The African running phenomenon: the role of genetics, nutrition and demographic factors in explaining the success of East African runners in international distance running
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Date
2006
Authors
Onywera, V.O.
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University
Abstract
Kenyan athletes have dominated international distance running in recent years.
Explanations for their success include favourable physiological characteristics, which
may include favourable genetic endowment and advantageous environmental conditions.
The purpose of this study was to analyse the genetic, nutritional and demographic
characteristics of elite Kenyan endurance runners. Questionnaires were administered to
elite Kenyan runners specializing in distances ranging from the 800 m to the marathon
and Kenyan control subjects (C)(n=87). The questionnaires sought information on place
of birth, language, motivation for becoming athletes, distance and method of travel to
school. Diet logbooks were used to assess the athletes' dietary habits during training. The
training regime of the runners was monitored using a training diary. Athletes were
separated into two groups according to athletic success: International level athletes
(I)(n=97) and national level athletes (N)(n=307). DNA samples were collected from the
subjects using buccal swabs. Both qualitative and quantitative research designs were used
in this study. Data were presented in bar charts, pie charts, line graphs and tables. Chisquares
were used to establish any significant differences within and between the groups.
The level of significance was set at 0.05. Athletes differed from controls in regional
distribution, language, and distance and method of travel to school; athletes also differed
from each other with the exception of method of travel to school. Most national and
international athletes came from the Rift Valley province (C: 20 %, N: 65 %, I: 82 %) (C:
n=17: N: n=200: I: n=80), of those who belonged to the Kalenjin ethnic group (C: 8 %,
N: 49 %, I: 76 %) (C: n=7: N: n=150:l: n=74) and Nandi sub-tribe (C: 5 %, N: 25 %, I:
45 %) (C: n=4: N: n=77: I: n=44) and who spoke languages of Nil otic origin (C: 20 %, N:
59 %, I: 80 %) (C: n=17: N: n=181: I: n=78). A higher proportion of all athletes ran to
school each day (C: 22 %, N: 73 %, I: 83 %) and covered greater distances. Kenyan
runners are from a distinctive environmental background in terms of geographical
distribution, ethnicity, and also having travelled further to school, mostly by running.
Estimated energy intake (El: 2987 ±293 kcal; mean ±standard deviation) was lower than
energy expenditure (EE: 3605 ±119 kcal; p <0.001) and body mass (BM: 58.9 ±2.7 kg
vs.58.3 ±2.6 kg; P <0.001) was reduced over the 7-d intense training period. Diet was
high in carbohydrate (76.5%, 10.4 g/kg BM per day) and low in fat (13.4%). Protein
intake (10.1%; 1.3 g/kg BM per day) matched recommendations for protein intake. Fluid
intake was modest and mainly in the form of water (1113 ±269 mL;O. 34 ±0.16 ml/kcal)
and tea (1243 ±348 ml). Although the diet met most recommendations for endurance
athletes for macronutrient intake, it remains to be determined if modifying energy
balance and fluid intake will enhance the performance of elite Kenyan runners. IID
genotype was not associated with elite endurance athlete status (df= 4, i=3.5, P = 0.47)
with no over-representation of the I allele among N (0.42) or I (0.39) athletes relative to
controls (0.38). The absence of an association between the IID polymorphism with elite
Kenyan athlete status suggests that the ACE gene does not contribute significantly to the
phenomenal success of Kenyan endurance runners in international distance running.
These results do not support the hypothesis that ACE gene variation is associated with
elite endurance performance.
Description
A thesis submitted in fulfillment of the requirements for the degree of doctor of philosophy in the school of Health Science of Kenyatta University. 2006, GV 1062.O6