“Why is it so hard for me to gain weight?”
The answer to this question can be down to a variety of reasons. Of course, one of these is genetics. Genetics plays a part in our capacity to gain and lose weight. There are three main types of muscle fibres. Everyone has a mixture of all three but one type is usually predominant in each person.
The three main types of muscle fibres:
- Type I
- Type IIa
- Type IIb
Let us examine these three types of muscle fibres.
Type I – Endurance type athletes have lots of Type I muscle fibre. It consists of slow twitch, oxidative fibres that are resistant to fatigue.

Samuel Wanjiru of Kenya.
Type IIb – Sprinters and weightlifters usually have a lot of this type of muscle fibre as their sport requires a tremendous amount of power and quick energy. It consists of extremely fast twitch muscles that fatigue easily.

Yegeny Chigishev of Russia.
Type IIa – This is the middle ground between the two previous muscle fibres. Middle distant runners and swimmers would benefit from having a lot of this muscle fibre as they need a fair amount of explosive energy as well as endurance.

Michael Phelps, USA.
If you find it difficult to gain weight this could be because you have a predominance of Type I muscle fibre. This post is not to discourage you in your quest to build muscle but to give you a realistic expectation of the progress you can expect to make. As long as you train consistently and properly you can overcome any genetic limitation.
April 17th, 2011 → 7:45 pm
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