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Athletes and fitness enthusiasts often encounter a rather unwelcome visitor: muscle fatigue. The sensation of tired, achy muscles after a good workout can be both frustrating and debilitating. The signs of muscle fatigue are uncannily similar to those of injury or overuse, and both require different approaches while addressing them.
The key is to identify tired muscles from injury. For that, an understanding of how muscles tire, and how we can take care of them after exercise is important. Deciphering the science of muscle fatigue can also help you significantly improve your workout efficiency.
The science of muscle fatigue
Muscle fatigue is a complex phenomenon – during exercise, muscles contract and generate force through a series of intricate interactions between nerve impulses and fibers, utilizing energy. One of the primary contributors to muscle fatigue is the depletion of energy stored within the muscle cells.
“Muscles get tired because the storage energy levels decrease with exercise,” says Dr Mithun Sai Sundar, orthopaedician, Fortis Malar Hospital, Chennai. “Usually, energy is stored in the form of creatine in the muscles.”
Creatine compounds act like a store house from which ATP (adenosine triphosphate) is delivered to the muscles. ATP is the energy stored in the muscles which fuels their contractions.
“When muscles get tired it means energy in the form of ATP is depleted,” adds Dr Sundar. “Throughout repetitive muscle movement, the muscles contract and relax. There are two filaments, actin and myosin present in the muscles which pull each other during contractions. While pulling together they need ATP which is stored in the form of creatine. When you exercise, these filaments just keep on pulling and retracting and they hit a limit.”
The muscles have limited ATP stores, which are rapidly depleted during high-intensity activities. The body must then rely on other energy sources, such as creatine phosphate and glycogen, to regenerate ATP, leading to a temporary decline in muscle performance.
Another significant factor which affects muscle fatigue is the extent to which the muscles are adapted to use ATP efficiently.
“When the muscles are not well trained, which means, if you compare somebody who’s not working out versus somebody who’s an exercise person, or a sportsperson versus a non-athlete, the non-athlete is likely to get more tired because the muscles are not adapted to physical activity,” says Dr Tvisha Parikh, consultant sports and exercise medicine physician at Sir HN Reliance Foundation Hospital, Mumbai. “When somebody exercises, their muscles get adapted to the movement, but when somebody is not exercising the muscles are not adapted to use ATP very efficiently which leads to tiredness.”
When the intensity of exercise exceeds the muscle’s capacity to generate energy aerobically, the body turns to anaerobic pathways, leading to the accumulation of lactic acid and other metabolites and that may contribute to soreness, stiffness and other classic symptoms of muscle fatigue.
Using muscle fatigue to improve fitness
“Have you noticed that people who go to the gym for the first time experience more pain and fatigue than the people who go regularly to the gym,” elaborates Dr Sundar. “It’s all about adaptation, and the body adapts well. If you do excessive exercise the muscle will get sore. Soreness is due to the wear and tear of the muscle fibers and the body builds them back. That’s why we call it bodybuilding and building requires bricks and stones, that’s where nutrition comes in. You must not overdo it, rather take it step by step and increase the nutrients, which are the basic raw materials.”
Pushing the muscles to their limit during exercise is necessary for growth and improvement. The aim is to challenge the muscles and experience fatigue to stimulate physiological adaptations that lead to increased strength, endurance, and overall fitness.
However, it is crucial to listen to our bodies and respect the signs of fatigue. Understanding the difference between normal muscle fatigue and pain due to injury or overuse can help you stay away from much serious injuries as well as overtraining.
Muscle fatigue is not a barrier but rather a stepping stone towards achieving fitness goals. Embrace the fatigue and use it as a catalyst for growth and progress on your fitness journey.
Takeaways
- One of the primary contributors to muscle fatigue is the depletion of energy store (ATP) within the muscle cells.
- Another reason could be that your muscles are not well adapted to use ATP efficiently. When you are not working out the muscles are not adapted to using ATP efficiently, and this leads to tiredness.
- Pushing our muscles to their limits’ during exercise is necessary for growth and improvement. The key is to challenge the muscles and experience fatigue to stimulate physiological adaptations that lead to increased strength, endurance, and overall fitness.
- Understanding the difference between normal muscle fatigue and pain due to injury or overuse can help you stay away from serious injuries as well as overtraining.
