Eur J Appl Physiol (1993) 67:150-158 European Jouma, of Applied Physiology and OccupationalPhysiolegy © Springer-Verlag 1993 Aerobic and anaerobic indices contributing to track endurance cycling performance N. P. Craig 1, K. I. Norton 2, P. C. Bourdon 1, S. M. Woolford 1, T. Stanef 1, B. Squires 2, T. S. Olds z, R. A. J. Conyers 3, and C. B. V. Walsh 4 1 South Australian Sports Institute, PO Box 219, Brooklyn Park SA 5032, Adelaide, South Australia, Australia 2 School of Sport and Leisure Studies, University of New South Wales, Oatley, Australia 3 Department of Biochemistry, Alfred Hospital, Melbourne, Victoria, Australia 4 Australian Institute of Sport, Kidman Park, Adelaide, South Australia, Australia Accepted February 24, 1993 Summary. A group of 18 male high performance track endurance and sprint cyclists were assessed to provide a descriptive training season specific physiological profile, to examine the relationship between selected physiological and anthropometric variables and cycling performance in a 4000-m individual pursuit (IP4ooo) and to propose a functional model for predicting success in the IP4ooo. Anthropometric characteristics, absolute and relative measurements of maximal oxygen uptake (1202max), blood lactate transition thresholds (Thla- and Than,i), 1202 kinetics, cycling economy and maximal accumulated oxygen deficit (MAOD) were assessed, with cyclists also performing a IP4ooo under competition conditions. Peak post-competition blood lactate concentrations and acid-base values were measured. Although all corresponding indices of Th~a- and Than, i occurred at significantly different intensities there were high intercorrelations between them (0.510.85). There was no significant difference in M A O D when assessed using a 2 or 5 min protocol (61.4 vs 60.2 m l . k g - 1, respectively). The highest significant correlations were found among IP4ooo and the following: VO2max (ml'kg-2/3" min-1; r = - 0.79), power output at lactate threshold (Wth,~) (W; r = -0.86), half time of 1202 response whilst cycling at 115% 1202ma~ (s; r=0.48) and M A O D when assessed using the 5 min protocol (ml.kg -1; r = - 0.50). A stepwise multiple regression yielded the following equation, which had an r of 0.86 and a standard error of estimate of 5.7 s: IP4000 (s) = 462.9 - 0.366 x (Wthla) -- 0.306 x ( M A O D ) 0.438 x (1202max) where Wth, is in W, M A O D is in ml.kg -1 and 12Ozmax is in ml. kga- 1. min - 1. These results established that these male high performance track endurance cyclists had well-developed aerobic and anaerobic energy systems with VO2m~x, Thla and M A O D being primary important factors in a IP4ooo. Therefore, it is suggested that these variables should be optimally trained and routinely monitored Correspondence to" N. Craig when preparing track endurance cyclists for competition. Key words: Individual pursuit - Maximal oxygen uptake - Lactate threshold - Oxygen uptake kinetics Maximal accumulated oxygen deficit Introduction For master coaches to construct and implement specific physical training programmes and/or identify talent, they must first have access to fundamental information concerning the essential qualities for successful sporting performance. This may include the development of a functional model to determine the relative contribution and kinetics of energy metabolism and other physiological factors that contribute to the performance specialty. The knowledge and understanding of energy costs and the involvement of various metabolic components will enable the coach and sports scientist to competently prescribe training programmes, develop specific assessment protocols and maximise training and competition performance. Whilst this modelling concept is not new and has been applied to many sports, in the sport of high performance cycling, most attention has been focused on road cycling (Coyle et al. 1988, 1991; Krebs et al. 1986; Miller and Manfredi 1987). Relatively little research has been conducted on identifying the important physiological characteristics of track cyclists in relation to their specific cycling events. The principal track cycling events range from a 200m flying sprint lasting 10-11 s to the 50-km points score lasting approximately 1 h. Unlike road cycling and the longer track cycling events, where the majority of competition is completed at submaximal levels of metabolism, the shorter track cycling events require the cyclist to tax maximally both the aerobic and anaerobic metabolic pathways (Neumann 1992). Of particular interest to this study was the 4000-m individual pursuit (IP4ooo). 