What is muscle fatigue: tips to sprint into sports season

 

If you want to get the most out of your training, the right breaks are also crucial. With the large sporting events back in full swing this year and outdoor sports on the rise, we should explain why performance is always best paired with rest and recovery. Discover what post-workout regeneration means for you and why it is so important.

When it comes to getting fit or staying fit, you probably first think of strenuous and relentless training sessions. And of course you can’t expect results without the hard work! But regeneration – that is, consciously taking breaks from training – is just as important as training itself. This applies to all sports and to every performance level, from beginners to Olympic athletes.

Proper regeneration not only boosts motivation and ensures a healthy training attitude, but it also promotes muscle growth and protects you from injuries. After all, during these rest phases, you give your body the opportunity to recover and repair itself and thus be prepared for the next intense workout session.

Read this article to learn how to support your training progress by taking some time out to avoid muscle fatigue. You will learn what the typical muscle fatigue causes are, how long regeneration phases should be and how you can further promote muscle fatigue recovery through sleep, nutrition and relaxation.

What does muscle fatigue feel like?

We need to distinguish between two kinds of muscle stiffness: pain during exercise – that is, direct or acute muscle soreness – and delayed onset muscle soreness (DOMS).

Acute and direct pain from muscle fatigue is the body’s direct reaction to exercise. Lactate (lactic acid) forms as a result of the strain, which momentarily results in your muscles being over-acidified. This is the pain you feel when you are in the final metres of a 100-metre sprint. Your muscles harden, the pain runs through your buttocks and leg muscles – but after a few minutes, you can no longer feel it and you can walk normally again. 

Delayed onset muscle soreness refers to the sore muscles that you feel about 12 to 72 hours after your workout. This type of muscle fatigue is caused by new, unfamiliar training stimuli – for example, when you increase the number of weights you bench-press, try new exercises, or extend your running distance. Sore muscles are often most intense three days after the training session. Symptoms of DOMS, which are triggered by microtrauma in the muscles, are as follows:^{[18, 19]}

• Pain
• Muscle stiffness
• Swelling of affected muscles
• Muscle fatigue
• Short-term muscle weakness

What are the main muscle fatigue causes?

The cause of muscle fatigue has been the subject of much debate in science. Two main hypotheses for muscle fatigue causes have emerged.

The first hypothesis is the classified as the metabolic hypothesis. It assumes that over-stimulating muscles results in intermediate metabolic products such as lactic acid, CO₂, phosphates or creatine.^[19] However, it has not been adequately proven in studies that lactic acid is the culprit behind muscle fatigue, which is why this explanation is being met with increasing scepticism.^[20]

Lactic acid or lactate is more likely to be responsible for the short-term muscle fatigue that occurs during exercise, for example on the last 15-metre stretch of a 100-metre sprint. Another explanation as to why metabolic products are not responsible for sore muscles is the half-life of lactate – the time it takes the body to break lactate down. The body requires about 20 minutes to break down the lactate produced during strenuous activity, yet much of muscle soreness usually only becomes noticeable one or two days after the workout.^[19]

The second hypothesis states that sore muscles are caused by microtrauma – that is, tiny injuries sustained in the sarcomeres, the muscle cells. This is also called the microtrauma hypothesis. Muscle fibres suffer this trauma from excessive mechanical stress with high and mostly unfamiliar exertion. The term ‘trauma’ in this context refers to the tiny cracks in the muscle fibre structures that have arisen as a result of high-intensity exercise.

Avoiding muscle fatigue: why is regeneration so important?

When you regenerate, many necessary processes take place in your body that can sustainably improve your later performance in sports.

If you do not take these breaks, you run the risk of overwhelming your body, which can lead to minor and major injuries and slow down your training progress. This is not only potentially unhealthy, but can also gnaw away at your motivation and thus further diminish your success so far.

Boost muscle growth and performance with regeneration

Training and exercise cause minute damage to your muscle tissue; these are called micro-injuries. When you exercise, your muscle fibres expand. This happens because your muscles want to adapt to external stimuli and recurring stress. The process by which the muscles expand or build up is called muscle protein synthesis.

Outwardly, you rest during your training break, but inwardly your body continues to work. Because while you are relaxing, this muscle damage is being repaired and renewed. Afterwards, the muscles are stronger than before so that they are best prepared for the next load. For this reason, you can increase your performance by exercising regularly and taking the right recovery breaks.

Studies have shown that muscle growth during regeneration is both faster and more effective – so you actually get stronger if you also take a break now and then.^{[1, 2]}

How does muscle regeneration reduce the risk of injury?

Not only will you improve your performance during exercise by letting your muscles regenerate, but you will also reduce the risk of injury.^[3] Because if you don’t give your muscles enough time to recover and rebuild, your muscles will still be worn out and fatigued the next time you train. This makes you more susceptible to injuries, such as muscle fibre tears or strains.^[4]

Can I lose weight during my recovery phase?

Especially in times of ample fitness apps and heart rate monitors that measure calorie consumption, many people who want to lose weight are tempted to burn as many calories as possible in a short time. But it is not advisable to forego training breaks and only look at short-term calorie consumption, especially as a beginner.

