What Causes Muscle Mass?
Muscle mass is the interaction of 6 different factors. These help to maintain and develop muscle mass. They include genetics, nervous system activation, environmental factors, endocrine influences, nutritional status and physical activity.
Changes in muscles become detectable after only 3 weeks of training. However, these changes are not yet noticeable to the eye. Overload training increases the size of the muscle fibres with subsequent muscle growth.
The fast twitch fibres of weight trainers average roughly 45% larger than those of an endurance athlete or a healthy sedentary person. Muscle growth is the result of repetitive muscle fibre injury, this is particularly apparent in the eccentric action of a movement. After this, an over compensation of protein synthesis occurs to produce a net anabolic effect (the muscle cells thicken and increase in number).
A single form of resistant training will never create an equal strength throughout the muscle. Bicep curls performed at 1-RM (one rep max is the maximum amount of force that can be generated in one contraction) will not produce equal strength gains from the origin (shoulder) to the insertion (over your elbow). Muscle need to be worked through different exercises, intensity and angles.
Physiological adaptations to resistance training:
♦ Number of Muscle Fibres = Increase
♦ Strength of Muscle Fibres = Increase
♦ Mitochondria Volume + Density = Decrease
♦ Ligament Strength = Increase
♦ Tendon Strength = Increase
♦ Basal Metabolism = Increase
♦ Collagen Content of the Muscle = No Change
♦ Percentage of Body Fat = Decrease
♦ Lean Body Mass = Increase
♦ Bone Density + Mineral Content = Increase