Physical activity energy expenditure and cardiometabolic health in three rural Kenyan populations.

OBJECTIVES: Physical activity is beneficial for metabolic health but the extent to which this may differ by ethnicity is still unclear. Here, the objective was to characterize the association between physical activity energy expenditure (PAEE) and cardiometabolic risk among the Luo, Kamba, and Maasai ethnic groups of rural Kenya. METHODS: In a cross-sectional study of 1084 rural Kenyans, free-living PAEE was objectively measured using individually-calibrated heart rate and movement sensing. A clustered metabolic syndrome risk score (zMS) was developed by averaging the sex-specific z-scores of five risk components measuring central adiposity, blood pressure, lipid levels, glucose tolerance, and insulin resistance. RESULTS: zMS was 0.08 (-0.09; -0.06) SD lower for every 10 kJ/kg/day difference in PAEE after adjustment for age and sex; this association was modified by ethnicity (interaction with PAEE P < 0.05). When adjusted for adiposity, each 10 kJ/kg/day difference in PAEE was predicted to lower zMS by 0.04 (-0.05, -0.03) SD, without evidence of interaction by ethnicity. The Maasai were predicted to have higher cardiometabolic risk than the Kamba and Luo at every quintile of PAEE, with a strong dose-dependent decreasing trend among all ethnicities. CONCLUSION: Free-living PAEE is strongly inversely associated with cardiometabolic risk in rural Kenyans. Differences between ethnic groups in this association were observed but were explained by differences in central adiposity. Therefore, targeted interventions to increase PAEE are more likely to be effective in subgroups with high central adiposity, such as Maasai with low levels of PAEE.

Dietary patterns, food and macronutrient intakes among adults in three ethnic groups in rural Kenya.

OBJECTIVE: To compare dietary patterns and food and macronutrient intakes among adults in three ethnic groups in rural Kenya. DESIGN: In the present cross-sectional study, dietary intake was estimated in adult volunteers using two non-consecutive interactive 24 h recalls. Dietary patterns were assessed from the number of meals and snacks per day and from the food items and major food groups registered, and their contribution to energy intake (EI) was calculated. Anthropometric values were measured and sociodemographic data obtained using a questionnaire. SETTING: A cross-sectional study was conducted in the Bondo, Kitui and Transmara districts of rural Kenya. A high prevalence of food insecurity in Kenya underlines the importance of describing the dietary patterns and intakes in different Kenyan ethnic groups. SUBJECTS: A total of 1163 (61 % women) adult Luo, Kamba and Maasai, with a mean age of 38·6 (range: 18-68) years, volunteered to participate. RESULTS: Dietary patterns and food groups contributing to EI differed significantly among the ethnic groups. Mean EI ranged from 5·8 to 8·6 MJ/d among women and from 7·2 to 10·5 MJ/d among men, with carbohydrates contributing between 55·7 % and 74·2 % and fat contributing between 14·5 % and 30·2 % of total EI. Mean protein intake ranged from 0·72 to 1·3 g/kg per d, and EI:BMR ratio ranged between 1·1 and 1·6 in both sexes, and was highest among the Luo. Prevalence of underweight (BMI < 18·5 kg/m2) was 13·7 %, 20·5 % and 24·2 % in the Luo, Kamba and Maasai, respectively. CONCLUSIONS: The degree of food insecurity measured as a degree of undernutrition and as dietary patterns differed considerably among the ethnic groups. The Maasai and Kamba in particular were exposed to food insecurity.

The ACTN3 R577X polymorphism in East and West African 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 x 10(6) Markov chain steps, and 1 x 10(5) dememorization steps. RESULTS: The frequency of the X allele was extremely low among Kenyans and Nigerians (approximately 1% homozygosity) and higher in Ethiopians (approximately 11% 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 alpha-actinin-3 deficiency is not a major influence on performance in African athletes.

Demographic characteristics of elite Kenyan endurance runners.

Kenyan athletes have dominated international distance running in recent years. Explanations for their success include favourable physiological characteristics, which could include favourable genetic endowment, and advantageous environmental conditions. The aim of this study was to compare the demographic characteristics of elite Kenyan runners with those of the general Kenyan population. Questionnaires, administered to 404 elite Kenyan runners specializing in distances ranging from the 800 m to the marathon and 87 Kenyan controls, obtained information on place of birth, language, and distance and method of travel to school. Athletes were separated into two groups according to athletic success: those who competed in international competition and those who competed in national competition. The 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 (controls 20%, national athletes 65%, international athletes 81%), belonged to the Kalenjin ethnic group (controls 8%, national athletes 49%, international athletes 76%) and Nandi sub-tribe (controls 5%, national athletes 25%, international athletes 44%), and spoke languages of Nilotic origin (controls 21%, national athletes 60%, international athletes 79%). A higher proportion of all athletes ran to school each day (controls 22%, national athletes 73%, international athletes 81%) and covered greater distances. In conclusion, Kenyan runners are from a distinctive environmental background in terms of geographical distribution, ethnicity and travelled further to school, mostly by running. These findings highlight the importance of environmental and social factors in the success of Kenyan runners.