What makes muscles grow? - Jeffrey Siegel

We have over 600 muscles that make up between 1/3 and 1/2 of our body weight. They bind us together along with connective tissue and help us move. 

Muscles need constant attention. The way you treat them on a daily basis will determine if they will wither or grow. 

When you expose your body to stress, such as pushing something heavy, your muscles experience microscopic damage. In response, the injured cells release inflammatory molecules called cytokines that activate the immune system to repair the injury. This is when muscle-building happens.

The greater the damage to the muscle tissue, the more your body needs to repair itself. The cycle of damage and repair makes muscles bigger and stronger to adapt to greater demands.

When your body has adapted to an activity, it won't produce enough stress to stimulate new muscle growth. 

• Hypertrophy, an increase in muscular size through exercise, is possible by exposing your cells to higher workloads than they are used to.
• If you don't continuously expose your muscles to some resistance, they will shrink, known as muscular atrophy.
• Exposing the muscle to a high degree of tension while the muscle is lengthening is called an eccentric contraction.

Without proper nutrition, hormones, and rest, your body will not be able to repair damaged muscle fibres.

• Protein in our diet preserves muscle mass. It provides the building blocks for new tissue in the form of amino acids.
• Hormones such as insulin-like growth factors and testosterone shift the body into repair and growth.
• However, this repair mainly happens when we're sleeping.