You're tired, busy, and the couch is calling your name ... Nice try, but those are fairly flimsy excuses for skipping a workout. Suck it up and get to the gym, already.

However, there are legitimate reasons for sitting out a day or several. "Sometimes your body may need time to heal or rest," says Dr Moira McCarthy. That's when powering through your usual workout could set the stage for illness or injury.

How can you tell if you need a break? For starters, the following six reasons.

You're coughing or wheezing

If you're just fighting mild cold symptoms, like a runny nose or scratchy throat, moving may boost your circulation and help you feel better. It could also be a symptom of COVID-19, so skip the workout and get a test instead.

If that comes back negative, exercise scientist Jessica Matthews suggests: "Just make sure that you do something low-intensity and don't push your body too hard."

If the symptoms are below the neck—in other words, in your chest—the coughing, wheezing, or difficulty catching your breath could signal a more serious infection and definitely give you an excuse for staying in bed until you feel better.

It's past midnight, and you're planning to hit the gym at 6am

Don't pat yourself on the back for dragging yourself out of bed on five hours' sleep. Cutting your slumber short—even for exercise—may do more harm than good. Research shows that even one night of sleep deprivation can affect your health: It raises levels of stress and hunger-inducing hormones. Make it a regular habit, and you'll increase your risk for a number of conditions, including heart disease.

"If you can, switch your workout to that afternoon or evening," says Matthews. "Or make an effort to sneak in more movement throughout your day, like taking a walk during lunch."

You're running a fever

A high temperature is an instant stop sign. That's because exercise can raise your internal temperature, which can slow the body's healing process. If you show any signs of the flu, such as chills or body aches, send yourself to bed instead of the treadmill.

Again, it could also be a symptom of COVID-19. So skip the workout and get a test instead. 

Your muscles still hurt from yesterday's—or the day before's—workout

That's a sign of delayed-onset muscle soreness (DOMS). A tough workout causes tiny tears in muscle tissue—and that's good, because the repairs will make you even stronger. However, exercising with stiff, aching muscles can compromise your form.

"You may favour one side during a movement, or not be able to go through a full range of motion," says Matthews. The result: You're more likely to hurt yourself. If only one part of your body—say your legs—are complaining, you can work your arms, for example. But if you're sore all over, hang up your sport shoes for a day or two.

Your knee or foot aches every time you go for a jog

"Persistent pain is a red flag that something's wrong," says McCarthy. You could be sliding into—or already have—a strained muscle or overuse injury, such as plantar fasciitis or even a stress fracture. McCarthy suggests resting the area until you can exercise pain-free. If the problem persists, see a health care provider, such as a physio. 

© Prevention Australia