This gene encodes for the protein (homeostatic iron regulator) which is essential for the regulation of iron absorption. Iron in turn is essential for energy metabolism, and transportation of oxygen to the tissue from the blood, hence influencing the endurance activity.

The ACE gene plays a role in the production of an enzyme (angiotensin II) which controls blood pressure and balances the fluid and salt in the body. Certain variants of this gene can help in making better improvements during higher intensity training. Certain variation of the ACE genes shows a greater response to strength endurance training.

The ADRB2 gene influences how sensitive our body can be to the effects of adrenaline. Variations in the ADRB2 gene can affect heart rate, and lead to increased blood to be pumped around the body, which transports oxygen and nutrients to muscles; it can increase the size of the windpipe, thereby allowing more oxygen to be taken in. The ADRB2 gene expresses throughout the cardiovascular, respiratory, metabolic, and musculoskeletal systems, along with increasing the breakdown of fat (lipid metabolism), which acts as a fuel during exercise, thus influencing endurance performance.

The PPARA gene is important for the production of a protein which in turn activates other genes and also regulates the oxidation of fatty acid during exercise. This gene has an effect on the body's response to various exercises; when cells are deprived of sufficient energy during certain conditions that use up the body's energy stores, e.g. during exercise, the PPARA gene is activated. Variants of the PPARA gene may influence the endurance sports activity of the athlete.

The PPARGC1A gene plays a role in the production of a protein that has beneficial effects on the body, following exercise. PPARGC1A affects oxygen utilization and muscle fatigue and certain variants of the PPARGC1A gene may influence the endurance performance; it also has a direct effect on skeletal muscle function during a marathon, hence affecting the lactate threshold.

GABP1 is a genetic marker in endurance athletes. The GABPB1 gene plays a role in the production of Nrf2 protein. As a response to exercise and the increased in the demand for energy in the muscles, Nrf2 protein improves respiratory capacity and increases the rate of ATP (energy) production. Therefore, variants of the GABPB1 gene may influence the aerobic capacity for endurance athletes.

The VEGFA gene plays a role in the production of a protein that is crucial in the process of exercise-induced angiogenesis, which is the formation of new blood vessels brought on by exercise. Variations of this gene can influence VO2max before and after aerobic exercise training hence influencing the endurance status of the athlete.

The MCT1 gene codes for a protein that is responsible to transport lactate across the cell membrane which is of prime importance in skeletal tissues. The MCT1 gene also influences the transport of molecules used to produce ATP; the energy currency of the cells. Studies have associated a variant of MCT1 with endurance athlete status and blood lactate level after intensive exercise.

A variant of NOS3 gene is associated with the production of an enzyme (eNOS) that affects nitric oxide production, which in turn influences the process that can help regular blood pressure (endothelium-dependent vasodilation) in response to exercise. Higher energy expenditure can significantly increase the activity of the NOS3 gene and vasodilation associated with physical activities. Some variants are associated with endurance performance.

The PPARD gene encodes for a protein that can affect energy production. In muscle tissues, the expression of this gene is increased due to exercise, which can result in increased fat burning capacity and an increase in type I muscle fibers. Type I muscle fibers are the main group of muscles used in activities such as distance running, cycling, swimming, and endurance training.

This gene encodes for the protein collagen alpha-1(V) chain, which is found in ligaments, tendons, and other tissues containing type I collagen. The COL5A1 gene has been associated with both endurance running performance and sit-reach range of motion flexibility test.

Uncoupling proteins (UCPs) play a role in energy expenditure, thermogenesis (production of body heat), regulation of free fatty acids, and reduction of reactive oxygen species (buildup of such molecules can be harmful). The UCP3 gene encodes for a protein (mitochondrial uncoupling protein 3 - UCP3), which is selectively expressed in skeletal muscles. UCP3 protein is involved in regulating energy metabolism, weight control, and in modulating the use of fat and glucose for energy generation. A variation in the UCP3 gene has been shown to be associated with endurance athletes.

The AMPD1 gene plays a key role in the production of molecules that muscle cells can use for energy generation during physical activities.