151 This e v e n t r e q u i r e s a n i n d i v i d u a l cyclist, f r o m a stat i o n a r y start, to p r o p e l as fast as p o s s i b l e a s p e c i a l l y designed light-weight bicycle with a fixed gear over a d i s t a n c e o f 4000 m. It is an e v e n t t h a t lasts a p p r o x i m a t e l y 270 s at i n t e r n a t i o n a l l e v e l u n d e r c o m p e t i t i o n c o n d i t i o n s a n d p l a c e s a high d e m a n d o n b o t h t h e a e r o b i c a n d a n a e r o b i c e n e r g y p a t h w a y s ( B u r k e et al. 1981; F a i n a et al. 1989; K e e n et al. 1985; N e u m a n n 1992; P y k e et al. 1988). I t has b e e n s u g g e s t e d t h a t t h e r e l a tive c o n t r i b u t i o n s of a e r o b i c a n d a n a e r o b i c m e t a b o l i s m to this s u p r a m a x i m a l e v e n t a r e a p p r o x i m a t e l y 80% a n d 2 0 % , r e s p e c t i v e l y ( F a i n a et al. 1989; N e u m a n n 1992). W h i l s t s e v e r a l s t u d i e s h a v e r e p o r t e d d a t a o n t h e ene r g e t i c s ( B u r k e 1986; F a i n a et al. 1989; M a r i o n a n d L e g e r 1988; N e u m a n n 1992), p h y s i c a l a n d a n t h r o p o m e t r i c c h a r a c t e r i s t i c s ( M c L e a n a n d P a r k e r 1989; N e u m a n n 1992; P y k e et al. 1988) a n d t e s t p r o t o c o l s ( C r a i g et al. 1989) f o r t r a c k cyclists, n o a t t e m p t h a s b e e n m a d e to i d e n t i f y t h e k e y p h y s i o l o g i c a l v a r i a b l e s assoc i a t e d w i t h high p e r f o r m a n c e t r a c k cycling. H e n c e , t h e p u r p o s e s of this s t u d y w e r e to: 1. E x a m i n e t h e r e l a t i o n s h i p b e t w e e n s e l e c t e d p h y s i o l ogical and anthropometric variables, including oxygen uptake (VO2) kinetics and maximal accumulated oxyg e n d e f i c i t ( M A O D ) , a n d cycling p e r f o r m a n c e in a IP4o00, 2. P r o p o s e a p h y s i o l o g i c a l m o d e l f o r p r e d i c t i n g success in t h e IP40o0, a n d 3. P r o v i d e a t r a i n i n g s e a s o n specific p h y s i o l o g i c a l p r o file o n h i g h p e r f o r m a n c e m a l e t r a c k cyclists. Methods Subjects. A group of 18 male high performance track endurance (n = 12) and sprint cyclists (n =6) participated in the study. All cyclists were scholarship holders at either the Australian or South Australian Institute of Sport. Ability levels ranged from State level competitors to World Champions with 6 of the 18 representing Australia at the 1992 Olympic Games. The cyclists were fully acquainted with the laboratory testing procedures with possible risks being fully explained to the subjects before they gave their written consent. The cyclists were requested to participate in only light-recovery (less than 50 km at less than 75% maximal heart rate) training 24 h before any test. Laboratory testing was performed over a 10-day period while all track testing was performed on 1 day. Testing was conducted at the end of a 4-week transition (recovery) phase of their yearly training programme. Anthropometry. Stretch standing height was measured to the nearest 0.1 cm with a wall stadiometer. Body mass was measured to the nearest 50 g with calibrated Mettler TE electronic platform scales, with the cyclist wearing cycling knicks. Eight skinfold sites were measured (Telford et al. 1988) and subsequently used to estimate relative body fat according to the guidelines outlined by Withers et al. (1987). The body surface area for each subject was computed from the equation of Dubois and Dubois (1916). Measurement of 1202. All 1102 measurements were determined using a breath-by-breath system (Ametek OCM-2, Ametek Pittsburgh, Pa., USA). For further analysis, and to avoid some of the inherent random variations, data were averaged and plotted for 10-s intervals. The metabolic assessment system incorporated a low-resistance valve (Hans Rudolf 2700, Kansas City, Mo., USA) attached to an inertially-compensated unidirectional turbine volume transducer (Ametek). Expired gas samples were continually monitored for 02 and CO2 concentrations by a S3A/I 02 analyser (Ametek) and a CD-3A CO2 analyser (Ametek), respectively. A time delay factor was used to align inspiratory gas volumes with expiratory gas analysis. The gas analysers were calibrated before and after each test using reference gases prepared by measuring the mass of each gas component, while the volume transducer was checked using a 1-1 syringe. Cycle ergometer. All physiological tests were conducted on a sport-specific, geared air-breaked cycle ergometer using a 23 tooth front fly-wheel sprocket. Further details of the ergometer have been published previously (Craig et al. 1989). The ergometer was calibrated dynamically throughout the physiological range of measurement using a torque meter. During each test, the ergometer was linked to a computer which continuously measured and stored total work done and other associated work indices using specifically designed software. These indices were automatically corrected for changes in atmospheric temperature and pressure. Heart rate. A Polar Sport Tester PE-4000 (Polar Electro OY, Hakamaantie, Kempele, Finland) heart rate monitor was used to monitor and store heart rate every 5 s during the laboratory and field tests. At the end of each test, the stored heart rate information was transferred to a computer using the Polar heart rate analysis software for graphing and data analysis. A heart rate calibrator was used to verify the accuracy of the Polar Sport Tester at rates of 50, 100, 150, 200, and 210 beats.min-1. Blood biochem&try. At the completion of the laboratory and field tests, arterialised capillary blood was taken from a hyperaemic fingertip. Hyperaemia was induced by liberally smearing the fingertip with a cutaneous vasodilator (Finalgon: Boehringer Ingelheim) 10-15 min before the capillary sample was required. Arterialised capillary blood has been shown to be an acceptable alternative to arterial blood for measurement