NEW YORK • Exercise researchers and physicians have some blunt advice for those of us aiming to return to regular exercise now, after months spent sheltering at home during the coronavirus pandemic.

Start slowly, they suggest, and then rev up your workouts, also slowly. Many of us, admittedly, have been sedentary during the pandemic.

According to data from the company Fitbit, which makes activity trackers, American adults tended to be over 10 per cent less active after the stay-at-home mandates began in March than they were in January. This inactivity leaves most of us less fit than during those halcyon days of last year, with predictable consequences when we surge back to our favourite sidewalks, paths and gyms.

"We already are seeing new patients hobbled by overly enthusiastic recent workouts," said Dr Monica Rho, chief of musculoskeletal medicine at the Shirley Ryan Ability Lab in Chicago and an associate professor at Northwestern University's Feinberg School of Medicine.

But there are steps we can take to ease our way back into regular exercise safely, she and other exercise experts say. Most involve patience.

"You can't go from zero to 60 as soon as things open up," Rho said.

In epidemiological studies of sports-related injuries, the risks of harm skyrocket when people abruptly increase the amount or intensity of their workouts.

Instead, Rho said: "Start at no more than 50 per cent of the exercise you were doing before Covid-19."

If you previously ran 8km, she says, plan on covering 3km or 4km, at a slower pace than before.

Thread in some preparatory squats, too, she advises.

"When you haven't been exercising, you lose muscle mass."

Speed its regain and stave off leg and back injuries with basic body weight exercises, she says, such as squats, lunges, planks and hip raises, which can be completed in small spaces and require only a few minutes.

Cyclists also should cobra stretch, she recommends.

"Most of us have been sitting much more during the pandemic," she said, contributing to back tightness, which is amplified by the bent-over posture of cycling.

So, before riding, lie prone and push your chest up from the ground until your upper body resembles a striking cobra. Hold for 30 seconds and repeat a few times.

Dawdle through any resumption of weight training, too, said Brad Schoenfeld, an associate professor of exercise science at Lehman College in New York, who researches resistance exercise.

"If you have been doing almost no training during the pandemic," he said, "plan to start at 50 per cent of the volume and intensity of your prior workouts when you return to the gym."

Expect some muscle twinges after these preliminary sessions, especially a day or two later. But sudden or increasing pain during exercise is a call to stop and return home, both Rho and Schoenfeld say.

After the first week, gradually lengthen or intensify your training.

Schoenfeld suggested returning to about 75 per cent of your former lifting loads by the second week of renewed resistance training and 100 per cent by week three.

Endurance athletes may require a month or longer to safely reach earlier training levels, Rho said.

NYTIMES