diet intake and endurance performance in kenyan runners

7/24/2019 Diet Intake and Endurance Performance in Kenyan Runners

1/5

Diet intake and endurance

performance in Kenyan runners

Dirk L Christensen1,2,*1Department of Epidemiology, Institute of Public Health, University of Copenhagen,Blegdamsvej 3, Building 2, DK-2200 Copenhagen N, Denmark2Copenhagen Muscle Research Centre, Rigshospitalet (National University Hospital),Copenhagen, Denmark*Corresponding author: [email protected] Review Article

AbstractTraining and competing at elite as well as sub-elite level requires an optimal functioning of the body. This reviewlooks at the case of the Kenyan runners, who consume a relatively high-quality diet based on vegetable sources

with maize and kidney beans as the staple foods. The diet is high in carbohydrate and total protein, but low toborderline in a few essential amino acids. The timing of diet intake immediately after training sessions is opti-mal for skeletal muscle glycogen resynthesis that is enhanced without the help of insulin up to 60 min after cessa-tion of exercise. Whether the total energy intake of the Kenyan runners is adequate is debatable. However,chronic undernutrition is not possible for athletes who engage in daily high-quality and -quantity physical exercisethroughout most of the year. It is suggested that Kenyan runners participate in well-controlled, laboratory studiesto investigate the quality of local foods and performance, as well as possible physiological adaptation mechanismsamong athletes with a high habitual energy turnover.

Keywords: Kenya; runners; macronutrient intake; performance

Introduction

Training and competing at elite and even sub-elite levelin the middle and long distances (800 m to marathon)requires an optimal functioning of the body, whichrelies on a nutritionally adequate diet providing suffi-cient energy, as well as an adequate content of macro-and micronutrients. Until a few years ago, little wasknown about the dietary intake of Kenyan runnersdespite them having been a dominating force in inter-national athletics for several decades. Only anecdotal

information and no scientific data on this subject wereavailable until a decade ago, when Mukeshi andThairu1 evaluated the dietary intake of elite maleKenyan athletes including male long-distance runners.Unfortunately, the study was based on questionnairesonly. However, a substantial body of dietary investi-gations in general have been carried out in Kenya overthe past ,80 years24. These studies revealed severalcases of malnutrition especially proteinenergy andmicronutrient malnutrition indicating a very limitedavailability of high-quality food sources. This indicatespotential performance problems for Kenya-based

athletes in training and competition. Based on theabove, the present paper addresses the carbohydrate,protein and energy intakes of Kenyan runners to

investigate whether they are adequate and to elucidatesubsequent implications for physical performance.

Food and macronutrient intakes

The only investigation that has looked at the macronu-trient intakes of Kenyan runners in detail, including col-lection and analysis of food samples, showed that theirdiet was based on a relatively small range of food itemsfrom mainly vegetable sources5. The staple foods were

maize and kidney beans, both of which contributedessentially to protein intake. Furthermore, cabbage,curly kale, wheat bread, milk, coffee and meat werethe remaining sources of daily food intake5. This inves-tigation was carried out over a two-week period atMarakwet High School (formerly Marakwet SecondarySchool), a typical Kenyan boarding school situated inthe western highlands at 2600 m above sea level.The adolescent male student-runners participating inthe study (n 12) were all Kalenjin, a Nilotic sub-group, and the most successful ethnic group in runningfrom Kenya over time. All runners competed at the sub-

elite level in the middle and long distances. The energyintake of the runners was mainly derived from veg-etable sources, but surprisingly meat and milk

Equine and Comparative Exercise Physiology 1(4); 249253 DOI: 10.1079/ECEP200430

qCAB International 2004


2/5

consumption comprised only 10% of total energy intake(Table 1). Historically, the Nilotes have depended pri-marily on milk, but also on blood and meat as theirstaple foods. However, it is a misconception to regardNilotes as pure pastoralists since most of them havesupplemented their diet with grain foods, historicallyas well as presently6,7. This is especially true for theKalenjin8. Still, we expected milk intake to play amore prominent role in the diet of the runners atMarakwet High School. But it was only a few weeksprior to important competitions that they were sup-plied with extra milk. As it turned out, the studymade by our group showed that maize and kidneybeans alone made up 81% of the total energy intakeof the student-athletes at Marakwet High School.Furthermore, the energy distribution of their macronu-

trient intakes was 71% for carbohydrate, 15% for fatand 13% for protein5.

