A primary challenge when attempting to describe the influence of genetic factors on athletic performance is its multifactorial nature. Every sport has unique physical requirements and these requirements can be dramatically different between sports. Therefore, any study of the genetic influence on performance must consider the performance components most appropriate for the sport of interest.
Considering the number of body systems that must interact (musculoskeletal, cardiovascular, respiratory, nervous, etc.), athletic performance is one of the most complex human traits. Perhaps the first noticeable difference between athletes of different specialties is in body morphology (i.e., height and body composition), with specific body types naturally suited to specific sports. Beyond body morphology, endurance, strength, and power are primary factors underlying athletic performance.
Aerobic endurance is the ability to sustain an aerobic effort over time, such as distance running or cycling. At the most basic level, aerobic endurance requires the ability of the cardiovascular system to deliver oxygen to the working muscles and the ability of the muscles to utilize that oxygen. The most common quantification of endurance is the maximal rate of oxygen uptake (VO2max). However, VO2max does not perfectly correlate with endurance performance (e.g. marathon running), as other factors such as economy and ventilatory threshold also influence performance.
Muscular strength is the ability of the muscle to generate force. Muscular strength is generally quantified by the one repetition maximum. Muscle power is the interaction between the force and velocity of a muscle contraction (e.g. an explosive movement such as vertical jump). Muscle strength and power are critical in athletic events such as sprinting, jumping, and weightlifting.
Additional components of athletic performance include cognitive factors and injury susceptibility. It is critical to remember that the environment (e.g., training, nutrition) also influences many of these traits. An individual’s “trainability,” or response to exercise training, is also partially dependent on genetic factors, as recently reviewed by Bouchard