Have you ever been training in the gym and noticed the 120kg monster standing at 8% body fat, lifting weights more suited to your grandma Nora? Most likely you would have seen this a few times. Although a person’s genetic make up will always play a huge part when dealing with muscle hypertrophy, we have to consider that the discrepancy in the overall strength and look of muscle tissue can also be due to the different training parameters and programs undertaken to achieve a specific response. Does the 120kg monster need to be lifting heavy all the time? Hell no, he`s providing an adequate stimulus to provide the given response to his goals (his goal is to increase the visual size of his muscle tissue)! Let`s look at the difference between Myofibril and Sarcoplasmic Hypertrophy.
Myofibrillar hypertrophy refers to an actual increase in size of the muscle fibers, which contract and generate force via the actin and mysosin filaments within the muscle tissue. With Myofibrillar hypertrophy, the area density of the myofibrils increases and there is an increase in potential to exert muscular force, so therefore when working at a higher % of 1RM on a given lift, producing sufficient force and speed will help with maximum motor recruitment and syncronisation. Under the correct parameters (Training experience, programming, etc) and given the right stimulus, the body will recruit more motor units than it actually requires (Over-Compensation), which is a good thing! This type of hypertrophy is best accomplished by training with heavy weights for a minimum number of repetitions. Repetitions in the 1-6 rep range, using 80-100% of a 1 rep max also have the added benefits of neural adaptations: increased motor unit synchronisation, increased contractibility of the actin and myosin filaments, inhibition of the GTO (Golgi Tendon Organ). Myofibrillar hypertrophy mainly takes place within the fast twitch muscle fibres due to their physiological make up and contractile properties.
Sarcoplasmic hypertrophy is an increase in the total volume of the non contractile properties of the muscle tissue, known as sarcoplasmic fluid. The increase in total volume of sarcoplasmic fluid and blood within the muscle causes the myofibrils to swell and tear and therefore if the stress and stimulus is sufficient enough then the correct adaptation will occur….increase in muscle size! This type of training is high volume, high repetitions and is what is seen in the “Bodybuilding community”. Utilising the correct exercise tempo, known as time under tension (TUT) is a method which works very well, muscle tissue respond to a given stress not necessarily weight (if correct tempo is used). This is why your 120kg bodybuilding friend isn’t using the weights your “expecting” him to use.
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