Diet, hydration, lifestyle and training practices of elite Kenyan endurance runners

Since the emergence of Kenyan endurance runners on the world stage at the 1968 Mexico Olympics, where they won 8 medals ranging from 400 m relay to the 10 000 m, Kenyan success has grown year on year. The staggering success of a country that compromises just 0.5 % of the world population has triggered a number of explanations. Heavily cited explanations are genetic superiority and environmental factors. Despite a number of investigations, genetic superiority remains to be determined, what is clear though is that the environmental factors that interact with each genetic element leading to world-class performance are particularly important. Aims and objectives: Given the importance environmental factors may have on the process leading to world class performance, the main aims of the following research were: 1) to determine the composition of elite Kenyan endurance runners diet and assess their energy balance status prior to major competition using "gold standard" methods; 2) to establish lifestyle practices of elite Kenyan endurance runners prior to major competition that will allow an insight in to the preparation of some of the best athletes in the world; 3) to ascertain the hydration status of elite Kenyan endurance runners during an important training period and directly compare these results to traditional paradigms and current thinking on optimal fluid intake for superior endurance running performance; 4) to investigate the training process leading to world class performance by quantifying training load in the lead up to major competition; 5) to determine the fluid intake behaviours of the world's best marathon runners during racing. This will allow an insight into current practices of elite runners that will act as a benchmark and comparison of current fluid intake guidelines; and 6) to validate and combine existing technologies of heart rate and accelerometry for quantifying energy expenditure during free living conditions. Methods: Chapters 2 and 3 detail extensively the diet, hydration, lifestyle and training practices of a group of highly successful elite Kenyan endurance runners during important training periods based at a high altitude camp in Kenya. Chapter 4 explores the significance of the hydration practices reported in Chapters 2 and 3 (i.e., ad libitum fluid intake) have on elite marathon running performance and the wider implications for fluid intake recommendations for elite marathon running. Chapter 5 investigates novel technology (i.e., the combined use of accelerometry and heart rate) that may further enhance our understanding of the physical activity patterns and training practices of elite Kenyan endurance runners on a day-to-day basis. Results and discussion: Chapter 2 reported elite Kenyan endurance runners are in negative energy balance prior to major competition as assessed by the gold standard doubly labeled water method (Energy intake: 13.2 +/- 1.3 MJ/d: vs. Energy expenditure: 14.6 +/- 1.0 MJ/d; p lt; 0.005). Considering the relatively high carbohydrate content of their diet (e.g., 67.3 +/- 7.8 %, 9.8 g/kg/bm) it is hypothesised the caloric deficit may not have a direct impact on their training performance. In fact the performance implications of reducing body mass as a result of energy deficiency is that the athletes will be lighter for competition and may thus be at an advantage as the energy cost per unit distance increases in direct proportion to the added load expressed as a percentage of body mass. Measured physical activity patterns (i.e., Physical Activity Ratio (PAR) and accelerometry) of elite Kenyan endurance runners strongly suggest rest between running training sessions is an important lifestyle factor as it was found time spent relaxing, in light activity, slow running (8.0-13.6 km/h), moderate running (13.7-17.3 km/h), and fast running (> 17.4 km/h) as estimated using the PAR method was 82 +/- 6 %, 8 +/- 6 %, 3 +/- 1 %, 5 +/- 1 %, 2 +/- 1 %, respectively. The reported time spent in light, moderate, hard and very hard activity as determined by accelerometry was 82 +/- 3 %, 11 +/- 2 %, 6 +/- 3 %, and 1 +/- 1 % respectively. A further striking finding in Chapter 2 was the relatively low daily fluid intake that consisted of primarily water (0.9 +/- 0.5 L/d) and milky tea (0.9 +/- 0.3 L/d). Chapter 3 found athletes remained hydrated day-to-day drinking ad libitum despite this relatively low daily fluid intake that corroborated prevailing fluid intake recommendations. This was evidenced by mean total body water and pre training body mass being maintained day-to-day throughout the recording period (p = 0.194 and p = 0.302, respectively). Furthermore, there was no significant difference between the osmolality of the morning urine sample and the evening sample (p = 0.685). It was also found that athletes remained in electrolyte balance (Na+ intake: 3245 +/- 901 vs. Na+ loss: 3254 +/- 1070 mg/d; p = 0.975) day-to-day thus negating the need for further supplementation. The training load analysis supports the contention that elite endurance athletes spend the majority of their training time at low intensity (26 % of total weekly training time spent > 80 % heart rate peak) with periods of high intensity work interspersed (e.g., twice weekly track session). Chapter 4 reported prevailing fluid intake recommendations that recommend a specific fluid intake rate (i.e., 0.4-0.8 L/h) are insufficient for elite marathon running evidenced by mathematical modelling and video analysis of drinking behaviours of the winners of a major city marathon. As a direct result of these findings it is proposed the best strategy for competitive marathon running in temperate conditions is to drink ad libitum as long as body mass loss is kept within acceptable limits, possibly < 3 %. The ad libitum drinking pattern supports observations of the elite Kenyan endurance runners reported in Chapter 2 and 3. Chapter 5 is the first study to report an accelerometer that can operate up to and including 20 km/h. It was also found the combined use of tri-axial accelerometry and heart rate (r2 = 0.80) predict VO2 better during fast running than either predictor alone (heart rate: r2 = 0.59; accelerometry: r2 = 0.76) and that subject's individually calibrated data further improves VO2 estimation (r2 = 0.99). Conclusions: The main findings of the research do not point to one single explanation for the Kenyan running phenomenon. The results suggest the explanation is likely to be complex in origin and that many individual factors may well aggregate to produce world class performance. It is proposed that future studies should focus on developing combined technologies such as accelerometery and heart rate in order to better understand physical activity patterns and energy expenditure of elite Kenyan endurance runners on a day-to-day basis over an extended period of time that incorporates multiple training cycles. It is also suggested that similar studies to those presented here in Chapters 2-3 are conducted in Ethiopia due to their recent staggering success in endurance running

