What is the function of Nitric Oxide?

Nitric Oxide (NO) is a hormone that enhances blood flow to the muscle, which has a significant effect on muscle building and mass gaining.

When you exercise, a neurotransmitter called acetylcholine causes calcium to be released in the muscle fibers, triggering the enzyme nitric oxide synthase to produce nitric oxide from the amino acid arginine. The nitric oxide hormone subsequently exits the muscle fiber and attaches to cells lining the veins and arteries.

This causes the veins and arteries to dilate, allowing more blood to reach the muscle and resulting in a pump. What's fascinating about muscle pumps is that they're not just for looks and ego - and while we can all appreciate how amazing a full-on arm pump looks and feels with a tight shirt on - increased blood flow supplies more oxygen and nutrients to the exercising muscle while also removing waste products.

This increases the effectiveness of your training and allows you to recover from the set faster. All of this blood is working to eliminate lactic acid, carbon dioxide, and any other byproducts of muscular contraction, and to exchange these waste products for the energy and nutrients the muscle requires to continue the contraction process. During future sessions, you will be able to lift more weight.

Likewise, if your muscle is packed with blood, it is getting bigger. Stretching the fascial tissue that is constricting the muscle allows it to expand or hypertrophy within the tissue. To some extent, the pump will accomplish this. The stretching of the outer layer is responsible for some of the "pleasant pain" you may feel from a huge muscle pump. Like a balloon filling with air, expanding this strong network of connective tissue surrounding muscle gives your muscles more room to grow.