The Basics: Muscle Fiber Type and Athletic Ability
Human muscle fibers can be classified into two categories. Slow-twitch (red) muscle fibers and fast-twitch (white) muscle fibers. You’ve probably heard of the different muscle fiber types before, but you may not have realized that each muscle type’s predominance is determined by genetics.
The ACTN3 (Alpha Actinin) gene is only active in fast-twitch (white) muscle fibers, and plays an important role in their function. This gene is frequently inactive due to a gene mutation that reduces the function of white muscle fibers and therefore the explosive power produced by the muscles. The red muscle fibers increase the stamina of the muscles.
Each individual has two genes that produce ACTN3, and the following gene combinations are possible:
Endurance type: both genes are inactive and don’t produce ACTN3 protein (24% of population)
Power type: one of the genes is active and produces ACTN3 protein (44 % of population)
Power type: both genes are active and produce ACTN3 protein (31% population)
The second sports gene, ACE (Angiotensin Converting Enzyme), plays an important role in blood pressure regulation.
ACE has two forms: the endurance sports variant of the ACE gene, which has a positive effect on endurance of the muscles (found in elite marathon runners) and the power form of the ACE gene, which makes the muscles more suited to power and sprinting. Every individual has two genes of this type with following possible combinations:
Endurance – both genes endurance (25% of population)
Endurance – one gene endurance, one power (50% of population)
Power – both gene power (25% of population)
If both genes are present, a general genetic predisposition to a particular mix of endurance and strength training, which can vary greatly from person to person, occurs. This knowledge can influence the individual training program, depending on the type of sport performed.
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Stefanovic Mina
Oxygen Uptake (VO2max) — Your genetic capability to absorb oxygen through the lungs and transport it to the appropriate muscles.
Maximum aerobic capacity — aka VO2max — it is the amount of oxygen the human body can use when a person is running or cycling at full speed. It is determined by how much blood the heart pumps, how much oxygen the lungs get into the blood, and how powerful the muscles are in the uptake and use of oxygen from the blood that is flowing around them. The body needs more energy and therefore more oxygen during exercise. If there is not enough oxygen in the cells, energy conversion is slowed down and performance drops. The more oxygen a person can use, the better their stamina.
Statistical analysis shows that half of an individual’s ability to improve their aerobic capacity through training is determined exclusively by their parents.
A few years ago, there was a breakthrough in sports genetics. More than twenty gene variants (F.e.: NRF2, VEGF, ADRB2, CRP…) were discovered that predict the inherited component of the aerobic improvement of an individual. These genetic markers define people with high and low response to training. Individual differences in aerobic training are predicated by genes involved in immune and inflammatory processes in the body. However, there are certain genetic variations that increase the VO2max level considerably and therefore create a better starting point without any training. Some of the best endurance athletes in the world are almost always born in better shape than their colleagues.
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Inflammatory response and injuries — Certain genes control the aggressiveness of the immune system and can lead to a higher risk of injury.
During excessive exercise, the tissue is slightly damaged in many places. The immune system normally recognized this as a normal process and there is no inflammation or swelling. Certain genes control the aggressiveness of the immune system. In case of errors, there is a problem and strong inflammatory reaction.
COL1A1 and COL5A1 are the genetic codes of proteins of which collagen fibers, the basic building blocks of tendons, ligaments and skin, consist. Collagen is actually the glue of the human body that keeps connective tissue in the right form. Variations in collagen genes influence both flexibility and the risk of injury to the connective tissue in an individual (such as breaking the Achilles tendon).
The only thing we can tell athletes with a certain genetic profile is that they are subject to a higher risk of injury based on our current knowledge. You can modify any training you are currently doing to minimize the risk, or you can do “pre-rehabilitative” workouts to strengthen the risk area.
Oxidative stress and athletes
Athletes produce considerably more free radicals (that can damage the tissue) because they consume more energy during intensive exercise. These molecules affect your health and athletic performance so negatively. Your body has certain genes that can recognize and neutralize these molecules. Many people have genetic variations in these genes that disturb the function and the protection.
