Japanese Journal of Physiology, 54, 125–135, 2004

Energetics of Middle-Distance Running Performances in Male and Female Junior Using Track Measurements Véronique L. BILLAT*,‡, Pierre-Marie LEPRETRE*, Anne-Marie HEUGAS†, and Jean Pierre KORALSZTEIN‡ * Faculty of Sport Sciences, University of Evry-Val d’Essonne, Evry, France; † Faculty of Sport Sciences, University of Paris 11, Orsay, France; and ‡ Sport Medicine Center CCAS, Paris, France

Abstract: The aim of this study was to determine the energetic factors of middle-distance running performance in junior elite runners according to gender and by using measurements from on-track performances. Fifteen elite runners (8 males and 7 females) were investigated by means of an incremental test and an all-out run over 600 m performed with a 2-d interval. We calculated (1) the aerobic maximal power (E˙ r max aero, in W kg1), including V˙ O2 max and the delay of attainment of V˙ O2 max in the 600 m run; (2) the anaerobic power (E˙ r max anaero), i.e., the oxygen deficit (J kg1) divided by the duration of the 600 m run. Despite the difference in race duration (87
3 vs. 102
2 s), the 600 m run was made at the same relative value of the velocity associated with V˙ O2 max (vV˙ O2 max) in males and females (121.6
7 vs. 120
8% V˙ O2 max, p0.7). Key words:

E˙ r max aero explained most of the variance in the performance (the personal best performed 8 weeks later) between genders: 65 and 79% over 800 m (T800) and 1,500 m (T1,500). For females, E˙ r max aero explained most of the variance of T1,500 (r 20.66), and E˙ r max anaero improved this prediction (r 20.84). No energetic factor predicted the performance on 800 m run in males. In elite junior athletes, the energetic model with individual data measured over an all-out 600 m performed on a track, provides an explanation for most of the variance in middle-distance running performances between genders. The distinction between aerobic power and anaerobic power allowed an improvement in the prediction of middle-distance running performances. [The Japanese Journal of Physiology 54: 125–135, 2004]

anaerobic, maximal oxygen uptake, gender, adolescence.

Middle-distance running performances (800–1,500 m) relies on both aerobic and anaerobic metabolisms [1]. The relative contribution of each metabolic pathway during a middle-distance run has already been reported in elite athletes, but the performance was for males only performing on a treadmill [2]. Weyand et al. [3] have demonstrated that middle-distance performances depended more on aerobic capacity than on anaerobic capacity. Indeed, Weyand et al. [3] have shown that, in sub-elite runners (2 min 01 s
5 s and 2 min 32 s
6 s over 800 m for males and females), the peak oxygen deficit was a moderately strong predictor of middle-distance performances (38 and 27% of the

variance of the performances over 800 and 1,500 m). Therefore, the energetic factors of performance were expressed with different units: the anaerobic one was reported as capacity (the “anaerobic work capacity” in J), and the aerobic one was expressed as a power (the “maximal aerobic power” in W). Wilkie’s model (see method section) gives a physiological background of the hyperbolic function between the total power output (E˙ r) and the exercise duration. According to Wilkie’s equation of [4], the aerobic and anaerobic factors of performance can be calculated with the same dimension because it allows the aerobic power (E˙ r max aero) to be distinguished from the

Received on December 5, 2003; accepted on February 17, 2004 Correspondence should be addressed to: Véronique L. Billat, Sport Medicine Center CCAS, Paris, France, 2 Avenue Richerand, F-75010 Paris, France. Tel: 33–1–42–02–08–18, Fax: 33–1–42–39–20–83, E-mail: [email protected]

Japanese Journal of Physiology Vol. 54, No. 2, 2004

125

V. L. BILLAT et al.

anaerobic power (E˙ r max anaero) to help understand how human athletes produce power in mid-distance events. This has been validated for middle-distance running performances by di Prampero et al. [5]. However, this study [5] included in Wilkie’s model, standard values for maximal anaerobic capacity and a V˙O2 max, which were measured on a cycle ergometer or on a treadmill while the performance and the energy cost of running were measured on the track. It is well known, however, that V˙O2 max is lower in cycling compared with a running exercise [6] and that the energy cost of running on a treadmill is not similar to running on a track [7, 8]. Since this study was performed 10 years ago [5], technological progresses have made it possible to measure all the factors in field experiments by using breath-by-breath portable oxygen analyzers [8–13]. Elite athletes, who generally are not available for testing in laboratory conditions, are often more open to field tests. The first purpose of this study was to carry out all the measurements in the field, which is a positive factor because previous studies have examined only predictor variables in the laboratory. If it is agreed that females have a lower aerobic power than males (ml O2 kg1 min1) [14], this is less reliable concerning the anaerobic work capacity [7, 15, 16]. A significant difference was reported between trained male and female adolescents [17]. Naughton et al. [17] have reported that the maximal accumulated oxygen deficit (MAOD) in trained 14-year-old adolescents (male and female national level badminton players) was lower in females (53.2 ml kg1) than in males (68.6 ml kg1). This was not so in a study performed on adult high-level male and female middle-distance runners (49 and 40 ml kg1 for the males and females, respectively, p0.05) [7]. However, this last study was performed on a treadmill, and no studies have compared the anaerobic work capacity between genders on the track in elite athletes. This possible difference of E˙ r max anaero between genders should also contribute to the lower power output value on middle-distance running and thus to, the lower performance over 800 and 1,500 m. Since males and females ran over the same distance and for psychological reasons the athletes did not want to be tested on the full racing distance, we chose in agreement with the national team coaches to test them over an all-out 600 m run. We were aware that the same distance would take longer for females than for the males and that it could have an impact on the anaerobic work capacity. However, the purpose of this study was to compare the influence of the aerobic and anaerobic powers on performance. Thus the anaerobic power depends on the anaerobic capacity and also on 126

