SAMT DEEL 69 12 APRIL 1986 477

Part I. Effect of 1 year's military training on endurance fitness

P. E. KRUGER,

N.

F. GORDON, J. P. VAN RENSBURG, J. MOOLMAN,H. M. S. RUSSELL, H. C. GROBLER, J. F. CILLIERS

Historically, the assumption that military tasks involve a sub-stantial degree of strenuous physical effort has provided therationale for ensuring fitness among military personnel. Despiteconsiderable recent technological advancement and increasingmechanization a high level of physical fitness has remained anessential requisite of the modern-day South African soldier.Irrespective of the energy demands on their daily duties, allSouth Mrican Defence Force (SAD F) personnel require asignificant reserve of physical work capacity in order to copesuccessfully with the emergency situations that have becomean expected feature of today's military life. Furthermore, it

has been suggested that physical conditioning or enhancedfitness also improves morale, sense of well-being, health andsedentary job performance -benefits desirable for all soldiers.!

For these reasons, new SADF recruits participate in arigorous exercise training programme during their initialmonths of military conscription (basic training). It is, however,at present not known whether the current conditioningprogramme, essentially unaltered during the past decade, doesin fact induce the desired enhancement of functional capacity.This is particularly important in view of recent allegations2that the effectiveness of the SADF basic training centres maybe limited by the injurious nature of the physical trainingused.

In contrast with basic training, the emphasis on physicalconditioning is often markedly reduced during the subsequentphases of military service, presumably because of the extensivetime required for specialized task training. It is thereforepossible that the recruit's capacity for physical work mightprogressively deteriorate after basic training, eventually revert-ing to levels similar to those existing before military conscrip-tion. This would obviously negate physical conditioning benefitsderived during basic training. Moreover, the soldier's fitnessmight be inadequate to deal with a fighting situation.

Because of the absence of accurate scientific data relating tothese hypotheses, this prospective longitudinal study wasdesigned as an initial evaluation of the SADF basic trainingprogramme in terms of both physical fitness attained andexertion-related injuries sustained, and to document fitnesslevels on completion of 1 year's military service. Without suchinformation, future planning for improved SADF physicalconditioning programmes will remain speculative.

The effect of military training on endurance fitness levels isdescribed here. In Part II the influence of military service onmuscular strength, power, power-endurance, speed and flexi-bility will be examined. The incidence and nature of exertion-related injuries sustained at an SAD F basic training centrewill be documented in Part III.

Subjects and methods

Because of the short time interval between the arrival of recruitsand the start of basic training, as well as the need to completebaseline evaluations before initiation of the physical conditioningprogramme, the £rst group of recruits reporting in July 1982 formilitary conscription at the large SADF basic training centreunder investigation was briefed on the proposed project. Of theserecruits, 100 presumably healthy randomly nominated subjectswere asked to volunteer for the study and informed consent wasobtained.

I Military Hospital Biokinetic Centre, Voortrekkerhoogte,Pretoria, and MRC Circulation Research Unit, Departmentof Physiology, University of the Witwatersrand, Johannes-burgN. F. GORDON, M.B. B.CH.J. MOOLMAN, M.A.P. E. KRUGER, M.A.H. M. S. RUSSELL, B.A. HONSH. C. GROBLER, B.A. HONSJ. F. CILLIERS, PH.D.Industrial Hygiene Branch, Chamber of Mines of SouthAfrica, JohannesburgJ. P. VAN RENSBURG, M.SC.

The views and opinions expressed and the findings contained in this report are those of theauthors and should not be construed as an official South African Defence Force position,policy or decision, unless so designated by other official documentation.

Experimental proceduresSubjects were initially evaluated during the 10 days before basic

training and then subsequently, using identical experimental

Summary

The effect of the South African Defence Force's(SAD F) military training on the endurance fitness ofrecruits was investigated. Pre-military training maximalO2 consumption (53,14 ml/kg/min) did not changesignificantly during the study. In contrast, lactateturn point (ml 02/kg/min) and treadmill performancetime were moderately enhanced (7,5% and 8%respectively; P < 0,05) by the initial 1O-week basictraining programme. Further analysis of the resultsshowed this endurance-training effect to be limitedto recruits of average and, in particular, below-average fitness. The salutary effect of basic trainingon fitness levels was, however, transient, the valueson completion of 1 year's military training beingunaltered from those before conscription. This pre-liminary assessment of the SADF physical trainingprogramme suggests a need for the introduction ofchanges during and, in particular, after basic training.

