Feeling Tired and Sleepy After Workout: Why It Happens and How to Fix It

There's no two ways about it - you'll never regret getting your daily exercise done.

It's such a good feeling.

Even when your muscles are shaking, your legs are aching, and your body feels exhausted—you know that in order to get the results you want, your body will need to be pushed to new limits.

Whether you're there for weight loss, inch loss, weight gain, or smashing a personal best—these aches and exhaustion, well this is body's natural response to intense activity. Right?

But for some, this tiredness extends to feeling sleepy, exhausted, and even needing a nap.

If you’ve ever asked, “Why do I feel so tired after my workout?” This article has the answers you need.

Here, we’re digging into why you feel tired after a workout, and what you can do about it.

We share insight on common culprits and how to fight feelings of extreme fatigue post-workout, including tips on lifestyle, sleep habits, and dietary supplements that can help you maintain sustained energy naturally.

Let’s get to it!

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"Why Am I So Tired After Working Out - and How to Fix It?"

Here are some of the top causes of why exercise leaves you feeling tired, along with practical insight on how to address these causes naturally.

Glycogen Depletion & Muscle Recovery

Glycogen is the body's primary fuel source. It is stored in the body's muscles and liver. Active muscle tissue burns through glycogen stores at a relatively quick rate, especially during high-intensity, strenuous exercise. Low muscle glycogen levels are linked to diminished performance and exercise-induced fatigue. [1]

How to replenish muscle glycogen after a challenging training session

Restoring glycogen via diet refuels your body and fights fatigue. Aim for eating a mix of both simple and complex carbohydrates to ensure a steady release of energy. Foods like bananas, sweet potatoes, whole grains, and fruits are excellent choices as a post workout snack. Timing is crucial, so try to eat these carbohydrates within 30 minutes to two hours after exercise when your muscles are most receptive to glycogen uptake. [2]

Additionally, pairing carbohydrates with a source of protein can further enhance glycogen replenishment and aid in muscle repair. [13] Stay hydrated and refuel wisely to optimize your post-workout muscle glycogen stores, keep your energy levels high, and help repair muscle tissue.

Brain Chemicals, Mental Health, and Exercise Fatigue

Post-exercise fatigue involves a complex interplay of brain chemicals (neurotransmitters) that influence our mood and energy levels, which can affect your mental health and motivation. [14] Researchers have suggested that serotonin and dopamine, and specifically the ratio between them, may play a role in exercise-induced fatigue: [3]

• Serotonin is linked to "hitting the wall" during exercise;

• Dopamine is associated with improved exercise performance.

Additionally, endorphins, the brain's natural painkillers, are released during exercise, producing a temporary high. [15] As endorphins effects wear off and other neurochemical and CNS changes take place, we may experience a post-exercise slump. [16, 17] Cortisol, a stress hormone, can also play a role in fatigue when its levels are elevated due to intense exercise. [18, 19]

To maintain brain chemicals and fight fatigue: Understanding these brain chemical factors helps us address post-workout tiredness and find effective strategies for recovery and energy restoration.

To help your body make new energy-related brain chemicals after working out, consider supplementing with L-Tyrosine . An amino acid, L-Tyrosine is popular among athletes as a sports nutrient for many reasons, including its key role as a "building block" of brain chemicals such as dopamine. [4]

To counter the cortisol that makes you crash, consider an adaptogen herb like Rhodiola rosea. Used for centuries to help physical performance, including by Russian Olympic athletes, Rhodiola rosea works in part by blunting the body's release of cortisol under stress (such as intense training). [20]

Overtraining Syndrome (OTS) & Your Fitness Regimen

If you’re continually engaged in tough workouts in your exercise routine without sufficient rest, you risk overtraining and potentially developing exercise fatigue syndrome, which can worsen fatigue and make you tired after exercise. [21]

Overtraining syndrome (OTS) can result when overreaching is taken to the extreme and combined with an additional stressor. OTS results from systemic inflammation and its subsequent effects on the central nervous system, such as mood changes, central fatigue, and neurohormonal changes. [5]

Insufficient Sleep

Sleep deprivation before training day can make you feel exhausted after working out, and insufficient sleep over time compounds that fatigue. [23] When it comes to exercise and sports, failure to get quality nighttime sleep can also lead to [6]:

• Reduced accuracy
• Higher risk of injury
• Slower reaction time
• Faster exhaustion (decreased time to exhaustion)
• Sleep inertia
• Poor morning workout efficiency

While you may feel energized during your workout thanks to the rush of endorphins and hormones, you're likely to feel a surge of fatigue after the high wears off.

