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The Key Role of Mechanical Tension in Muscle Growth

Updated: Jul 13, 2023

Introduction:


Muscle growth is a complex process influenced by various factors. Among these factors, mechanical tension plays a crucial role in stimulating muscle fiber growth. In this blog post, we'll delve into the significance of mechanical tension, its relationship with fatigue, and its dominance over metabolic stress and muscle damage in promoting muscle growth.


Understanding Mechanical Tension:


Mechanical tension can be likened to a pulling force experienced by muscle fibers when they attempt to shorten but encounter resistance. The intensity of this force increases as the shortening velocity decreases. Consequently, muscles experience significant mechanical tension when subjected to high degrees of resistance during contractions.


Fatigue and Muscle Contractions:


During repeated muscle contractions, fatigue sets in, causing the muscle fibers governed by the working motor units to lose their ability to generate the necessary force. To compensate, higher threshold motor units are recruited, activating their associated muscle fibers. Additionally, fatigue leads to a reduction in the contraction velocity of working muscle fibers over the course of the set. This decrease in velocity is closely tied to the level of metabolic stress within the muscle.


Mechanical Tension and Muscle Growth:


In fatiguing sets with any load, the activation of high threshold motor units, which typically develop after strength training, becomes prominent. The muscle fibers associated with these motor units contract at a slow speed. As a result, the muscle fibers experience mechanical tension due to their slow shortening velocity, thereby stimulating growth.


Role of Metabolic Stress and Muscle Damage:


It is challenging to investigate the independent effects of metabolic stress and muscle damage on muscle growth, as they are intricately connected to mechanical stress. The impacts of fatigue and greater mechanical loading can explain the effects typically associated with metabolic stress and muscle damage. Therefore, the primary focus should be on understanding and optimizing mechanical tension.


The Dominance of Mechanical Tension:


With all roads to muscle growth leading to mechanical tension, the role of metabolic stress and muscle damage becomes secondary. The model for muscle growth revolves around the tension produced and detected in each muscle fiber. Hence, it is advisable not to overly concern ourselves with the contributions of metabolic stress and muscle damage in the context of muscle growth.


Conclusion:


Mechanical tension, characterized as a pulling force experienced by muscle fibers during contractions, is a key driver of muscle growth. Fatigue-induced increases in mechanical tension, along with the recruitment of high threshold motor units and the resulting slow contraction speed of muscle fibers, contribute significantly to muscle growth. While metabolic stress and muscle damage are related factors, their effects can be explained within the framework of mechanical tension. By understanding and optimizing mechanical tension, we can effectively promote muscle growth.


Remember, when it comes to building muscle, mechanical tension is the primary mechanism to focus on.



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