You may recall a study from a few years back suggesting that increasing level of exercise in later life, after a low level of exercise in earlier life, removes a perhaps surprisingly large fraction of the negative consequences of that low level of exercise. This is at least the case when it comes to age-related mortality. Nonetheless, in that study, maintaining a high level of exercise across life was still shown to be much better for health than only beginning high levels of exercise in later life.
Today's open access paper reports on a similar study, but here the metrics are specifically focused on measurements of frailty, such as grip strength. The interesting portion of the outcome is that the people who moved from low levels of exercise to greater exercise look similar to those that always maintained that higher level of exercise. The conclusion that one could make from this is that frailty as presently observed in the wealthier parts of the world is a large part a consequence of inactivity, and that at least that portion of the problem is reversible given sufficient effort.
Increasing evidence reports the benefits yielded by regular physical activity (PA) on the motor function in older people by preserving mobility, muscle strength, and balance. However, there is a methodological limitation that PA are evaluated at single time-point (primarily the baseline level) or short time-scales without considering the long-term dynamic nature of PA behavior. Group-based trajectory modeling (GBTM) allows grouping of subjects presenting with similar baseline values and longitudinal patterns of change according to their direction and magnitude. Using this method, some studies have detected different PA trajectories among older adult cohorts. Three studies examined the association of PA trajectories with mortality in older adults. But, there isn't an investigation of the temporal association of long-term PA participation trajectories with subsequent motor function changes and incident frailty.
Therefore, the main objectives of this study were to investigate different trajectories of long-term PA participation over a 6-year span by the GBTM and evaluate their associations with subsequent motor function decline and incident frailty in middle-aged and elderly adults. Our hypotheses are that older adults maintaining PA over time will have a slower motor function decline and a lower risk of incident frailty compared with persistently inactive subjects or those reducing PA levels, and that increasing PA even at older ages promotes healthy aging characterized by reduced motor function decline and incident frailty.
Five distinct trajectories of long-term PA participation were identified in the aging cohort, including persistently low-active trajectory (N = 2,039), increasing active trajectory (N = 1,711), declining active trajectory (N = 216), persistently moderate-active trajectory (N = 2,254), and persistently high-active trajectory (N = 2,007). Compared with the persistently low-active group, the participants in persistently moderate- and high-active groups experienced significantly decelerated grip strength decline, decreased gait speed decline, and faster chair rises after multiple-adjustment. Similarly, participants maintaining moderate- and high-active PA were also associated with a lower risk of incident frailty (multiple-adjusted hazard ratio 0.70 and 0.42 respectively), compared with those with persistently low PA. Notably, the participants with the increasing active trajectory got similar health benefits as those with persistently moderate and high levels of PA.
Thus in conclusion, in addition to persistent PA, increasing PA was linked to a slower decline in motor function and lower risk of incident frailty in the cohort. Our findings suggest that regular PA is never too late.