the run duration. Therefore, the aim of this study was to analyze the variance in performance, by examining the partitioning of metabolic power into aerobic and anaerobic components over a 600 m maximal run on the track according to gender, in junior elite male and female middle-distance runners. METHODS

The subjects were 15 middle-distance runners (8 males and 7 females), all members of the French national junior team, who had volunteered to participate in this study. Their individual physical characteristics and performances are given in Table 1. Before participation, all subjects were informed of the risks and stress associated with the training program, and were asked to provide a written voluntary informed consent in accordance with the guidelines of the Hospital Saint Louis of Paris. Experimental design. The tests were performed in March before the competition period during a national training camp in the southern France. All tests were performed on a synthetic 400-m track in a climate of 16 to 18°C without wind (2 m/s, anemometer, Windwatch, Alba, Silva, Sweden). The tests were performed by each runner at the same hour of the day, with a 2-d interval. The subjects performed (1) an incremental test to determine maximal oxygen uptake (V˙O2 max); the velocity associated with the attainment of V˙O2 max (vV˙ O2 max); the velocity at the lactate threshold (vLT); the energy cost of running (Cr); and (2) an all-out test over 600 m to determine the time over that distance (T600). This test was performed like a competition, and the athletes ran three by three (one female group) or four by four (one female group and two male groups). For both tests, each subject was instructed by the coaches and encouraged to give their maximum efforts. The tests were performed by a given subject at the same time of day, in a climatecontrolled environment. All test sessions were carried out on a 400-m covered synthetic track. Throughout the incremental test, the subjects adopted the required velocity by use of an audio-visual system. This system included guide marks set at 25-m intervals along the track (inside the first lane), and audio signals to determine the speed needed to cover the intervals. The velocity of locomotion was strictly controlled throughout the tests with photoelectric cells set every 50 m (Brower Timing Systems, Salt Lake City, UT). Procedures. Throughout the two tests, the respiratory and pulmonary gas exchange variables were measured by a breath-by-breath portable gas analyzer

Japanese Journal of Physiology Vol. 54, No. 2, 2004

Energetics in Middle-Distance Running

(Cosmed K4b2, Cosmed, Rome, Italy), which was calibrated before each test according to the manufacturer’s instructions [12, 13]. The device weighs 800 g and was placed near the center of mass of the body. Breath-by-breath data were later reduced to 30 s (for the incremental test) and to 5 s (for the all-out test on 600 m) stationary averages (Data Management Software, Cosmed, Rome, Italy). Fingertip capillary blood samples were collected into a capillary tube, and analyzed for lactate concentration by the use of a Doctor Lange lactate analyzer (Lange GmbH, Berlin, Germany). This lactate analyzer was calibrated before the tests with several solutions of known lactate concentrations. The subjects first performed an incremental test in 3-min stages. The initial velocity was set at the average velocity maintained over 3,000 m, which has been described as being close to the velocity associated with V˙O2 in an incremental test (vV˙ O2 max) minus 6 km h1, so that the exhaustion occurs within 20 minutes for each subject [7]. The velocity increments between the stages were set at 1 km h1. All stages were followed by a 30-s rest. During this period, a fingertip capillary blood sample was collected. Other fingertip samples had been collected before, immediately after the end of the test and at last 3 min after the end. V˙O2 max was defined as the highest 30-s oxygen uptake value reached during this incremental test, with a respiratory exchange ratio (RERVCO2 max/V˙O2) greater than 1.05, blood lactate greater than 8 mM, and a peak heart-rate at least equal to 90% of the age-predicted maximum. vV˙ O2 max was defined as the minimal velocity at which V˙O2 max occurred [3]. When vV˙ O2 max was maintained for half, and not all the last stage, it was considered to be the median velocity maintained during the last final two stages [10]. vLT was defined as the velocity for which an increase in lactate concentration corresponding to 1 mmol l1 occurs between 3.5 and 5 mmol l1 [18]. vLT was determined by two independent reviewers. The net energy cost of running Cr is defined as the energy required above resting (estimated by V˙O2 V˙O2 rest) to transport the subject’s body over one unit of distance [5]. Cr(V˙O2V˙O2 rest)/v

