Keywords: exercise, death, physical activity (PubMed Search)
"The Tortoise and the Hare" fable has been used as a metaphor for the epidemiological differences between slower, low-intensity exercise versus faster, high-intensity physical activity.
"Current physical activity recommendations are predicated on the idea that both the hare and the tortoise can win the race for better health, but the provocative studies give an edge to the hare's higher-intensity approach,"
Regular physical activity is associated with significant health benefits, including decreased risk of cardiovascular disease, cancer, and all-cause mortality.
Traditional research has focused on exercise volume (150 minutes/week) over intensity.
Two recent studies looked at the benefits of shorter bouts of vigorous activity at higher intensities.
A recent large population-based cohort study of middle-aged adults used objective measurement of activity (wrist accelerometer) over self-reporting to investigate the role of exercise intensity and CV health.
Higher intensity physical activity is associated with lower rates of incident CVD.
This makes theoretical sense as greater stimulation will result in greater physiologic CV adaptations resulting in overall improved CV fitness.
For example. the authors extrapolate that an ambling 14-minute stroll has roughly the same cardiovascular benefits as an up-tempo 7-minute walk at a brisk pace.
Increasing the total amount of activity is not the only means of achieving health goals which can be met with raising overall intensity.
Vigorous physical activity is a time-efficient means to achieve overall health benefits of exercise.
A recent study (Ahmadi et al., 2022) involved 71,893 older adults with a mean age of 62.5. Authors found that quick bursts of vigorous physical activity throughout the day can lower older adults' risk of premature death by 16% to 27%, depending on daily frequency and weekly totals (from 15-20 min/week up to 50-57 min/week).
For example, doing one two-minute burst of high-intensity exercise every day for a total of 14 minutes per week was associated with an approximately 18% lower risk of all-cause mortality. The authors also found that doing as little as one to nine minutes per week of vigorous activity in quick bursts versus doing no vigorous activity was associated with significantly lower all-cause mortality risk over five years.
Exercise may not need to be a planned hour-long session at the gym for our middle-aged and older population. Accruing small amount sporadically over the day/week is an attractive option to reap the CV benefits of exercise. Existing exercise guidelines will need to be modified with future research to pinpoint the optimal exercise intensity and duration for adults in different stages of life.
Dempsey et al., 2022. Physical activity volume, intensity, and incident cardiovascular disease, European Heart Journal, Volume 43.
Ahmadi et al., 2022. Vigorous physical activity, incident heart disease, and cancer: how little is enough?, European Heart Journal, Volume 43, Issue 46