Imagine that you are lifting weights at the gym. The first time it feels easy, but with each lift, you need to exert more effort until you are unable to continue. The muscles tend to get sore. We often blame lack of energy or lactic acid build-up as prime reasons for the sore muscles. However, there are other factors that are overlooked. In this article, let’s understand the root cause of muscle fatigue.

How Muscles Contract?

In order to understand the roots of muscle movement, it helps to know how a muscle contracts. Muscle contractions happen in response to a signal from the brain and nerves. These signals then travel from the brain to the nerves in the muscle via long thin cells called motor neurons. The motor neuron and the muscle cell have a synapse or tiny gap and it is the exchange of particles across this gap that enables muscles to contract. This whole process happens in a fraction of second.


Muscle contraction process 

On one side of the gap, the motor neuron cells contain a neurotransmitter named Acetylcholine. On the other hand, charged particles or ions – potassium on the inside and sodium on the outside, are present in the muscle cell’s membrane.

When the brain sends the signal, the motor neuron generates Acetylcholine, which in turn, triggers the pores on the muscle cell membranes to open. Sodium ions flow in and potassium flows out. During this exchange of ions, it triggers an electrical charge that spreads through the muscle cell, initiating the release of calcium stored inside it.

It is this flux of calcium that causes the muscles to contract. Calcium stimulates the release of proteins buried inside the muscle fibers to lock together and slide, pulling the muscle tight.

The energy or electrical charge that powers muscle contraction is called ATP. With each muscle contraction, ATP or energy is utilized and waste products like lactic acid are generated and ions are drifted away from the muscle’s cell.

Why Muscles get Fatigued

Even though muscles use ATP energy to contract each time, they are making more and not all of this energy source gets depleted. Several acidic waste and residues are also generated, whilst the tissue is still effectively trying to clear the waste.

Eventually over the course of time, what happens in the cells is that the sodium-potassium pump gets exhausted or sufficient calcium molecules may not be available near the muscle cell’s membrane to power the contraction properly. Therefore even if the brain sends a signal for the muscle to contract, it may not be able to trigger an appropriate response.

That is when you pause and with a little break, the depleted ions of Sodium, Potassium or Calcium flow back to the required areas. Muscle fatigue tends to subside for a bit as these ions replenish themselves.

The More you Exercise the Less Fatigue

Have you ever noticed that if you don’t exercise regularly and suddenly start to work up a routine, muscles tend to get sore and fatigue seeps in? This is because of the failure to exercise regularly. The more you exercise regularly, the longer it takes for muscle fatigue to set in each time.

This is because the stronger you are, the fewer times the process of brain signal to muscle contraction has to be repeated to lift weights. Fewer cycles of this process, in turn, leads to slower ion depletion.

Therefore as your physical fitness improves, you will be able to exercise longer at the same intensity. Also, muscles tend to grow with exercise and so there is scope for more energy to be stored and a higher capacity of the tissues to clear the waste. This will help to push muscle fatigue farther and farther.

Tips to Fighting Muscle Fatigue

Muscle fatigue is a normal side-effect of exercise as you start to build a routine. But don’t let it dampen your spirits. It is the sign that your body is reaching a threshold and adapting to a fitness regimen. Here’s how you can fight fatigue:

1. Rest/ Recovery

Each time you exercise, ensure to do a warm-up and cool down to get your muscles working and relax. Start off slowly and gradually increase the intensity to give ample time for your muscles to adjust. Also, allow adequate rest between strength repetitions and listen to your body’s signal.

2. Proper Body Mechanics

Use the correct form and posture while exercising, paying attention to muscle imbalances and incorrect movement. Improper body mechanics also tend to pull down your efficiency burning more energy than necessary and generating more acidic waste as well.

3. Build Endurance

Improve your aerobic capacity gradually with interval training, alternating between bursts of slow-moderate-high-slow intensity to improve your lung capacity. This will also help you to avoid muscle fatigue by promoting oxygenation, energy release and prevent lactic acid build-up.

4. Hydration

Keep yourself hydrated to promote the sodium-potassium pump that enables muscle contractions in your body. This will make up for electrolyte loss and muscle fatigue. While exercising, drink water at the right intervals and don’t drink water immediately before or after the workout.

5. Nutrition and Healthy Eating

Sodium, potassium, and calcium are important compounds that your body needs to contract the muscles properly. Ensure the get the right balance of sodium and potassium in your diet by eating plenty of vegetables and fruits. At the same time, it is not recommended to work out on a full stomach or empty stomach. Eat a light meal at least a couple of hours before the workout and eat within an hour after the workout to repair and replenish the muscles.

6. Quality Sleep

Sleep is very vital to recover and repair your muscles. So, never overlook a proper sleep routine when it comes to the prevention of muscle fatigue. Get good quality deep sleep to help your body replenish and increase the chances of muscle repair. However, avoid eating before sleeping to give ample time for digestion to take place and enable the stomach to take rest.

Muscle fatigue is the last thing you want to deal with while working out. Understanding the science behind muscle contractions and providing the body the right conditions will enable you to prevent muscle fatigue.