To understand what causes muscle fatigue, it is necessary to understand what is muscle fatigue. If you exercise regularly, you may be familiar with a feeling of dull muscle pain or a feeling of fatigue or lack of energy, which makes it difficult to perform normal daily tasks. But not only can exercise cause muscle fatigue, some health conditions also call muscle fatigue a common symptom.
Research in Journal of Physiology defines muscle fatigue as a transient or temporary decrease in the ability to perform physical actions. More specifically, “muscle fatigue” describes any decrease in strength or power that muscles can produce that develops shortly after the start of physical activity.
You’ve probably experienced this in your life – whether it’s when you reduce your running speed, your strength when lifting weights, or just because it’s harder for you to maintain the same level of performance. Not only is it difficult to maintain a given level of performance, but a decrease in performance caused by fatigue can lead to impaired training adaptation, according to a study International Journal of Sports Physiology and Performance.
To get the most out of your workouts, let’s look at how best to prevent muscle fatigue. There are several options (some easier than others), from workouts with submaximal intensity to simply drinking more water. In this case, you should read our guide the best water bottles.
What is muscle fatigue?
As we have discussed, muscle fatigue is a decrease in the strength or power that can be produced by the muscles involved in this task. In real terms this is manifested in the fact that you can lift less weight or do fewer reps, not run / ride a cycle so fast or so long, or feel more challenging.
As for muscle fatigue, we only consider decreased performance for the same muscles, and primarily during a single workout or workouts in close proximity to each other; for example, the ability to perform fewer reps in a bench press when you do more approaches, or you find it harder to maintain a set pace while running 5km or jogging in the following days.
Fatigue caused over a longer period of time or with different muscle groups is likely to be a systemic feeling of fatigue focused on the central nervous system, as shown in a study of caffeine in American Journal of Physiology.
Causes of muscle fatigue
Before we start discussing what causes muscle fatigue, we first need to understand what allows muscles to contract and work. At the most fundamental level, muscles contract by individual fibers (called actin and myosin) that slide one after the other and form transverse bridges. A chemical called adenosine triphosphate (ATP) is needed for this to happen, and it can be thought of as muscle currency – the more you have, the more your muscles can work as shown in Advances in biophysics and molecular biology. Phosphocreatine (abbreviated RCC) is a high-energy chemical that acts as a reserve of phosphates to produce more ATP, as shown in Muscle physiology.
One of the reasons why ATP is so important is that it allows calcium to be released from muscle cells to make contractions occur, and an important byproduct of ATP creation is the accumulation of hydrogen ions, as shown in Talent. Hydrogen ions cause fatigue, creating a more acidic environment in the muscles.
According to research published in Sports Medicine and Clinical and experimental pharmacology and physiology, muscle work can cause a decrease in ATP and PCr and the accumulation of hydrogen and magnesium ions that inhibit calcium release. These effects can interfere with cross-switching and calcium release, and result in decreased muscle strength production.
A huge factor that causes muscle fatigue is the increase in heat felt by the body during exercise. Exercise-induced heat can cause physical exertion, as mentioned above, according to a 2015 review. Scandinavian Journal of Medicine and Science in Sportand can also lead to dehydration through sweat as the body tries to maintain a stable and safe temperature.
Dehydration is a major factor in fatigue, according to a 2011 article Journal of Sports Scienceand sweating can lead to significant loss of essential minerals such as sodium, magnesium and calcium, which can lead to more muscle fatigue.
How to prevent muscle fatigue
Now that we know what causes muscle fatigue at the cellular and more general level, we can take some sustainable practical steps to help reduce muscle fatigue. First of all, consuming certain carbohydrates for a few hours after a workout can greatly improve exercise performance, mainly because carbohydrates play a vital role in glycolysis, the major pathway for ATP production.
Second, there are a number of tactics you can use after your workout to reduce your workout fatigue. The 2018 study Frontiers in physiology found that immersion in water at any temperature below body temperature was very effective for reducing fatigue and muscle pain after exercise.
Finally, 2019’s study Journal of Strength and Conditioning Research found that cooling strategies were one of the most effective ways to maintain performance during a workout, in other words, preventing too high a core temperature helps prevent fatigue. One of the very effective ways to maintain a relatively low temperature is to drink cold water, a question explored in a 2015 meta-analysis. Scandinavian Journal of Medicine and Science in Sportand 10 of 14 compiled studies showed a decrease in body temperature when drinking cold water.
Take home points and practical steps
Some degree of muscle fatigue is inevitable with exercise, which I hope you see now. However, there are some practical steps we can take to reduce the effect, now that we know what causes muscle fatigue. Eating carbs before a workout can help maintain muscle performance, and immersion in water below body temperature can also be helpful.
Most people already drink water during workouts, but ensuring that it is cold will have a big impact on protecting against muscle fatigue and allow you to get the most out of your workouts.