To understand the causes of muscle fatigue, it is worth looking at what exactly muscle fatigue is. If you exercise regularly, you may be aware of feeling a dull ache in your muscles or feeling tired or lacking in energy that makes it difficult for you to complete your usual daily tasks. But it’s not just exercise that can cause muscle fatigue, there are many health conditions for which muscle fatigue is a common symptom.
study in Journal of Physiology Muscle fatigue is defined as a transient or temporary decrease in the ability to perform physical activities. More specifically, “muscle fatigue” describes any decrease in the force or force that a muscle can produce, that develops soon after the start of physical activity.
You are sure to experience this in your life – whether it’s a lower running speed, your strength when lifting weights, or simply finding it difficult to maintain the same level of performance. Not only can it be frustrating to struggle to maintain a certain level of production, but decreased performance from fatigue can lead to worse training adjustments, as shown in a study from International Journal of Physiology and Sports Performance.
In order to get the most out of your training, let’s take a look at the best ways to prevent muscle fatigue. There are quite a few options (some simpler than others), from training at a sub-maximal intensity to just drinking more water. In that case, you’ll want to check out our guide to The best water bottles.
What is muscle fatigue?
As we have already discussed, muscle fatigue is a decrease in the strength or power that can be produced by the muscles involved in a particular task. In real terms, this manifests itself in the ability to lift less weight or do fewer repetitions, not run/cycle quickly or for too long, or feel the same as performing more difficult.
For muscle fatigue, we only think of decreased performance of the same muscles, essentially the same exercise, or exercises in close proximity to each other; For example, being able to do fewer repetitions of the bench press because you’re doing more sets, or finding it more difficult to maintain a certain pace during your 5K run or running on later days.
Fatigue caused over a longer period of time or with different muscle groups is more likely to be a systemic and directed central nervous system sensation of fatigue, as shown in research into caffeine in American Journal of Physiology.
Causes of muscle fatigue
Before we start discussing the causes of muscle fatigue, we first need to understand what allows muscles to contract and work. At the most basic level, muscles contract by individual fibers (called actin and myosin) that slide over each other, forming cross bridges. A chemical called Adenosine Triphosphate (ATP) is necessary to allow this to happen, and it can be considered muscle currency – the more you have, the more your muscles can work, as shown in Advances in biophysics and molecular biology. Phosphocreatine (PCr for short) is a high-energy chemical that acts as a reserve of phosphate to make more ATP, as shown in muscle physiology.
One reason ATP is important is that it allows calcium to be released from within muscle cells to allow contractions to occur, and an important by-product of ATP formation is the buildup of hydrogen ions, as shown in Talanta. Hydrogen ions cause fatigue by creating a more acidic environment in the muscles.
According to the results of research published in sports medicine And Clinical and experimental pharmacology and physiologyMuscular work can lead to a decrease in ATP and PCr and the accumulation of hydrogen ions and magnesium ions, which prevents the release of calcium. These effects can hinder cross-bridges and calcium release, as a result of which muscle force production is reduced.
The big factor that causes muscle fatigue is the increase in heat that the body is exposed to when exercising. The heat from exercise can cause physiological stress as discussed above, according to a 2015 review in The Scandinavian Journal of Medicine and Science in SportsIt can also lead to dehydration through perspiration as the body tries to maintain a stable, safe temperature.
Dehydration is one of the main causes of fatigue according to a 2011 research paper published in the journal Sports Science JournalAnd sweating can lead to significant losses in essential minerals such as sodium, magnesium and calcium, which can lead to increased muscle fatigue.
How to prevent muscle fatigue
Now that we know the causes of muscle fatigue on a cellular and more general level, there are some well-established and practical steps we can take to help reduce muscle fatigue. First and foremost, eating a few carbohydrates within a few hours of your workout can significantly improve your exercise performance, largely because carbohydrates play a vital role in glycolysis, the primary pathway for ATP production.
Second, there are a number of techniques you can use after a workout to reduce the fatigue you feel from your workout session. 2018 study in Frontiers in Physiology I found that immersion in water at any temperature below body temperature was very effective in reducing fatigue and muscle soreness after exercise.
Finally, a piece of research from 2019 in Journal of Strength and Conditioning Research I found that cooling strategies were one of the most effective ways to maintain performance during exercise, in other words, preventing the core temperature from rising helps prevent fatigue. One very effective way to help maintain a relatively low temperature is to drink cold water, a question investigated in a 2015 meta-analysis in The Scandinavian Journal of Medicine and Science in Sports10 out of 14 studies collected showed a decrease in body temperature by drinking cold water.
Take the main points and practical steps
A certain degree of muscle fatigue is inevitable when exercising, as we wish you could see by now. However, there are some practical steps we can take to minimize the effect, now that we know the causes of muscle fatigue. Eating some carbohydrates before training can help maintain muscle performance, and immersion in water below body temperature can also be beneficial.
Most people already drink water when they exercise, but ensuring it’s cool will go a long way to protecting against muscle fatigue and allowing you to get the most out of your workouts.