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478 SAMJ VOLUME 69 12 APRIL 1986

the recruit wearing field uniform (i.e. long trousers, long sleeveshirt, metal-helmet, web-belt and combat boots); 'battle physicaltraining' 10 for 40 minutes on 4 afternoons each week.

Phase 3 (weeks 6 -8). A 3,2 km run 5 mornings each week withthe recruit wearing field uniform and carrying his rifle; 'riflephysical training'IO for 40 minutes on 4 afternoons each week.

Phase 4 (weeks 9 and 10). A 3,2 km run 5 mornings each weekwith the recruit wearing field uniform and webbing and carryinghis rifle; 'buddy physical training'IO for 40 minutes on 4 afternoonseach week.

Statistical methodsSignificance of differences between experimental variables was

analysed using one-way analysis of variance (ANOV A), followedby the Scheffe procedure when a significant F ratio was obtained.Statistical significance was established at the 0,05 confidence level.

Results

Pre-basic training medical evaluationOf the 100 recruits selected for this study 7 were not issued

with full medical clearance for participation in all aspects ofmilitary training. Their results were therefore excluded from thestudy. Thus, the subjects initially comprised 93 medically-fityoung adult South African national servicemen. The pre-basictraining physical characteristics of these recruits are listed inTable I. Before starting national service the recruits smoked 4 :t: 7(mean :t: SD) cigarettes/day, and their smoking habits did notchange significantly during the study. Because of injury, illness,death (2 recruits in motor vehicle accidents while on leave frommilitary training), scheduling conflicts, equipment malfunction,and voluntarily declining participation in certain evaluation pro-cedures, the samples of recruits performing the different experi-mental procedures and test sessions varied in numbers.

procedures, during the final 10 days of basic training and oncompletion of 1 year's military service. During the final testperiod only those subjects who had completed the previous twoevaluations were investigated.

Recruits were required to complete an activity history question-naire before testing. Because cigarette smoking may influencemaximal aerobic capacity,3 the number of cigarettes smoked perday was also recorded. Nude body weight and height weremeasured using a calibrated Detecto medical scale. To estimatepercentage body fat (%BF) the sum of four skinfolds (biceps,triceps, subscapular and suprailiac), measured by Harpenden skin-fold calipers, was used together with the formulae of Durnin andRahaman4 and Siri.5 Anthropometric characteristics determinedwith a standard Martin-type anthropometer, sliding caliper, andsteel tape, were employed together with skinfolds to calculatesomatotypes according to the Heath-Carter method.6

Subjects avoided strenuous physical activity for 24 hours beforeexercise testing and abstained from meals, tea, coffee, cola bever-ages and cigarettes for at least 3 hours before exercise. All subjectswere given an initial familiarization trial. For each subject, maximalO2 consumption (V 02 moo), maximal heart rate (HRmaJ, lactateturnpoint (LAtp), and other relevant cardiorespiratory variableswere measured using a discontinuous graded treadmill exercisetest. Subjects commenced walking,on a Quinton (model 18 -60)motor driven treadmill at a speed of 5 kmlh and a gradient of 5%.The gradient remained constant and the speed was increased by1,5 kmih with each successive 3-minute workload until volitionalexhaustion. Subjects rested in the standing position for 1 minutebetween exercise bouts. Respiratory gas exchange was measuredwith a Cardio-Pulmonary Instruments Model 7000 AerobicMeasurement System.7 Subjects breathed through a low resistanceHans Rudolph valve, the expired air being routed via a condenserunit into the input port of a dry rolling seal spirometer with amaximum capacity of 7,51. Volumetric displacement was convertedinto electrical impulses, which were counted over each 60 secondperiod and subsequently further converted into volumetric unitsfor processing and display by the data reduction package.Temperature was monitored by a thermal sensor located inside thespirometer chamber and employed for gas volume corrections.Expired air was sampled continuously from the exit port of thespirometer at a rate of 0,5 Vmin for determination of mixedexpired CO2 and O2 concentrations with an infrared absorptionCO2 analyser and a polarographic O2 analyser respectively, at theend of each 60 second test interval. The gas analysers werecalibrated by room air and standard concentrations of tank gasbefore and after each exercise test. The heart rate was read fromthe electrocardiogram (CM5 placement), which was co~tinuouslydisplayed on a Mennen oscilloscope, during .the final 10 seconds ofeach 60 seconds of exercise. Peak heart rate and O2 consumptionattained during exercise were taken as V02 max and HRmax,respectively.

