What is the Goldilocks Level for Physical Activity ?
The 2018 physical activity guidelines recommend that Americans perform 150 to 300 minutes weekly (min/wk) of moderately intense physical activity (MPA), such as brisk walking, or 75 to 150 min/wk of vigorous physical activity (VPA), such as jogging. These recommendations are based on multiple epidemiological studies, but questions remain: is this enough exercise, and what happens if you do more? The latter question is prompted by studies suggesting that lifelong endurance athletes have more coronary atherosclerosis plaque, mild myocardial scarring, and atrial fibrillation than their sedentary counterparts even though athletes live longer.1
Lee et al used data from the Nurses’ Health Study and the Health Professionals Follow-Up Study to examine the relationship between leisure-time physical activity (PA) and mortality.2 The study has many strong attributes; it included 116,221 individuals and, during 30 years of follow-up, identified 47,596 deaths. PA was assessed every 2 years using a questionnaire measuring lifetime PA, and, in contrast to most epidemiological studies of PA, mortality was the primary outcome.
The results reaffirm the 2018 guidelines but with a twist. Participants adhering to the guideline-recommended MPA or VPA levels had 19% to 25% and 15% to 31%, respectively, lower all-cause, cardiovascular disease (CVD) and non-CVD mortality rates. However, going beyond the guidelines had more benefit. Those reporting their performance of two to four times the recommended amount of MPA (ie, 300–599 min/wk) or VPA (150–299 min/wk) had 3% to 13% and 2% to 4% lower all-cause, CVD, and non-CVD mortality rates than those simply meeting the guidelines.
There was no evidence of significant risk from these higher levels of activity, but the graphs of mortality are interesting and worth further study. All forms of mortality decreased sharply and progressively with increasing MPA, but the decrease was less impressive for VPA as there was a nonsignificant upward trend in CVD mortality with increasing VPA. Indeed, the maximal benefit for VPA was around 150 to 300 min/wk, or twice the guideline-recommended physical activity, with little further benefit beyond this. The curve for CVD mortality and VPA never gets back to baseline to form a “U-shaped” curve but forms a “reverse-J” pattern instead.
Now, to reiterate the usual disclaimer: epidemiological studies are not randomized clinical trials, and people who choose to exercise may be inherently different from those who do not. However, this study adds to the data that you should encourage your patients to choose to exercise. They should try to achieve the 2018 physical activity guidelines, but they must also know that a little more is a little better and that they do not have to kill themselves with VPA to benefit more. More min/wk of MPA is better, but for VPA, 150 to 300 min/wk seems to be just right.
References
- Eijsvogels TMH, Fernandez AB, Thompson PD. Are There Deleterious Cardiac Effects of Acute and Chronic Endurance Exercise? Physiol Rev. 2016;96(1):99–125. https://journals.physiology.org/doi/full/10.1152/physrev.00029.2014
- Lee DH, Rezende LFM, Joh HK, et al. Long-Term Leisure-Time Physical Activity Intensity and All-Cause and Cause-Specific Mortality: A Prospective Cohort of US Adults. Circulation. 2022 Jul 25. doi: 10.1161/CIRCULATIONAHA.121.058162. Online ahead of print. https://www.ahajournals.org/doi/10.1161/CIRCULATIONAHA.121.058162
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