(1)

Where V˙O2 is the oxygen uptake at velocity v and is expressed in ml kg1 min1; V˙O2 rest is the V˙O2 at rest and is assumed to be equal to 5 ml kg1 min1, according to the intercept of the V˙O2-speed regression line obtained by Medbo and Tabata [19]; v is in m min1, and Cr is in ml kg1 m1. Therefore Cr is estimated by the oxygen uptake at a submaximal speed (vLT) at

which the anaerobic metabolism part of energy yielded is negligible and at which there are no slow kinetics of oxygen uptake [5]. The energy cost of running is independent of the speed until it reaches 20 km h1 [5]. Therefore we estimated the energy cost of running from the rate of oxygen uptake, which was averaged between the second and third minutes of the stage run at an intensity of 1 km h1 below the lactate threshold velocity (vLT) [7]. Throughout this paper, Cr is expressed in J m1 on the assumption that 1 ml O2 consumed in the human body yields 20.9 J (which is strictly true only if the RER equals 0.96) [20]. The subjects subsequently performed an all-out test over 600 m to determine the time over this distance (T600). After a 25-min warm-up period at 60% vV˙ O2 max followed by two 100 m runs at a faster pace (17 s for females and 15 s for males) and a 5-min rest period, the subjects were instructed to run as fast as possible over a distance of 600 m. As for the incremental test, a fingertip blood sample was collected before the test, immediately after the end of the test and at last 3 min after the end. A lap time was taken every 200 m to focus on the speed variation during this free-pace exhaustive 600 m run. AO2 deficit calculation. The accumulated oxygen deficit (AO2 deficit) was calculated as the difference between the AO2 demand and the AO2 uptake (both in ml kg1) measured during the 600 m run. The AO2 demand was estimated by means of the following equation: AO2 demandv600(V˙O2 at vLT1)/(vLT1)

(2)

Where v600 is the velocity over 600 m (600/T600) and vLT1 is the velocity at the lactate threshold minus 1 km h1. The speeds are expressed in km h1 and V˙O2 is expressed in ml kg1 min1. The AO2 deficit calculated for the 600 m run which was performed at supra-maximal speed (120% of vV˙ O2 max) close to the intensity recommended in cycling by Medbo et al. [19, 21] and then applied by numerous studies and has been extensively used [16, 22–24]. However, this AO2 deficit was not considered as the “maximal AO2 deficit” (MAOD), since it was slightly shorter than 2 min (especially for the males). The percentage of the anaerobic contribution in the 600 m was calculated with the following equation: % ANAE(AO2 deficit/AO2 demand)100 (3) Thus, the percentage of the aerobic contribution over 600 m was equal to 100%ANAE. Oxygen uptake kinetics. The breath-bybreath oxygen uptake data were reduced to 5-s stationary averages. These data were then smoothed by the

Japanese Journal of Physiology Vol. 54, No. 2, 2004

127

V. L. BILLAT et al.

use of a 3-step average filter to reduce the noise, thus enhancing the underlying characteristics (Data Management Software, Cosmed, Rome, Italy). These data were finally fitted to a mono-exponential model [5] that use an iterative non-linear regression by Sigma Plot Software (SPSS, Chicago, IL, USA): V˙O2(t)A0A1[1exp((tTD1)/t 1)]

(4)

Where A0 is the baseline value (ml min1), A1 is the asymptotic amplitude for the exponential term (ml min1), t 1 is the time constant (s), and TD1 is the time delay from the onset of exercise (s). The model of energetics in middle-distance running is in accordance with the model of di Prampero [5]. First, we calculated the metabolic power (E˙ r) [5] for running 600 m at speed v: E˙ rCr600/T600

(5)

E˙ rCrv600

(6)

Where Cr is expressed in J kg1 m1 and 600 is the distance in meters and T600 is the time needed to achieve the distance of 600 m, v600 is then in m s1 and E˙ r is in W kg1. Cr is determined for running at a constant speed. However, because maximal performances in track running are performed from a stationary start, the overall energy cost, inclusive of the energy spent to accelerate the body from zero to final speed (Cr,tot, J m1 kg1) [5] is given by: Cr,totCr(0.5Mv21d1)M1

(7)

Where M is the mass of the subject, d is the distance run and  is the efficiency of transformation of metabolic energy into kinetic energy. The latter can be assumed to be 0.25, since in the initial acceleration phase no recovery of elastic energy can take place; therefore the overall running efficiency must approach the efficiency () of muscular contraction [5]. If  is assumed to be equal to 0.25 (25%), Eq. 7 reduces to: Cr,totCr2v2d1

