Regular physical exercise has been highly recommended for the prevention and rehabilitation, but there is still controversy over the optimal dose to produce maximal cardiovascular and renal benefits. Former athletes were reported to have longer lifespans but also more susceptible to coronary artery calcification and atrial fibrillation. On May 17, 2022, a new analysis aiming to examine the relationship between exercise dose and the risk of coronary artery disease (CAD), chronic heart failure (CHF), myocardial infarction (MI), and chronic renal failure (CRF) in adults was published in the European Journal of Preventive Cardiology. It was based on the National Health and Nutrition Examination Surveys (NHANES) data covering the timeframe from 2011 to 2018, when the questionnaires on physical activity were basically the same. Physical activity data were collected using self-reported questionnaires. A typical recording of weekly exercise activity in daily life was used to define the exercise habit. Metabolic equivalent hours (h) (MET·h = MET score × exercise time) were calculated as a quantitative index of exercise. Participants without exercise (MET·h/week = 0) were allocated to the never exercise group (NE group). Given that the accurate cutoff value for the optimal exercise dose is unknown, the remaining participants were assigned to four exercise groups with exercise doses of 0 < MET·h/week≤10 (low exercise group, LE group), 10 < MET·h/week≤50 [moderate exercise group (ME) group], 50 < MET·h/week≤100 [vigorous exercise group (VE) group], and MET·h/week > 100 (ultra-vigorous exercise group (UVE) group].
A total of 21 098 samples were included in the analysis. Individuals with regular exercise habits were younger and had lower body mass index (BMI), systolic blood pressure (SBP), triglyceride, HbA1c, fasting glucose, and blood urea nitrogen levels as well as higher education levels and annual income. Serum creatinine was only significantly lower in the ME and VE groups compared with the NE group. In the highest dose of exercise group, the participants with the youngest age exhibited higher SBP, serum creatinine and lactate dehydrogenase, and lower HDL levels, suggesting that the important markers did not decrease as the exercise dose increasing. After adjusting for age, sex, smoking status, occupation, income, alcohol consumption, and education level, we noted that only participants in the VE group had the best risk reduction effect of CAD [odds ratio (OR) 0.584, 95% CI: 0.403–0.823], CHF (OR 0.443, 95% CI: 0.286–0.658), MI (OR 0.602, 95% CI: 0.426–0.832), and CRF (OR 0.611, 95% CI: 0.434–0.840). Interestingly, the UVE group also obtained risk reduction in all the four diseases, whereas the efficacy was less compared with the VE group.
That is, exercise dose between 50 and 100 MET h/week, which equals to vigorous exercise for 6.25 to 12.5 h (or moderate exercise for 12.5 to 25 h) per week, should be optimal for reducing the risk of CAD, CHF, MI, and CRF. Continuing to increase the exercise dose is still protective but brings less benefits.