5 Workout Red Flags You Shouldn’t Ignore

Jessica Smith
by Jessica Smith
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5 Workout Red Flags You Shouldn’t Ignore

Profuse sweating, labored breathing, sore, burning muscles — all of these can signal a good workout. Yet there are some signs that your body can provide during exercise that you need to monitor so you work at the level that’s appropriate — and challenging enough — for your fitness level without risking an injury.

The truth is, overdoing a workout can be downright dangerous, so while some trainers may encourage you to “push till you puke or pass out,” we advise being more cautious. There are, in fact, several annual cases of exercise-induced rhabdomyolysis (also known as ER) that, while rare, can cause life-threatening side effects. According to the IDEA Health and Fitness Association, ER is typically brought on by an “unusual exercise load” or an “abrupt transition to a much greater exercise load,” and symptoms can include muscle pain, weakness, tenderness, fever and vomiting.

Of course, a lot of this seems like common sense: listen to your body, don’t overdo it, etc. But as a personal trainer, I’m constantly amazed at how many gym-goers suffer through because they think their workouts are supposed to make them feel sick or awful to get great results. That’s just not true! A good workout can be challenging, but a properly designed, progressive workout plan should be building your body up, not breaking it down.

Here are five red flags important to pay attention to during your workouts:


While the exact cause can vary by individual, muscle cramps can often signal dehydration, heat stroke or intensity overload. Pay attention to the degree of the cramp as well as the duration to figure out your best method of dealing with it. Is it minor enough that you can keep moving, or does it stop you in your tracks? Does it go away after a few minutes or linger throughout your session? A cramp that just won’t quit or doesn’t subside after a brief cooling-off period and proper hydration shouldn’t be ignored. This is probably your muscles crying out for help because you’re trying to do too much, too quickly.


Side stitches are a common form of muscle cramps that typically occur while running (though they can show up during other cardio exercise, too). They can often be prevented and/or reduced with a proper warmup, good posture and electrolyte balancing before and during your workouts. Side stitches are also known to subside as your fitness level builds, so the good news is that you’ll probably experience them less as you develop more endurance and stamina. However, if your stitch continues up your left shoulder, take it very seriously, as it could signal a heart attack.



Whether you’re trying to squeeze out those last few reps of heavy lifting, or you’re on your hundredth plié pulse in barre class, shaky muscles are a common occurrence during a tough workout. If the quivering is mild enough that you can power through and finish the set with good form, it can be a sign that you’ve reached the point of fatigue that can bring additional strength and endurance gains.

On the other hand, if your muscles are shaking so badly that it’s impossible for you to control your movements and/or maintain proper alignment during the exercise, then the risk outweighs the benefits, and it’s time to take a break until the rumbling subsides. And if you are shaking at the start of a session or without great exertion, there may be other factors behind the shaking, such as low blood sugar levels and dehydration.


This symptom can be brought on by a myriad of causes: dehydration, heat stroke or low blood sugar can cause feelings of dizziness or lightheadedness, as can standing up too quickly or changing various body positions while lifting weights. This doesn’t mean you should just shrug it off when it happens, especially if it happens regularly. When should you be concerned? If you’re otherwise healthy and well-fueled, dizziness that can’t be explained, doesn’t subside right away and/or that occurs often should be addressed by a medical professional.


Some people may feel nauseated if they exercise on an empty stomach while others may feel queasy when exercising too soon after eating, making this another point that should be monitored on a personal basis to find out what works best. If you know your stomach upset isn’t a result of what you ate (or didn’t eat), it may be your body’s way of asking you to dial down the intensity.

One final caveat: Everybody is different, and the information provided here should not be interpreted as medical advice. Please be sure to pay attention to your body’s signals, and seek proper medical attention immediately when and if appropriate.

Need some help finding a plan that’s designed to help you get results (and even enjoy exercise) with a balanced mix of workout styles and intensities? Don’t miss my top-rated, progressive home-workout program, the Walk STRONG: 6 Week Total Transformation System. MyFitnessPal readers save 20% when you use the exclusive MyFitnessPal promo code “3Z74EZAT” at checkout on Amazon.com.

About the Author

Jessica Smith
Jessica Smith

As someone who struggled to lose weight for years, Jessica found that the key to her own 40-pound weight loss was making small, healthy lifestyle changes that led to big, lasting results. Now, as a certified wellcoach, fitness instructor and personal trainer, she has spent the last 15 years helping students and clients reach their goals in New York City, Los Angeles and Miami. She now reaches millions online through her YouTube Channel and home exercise DVD series. Please visit walkonwalkstrong.com to learn more about her fun, results-driven programs for all levels of exercisers.


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