of acid-base status (McEvoy and JoneS 1975). The blood sampling method was standardised in the following manner: 1. Prior to puncturing with an autolet, the fingertip was cleaned with an alcohol swab and wiped dry with a tissue; 2. The first drop of blood was discarded and then 25-125 ixl whole blood was collected within 30 s in a heparinised glass capillary tube(s); 3. The blood specimen was immediately analysed for lactate concentration and acid-base status. Blood lactate was analysed using the automatic 1500 Sport LLactate analyser (YSI Incorporated, Yellow Springs, USA) while acid-base status was measured using an ABL30 Acid-Base analyser (Radiometer, Copenhagen, Denmark). Both analysers were calibrated using precision standards, buffers and gases prior to and during test sessions. Maximal oxygen uptake. Maximal oxygen uptake (1202max) was assessed using a continuous incremental cycling test lasting between 8 to 12 rain. Warm-up was not standardised, rather, subjects were instructed to prepare as they would in readiness for competition. After completion of the warm-up, the cyclists were required to pedal at a constant intensity for l-rain, commencing at 200 W and increasing by 25 W each minute. The cyclists pedalled for complete minutes, even though during the last minute they may have been unable to sustain the required intensity. The fixed gear ratio employed enabled the cyclists to complete the test in the cadence range of 120-130 rpm. Metabolic and heart rate data were measured every 10 and 5 s respectively, while total work done was recorded.every 60 s. The attainment of 1202~ax was accepted when the VO2 for successive increments of 25 W differed by less than 0.15 1.min-1 and was expressed in absolute and relative terms according to the procedures of Nevill et al. (1992). 152 Blood lactate transition thresholds. Determinations of lactate threshold (Thl,-) and individual anaerobic threshold (Th,n,i) were made during a 30-40 min continuous incremental cycling test. After a warm-up, each cyclist was required to pedal at a constant power output for 5 min, beginning at 100 W and increasing by 50 W. The test was complete when the cyclists could no longer maintain the required power output. The 1202 was measured during the last 2 min of each 5 min and these steady-state values were used to determine for each subject, the linear relationship between 1202 and power output, thus expressing the oxygen demand for all cycling intensities. Heart rate and work done were measured and stored continuously. Arterialised blood samples were taken at rest, during the last 30 s of each exercise period and at 1, 2, 5, 7 and 10 rain post-test for the determination of lactate concentration and acid-base status. The cyclists remained seated during the post-test recovery period. The Th~- was defined using the method proposed by Beaver et al. (1985) while Th~,,i was determined using a modification of the method described by Stegmann et al. (1981). Individual data points for both the exercise and recovery blood lactate concentrations were plotted as a continuous function against time and were fitted with a third order polynomial. Both blood lactate transition thresholds were expressed in terms of corresponding lactate concentration, power output, 1202, heart rate, and acidbase status. Cycling economy. Two methods were used to quantify cycling economy, both of which used the submaximal steady-state data collected during the blood lactate transition threshold test. The first approach required the calculation of the slope and intercept for the regression line between 1202 (both absolute and relative) and power output for each cyclist. The second method was that proposed by Van Handel et al. (1988), which, after computing the above regression line (relative VO2 vs power output), required the calculation of an economy score for each cyclist. 1202 kinetics. To assess 1202 kinetics cyclists were required 1. To cycle to exhaustion at a constant intensity equivalent to 115% of their 1202max and 2. To cycle at a constant submaximal intensity of 250 W for 3 rain. The 1202 was measured for 2 min prior to exercise and continuously throughout both tests. To characterise the kinetic behaviour of 1202 during each test, the data were fitted to the following equation using iterative procedures of a nonlinear least squares regression: 1202 (t) = 1202int+ (VO2ss -- 1202int)"(1 - e -t"~ where 1202(0. is the 1202 at time (t) rain, 1202int is the initial or pre-exercise VO2, 1202~s is the final (steady-state) 1202 and ris a time constant (Linna.rsson 1974). The time constant describes the rate of increase of VO> Half-times (s) to reach 1202ss were further computed by multiplying r by 41.58 (Hagberg et al. 1978). using their road bikes and wearing racing attire. Environmental conditions were relatively constant during the test period (temperature, 22.4-24.4 ° C; barometric pressure, 769.4-769.8 mmHg; relative humidity, 36.0%-44.0%; wind speed, 0.4-2.43 m - s - l ) . Heart rate was measured and stored continuously during the IP4000 with blood sampling occurring at 1, 2, 5 and 7 rain post IP40o0 for the determination of peak values of blood lactate and acid-base status. Statistical analys&. Descriptive statistics were performed on the group data using standard statistical