Scientists find 13 candidate genes associated with fitness outcomes

• Researchers from Cambridge University published a meta-analysis in PLOS ONETrusted Source identifying 13 candidate genes associated with fitness outcomes in previously untrained people.
• Genetic influences accounted for 72% of the difference in the results of those in the strength training group.
• Genetic factors had less effect on the outcomes in the aerobic (44%) and anaerobic power groups (10%).
• Further research is necessary to determine the exact roles of fitness genes and how best to tailor exercise training according to genetic makeup.

Physical activity is essentialTrusted Source for maintaining health, reducing chronic diseases, and preventing premature death. The 2018 physical activity guidelines for AmericansTrusted Source recommend a combination of moderate intensity and vigorous intensity aerobic exercise alongside muscle-strengthening activities involving the major muscle groups.

The adviceTrusted Source is for adults to do 150–300 minutes of moderate intensity aerobic activity, 75–150 minutes of vigorous intensity aerobic activity, or an equivalent mix. They can spread this activity throughout the week and should also engage in strength training on at least 2 days of the week to reap additional health benefits.

The three components necessary to determine health-related fitness are cardiovascular fitness, muscle strength, and anaerobic power. Cardiovascular or cardiorespiratory fitnessTrusted Source measures how efficiently the respiratory and circulatory systems supply oxygen to the skeletal muscle for energy production during physical activity.

The maximum oxygen uptake (VO2 max) test is one way to determine cardiorespiratory fitness. The VO2 max test measures the body’s maximum oxygen consumption capacity during a vigorous intensity activity, such as running on a treadmill.

A higher VO2 max indicates an improved ability to supply and utilize oxygen and maintain aerobic activities at an increased intensity for extended periods. Low cardiorespiratory fitness is a predictor of cardiovascular disease and death from all causes in adults.

Muscular strength is the body’s capability to exert a sufficient force against external resistance to perform tasks and maintain mobility.

An anaerobic activity is one that involves the breakdown of glucose for energy without using oxygen. Anaerobic power measures the body’s ability to move with the greatest intensity in a short period.

Increasing cardiorespiratory fitness, muscular strength, and anaerobic power may improve a person’s overall fitness level, but responsiveness to exercise training varies considerably among individuals.

Genetic differences

In a session at the 22nd Annual Congress of the European College of Sports Science, Dr. Bernd Wolfarth, professor in the Department of Sports Medicine at Humboldt University, Berlin, explains, “Environment is a major factor [for trainability], and nowadays, we know that about 25–40% of the variability of phenotype results from genes, and the other 60–75% is coming [from] environmental effects.”

Specific genes called candidate genesTrusted Source may predict successful responses to targeted types of exercise training. These genes may influence energy pathways, metabolism, storage, and cell growth in the body.

These findings led researchers from the Cambridge Centre for Sport and Exercise Sciences at Anglia Ruskin University, UK, to conduct a meta-analysis to identify the specific version, or allelesTrusted Source, of candidate genes related to the exercise response in untrained participants. The team analyzed strength, anaerobic power, and cardiopulmonary fitness.

Individuals inherit one allele of each gene from each parent. The individual is homozygous for the gene if both alleles are the same and heterozygous if the two alleles are different.

The study also assessed whether the identified genes and alleles contributed to differences in exercise training response among the participants. The researchers analyzed the results from 24 different studies with a total of 3,012 participants. Of the cohort, 1,512 participants were male, and 1,239 were female. The sex of the remaining 261 participants was not stated.

The mean age of the participants was 28 years. There were 89 groups: 43 aerobic, 29 strength, and 17 power. The researchers identified 13 candidate genes and alleles, of which nine, six, and four were associated with cardiorespiratory fitness, muscular strength, and anaerobic power, respectively.