(8)

We then calculated the maximal metabolic power [5] of the runner: E˙ r maxAnSte1MAPMAPk1 (1exp(kte))te1

(9)

Where AnS is the maximal amount of energy released by anaerobic (lacticalactic) sources and MAP is the subject’s maximal aerobic power, k is the velocity constant at which V˙O2 max is attained at the onset of exercise and k1/t . At the end, we can write Eq. 9 as follows: 128

E˙ r maxAnSte1MAPMAP t (1exp(kte))te1

(10)

The third term of Eq. 10 is because V˙O2 max cannot be instantaneously reached at the onset of work. Therefore Eq. 10 allows a calculation of E˙ r max on which the runner can rely as a function of the time run called the exhaustion time, te, provided that the subject’s AnS and MAP are known. AnS was replaced by an AO2 deficit and MAP by V˙O2. The time to exhaustion (te) was T600. We then distinguished the first and second terms of the right side of equation 10: E˙ r max anaero (the oxygen deficit in J kg1 divided by te) from E˙ r max aero (V˙O2 max in W kg1 balanced by the delay of attainment of V˙O2 max). Therefore E˙ r max aero MAPMAPk 1 (1exp(kt e ))t e –1 , and so E˙ r max anaeroAnSte1. Two months after this 600 m-test, the athletes achieved their personal best over 800 and 1,500 m. During these two months, the athletes undertook highintensity training runs based on interval training set at speeds at and above vV˙ O2 max [25]. Because these elite athletes were not available for testing during the period of competition, we calculated the speed over 600 m that the runners would have been able to run during the period of competition in order to estimate their progress. This was estimated from their performances over 400, 800, and 1,500 m according to the speed-race distance relationship proposed by di Prampero et al. [5]. We verified that all subjects decreased their times over 600 m (i.e., improved their performance) in a homogenous way (coefficient of variation less than 15%). Anthropometry. Height and weight were measured. Five skin-fold measurements were made (triceps, biceps, suprailiac, subscapular, midthigh) and percent of body fat calculated by using the formula of Durnin and Womersley [26]. Statistics. Because of the small sample size in this study (n7 and 8), the normality of the distribution and the equality of the variances were checked by SigmaStat (Jandel, Chicago, IL, USA). We performed an analysis of variance (ANOVA) test at one factor (gender) to measure the gender effect on each parameter of the energetic model for middle-distance running (Staview 5.5, Statsoft, Berkeley, CA, USA). A stepby-step regression (F to enter4) was used to determine the factor of performance over 800 and 1,500 m. The correlations between the bioenergetic parameters and between E˙ r and E˙ r max were determined by use of the Pearson product moment correlation coefficient. The level of significance was set at 5% ( p 0.05). All results are presented as means
SD.

Japanese Journal of Physiology Vol. 54, No. 2, 2004

Energetics in Middle-Distance Running Table 1. Individual physical characteristics of runners and performances by males and females and metabolic power required to run 800 and 1,500 m at their personal best.

Subjects

Weight (kg)

Height (cm)

Age (years)

Fat mass (%)

Metabolic power required at their best performance (W kg1)

