Chapter 30
Lifestyle+ — 21
The problem with using steps as a proxy for physical activity is that it doesn’t represent discrete exercise time, a nonoccupational effort. The recommendation of 150 minutes per week of moderate physical activity is meant to consist of dedicated sessions, not incidental starting and stopping, with a sustained increase in heart rate, to promote aerobic cardiovascular fitness.
Over decades as a cardiologist, I would only stress the need for aerobic exercise, omitting the importance of strength, resistance, and balance training. That was a mistake, especially with all the evidence that has come out in recent years highlighting the loss of muscle mass as we age, and its prognostic importance. Aerobic conditioning should be considered just one of the two dimensions of exercise that are requisite. This activity could be push-ups, pull-ups, sit-ups, squats, lunges, and using weights, bands, or machines, ideally getting at all muscle groups (arms, chest, abdomen, legs, hips, and back). A goal for building muscle power after taking the sit-to-stand test, which is how many times you can do that in thirty seconds (eleven to twelve for women and men over age sixty-five), can be achieved with squats, hinges, and pushes plus light weights, starting with five-pound dumbbells. Isometric exercises holding tension in the body, like wall squats for eight minutes a day, three times a week, lower blood pressure as effectively as aerobic exercise or high-intensity interval workouts, as seen from a review of 270 randomized trials. Unlike aerobic activity, the studies that have looked at the relationship between resistance training and all-cause mortality suggest sixty minutes per week may represent a plateau.
Muscle mass and strength start to go down at about fifty years of age. Between ages sixty and ninety years, men lose about 33 percent of their muscle mass and women about 26 percent. Muscle strength parallels that decline. Preserving core strength is essential for good posture and avoiding back pain and joint inflammation, all while promoting mobility and balance.
The associated reduction in all-cause mortality of about 25 percent (fig. 3.6) with sixty minutes per week of resistance training doesn’t tell the whole story. Benefits extend to associations with less cardiovascular and cancer mortality, less visceral fat, better sleep quality, more bone density, enhanced balance, and improved mental well-being. A randomized trial of one year of resistance training in older adults compared to a nonexercizing control group found durable muscle strength benefit out to four years.
Figure 3.6. The relationship of duration of resistance training and risk of all-cause mortality. Adapted from Prathiyankara Shailendra et al., “Resistance training and mortality risk: A systematic review and meta-analysis,” American Journal of Preventive Medicine 63, no. 2 (August 2022): 277–85, https://doi.org/10.1016/j.amepre.2022.03.020.