We know what happens when you don't get enough exercise -- muscles get weak, energy droops, mood and sleep patterns go haywire and flab creeps in. But what happens when you get too much physical activity? Need a hint? Re-read the first sentence of this paragraph.

Yep, overtraining can produce many of the symptoms of under-exercising (aside from the excess fat). But how do you know if you're pushing it too hard, especially when people like your pals at The Moving Crew are telling you to work out regularly and with some intensity?

In Depth About the Crew | Ask the Crew Susan Morse Health section assistant editor, hiker, kayaker, swimmer and dabbler in a variety of exercise regimens. » VISIT THE ARCHIVES Browse the Archives Recent Columns Discussion Transcripts Save & Share Tag This Article  Saving options 1. Save to description:  Headline (required) 2. Save to notes (255 character max):  Blurb 3. Tag This Article

That question was raised last week by a 61-year-old reader who worried about the safety of her running regimen -- an hour a day, five days a week. A trainer told her such a cardio schedule was likely degrading, not improving, her health and fitness.

If our reader feels good and has no injuries, her running routine is not excessive, says William O. Roberts, an associate professor in the Department of Family Medicine at the University of Minnesota Medical School and a past president of the American College of Sports Medicine.

Overtraining, Roberts says, is difficult to do, but it can happen. People who tend toward vigorous exercise, he advises, should take at least one day off per week and should alternate hard days with moderate-to-light days.

Because exercise tolerance varies so widely from person to person, Roberts and other experts decline to set time, frequency or intensity limits for training. But there are clear symptoms of overtraining to watch for, according to Roberts and the American Council on Exercise's Personal Training Manual:

?A consistently elevated resting heart rate. (Recognizing this, of course, requires that you know your historical rate for comparison.) The best time to measure your rate is first thing in the morning, before your heart rate starts fluctuating. "If you are 10 to 15 beats per minute higher than normal, take the day off," Roberts says. The higher rate could be your heart's working overtime to get oxygen to muscles insufficiently recovered from training abuse.

?Chronic fatigue or soreness in an overworked muscle, tendon, ligament or joint.