Venous blood samples (approximately 2 ml) were obtainedimmediately on completion of each 3-minute work load from anantecubital vein through an indwelling vein infusion set(Venisystems, Butterfly-19, Cat. No. 4590) kept patent with sterileheparinized saline (5 lUll). Before sampling, approximately 1,5ml of fluid was withdrawn and discarded. Blood samples wereimmediately placed in ice-cold 0,6N perchloric acid, the pre-cipitated protein being removed by centrifugation, and bloodlactate concentrations determined enzymatically.8 For each subjectthe relationship between blood lactate and submaximal O2 con-sumption was approximated by means of a biphasallinear regres-sion model as described by Van Rensburg el al.9 LAtp was definedas the O2 consumption at which blood lactate levels commenced torise exponentially, and expressed as % VOz max and ml Oz/kg/min.Treadmill exercise performance time was calculated by subtractingthe rest intervals from the total exercise test duration.

Effect of SADF basic training and subsequentmilitary training on endurance fitness

The effect of SADF military training on cardiorespiratoryvariables at maximal effort, LAtp, and endurance performance isdocumented in Table II. The pre-basic training VO2 max of 53,14 :t4,69 ml/kg/min did not change significantly during the testperiod. In contrast, LAtp (ml 02/kg/min) and maximal treadmillexercise performance time were moderately (7,5% and 8% increaserespectively) and statistically significantly enhanced by basic train-ing. The observed endurance training effect was, however, transientand fitness levels were unaltered from those documented beforemilitary conscription on completion of 1 year's SADF militaryservice.

Physical conditioning during basi~ trainingThe 10-week basic training programme consists of 4 phases of

conditioning:Phase 1 (weeks I and 2). A 3,2 km run 5 mornings each week

with the recruit wearing shorts, vest and 'takkies' (plimsolls); lightcalisthenics for 40 minutes on 4 afternoons each week.

Phase 2 (weeks 3 -5). A 3,2 km run 5 mornings each week with

Stratification of training effect on basis ofinitial fitness level

In an attempt to determine why the recruits showed no averageimprovement in VO2 ma. with basic training in the present study,

479SAMT DEEL 69 12 APRIL 1986

below-average fitness category responded to basic training withmarked, statistically significant improvements in V02 max(ml/kg/min, 8% increase), LAtp (ml 02/kg/min, 20% increase;%V02max, 11% increase), and treadmill performance time (22%increase) (Fig. 1). Furthermore, while the %BF of the entire studygroup remained unaltered during military training (Table III),basic training significantly reduced %BF of those of below-averagefitness. The salutary effect of basic training on V02 max, LAtp,exercise performance and %BF could, however, not be observedon completion of 1 year's military service in these recruits. Incontrast with the below-average fitness recruits the average recruitsfailed to enhance their V 02 max significantly during basic training(Fig. 2). Moreover, the V02max of the above-average fitness recruitstended to decrease together with LAtp and exercise performanceduring military training (Fig. 3).

TABLE II. EFFECT OF SADF MILITARY TRAINING ON LA,p

AND SELECTED MAXIMAL CARDIORESPIRATORY

VARIABLES (MEAN:\: SD)

Pre-BT Post-BT Post 1 yr

V02max (l/min) 3,62:\:0,58 3,72:\:0,54 3,69:\:0,51

V02max (ml/kg/min) 53,14:\:4,6955,04:\:4,41 52,98:\:3,99

LA,p (% V02max) 71,7:\:10,8 74,6:\:8,7 70,2:\:8,5

LA,p(ml/kg/min) 38,39:\:6,6741,26:\:5,17* 37,17:\:4,57

R 1,09:\:0,04 1,08:\:0,03 1,09:\:0,03

VE(l/min) 128,6:\:13,5131,5:\:14,1 129,4:\:12,8

VC02 (l/min) 3,95:\:0,65 4,02:\:0,60 4,03:\:0,59

HRmax (beats/min) 196:\:7 194:\:7 195:\:6

T(min) 20,8:\:2,8 22,5:\:2,7* 20,6:\:1,6

ForVo,... (1/min). Vo,~. (ml/kg/min). R, VE...vco,. HR.u. and T -N= 85 pre-Bt; N= 65 post-BT; and N= 53 post 1 yr.For LAo, (% Yo, ~.) and LA" (ml/kg/min) -N= 83 pre-BT; N = 64 post-BT; and N= 52 post 1 yr.Vo,~. = maximal 0, consumption; LA" = lactate turnpoint; R = respiratoryexchange ratio; VE = pulmonary ventilation; Yco, = CO, output; HR~. = maximalheart rate; T = performance time; pre-BT = pre-basic training; post-BT = post-basic training; and post 1 yr = on completion of 1 year's military training..p < 0,05 versus pre-BT and post 1 yr

