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Genetics & Bodybuilding

How Much Influence Do Genetics Have In Bodybuilding & Other Sports

Posted by TimeIsMuscle - August 5th, 2016

Genetics have a significant impact on the results we seek in all kinds of physical activity. There’s no getting away from it. Before we consider the effect genetics has on athletics, let’s first address the effect our genetic predisposition has on those of you who are interested in pursuing or practising bodybuilding.

Body Types

You’re probably familiar with the three known body types (Somatotypes): Ectomorph, Mesomorph and Endomorph, but in case you aren’t, let’s break it down.

  • Ectomorphic – skinny. Ecto’s have a thin build with lean muscle and smaller joints.
  • Mesomorphic –athletic build. Meso’s have large bone structure, large muscles and an athletic physique.
  • Endomorph – soft & round build. Endo’s gain fat easily and tend to be a shorter build, with thick arms and legs.

NOTE: In some cases people may have a combination of two body types.

If you’re of mesomorphic predisposition, you may find building muscle easier than if you are of ectomorphic or endomorphic. This is not to say those of you who are born with ectomorph or endomorph body types can’t have successful results in bodybuilding, it just means you may need to work harder.

Some examples of famous bodybuilders who defied their body type to become world-class athletes are Frank Zane (ectomorph) and Jay Cutler (endomorph). Arnold Schwarzenegger was a mix between an ectomorph and a mesomorph – an ecto-mesomorph, if you will.

The Struggles For Ectomorphs & Mesomorphs

Ectomorphs have a fast metabolism, so gaining weight is difficult. Therefore ectomorphs need a large amount of calories every single day. Their workouts should be short and intense, focusing on large muscle groups. When it comes to cutting, these guys have the advantage of burning fat easier thanks to their metabolism.

Endomorphs tend to have a much slower metabolism, and therefore generally store fat much more easily than an ecto or mesomorph. Cardio is super important for endomorphs, and they need to be very smart with their diet (such as consuming more protein) in order to keep fat levels low. Endomorphs may also have lack of muscle definition. One possible solution here is a “Bodybuilding reversal”, to cut and then bulk.

Genetics & Sports Performance

Genetics shape us in many ways, including our potential to excel in sports. Training, diet, and other factors play a large role in developing our potential, but our genes may also limit performance. Genetics have a large influence over strength, muscle size and muscle fibre composition (fast or slow twitch), anaerobic threshold (AT), lung capacity, flexibility, and endurance.

Muscle fibre types, for example, can determine what sports you’re most likely to excel in and perform better at. That’s not to say muscle fibres can’t be altered through training to help you succeed in your sport of choice though. Let’s quickly look at the characteristics of different muscle fibres.

  • Red Type I – slow to contract and slow to tire. Good O2 supply (i.e. long distance runner, marathon, cross country etc).
  • Red Type IIa – fast to contract, long term anaerobic capacity, with slightly better O2 supply than that of Type IIb (i.e. 200m sprinter).
  • White Type IIb – Very fast to contract, fast to tire, short term anaerobic capacity with poor O2 Supply (i.e. 100m sprinter, powerlifter etc).

One major limitation for endurance athletes is their heart’s ability to deliver enough oxygen from the bloodstream to the working skeletal muscles, otherwise known as one’s “cardiac capacity”. This also is largely influenced by genetics. The other limitation for endurance athletes is the ability of muscle tissue to effectively use oxygen and create ATP, otherwise known as adenosine triphosphate (which is the fuel that permits muscular contraction and movement). The efficiency of this process is measured by VO2 max, which is the maximum volume of oxygen.

How Genetics Influence Response To Training

Your genes may also determine how your body responds to training, diet and other external factors. For example, some people respond to aerobic endurance training better than other types of training. So even if you have a low genetic potential for aerobic endurance, you may respond well to that type of training. Therefore, by further developing your potential, you may perform better than someone who just has the “potential genetic talent” on its own, in absence of training.

Training regularly, as you probably already know, increases cardiac efficiency. However, the extent of this increase may depend heavily on your genetics.

Genetically gifted athletes will have a much better response to training and will have a larger increase of mitochondria within their cells. Mitochondria are organelles in cells (or a subunit if you will, within the cell) with a specific job to produce the ATP. Therefore the more mitochondria a person has, the more efficient they become.

Other Factors That Effect Sports Performance

Genetics arguably have less influence over our motor skills such as balance, agility, reaction time and accuracy in terms of our ability to perform at specific sports. Many of these skills can be greatly improved with carefully constructed nerve to muscle training regimes.

Sports Nutrition

Diet and nutrition has a significant effect on our athletic performance. You must consider what foods you should or should not be eating to help you achieve your goal. This is commonly evident when athletes "hit the wall" during an event or competition. This is generally a result of glycogen depletion, dehydration, or a combination of both. Athletes can avoid this by strategically training the body to burn fat as their glycogen storages decrease, and by continually providing working muscles with energy during an event or other physical activity.


Aside from building bigger muscles, bodybuilding is a classic example of an individual demonstrating the ability to find ways to overcome what might be considered “genetic flaws”. It is evident that specific training and attention to dietary requirements can help you achieve your specific goals, whether it is to run a marathon, achieve a new PB in Olympic lifting, or build an aesthetic looking physique. I believe it is possible to make great personal achievements, even if you appear to lack the genetic foundation on paper.

NOTE: The subject of muscle fibres and nutrition in sport will be covered more in-depth in future articles, in order to give a more comprehensive understanding of these elements.

Related Videos:

Scott Herman / Erica Stibich- GENE RESULTS! Are You Using The Right Training Routine & Nutrition?

7 Muscle Building Mistakes Natural Lifters Make!

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It's said that ectomorphs have the hardest time gaining muscle. Generally, compared with other body types, ectomorphs have smaller...


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Good stuff! Always helps to identify your body type when you start training.


A very informative article @time_is_muscle! Nice!!


excellent article