This is because regeneration helps you lose weight in the long term. Why? Muscle recovery makes the process of muscle growth far more effective. And when you build more muscle mass, you burn more fat, even when you’re resting. In addition, you gradually increase your performance levels when you work out, which makes your training sessions more intense – and thus also your calorie consumption.

What is the best way to promote muscle recovery?

The core of recovery is, of course, to avoid muscle fatigue by doing any sport for a certain period of time – let your body simply rest! But you can also pay attention to a few other things to help your body regenerate quicker. The most important tips are:

• Take a sufficiently long break (24 to 72 hours, depending on your training and fitness level)
• Get enough sleep
• Drink plenty of fluids
• Eat a meal with high-quality proteins and carbohydrates after your workout

Following these guidelines, which we go on to explain in more detail, can also reduce the recovery time you need between workouts. Sports scientists also recommend massages or fascia rolls, baths and relaxation – for example, through autogenic training or yoga.^[4]

Relaxation techniques are superb for additionally improving your cortisol levels – that is, your stress levels. Find out more about reducing signs of stress through relaxation and sports in our Health Portal article.

How many days rest do you need after working out?

How long you should rest from muscle fatigue depends mainly on your own fitness level and how hard the training session was. After a workout that was easy for you, a 24-hour break is often enough to regenerate and recuperate.

If the workout was very strenuous, it is better to take a break of 48 to 72 hours between two training sessions – sometimes even longer. You can often tell by how your body feels: if you are exhausted and have sore muscles, it is probably not time for another strenuous fitness session.^[2]

What is active regeneration?

Active regeneration is when you relax the right muscle groups that are experiencing muscle fatigue on a given day. If you are very active and fit, you can exercise every day. A skilfully put-together training schedule also allows you to exercise more often and at the same time actively rest your muscles.

A good rule of thumb is not to train the same muscle groups on two days in a row. For example, you can go running or cycling the day after you work out your upper body, as this mainly works your leg muscles. However, make sure to do light workouts on these days.

Does sleep promote recovery from muscle fatigue?

Sleep is a highly underestimated tool when it comes to muscle fatigue recovery. A restful sleep when you are recovering from a workout is one of the best things you can do for your athletic performance!

While you sleep, your body is still active: many processes continue while you sleep, including muscle reparation and energy regeneration. Especially after strength training, a relaxed night’s sleep is enormously important. If you don’t receive enough sleep, the repair processes taking place in your muscles can be disrupted. This can lead to minor muscle injuries not healing properly after training. And even muscle loss becomes more likely if you sleep too little.^[5]

Need help getting to sleep? Our sleep improvement supplements boost your ability to enjoy a great night’s sleep. Many of them contain the natural sleep hormone melatonin and the mineral zinc, which both boost relaxation as you drift off to sleep.

How can I recover from exercise through liquid intake?

During your recovery phases, it is important that you supply your body with sufficient water, because you most likely lost a lot of fluid through sweating. As always, it is best to simply drink tap or mineral water!

Isotonic or electrolyte drinks are also possible, but make sure that the drinks do not contain too much sugar. A drink should not have more than eight per cent carbohydrates. Otherwise, your body can only absorb the liquid slowly.^{[6, 7]}

Tip: Make your own isotonic drink easily! Mix two parts sodium-rich water and one part juice – for example, apple juice.

Why is sport nutrition important? 

The right nutrition is also part of regeneration after sport. Due to the micro-injuries sustained during training, the sugar glycogen is also broken down in the muscles and protein is partially broken down and destroyed. With the right food after sport, you help your body regenerate muscles quickly.

What foods help with muscle fatigue?

Among other things, it is important that you eat protein-rich foods, so your body can absorb the amino acids it needs to rebuild lost proteins. This supports regeneration and also your performance in the next training session. But glycogen also needs to be replenished in the muscles. So, carbohydrates are also important for gifting you new energy. Fats are not absolutely necessary after training and should not make up the main part of the meal. However, they do not do any harm in moderation, especially if they are healthy unsaturated fatty acids.^{[8, 9]}

Sports scientists recommend eating a meal with protein and high-quality, fibre-rich carbohydrates within 45 minutes and at the latest two hours after training.^[10]

Do antioxidants improve recovery?

While there is still a lot of research to be done on the topic, it is generally believed that foods rich in antioxidants can help with muscle fatigue. Antioxidants bind and fight harmful free radicals that are released by intense exercise. Due to their anti-inflammatory effect, antioxidants could have a positive effect on the muscle inflammation caused by exercise.^{[21, 22, 23]}

Foods that contain a lot of antioxidants are:^{[24, 25, 26, 27]}

• Cherry juice
• Pineapples
• Ginger
• Berries
• Dark chocolate
• Kale

In addition to these foods, the spice turmeric also has a particularly anti-inflammatory and pro-regeneration effect and is said to relieve muscle soreness.^[28]

Does omega 3 help muscle growth?

