If you overtrain, you may develop chronic muscle fatigue, according to the American Council on Exercise (ACE). Your muscles and limbs may feel heavy, your heart rate may take longer to recover during training and you may lose agility and speed.
When you continue to push your body to its max workout after workout and when you don’t properly refuel, you have what’s called low energy availability, per the ACE, which means your body is consistently pulling from its own energy stores (your carbs, proteins and fat) to keep you moving.
As your body pulls from its own nutrient stores, you can’t respond productively to the exercise-induced stress. Muscles are broken down during exercise, becoming stronger and more resilient when they repair, Schumacher explains. But without enough fuel or recovery time, there’s no way for your muscles to strengthen.
“If you are exercising too much or with poor programming, your body will be unable to properly recover and adapt to the physical stress of working out,” Schumacher says.
While it’s rare, overexertion may also develop into rhabdomyolysis, a condition that results from the breakdown of muscle fibers, which leak into your blood, according to the American Academy of Family Physicians. If this goes unaddressed, rhabdomyolysis can cause heart issues and even kidney failure.
Exercising frequently throughout the week is totally OK, but make sure you’re taking recovery into account, too. Split training (working different muscle groups on different days) is one way you can avoid overexertion, according to the ACE. Mix up your exercise intensity, length and frequency, too.