The Dangers of High Intensity Workouts

Here's why it's important to listen to your body when you work out.

Intense exercise programs like P90X, CrossFit and Insanity are some of the hottest workouts in fitness right now. Many are drawn to the challenging, mega-calorie-burning sweat sessions that leave their muscles sore and deliver fast results, and the supportive community keeps them coming back for more. But as enjoyable—and perhaps addictive—as high-intensity, out-of-the-box workouts may be, they can also be dangerous, especially for beginners or those with a history of injury. Here’s why.


High-Intensity Workouts Can Cause Kidney Damage


Rhabdomyolysis, the breakdown of muscle fibers and release of their toxic protein byproduct into the bloodstream, can result in kidney damage. It’s one major risk factor for those who jump right into these intense workouts glorified for their difficulty. Some of the most common causes of rhabdomyolysis (called “rhabdo” for short) include overexertion, extreme physical activity and trauma to the skeletal muscles—all of which can easily occur as a result of intense, strenuous exercise, marathon running or exercising in hot, humid weather.

Muscle membranes typically wrap around the muscle cell to keep everything intact. In athletic-induced rhabdo, the muscle membrane breaks down and eccentric contractions, shortening of the muscle while it’s being stretched, could be the culprit. An eccentric contraction, like a jump squat, strains the muscle membrane; the more tattered it becomes, the easier it is for its inner contents to leak out. When potassium and myoglobin, a protein found in muscle tissue, enter the bloodstream and reach the kidneys, the result can be deadly if not treated and causes permanent scarring on the kidneys.

Scary, right? Even more troubling is that some of the workout programs’ devotees have made a mascot of rhabdo, referring to it as “Uncle Rhabdo,” and treat working out hard to the point of vomiting as a rite of passage, saying they “met Pukey.” T-shirts have even been made that depict both Pukey and Uncle Rhabdo as clowns.


Symptoms of Rhabdomyolysis


Beyond muscle soreness, pain and stiffness, the condition may not cause many noticeable symptoms. Other symptoms of rhabdomyolysis may include general fatigue, muscle weakness, abnormal dark red or cola-colored urine and a marked decrease in the amount of urine the body produces.

If you suspect you may have rhabdo, see your doctor immediately. Only a physical exam and blood test can diagnose it, and early intervention is crucial for treatment of this potentially life-threatening condition. Treatment depends on the severity of kidney damage and may range from intravenous hydration and electrolyte replenishment to diuretics or kidney dialysis.


Expert Advice


There’s no telling whether you’ll fall prey to rhabdo, though male athletes tend to be more be susceptible than females. If you’re new to intense exercise or strength training, keep in mind that taking on a new or extreme program may be damaging to your body. Typically, programs like Crossfit, Insanity and P90X involve cookie-cutter workouts that aren’t made for everyone. Before beginning any fitness program, always assess your own fitness level. You may need to make necessary adjustments suitable for your body.

You can do your part to prevent rhabdo by taking some simple precautions. Make sure to maintain proper hydration and replenish electrolytes before, during and after intense workouts and in hot, humid weather. In high humidity, scale back or stay within your normal limits of intensity and resist sudden increases in exertion. When recovering from injury or illness, keep workouts light and slowly ease back into your previous intensity.

Trust me: Working out to the point of vomiting or injury is never okay and will only set you back further from your fitness goals.


Brian Maher is a personal trainer in Center City Philadelphia who specializes in weight loss and nutritional counseling. He is the owner of Philly Personal Training, a company offering convenient in-home personal training packages to busy individuals looking to improve their fitness levels. To learn more about Brian and his services, visit Read all of Brian’s posts for Be Well Philly here.

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