An update on nitric oxide supplements: a direct link to lean muscle gain

If you’ve spent any time in a supplement store, you’ve undoubtedly come across nitric oxide (NO) supplements. They are part of every gym monkey’s pre-workout stack and are easily one of the most popular supplement categories out there.

For years manufacturers and scientists have touted NO’s ability to boost exercise performance and increase energy. These two benefits have largely been thought to be the reason for the link between NO and lean muscle gains.

Scientists are now discovering a more direct link between NO and hypertrophy (i.e. muscle growth).

How increased blood flow stimulates muscle growth

Skeletal muscle, the type of muscle you use when you exercise, is made up of many bundles of muscle fibers.

Muscle fibers, in turn, are bundles of myofibrils.

Oxygen is supplied to muscles by arteries. When you exercise, blood flow to the active muscle increases because the muscle needs more oxygen.

More blood flow causes fluid to pool in active muscles. This fluid pooling is what you probably recognize as a good swell when you’re working out.

When fluid builds up, it strains a structure within muscle cells called the sarcolemma. The strain then stimulates protein synthesis and hypertrophy. AKA your muscles get bigger over time.

Fluid build up is linked to hypertrophy through another mechanism too. Fluid build up threatens the structure of the whole muscle cell. To adapt and preserve its structure, the muscle cell will expand (get bigger).

How NO supplements work

NO is a small molecule. Its primary purpose in the body is to increase blood flow.

You can’t take NO directly. It’s a gas and it degrades into nitrogen and oxygen in about 5 seconds. NO supplements don’t actually contain NO. Instead, they contain ingredients that promote NO production from cells in the body.

These are things like L-arginine and L-citrulline.

Ingestion of L-arginine and L-citrulline promote the synthesis of NO, which increases blood flow.

How NO increases lean muscle gain

NO supplements increase lean muscle gain by increasing blood flow to working muscles. The increase in blood flow results in more fluid pooling, which strains the sarcolemma and threatens the structural integrity of the muscle cell. The muscle responds by getting bigger.

Sources and further reading

Effects of dietary sports supplements on metabolite accumulation, vasodilation, and cellular swelling in relation to muscle hypertrophy: A focus on “secondary” physiological determinants.

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