Carbohydrate intake, glycogen resynthesisand performance implications

In the literature there is an abundance of evidenceshowing that a high daily intake of carbohydrate isadvantageous in post-exercise recovery as well as inperformance (for recent reviews, see Burke et al.9,10).However, some authors have questioned the officialdietary guidelines11, stating that the recommendationfor carbohydrate intake (6070% of total energyintake) is not consumed by athletes in training andthat the carbohydrate intake of athletes has notincreased over the past 50 years12. This implies thatathletes do not need such high carbohydrate intakes.

While the statement is true for athletes in industrial-ized countries in general, at least the first part of thestatement is not true when it comes to athletes inthe developing world, as shown by studies carriedout among ultra-distance runners in Mexico13 andKenyan middle- and long-distance runners1,5. It is,however, important to emphasize that a high intakeof carbohydrate, expressed as a percentage of total

energy intake, is crucial only when the diet is low inenergy (such as shown in many studies on femaleendurance athletes) in order for the athlete to replen-ish his/her liver and skeletal muscle glycogen stores(for review, see Burke14). More important is a highcarbohydrate intake in relation to body weight, for

which there are guidelines for short-term/singleevents as well as for long-term or routine situ-ations15,16. The Kalenjin runners from our study hada daily carbohydrate consumption of 8.7 g kg21 body

weight, which is well above the 67 g kg21 bodyweight thought necessary for replenishment of liver

and skeletal muscle glycogen stores after an hoursdaily training at 75% VO2max17. In spite of the fact

that the Kalenjin student-athletes ran a daily average Table

1

Nutrientintakesandmajorfoodsource

sofnutrientsofKalenjinrunners(n

12)

asapercentageofdailyenergyintake.Dataareexpressedasmeanvaluesandrangeswiththeir

standarderrors(SE)a

Nutrient

Foodsources(%)

Animal

sources

Vegetable

sources

b

Amount

SE

Range

Maize

Beans

Meat

Milk

Coffee

Kale

Cabbage

Wheat

Energy

(kJ)

13211

283

1186014648

64

17

4

6

0

1

1

4

10

90

Protein

(g)

88

1.8

8096

61

13

11

4

1

2

1

5

15

85

Carboh

ydrate(g)

476

11.7

405538

74

19

0

3

0

0

0

5

3

97

Fat(g)

45.2

1.0

39.950.6

52

8

22

13

0

0

0

3

35

65

a

TablemodifiedfromstudypublishedbyChristensenet

al.5.

b

Includingfoodsourceswhicheachcontributelessthan

1%.

DL Christensen250


3/5

of only 10 km at the time of our study, the intensity oftheir training was probably higher than 75% VO2max.This is indicated by an earlier study on Kenyan run-ners, also including student-athletes based at MarakwetHigh School, who trained at intensities between 72%and 98% in nine out of ten training sessions18. It isreasonable to assume that the very high training inten-sity elicits glycogen depletion to the same extent asexercise of longer duration and lower intensity.

The most optimal glycogen replenishment after train-ing is obtained within the first 3060 min after exer-cise19, due to initial post-exercise synthesis of skeletalmuscle glycogen that does not require the presenceof insulin20. Interestingly, we found that the Kalenjinrunners were fed breakfast and dinner immediatelyafter their early morning run and late afternoon training

session, respectively5

, indicating optimal conditions forskeletal muscle glycogen replenishment. Furthermore,maize has a high glycaemic index21, and as this foodsource was consumed at almost all main meals andalone made up 64% of total energy intake, the glycogenresynthesis conditions may be close to perfect for theadolescent runners while based at the boarding school.

