What Happens When You Do The Same Exercise Every Day?

Learn why working the same muscles repeatedly is counterproductive, wasting your time and inviting injury.

There's nothing wrong with being a gym rat. Working out regularly and with intensity is key to getting bigger, stronger and faster. However, there's a fine line between dedicated and self-destructive—the latter often called overtraining. Taking breaks and days off is ultimately better for you than working out all day, every day.

That said, the specifics behind overtraining have always been a little hazy. If you've ever done the same exercise or hit the same muscle group on consecutive days, someone's probably told you you're overtraining. But why? If I want to build a bigger, stronger upper body, why shouldn't I bench press every day? Or, if I want to build a stronger and more explosive lower body, why shouldn't I squat every day? What happens in your body when you exercise with this type of behavior?

STACK talked with Dan Hutchinson, exercise physiologist and performance coach for D2K Training, John Mikula, exercise physiologist for the Department of Defense, and Dr. Mike T. Nelson, exercise physiologist and member of the American College of Sports Medicine, to find out what happens when you don't give your body a break.

The Science

There's nothing wrong with wanting to get better. Every athlete is told to set goals, so knowing what you want to improve is a good thing. Every athlete also knows the only way to achieve his or her goals is to work hard. This is true. But an issue arises when an athlete has a goal in mind—for example, increasing his or her Bench max and getting a stronger upper body—and decides the best way to achieve it is to perform intense upper-body lifts every day.

When you strength train, you induce tiny tears in the muscle fibers of the muscles you're working. This is normal. After you work out, your body sends "satellite cells" to repair these muscles. The cells use amino acids from protein as their building blocks. If you've got enough high-quality protein in your diet, your body will be able to repair the torn muscle fibers by making them thicker and stronger than before—which is how you gain strength and size.

By constantly assaulting the same muscle groups without rest, however, you destroy those muscle fibers before they have the time to repair. You don't let your body move past the demolition phase and into the building phase. Without rest and recovery, your muscles cannot fully grow.

"We look at the example of Bench Pressing every day at high intensities, or volumes, as detrimental to the periodization principles of building and recovering," Hutchinson says. "At the cellular level, it comes down to a lack of adequate time to repair the damaged cells."

The implication of what Hutchinson says is that at some point you're wasting time and preventing yourself from making meaningful gains.

Nelson says, "Each time you strength train, you create micro trauma to the muscle tissue itself. The body then works to repair this muscle and build it up so it's just a bit stronger. This process takes time—research states from anywhere as short as 24 hours to as long as 72 hours, depending on intensity. If you're hitting the same muscle group day in and day out, you're causing more damage before the previous damage can be completely repaired. So, you're working really hard and gradually getting less and less results.

"Every time you train, think of it like digging a small hole. Your body then fills the hole back in and adds just a bit more for good measure (which means strength gains). If you're digging at a faster rate than the hole can be filled, you're going backwards instead of forward."

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Begging for Injury

Repeating the same exercise or exercises every single day also opens the door to injury. "Repeating exercises such as Bench Press or Power Clean every day can be a pathway to the number one cause for fitness injuries, and that is creating 'over-use,'" Mikula says. "The body does not have ample time to recover from the training stimulus or is unable to deal with the amount of localized stress being placed on an isolated part of the body."

Doing 100 reps of Curls every day is a bad idea, not only because your muscle fibers won't recover and get bigger, but also because you leave yourself extremely susceptible to injury. Basically, you're doing something that won't get you stronger while making yourself more injury-prone in the process. Doesn't sound like a good idea, does it?

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Working Smart

It's hard to admonish someone for working too hard in the gym. Dedication and intensity are hallmarks of great athletes. But you also have to be smart about how you spend your time. If you do the same exercises or hit the same muscle groups in the weight room on a daily basis, you're not getting bigger or stronger—you're inviting injury and wasting time.

"The facts are, if we continually break down the same muscle fibers, or supporting muscle fibers, eventually the individual will plateau, become injured or notice a decline in performance—at least that's what the research and practical experience has shown," Hutchinson says.

You can surely work hard, but you've also got to work smart. By using split days and giving major muscle groups a rest, you'll stay healthier, get stronger, build more muscle and avoid wasting time. "If your goal is to get bigger arms, for example, I would recommend doing some compound and isolation exercises three days a week with at least one day of rest in between," Nelson says.

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John Mikula, MA, CTRS, CEP (ACSM), CSCS, TRX, is an exercise physiologist working with the United States Air Force.  Mr. Mikula does not speak on behalf of the U.S. Air Force or the U.S. Department of Defense, and the opinions expressed are his own.  

Photo Credit: Getty Images // Thinkstock