Today, I'll point out two studies that explore the relationship between exercise and mortality. It should be no surprise to hear that regular exercise is a good thing, even (or perhaps especially) in later life. The overwhelming weight of evidence demonstrates that maintaining an exercise program over the years is, alongside the practice of calorie restriction, the most reliable and effective approach to modestly slow the consequences of aging. That statement will not continue to be true for many more years, but even as the first rejuvenation therapies arrive, those based on clearance of senescent cells, it will remain the case that exercise delivers some degree of benefits - and for free. Perusing numerous studies of exercise and life span conducted over the years, the difference in life expectancy between a sedentary lifestyle and a moderately active lifestyle is probably in somewhere in the lower end of the five to ten year range. The quality of health in the last decades of life is also notably different between the two extremes.
Most human studies only show correlations. It is the animal studies that prove causation - that it is the exercise producing the difference in health and longevity, not a matter of those in better shape who were going to live longer anyway also being more likely to exercise. As the use of cheap, lightweight accelerometers to measure activity has spread, and research groups are becoming better at mapping the dose-response curve for exercise, it is beginning to appear to be the case that even those of us who are moderately active - say, by following the long-standing 150-210 minutes per week guideline - are probably exercising too little to come close to the 80/20 point. Double that might be more on the mark. But of course, the current consensus is a moving target, and one should be wary of any attempt to extract pinpoint accuracy from epidemiology. It is better mined for rough guidelines, and in the studies here those rough guidelines tend towards a recommendation for more vigorous activity and more strength training.
Physical inactivity is estimated to cause as many deaths globally each year as smoking. Current guidelines recommend ≥150 minutes per week of moderate-intensity aerobic physical activity (PA) and muscle-strengthening exercises on ≥2 days per week. These guidelines are based primarily on studies using self reported moderate-to vigorous-intensity PA (MVPA). Technological developments now enable device assessments of light-intensity PA (LPA) and sedentary behavior, and well-designed studies with such assessments that investigate clinical outcomes are needed for updating current guidelines. Here, we present data from the WHS (Women's Health Study).
Women were mailed a triaxial accelerometer and asked to wear it on the hip for 7 days (except during sleep and water-based activities) and then to mail back the device. A total of 17,708 women wore their devices. Of 17,466 devices recording data (242 devices failed), 16,741 (96%) had data from ≥10 hours/day on ≥4 days. Women were followed up through December 31, 2015, for mortality, with deaths confirmed with medical records, death certificates, or the National Death Index. We examined the associations of total volume of PA (total accelerometer counts per day), MVPA (minutes per day), LPA (minutes per day), and sedentary behavior (minutes per day) with mortality using proportional hazards regression.
At baseline, the mean age was 72.0 years, and mean wear time was 14.9 hours/day. The median times of MVPA, LPA, and sedentary behavior were 28, 351, and 503 minutes/day, respectively. During an average follow-up of 2.3 years, 207 women died. Total volume of PA was inversely related to mortality after adjustment for potential confounders. For MVPA, there also was a strong inverse association. This association persisted in sensitivity analyses that excluded women with cardiovascular disease and cancer and those rating their health as fair/poor or deaths in the first year.
Three main findings emerged. First, we observed a strong inverse association between overall volume of PA and all-cause mortality. Although this inverse relation is not novel, the magnitude of risk reduction (≈60%-70%, comparing extreme quartiles) was far larger than that estimated from meta-analyses of studies using self-reported PA (≈20%-30%). Second, the strong inverse association for overall volume of activity was attributable primarily to the strong inverse association between MVPA and mortality. Third, we did not find any associations of LPA or sedentary behavior with mortality after accounting for MVPA.
This study is one of the first investigations of PA and a clinical outcome using newer-generation accelerometers capable of measuring activity along 3 planes. Using triaxial instead of uniaxial data increases the sensitivity for recognizing PA, detecting more time in LPA and less time in sedentary behavior. This study provides support for the 2008 federal guideline recommendation of MVPA, but it does not support either increasing LPA or decreasing sedentary behavior for mortality risk reduction.
The largest study to compare the mortality outcomes of different types of exercise found people who did strength-based exercise had a 23 percent reduction in risk of premature death by any means, and a 31 percent reduction in cancer-related death. "The study shows exercise that promotes muscular strength may be just as important for health as aerobic activities like jogging or cycling."
Public health guidance includes strength-promoting exercise (SPE) but there is little evidence on its links with mortality. Using data from the Health Survey for England (HSE) and Scottish Health Survey (SHS) from 1994-2008 we examined the associations between SPE and all-cause, cancer, and cardiovascular disease mortality. The core sample comprised 80,306 adults aged ≥30 years corresponding to 5,763 any cause deaths (681,790 person years).
Following exclusions for prevalent disease/events in the first 24 months, participation in any SPE was favorably associated with all cause (0.77) and cancer mortality (0.69). Adhering only to the SPE guideline of (≥2 sessions/week) was associated with all-cause (0.79) and cancer (0.66) mortality; adhering only to the aerobic guideline (equivalent to 150 minutes/week of moderate intensity activity) was associated with all-cause (0.84) and cardiovascular disease (0.78) mortality. Adherence to both guidelines was associated with all-cause (0.71), and cancer (0.70) mortality. Our results support promoting adherence to the strength exercise guidelines over and above the generic physical activity targets.