Intakes of protein and essential amino acids

There is disagreement in the research literature con-cerning the protein intake necessary for an enduranceathlete. Using amino acid oxidation, nitrogen balanceor metabolic tracer methodology, several studies2224

but not all25,26 indicate an enhanced proteinrequirement of greater than the 0.8 g kg21 body

weight per day recommended by the Food and Agricul-ture Organization/World Health Organization/UnitedNations University (FAO/WHO/UNU)27. In a studyusing strict energy balance control, Forslund et al.28

showed that an increased energy turnover after aerobicexercise was not due to increased rates of ureaproduction and/or protein synthesis. In our study onadolescent Kalenjin runners, the total daily proteinintake was 1.6 g kg21 body weight, or twice the

amount recommended by FAO/WHO/UNU27. Thiswas higher than the amount suggested by studies thatinvestigated the effect of aerobic training on proteinoxidation and protein requirements23,24,29,30, indicat-ing that the total protein intake of the Kalenjin runners

was more than sufficient to cover their needs. Highintakes of total protein were also found in the studiesof elite Kenyan runners1 as well as ultra-distanceMexican runners13. Thus, for runners based indeveloping countries, including Kenyan athletes,there was no malnutrition at the total protein level.

While the total protein intake was adequate, the

intake of essential amino acids, especially isoleucineand histidine, was low to borderline among the adoles-cent Kalenjin runners5. This is based on the fact that

adolescents are growing and therefore have higherneeds than adults. However, currently there are no rec-ommendations on essential amino acid requirementsfor the adolescent age group above 12 years of ageand younger than 1827. The deficit of some essentialamino acids could be a limiting factor in performance,but it is also possible that a physiological adaptation tolow essential amino acid intakes has taken place, in

which a high protein turnover has resulted in anenhanced re-utilization of essential amino acids5.Such a physiological compensation might have beennecessary only for limited periods throughout the

year, since the runners were supplied with extramilk prior to important competitions, thereby addingextra isoleucine and histidine as well as other essentialamino acids to their diet.

Physiological adaptation to low energyintake?

The first diet study including Kenyan elite male run-ners reported a very low energy intake (9790 kJ)1.Unfortunately the authors did not report data onenergy output during the study period, which coveredsix days over a three-month period. This makes itimpossible to verify energy balance. But even at anestimated low body weight of 5560 kg, there is notmuch energy left for training at the elite level assumingthe runners are in energy balance. It is thereforetempting to theorize that these runners had adaptedphysiologically to low energy intakes in order tocarry out their high-quality and -quantity training asreported by Saltin et al.18. However, one has toapproach such a theory carefully, especially if chronicundernutrition is assumed to take place. Only duringthe first 23 weeks of energy restriction does amarked decrease in basal metabolic rate (BMR) occurthat can be attributed to an increase in metabolic effi-ciency of the active tissue mass (for a recent review,see Shetty31), and hence an indication of metabolicadaptation. With continued energy restriction, how-

ever, any further decrease in BMR is accounted forby the loss of active tissue (i.e. protein)31. The latterseems very unlikely considering the quality and quan-tity of training required at the elite athlete level.This is supported by several studies showing that

VO2max and maximal aerobic power were reduced inundernourished compared with well-nourished youngadults3234. Marginally undernourished adolescentsin Brazil working on a cycle-ergometer showeduncompromised gross mechanical efficiency35. How-ever, this was achieved at the expense of a higherpercentage of their maximum work capacity,

i.e. higher heart rates for the same level of oxygenconsumption. The blood lactate levels were alsohigher during exercise35. The same compromising

Nutrition of Kenyan runners 251


4/5

physiological response could not be seen when adoles-cent and adult elite male Kenyan runners were com-pared with Scandinavian elite male runners in Kenya(altitude) and Denmark (sea level) during treadmilltests in the laboratory18. Furthermore, the study onKalenjin runners dietary intake carried out by ourgroup showed that the runners were in energy balancebased on measurement of energy intake and an esti-mate on energy output over a two-week period5.Based on the above, this author therefore suggeststhat Kenyan elite runners are in energy balance atleast during times of heavy training and competition,and at worst temporarily undernourished.

