Have a hard time moving your muscles after an intense workout session? It could be muscle fatigue which one may experience in the form of low energy levels, muscle soreness, and weakness.
It is okay to feel tired after your training or gym session. But one must be able to recover quickly as staying fatigued for long can reduce athletic performance and increase injury risk.
This review mainly focuses on muscle fatigue, specifically during intense exercise, to give you a fundamental understanding and potential therapies to combat muscle fatigue.
What is muscle fatigue?
Fatigue is a common symptom and is associated with various health conditions. It can be acute or chronic, where one can quickly get relief from acute by making dietary or lifestyle modifications. However, chronic fatigue may last up to months and require medical treatment.
Muscle fatigue is defined as exercise-induced reduced muscle ability to exert a force or physical action. It makes us feel weak and exhausted and limits our ability to perform. The tiredness we feel after repeated movements during training or exercise is called fatigue.
Some muscle tiredness is mainly muscle fatigability when the muscle starts normally but exhausts very quickly and takes longer than usual to recover.
What is muscle weakness?
Muscle weakness refers to the inability of muscles to contract correctly due to a lack of strength. No matter how hard you try but there is a reduction in the force which muscles can exert.
Muscle function reflects overall health status, muscle quality, protein, and fat percentage in the body. In health, muscle fatigue is momentary, and recovery occurs rapidly.
However, inactivity, whether due to lifestyle choices, injury, or chronic disease, muscle fatigue may occur prematurely and persist, jeopardizing an individual’s safety because weakness can lead to falls and injuries.
What causes muscle fatigue & weakness?
Although exercise is one of the major causes of muscle fatigue, there could be other reasons.
- Age – We tend to lose muscle with increasing age, and this age-related weakness increases the risk of physical disabilities and falls.
- Anxiety – Anxiety causes our muscles to tense as our mind constantly scans the environment for threats causing physical and emotional distress.
- Chronic fatigue syndrome – During this syndrome, fatigue lasts for six months or more. It can affect memory and concentration and cause dizziness.
- Dehydration – Dehydration affects muscle performance by causing electrolyte imbalance, stiffness, swelling, and decreasing strength resulting in symptoms of DOMS (Delayed Onset Muscle Soreness).
- Depression – Depression not only affects us mentally, but it can also cause physical symptoms like fatigue, pain, upset stomach, and restlessness.
- Hypothyroidism – People with hypothyroidism are prone to muscle fatigue. Thyroxine deficiency affects energy metabolism, which results in the loss of fast-twitch muscle fibers causing muscle fatigue and slow muscle contraction.
- Sedentary lifestyle – To maintain muscle strength, staying active and using your muscles is essential. A sedentary lifestyle can weaken our muscles and reduce strength, causing fatigue.
- Lactic acid production – During intense workouts, muscles often get fatigued during lactic acid build-up in the muscles when oxygen levels are low.
- Sleep deprivation – Lack of sleep causes our body to release less insulin. It affects our energy levels and makes us feel tired throughout the day.
- Myositis – It means muscle inflammation that causes muscles to become painful, tired, and weak.
- Nutrient deficiency – Nutrients like calcium, potassium, vitamin D, magnesium, iron, and folic acid are essential for the optimal functioning of our muscles. A lack of nutrients can weaken our muscles, causing stiffness and fatigue.
- Pregnancy – Many hormonal changes occur during pregnancy, making us feel exhausted.
- Fibromyalgia – This condition causes muscle and joint pain throughout the body and results in symptoms like muscle fatigue, cramps, sleep issues, etc.
- Infections – Illnesses and infections can result in inflammation, resulting in muscle fatigue and tiredness. It is commonly observed during flu, hepatitis, tuberculosis, malaria, and dengue.
- Chronic Diseases – Chronic conditions like anaemia, cancers, diabetes, lung, kidney, or heart disease may affect our muscles’ blood supply of oxygen and nutrients. It can cause muscle pain or weakness as our muscles get tired quickly.
- Injury – Muscle injury can damage muscle fibers and cause swelling and inflammation. It can weaken the muscles and make them painful to use.
- Nerve Conditions – Some nerve conditions which can damage muscles are botulism, cervical spondylosis, multiple sclerosis, autoimmune disorders, and spinal cord injuries.
- Addison’s Disease – In this disease, our adrenal glands there is insufficient production of the steroid hormones like aldosterone and cortisol.
What causes muscle fatigue during exercise?
- Improper diet – Imbalanced diet and poor nutrition intake can significantly affect your energy levels and muscle recovery rate. Therefore, the diet must have a well-planned ratio of carbs, proteins, and fats with vitamins and minerals.
- Insufficient carbohydrate intake – If you are consuming a carb-restricted diet, there may be a possibility of not taking enough carbs to keep energy levels up during workouts resulting in the early onset of fatigue.
- No pre-workout meal – It is advisable to consume a pre-workout snack; however, the timing matters a lot. The meal should not be too close to the workout time as it might make you feel sluggish. Also, the gap between the last meal and workout should not be huge.
- Inadequate water intake – Dehydration decreases blood volume and affects the supply of nutrients and oxygen to your muscles. It also causes muscle cramps. Hence one must aim to stay fully hydrated to fight exercise-induced fatigue.
- No in-between rest while training – To maximize your athletic performance, it is vital to have a well-planned exercise regime with regular breaks to ensure proper recovery and prevent fatigue.
- Inadequate sleep – Ensure at least 7-8 hours of sleep per day. Our body produces growth hormones during sleep which is essential for muscle recovery. So if you have noticed your energy levels dropping during exercise, getting a few extra hours of shut-eye might be the key.
