How hiit promotes muscle growth
HIIT workouts can build muscle, tone, and help retain lean muscle mass, as well as increasing the proportion of fast-twitch muscle fibres over slow-twitch. For muscle growth, choose mainly strength training rather than cardio routines.
stimuli of growth
To build muscle you need to endure mechanical tension, muscle fatigue, and muscle damage. When you lift a heavy weight, contractile proteins in muscles generate force and apply tension to overturn the resistance. This mechanical tension is the main driver of hypertrophy (muscle growth). This tension can result in structural damage to the muscles. Mechanical damage to muscle proteins stimulates a repair response in the body. The damaged fibres in muscle proteins result in an increase in muscle size. Mechanical fatigue occurs when the muscle fibres exhaust the available supply of ATP (adenosine triphosphate;), the body’s energy molecule that helps your muscles contract. They aren’t able to continue fuelling muscular contractions or can no longer lift the weight properly. This metabolic stress can also lead to muscle gain.
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MECHANISMS OF MUSCLE GROWTH
satellite cells
Skeletal muscle satellite cells are considered to play a crucial role in muscle fibre maintenance, repair, and remodelling. These mononucleated cells are “wedged” between the base membrane and plasma membrane of the muscle fibre. These act as stem cells and are responsible for the further growth and development of skeletal muscles. Satellite cells go into a state of dormancy due to a sedentary lifestyle.
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The decline of muscle mass with age
If you don’t use them, you lose them... or they will go dormant. Our satellite cells naturally reduce in number as we get older, but training counteracts this decline. It’s important for people to activate their muscles on a regular basis once they reach the age of 30, or face the possibility of losing the ability to regenerate muscle mass as they age.
How muscles get bigger
Skeletal muscle protein cycles through periods of synthesis and breakdown on a daily basis. Muscle growth occurs whenever the rate of muscle protein synthesis is greater than the rate of muscle protein breakdown. Muscle hypertrophy is thought to be a collection of adaptations to different components – the myofibrils, the sarcoplasmic fluid, and the connective tissue.
MUSCLE fibre BEFORE GROWTH
The circle represents a muscle in cross-section with its bundle of fascicles. Within there are many myofibrils and surrounding them is sarcoplasmic fluid and a layer of connective tissue.
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myofibrillar hypertrophy
Myofibrillar protein makes up 60–70 per cent of the protein in a muscle cell. Myofibrillar hypertrophy is the increase in number and/or size of myofibrils by the addition of sarcomeres.
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sarcoplasmic hypertrophy
A rise in the volume of the sarcoplasm (which includes mitochondria, sarcoplasmic reticulum, t-tubules, enzymes and substrates, such as glycogen) also enlarges the muscle.
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connective tissue hypertrophy
The extracellular matrix of the muscle is a three-dimensional scaffolding of connective tissue. Increases in its mineral and protein content lead to muscles getting bigger.
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