Fight Aging!

How much optimization of exercise is a reasonable goal, given what is presently known? Today's open access paper makes the fair point that our hunter-gatherer evolution matches us to a certain strategy, meaning a lot of moderate exercise leavened with a smaller amount of intermittent vigorous exercise. Epidemiological evidence supports the merits of a lot of moderate exercise, while suggesting that a lot of vigorous exercise doesn't add that much to the benefits, and it is actually possible to exercise too much.

The dose-response curve for exercise is one in which small amounts of effort are a great improvement over being sedentary, but after one hits a reasonable amount of moderate effort (maybe twice the recommended 150 minutes per week), further benefits taper off. Still, a great deal of thought and effort presently goes into the question of whether one can optimize type, timing, and degree of physical activity. One has to think that much of this is wasted effort, even while somewhere in there are a few grains of sense.

Training Strategies to Optimize Cardiovascular Durability and Life Expectancy

A landmark, long-term, prospective, cohort study evaluated the links between leisure-time physical activity duration and intensity with all-cause mortality and cause-specific mortality. The relationships between dose of exercise and risk of death during follow up were distinctly different for vigorous physical activity (VPA) than for moderate physical activity (MPA). First and foremost, very high levels of MPA reduced risk of cardiovascular disease (CVD) mortality and all-cause mortality substantially better than very high levels of VPA. Secondly, the reductions in CVD mortality and all-cause mortality were maximized at ~150 minutes/week of VPA; doses >150 minutes/week of VPA were associated with a plateau in all-cause mortality, and a modest but progressive loss of CVD mortality reduction at higher doses. In contrast, MPA reduced CVD mortality and all-cause mortality in dose-dependent, inverse relationships - the higher the dose of MPA the lower the number of deaths during the study.

For an individual whose goal is to decrease the risk of CVD and boost life expectancy, a routine of MPA appears to be adequate. Although chronically performing very high doses of VPA may attenuate some of the benefits bestowed by less extreme efforts, this is relevant for only about 2.5% of the US adult population. This is not to say that VPA is harmful; it substantially reduces all-cause mortality and CVD mortality compared to a sedentary lifestyle. Yet, the magnitude of the mortality and CVD risk reductions with high doses of VPA do not appear to be as substantial as for high doses of MPA. Chronically doing very high doses of moderate exercise reduced risks of all-cause mortality and CVD mortality at least two-fold better compared to chronically performing very high doses of vigorous exercise.

At the other extreme, a sedentary lifestyle - which affects about half of the U.S. adult population - is associated with worse health outcomes and diminished life expectancy. After sitting more than 60 minutes, the levels of blood glucose, triglycerides, and inflammatory markers begin to rise. Even light or moderate activity mitigates these adverse effects of sedentary behavior without unduly increasing orthopedic injuries or cardiac risks.

Throughout the last three million years of hominin evolution, our ancestors' existence necessitated a very physically active lifestyle. Adults would usually accumulate 14,000 to 16,000 steps/day, mostly in the form of walking three to eight miles, often while carrying objects such as wood, food, water, and children. Hunter-gatherer humans' daily subsistence required large amounts of MPA with smaller doses of interspersed VPA - this is the activity pattern for which we remain genetically adapted. This evolutionary template would seem to be a logical guide to structuring an ideal activity pattern for promoting optimum health and longevity.