procedures. Least squares linear regression analysis was used to calculate correlation coefficients among and between independent variables (laboratory measures) and the dependent variable (IP4oo0 time). Stepwise multiple regression analysis was performed to determine the best possible combination of independent variables to predict the dependent variable. Paired Student's t-tests were used to determine differences in anaerobic capacity when assessed with the 2- and 5-rain tests, between indices relating to the two blood lactate transition thresholds and between post-test blood measures of the IP4o0oand 5-rain test. A significance level of P<0.05 was used in all analyses. Results The physical characteristics of the subjects used in this study are presented in Table 1. None of these variables was significantly correlated with IP4ooo. Table 2 summarises the physiological measurements of l?O2max, 1)'O2 kinetics during submaximal and supramaximal cycling, cycling economy and anaerobic capacity determined by both a 2- and 5-min supramaximal protocol. All indices of l)Ozmax were significantly correlated to IP4ooo, with correlation coefficients ranging r = - 0 . 6 1 for VO2m~x (1.rain-*) to r = - 0 . 7 9 for relative l)O2m~x (ml.kg-2/3. min-1). In addition, maximal minute ventilation (body temperature and pressure, saturated with water vapour; l'min-*) and the power output (W) at which VO2m~x was reached were also significant predictors of IP4000 ( r = - 0 . 4 9 and r = - 0 . 7 9 , respectively). Of particular interest to this study was the confirmation of the significant positive relationship between the rate of 1202 during the initial stages of the supramaximal cycling test (as indicated by Table 1. Anthropometric characteristics of high performance track endurance and sprint cyclists (n = 18) Anaerobic capacity. Anaerobic capacity was assessed as the MAOD according to the procedures of Medbo et al. (1988) during 2 and 5 min of supramaximal cycling. Whilst a pacing strategy was allowed, cyclists were instructed to complete as much work as possible during both tests. During each test the work performed (kJ) was recorded every 10 s. The 02 requirement for the mean power output of each 10-s period was then predicted by linear extrapolation of the individual relationships between VO2 and submaximal power output described above. Subtraction of the 1202 during each test for these 02 requirements yielded the 02 deficit. Heart rate was measured and stored continuously throughout the tests with blood sampling occurring at 1, 2, 5 and 7 min post-test for the determination of peak values of blood lactate concentration and acid-base status. Track testing. A timed, standing start IP4o0o was completed by each cyclist 2 days before the laboratory testing. The IP40o0 was performed on an outdoor 400-m concrete velodrome with cyclists Parameter Mean SD Range Age (year) Height (cm) Mass (kg) Body surface area (m 2) Relative body fat (%) Fat mass (kg) Fat-free mass (kg) Sum of 6 skinfolds (mm) a Sum of 8 skinfolds (ram) b 20.1 179.3 75.30 1.94 9.6 7.30 68.00 54.9 68.1 1.7 3.5 6.00 0.07 1.6 1.70 4.60 10.8 14.8 17.1 - 23.7 173.0 -184.6 65.25- 85.35 1.80- 2.08 6.8 - 12.6 4.55- 10.40 59.90- 77.20 35.4 - 76:4 44.0 - 94.5 * Significant correlation with 4000-m individual pursuit (P< 0.05); a skinfold sites, triceps, biceps, subscapular, suprailiac, front thigh and medial calf; b skinfold sites, triceps, biceps, subscapular, supraspinale, abdominal, mid-axillary, front thigh and medial calf 153 Table 2. Descriptive statistics for maximal oxygen uptake (gOzmax), oxygen response kinetics, cycling economy and anaerobic capacity (n = 18) Table 3. Lactate concentration ([la-]b), power output (W), oxy- Parameter (n=18) Mean SD Range Parameter Maximal oxygen uptake VO2max (1-min-1) 902max ( m l ' k g - i ' m i n -1) V02max (ml.kg-2/3.min -1) 902max ( l ' m i n - l " m -a) 9E . . . . B~s (l'min -1) f~. . . . (beats.min_l) Power output at V02ma~ (W) 5.13" 68.5* 288,2* 2.65* 165.8" 197 0.36 6.4 22.7 0.20 24.1 9 4.58- 5.91 54.4 - 78.5 238.4 -324.2 2.31- 3.00 116.5 -207.6 179 -216 373* 31 314 -447 Oxygen uptake responses kinetics Oxygen kinetics (~-115% 902m~) Oxygen kinetics half time (VO2 tl/2 115% 90amax) Oxygen kinetics (z250 W) Oxygen kinetics half time (V02 tm 250 W) 0.67* 0.12 0.48-- 0.87 27.8* 0.65 4.8 0.08 20.0 - 36.2 0.51- 0.82 26.8 3.3 21.1 - 34.2 0.0 11.6 -18.4 - 23.1 12.9/ 317.8 0.6/ 136.0 12.1 - 14.2/ 124.5 -742.4 0.17/ 4.2 0.01/ 1.7 0.15- 0.19/ 1.51- 8.85 4.65 61.4 4.44 60.2* 0.71 7.3 0.92 12.5 3.00- 5.52 44.3 - 69.4 2.87- 6.51 40.8 - 88.2 Anaerobic capacity MAOD MAOD MAOD MAOD (1)b (ml'kg-1) b (i) ° (ml'kg-1) c 902 .... Maximal oxygen uptake; I?E.... maximal minute ventilation; BTPS, body temperature and pressure, saturated with water vapour; fc..... maximal heart rate; r 115% 1202 . . . . time constant (min) for oxygen response kinetics at 115% 902.m~,; 902 fin 115% VO2 . . . . time (s) to reach one-half of peak VO2 whilst cycling at 115% l~02max; r250 W, time constant (rain) for oxygen response kinetics at 250 W; 9 0 2 hi2 250 W, time (s) to reach one-half of steady-state 9 0 2 whilst cycling at 250 W; MAOD, maximal accumulated oxygen deficit; a cycling economy as determined by method of Van Handel et al. (1988); b determined by supramaximal 2-min protocol; c