Nature
The genetic model argues that a predetermined set of genetic traits predicts athletic potential and success. These physical traits are polygenic, or coded by many genes, producing the ultimate elite phenotype (Tucker & Collins, 2012). The four most influential traits include: gender, height, skeletal muscle composition, and VO2max. The most obvious influence on athletic performance is the drastic segregation of male and female performances; this is proof of genetic predisposition to athletic potential. Height is developed by both nature and nurture (nutrition), and is very predictive of sport-specific success—or example, the height required for basketball players is not conducive to long-distance running.
Studies have found a number of VO2max genes in untrained individuals, which are inherently genetic, and also genes activated by training, which are environmentally influenced (Tucker & Collins, 2012). VO2max is a strong predictor of maximal aerobic capacity and, thus, performance in endurance-based events. Being genetically gifted with a superior aerobic capacity automatically places the athlete in an advantageous position for accelerated graduation to the elite level. Skeletal muscle properties are subject to similar genetic and environmental influences. Hence, an athlete born with greater strength capacity in their musculature will have an easier time transitioning into strength-based sports, such as football or wrestling.
The dominance of East African runners in the middle- and long-distance events is well-known, especially in the last decade where 85% of the Top 20 ranks in the world have come from this region (Vancini et al., 2014). These runners are primarily of Kenyan and Ethiopian descent and classically possess high VO2 max, hemoglobin, hematocrit, tolerance to altitude, bland diets of rice and beans, optimal running economy, and optimal muscle fiber type composition (Wilber & Pitsiladis, 2012). Much research has explored the possibility that genetic factors have yielded an advantage in this particular population, especially genes responsible for anthropometric, cardiovascular, and muscular adaptations to training (Vancini et al., 2014).
The first studies performed on this group focused on mitochondrial DNA (mtDNA) variation, which is an easy way to phylogenize specific haplotypes, or sets of inheritance patterns, as they were passed through the maternal genetic line. If a haplotype is localized to one area of origin or one people group, it may be considered a strong indicator of a particular phenotype. It turned out that the gene pools between Kenyan and Ethiopian runners varied so greatly that the support for mtDNA’s role in athletic giftedness was inconclusive (Wilber & Pitsiladis, 2012).
Two genes, in particular, have been more recently theorized to produce high performance phenotypes. The first is angiotensin converting enzyme (ACE); an insertion polymorphism on this gene results in a genetic downregulation of ACE, resulting in greater cardiorespiratory fitness and tolerance to altitude/oxygen-deprivation (Vancini et al., 2014). Interestingly, a deletion of the same gene results in ACE upregulation and, thus, increases musculoskeletal fitness ideal for power competitions. The second gene is alpha-actin-3 (ACTN3), which can polymorph into the R577X variant; the XX allele on this gene is found with higher frequency in endurance athletes and does not result in the expression of ACTN3.
None of the current evidence supports a conclusive explanation for either of these genes being solely responsible for East African success. While it is unlikely that a single nucleotide polymorphism (SNP), such as the ones mentioned above, is the determinant of athletic giftedness, there is much promise for the rapidly expanding field of genomics to produce answers in the near future.
Nurture
There are also environmental factors that may play a role in the success of middle- and long-distance East African runners. Physiological adaptations, diet and nutrition, and socioeconomic factors are all worth equal consideration in the development of these superior athletes. Certain physiological parameters have measured higher in this population, such as total hemoglobin, VO2 max, and hematocrit; this is attributed to the altitude at which these Africans live and train, which falls in the range of 2,000-2,500 meters (6,500-8,200 feet) (Wilber & Pitsiladis, 2012).
Exceptional cardiovascular development may be a result of 86% of Kenyan and 68% of Ethiopian international elites using running as a primary means of transportation to school as children (Wilber & Pitsiladis, 2012). VO2 max, a measure of maximal oxygen uptake, did not appear significantly dissimilar than other elite athletes of different nationalities despite their gap in performance, indicating that there is more than VO2 max that plays into the Africans’ success.
