Conceivably, you also could cram all of your exercise into long Saturday and Sunday workouts. In a 2017 study by Dr. Stamatakis and colleagues, people who reported exercising almost entirely on weekends were less likely to die prematurely than those who said they rarely exercised at all. But being a weekend warrior has drawbacks. “It is certainly not ideal to spend the workweek totally sedentary and then try to compensate” over the weekend, Dr. Stamatakis said. You miss many of the health benefits of regular exercise, such as improved blood-sugar control and better moods, on the days you do not work out, he said. You also increase your risk of exercise-related injuries.
Count your steps.
The exercise recommendations remain the same if you measure your exercise in steps instead of minutes. For most people, “150 minutes of exercise a week would translate into about 7,000 to 8,000 steps a day,” Dr. Lee said. In a large-scale new study by Dr. Lee and Dr. Ekelund of the relationship between steps and longevity, published in March in The Lancet, the optimal step count for people younger than 60 was about 8,000 to 10,000 a day, and for those 60 and over, it was about 6,000 to 8,000 a day.
Of course, these recommendations about steps and minutes focus on health and life spans, not physical performance. “If you want to run a marathon or a 10K race as fast as possible, you need much more exercise,” Dr. Ekelund said.
The recommended 150 minutes a week also may be too little to stave off weight gain with age. In a 2010 study of almost 35,000 women that was spearheaded by Dr. Lee, only those who walked or otherwise exercised moderately for about an hour a day during middle age maintained their weight as they became older.
So, if you have the time and inclination, move more than 30 minutes a day, Dr. Lee and the other scientists said. In general, according to her research and other studies, the more active we are, well beyond 30 minutes a day, the more our risks of chronic diseases drop and the longer our lives may be.
But any activity is better than none. “Every single minute counts,” Dr. Ekelund said. “Walking up the stairs has health benefits, even if it only lasts for one or two minutes, if you repeat it regularly.”
Gretchen Reynolds will be taking time off from the PhysEd column to work on a book. In the meantime, follow her on Twitter (@gretchenreynold) or look for her on the running trails and bike paths.