Elite endurance athletes are of a distinct environmental background in terms of geographical distribution, ethnicity, and also having generally traveled farther to school, often by running. These findings may reflect both environmental and genetic influences on athletic success in Ethiopian endurance athletes.

. Purpose: To determine the frequency of the ACTN3 R577X polymorphism (functional R allele and nonfunctional X allele) in a variety of African populations and to examine its influence on the success of elite East African endurance runners and West African sprinters. Methods: The R577X polymorphism was genotyped in 198 Ethiopian controls and 76 elite Ethiopian endurance athletes, 158 Kenyan controls and 284 elite Kenyan endurance runners, and 60 Nigerian controls and 62 elite Nigerian power athletes. Statistical analyses were performed by exact tests of population differentiation, using Arlequin, version 3. Analyses were carried out using 1 Â 10 6 Markov chain steps, and 1 Â 10 5 dememorization steps. Results: The frequency of the X allele was extremely low among Kenyans and Nigerians (È1% homozygosity) and higher in Ethiopians (È11% homozygosity). The low baseline frequencies of the three populations tested mean that any associations with sprint performance would likely be obscured. In Ethiopians, where baseline levels of 577XX were about 11%, there was no increased frequency in the endurance athletes. Conclusion: Our data suggest that >-actinin-3 deficiency is not a major influence on performance in African athletes. Key Words: GENETICS, ACTININ-3, AFRICA, RUNNERS, ATHLETIC PERFORMANCE T he actin-binding protein >-actinin-3, encoded by the ACTN3 gene, is a highly conserved component of the contractile machinery in fast skeletal muscle fibers in mammals (7). Homozygosity for a common nonsense polymorphism, R577X, results in complete deficiency of >-actinin-3 in about 16% of the global human population (11). We have previously demonstrated a strong association between the R577X polymorphism and elite athlete status in Australian Caucasian populations, with the >-actinin-3-deficient XX genotype being present at a lower frequency in sprint/power athletes, and at slightly higher frequency in elite female endurance athletes, relative to controls (18). The negative association of the XX genotype with sprint performance was subsequently replicated in a cohort of Finnish elite track and field athletes (10). The possible positive association of XX with endurance performance remains intriguing but uncertain, with two recent smaller studies comparing R577X genotype frequencies between 50 elite endurance cyclists, 52 elite endurance runners, and 123 controls from Spain (6), and 42 male rowers and 102 male controls from Italy (13), finding no significant differences in R577X genotype frequencies between control and athlete groups. R577X genotype has also been associated with muscle function parameters in several large nonathlete cohorts. An analysis of 355 females demonstrated an association between the XX genotype and lower baseline muscle strength (1), whereas a study of older individuals found that R577X genotype influences the response of the quadriceps muscle to strength training (2). In a large cohort of Greek adolescents, the XX genotype was associated with significantly slower performance in a 40-m sprint (9). These ...

BackgroundExplanations for the phenomenal success of East African distance runners include unique dietary practices. The aim of the present study was to assess the food and macronutrient intake of elite Ethiopian distance runners during a period of high intensity exercise training at altitude and prior to major competition.MethodsThe dietary intake of 10 highly-trained Ethiopian long distance runners, living and training at high altitude (approximately 2400 m above sea level) was assessed during a 7 day period of intense training prior to competition using the standard weighed intake method. Training was also assessed using an activity/training diary.ResultsBody mass was stable (i.e., was well maintained) over the assessment period (pre: 56.7 ± 4.3 kg vs. post: 56.6 ± 4.2 kg, P = 0.54; mean ± SD). The diet comprised of 13375 ± 1378 kJ and was high in carbohydrate (64.3 ± 2.6%, 545 ± 49 g, 9.7 ± 0.9 g/kg). Fat and protein intake was 23.3 ± 2.1% (83 ± 14 g) and 12.4 ± 0.6% (99 ± 13 g, 1.8 ± 0.2 g/kg), respectively. Fluid intake comprised mainly of water (1751 ± 583 mL), while no fluids were consumed before or during training with only modest amounts being consumed following training.ConclusionsSimilar to previous studies in elite Kenyan distance runners, the diet of these elite Ethiopian distance runners met most recommendations of endurance athletes for macronutrient intake but not for fluid intake.

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