Debunking the Great Micro Tear Myth and an Introduction to Mechanical Tension
Tags: @Histy @Eggshells @Yun @God @Sayori
Feel free to discuss in the replies
Hello and Welcome to my first High Effort thread on this forum, since its my first time if you could point out any mistakes i have made it would be much appreciated.
For years it has been said by PTs, Exercise Physiologists and Gym Bros alike that microtears are the main driver of muscle hypertrophy, its still taught in colleges and schools, however its a big fat LIE, yes you heard me microtears are NOT the main driver for muscle hypertrophy, but rather something called Mechanical Tension is.
The Microtear theory explains that Muscle Hypertrophy occurs when the muscle recieves tiny tears after exercise which triggers an inflammatory response which leads to the muscle being strengthened and repaired
The first reason why microtears are NOT the main driver of muscle hypertrophy is because muscles become less susceptible to damage with repeated exercise
For example in this study where they assesed whether "Pain" is neccesary for "Gain", in this study it is shown that "Muscle damage/Muscle soreness is not necessarily indispensable for exercise-induced muscle adaptation." therefore another mechanism must be a greater driver for Muscular Hypertrophy.
source
This is further supported by the fact a repeated bout effect has been consistently reported where EIMD (Exercise Induced Muscle Damage) is attentuated in the first bout of exercise and becomes less increasingly prevalent after.
Another reason as to why microtears aren't the main driver of hypertrophy is that Blood Flow Restriction (BFR) Training leads to hypertrophy with minimal muscle damage.
for example in this study they investigated the effects of 2 daily sessions of BFR training at a low intensity (20% of 1RM) on Muscular hypertrophy, what they found was that "There was a gradual increase in circulating IGF-1 and muscle-bone CSA (Cross sectional area)" and concluded that "skeletal muscle hypertrophy and strength gain occurred after two weeks of twice daily LIT-Kaatsu training."
source
In a similar study it was shown there was no considerable muscle damage coming from low intensity occlusion training
6 subjects performed bilateral leg extensions with their thigh compressed performing the exercise at 20% of their 1 Rep Max (1RM) the results showed that "extremely light resistance exercise combined with occlusion greatly stimulates the secretion of GH through regional accumulation of metabolites without considerable tissue damage."
source
This shows hypertrophy still occured with minimal amounts of muscle damage meaning that EIMD has a smaller role in hypertrophy than it is described to have
For example in this study where they assesed whether "Pain" is neccesary for "Gain", in this study it is shown that "Muscle damage/Muscle soreness is not necessarily indispensable for exercise-induced muscle adaptation." therefore another mechanism must be a greater driver for Muscular Hypertrophy.
source
This is further supported by the fact a repeated bout effect has been consistently reported where EIMD (Exercise Induced Muscle Damage) is attentuated in the first bout of exercise and becomes less increasingly prevalent after.
Another reason as to why microtears aren't the main driver of hypertrophy is that Blood Flow Restriction (BFR) Training leads to hypertrophy with minimal muscle damage.
for example in this study they investigated the effects of 2 daily sessions of BFR training at a low intensity (20% of 1RM) on Muscular hypertrophy, what they found was that "There was a gradual increase in circulating IGF-1 and muscle-bone CSA (Cross sectional area)" and concluded that "skeletal muscle hypertrophy and strength gain occurred after two weeks of twice daily LIT-Kaatsu training."
source
In a similar study it was shown there was no considerable muscle damage coming from low intensity occlusion training
6 subjects performed bilateral leg extensions with their thigh compressed performing the exercise at 20% of their 1 Rep Max (1RM) the results showed that "extremely light resistance exercise combined with occlusion greatly stimulates the secretion of GH through regional accumulation of metabolites without considerable tissue damage."
source
This shows hypertrophy still occured with minimal amounts of muscle damage meaning that EIMD has a smaller role in hypertrophy than it is described to have
Mechanical Tension is defined as the stress applied to a muscle, passively and actively.
It works when a load is applied to a muscle causing Mechanoreceptors in the muscle to detect the applied force and convert the mechanical signals to chemicals signals through Mechanotransduction, then a cascade of intracellular enzymes (e.g. mTOR) start facilitating anabolic processes, this then drives up muscle protein synthesis which would exceed muscle protein breakdown which is when hypertrophy occurs
It works when a load is applied to a muscle causing Mechanoreceptors in the muscle to detect the applied force and convert the mechanical signals to chemicals signals through Mechanotransduction, then a cascade of intracellular enzymes (e.g. mTOR) start facilitating anabolic processes, this then drives up muscle protein synthesis which would exceed muscle protein breakdown which is when hypertrophy occurs
Source 1
"Mechanical tension is the primary and essential driver of resistance-training–induced musclehypertrophy through mechanotransductive signaling, independent of systemic hormonal fluctuations."
Source 2
"Research is very clear: Micro-tears are not the primary driver of muscle growth, mechanical tension is."
This "source" is for the appeal to authority gymbros as Arnold Schwarzenegger himself says microtears arent the primary driver of muscle growth
Source 3
"Current research suggests that maximum gains in muscle hypertrophy are achieved by training regimens that produce significant metabolic stress while maintaining a moderate degree of muscle tension."
"Mechanical tension is the primary and essential driver of resistance-training–induced musclehypertrophy through mechanotransductive signaling, independent of systemic hormonal fluctuations."
Source 2
"Research is very clear: Micro-tears are not the primary driver of muscle growth, mechanical tension is."
This "source" is for the appeal to authority gymbros as Arnold Schwarzenegger himself says microtears arent the primary driver of muscle growth
Source 3
"Current research suggests that maximum gains in muscle hypertrophy are achieved by training regimens that produce significant metabolic stress while maintaining a moderate degree of muscle tension."
In conclusion Mechanical Tension is the Main Driver of hypertrophy as the mechanical load applied causes mechanotransduction to occur raising muscle protein synthesis through anabolic processes facilitated by Enzymes, And microtears have a greatly overstated role in hypertrophy.
Tags: @Histy @Eggshells @Yun @God @Sayori
Feel free to discuss in the replies