How to tell when your body needs a break

Story highlights

  • When you exercise, you're causing a bit of trauma to the body
  • If you're not allowing the body to recover, you're causing yourself more harm than good

(CNN)We've all been there: Just when you're getting into the groove of your new workout obsession — wham! Suddenly your knee is killing you, or your quads are hurting in a way that just doesn't feel right. Yep, you've over-worked yourself into an injury — and are suddenly wondering why you didn't take a few more rest days along the way.

    So what gives? First, it's important to understand physiologically, what happens when we exercise. "When you exercise, you're causing a bit of trauma to the body," says Noam Tamir, Certified Strength and Conditioning Specialist and owner of TS Fitness New York City. Essentially, when you exercise, you create micro-tears in your muscles. Then, when your muscles repair, they grow stronger.
    However, Tamir says, "The more you work, the more you train, the more stress you're putting on the body. If you're not allowing the body to recover, you're causing yourself more harm than good." After all, exercise doesn't just impact your muscles — it impacts your digestion, kidney function, hormone regulation, and more. Before injury strikes, listen to these five signs that might indicate your body needs some time off.

    1. You're always sore.

    Sure, a bit of muscle soreness (hello, DOMS) after a particularly strenuous workout is totally normal, especially if you're newer to exercise or you're switching up your routine. But if you're exercising regularly, you shouldn't constantly be feeling sore, says Tamir. Depending on the muscle group, you should always give your muscles 24 to 48 hours to recover between training sessions, and if you still feel sore, it's possible you're overtraining. According to Rice University, "Overtraining can best be defined as the state where the athlete has been repeatedly stressed by training to the point where rest is no longer adequate to allow for recovery." Persistent muscle soreness, getting sick more often, or frequent injuries are all physical symptoms of overtraining. Fortunately, recovery is simple — just take it easy for a few days!

    2. You're constantly tired or moody.

    Moodiness, depression and fatigue are also indications that you might be overtraining. Most of us have heard that exercise is supposed to make us happier, thanks to a rush of endorphins — a stress-fighting chemical — in the brain. (Fun fact: Endorphins also help prevent you from noticing the pain of exercising. Thanks, brain!) However, those endorphins are also accompanied by cortisol, a stress hormone. And when cortisol levels remain high for an extended period, they take a toll on mental health.

    3. Your heart rate is abnormal.

    One of the best ways to gauge if you've been overtraining is to check your heart rate, Tamir says. "I'll take my resting heart rate in the morning. If I'm above my normal, then I know that my body is not really ready for a hard workout that day. That's one of the best ways to judge your readiness to exercise." Rice University notes that a lower-than-normal heart rate can indicate overtraining, too. Ready to experiment with this method? Try taking your resting heart rate daily to figure out what's normal for you.

    4. You're stiff all the time.

    If a few too many