Time (s) Over 800 m

Over 1,500 m Over 800 m

Over 1,500 m

Males 1 2 3 4 5 6 7 8 Mean SD

72 63 63 69 62 51 56 57 62 7

184 179 180 184 178 171 180 175 179 4

19 18 18 19 19 19 18 19 18 1

10.0 7.4 10.0 11.5 9.3 7.0 8.0 9.0 9.0 1.5

108.3 109.9 117.4 108.8 109.6 114.0 115.0 117.0 112.5 3.8

236.4 241.9 246.0 237.0 229.3 231.0 225.3 235.0 235.3 6.7

30.4 29.4 29.3 30.7 30.0 30.9 33.6 27.4 30.2 1.8

26.1 25.0 26.3 26.4 26.9 28.6 32.2 25.6 27.1 2.3

Females 1 2 3 4 5 6 7 Mean SD

54 55 53 56 51 45 53 52 4

168 174 167 164 158 161 172 166 6

17 18 19 19 19 18 19 18 1

17.8 17.3 20.6 21.0 22.0 16.0 17.0 18.8 2.3

127.8 126.6 129.0 130.3 132.0 130.0 126.5 128.9 2.0

271.0 270.0 257.2 269.0 271.2 269.5 262.7 267.2 5.3

25.8 26.9 26.0 28.8 26.5 28.8 27.8 27.2 1.3

22.8 23.7 24.5 26.1 24.2 26.1 25.1 24.6 1.2

RESULTS

Despite the difference in run durations (T600) between genders (86.5
2.8 vs. 101.6
2.0 s), the 600 m was run at the same relative value of vV˙ O2 max and at the same lactate threshold velocity in males and females (121.6
7 vs. 120
8% V˙O2 max respectively, p0.70 and 138.4
6.0 vs. 139.2
12.9% vLT, p0.73, in males and females, respectively) (Table 2). Moreover, the coefficient of variation of the speeds between the three succesive 200 m of the 600 m run was homogenous within these elite middle-distance runners and not significantly different between gender (6.1
0.5 vs. 5.6
0.4% for males and females, respectively, p0.06). The increase in V˙O2 during the all-out 600 m fit a monoexponential model with a time constant that was not significantly different between males and females (24.7
11.5 vs. 31.9
12.0 s, p0.27, respectively). During the 600 m run, males and females elicited 99.3
1.9 vs. 100.5
2.9% of V˙O2 max (p0.08) and all subjects reached at least 97% of V˙O2 max. The time constant for oxygen kinetics was not correlated with the performance over the 600 m (r0.09, p0.76, n15). The initial oxygen deficit (i.e. before the at-

tainment of V˙O2 max) accounted for 58.5
13.0 and 56.8
14.0% of the AO2 deficit in males and females, respectively ( p0.80). The relative contribution of the anaerobic metabolism to the energy spent over the 600 m was not significantly different between genders (38.2
12.3 and 41.5
12.3% for males and females respectively, p0.62) (Table 3). Females had more than twice the body fat mass of males (18.8
2.3 vs. 9.0
1.5%) (Table 1). The body fat mass explained 78% of the variance of T600 and 80% of the variance of T800 and T1,500 performances between genders, but not significantly within genders. Indeed, if males had a higher V˙O2 max than females (71.4
3.0 vs. 60.5
5.1 ml kg1 min1, p0.001), this difference was not more significant when the maximal aerobic power was expressed by kg of lean body mass (78.5
3.1 vs. 74.6
6.0 ml kg1free fat mass min1, p0.13, Table 2). The individual aerobic and anaerobic capacities of the males and females are indicated in Table 2. In contrast to the maximal oxygen uptake, the anaerobic capacity was not significantly different between males and females (45.5
14.9 vs. 52.1
16.4 ml kg1, p0.42 and 50.0
16.0 vs. 64.2
20.5 ml kg1free fat mass, p0.15, Table 2). There was also no significant difference in

Japanese Journal of Physiology Vol. 54, No. 2, 2004

129

V. L. BILLAT et al. Table 2.

Aerobic and anaerobic capacities of the males and females. Free fat Lactate V˙ O2 max (ml (%v V˙O2 max) maxincr (mM) kg1 free fat mass min1)

V˙ O2 max (ml kg1 min1)

v V˙O2 max (km h1)

HRmax (bpm)

Males 1 2 3 4 5 6 7 8 Mean SD

73.0 69.7 71.0 69.8 71.8 75.0 75.0 66.0 71.4 3.0

21.5 20.5 20.0 20.5 21.5 21.5 21.5 20.5 20.9 0.6

203 199 204 199 200 199 199 199 200 2

88.4 85.4 90.0 85.4 81.4 88.4 86.1 87.8 86.6 2.7

12.7 14.2 12.1 11.4 13.7 12.0 15.0 16.0 13.4 1.6

Females 1 2 3 4 5 6 7 Mean SD

57.4 57.5 66.5 54.4 58.0 62.0 68.0 60.5 5.1

17.0 17.0 19.0 16.0 18.5 18.0 19.0 17.8 1.1

199 200 194 204 190 202 196 198 5

88.2 85.3 86.8 81.3 86.5 86.1 89.5 86.2 2.6

12.0 11.9 11.9 13.2 15.0 14.0 13.0 13.0 1.2

Subjects

v600 (%v V˙O2 max)

AO2 deficit (ml kg1)

81.1 75.3 78.9 78.8 79.2 80.7 81.5 72.5 78.5 3.1

117.8 121.0 126.6 122.7 118.3 137.6 114.8 113.8 121.6 7.7

60.3 30.0 36.4 41.1 33.1 60.6 67.4 35.2 45.5 14.9

69.8 69.5 83.8 68.9 74.4 73.8 81.9 74.6 6.0

125.9 125.1 112.3 133.1 112.3 115.4 116.0 120.0 8.1

61.2 41.4 25.2 76.0 46.3 53.4 61.5 52.1 16.4

vLT

V˙ O2 max, maximal oxygen uptake achieved in the incremental test; v V˙O2 max, velocity associated with V˙ O2 max in the incremental test; vLT, velocity associated with the lactate threshold in the incremental test; Lactate max, maximal blood lactate accumulation measured at the end of the incremental test; Free fat V˙ O2 max, V˙ O2 expressed in ml O2 kg1 of free fat mass min1; v600, average velocity over the 600 m run expressed in percentage of v V˙O2 max; AO2 deficit, the accumulated deficit measured in the all-out run over 600 m (at 121.1% of v V˙O2 max on average).