Conclusions

Distance runners from Kenya consume a diet based ona small range of food items primarily of vegetableorigin that has been shown to provide sufficient carbo-hydrate and total protein intake for endurance ath-letes. Only essential amino acid intake may be in thelow to borderline range, at least for limited periodsof time. Based on the two studies published so faron the dietary intake of Kenyan runners there is con-troversy concerning their energy balance. However,this author suggests that the diet provides for energybalance, and at worst temporary undernourishment,otherwise training and competing at the elite level

would not be possible. It is important to keep inmind that sophisticated dietary studies (for example,using tracer methodology) carried out in the labora-tory have not been done so far for Kenyan runners.The discussions in this paper concerning the physicalperformance of Kenyan runners have therefore beenbased on extrapolations of results from other studiesdone in laboratory environments. It is hoped that, inthe near future, Kenyan runners as well as athletesfrom other developing countries will be participatingin well-controlled laboratory-based studies on dietaryintake and performance. This way we will acquire abetter understanding of the quality of local diets in

the developing world, and add to our knowledge ofpotential physiological adaptation mechanisms ingeneral among athletes with a high habitual dailyenergy turnover.

Acknowledgements

The author is grateful to the runners, athletics coachSamson Kimobwa, the cooking staff and schooladministration at Marakwet High School in Kenya forparticipating in and supporting the dietary studycited in the present paper (reference 5). Furthermore,

this paper and the fieldwork behind it would not havebeen possible without the collaboration and advice ofthe following colleagues (in alphabetical order): Gerrit

van Hall, Leif Hambraeus, Henrik B Larsen and BengtSaltin. This work was supported, in part, by grantsfrom the Team Denmark Research Foundation.

References

1 Mukeshi M and Thairu K (1993). Nutrition and body build:a Kenyan review.World Review of Nutrition and Dietetics72: 218226.

2 Jansen AAJ, Horelli HT and Quinn VJ (1987). Food andNutrition in Kenya: A Historical Review. Kenya: Universityof Nairobi. pp. 1577.

3 Ngare DK and Muttunga JN (1999). Prevalence of malnu-trition in Kenya. East African Medical Journal 76:376380.

4 Leenstra T, Kariuki SK, Kurtis JD, Aloo AJ, Kager PA and terKuile FO (2004). Prevalence and severity of anemia andiron deficiency: cross-sectional studies in adolescent school-girls in western Kenya.European Journal of Clinical Nutri-tion 58: 681691.

5 Christensen DL, van Hall G and Hambraeus L (2002). Foodand macronutrient intake of male adolescent Kalenjin run-ners in Kenya. British Journal of Nutrition 88: 711717.

6 Sutton JEG (1974). The settlement of East Africa. In: BA Ogot(ed.), Zamani: A Survey of East African History, Nairobi:East African Publishing House/Longman. pp. 7097.

7 Nestel PS (1989). Food intake and growth in the Maasai.Ecology of Food and Nutrition 23: 1730.

8 Kipkorir B (1985).Kenyas People: People of the Rift Valley Kalenjin. Nairobi: Evans Brothers (Kenya) Limited.

9 Burke LM, Cox GR, Cummings NK and Desbrow B (2001).Guidelines for daily carbohydrate intake do athletesachieve them? Sports Medicine 31: 267299.

10 Burke LM, Kiens B and Ivy JL (2004). Carbohydrates and fat

for training and recovery. Journal of Sports Sciences 22

:1530.11 Devlin JT and Williams C (1991). Final consensus statement:

foods, nutrition and sports performance. Journal of SportsSciences9(Suppl.): iii.

12 Noakes TD (1997). Challenging beliefs: ex Africa semperaliquid novi. Medicine and Science in Sports and Exercise29: 571590.

13 Cerqueira MT, Fry MM and Connor WE (1979). The foodand nutrient intakes of the Tarahumara Indians in Mexico.

American Journal of Clinical Nutrition 32: 905915.14 Burke LM (1995). Nutrition for the female athlete. In: Krum-

mel D and Kris-Etherton P (eds) Nutrition in WomensHealth. Gaithersburg, MD: Aspen Publishers, pp. 263298.

15 Costill DL, Sherman WM, Fink WJ, Maresh C, Witten M andMiller JM (1981). The role of dietary carbohydrates in

muscle glycogen resynthesis after strenuous running.Amer-ican Journal of Clinical Nutrition 34: 18311836.

16 Burke LM, Collier GR, Beasley SK, Davis PG, Fricker PA,Heeley Pet al. (1995). Effect of coingestion of fat and pro-tein with carbohydrate feedings on muscle glycogen sto-rage. Journal of Applied Physiology 78: 21872192.