Certain micronutrients – antioxidants – can compensate for the missing protection (if they are in the right dose). It is therefore possible to test the appropriate genes and compensate for any genetic weakness with the right dose of micro-nutrients, regardless of the result. The results are included oxidative stress in cells, recommended dose and substance of antioxidants, ect.
Perception of pain in sport
Genes affect how we perceive pain. Bearing and managing pain is essential for most elite athletes. The bodies of some people somehow “slacken” and will no longer let them give top performances. Due to the genetic differences between individuals, none of us can really recognize the physical pain of another person. COMT – is the gene most commonly investigated as a participant in pain relief. It is part of the metabolism of neurotransmitters in the brain, including dopamine. The enzyme Catechol-O-Methyltransferase (COMT) can deactivate various substances (adrenaline, noradrenaline, dopamine, estrogen) and direct them to degradation. In addition, COMT can block the effect of various drugs.
Two common versions of COMT are depending on whether one particular part of the DNA sequence in this gene encodes the amino acid valine or methionine. Based on cognitive testing and brain imaging studies, it was discovered that people with two Methionin versions tended to be more successful and consumed less metabolic effort in cognitive and memory tasks, but were simultaneously more susceptible to anxiety and more sensitive to pain. Carriers of two Valin are a little less successful in cognitive tasks that require rapid mental elasticity, but they can be more resilient to stress and pain.
In situations of acute stress, the brain blocks pain (stress-induced analgesia) to fight or flee without having to think about a broken bone. The system for blocking pain in extreme situations developed in genes and is also manifested in sport. A sports match can trigger a “flee or fight” mechanism. When you get into a battle you care about, you activate this system. The ability of an athlete to cope with pain is a complex combination of inborn and taught.
The role of genes in head injuries
Gene APOE (Apolipoprotein E) plays a central role in human metabolism. Occurs in three frequent variants called E2, E3 and E4. The E4 is associated with an increased risk of heart disease and Alzheimer’s disease. The meaning of this gene determines too, how well one can recover from any brain injury. For example, ApoE4 carriers who suffer head injuries in traffic accidents are in coma longer, suffer more bleeding and bruising, have more frequent seizures after injury, less rehabilitation success, and are more likely to suffer from permanent consequences or die.
The ApoE gene is involved in the inflammation of the brain following trauma, and in people with the ApoE4 variant it takes longer. Several studies have found that athletes with the ApoE4 variant who suffer a blow to the head take longer to recover and are at risk of developing dementia later in life. You cannot prevent athletes from doing their sports, but you can at least help by watching them closely. ApoE4 probably doesn’t increase the risk of concussion, but it can affect recovery from it.
Genes and sudden death in sports
Nitric oxide synthase 1 adapter protein (NOS1AP) is an adapter protein and allows interaction with other molecules. His variants are associated with a prolonged QT interval on ECG and increased risk of sudden cardiac death. The following risk factors contribute to the development of QT prolongation in ECG and arrhythmias: Congenital disposition to QT prolongation, the administration of multiple QT prolonging drugs simultaneously, hypokalemia and other electrolyte and acid-base disorders, organic heart disease and some other factors. The QT interval is inherited to some extent, and women are more at risk than men to QT prolongation.
People with left ventricular hypertrophy, heart failure, an impaired internal environment and other factors are more at risk of QT prolongation. It appears that one of the most common causes of QT prolongation is medication. Examples of drugs that prolong the QT interval: ZOFRAN (ondansetron), TENSAMIN (dopamine), ADRENALIN (epinephrine), KLACID (Clarithromycin), SUMAMED (azithromycin), NIZORAL (ketocenazole), SEREVENT, SERETIDE (salmeterol), PROTAZIN (promethazine). When two or more drugs are administered that can individually prolong QT, the side effects in the form of QT prolongation are added
Sometimes it is enough to receive one of the drugs that can prolong QT while another substance is administered which, although it does not itself prolong QT, increases the plasma concentrations of the first drug, potentiating its side effects, including QT prolongation. The other substance may not even be a drug, such as grapefruit juice.
