Why To Exercise Today: Permission To Ease Back In, And The 10% Rule

So yes, I was bellyaching last week about being sidelined by injury and losing my exercise momentum. But after talking to Dr. Eddie Phillips, director of Harvard's Institute of Lifestyle Medicine, I realize that it wasn't exactly a momentum problem. I was discouraged because when I started back, after just a couple of weeks, I seemed to have lost significant fitness ground. I felt wimpy and guilty and weak, and thus unmotivated. Eddie helped.

When you stop exercising, he said, there's a psychological side and a physiological side. The psychological: It takes time for a habit like regular exercise to become truly ingrained. When he asks patients who truly have an exercise habit how they'd feel if they had to stop, they respond, "I'd be miserable." So my newly ramped-up exercise schedule may not have been fully established as a habit yet, but it can be in time.

And a lesson for next time: When addicts quit drugs, relapse is an expectable part of the process. Similarly, when people instill good new habits, they may relapse to their old couch potato ways. Eddie sometimes asks patients who are doing well with weight loss and exercise to write up a "relapse plan."

He says, "I want you to recapitulate all the things that got you on this road, and your values and support and hindrances, and write it on a piece of paper with a plan to get restarted." Then that plan can be put in an envelope and it's like "Break glass in case of emergency" — after a week of not exercising, a patient can break out the plan and do what it says.

Sounds worth a try. As for the physical side, Eddie said, when many people go back to exercising, they have a vision of their former abilities and try to go back too quickly, risking new injury. His rule of thumb, he said, is that you should never increase your load — distance or speed or intensity or number of reps — by more than 10 percent a week — "or, if you're recovering from an injury, we put you down to 5% a week."

"Easing back in is the right thing to do" said Eddie, whose Institute of Lifestyle Medicine belongs to the Harvard Medical School Department of Physical Medicine & Rehabilitation and is based at Spaulding Rehabilitation Hospital. His rule of thumb after an injury is to go down to "half the intensity, half the reps," and then go slowly back up again. "You'll get it back," he said. "It's all part of the process of becoming a habit."

There's no hard science on this, he said, but its beauty is that you can do the hard math, akin to calculating how quickly an investment will double if it grows at a certain rate a year, compounded. A runner hoping to do a marathon can figure out just how many weeks of 10% increases it will take to get to that level.

"People love numbers," he said — and it sounds like he does, too. "I can say, 'I wouldn't run a Memorial Day 10K, but by July 4 you'll be fine.'"

His rules of thumb, he said, "give you a chance not to get injured when you get back — and you get positive feedback because 'the doctor told me only to go back at half-speed, half-time,' so you're doing it, and then the physical and the psychological are working together."

I tried out his advice this morning, lowering my post-injury expectations, and yes indeed, my lighter workout lacked the guilt of backslide. I might even want to do it again tomorrow...

This program aired on March 8, 2011. The audio for this program is not available.

Headshot of Carey Goldberg

Carey Goldberg Editor, CommonHealth
Carey Goldberg is the editor of WBUR's CommonHealth section.



More from WBUR

Listen Live