- Overtraining – Pushing yourself too hard or overtraining damages muscles. Workout intensity must be increased carefully to prevent unnecessary fatigue and muscle injury.
- Elevated stress levels – Workouts cause a lot of stress by increasing cortisol levels in the body. But if you are already stressed, it adds to the burden, thereby significantly affecting physical performance.
Factors affecting muscle contraction and fatigue
These factors can affect muscle contraction and contribute to the development of muscle fatigue.
- Brain Nerves – Some studies suggest that exercise induces changes in the concentrations of some neurotransmitters, and fatigue arises from changes within the Central Nervous System (CNS).
- Blood Flow and Oxygen Supply – One of the crucial roles of blood flow is to supply oxygen to the working muscles. During high-intensity workouts, the demand for more oxygen doesn’t get fulfilled, thus resulting in an imbalance of metabolic equilibrium and fatigue.
- Heat Shock Proteins (HSPs) – Fatigue reactants like HSPs and cortisol – stress hormone may also contribute to muscle fatigue. It has been observed that HSP25 is abundant in skeletal muscles, and their concentration increases with increased muscle contractile activity. A high level of HSP25 is associated with fatigue and localized pain.
How long does muscle fatigue last?
The duration you suffer from muscle fatigue will depend on how far you have pushed yourself. Though muscles usually recover within three to five days, one must start a workout after completely recovering if it lasts longer.
Muscle fatigue symptoms
- Muscle twitching
- Muscle cramps
- Localized pain
Muscle fatigue treatment
- Anti-inflammatory foods – Include foods like watermelon, ginger, tart cherry, and pineapple, which exert an anti-inflammatory effect.
- Hot or Cold pack – Consult a physiotherapist, and you can opt for a heat or ice pack as per the recommendation.
- Practice yoga – Simple yoga exercises promote stress relief, help stretch, and ease the tension.
- Sleep wiser – Not only sleep duration, but the sleeping position is also significant. Sometimes, incorrect sleep positions can cause back muscle pain. You can sleep by keeping a pillow between the legs. However, the best way is to sleep sideways by bending your knees towards your chest.
- Synthetic products – Caffeine, ephedrine, and pseudoephedrine are a few synthetic products that help combat muscle fatigue by acting as stimulants and reducing exhaustion. Some of them are not approved by NADA/WADA; therefore, one must be careful when opting for synthetic products.
- Natural products – Several natural products and herb extracts act as potent anti-fatigue agents. They enhance aerobic capacity, fight oxidative stress, provide endurance and enhance energy metabolism. Panax ginseng, garlic, Rhodiola rosea, and Ginkgo biloba are a few examples.
- Dietary supplements – Nutritional supplements are a popular means for performance enhancement. They are IOC (International Olympic Committee) approved. Some effective dietary supplements for reducing muscle fatigue are omega-3 fish oil, multivitamins, and glucosamine. In addition, athletes also use some sports supplements or ergogenic aids like creatine, L-carnitine, beta-alanine, and glutamine. They relieve muscle soreness and inflammation, amplify energy levels, and neutralize lactic acid accumulation.
Tips to avoid muscle fatigue while exercising
- Nutrition – Have a well-planned diet and divide all the macronutrients based on workout duration and intensity. The diet should also focus on antioxidants, vitamins, and minerals.
- Correct meal timings – Meal timings play a significant role in maintaining energy levels and post-workout recovery. For example, a combination of protein with carbs post-workout is recommended to repair damaged muscles, build new muscles and replenish glycogen stores.
- Hydration – Sufficient water intake throughout the day and sports drinks pre or during exercise are beneficial in preventing dehydration, electrolyte loss, and muscle fatigue.
- Improve endurance – A good aerobic capacity help reduce and delay fatigue. As endurance increases, the added oxygen boost in the blood enables muscles to work for extended periods and prevent lactic acid build-up. Make sure that your workout routine also involves improving endurance.
- Correct form of exercising – Muscle fatigue can also occur during a lack of coordination and incorrect movements during exercise. Hence it is necessary to focus on body mechanics and train using the right strength and flexibility.
- Rest – Allow adequate rest between workout sessions and strength repetitions. Take at least a day’s rest every week to let your muscles recuperate thoroughly.
Frequently Asked Questions (FAQs)
1. What is the main cause of muscle fatigue?
The most common cause of muscle fatigue is exercise and lactic acid accumulation. However, there could be several other underlying causes like nutritional deficiencies, no physical activity, ageing, medical conditions, etc.
2. How does fatigue affect muscle performance?
Muscle fatigue is experienced when the muscles cannot exert their power to full potential, and it tends to decline with every contraction. Clinical trials suggest that it happens due to the accumulation of carbon dioxide and a decrease in the oxygen levels in the body.
3. How do you prevent muscle fatigue?
Follow these simple tips to reduce or delay the onset of fatigue:
- Plan your workout schedule.
- Avoid overtraining.
- Consume diet as per the body’s needs and workout intensity.
- Stay hydrated.
- Eat fresh food.
- Get adequate sleep.
4. When to see a doctor during muscle fatigue?
It is advisable to seek medical advice if your muscle pain doesn’t subside with proper rest and you experience extreme muscle pain, fever, dizziness, difficulty breathing, and stiffness.
5. I have muscle weakness – what will the doctor do?
Apart from self-care, the doctor may prescribe you some medications, hot or ice packs, dietary supplements, compression bandages, etc.
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