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Is Muscle Damage Related to Muscle Hypertrophy?

There has been considerable debate about the role of muscle damage in hypertrophy, with some stating it is a mechanism influencing muscle growth, while others that it occurs during muscular work but is not causative for hypertrophy. Deepika Chowdhury, a molecular biologist and IFBB figure pro tries to address this confusion in this article.

Is Muscle Damage Related to Muscle Hypertrophy?

Do you ever wonder if muscle damage due to resistance training is related to muscle hypertrophy? To put it more simply, do you think more muscle soreness will mean more muscle growth? If the lab work is done to find the answer then at what time muscle protein synthesis can predict hypertrophy? Is it that muscle protein synthesis rises in response to resistance training in the initial phase, just after training or at later time points? And is it due to muscle damage? Is it that muscle damage is highest after a training bout and it decreases over time?

There has been considerable debate about the role of muscle damage in hypertrophy, with some stating it is a mechanism influencing muscle growth, while others that it occurs during muscular work but is not causative for hypertrophy. Let me share with you the findings of research work done to answer this confusion.

The conclusion of these studies suggests that muscle damage is not related to hypertrophy. But there are no studies suggesting that muscle damage has direct negative effect on hypertrophy. But first let’s look at some brief explanation of few terms used in this article without getting too technical.

Muscle Protein Synthesis (MPS): The rate at which new proteins are added to the muscle. Methods like chemically labeled amino acids are infused via catheters and traced to determine the rate at which they are incorporated into muscle. Even better, the participants drink deuterium oxide (heavy water, 2H2O) and measure “deuterated” amino acids that are incorporated into muscle samples.

Repeated bout effect: It is a phenomenon in which the muscle is protected against damage from future muscular work when it performs repeated bouts of the similar task.

Methods to detect muscle damage: Subjective methods like rating soreness on a scale of 1-100, estimating creatine kinase (blood marker of muscle damage), compare isometric voluntary contractile strength (tends to decline when muscle damage is high), microscopic examination of biopsy to assess mechanical disruption of actin-myosin cross bridges.

One of the studies done by Stu Phillip (16 weeks training study) found no relationship between MPS after first session and hypertrophy. One of the ground breaking studies was done by Damas et al. and I would like to emphasize this study because of its long duration (10 weeks), study design and methods employed.

They found growth in muscle fibers by week 10. Muscle damage was the highest after the initial training session, lower by week 3, and the lowest at week 10. MPS was highest after the initial session and lower by week 3, which remained the same at week 10. Fiber growth had a very strong relationship with MPS at week 3 and 10 but had no relationship with MPS after the first training session.

Thus, MPS in the earliest stage of resistance training is not primarily directed toward muscle growth but towards repair work of muscle damage. Muscle growth and MPS are only strongly related once muscle damage decreases.

Yet this study doesn’t answer whether muscle damage is “good or bad,” but shows that muscle damage is not related to hypertrophy. This study also measured the strength difference due to muscle damage which was decreased by approx 22% for 48 hours after the initial bout.

However after the repeated bout effect taking place, strength was decreased by only 2-6% in the 48 hours after the bouts in weeks 3 and 10. This was confirmed by the decrease in both direct and indirect markers of muscle damage in weeks 3 and 10 of the training.

Although this study doesn’t answer if repeated bout effect is good or bad thing but it definitely shows that if efforts are not made to benefit from the repeated bout effect (detraining, changing exercises, gradually increasing work volume to acclimate the body to workload, introducing mesocycles etc) the strength is acutely decreased by muscle damage, which will decrease the ability to produce progressive overload. 

In summary, muscle hypertrophy is the result of accumulated intermittent increases in MPS mainly after a progressive attenuation of muscle damage. The initial muscle protein synthesis data is high in response to resistance training (within ~48 hours) because of muscle damage repair work and not because of muscle hypertrophy. But after repeated bouts of training (after multiple weeks of training) the muscle damage is decreased.

At this time point muscle protein synthesis is highly predictive of hypertrophy. Also, muscle protein synthesis data cannot be an indicator of muscle growth potential of your implemented nutrition plan or training protocol when substantial muscle damage is present.

Therefore, rushing into a high-volume or high-intensity training approach, relative to what you were previously doing, can hamper progress due to degradation of strength from excessive muscle damage. Knowing the lack of a relationship between hypertrophy and damage, we can conclude that we should not purposefully seek out muscle damage in training.

To avoid the detrimental effects of excessive muscle damage, the best strategy can be gradually acclimate yourself to higher levels of volume and intensity as needed to progress. Further studies are required to clearly answer the riddle of whether muscle damage has any direct negative role or causative role as an additive towards muscle hypertrophy.

About The Author

Deepika Chowdhury

She is a Pune based athlete, she is India’s first female figure IFBB Pro. India’s first female to be invited by Arnold Classic, Australia to represent India. Certifi.. Read More..


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