the energy cost of running between genders (Table 3). We then examined the role of the aerobic and anaerobic power output in performance. After investigating these classical factors of performance used in previous studies, we focused on those provided and adapted from Wilkie’s model [4]: the maximal metabolic power (E˙ r max) and the aerobic and anaerobic power outputs (E˙ r max aero and E˙ r max anaero). We first made sure that the energetic model proposed by Wilkie (4) worked with all the measurements collected on the track. This was the case because there was no significant difference between the total power output on the 600 m run (E˙ r) and the maximal metabolic power (E˙ r max) among the 15 subjects (1.74
3.1 vs.1.72
0.45 kW for E˙ r and E˙ r max, t0.18, p0.86) or among males and females (E˙ r1.98
0.20 vs. 2.00
0.41 kW, t0.17, p0.87 in males and 1.47
0.11 vs. 1.39
0.17 kW, t1.12, p0.28 in females). For an easier comparison between the genders, E˙ r and E˙ r max are also indicated in Table 3 by kilogram of body weight. There was a significant correlation between E˙ r and E˙ r max for the whole group 130

(r0.869, p0.0001, Fig. 1). The power output (E˙ r) equaled 1.98
0.20 vs. 1.47
0.11 kW in males and females, respectively, and was significantly different between genders because males ran faster than females with the same energy cost of running. Furthermore, when E˙ r was expressed by kg of body weight it remained significantly higher for males (32.1
2.3 vs. 28.1
1.3 W kg1, p0.01) but not when expressed by kilogram of lean body mass (32.3
2.2 vs. 31.9
1.7 W kg1free fat mass, p 0.69) (Table 3). Similarly, the maximal metabolic power over 600 m (E˙ r max) was significantly higher in males than in females in absolute value (2.00
0.41 kW vs. 1.39
0.17 kW, p0.01) and relative value to body mass (32.3
4.5 vs. 26.4
2.2 W kg1, p0.01). This was no longer so when E˙ r max was expressed by kilogram of lean body mass (35.3
2.4 vs. 34.6
1.7 W kg1free fat mass, p 0.53). This is in accordance with when they were expressed by kg of lean body mass, V˙O2 max and AO2 deficit were not more significantly different between genders. The aerobic and anaerobic power outputs

Japanese Journal of Physiology Vol. 54, No. 2, 2004

Energetics in Middle-Distance Running Table 3.

E˙ r is the metabolic power required in the 600 m run for males and females. E˙ r max (W kg1)

E˙ r (W kg1)

E˙ r max aero (W kg1)

Males 1 2 3 4 5 6 7 8 Mean SD

30.3 32.9 40.3 34.2 36.2 28.5 30.1 26.1 32.3 4.5

31.2 30.3 32.9 31.6 31.8 34.7 36.0 28.7 32.1 2.3

25.5 24.4 24.8 24.4 25.1 26.2 26.1 23.1 25.0 1.1

15.5 12.5 19.2 15.4 15.6 14.3 12.0 7.5 14.0 3.5

51.3 25.7 29.6 34.4 28.2 57.6 48.8 30.5 38.2 12.3

Females 1 2 3 4 5 6 7 Mean SD

24.7 28.6 30.1 25.6 26.2 24.4 24.8 26.4 2.2

26.7 27.3 27.1 29.8 27.4 29.4 29.0 28.1 1.3

20.1 20.1 23.2 19.0 20.3 21.7 23.8 21.2 1.8

12.7 12.3 10.7 13.7 10.7 8.6 9.7 11.2 1.8

52.1 33.8 21.0 56.8 37.1 40.1 49.5 41.5 12.3

Subjects

E˙ r max anaero Anaerobic Time over (W kg1) contribution (%) 600 m (s)

Cr (J kg1 m1)

t (s)

85.3 87.1 85.3 85.9 84.9 83.0 87.5 92.6 86.5 2.8

4.12 4.03 4.31 4.18 4.12 4.41 4.83 4.01 4.25 0.27

41 15 13 20 15 40 33 21 25 12

100.9 101.6 101.2 101.4 104.0 104.0 98.0 101.6 2.0

4.12 4.26 4.20 4.68 4.37 4.68 4.39 4.39 0.22

46 19 17 41 25 29 46 32 13

E˙ r max, maximal metabolic power of the subjects during the 600 m all-out run; E˙ r max aero and E˙ r max anaero, maximal aerobic and anaerobic powers calculated from the model of Wilkie [4]; Cr, energy cost of running. The anaerobic contribution is the percentage of the energy spent over 600 m yielded by the anaerobic metabolism. t is the time constant of oxygen kinetics during the 600 m run.

Fig. 1. Relationship between the metabolic power (E˙ r) required during the all-out 600 m run and the maximal metabolic power (E˙ r max) produced over the all-out 600 m run.

