Author: Troy Theodosiou

Genetic factors influence the rate and quantity of muscle growth for an individual throughout his or her resistance training program. Muscle growth is influenced by muscle fiber type, fat distribution, hormone levels and the quality and duration of your exercise program. Although you cannot change your genetic makeup, you can design a muscle-building routine that will be the most successful for your genetic ability to develop enhanced muscle strength and size.

The human body produces two types of skeletal muscle fibers—slow-twitch (type 1) and fast-twitch (type 2). The fast-twitch fibers contract many times faster and with more force than the slow-twitch ones do, but they also fatigue more quickly. Each of these muscle types can be further broken down into subcategories, depending on contractile speed, force and fatigue resistance. Type 2B fast-twitch fibers, for example, have a faster contraction time than type 2A.

Muscles can be converted from one subcategory to another but cannot be converted from one type to another. This means that endurance training can give type 2B muscle some of the fatigue-resistant characteristics of type 2A muscle and that weight training can give type 2A muscle some of the strength characteristics of type 2B muscle. Endurance training, however, will not convert type 2 muscle to type 1 nor will strength training convert slow-twitch muscle to fast. Endurance athletes have a greater proportion of slow-twitch fibers, whereas sprinters and jumpers have more of the fast-twitch variety.

It is easy to go to the gym and just work on what you are good at, but it takes discipline to work on what is a struggle. Take legs for instance. If your legs are small and weak and everyone in your family has small and weak legs, this should be your focal point when it comes to training. If you want bigger legs you have to train hard, harder than others who may just have genetically bigger legs.

Everyone has issues with genetics that have to be dealt with. Some people are predisposed to carrying extra fat, some are lean, some have trouble building muscle and some are muscular but not very strong.

The truth is no one has perfect genetics! Genetic factors influence the rate and quantity of muscle growth, but that should never be used as an excuse in the gym. We all have weak areas so instead of wasting valuable time complaining about them rather get to work on improving them!