That physical activity can benefit health should come as no surprise; but it s not always clear how much is enough (or too much), and if the rules apply to older folks as much as to younger people. Two studies just published in JAMA Internal Medicine investigated these questions.
Dr. Hannah Aren from the National Cancer Institute and colleagues investigated whether increasing exercise amount is linked to a decreased risk of mortality. In particular, they wanted to determine if the Physical Guidelines for Americans, which advise a minimum of 75 and 150 minutes of vigorous or moderate activity per week, had an upper threshold for benefits. Were there benefits to reaching these levels. Further, if one were more active than these recommendations, would that be harmful to health?
To answer these questions, the investigators pooled data from 6 separate studies performed on individuals in the United States and Europe. In all, there were nearly 700,000 men and women included in these studies, and their median age was 62 years. They were followed for a median period of about 14 years.
Compared to people who reported no physical activity, those who exercised at all but who didn t meet the minimum recommended activity levels displayed a 20 percent lower risk of death. And they found the risk was 31 percent lower for those participating in 1 to 2 times the minimum activity levels, and a 37 percent decrease in risk for those involved in 3 to 5 times the minimum level. Importantly, there was no indication of harm in people reporting 10 or more times the minimum level of activity. The authors of this study concluded that healthcare professionals should encourage inactive adults to perform leisure time physical activity and do not need to discourage adults who already participate in high-activity levels.
In the second study, Dr. Klaus Gebel from James Cook University in Queensland, Australia and colleagues examined in more detail how the proportions of vigorous and moderate exercise could affect the risk of death in middle-aged and older adults.
The investigators performed a prospective study on over 204,000 Australians aged 45 to 75 years old. They examined associations between risk of death and different contributions of moderate and vigorous activity (MVPA) to total activity.
Their evaluations found that for individuals who reported any MVPA, the greater the proportion of vigorous activity, the lower the risk of death. For example, compared to those reporting no vigorous activity, for those who reported less than 30 percent of MVPA as vigorous activity, the risk was decreased by 9 percent, while for those whose vigorous activity was more than 30 percent of total activity, the risk was lower by 13 percent.
These authors concluded Among people reporting any activity, there was an inverse dose-response relationship between proportion of vigorous activity and mortality. They also encouraged the dissemination of this information in clinical and public health guidelines.
ACSH s Dr. Ruth Kava had this comment Of course one should be in reasonable health to engage in vigorous activity, but taken together these two studies further underline the importance of regular activity to health. One cannot determine from these studies whether the exercise was the cause of reduced mortality, since they were both observational. However, there seems to be no reason to discourage large amounts of vigorous exercise even in older folks, and certainly these results support advising couch potatoes to get up and move.