determined by supramaximal 5-min protocol (n =16); * significant correlation with 4000-m individual pursuit ( P < 0.05) Mean SD Range 0.57 203* 2.70* 105.2" 2.92* 38.8* 1.51" 56.3* 144 72.8 7.414 25.5 0.21 28 0.49 16.2 0.29 5.2 0.16 4.3 11 5.4 0.020 0.9 0.27 - 1.20 150 -260 1.79 - 3.70 75.6 -139.4 2.41 - 3.50 30.6 - 48.7 1.20 - 1.84 48.0 - 64.8 118 -157 61.0 - 80.7 7.369- 7.443 23.6 - 27.4 0.96 30 0.61 18.5 0.34 6.1 0,19 5.4 9 2.5 0.032 2.0 1.35 - 5.03 242 -365 2.71 - 4.91 117.2 -185.4 3.54 - 4.85 43.0 - 64.2 1.77 - 2.46 67.1 - 86.2 154 -187 81.8 - 91.5 7.322- 7.422 18.3 - 26.7 Lactate threshold [la-]b (mmol'1-1) W (W) W. (W-kg -1) .W (W.m -2) VOa (l'min -1) 9 0 2 ( m l ' k g - l - m i n -1) 9 0 2 (l-re. -2) 902 (% V02max) Cycling economy Cycling economy (_+ml.kg-l.min-1) ~ Cycling economy (ml.min-l.W-1; slope/intercept) Cycling economy (ml.kg-l-min-l.W-a; slope/intercept) gen consumption (VO2), heart rate (fo), pH and bicarbonate concentration ([HC03]b) values at the lactate threshold and individual anaerobic threshold blood lactate transition thresholds fc (beats'min -~) fo (%fc .... ) pH [HC03]b (mmol'1-1) Individual anaerobic threshold [la-]b (mmol.1-1) W (W) W (W.kg -1) W (W.m -2) VOz (l'min -1) 9 0 2 (ml'kg-~-min -1) 9Oz (l'm. -2) 9 0 2 (% V02max) fc (beats'rain -1) f¢ (%f~ . . . . ) pH [HCO~-]b (mmol-1-1) * Significant (P<O.05) 2.78 293* 3.88* 151.5" 4.08* 54.1" 2.11" 78.6* 172 87.0 7.367 21.9 correlation with 4000-m individual pursuit Table 4. Descriptive statistics for variables related to the 4000-m individual pursuit. Blood biochemistry was obtained post-test and refers to peak values measured (n = 18) Parameter Mean SD Range Time (s) Speed (km-h -1) Speed (m.s -1) Peak fc (beats. min - 1) Peak fc (%fc . . . . ) [la-]b (mmol'1-1) pH [HC03-]b (mmol'l -~) 339.7 42.5 11.8 194 97.8 10.04 7.141 10.6 14.1 1.8 0.5 9 1.9 1.81 0.072 2.3 314.4 -362.0 39.8 - 45.8 11.0 - 12.7 182 -212 94.3 -100.0 6.20 - 13.33 6.999- 7.286 6.4 - 15.8 For definitions see Table 3 b o t h ~" a n d h a l f t i m e v a l u e s ) a n d IP4ooo p e r f o r m a n c e (r = 0.48). T h e o n l y o t h e r v a r i a b l e r e p o r t e d in T a b l e 2 to c o r r e l a t e s i g n i f i c a n t l y w i t h IP4ooo was t h e r e l a t i v e MAOD determined during the 5-min protocol (r=-0.50). T h e r e was n o s i g n i f i c a n t d i f f e r e n c e in M A O D w h e n a s s e s s e d b y e i t h e r a 2- o r 5 - m i n s u p r a maximal protocol. T a b l e 3 lists t h e m e a s u r e d a n d d e r i v e d v a r i a b l e s rel a t i n g to b o t h t h e Thla- a n d Than,i b l o o d l a c t a t e t r a n s i tion thresholds. All corresponding indices of the two thresholds were significantly different confirming that t w o d i f f e r e n t t h r e s h o l d s w e r e assessed. V a r i a b l e s w h i c h w e r e s i g n i f i c a n t l y r e l a t e d to IP400o w e r e t h e p o w - e r o u t p u t a n d 1202 e x p r e s s e d in all f o r m s , for b o t h thresholds (range r=-0.66 to r = - 0 . 8 6 ) , with the h i g h e s t c o r r e l a t i o n b e l o n g i n g to t h e p o w e r o u t p u t ( W ) at Thla-. M e a s u r e m e n t s r e l a t e d to IP4ooo a r e p r e s e n t e d in T a b l e 4. T r a c k p e r f o r m a n c e s in t h e 4 0 0 0 - m e v e n t v a r i e d b y 47.6 s w i t h o v e r a l l t i m e s b e i n g i n d i c a t i v e o f high p e r f o r m a n c e t r a c k cyclists using r o a d bicycles. A v e r a g e t i m e s w e r e a p p r o x i m a t e l y 60 s o u t s i d e t h e w o r l d record pace. The stepwise multiple regression equations for pred i c t i n g t h e c r i t e r i o n IP4ooo f r o m t h e b e s t w e i g h t e d s u m 154 Table 5. Multiple regression equations for predicting the 4000-m individual pursuit (IP4ooo) from invasive and non-invasive variables Variables Non-invasive me, ~t/02maxa Invasive W~,a, MAOD, Multipleregression equation r SEE (s) IP4ooo= 441..2 + 4.316 x (mr) 25.940 x (VO2max) 0.63 9.1 462.9- 0.366 X (LTPO) -.0.306 x (MAOD) -0.438 x IP40o0 = VO2max b (VQ~ax) complete the IP4ooo by approximately 0.6 s due to added rolling resistance. However, the model of Olds et al. (in press) also predicts that an increase of 2.7 kg in body mass will increase projected IP4000 time by 2.1 s, due to this added mass affecting frontal surface area. In support of the above, it is interesting to note that fat mass (kg) was one of the independent variables selected in the prediction of IP4ooo (Table 5). Maximal oxygen uptake 0.86 5.7 mr, fat mass (kg); VO2maxa, maximal oxygen uptake (1.min-~); VOzmaxb, maximal oxygen uptake (ml-kg-l.min-~); MAOD, maximal accumulated oxygen deficit determined by supramaximal 5-rain protocol (ml.kg-1); V(Th,~,power output at lactate threshold (W); SEE, standard error of the estimate of physiological variables for the cyclists are presented in Table 5. The best overall equation, which included invasive and non-invasive measurements, yielded an r of 0.86 which would indicate that of the total IP4ooovariance of the 18 subjects, 74.0% was accounted for by a linear combination of predictors. The corresponding standard error of estimate was 5.7 s. Discussion Anthropometry The anthropometric profile of this group of high performance track cyclists showed many similarities to results by others using comparable