What is muscle? How do they work? How do they get bigger?

Yes, everyone knows what a muscle is… in the sense that we all have them and we need them to move around…. BUT have you ever actually wondered what muscles actually are and how they work?

A lot of us probably take our muscles a little for granted. They are literally our ‘engine’. Our ideas and thoughts manifest in the brain but in order to convert those ideas into action we need muscles. Feel like smiling? For that you need all your facial muscles. Type a text message? You need the muscles in your fingers and arms. Want to dance around in your underwear? You need almost every muscle in your body to do that.

Clinically speaking ‘muscle’ is a bundle of fibrous tissue in a human (or animal) body that has the ability to contract, to produce movement within the body. Most people think biceps or triceps when they think of muscles, these are examples of ‘skeletal muscle’. Skeletal muscles are not the only types of muscles we have. In fact there are 3 types. Did you know that the heart is actually a muscle? Cardiac muscle is found only in the heart. The third type is smooth muscle which is found in our organs such as stomach, intestines and bladder.

For the purpose of this blog we are going to focus on SKELETAL muscle. That’s what we (as physios) treat, and also what many of us flog ourselves in the gym to tone & sculpt. Skeletal muscles attach to the skeleton (bones) and bring about movement of our limbs. Contraction of these muscles is almost always voluntary meaning that you think about using them. The exception is cramps or muscle spasm!

We have two types of skeletal muscle: Type I fibres or ‘slow twitch’ fibres: Known as red muscle, these muscles can contract for a long period of time but with little force. They carry more oxygen so are used for aerobic activity. Type II fibres of ‘fast twitch’ fibres: Known as white muscle, these fibres contract very rapidly & with greater force but fatigue quickly. They are used for short anaerobic bursts of activity.

To make our muscles move (or contract) we need electrical impulses which travel from the brain via our nervous system. There are a series of complicated processes involving ions & so on but I think that’s getting a little too technical.

Putting aside natural growth progressions our muscles get bigger as a result of stresses put through the body during exercise. When the amount of stress is greater than what your muscles are used too there will be an increase in muscle tension which in turn causes changes down at a biochemical level. This progressive stress also causes muscle ‘damage’ which is the reason why we get sore the day after a hard workout.
TheUpper Pecs_0 body then works to repair this ‘damage’ by forming new muscle strands. The increase in number and thickness of muscle fibres results in muscle hypertrophy or growth. It is important to note that this process of growth occurs during rest not while you are actually lifting weights!With this in mind it’s only goes to say that rest & nutrition are both vital to the recipe for building bigger muscles. Your muscles need protein for recovery & repair but also need carbohydrates to replenish glycogen stores following a workout. Poor nutrition is one of the biggest mistakes people make when trying to build muscle mass.

Finally there is the effect of hormones. Testosterone increases protein synthesis, inhibits protein breakdown & stimulates other anabolic hormones. Strength & resistance training releases testosterone into the body which can then increase levels of growth hormone both of which contribute to tissue growth.

Keep in mind there are certain factors such as genetics, age & gender than can impact on how much your muscles can grow, which is why females don’t have as much muscle mass as their male counterparts. Muscle growth takes time with visible changes taking at least 4 weeks to come about. To stimulate growth you need to place stresses on your body that it’s not adapted to through heavy weights & mixing up your exercise program. This induces muscle damage and will stimulate the ‘rebuilding’ process which contributes to overall muscle bulk.

As we age, our muscle mass naturally decreases (along with other things such as bone density etc) watch out for upcoming blogs on why it’s so important to maintain adequate levels of both these things!!

Have a great week!


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