With enough training, a perfect diet, mental fortitude, and the right equipment… and any of us could be an elite athlete, right? While I would like to say, “of course, you can do anything!”, it turns out that genetics plays a role in athleticism as well.
After reading through a bunch of studies on the genetics of elite athletic performance, I’ve come away with an overall sense that for some people, athleticism will just come easier. For others, it will take a little more work.
To be honest, your genes are probably not the limiting factor for your athletic performance unless you are at the very top of your sport. Even at the top levels, there are always exceptions.
Moreover, reading through some of the research leaves me a bit disconcerted. Some of the research reads as almost a ‘how to’ guide for selecting people for a sport based on their genetic profile.
First, a couple of terms to define:
Power sports are generally ones that require short bursts of power. Examples include sprinting, weight lifting, short track biking, and gymnastics. Generally, these sports require more anaerobic muscle power. [ref]
Endurance sports include long distance running, distance cycling, long-distance swimming, and cross-country skiing.
While the genetic variants listed below may make a difference between winning or not at the Olympic level, don’t let the lack of a ‘good’ genetic variant dissuade you from a sport you love.
Muscle composition is partly genetic. We all know people who put on muscle easily, and other people who are long and lean, well suited for running. This doesn’t mean that people who are long and lean can’t put on some muscle mass with weight lifting, but it does mean that they may not put on as much muscle mass as quickly as others.
The composition of muscle fiber (slow twitch vs fast twitch) has been shown to be about 45% due to genetics and about 40% due to the environment (exercise, nutrition, etc.). [ref]
Studies show that the amount of slow-twitch (Type I) muscle ranges from 5 – 90% in thigh muscles. Slow twitch muscle is best suited for long endurance and aerobic exercise – example: long-distance runners. Type IIX muscle fibers (fast twitch, glycolytic) are more suited to power sports and strength training.[ref]
This section covers the research on different genetic variants that impact muscle composition such as muscle fiber type and muscle development. Additionally, I’ve written another article on ACTN3 and ACE genes.
The renin-angiotensin system regulates fluids and blood pressure in the body through the release of renin from the kidneys.
The AGTR2 gene codes for the angiotensin 2 receptor, which is involved in blood pressure homeostasis – and in the development of skeletal muscle.
Studies on AGTR2:
Another gene within the renin-angiotensin system that has been associated with athletic performance is the AGT gene, which codes for the protein angiotensin. This protein is involved in controlling blood pressure and electrolyte balance in the body. Angiotensin is a precursor to the angiotensin II protein which also acts as a skeletal muscle growth factor.
Studies on AGT show:
IL-6 (interleukin 6) is an inflammatory cytokine that is important in the immune response. In addition to fighting off pathogens, it is also involved in muscle repair after high-intensity exercise. An increase in IL6 seems to be an advantage for building muscle through exercise. While often we try to limit inflammation, this is one case where the inflammatory process is beneficial.
Studies on IL-6 and muscle building:
Myostatin is a peptide that is secreted by skeletal muscles and regulates the increase in muscle mass. The MSTN gene codes for the myostatin protein. Basically, increased myostatin inhibits muscle growth.
Double-muscled cattle (right) are caused by a mutation in the myostatin gene that decreases myostatin production. (If you are wondering why all cows are bred to have the double myostatin mutation, it also causes increased problems with pregnancies and the need for more expensive feed.)
Studies on the rs1805086 variant have reported that the C allele is associated with greater muscle mass. This variant is found in 11-31% of African Americans and <5% of Caucasians. [ref]
A study of ‘explosive leg power’ (squats, jumps) in non-athletes found that the C allele of rs1805086 was associated with worse performance. [ref]
Nitric oxide (NO) is a free radical gas that acts as a relaxant for blood vessels. It is synthesized from the amino acid arginine using the enzyme nitric oxide synthase. NOS3 gene codes for the endothelial nitric oxide synthase (eNOS). Nitric oxide is important in muscle metabolism and control of skeletal muscle function and structure. eNOS is important for the vascular function in muscles, delivering oxygen during exercise.
Studies on the NOS3 gene and athletes:
The AMPD1 gene codes for a form of the enzyme adenosine monophosphate deaminase (AMPD) which is found in the skeletal muscle. This enzyme is used in the muscles when under stress from exercise. It is part of the conversion process of AMP to IMP. A common variant of the AMPD1 gene decreases the conversion, leading to a build-up of AMP. This can actually be a benefit for people with heart disease. [ref]
AMPD1 is mainly expressed in fast-twitch muscle fiber. When it comes to exercise, people with decreased AMPD tend to get sore more easily after a hard workout. As one study puts it, people with the genetic variant that decrease AMPD get “muscle cramps, pain, and premature fatigue during exercise”. [ref]
About 11% of Caucasians carry one copy of the AMPD1 variant () that leads to decreased function. About 2% carry two copies of the variant, that eliminates AMPD function altogether. The frequency varies in other populations with about 1% of Africans carrying one copy of the variant and less than 1% of Asians carrying the variant.
Studies on the AMPD1 gene and athletes:
There are several specific ‘hacks’ that may benefit your athletic performance based on your genetic variants.
Beet juice has been shown in quite a few studies to benefit athletic performance by increasing nitric oxide. Not all studies agree, but a meta-analysis showed that the majority of evidence points to an effect on NO from beets, which are high in inorganic nitrate. [ref] You can juice fresh beets for a pre-workout drink, or there are beet juice powdered supplements available as well. Look for an organic option if possible. (Amazon – organic beet juice powder)
If you carry the AMPD1 deficiency allele, it may help to supplement with d-ribose before and during a workout. The d-ribose won’t necessarily decrease your exercise capacity, but it takes away the muscle soreness afterward.[ref][ref] D-ribose is a type of sugar and can be purchased in a powdered form. It has a mild, sweet taste and could be added to anything you drink during a workout. (Amazon – pure d-ribose powder)
If you don’t carry the myostatin variant that increases muscle mass, adding a natural myostatin inhibitor to your diet may give you a minor benefit.
Creatine plus resistance training has been shown to decrease myostatin (thus theoretically increasing muscle gain). [ref][ref] Creatine is a common bodybuilding supplement. Be sure to look for one with no extra junk added to it. (Amazon – pure creatine)
The flavonoid -epicatechin has been shown in studies to decrease myostatin and increase muscle strength. It is found in green tea (EGCG) extract and cocoa. [ref] EGCG can be taken as a supplement (Amazon – EGCG capsules). I’m sure you can figure out ways to incorporate more cocoa into your diet…
If you carry the IL6 variant associated with lower IL6 levels, you may be at an advantage for a lot of chronic conditions that are worsened by inflammation. But… you may not build muscle as quickly after resistance training. Thus, you may want to avoid IL-6 inhibitors, if possible, when you train.
Some natural IL-6 inhibitors that you may want to avoid include a lot of the ‘healthy’ anti-inflammatory supplements. Quercetin is a natural IL-6 inhibitor, so avoid turmeric or golden tea right before or after your workout. [ref] Andrographis is another IL-6 inhibitor. [ref] And EGCG (from green tea) is also an IL6 inhibitor that you may want to avoid around the time of your workout. [ref]