Elite athletes sleep tip: Consider taking tart cherry extract. There are a million basic sleep tips out there, but this one is next level if you've got post-workout fatigue and want to support a healthy, consistent sleep cycle. Tart cherry extract can help because it:

• Supplies inflammation-soothing activity that comforts sore muscles and joints after an intense workout. This is key because aches and pains can interfere with good night's rest. [7]
• Supplies a gentle dose of natural melatonin, a hormone that raises at night and helps signal to the body it's time to fall asleep. It's more of a clock-setter than a direct sedative; working together with many sleep-promoting factors such as body temperature changes and the release of calming neurotransmitters like GABA and adenosine. [8]

Another tip is tracking how much sleep you're getting. For most people, 7-9 hours per night is the sweet spot.

Hydration, Physical Activity, and Athletic Performance

We all know how vital drinking water is. But do you drink water before, during, and after your workout?

If you're feeling ultra-tired after training, it could be because you're not adequately hydrated. Hydration is a critical piece of the workout puzzle. As we said, dehydration not only impairs cognitive function, but it also affects muscle contraction and recovery. [24, 25]

Ideally, you should consume between 2-3L of water per day. [26] Alternatively, divide your body weight (pounds) in half, and that's what you should be drinking in ounces per day. If you're sweating profusely or consuming caffeine, add an extra 20 ounces for each.

And during exercise, aim to drink 7-10 ounces of fluids every 10-20 minutes. But don't overdo it! Drinking too much water can lead to electrolyte loss, which we will cover next. [27]

Depleted Electrolytes Affecting Your Athletic Performance

A key part of healthy hydration is maintaining your electrolyte levels. Electrolytes are charged minerals -- including sodium, potassium, magnesium, and calcium -- that facilitate hydration and enable electrical signals to be carried through the body.

Sweating during exercise causes electrolyte loss. [9] If you don't replace electrolytes lost and levels get too low, you may experience symptoms like muscle cramps, fatigue and diminished workout performance. Consider sports drinks and coconut water as intra-workout fluids; both supply good levels of electrolytes.

A high-quality multivitamin can also deliver the charged minerals you need to restore what exercise takes away.

You're Not Fueling Your Body Properly

Proper nutrition will make or break your workout performance and muscle growth. Insufficient fuel can also be a significant cause of feeling tired post-workout. [28]

If you're consistently loading up on processed and refined foods (a donut as a pre-workout snack, for example) that are devoid of the nutrients your body needs to thrive, it's not going to deliver optimal energy to perform—and you're going to feel tired.

You want to fuel up with a well balanced diet of protein, carbs, and a bit of healthy fats to sustain blood sugar and provide sufficient energy to power through training. Avoid ultra-processed foods, as they tend to spike insulin and cause a crash afterward, potentially resulting in fatigue and low blood sugar.

It's also important to note that underlying medical conditions can cause post-workout fatigue. If you suspect something other than the three reasons we mentioned is causing your fatigue, talk to your doctor to run tests.

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Your Cells' Mitochondria are Affected Due to Muscle Fatigue

Mitochondria, the powerhouses of our cells, play a significant role in post-exercise fatigue. During exercise, our muscles require increased energy production, and mitochondria are responsible for generating that energy in the form of adenosine triphosphate (ATP). [10]

However, intense physical activity can lead to mitochondrial damage, muscle fiber strain, and oxidative stress.

This can result in reduced ATP production, and accumulation of metabolic byproducts that contribute to fatigue. Additionally, as part of the recovery process, mitochondria need to repair and regenerate, which can also contribute to post-exercise fatigue.

By supporting mitochondrial health through proper nutrition and adequate rest, we can minimize fatigue and help your body recover efficiently.

Some nutrients have also been shown to support mitochondria. CoQ10 and PQQ are two examples of energizing nutrients found in supplements that help to regenerate and optimize mitochondria. [11, 12]

One of our supplement recommendations, Performance Lab® Energy , supplies both these nutrients… but more on that below.

Best Supplements for Exercise Fatigue and Muscle Recovery

One of the easiest ways to fight tiredness after training is smart supplementation with the right nutrients. Following are some of the top products on the market today to help you feel energized after you train.