(E˙ r max aero and E˙ r max anaero) were considered separately from E˙ r max. E˙ r max aero was significantly higher in males than in females even when expressed by kilogram of body mass (25.0
1.0 vs. 21.2
1.8 W kg1, p0.001) in contrast with E˙ r max anaero (14.0
3.5 vs. 11.2
1.8 W kg1, p0.08) (Table 3). However, E˙ r max aero was no longer significantly different between genders when it was expressed by kg of lean body mass (27.4
1.1 vs. 26.1
2.1 W kg1free fat mass, p0.13) and this was always true for E˙ r max anaero (15.4.0
3.9 vs.

13.8
2.4 W kg1free fat mass, p0.37). After having focused on the energetic characteristics of each gender, the ability of E˙ r max aero and E˙ r max anaero to explain the variance in performance over 800 and 1,500 m was examined. Since the energetic characteristics of the subjects were collected during this 600 m run we examined the correlation between the time over 600 m and the performance over 800 and 1,500 m (performed eight weeks later in competition). The time over the 600 m–test run was correlated with the time over 800 m achieved two months later during the competition for all runners and for females (r0.88, p0.001, n15 and r0.78, p0.04) but not for males (r0.10, p0.81). T600 allowed a very rough prediction of the performance over 800 m between genders and within males but more accurately within females (at a level of accuracy of 4.0 and 1.4 s or males and females, respectively). T600 was correlated with the time over 1,500 m for the entire 15 runners (r0.88, p0.001, n15) but not considering each group of genders separately (r0.51, p0.26 for females and r0.20, p0.69 for males). The runners performed their personal best over 800 m at an average velocity representing 101
7 and 105
71% of the velocity over 600 m performed in the test (for males

Japanese Journal of Physiology Vol. 54, No. 2, 2004

131

V. L. BILLAT et al. Table 4. Step-by-step regressions between the performances over 800 and 1,500 m among all the runners and gender groups. Runners and racing distances

Variables

r2

Regression equation

Residual (s)

All subjects over 800 m (N15)

E˙ r max E˙ r max aero (W kg1) E˙ r max aero (W kg1) Cr (J kg1 m–1)

0.58 0.65 0.74

T800146.4615.35E˙ r max T800189.933.01E˙ r max aero T800140.162.89E˙ r max aero 10.87Cr

1.66 1.52 1.41

All subjects over 1,500 m (N15)

E˙ r max aero (W kg1)

0.79

T1,500400.596.49E˙ r max aero

2.31

Females over 1,500 m (N7)

E˙ r max aero (W kg1) E˙ r max aero (W kg1) E˙ r max anaero (W kg1)

0.66 0.84

T1,500318.092.41E˙ r max aero T1,500366.211.80E˙ r max aero 3.73E˙ r max anaero

1.50 1.29

E˙ r, metabolic power required in the 600 m run; E˙ r max, maximal metabolic power of the subjects in the 600 m all-out run; E˙ r max aero and E˙ r max anaero, maximal aerobic and anaerobic powers calculated from Wilkie’s model [4]; Cr, energy cost of running. Anaerobic contribution is the percentage of the energy spent over 600 m yielded by the anaerobic metabolism.

and females, respectively, p0.16). Furthermore, the 800 m run during the competitive period was not only faster than the 600 m run, but also longer, 33
10 and 27
2% in males and females, respectively (p0.17). This corresponds to a new performance over 600 m improved by 4.2
5.9 and 7.2
1.5 s for males and females (p0.19). In contrast with E˙ r max, E˙ r max aero and E˙ r max anaero explained most of the performance in middle-distance running. Indeed, E˙ r max aero explained 65% and 79% of the variance of T800 and T1,500 (predicting the performance at the nearest 1.5 s and 2.3 s, respectively) (Table 4). When Cr was added to E˙ r max aero these two factors explained 74% of the variance of T800 (Table 4). However, Cr gave no additional accuracy in the prediction of the variance of T1,500. Within gender, but for females only, E˙ r max aero explained 66% of the variance of T1,500 and 84% when it was combined with E˙ r max anaero (Table 4). For males, no energetic factors allowed a prediction of the 800 and 1,500 m performance. DISCUSSION

The purpose of this study was to determine the energetic factors of middle-distance running performance in junior elite runners according to gender and using measurements performed on a track during a 600 m all-out run. All subjects reached V˙O2 max during their 600 m-run in accordance with previous data, which showed that subjects reached V˙O2 max even on a 400 m all-out run [10, 27]. The results showed that the aerobic power was the main performance factor between gender and within females. However, the anaerobic 132

