How does exercising make your muscles bigger and stronger?By cwan | July 18th, 2018
Skeletal muscles such as biceps, pectorals, and quadriceps are the muscles attached to the skeleton; they are responsible for pulling the skeleton and generating movement—they are literally how we move. These muscles are composed of very long, thin cells that include the full sets of cellular components needed for general functions. However, more than 90 percent of the total volume of a skeletal muscle cell is composed of muscle proteins, including the contractile proteins—actin and myosin. When a muscle cell is activated by its nerve cell, the interaction of actin and myosin generates force through power strokes. The total force a muscle generated depends on the sum of all the power strokes occurring simultaneously within all the cells of the muscle.
Research has shown that two processes appear to account for the mechanism by which exercise enhances strength: hypertrophy and neutral adaptions.
Hypertrophy refers to the enlargement of muscle cells. Enlarged muscles cells lead to that sought-after “bulging muscular” look. Research has shown that muscle cells subjected to regular bouts of exercise followed by periods of rest, with sufficient dietary protein, undergo hypertrophy as a response to the stress of training. Dietary protein provides amino acids, the building blocks for muscle protein. Enhanced muscle protein synthesis and incorporation of these newly synthesized muscle proteins into cells cause hypertrophy: i.e. enlarged muscle cells. Because there are more potential power strokes associated with increased actin and myosin concentrations, the muscle can exhibit greater strength.
Neural adaptations refer to enhanced nerve-muscle interaction. In untrained muscle, the cells take turns firing in an asynchronous manner. Training enhances a process called synchronous activation, meaning training increases the body’s ability to recruit more muscle cells — and thus more power strokes — in a simultaneous manner. In addition, training decreases inhibitory neural feedback, a natural response of the central nervous system to feedback signals arising from the muscle. Such inhibition keeps the muscle from overworking and possibly ripping itself apart as it creates a level of force to which it is not accustomed. This neural adaptation mechanism can generate significant strength gains with minimal hypertrophy (i.e. muscle cell enlargement) and is responsible for much of the strength gains seen in women and adolescents who exercise. In addition, because neural adaptation utilizes nerve and muscle cells already present, this mechanism also accounts for the strength increases recorded in the initial stages of training.
Because hypertrophy depends upon the creation of new muscle proteins, it is a much slower process. Thus, it is important to adhere to an exercise regime involving both the vigorous exercise and strength building session as well as resting intervals to achieve muscle building effect and producing stronger and bigger muscles.
Thanks for reading.
Dr. Connie Wan