Pre Lab Pro®

You may already be taking this red-hot pre-workout. But if it's a pre-workout, how can it help you stay energized after you train? The answer lies in this formula's design, which provides a wide array of ingredients that can help maintain energy in body and mind before, during and after your session. It supplies:

• Red Beet Powder—Helps promote energy levels and athletic performance by increasing circulation naturally.
• Setria® Performance Blend—Addresses muscle fatigue. Raises nitric oxide levels for greater in-gym performance, while also promoting growth and recovery.
• Natural caffeine + L-Theanine—Moderately dosed caffeine for energy with L-Theanine that helps smoothen the jitters and side effects. Perfect for working out and getting on with your day.
• L-Tyrosine—Helps the body make brain chemicals that are depleted by exercise, contributing to vitality and healthy performance after you train.
• NutriGenesis® Vitamins & Minerals—Premium cultured nutrients that feed your body after vigorous activity, including iron and B-complex vitamins that play key roles in maintaining your energy.
• Himalayan Pink Salt—A great natural source of the electrolytes you need to stay hydrated and maintain strong athletic performance.

The take home message: Pre Lab Pro is designed to support smooth energy levels without the fatigue crash later. However, if you're struggling with fatigue due to overtraining or lack of sleep, you'll want to check our other options on the list.

Shop Pre Lab Pro®

Performance Lab® Caffeine 2™

Caffeine can be helpful for exercise fatigue -- as long as you use it responsibly. It's ideal for breaking through energy slumps and plateaus but should be avoided in cases of fatigue caused by overtraining; for this, the best solution is rest and recovery (the last product on this list is designed for this exact goal). 

Performance Lab® Caffeine 2™ is a new take on caffeine that delivers the stimulant at a low dose, combined with other nutrients that make it work even better. It supplies:

• 50 mg of Natural Caffeine from coffee beans
• 100 mg L-Theanine
• 250 mg L-Tyrosine
• NutriGenesis® Caffeine Balance B-Complex
  • 500mcg Riboflavin
  • 750mcg Vitamin B6
  • 170mcg Folate
  • 2mcg Vitamin B12

This formula smooths out caffeine jitters with L-Theanine and helps support dopamine and other brain chemicals depleted by training with L-Tyrosine. It also provides B-Vitamins that are crucial for both cell energy and brain chemicals.

The result? A cleaner, healthier, more relaxed energy with a minimal chance of side effects. It's perfect for perking you up after an exhausting training session at the gym, or even as strategic tool for energy-demanding days.

Shop Performance Lab® Caffeine 2™

Performance Lab® Energy

Maybe caffeine isn't your thing. Or maybe you took it before your workout, and don't want to use it again for energy. In cases like these, Performance Lab® Energy is a great stim-free option to consider.

Performance Lab® Energy is a caffeine-free energizer that primarily works by supporting cell energy processes, including optimizing the cell powerplants called mitochondria that you need for vitality before, during and after your workout. It supplies:

• MicroActive® Q10 ( CoQ10 ), 100 mg
• BioPQQ® ( Pyrroloquinoline Quinone, or PQQ), 10 mg
• Acetyl-L-Carnitine (ALCAR), 500 mg
• BioPerine® Black Pepper Extract, 2.5 mg
• Bio-Enhanced® R-Lipoic Acid, 100 mg

This is not your typical spike-and-crash energy pill or drink. Instead, it works by supporting energy production in practically every cell in your body. It's safe, natural and legal, and produces a revitalizing surge that feels clean and jitter-free. In other words, it's perfect for post-workout use.

Shop Performance Lab® Energy

Performance Lab® Sleep

If you want gentle support for your sleep and next-day energy, consider trying Performance Lab® Sleep. It features Montmorency tart cherry, which we've highlighted for its muscle- and joint-soothing activity and melatonin support. Overall, the formula includes:

• CherryPURE® Montmorency tart cherry, 500 mg
• L-Tryptophan, 200 mg
• Magnesium Complex: NutriGenesis® Magnesium, Magnesium Bisglycinate, Magnesium Taurate, 100 mg

Combining these three ingredients may support the nervous system for healthy, full-night's sleep and more energy during high intensity exercise the next day.

 Shop Performance Lab® Sleep

Conclusion: Good Night's Rest, Foam Rolling, and Napping After a Workout

Exercise fatigue is common, and the factors that cause it differ between people. For some, it may be overkill in the gym, while for others, it could be because of lifestyle factors. The good news is you can take matters in your own hands with healthy lifestyle changes (such as ensuring good night's sleep), strategic rest days, fitness routine adjustments, and nutritional supplements that help promote optimal energy for good.

There are plenty of additional options for promoting recovery time and rejuvenating vitality after exercising—massage, foam rolling, gentle stretching to promote blood flow, cryotherapy, contrast showers, or simply napping after a workout. And while implementing active recovery techniques is essential to support muscle recuperation and overall health, what's in your supplement regimen should also be considered when dealing with persistent fatigue. [29]