science of us

In Defense of the Micro Workout

Taking the stairs. Photo: Florian Kuettler/Getty Images/Westend61

For a story on heart rate, I started wearing a chest strap monitor yesterday, and in the evening I took a very brief run — about eight minutes. It felt a little pathetic, but my heart-rate did skyrocket, and it seems marginally less pathetic in light of today’s updated government recommendations for exercise, which allow workouts of less than ten minutes to count toward recommended weekly goals.

As the JAMA report’s authors write, “bouts of a prescribed duration are not essential,” and short bursts — taking the stairs, parking farther from a destination — can accumulate. Or, as they repeat throughout: “moving more and sitting less will benefit nearly everyone.”

The other main development since the Physical Activity Guidelines were last issued (in 2008) is that preschool-age children (ages 3–5) are now advised to get at least three hours of combined light, moderate, and vigorous aerobic exercise, “to enhance growth and development.” (Or, their caretakers are advised to keep that in mind.)

Mostly, though, the guidelines have stayed the same, with the weekly recommendations for an adult being 150–300 minutes (2.5–5 hours) of moderate-intensity aerobic exercise (brisk walking, yard work) or 75–150 minutes (1.25–2.5 hours) of vigorous-intensity aerobic exercise (running, bicycling) — or some combination the two. Muscle-strengthening activities (weight lifting, resistance training) are also recommended at least twice a week. Pregnant and postpartum women are advised to get 150 minutes (2.5 hours) of moderate-intensity aerobic activity, and adults 65 and older are advised to incorporate balance training into their routines, too (lunges, walking backward).

If you’re wondering “But what does that look like?” the report also includes a fun three-minute video. (“Walking is a good first step.”)

Not that these guidelines are necessarily doing much: Despite the advice, apparently only 26 percent of men, 19 percent of women, and 20 percent of adolescents report meeting the recommended minimums. And in the United States, 10 percent of premature deaths and $117 billion in health-care costs are associated with “inadequate physical activity.”

On a positive note, the guidelines do endorse fitness technology — such as step counters, wearable devices, and fitness apps — as useful potential counters to our general lethargy. Anecdotally based on my shame-driven brief run last night to spike my heart-rate, I can back this up. This isn’t exactly the same, but I once kept going to an exercise class in part because they gave out free socks and took your picture when you crossed certain thresholds.

In Defense of the Micro Workout