Omega 3 can also boost the muscle regeneration process.^[29] They also have an antioxidant effect. ^[30] Particularly reliable sources of unsaturated omega-3 fatty acids include:^[31]

• Freshwater fish (for example, salmon)
• Linseed oil
• Chia seeds
• Walnuts
• Fish oil and algae oil extracts

If you’re unsure whether or not your omega-3 levels are optimal, you can check them with an omega-3 test – at home or at your doctor’s. This type of test measures the omega-3 index in your blood as well as the ratio of omega 3 to omega 6. This ratio is crucial, as it plays a decisive role in your overall health.

Unsaturated fatty acids serve other important purposes in the body and have a major impact on your health. You can find out more about the benefits of omega 3 and 6 in our Health Portal.

Should I take amino acids on rest days?

Amino acids are the basic building blocks of proteins. Their most important tasks  include ensuring muscle structure and mobility. It is therefore important to provide your body with the right tools it needs to help rebuild muscles.^[32]

Your essential amino acid intake should increase when you do a lot of intense exercise, which is why you should make sure that you provide your body with the right protein sources – of the correct quality.^[33]

Did you know that watermelon is a hydrating source of amino acids. It contains a lot of the amino acid L-citrulline, which, according to  studies, decreases the amount of time it takes for people to recover from muscle fatigue.^{[34, 35]}

A term that is often associated with exercise and amino acids is branch-chained amino acids (BCAA), which refers to the three essential amino acids leucine, isoleucine and valine. They support muscle strength and endurance and counteract muscle atrophy.^{[36, 37]} BCAA can be bought as a supplement, but they are also found in many foods, for example in:

• Eggs
• Raw salmon
• Walnuts
• Rice

Not sure about your amino acid levels? A simple solution would be to have your amino acid levels tested. With an amino acid test, you can check the concentration of amino acids in your blood by collecting a blood sample – either at home or at your doctor’s. 

Last but not least: eat a balanced diet

A generally balanced diet is also crucial. This means, above all, eat plenty of fruit and vegetables and thus fibre, avoid highly processed ready-made products, replace white flour products with whole grains and make sure you do not develop any nutrient deficiencies.

What supplements help with muscle fatigue?

Many athletes swear by certain dietary supplements to support regeneration after workouts. Protein powders with essential amino acids and BCAA supplements are popular. The BCAAs can apparently activate enzymes that promote muscle growth, among other things. BCAAs are also involved in the regulation of blood sugar and are said to help counteract exhaustion during exercise and muscle fatigue.^[11]

For most people, eating protein-rich foods during the recovery phase is good enough. Dietary supplements for athletes with amino acids or BCAAs can be worthwhile if you do very intensive sports or have a low-calorie diet, are on a vegan diet or vegetarian diet and do not manage to get enough protein in your diet.

Supplements with essential amino acids are generally seen as a practical way to take in plenty of protein without adding too many calories.^[12]

How do I promote muscle fatigue recovery: relaxation & massages

Targeted relaxation helps you to calm down during your rest days. You can achieve this with meditation, yoga or autogenic training, for example.

According to a study, massages after exercise can significantly reduce muscle fatigue and pain caused by exercise.^[13] But professional massages are obviously not something most people can afford after every training session. As an alternative, some researchers suggest using fascia rollers on muscle groups during recovery. These rollers can be used to loosen fascia and tense muscles.

Fascia are connective tissues that run like a network through the entire body. Among other things, they cover your organs, bones, joints, and muscles. They help your body transfer strength, give it stability, protect the internal organs, and transport nutrients.

In studies, using fascia rollers has also been shown to reduce muscle soreness and weakness after training and could thus have a positive effect on your athletic performance in the long run.^[14] Fascia rolls are made of rigid foam and help to loosen the bonded fascia and break down collagen – and thus relieve pain.^[38] By massaging your fascia with this firm roller, you can loosen adhesions – the rolling motion pushes lymph fluid through the fascia and thus loosens congestion, which allows nutrients to reach the muscles more easily.^[39]

What should I avoid during recovery?

On the one hand, you should, of course, avoid overtaxing your body with too many closely timed training sessions. But alcohol and tobacco can also have a negative effect.

According to studies, alcohol after exercise can disrupt protein synthesis in the muscles and thus partially nullify the effects of your workout session.^[15] Smoking cigarettes also has a negative impact on muscles and bones and can reduce athletic performance and endurance, especially in the long term.^{[16, 17]}

Muscle fatigue & recovery – at a glance

Why is regeneration important for muscle fatigue?

During regeneration, many important processes take place in the body that, among other things, ensure muscle growth. If you give yourself sufficient time to rest after sport sessions, you will increase your performance and reduce the risk of injury.

How many days rest do you need after working out?

As a rule, you should take a recovery break of 24 to 72 hours after exercise – depending on how fit you are and how intense the training session was.

If you exercise regularly, you can also work different muscle groups on consecutive days. For example, on the day after jogging, your legs can regenerate while you train your upper body.

What is the best way to promote muscle fatigue recovery?

The three most important factors for fast and healthy regeneration are drinking plenty of fluids, getting enough sleep and eating protein and carbohydrate-rich foods after training.

In addition, you can support regeneration with targeted relaxation and massages or fascia rolls and boosting your nutrient intake through supplements.

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