HIF1A can influence response to hypoxia (deprivation of adequate oxygen supply) and oxygen uptake of cells by activating genes that affect the formation of red blood cells and blood vessels. It mediates the adaptation of skeletal muscles to endurance training.

Certain variations of the AGTR2 gene are associated with an increased proportion of slow-twitch muscle fiber which is related to endurance activities like long-distance running. Therefore, this gene is responsible for determining the endurance athlete status and aerobic performance.

This gene encodes for the protein Aquaporin 1. AQP1 facilitates the transfer of water from the blood into the muscle and promotes water reabsorption. Regulation of water flow across cell membranes is essential for supporting inter- and intracellular fluid balance, which is critical for health and exercise performance. AQP1 functions are vital during exercise and have a profound influence on endurance running performance.

The GNB3 gene encodes for the Gβ3 subunit of G proteins. It has been suggested that a variation in this gene is associated with enhanced G protein activation and G proteins are believed to be influenced by aerobic exercise.

This gene encodes for the protein collagen alpha-1(VI) chain. Type VI collagen is located in the space surrounding cells that make up the muscles used for movement (skeletal muscle cells) and cells that make up connective tissue, which provides strength and flexibility to structures throughout the body, including skin and joints. Collagen VI regulates the formation of fine fibrils present in collagen fibers.

The EPAS1 gene gives instructions for making a protein; which is one part (subunit) of a larger protein complex, playing a critical role in the body's ability to adapt to changing oxygen levels. This gene enables activities that favor the delivery of oxygen to the tissues during endurance exercises thus influencing the performance.

The NFIA-AS2 gene encodes for a long non-coding RNA which is suggested to play a role in regulating the expression of another gene which eventually influences erythropoiesis (production of red blood cells) and granulopoiesis (production of granulocytes which is a type of white blood cell). Variations of this gene, which influences erythropoiesis, plays a role in an individual’s ability to reach high levels in endurance activities.

The PPARGC1B gene encodes for a protein [peroxisome proliferator-activated receptor gamma, coactivator 1 beta (PGC1β)]. PPARGC1B along with the PPARGC1A gene play key roles in regulating adipogenesis (formation of fat cells), insulin signaling, lipolysis (the breakdown of fat), mitochondrial biogenesis (production of new mitochondria), angiogenesis (formation of new blood vessels), and hepatic gluconeogenesis (production of glucose by the liver). Variations in the PPARGC1B and PPARGC1A genes have been reported to influence muscle morphology, oxygen uptake, power output, and endurance performance, which can be associated with elite athletic performance.

The RBFOX1 gene encodes for a protein (RNA-binding protein, fox-1 homolog 1), which is key for regulating gene expression. This protein can influence muscle differentiation. A variation of the RBFOX1 gene has been associated with favorable muscle function in endurance athletes; this variation has been shown to be over-represented in endurance athletes when compared with power athletes.

The SLC2A4 gene encodes for a protein [solute carrier family 2 (facilitated glucose transporter), member 4, also known as a GLUT4], which plays an important role in the regulation of glucose metabolism by facilitating glucose uptake by muscles cells. this is required for energy production during endurance activities.

Mitochondria is essential for energy production, which is crucial for performing physical activities/exercises. Therefore, maintaining an optimum level of mitochondrial DNA and the expression of its genes are significant for energy supply. The TFAM gene encodes for a protein (mitochondrial transcription factor A), which is required for the expression of mitochondrial DNA and the protection of cells against oxidative stress. It has been noted that physical, aerobic activities tend to increase the expression of TFAM and subsequently, the number of mitochondrial DNA. Studies have found an association between a variation of this gene and physical performance in athletes.

The TSHR gene encodes for a protein that influences the production of thyroid hormones and regulates thyroid cell metabolism. The thyroid hormones have an effect on skeletal muscle tissue. A variation of the TSHR gene is associated with its higher expression, which in turn may result in increased angiogenesis (formation of new blood vessels) and/or the metabolic rate, which are factors that have a direct influence on aerobic performance.