event. After adjustment for age, sex, lifetime course of smoking and BMI as well as education, participants with no heavy physical activity at all or ≥40 hours per week had an increased risk for MCVE of 29% compared with study participants who were involved in > 0 - < 40 hours per week (Odds Ratio (OR): 1.29, 95% Confidence Interval (95% CI): 0.96 – 1.74, and. OR:1.29, 95% CI: 1.02 – 1.62, respectively).

Only 52 participants (5.4%) who were involved in light physical activity for 40 hours or more throughout adulthood, but 93 (9.2%) who were not physically active and 302 participants (5.6%) with > 0 - < 40 hours per week experienced a cardiovascular event after the age of 50. Compared to study participants who were involved in > 0 - < 40 hours per week of light physical activity, participants with no light physical activity at all had a 21% higher risk for a MCVE (OR: 1.21, 95% CI: 0.94 – 1.55) adjusting for sex, lifetime course of smoking and BMI and education, participants who were involved in ≥40 hours per week of light physical activity also had a 20% higher risk (adjusted OR: 1.20, 95% CI: 0.90 – 1.52).

Based on our results, the absence or the excess of physical activity until the age of 50 years seems to be a risk factor for MCVE in terms that both are associated with a increased risk for MCVE after the age of 50 years. The results of our study, therefore, add new information to the still ongoing debate [Ref. 1], [Ref. 2], [Ref. 3], [Ref. 4], [Ref. 5] about the optimal amount and intensity of physical activity and suggest that the benefits of physical activity may be a matter of dose, especially under a life course perspective taking work related physical strain into account.