Extreme Fatigue After Exercise? Here’s What Your Body’s Trying to Tell You

If you feel mild fatigue after exercise — on top of being sweaty and a bit sore — it’s okay, especially if you’re new to exercise. But there’s a limit. If you feel completely exhausted after a workout, it could be a sign of a health problem or a clue that you overdid it.

“It is normal to feel a bit winded, slightly tired, or even mildly sore after, depending on the nature of the workout,” says Tim Bish, a personal trainer and certified Men’s Wisdom Work coach in New York City. “But these symptoms shouldn’t feel overwhelming or unmanageable.”

Typically “normal” fatigue should last a few hours or overnight. But a good night’s sleep should let your body and brain bounce back, Bish says. Steps like drinking water, eating, stretching, and taking a hot shower or bath should also help, he says.

“Excessive fatigue will often not respond to these tactics and should be monitored carefully,” Bish says. If you feel like you’re not recovering well, or you’re more sleepy than usual post-workout, here’s what might be going on. Plus, find out how to avoid feeling fatigue after a workout in the future.

Some signs of extreme fatigue after a workout are:

• Weakness
• Nausea
• Headaches
• Recurrent or persistent injuries, such as stress fractures, muscle sprains, stress, and chronic joint pain
• Decline in performance
• Unusual pain, especially if it’s sharp or in areas that you didn’t train
• Trouble doing activities of daily living, including walking up stairs or standing up from a chair
• Inability to maintain alertness for important tasks, such as driving

1. You’re Pushing Too Hard

Pushing beyond your capabilities during your workout can leave you feeling completely gassed. It can add days to your recovery time, too.

This can happen when intense exercise causes muscle-tissue breakdown beyond what the body can handle. However, the condition isn’t all that common among most regular exercisers. It does occur in more advanced athletes like marathoners, bodybuilders, and CrossFitters.

If you feel weak and nauseous after your workout, or you have dark-colored urine, you might have rhabdomyolysis. Other symptoms include joint pain, muscle fatigue in your legs or other body parts, and weakness.

Treatment includes being put on fluids to flush your liver. If your condition is really extreme or left undiagnosed for too long, you may also need to be treated for kidney failure.

It’s important to get medical care right away if you think you may have rhabdomyolysis.

Fix It

If you’re very fatigued from pushing too hard in the gym, increase your workout intensity and length slowly over time. And stick to low-impact workouts when you're sore, says Erin Nitschke, a certified personal trainer and therapeutic exercise specialist in Cheyenne, Wyoming.

“There’s no one-size-fits-all approach when it comes to workout programming [or recovery],” she says. “The biggest key to success is starting slowly and choosing activities that are enjoyable and fulfilling.”

As a general rule, it’s best to do moderate-intensity exercise on most days of the week, says Kush Patel, MD, a sports-medicine doctor at Inova Sports Medicine in Sterling, Virginia.

2. You’re Doing Too Much

Overtraining is when you have exercised more than you have given yourself time to recover. “Overreaching” is basically a short-term version of overtraining. Both issues come from too much exercise and not enough rest. However, overtraining happens over the course of a month or more, while overreaching may occur after a single, intense workout.

What are the symptoms of over-exercising? If you have either problem, you’ll notice you’re constantly fatigued and sore. Your mental health is affected by overtraining and overreaching, too. Your sleep can be disrupted, you may get symptoms of depression, or you might experience the absence of menstruation (amenorrhea).

Fix It

Nitschke recommends fitting in at least one full rest day between vigorous workouts. A general rule of thumb is to rest a muscle group for at least 24 to 48 hours after training it.

3. You’re Not Hydrating Enough

Exercising makes you sweat. If you’re not prepared for your workout and you lose too much fluid, you can become dehydrated.

Heat complicates dehydration. Your body uses sweat to cool off, so exercising in a hot environment can make you lose fluids faster. If you’re going to work out somewhere very warm, make sure to hydrate more than you usually would.

Fix It

Hydrate before, during, and after a workout, even if you don’t necessarily feel thirsty. Aim to drink about 17 to 20 ounces (oz) of fluid a couple of hours before your workout.

4. You’re Not Fueling Properly

“This is when blood glucose levels drop too low to support the energy demands of a person’s body. The condition can affect people with and without diabetes,” Dr. Patel says. “When you exercise, your muscles need more sugar to supply energy.”

Your body uses sugar (glucose) that has traveled through your bloodstream and into cells for immediate energy. Your body can also store glucose in your muscles (called glycogen) for future use.

Fix It

In general, eating enough calories will give you the energy you need to get through workouts and the fuel your muscles need to recover. Nitschke recommends eating an overall well-balanced diet that includes lean proteins, healthy fats, complex carbohydrates, and enough calories.

When to Talk With a Doctor for Extreme Fatigue After Exercise

If you think you might be overdoing it, that’s a red flag. Listen to your body, and if you’re uncertain whether you’re over-exercising, talk with a trainer. They can give you personalized advice about how to tailor your workout intensity, length, and frequency.

If you notice that you’re regularly feeling exhausted after workouts and the next day, keep a symptom log to share with your doctor. Bish suggests seeking professional help immediately if you have:

• Trouble breathing
• Recurring pain or discomfort
• Headaches
• Confusion
• Nausea or vomiting
• Heart palpitations
• Tingling
• Sustained pain
• Fatigue that’s overwhelming or unmanageable

“Your doctor should always be a collaborator in your fitness regimen. Working out should ultimately make us feel stronger, more pliable, and more energized,” Bish says.

The Takeaway

• Trust your instincts. Only you can determine how severe your fatigue is.
• If something doesn’t feel right, speak with your doctor. They can help you identify any underlying condition that may be impairing your ability to exercise and create a safe workout plan for you.
• Balance your exercise plan with days off for rest.
• Eat a nutrient-rich diet.