The first thing to ask yourself if you’re wondering whether you’ve exercised too much is: “Why am I exercising?” says Dr Benjamin Levine, a professor of internal medicine at the University of Texas Southwestern Medical Center, US, and director of the Institute for Exercise and Environmental Medicine at Texas Health Dallas, US.

If your goal is to improve your health and reduce your risk of a range of conditions from diabetes to heart disease to cancer, then two-and-a-half to three hours of moderate to vigorous exercise per week gets you the vast majority of benefits, Levine says. “Once you get past five hours per week or so, you’re not exercising for health, you’re exercising for performance.”

And when you’re exercising for performance — whether it’s to get stronger in the gym, run a marathon or improve your tennis game — it’s possible to stress your body beyond what it can bounce back from, says Kristen Dieffenbach, an exercise scientist and director of the Center for Applied Coaching and Sport Sciences at West Virginia University, US.

For athletes, the purpose of training is to induce a so-called training response, she says. You work out, and your body responds by getting fitter, stronger and faster. These improvements don’t happen during the workout itself but occur during the recovery period. That’s when your body repairs the damage brought on by hard exercise, like microtears in your muscle fibres, and makes adaptations, like increasing the energy-producing mitochondria in your cells.

As long as your body is able to keep up with this repair work, your workouts will continue to aid your performance, Dieffenbach says. But when the stress from your workouts builds up beyond your capacity to recover, you have entered the zone of too much, known in the sporting community as overtraining.

The most reliable signs that you’re exercising too much come from your subjective feelings of well-being, Dieffenbach says. If you’re suddenly tired all the time, or workouts that used to seem easy feel hard or your performance has dropped unexpectedly (like your running times have gotten slower without explanation or your daily walk is taking much longer than usual), it might be time to ramp down and rest, Dieffenbach says.

Other classic signs of overtraining include trouble sleeping, feeling run-down and not being able to shake minor colds and other respiratory infections. “Sometimes you have to back off to move forward,” Dieffenbach says.

If you find you’re having to force yourself to do workouts you used to enjoy, or feeling guilty about not exercising enough, these are signs that you’ve overdone it. This is especially true if the feelings linger for more than a few days, Dieffenbach says.

On the other hand, if you’re finding that your love of exercise is becoming more of an unhealthy obsession, that’s something to pay attention to as well, says Szabó Attila, a health psychologist who studies exercise addiction at Eotvos Lorand University in Budapest, Hungary. An exercise addiction can occur when someone feels compelled to do physical activity, even if they are in pain or injured. If you’ve put exercise before your relationships, work and everything else, Attila says, that’s a sign that it’s become too much.

One of Attila’s colleagues, Mark Griffiths, a psychologist at Nottingham Trent University in Britain, has developed six criteria for health providers to use when screening patients for exercise addiction:

• Exercise is the most important thing in my life

• Conflicts have arisen between me and my family and/or my partner about the amount of exercise I do

• I use exercise as a way of changing my mood (e.g. to get a buzz, to escape)

• Over time I have increased the amount of exercise I do in a day

• If I have to miss an exercise session I feel moody and irritable

• If I cut down the amount of exercise I do, and then start again, I always end up exercising as often as I did before

To classify as an addiction, a person would need to meet all six criteria, and that’s rare, Griffiths said. But a lot of people exhibit problematic exercise that doesn’t quite reach the level of an addiction, he added. For instance, those who go to work and function normally, but then come home and neglect their family so that they can go to the gym and workout — that’s still a problem.

Which brings us to the ultimate answer to our question: yes, it’s possible to exercise too much. And you’ll know you’re doing it when it’s breaking down your body, making you sick or injured or adversely affecting the rest of your life. When it stops making you feel good and enriching your life, it’s time to cut back.