If some is good, more must be better, right? Not when it comes to painkillers, alcohol, and—according to a bevy of new research—exercise. You don't have to take up residence in the gym to fall victim to overtraining. Here's how your seemingly solid workout schedule could be screwing with your fitness gains.

Sure, the concept of overtraining is nothing new. After all, your muscles don't grow stronger in the gym; it takes hours or even days after your workout session to build back up. But what is surprising is just how little exercise might be way too much when it comes to losing weight and getting in super-fit shape. But where do you draw the line between just enough exercise and going overkill?

Recent research from the University of Copenhagen suggests that breaking point could be any more than half an hour per day. In the study, young men in their 20s and 30s who exercised for 30 minutes each day for 13 weeks lost about 40 percent more weight than those who worked out for a full hour each day.

Researchers believe the reason is two-fold:

1. The men who exercised an hour a day compensated with too many extra calories, counteracting their weight loss.

2. Outside of the gym they were largely inactive, most likely because they were burnt out.

In that vein, a new study presented at the American College of Sports' annual meeting found that the average person spends 39.7 percent of their waking hours being physically active (i.e. walking to the store or raking leaves) on the days they don't work out, compared to only 8.8 percent activity outside of the gym on days they do.
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"Overtraining is rough on your entire body—it takes its toll both mentally and physically," says personal trainer Mike Donavanik. In the fitness (or lack thereof) department, exercising too much results in muscle loss, decreased strength, increased body fat, lowered testosterone levels, weakened immunity, more injuries, insomnia, and constant muscle soreness. The result: Little to no muscle gain and fat loss—and even poor overall health.

In fact, people who work out too hard for too long are often less healthy than sedentary people, and have an increased risk of death compared to moderate exercisers, according to the British journal Heart. When you exercise, your body produces free radicals in a process called oxidative stress. While the body is equipped to deal with some (about an hour's worth of) oxidative stress, long, intense workouts cause more than your body's antioxidant reserves can handle, predisposing you to chronic diseases, according to researchers.

"You're essentially pushing the body past its limits," says Donavanik. "Your body keeps operating on debt. It's constantly trying to catch up, but it never gets the opportunity to."

Here are three ways to make sure your body gets the rest it needs so you can get fitter, faster:

1. Take the day off

"Set aside at least one day a week where you do absolutely nothing and just let your body recoup," Donavanik says. Also, let at least 48 hours pass before re-working any one muscle group so that it has time to heal before you stress it again.

2. Change things up

Your workout routine should be a constant rotation of hard, easy, different. Scheduling "hard" and "easy" workout days can add variety and needed rest into your workout, while trying new exercises—or even a class from time to time—can keep you from working the same muscles over and over again, he says.

3. Show your muscles some love

Between workouts, recovery is king. Feed your muscles right: Protein, whole grain-carbohydrates, omega-3 fatty acids, calcium, zinc, and vitamins A, C, and D all help promote cell growth and muscle tissue repair. What's more, making sure you snooze for eight hours a night can help your muscles grow back stronger—as can massages. (Score!) Donavanik recommends visiting your masseuse every two to four weeks.