Evidence of negative energy balance using doubly labelled water in elite Kenyan endurance runners prior to competition

Previous studies have found Kenyan endurance runners to be in negative energy balance during training and prior to competition. The aim of the present study was to assess energy balance in nine elite Kenyan endurance runners during heavy training. Energy intake and expenditure were determined over 7d using weighed dietary intake and doubly labelled water, respectively. Athletes were on average in negative energy balance (mean energy intake 13 241 (SD 1330) kJ/d v. mean energy expenditure 14 611 (SD 1043) kJ/d; P=0·046), although there was no loss in body mass (mean 56·0 (SD 3·4) kg v. 55·7 (SD 3·6) kg; P=0·285). The calculation of underreporting was 13; (range −24 to +9%) and almost entirely accounted for by undereating (9% (range −55 to +39%)) as opposed to a lack of significant underrecording (i.e. total water intake was no different from water loss (mean 4·2 (SD 0·6) l/d v. 4·5 (SD 0·8) l/d; P=0·496)). Fluid intake was modest and consisted mainly of water (0·9 (SD 0·5) l/d) and milky tea (0·9 (SD 0·3) l/d). The diet was high in carbohydrate (67·3 (SD 7·8) %) and sufficient in protein (15·3 (SD 4·0) %) and fat (17·4 (SD 3·9) %). These results confirm previous observations that Kenyan runners are in negative energy balance during periods of intense training. A negative energy balance would result in a reduction in body mass, which, when combined with a high carbohydrate diet, would have the potential in the short term to enhance endurance running performance by reducing the energy cost of runnin

Greater male variability in daily energy expenditure develops through puberty

The authors also gratefully acknowledge funding from the Chinese Academy of Sciences (grant no. CAS153E11KYSB20190045) to J.R.S. and the US National Science Foundation (grant no. BCS-1824466) awarded to H.P. Acknowledgements Yvonne Schönbeck provided important information about morphometric measurements for Dutch children. A chat over dinner with Karsten Koehler, Eimear Dolan and Danny Longman brought up a number of thoughts that influenced this manuscript. The DLW database, which can be found at https://doublylabelled-waterdatabase.iaea.org/home, is hosted by the IAEA and generously supported by Taiyo Nippon Sanso and SERCON. We are grateful to the IAEA and these companies for their support and especially to Takashi Oono for his tremendous efforts at fundraising on our behalf.Peer reviewedPublisher PD

Total energy expenditure is repeatable in adults but not associated with short-term changes in body composition

Low total energy expenditure (TEE, MJ/d) has been a hypothesized risk factor for weight gain, but repeatability of TEE, a critical variable in longitudinal studies of energy balance, is understudied. We examine repeated doubly labeled water (DLW) measurements of TEE in 348 adults and 47 children from the IAEA DLW Database (mean ± SD time interval: 1.9 ± 2.9 y) to assess repeatability of TEE, and to examine if TEE adjusted for age, sex, fat-free mass, and fat mass is associated with changes in weight or body composition. Here, we report that repeatability of TEE is high for adults, but not children. Bivariate Bayesian mixed models show no among or within-individual correlation between body composition (fat mass or percentage) and unadjusted TEE in adults. For adults aged 20-60 y (N = 267; time interval: 7.4 ± 12.2 weeks), increases in adjusted TEE are associated with weight gain but not with changes in body composition; results are similar for subjects with intervals >4 weeks (N = 53; 29.1 ± 12.8 weeks). This suggests low TEE is not a risk factor for, and high TEE is not protective against, weight or body fat gain over the time intervals tested

