Longevity Briefs: Should We Be Exercising Like Hunter-Gatherers?

Longevity briefs provides a short summary of novel research in biology, medicine, or biotechnology that caught the attention of our researchers in Oxford, due to its potential to improve our health, wellbeing, and longevity.

Why is this research important: What is the optimal exercise routine for longevity? What types of exercise are the best, when should exercise be undertaken and for how long? A lot of effort has been dedicated to answering these questions, but with limited success. There seems to be a ‘j-shaped’ relationship between exercise volume and longevity, meaning that some amount of exercise is beneficial, but yields diminishing returns and may eventually become detrimental.

Most people at risk of overtraining are likely to be athletes undertaking a lot of vigorous physical activity (which is generally defined as activity that makes you breathe hard and fast). Yet our ancestors probably didn’t do much vigorous exercise. Studies of modern hunter-gatherers and of muscle anatomy suggest that we evolved to be endurance walkers and occasional endurance runners. With this in mind, how does moderate activity compare to vigorous physical activity in terms of longevity benefits for invested time?

What did the researchers do: In this review article, researchers looked at studies since 2011 covering the topic of exercise dose, type and life expectancy or cardiovascular health. The aim was to review the evidence linking the type, intensity and duration of exercise on health and longevity.

Key takeaway(s) from this research:

• When engaging in more than 2 hours of exercise per week, moderate physical activity seems to yield greater reductions in mortality than vigorous physical activity
• There is little further longevity benefit for vigorous activity beyond 2-3 hours per week
• Evidence suggests you should do about 40 minutes of strength training in addition to cardiovascular exercise, but that strength training in excess of 2 hour per week is potentially detrimental
• Incorporating flexibility and balance training into your routine may improve longevity
• Participation in social sports and more time spent in natural environments is associated with increased lifespan

The authors start with a landmark study of over 116 000 US adults who were followed up over 30 years. They highlight that while increasing time spent exercising per week was generally associated with reduced mortality, the effects of moderate activity and vigorous activity were very different. At lower durations of activity (up to around 2 hours per week), moderate and vigorous activity had similar effects on both cardiovascular and all-cause mortality. However, beyond this point, moderate activity was actually more effective than vigorous activity at reducing both forms of mortality. In the case of cardiovascular mortality, vigorous exercise resulted in a j-shaped curve where mortality began to increase again after around 3.5 hours per week, while moderate activity continued to yield increasing reductions in mortality.

The authors also looked at several meta-analyses of the effects of strength training on mortality. They suggest that the effects of strength training are independent of other forms of exercise, and strongly suggest that combining strength and cardiovascular training provides additional longevity benefits. These studies also suggest that the effects of strength training follow a j-shaped relationship where benefits lessen beyond around 40 minutes per week, and can increase one’s mortality rate beyond around 2 hours a week. However, people who undertake more strength training are also more likely to take anabolic steroids, which is associated with increased mortality. Misusing anabolic steroids in this way is illegal in most countries including the US, and many studies do not account for their use. Thus, the benefits of strength training may be underestimated here.

The review also touches on some other associations with increased life expectancy, such as flexibility, the ability to stand on one leg, the ability to stand from a sitting position without using supporting limbs, participation in social sports and time spent in natural environments. While all of the above are associated with reduced all-cause mortality, there’s less certainty about the direction of cause and effect, but there is perhaps something to be said for making a deliberate effort to improve/engage in these practices.