People go to the gym not only to lose fat but also to gain muscle. Bodybuilders hone their muscles in order to attain the body shape and size they want. There are 650 skeletal muscles in the human body. These muscles receive signals from the motor neurons that are triggered from the parts of cells known as sarcoplasmic reticulum. Upon receipt of these signals, the muscles contract.


People are able to lift heavy objects due to their ability to activate the motor neurons that will signal the muscles to contract. People have different abilities to activate their motor neurons, which explains why they have different lifting capabilities. A person can be small in physical stature, but he can have more lifting power due to his ability to better activate his motor neurons.

Physiology of Growth

After a strenuous activity such as a workout, damaged muscle fibers are repaired. This occurs through the cellular process that fuses muscle fibers together in order to form new myofibrils, which are strands of muscle protein. The repaired myofibrils add volume to the muscles, resulting in muscle hypertrophy or growth. There will be muscle growth when the rate of muscle protein synthesis exceeds the rate of muscle protein breakdown. Interestingly, this process does not occur during the time you lift weights as you might expect. Rather, it occurs while your muscles are at rest.

Mechanisms of Growth

Muscle growth occurs when people continuously put more stress on the muscles. Muscle stress disrupts the stable equilibrium or homeostasis in the body. The muscle stress and disruption result in the mechanisms that allow muscle to grow as follows:

  • Muscle tension – When an amount of stress greater than what your muscles are previously accustomed to is applied, the body’s muscles will grow. Progressively lifting heavier weights puts additional tension on the muscles, allowing for the activation of the growth process.
  • Muscle damage – Feeling sore after a workout means that the muscles involved suffered damage. The damage to the muscles caused the release of inflammatory molecules and the activation of the growth process. Feeling sore is not necessary, but the damage from the workout is needed for muscle growth.
  • Metabolic stress –This causes the swelling of cells around the muscles that were involved in the workout, contributing to muscle growth without increasing the size of the muscle cells. The swelling is due to the added muscle glycogen that helps in the sarcoplasmic hypertrophy or the appearance of larger muscles.

The breakdown and growth of muscles occur when you force them to adapt to progressive levels of stress. This can be achieved by lifting weights progressively as you exercise, providing more stress and damage to the muscles. This must be followed by adequate rest and ample fuel to the muscles in order for them to recover and grow.