Variability in energy expenditure is much greater in males than females

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Variability in energy expenditure is much greater in males than females

In mammals, trait variation is often reported to be greater among males than females. However, to date, mainly only morphological traits have been studied. Energy expenditure represents the metabolic costs of multiple physical, physiological, and behavioral traits. Energy expenditure could exhibit particularly high greater male variation through a cumulative effect if those traits mostly exhibit greater male variation, or a lack of greater male variation if many of them do not. Sex differences in energy expenditure variation have been little explored. We analyzed a large database on energy expenditure in adult humans (1494 males and 3108 females) to investigate whether humans have evolved sex differences in the degree of interindividual variation in energy expenditure. We found that, even when statistically comparing males and females of the same age, height, and body composition, there is much more variation in total, activity, and basal energy expenditure among males. However, with aging, variation in total energy expenditure decreases, and because this happens more rapidly in males, the magnitude of greater male variation, though still large, is attenuated in older age groups. Considerably greater male variation in both total and activity energy expenditure could be explained by greater male variation in levels of daily activity. The considerably greater male variation in basal energy expenditure is remarkable and may be explained, at least in part, by greater male variation in the size of energy-demanding organs. If energy expenditure is a trait that is of indirect interest to females when choosing a sexual partner, this would suggest that energy expenditure is under sexual selection. However, we present a novel energetics model demonstrating that it is also possible that females have been under stabilizing selection pressure for an intermediate basal energy expenditure to maximize energy available for reproduction. (C) 2022 The Author(s). Published by Elsevier Ltd.Peer reviewe

Energy compensation and adiposity in humans

Acknowledgments The DLW database, which can be found at https://doubly-labelled-water-database.iaea.org/home, is hosted by the IAEA and generously supported by Taiyo Nippon Sanso and SERCON. We are grateful to the IAEA and these companies for their support and especially to Takashi Oono for his tremendous efforts at fundraising on our behalf. The authors also gratefully acknowledge funding from the Chinese Academy of Sciences (CAS 153E11KYSB20190045) to J.R.S. and the US National Science Foundation (BCS-1824466) awarded to H.P. The funders played no role in the content of this manuscript. We are grateful for the data submission of David Ludwig and Cara Ebbeling, and for the analysis by Steve Heymsfield of his own data indicating no change in FFM hydration with age in adults.Peer reviewedPublisher PD

Variation in human water turnover associated with environmental and lifestyle factors

Water is essential for survival, but one in three individuals worldwide (2.2 billion people) lacks access to safe drinking water. Water intake requirements largely reflect water turnover (WT), the water used by the body each day. We investigated the determinants of human WT in 5604 people from the ages of 8 days to 96 years from 23 countries using isotope-tracking (2H) methods. Age, body size, and composition were significantly associated with WT, as were physical activity, athletic status, pregnancy, socioeconomic status, and environmental characteristics (latitude, altitude, air temperature, and humidity). People who lived in countries with a low human development index (HDI) had higher WT than people in high-HDI countries. On the basis of this extensive dataset, we provide equations to predict human WT in relation to anthropometric, economic, and environmental factors.acceptedVersio

Greater male variability in daily energy expenditure develops through puberty

There is considerably greater variation in metabolic rates between men than between women, in terms of basal, activity and total (daily) energy expenditure (EE). One possible explanation is that EE is associated with male sexual characteristics (which are known to vary more than other traits) such as musculature and athletic capacity. Such traits might be predicted to be most prominent during periods of adolescence and young adulthood, when sexual behaviour develops and peaks. We tested this hypothesis on a large dataset by comparing the amount of male variation and female variation in total EE, activity EE and basal EE, at different life stages, along with several morphological traits: height, fat free mass and fat mass. Total EE, and to some degree also activity EE, exhibit considerable greater male variation (GMV) in young adults, and then a decrease in the degree of GMV in progressively older individuals. Arguably, basal EE, and also morphometrics, do not exhibit this pattern. These findings suggest that single male sexual characteristics may not exhibit peak GMV in young adulthood, however total and perhaps also activity EE, associated with many morphological and physiological traits combined, do exhibit GMV most prominently during the reproductive life stages