Chapter 32
Lifestyle+ — 23
There’s one thing you don’t want to do for any prolonged period: sit. While I was initially skeptical of the link between time sitting and risk of mortality, and the frequent notification alerts on smartwatches, many prospective studies have found consistent results, such as one with over 480,000 participants followed for thirteen years. People who sat mostly at work had an associated 16 percent higher all-cause mortality, and 34 percent increased cardiovascular mortality, after adjusting for potentially confounding factors. This report and others suggested that increasing physical activity can help mitigate the detrimental effect of sitting, but better to limit time of sitting and derive the benefit of physical activity.
We’re now understanding the synergic interaction of exercise and diet better. In people with prediabetes achieving a 10 percent weight loss by calorie restriction and multimodal exercise (movement + resistance), there was a much greater improvement in insulin sensitivity than by calorie restriction alone. The mechanism by which exercise protects against obesity, the metabolic syndrome, and type 2 diabetes is getting unraveled, with the discovery of a metabolite (N-lactoyl-phenylalanine, Lac-Phe) that is induced with exercise, and reduces food intake.
With respect to optimal timing of exercise, our clock proteins and circadian rhythm come into play, with some studies suggesting late afternoon or early evening is better than the morning for exercise performance while others find morning is preferred. Exercise in the fasted state may have some benefit for lipid utilization and glucose regulation. Overall, there is no clear perfect time, but good support exists for an individual to maintain the same pattern, be it early or later in the day.
Now for an inspirational message about exercise: it’s never too late! Consider the story of Richard Morgan, a ninety-three-year-old man, who was reported in the Journal of Applied Physiology. In his seventies, he took up regular exercise for the first time in his life using a rowing machine in his backyard shed, with an average forty-minute workout each day. In parallel, he eats a high-protein diet and does two strength training sessions per week with dumbbells, lunges, and curls. He has now won four world championships for indoor rowing, and cumulatively rowed the equivalent of ten times round the globe. Extensive assessment at the University of Limerick in Ireland, where his granddaughter is a researcher in the physiology lab, showed his 165 pounds of body weight comprised of 80 percent muscle and 15 percent fat. His maximal rate of oxygen uptake, VO2, is similar to those reported for young adults. Peak heart rate during exercise was 153 beats per minute, which would be closer to what we’d expect in a fifty-year-old. This remarkable case study tells us there’s no age limit that precludes getting in shape to counter age effects, and even the potential for using exercise as a means of reversing aging.