they were divided into three groups on the basis of their initialLAtp (ml 02/kg/min). The LAtp expressed as ml 02/kg/min wasselected for this purpose because endurance performance changeshave been shown to be more directly accounted for by thisvariable than other physiological attributes.II-13 Recruits in the

TABLE III. EFFECT OF SADF MILITARY TRAINING ONWEIGHT, % BF AND LBM (MEAN :t SD)

Pre-BT post-aT Post-1 yr

(N= 93) (N= 84) (N= 62)

Weight (kg) 67,8:t9,5 68,3:t8,3 69,4:t10,3Body fat (%) 13,6:t3,2 13,O:t2,4 13,8:t3,5LBM (kg) 58,4:t7,2 59,4:t6,8 59,7:t7,6

% BF = percentage body fat; LBM = lean body mass; pre.BT = pre-basic training;post-BT = post-basic training; post 1 yr = on completion of 1 year's military

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Fig. 2. Effect of SADF military training on endurance fitness levels of 19 average fitness recruits (mean:!: SEM)(Vo, ill" = maximal O2 consumption; LAtp = lactate turnpoint; T = performance time; HRill" = maximal heart rate; B =before basic training; A = after basic training; 1 yr = on completion of 1 year's military training) (*** P < 0,05 v. Band 1 yr).

42,0 mVkg/min, 46,7 ml/kg/min, 50,7 ml/kg/min and 55,1ml/kg/min recently reported for male British,IS Canadian,19US20 and Finnish21 recruits, respectively.

Research has indicated that measures other than V 02 maxalone may be important determinants of endurance fitness.22One such measure, the popularity of which has recentlyincreased dramatically, is the 'anaerobic threshold'. Themeasured 'anaerobic threshold' is, however, affected by a widevariety of experimentaI settings including site of blood sampl-ing, precise definition of the point at which the 'anaerobicthreshold' ensues, use of invasive versus noninvasive pro-cedures, and exercise protocol employed.23-25 The presentLAtp therefore cannot be scientifically equated with the'anaerobic thresholds' of previous studies with different metho-dology (the term 'lactate turnpoint' is used in preference to'anaerobic threshold' when referring to the present O2 con-sumption-blood lactate relationships in order to avoid anyimplication of causality).

Likewise, before interpreting and comparing the %BF valueswe recorded, one must be cognizant of the limitations andadvantages of the methods used in the various studies. Densito-metric underwater weighing techniques are generally consideredthe more accurate methods of determining body composition.26However, estimates of %BF from skinfolds correlate reasonablywell with recordings obtained by densitometry,26.27 and it thusappears feasible to interpret the 13,6 %BF observed in ourstudy as characteristic of an active population. Moreover, the%BF of SADF recruits falls comfortably within the 13,6 -17,1% and 12,5 -17,6% ranges documented for US28-30 andBritish soldiersI8.26.31 respectively.

Discussion

Pre-basic training endurance capacity, fitnessand % BF

The pre-basic training Vol max of 53,14 ml/kg/min isconsiderably higher than the value of 47,7 ml/kg/min docu-mented by Wyndham's groupl4 in 1966 for 80 fit young SouthAfrican white males. Before the findings of the two studies canbe compared, methodology and subject populations must beequated. Although both studies utilized similar exercise testingprocedures, no explicit mention is made of Wyndham et al. 'S14subject sampling methods, or the ages, health status andleisure time physical activity levels of their subjects. This is ofutmost importance since 7 subjects initially presumed fit wereexcluded from our investigation after medical screening, whilea physical activity questionnaire revealed that 3 subjects hadparticipated in endurance sports on a provincial level, 6 on aclub level, and a further 7 had begun an endurance trainingprogramme in preparation for military service. Therefore, it isnot possible to interpret our findings as indicating an improve-ment in maximal aerobic capacity of young South Africanmales during the past 2 decades, although this postulatecannot be ignored.