athletes (Craig et al. 1989; McLean and Parker 1989; Neumann 1992; Pyke et al. 1988; Telford et al. 1988, 1990). As is common with almost all high performance athletes, these cyclists have low body fat contents. However, when assembling a profile, it is important to remember that many physiological and anthropometric indices can vary depending upon the particular training phase of the yearly programme. White et al. (1982), in monitoring seasonal changes in body fat of Olympic track cyclists, have reported that one track cyclist decreased his body fat index (sum of four skinfolds) from 28.8 to 22.0 mm even though his body mass increased from 68.9 to 70.2 kg. Longitudinal data collected in our laboratory would indicate that high performance track endurance cyclists consistently achieve body fat contents (sum of six skinfolds, Table 1) below 40 mm the week prior to a World championship or Olympic competition. With respect to track cycling, increased nonfunctional mass has a triple effect in decreasing performance; it increases the energy cost of acceleration, rolling resistance and the projected frontal area of the cyclist (and hence air resistance). In estimating the effect of added mass on an IP4ooo, both Kyle (1991) and Olds et al. (in press) have predicted that a 2.7-kg increment in bicycle and/or cyclist mass will increase the time to With the use of aerodynamic equipment and specialised training techniques, average speeds of 50 k m - h - 1 or greater are now being achieved in the IP4000. According to the results of Di Prampero et al. (1979) and Whitt and Wilson (1983)., cycling at such speeds would require a steady-state VOa ranging from 90 to 100 m.l'kg-l'min -1. Assuming the track cyclist has a VO2max of 76 m l . k g - l - m i n -1, this would mean that he would be operating at approximately 120%-130% 1202max with a concomitantly large contribution from the anaerobic metabolic ' pathways. Thus, a high 1202m~x, together with the ability to achieve it quickly and maintain it, would enable a large, rapid and sustained aerobic energy release and reduce premature reliance upon a large proportion of the finite 02 deficit. Considering the above, and the fact that in the simulated pursuit part of this study the calculated relative contributions of the aerobic and anaerobic metabolic pathways were 84% and 16% respectively, it is not surprising that the indices of ~¢~O2rnax have a high value and are significantly correlated with IP400o ( - 0 . 6 1 - - 0 . 7 9 ) . Moreover, the relationship between power output at 1202max and IP400o would suggest that the maximal exercise intensity that the athlete can achieve during a 1202max test is an important variable predicting athletic potential in this event (Tables 2, 5). The 1202 .... values reported in Table 2 are very similar to previous reports on track cyclists (Burke et al. 1977; Sjogaard et al. 1985; Telford et al. 1990) although they are approximately 10% lower than those reported by Neumann (1992) and Pyke et al. (1988). However, it should be emphasised that our subjects comprised both sprint and track endurance cyclists, with m e a n 1202max values equal to 62.4 and 71.5 m l . k g - l . m i n -1, respectively. Added to this, our subjects were assessed at the end of the transition phase of the yearly training programme, a phase in which the cyclists would be expected to exhibit their lowest VO2max score. Like body fat, 1202max can show significant variation throughout the training year as a result of alterations in the amount of training and its intensity. For example, Sjogaard et al. (1985) have reported changes of up to 22% in the relative VO2m~× of a Danish track cyclist over a 12-month period. Olds et al. (in press) have predicted that a 15% improvement in VO2m~x (5.14--5.91 l'min -1) would enable the track cyclist to complete an IP4ooo approximately 15.5 s faster. 155 Blood lactate transition thresholds There is a scarcity of information in the literature on blood lactate transition thresholds in high performance track cyclists. Telford et al. (1990) have reported the Than,i (power output corresponding to the break point in the blood lactate curve) in Australian male track cyclists to have occurred at 325 W which was slightly higher than the 293 W reported in this study. However, when the track endurance cyclists were considered alone, this value was 303 (SD 30) W and would probably be higher during the specific preparation and competition phase of the training programme. The present study would indicate that whilst the absolute and relative VO2 at Thla- and Than, i were significantly different, they were also strongly related, with the correlation coefficients among the descriptors being at least r=0.51. Added to this were the significant correlations of absolute and relative 1702 at Thla- and Th~n,i with relative 1702m~× (r=0.46 to 0.82). These results are consistent with those reported by Yoshida et al. (1987). Previous studies have reported high correlations between various blood lactate transition thresholds and endurance performance (Jacobs 1986). However, to our knowledge, the significant correlations of Thl,and Than,i indices (Table 3) with IP4ooo are the first to be reported for a short-term, supramaximal aerobic event. Furthermore, the correlation between relative 1702 at Th~- and IP4ooo ( r = - 0 . 