How muscles grow

Understand the six-step process behind hypertrophy and make greater gains

If you want to build a better body then adding muscle mass, in combination with reducing body fat levels, is the fastest way to make the biggest possible changes to your physique. The process of building new muscle tissue, which is called “hypertrophy”, is essentially your body’s response to the stress of lifting weights and other forms of weight-bearing exercise. In simplistic terms, your body thinks: “Wow, that was tough. We’d better get stronger so it’s not so hard next time.”

When you perform resistance training exercises, such as those featured in the New Body Plan Plus personalised training programme, you cause microscopic tears in your muscles. Your body deals with this “muscular microtrauma” by overcompensating: the damaged tissue is repaired and more tissue is added, making your muscles bigger and stronger so the risk of future damage is minimised.

Over time, following a progressive training programme you will build more muscle tissue while stripping away body fat to transform your physique. Here’s the step-by-step process of what happens during the hypertrophy process.

1 Warm up
During your workout warm-up your heart rate increases and blood is pumped into your muscles, warming them up and allowing them to extend fully. The blood also supplies the muscle fibres with oxygen. At the start of a rep, your muscles are under tension and stretched. As a result more blood is pumped into the protective sheaths of the muscle fibres, supplying even more oxygen and nutrients.

2 Systems go
As you lift a weight, your central nervous system (CNS) relays this to the nerves in the sheaths around the muscle fibres, telling the fibres to contract. If you do the exercise correctly your muscles will activate in a particular sequence, which your CNS adapts to. As you repeat the workout, your CNS gets more efficient, allowing you to do more. This is the first adaptation caused by weightlifting.

3 Chain reaction
Adenosine triphosphate (ATP) is the immediate energy source for these muscle contractions. It is broken down within the cells to release energy. The cells’ creatine phosphate and glycogen reserves are also converted into ATP. This process creates lactic acid as a by-product.

4 Feel the burn
Once the glycogen stores in your cells have been depleted and lactic acid starts to build up the muscle can’t work efficiently, so you have to rest. As you do so, aerobic (oxygen-based) muscle respiration occurs, processing the lactic acid back into glycogen and providing more energy for the next set.

5 Fail to succeed
As you reach the last rep of the last set of a given exercise, your fast-twitch muscle fibres should be approaching complete fatigue. Microscopic tears (microtears) occur in the myofilaments, which are the smallest fibre bundles in your muscles.

6 Repair and grow
Your muscles start to grow during the post-workout repair process. Your body fixes the microtears by adding the amino acids actin and myosin to the myofilaments, which also causes them to grow. Your muscles adapt to store more glycogen too, so there’s more energy for the next workout. This also makes your muscles bigger.

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