In men it seems the upper body such as the traps, shoulders, and arms grow more easily. In women, the lower body such as the glutes and legs grow more easily.
Ever wondered what the easiest muscle to build and grow is? Me too, so I researched why certain muscles would be easier to grow than others.
It seems to easiest muscles to grow are upper body muscles such as the arms, shoulders, back and chest in men.
And in women, the easiest muscles to grow are in the lower body such as the legs and glutes.
However, there is more to it than this and it's not that simple, genetics are only one factor.
Reasons for an Easily Growing Muscle
Some muscles may grow more easily than other muscles due to a multitude of reasons, and it varies dramatically in different people.
However, there are two main reasons a muscle may grow more easily than other muscles, as listed below.
Genetics
In terms of genetics there are multiple reasons one muscle may grow faster than another.
In terms of androgen receptors, men have more androgen receptors in the upper body than in the lower body.
This means most men find it easier to build muscle in the arms, shoulders, back and chest than they do in the lower body and legs.
Women, on the other hand, have less androgen receptors altogether, but have a higher density of androgen receptors in the lower body, meaning the legs and glutes would grow more easily in women.
This is simply due to genetics and androgen receptor densities in different areas of the body.
Another genetic reason is the type of fibres your muscles have.
Your body is made up of many types of muscle, cardiac, smooth and skeletal muscle; however, only the skeletal muscle is what we're interested in.
Skeletal muscle is usually made up of three or four major types of specific and specialised muscle fibres, as listed below.
Type 1
Type 2a
Type 2b
Type 2x
Below is a table comparing the qualities and characteristics of each of these muscle fibre types.
Type 1 | Type 2a | Type 2x | Type 2b | |
Contraction Time | Slow | Fairly Fast | Fast | Very Fast |
Size of Motor Neuron | Small | Medium | Large | Very Large |
Resistance to Fatigue | High | Fairly High | Medium | Low |
Activity Used For | Aerobic | Long-Term Anaerobic | Short-Term Anaerobic | Short-Term Anaerobic |
Max. Duration of Use | Hours | <30 Minutes | <5 Minutes | <1 Minute |
Power Produced | Low | Medium | High | Very High |
Mitochondrial Density | High | High | Medium | Low |
Capillary Density | High | Medium | Low | Low |
Oxidative Capacity | High | High | Medium | Low |
Glycolytic Capacity | Low | High | High | High |
Major Storage Fuel | Triglycerides | Creatine Phosphate, Glycogen | Creatine Phosphate, Glycogen | Creatine Phosphate, Glycogen |
Interestingly, these different types of muscle fibres have different rates of hypertrophy and growth.
So, which type of muscle fibre grows the easiest?
Usually, the faster twitch type a muscle fibre is, the larger it would be to begin with and the more potential and ease of growth there is.
Therefore, it would make sense the faster twitch muscle such as those in the upper body, such as the chest, arms and shoulders would grow faster.
The quadriceps also have a higher percentage of fast-twitch muscle fibres, the calves and soleus having the least amount of fast-twitch fibres.
Have you seen bodybuilders with small calves? This is probably why, they have a high percentage of slow-twitch muscle fibres in the calves, meaning it's very hard to grow.
Despite the fact that muscle growth is significantly affected genetically, it does not provide a definitive solution to this question.
Usage of certain muscles and lifestyle also play a large part in muscle growth.
Usage
Have you seen a bodybuilder with small legs? Or have you seen a professional gymnast with a strong core and ripped abs?
Most likely you have. There is a reason for this, they train specifically for certain movements. The more you do something, the better you will be at it.
No matter how good or bad your muscle-building genetics are, if you only train one specific movement, providing you correctly train, you'll adapt and grow accordingly.
A lot of this is due to social stigma and expectations. Men are constantly published on social media with ripped abs, big arms and a built chest.
Women are shown to have bigger legs and glutes and smaller upper bodies.
You should train for your desired goal, don't let social expectations get in your way.
Which Muscle Is the Easiest to Develop?
There is not one single answer, but in terms of genetic differences for men, it seems the upper body has a tendency to grow faster and more easily than the lower body.
Upper body muscles that tend to grow faster include the biceps, triceps, chest, back, shoulders and neck.
In women, genetically, the lower body seems better equipped to grow muscle than the upper body.
Lower body muscles that grow more easily in women include the quadriceps, hamstrings and glutes.
Although a lot of this is due to social and lifestyle reasons.
Further Reading
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