8 3 ) was higher than the correlation between relative VOzm,x and IP4ooo ( r = -0.76). This is a similar trend to that reported by Yoshida et al. (1987) and Tanaka and Matsura (1984). Studies by Ivy et al. (1980) and Aunola et al. (1988) have demonstrated that blood lactate transition threshold indices would seem to reflect the muscle metabolic status or peripheral component of the oxygen transport system, VO2max however being closely related to and limited by central mechanisms (Saltin 1985). Thus, considering that 80%-85% of the required energy for a IP4000 was supplied by aerobic metabolism it would seem appropriate that both the central and peripheral components of the aerobic energy system be related to IP4ooo. Finally, the fact that both the central and peripheral components were correlated to IP4ooo has implications with regard to coaching in that the optimal way to train these two components may not necessarily be the same (Saltin 1985). Cycling economy The rationale for assessing cycling economy in these cyclists was that if we assume that the race pace of the cyclists is one that maximally utilises physiological capacities without inducing premature fatigue, then changes (e.g. equipment, training adaptations) that allow the cyclist to use less energy at a given cycling speed should prove advantageous. This would allow a faster cycling speed with the same relative effect on physiological capacities. This rationale is supported by Olds et al. (in press) who have predicted that a 10% improvement in cycling economy would decrease IP4ooo time by approximately 7 s. However, the nonsignificant correlations between cycling economy and performance ( r = - 0 . 1 5 - - 0 . 3 9 ) is in agreement with other studies (Bulbulian et al. 1986; Deason et al. 1991). Despite this, these findings should not be interpreted as meaning than an economical style of cycling is of little importance to IP4o00 performance. The lack of significant correlation was probably due, in part, to the homogeneity of the cycling economy among the cyclists studied (Table 2). This is not surprising since an amount of training in excess of 35000 k m . y e a r - 1 is common for these cyclists. 1702 kinetics At the onset of exercise there is a latency in the attainment of a steady-state 1)'O2 with the time course reported to be influenced by exercise intensity (Hagberg et al. 1978; Whipp and Wasserman 1972), previous priming exercise (Di Prampero et al. 1989), state of training (Hickson et al. 1978; Powers et al. 1985; Zhang et al. 1991), mode of exercise (Cerretelli et al. 1979) and substrate availability (Maassen et al. 1988). Whilst 1?O2 kinetics during sub- and supramaximal exercise have been studied extensively (Hagberg et al. 1978; Hickson et al. 1978; Powers et al. 1985; Whipp and Wasserman 1972), this study was the first to examine the relationship between VO2 kinetics and performance. The half times of 26.8 and 27.8 s for VO2tl/2 250 W and 1?O2~1~2 115% 1?O2. . . . respectively, are consistent with the results of others when performing similar exercise intensities (Hickson et al. 1978; Powers et al. 1985; Yoshida et al. 1992). The nonsignificant difference between the two half times is somewhat surprising as a number of studies have demonstrated that the time required to attain a steady-state 1?O2 is longer at higher exercise intensities load (Hagberg et al. 1978; Hickson et al. 1978; Whipp and Wasserman 1972). However, our results are consistent with Zhang et al. (1991), who have reported no difference in the time to reach 75% of the VO2 response when increasing exercise capacity from 75% to 100%. Furthermore, at least one study has found 1?O2 kinetics were faster as exercise increased above 1?O2m,x (Camus et al. 1985). Other findings of this study were the significant correlations of relative .902 . . . . 1702 at Thla- and Than,i with 1702 tl/a 115% VO2 . . . . These results are consistent with those reported by others (Hagberg et al. 1978; Hickson et al. 1978; Powers et al. 1985; Yoshida et al. 1992; Zhang. et al. 1991), and would support the hypothesis that VO2 kinetics and its improvement may be influenced by both central and peripheral adaptations (Berry and Moritani 1985; Yoshida et al. 1992). The significant correlations between ~- 115% V.'O2max and IP4000 (r=0.48) and 1702h/2 115% VO2max and IP400o (r = 0.48) would support the suggestion that the time to achieve a peak VO2 is important in sporting events requiring the highest rate of energy 156 release over a period of 4-5 min (Thoden 1991). Rapid adjustment of VO2 kinetics during the initial stages of an IP4ooo should be advantageous to performance in two ways; 1. By reducing the reliance upon a proportion of the 02 deficit which could then be spread over a greater time such as that required in a IP4ooo and 2. By reducing early production of lactic acid in the muscles which would otherwise affect the rate of crossbridge cycling and other cellular mechanisms (Hultman et al. 1990). The significant correlations of the supramaximal 1202 kinetic indices with IP4ooo and the proposed associated benefits of having "fast" $702 kinetics, both suggest that IP4oooperformance could be enhanced if VO2 kinetics were trainable. Olds et al. (in press) have mathematically modelled the effect of