Additional problems including mode of exercise, extrapola-tion of results of indirect tests, and effects of altitude onVol max are confronted when making comparisons with foreignarmed forces.ls-l? However, although comparisons should beviewed with caution, it is apparent that the Vol max of thepresent SADF recruits compares favourably with the values of

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481SAM" DEEL 69 12 APRIL 1986

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Fig. 3. Effect of SADF military training on endurance fitness levels of 18 above-average fitness recruits (mean :f:SEM) (VO2m" = maximal O2 consumption; LA,p = lactate turnpoint; T = performance time; HRm" = maximal heartrate; B = before basic training; A = alter basic training; 1 yr = on completion of 1 year's military training).

test because of exertion-related injuries incurred during basictraining. This fact considerably alters the interpretation of thepresent results of the actual efficacy of the SADF basictraining programme.

While the programme could be considered effective inenhancing or maintaining endurance fitness levels in themajority of uninjured recruits, its feasibility is severely limitedby the injurious nature of the conditioning modes used. Thisis seemingly applicable to recruits with low initial fitness levelswho comprised more than 50% (8) of those injured. Althoughthe incidence and nature of exertion-related injuries will bediscussed in detail in Part III of this study and are consideredto be multifactorial in origin, the present findings suggest thatif all recruits are to derive significant improvements inendurance fitness and if the risk of injury induced by trainingis to be minimized, then it would appear to be prudent tostratify and train recruits in accordance with their pre-basictraining fitness levels as is currently the situation in the USArmy.

Effect of SADF basic training on endurancecapacity and fitness

A review of endurance training studies performed on youngadult males indicates that moderate intensity programmes ofrelatively short duration can be expected to induce a change inVo2 max of approximately 10%.32 Similar data on alterations in'anaerobic threshold' are scarce but suggest that this para-meter max be more responsive to endurance conditioning thanV02 max~3- 5 As a group, the SADF recruits displayed an insig-

nificant increase in V 02 max accompanied by only moderateimprovements in LA,p after basic training.

The reasons why a conditioning programme of the presentduration, frequency and intensity did not enhance these para-meters more were unclear until the recruits were subdividedon the basis of their initial endurance fitness levels as assessedby their LA,p expressed in ml 02/kg/min. This procedurerevealed that the basic training programme provided the below-average and possibly the average, but not the above-averagefitness recruits with an adequate training stimulus. Whether ornot this is adequate will depend largely on the fitness require-ment for subsequent job assignments and emergency situations,a factor currently undergoing investigation in the SADF.

However, in the assessment of a physical training regimendata pertaining to injuries sustained should be included inorder to incorporate the element of feasibility of the particularapproach. It is therefore noteworthy that 17% (14) of therecruits reporting for the post-basic training test session wereunable to perform or complete the graded treadmill exercise

Endurance fitness levels on completion of 1year's SADF military service

On completion of I year's SADF military service recruitfitness levels were insignificantly altered from those beforemilitary conscription but were less than those attained duringbasic training. The deterioration in endurance fitness afterbasic training is most evident when analysing the results of the

482 SAMJ VOLUME 69 12 APRIL 1986

recruits who improved most significantly during basic training,i.e. the below-average fitness recruits. The major limitation ofthese findings is the likelihood that although physical trainingis to a large degree standardized at all SADF basic trainingcentres, this is not true of the remainder of military service.Thus, while the need to increase the emphasis on physicaltraining in certain SADF units after basic training has beenestablished

beyond doubt by the present results, furtherresearch will be needed before extrapolating this conclusion tothe

entire SADF.

Conclusions

This initial assessment of the efficacy of the SADF physicaltraining programme has demonstrated the need for the intro-duction of changes during and, in particular, after basic train-ing. Recruits should probably be categorized and receive basictraining on the foundation of their pre-entry endurance fitnesslevels, and the emphasis on physical fitness should be increasedthereafter. Such an approach, when coupled with adherence toscientifically validated physical training principles, is likely toensure optimum development and maintenance of endurancefitness, thereby enhancing the effectiveness of the SADF.

We thank Colonel D. P. Myburgh and Professor C. Rosendorfffor reviewing this manuscript, Captain M. E. F. Visser and therest of the I Military Hospital laboratory staff for performing theblood analyses, and Captain R. Barnes for performing the statisticalanalyses.

