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

  • By Performance Lab
  • 12 minute read
Feeling Tired After Workout Why It Happens and How to Fix It

It's normal for your muscles to feel fatigued after a workout. Whether you are working out for weight gain, burning calories, training, fat loss, you name it!

But for some, this tiredness extends to feeling sleepy, feeling exhausted, and even needing a nap. If you've ever asked, "Why do I feel tired after my workout? And what can I do about it?" This article has the answers you need.

In this article, we're digging into why you feel tired after a workout. We also share insight on how to fight feelings of extreme fatigue post-workout, including tips on lifestyle, sleep habits, and dietary supplements that can help you maintain your energy naturally. Let's get to it!

Quick summary:

  • Getting tired after a workout is a common challenge that can diminish the rest of your day and leave you feeling discouraged about regular exercise

  • Post-workout fatigue in healthy adults has many causes, including glycogen depletion, poor sleep habits, insufficient nutrition, high body temperature, low electrolytes, overtraining and other factors.

  • In this article we share tips on how to address the most common causes of post-workout fatigue naturally

  • We conclude this article with supplements that can help maintain your energy after exercise, including Pre Lab Pro, Performance Lab Caffeine 2, Performance Lab Energy, Performance Lab Mind and Performance Lab Sleep.

How to Fix the Thought "Why am I so Tired After Working Out"

Following 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

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)

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 recovery. Stay hydrated and refuel wisely to optimize your post-workout muscle glycogen stores and keep your energy levels soaring.

Brain Chemicals

Post-exercise fatigue involves a complex interplay of brain chemicals (neurotransmitters) that influence our mood and energy levels. 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 and limiting muscles ability to perform. As endorphins effects wear off, we may experience a post-exercise crash. Cortisol, a stress hormone, can also play a role in fatigue when its levels are elevated due to intense exercise.

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).

Overtraining Syndrome (OTS)

a photo of a bodybuilder in a gym who has crashed and is lying on the ground due to training too hard

If you're continually engaged in high intensity workouts in your exercise routine without sufficient rest, you risk overtraining, which can worsen fatigue and make you tired after exercise.

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)

The solution to OTS-induced fatigue: First and foremost, get more rest! Also design a fitness regimen that scales back a little, into the realm of low intensity exercise, and gradually increase up to moderate intensity, and so on, until you find the right balance of intensity during your exercise and energy afterwards.

You're Not Getting Enough Sleep

Sleep deprivation before training day almost guarantees you feel exhausted after working out. When it comes to exercise and sports, failure to get enough sleep can also lead to:(6)

  • Reduced accuracy

  • Higher risk of injury

  • Slower reaction time

  • Faster exhaustion (decreased time to exhaustion)

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 if you haven't slept enough.

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. Tart cherry extract can help because it:

  • Supplies inflammation-soothing activity that comforts sore muscles and joints post-workout. This is key because aches and pains can interfere with restful sleep.(7)

  • Supplies natural melatonin, the sleep hormone that signals for your body to feel fatigued when your ready for it -- at night, winding down in bed!(8)

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    image of Performance Lab® capsules

You're Dehydrated

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.

Ideally, you should consume between 2-3L of water per day. 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.

You've depleted your electrolytes

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.

If you're 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 have the energy to perform—and you're going to feel tired.

You want to fuel up your workout with protein, carbs, and a bit of healthy fats to sustain blood sugar and provide sufficient energy to power through training. Avoid processed or refined foods, as they tend to spike blood sugar and cause a significant crash afterward, resulting in fatigue.

It's also important to note that underlying medical conditions can also 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.

Your Cells' Mitochondria are Fried

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 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 rest, we can minimize fatigue and facilitate post-workout recovery.

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 Post-Workout Fatigue

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 keep you feeling energized after you train.

Pre Lab Pro®

Pre Lab Pro powder can also be a post work out remedy

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:

  • RedNite® Beetroot Powder—Helps boost energy levels and athletic performance by increasing circulation naturally

  • Setria® Performance Blend—The best for fighting muscle fatigue. Raises nitric oxide levels for greater in-gym performance, while also promoting growth and recovery.

  • Natural caffeine + Suntheanine®—Moderately dosed caffeine for energy with L-Theanine that helps take away the jitters and side effects. Perfect for working out and getting on with your day.

  • Ajipure® L-Tyrosine—Helps the body make brain chemicals that are depleted by exercise, but required for vitality and healthy performance after you train

  • NutriGenesis® Vitamins & Minerals—Premium cultured nutrients that you need most 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 so smartly designed that it sparks and sustains your energy, for your workout and the rest of your day.

Get the best price on Pre Lab Pro® here

Performance Lab® Caffeine 2

Performance Lab Caffeine for central and peripheral fatigue

Caffeine can be helpful for exercise fatigue -- as long as you use it responsibly. Performance Lab® Caffeine 2 is a new take on caffeine that helps you do just that, delivering 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 Suntheanine® L-Theanine

  • 250 mg Ajipure® L-Tyrosine

  • NutriGenesis® Caffeine Balance B-Complex

    • 500mcg Riboflavin

    • 50mcg Vitamin B6

    • 167mcg Folate

    • 2mcg Vitamin B12

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

The result? A cleaner, healthier, more relaxed energy with no side effects. It's perfect for perking you up after an exhausting training session at the gym, or even as part of your daily routine.

Get the best price on Performance Lab® Caffeine 2 here

Performance Lab® Energy

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), 750 mg

  • BioPerine® Black Pepper Extract, 2.5 mg

  • Bio-Enhanced® R-Lipoic Acid, 150 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.

Get the best price on Performance Lab® Energy here

Performance Lab® Mind

Performance Lab Mind

Do you feel physically and mentally exhausted after you work out? Performance Lab® Mind is a brain supplement that might be perfect for you. It has a special design that helps with mental recovery after exertion, while also boosting cognitive performance and nourishing brain health over time. It supplies:

  • Cognizin® Citicoline, 250 mg

  • Sharp-PS® Green (Phosphatidylserine), 100 mg

  • Ajipure® L-Tyrosine, 250 mg

  • Maritime Pine Bark Extract (95% proanthocyanidins), 75 mg

This formula supplies the L-Tyrosine that promotes brain chemicals that help you stay energized post-workout. Its Citicoline is notable as well because it has been clinically shown to increase brain energy metabolism by almost 14%.

Get the Best Performance Lab® Mind Deal Now

Performance Lab® Sleep

Performance Lab Sleep

If you want a direct way to feel more energized after exercise, optimize your slumber with 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

  • TryptoPure™ L-Tryptophan, 250 mg

  • Magnesium Complex: NutriGenesis® Magnesium, Magnesium Bisglycinate, Magnesium Taurate, 100 mg

Combining these three ingredients delivers all of the individual and synergistic combo benefits of today's most advanced sleep supplements. It helps gently relax your nervous system, unwinding tense muscles and reducing spasms.

The result? You wake up in the morning rejuvenated, clear-headed and primed to perform. With sleep this deep, you can stay energized the whole day through... even if you engage in high intensity exercise.

Get the Best Performance Lab® Sleep Deal Now 


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 lifestyle changes, fitness routine adjustments and nutritional supplements that help restore your energy for good.

There are plenty of additional options for accelerating recovery time and rejuvenating vitality after exercising—massage, foam rolling, cryotherapy, contrast showers, and more. And while implementing active recovery techniques is essential to support muscle recovery, what's in your supplement regimen can also help facilitate healing and reduce fatigue.


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