training or detraining VO2 kinetics on the performance of a IP4ooo. It would.appear that a nominal change of say 7 s for halftime VO2, while all other variables are kept constant, could theoretically affect IP4ooo by about 0.7%. Whilst studies by several groups (Berry and Moritani 1985; Cerretelli et al. 1979; Hickson et al. 1978; Yoshida et al. 1992) have demonstrated the trainability of 1202 kinetics, optimal training regimes and their associated effect on performance have yet to be empirically determined. Anaerobic capacity The existence of a significant anaerobic energy contribution during a sporting event is often indicated by a relatively high postcompetition blood lactate concentration (Saltin 1990). In the IP4o0o under competition conditions, blood lactate concentrations of 11.6 to 22.0 retool-l-1 have been reported (Burke et al. 1981; Neumann 1992; Pyke et al. 1988) suggesting that anaerobic metabolism plays an important role in the required energy production. In support of this, the large M A O D and its significant correlation with IP4ooo ( r = -0.50), when assessed during the 5-min protocol, would seem to imply that anaerobic capacity is an important physiological component for the IP4ooo cyclist. The nonsignificant difference in M A O D when assessed by a 2- and 5-rain supramaximal protocol is consistent with other results (Medbo et al. 1988). However, when expressed relative to body mass, only the 5min M A O D significantly correlated with IP4ooo- Furthermore, when the M A O D results were analysed for the separate groups (sprint and track endurance) the sprint cyclists achieved a significantly higher M A O D in the 2-rain protocol, whilst there was no significant difference in the 2- and 5-min protocol values for the track endurance cyclists. The question of test duration specificity when assessing the M A O D of cyclists specialising in different track events is an important one requiring additional research. The M A O D indices reported in Table 2 are slightly lower than those reported on runners (Medbo and Burgess 1990; Scott et al. 1991), but greater than those reported on elite kayakers (Terrados et al. 1991) and club level road cyclists (Withers et al. 1991). These differences may be in accordance with varying amounts of exercising muscle mass and the stage of the training season. As previously stated, the cyclists in this study were not in peak physical condition and higher values could be expected with specific training (Medbo and Burgess 1990). This lack of peak physical condition, along with equipment and track conditions, would also explain the relatively slow IP4ooo times and low postcompetition blood lactate concentration reported in Table 4. Whilst our highest M A O D value was 88.2 ml.kg-1, Saltin (1990) has suggested that a value of at least 100 ml.kg -1 is a likely estimate for a highly trained IP4o00 cyclist. Olds et al. (in press) have hypothesised the practical benefits of specific anaerobic capacity training by suggesting a 10% increase in M A O D would decrease IP4ooo time by approximately 1 s (12 m). Multiple regression equations The multiple regression equations reported in Table 5 have standard error of estimates of 5.7 to 9.1 s, indicating they may be adequate for the physiological and performance monitoring of an IP4ooo cyclist. Equation 2 in particular, whilst involving an invasive measurement (power output at lactate threshold), would be valuable to the coach and sports scientist as it includes both aerobic and anaerobic metabolic components. 4000-m Individual pursuit The times and speeds presented in Table 4, whilst not world or even national class, are indicative of those by high performance track cyclists when one considers the range of subjects (track endurance and sprint cyclists state to international level), phase of training (end of transition) and conditions (road bikes; 400-m concrete outdoor velodrome). Any question of a lack of subject motivation is eliminated by the fact that there were no significant differences between the peak heart rate (194 vs 193 beats" min-1), blood lactate concentration (10.04 vs 11.21 mmol-l-~), blood pH (7.141 vs 7.121) and blood bicarbonate concentration (10.6 vs 10.1 retool-l-I) of the IP4ooo and laboratory 5-rain simulated individual pursuit, respectively. The lactate concentration and acid-base results reported in Table 4 would also support the contention that a heavy reliance was placed upon anaerobic energy sources during both tests. Finally, the lactate concentrations reported in Table 4 are lower than those reported by Burke et al. (1981) and Pyke et al. (1988). However, this is not surprising as the data of those researchers was collected at a national championship competition. In conclusion, the results of this study would indicate that highly developed aerobic and anaerobic energy systems are necessary to compete successfully in 157 track e n d u r a n c e cycling. I n particular, IP4000 was closely related to VO2max, Thla- and M A O D . This o f course, has c o a c h i n g implications with respect to designing and i m p l e m e n t i n g specialised and o p t i m a l training p r o g r a m m e s . Acknowledgements. This study was supported by a grant from the Australian Sports Commission. 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