17 Pascoe D, Costill DL, Robergs R, Davis JA, Fink WJ and Pear-son D (1990). Effects of exercise mode on muscle glycogenrestorage during repeated days of exercise. Medicine andScience in Sports and Exercise 22: 593598.

18 Saltin B, Larsen H, Terrados N, Bangsbo J, Bak T, Kim CKet al. (1995). Aerobic exercise capacity at sea level and ataltitude in Kenyan boys, junior and senior runners com-pared with Scandinavian runners. Scandinavian Journalof Medicine and Science in Sports 5: 209221.

19 Ivy JL, Katz AL, Cutler CL, Sherman WM and Coyle EF

(1988). Muscle glycogen synthesis after exercise: effect oftime of carbohydrate ingestion. Journal of Applied Physi-ology 64: 14801485.

DL Christensen252


5/5

20 Price TB, Rothman DL, Taylor R, Avison MJ, Shulman GI andShulman RG (1994). Human muscle glycogen resynthesisafter exercise: insulin-dependent and -independent phases.

Journal of Applied Physiology76: 104111.21 Ayuo PO and Ettyang GA (1996). Glycaemic responses after

ingestion of some local foods by non-insulin dependent dia-betic subjects. East African Medical Journal73: 782785.

22 Henderson SA, Black AL and Brooks GA (1985). Leucineturnover and oxidation in trained rats during exercise.

American Journal of Physiology249: E137E144.23 Friedman JE and Lemon PWR (1989). Effect of chronic

endurance exercise on retention of dietary protein. Inter-national Journal of Sports Medicine 10: 118123.

24 Meridith CN, Zackin MJ, Frontera WR and Evans WJ (1989).Dietary protein requirements and body protein metabolismin endurance-trained men. Journal of Applied Physiology66: 28502856.

25 Wolfe RR, Wolfe MH and Shaw JHF (1984). Isotopic deter-mination of amino acid/urea interactions in exercise inhumans. Journal of Applied Physiology 56: 221229.

26 Hood DA and Terjung RL (1987). Effect of endurance train-ing on leucine oxidation in perfused rat skeletal muscle.

American Journal of Physiology253: E648E656.27 Food and Agriculture Organization/World Health Organiz-

ation (WHO)/United Nations University (1985). Energyand Protein Requirements. Report of a Joint ExpertConsultation. Technical Report Series, No. 724. Geneva:WHO.

28 Forslund AH, El-Khoury AE, Olsson RM, Sjodin AM, Ham-braeus L and Young VR (1999). Effect of protein intake

and physical activity on 24-h pattern and rate of macronutri-ent utilization. American Journal of Physiology 276:E964E976.

29 Gontzea I, Sutzescu P and Dumitrace S (1974). The influ-ence of muscular activity on the nitrogen balance and onthe need of man for proteins. Nutrition Reports Inter-national10: 3543.

30 Tarnopolsky MA, Macdougall JD and Atkinson SA (1988).Influence of protein intake and training status on nitrogenbalance and lean body mass. Journal of Applied Physiology64: 187193.

31 Shetty PS (1999). Adaptation to low energy intakes: theresponses and limits to low intakes in infants, childrenand adults. European Journal of Clinical Nutrition 53:S14S33.

32 Viteri FE (1971). Considerations on the effect of nutritionon the body composition and physical working capacityof young Guatemalan adults. In: Schrimshaw NS & AltschulAM (eds) Amino Acid Fortification of Protein Foods. Cam-bridge, MA: MIT Press, pp. 350375.

33 Viteri FE and Torun B (1975). Energy intake and physicalwork in Guatemalan farmers. Bolitin de la Oficina Sam-taria Panamericana 78: 5874.

34 Spurr GB (1983). Nutritional status and physical workcapacity. Yearbook of Physical Anthropology 26: 135.

35 Desai ID (1989). Nutritional status and physical workperformance of agricultural migrants in Southern Brazil.

Proceedings of XIVth International Congress of Nutrition.Seoul: Korean Nutrition Society, pp. 297301.

Nutrition of Kenyan runners 253

diet intake and endurance performance in kenyan runners

Documents