If you love working hard in the gym, chances are you’ve had your share of strains and pains. But have you ever imagined that your workout might land you with a $30,000 hospital bill? It’s hard to believe, but a quick Google search turns up story after story after story about an intense workout that led to hospitalization for exertional rhabdomyolysis, a condition that puts our kidneys at risk of severe damage.

Also called exercise-induced acute kidney injury, it happens when we really, really overdo it while exercising—like when a teen who was new to working out pushed himself through a 90-minute arm workout or when the Iowa football team’s training protocol went from “intense” to “insane.”

Normally, exercise causes tiny micro-tears in our muscles. Afterward, our body repairs them and we get stronger. The tearing releases a protein called myoglobin into our bloodstream, where it flows to the kidneys and is filtered into our urine. If we have too much micro-tearing at once, the amount of myoglobin that needs filtering can overwhelm and damage our kidneys.

This turns normal workout soreness into the stuff of nightmares. Rhabdomyolysis patients suffer through muscle pain, weakness and sometimes significant swelling in the damaged muscles. Then there’s the hospital stay—nine days, in one woman’s case—not to mention the hospital bill. After that, there’s at least a month of no exercise allowed before recovery can begin.

It’s scary stuff, not least because there aren’t obvious warning signs. It’s not always clear when someone has entered the danger zone, and the threshold for overdoing it is different for everyone. Thankfully, we can take steps to reduce our risk and improve our chances of being able to work hard over the long haul.

Tip #1: Learn to let enough be enough

The sense of power and confidence we get from pushing ourselves is amazing, but there’s a lot of wisdom in recognizing when our efforts have gone from being beneficial to being destructive. Whether our system is already too stressed to handle more strain or we’ve already done something formidable, we have to live to fight another day!

So how do we know when to say “enough”? Aside from our overall stress load (you can read more about it in this article), we need to pay attention to our level of control. When our muscles start to fatigue, it makes it harder to stay in control of our movement. For example, if you’re not very experienced with push-ups, you might only be able to do one or two before you start wiggling around and breaking form. Then you might switch to doing “negatives” such as starting in a plank position and slowly lowering down to the ground before sitting up and starting over. “Enough is enough” when you can no longer do even the negative movement with control. And honestly, if you’ve put in that much effort, you’ve already worked incredibly hard!

Tip #2: Rest while you work

We all know the importance of a recovery day or a good night’s sleep to our performance. But did you know rest is equally important during your workout? Personal trainers and lifting coaches have a secret weapon when it comes to getting maximum results with less risk—work/rest intervals. Basically, this refers to the amount of rest time between sets of an exercise or between circuits in a workout. It lets you recover from the set so you can go again.

The amount of rest depends on the type of exercise you’re doing. When weightlifting for power, strength or size, you might lift for 30 seconds, then spend the next one to five minutes resting. Lifting for muscular endurance uses lighter weights, with rest periods of 30 to 60 seconds. During cardio training—the kind that makes it hard to hold a conversation—it’s common to go hard for one minute, then rest for 30 seconds to a minute.

Tip #3: Water is everything

It’s hard to overstate the importance of hydration for preventing kidney issues. In fact, the treatment for rhabdomyolysis is supervised intravenous hydration (for days). Staying hydrated helps prevent not only rhabdo but also kidney stones. The little balls of agony form when you have super-concentrated urine, which happens when you’re dehydrated. Following the basic recommendation to drink when you’re thirsty is a good start, but the trick is to pick out the situations in which it hasn’t occurred to you that you might need to drink up—like at work or while traveling when it might be difficult to get to a toilet. And if you have a cold, you’re likely more dehydrated than normal.

Tip #4: Rethink aches and pains

This clinical resource recommends avoiding nonsteroidal anti-inflammatory drugs (NSAIDs) before vigorous exercise. This class of drugs includes ibuprofen, naproxen and others under brand names like Advil, Aleve and Motrin. They work to reduce inflammation (yay!) but can reduce blood flow to the kidneys during vigorous exercise (boo!). A safer bet is to skip the painkillers before your workout. Ice baths, taking a recovery day and even non-NSAID painkillers like acetaminophen (Tylenol) are better choices.

Tip #5: Value the less-intense efforts, too

Sometimes we can get caught up in a “harder is better” approach to exercise. But the truth is, our not-so-hard activity makes just as much of a contribution to our overall health and longevity. Compared to a sedentary lifestyle, light activity each week such as gardening, walking and moderate jogging can reduce our risk of developing kidney stones and reduce our risk of kidney cancer by a whopping 77 percent. These activities also tend to reduce stress and promote recovery from hard workouts.

Our kidneys are hardworking organs, but too much intense exercise can overwhelm them. To avoid a kidney injury, we need to listen to our bodies and pay attention to their signals. Having the wisdom to say “that was enough” will keep us in goal-crushing shape for years to come.

Photo credit: jacoblund, Thinkstock; Jacob Lund, Adobe Stock; nensuria, Thinkstock; jacoblund, Thinkstock; joanna wnuk, Thinkstock; Rob Bye, Unsplash