10. Cilliers JF. Die fisieke werkvermoe van liggaamlike opleidingsinstrukteurs indie Suid-Afrikaanse Leer na II weke opleidingsprogram. M.A. (Phys. Ed.)thesis, University of Pretoria, 1979.

II. Kumagai S, Tanaka K, Matsuura Y, Matsuzaka A, Hirakoba K, Asano K.Relationships of the anaerobic threshold with the 5 km, 10 km, and 10 mileraces. Eur J Appl Physiol1982; 49: 13-23.

12. Tanaka K, MatsuuraY, Kumagai S, Matsuzaka A, Hirakoba K, Asano K.Relationships of anaerobic threshold and onset of blood lactate accumulationwith endurance performance. Eur J Appl Physiol1983; 52: 51-56.

13. Tanaka K, Matsuura Y, Matsuzaka A et al. A longitudinal assessment ofanaerobic threshold and distance-running performance. Med Sci SportsExerc 1984; 16: 278-282.

14. Wyndham CH, Strydom NB, Leary WP. Studies of the maximum capacityof men for physical effort, Part II. Int Z Angew Physiol Einsch/ Arbeitsphysiol1966; 22: 296-303.

15. Davies CTM. Limitations to the prediction of maximum oxygen intake fromcardiac frequency measurement. J Appl Physiol1968; 24: 700-706.

16. Wyndham CH, Strydom NB,Leary WP, Williams CG. Studies of themaximum capacity of men for physical effort, Part 1. Int Z Angew PhysiolEinschl Arbeitsphysioll966; 22: 285-295.

17. Buskirk ER, Kollias J, Piconreatique E, Akers R, Prokop E, Baker P.Athletes at various altitudes in United States and Peru. In: Goddard RF, ed.International Symposium of the Effect of Altitude on Physical Performance.Chicago, Ill.: Athletic Institute, 1960.

18. Vogel JA, Crowdy JP, Amor AF, Worsley DE. Changes in aerobic fitnessand body fat during army recruit training.' Eur J Appl Physiol 1978; 40:37-43.

19. My\~s WS, Allen CL. A survey of aerobic fitness levels in a Canadianmilitary population. Aviat Space Environ Med 1979; 50: 813-815.

20. Vogel JA,. Ramos MU, Patton JF. Comparisons of aerobic power andmuscle strength between men and women entering the US Army. Med SciSports 1977; 9: 58.

21. Vainikka M. The physical fitness of conscripts at the beginning and at theend of the military basic training period. Ann Med Milit Fenn 1978; 53:19-28.

22. Astrand P-O, Rodahl K. Textbook of Work Physiology. New York: McGraw-Hill, 1977.

23. Withers RT, Sherman WM, Miller JM, Costi.11 DL. Specificity of theanaerobic threshold in endurance trained cyclists and runners. Eur J ApplPhysio11981; 47: 93-104.

24. Yoshida T, Takeuchi N, Suda Y. Arterial versus venous blood lactateincrease in the forearm during incremental bicycle exercise. Eur J ApplPhysiol1982; 50: 87-93.

25. Powers SK, Dodd S, Garner R. Precision of ventilatory and gas exchangealterations as a predictor of the anaerobic threshold. Eur J Appl Physiol1984; 52: 173-177.

26. Behnke AR, Wilmore JH. Evaluation and Regulation of Body Build andComposition. Englewood Cliffs, NJ.: Prentice-Hall, 1974.

27. Haisman MF. The assessment of body fat content in young men frommeasurement of body density arid skinfold thickness. Hum Bioi 1970; 42:679-688.

28. Pascale LR, Grossman MI, Sloane HS, Frankel T. Correlation betweenthickness of skinfolds and body density in 88 soldiers. Hum Bioi 1956; 28:165-176.

29. Krzywicki JJ, Chinn KSK. Body composition of a military population, FortCarson, 1963. AmJ Clin Nutr 1967; 20: 708-715.

30. Knapic JJ, Burse RL, Vogel JA. Height, weight, percent body fat, andindices of adiposity for young men and women entering the US Army. AviatSpace EnvironMed 1983; 54: 223-231.

31. Amor RF. A survey of physical fitness in the British Army. In: Proceedingsof the First Physical Fitness Symposium with Special Reference to MilitaryForces. Toronto: NATO, 1978.

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35. Denis C, Fouquet R, Poty P, Geyssant A, Lacour JR. Effect of 40 weeks ofendurance training on the anaerobic threshold. Int J Sports Med 1982; 3:208-214.

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