power allowed an improvement in the prediction of performance within gender, but for females only. No energetic factor allowed a prediction of performance within males. The aerobic power (expressed by kg of lean body mass) was higher for males, but not the anaerobic power. The energetic specificity of the 600 m run and its ability to estimate the anaerobic power. The present study confirms that Wilkie’s model [4] allows the calculation of maximal power from the experimental data obtained on the track during an incremental test (V˙O2 max) and during an all-out test of more than 600 m (E˙ r max). We used this model to calculate aerobic and anaerobic power, taking into account the duration of exercise and therefore avoiding the use of a different dimension for both metabolisms, i.e., a capacity and a power-output for the anaerobic and aerobic metabolisms, respectively. During this allout 600 m run, the relative contribution of the anaerobic energy system during the event in males (38%) was rather low compared to the value (44%) reported by Spencer et al. [1, 2], even over a longer distance such as 800 m. This difference could be due to the subjects being older (21
3 vs. 18.6
0.5 years), but their personal bests were close: 1 min 50
0:02 s vs. 1 min 52
0:03 s for Spencer et al. [2] and the present study, respectively. Therefore this difference may be because in our study the athletes were still far from their personal best. This will be discussed further. No data are available in the literature examining the aerobic and anaerobic contributions in mid-distance events for female athletes. We found no significant difference according to gender in the anaerobic metabolism contribution over 600 m. This similitude of the energetic

Japanese Journal of Physiology Vol. 54, No. 2, 2004

Energetics in Middle-Distance Running

balance over 600 m in males and females is in accordance with males and females running at the same fraction of vV˙ O2 max (120%) which is surprising in regards to the shorter run duration for the males compared with the females (86 vs. 101 s). Despite this shorter 600 m run duration for the males, their anaerobic power was not significantly different compared to the females. In contrast with world-level 400 m-runners who reached their maximal oxygen deficit at 400 m [27], our mid-distance runners did not tax their maximal accumulated oxygen deficit over 600 m. Indeed, the anaerobic capacity measured in the 600 m (45 and 52 ml kg1 for our males and females) was much lower than the standardized value proposed by di Prampero et al. [5] to validate Wilkie’s model for middle-distance running. Indeed, di Prampero et al. [5] took the value of 68 ml kg1 as reference to the highest value of anaerobic capacity for human beings at the ages of 19 and 17 years. Therefore the accumulated oxygen deficit obtained for the males in this study was only 73% of this referenced anaerobic capacity [5], but reached 93.0% for the females. The values of time constant for oxygen kinetics which determine the delay for the attainment of V˙O2 max were in the range of those measured on a treadmill or in field conditions among older athletes of the same level for lower and similar intensities [10, 25] (t 24 and 31 s for males and females, but with a coefficient of variation of 30%). Indeed, this value is in accordance with that reported by di Prampero et al. [5] (30 s of interval from rest to work). Endurance training accelerates the oxygen kinetics (and so decreases the initial oxygen deficit) [28]. If our results reported a low accumulated oxygen deficit for the males, this value is nevertheless in accordance with those previously measured in elite middle -distance runners [7, 29]. Furthermore studies [7] performed in elite middle-distance runners showed no gender effect on oxygen deficit (49 and 40 ml kg1 for the males and females, respectively, p0.05) [3]. More recently, Weber and Schneider [16] have demonstrated a lower maximal accumulated oxygen deficit (14%) in females vs. males. This difference remained the same after 4 weeks of high-intensity interval training performed 3 times per week from 82–100% of the power used to estimate MAOD before training (i.e., 100–120% V˙O2 max) [16]. To confirm that there is no gender effect on the accumulated oxygen deficit, we can suggest that females must be tested over 600 m and males over 700 m to make both genders run more than 2 min, which is the exercise duration recommended by Medbo and Tabata for measuring MAOD [19]. For this duration they estimated the contribution

of the anaerobic metabolism as being 35% of the energy needed for an all-out cycling-exercise lasting 2 min on the field, which is, however, not dissimilar from the data we obtained over the 600 m even for the males. Indeed, the aerobic and anaerobic powers measured over 600 m explained the variation in performance between genders and within females, but not within males. We found higher values of maximal power output (E˙ r max) in males than in females. This was due to the highest maximal aerobic power in males and even when the aerobic power is expressed by kg of lean body mass [14]. However, this was not so for the anaerobic power, which brings some new insights to the debate of the gender difference concerning the anaerobic work capacity that did not take the exercise duration into account [7, 16]. Therefore the main factor that explains the difference in performance between genders is the maximal oxygen uptake. This is in accordance with Weyand et al. [3], who reported that this peak oxygen deficit was the strongest metabolic predictor of 100-, 200-, and 400-m performance and that V˙O2 peak was the strongest metabolic predictor of T800 and T1,500. Furthermore, because V˙O2 max relative to the lean body mass was not significantly different between genders, we can estimate that fat mass is the determinant factor in the difference in performance between genders. This is confirmed by the direct relationship between performance and fat mass when both genders are considered. In our study, E˙ r max aero was the main predictor not only of T800 and T1,500 between genders, but also for T1,500 for the females. The important original feature of that present study is that for females, E˙ r max anaero improved the prediction of performance over 1,500 m. This could be due to the greatest heterogeneity of E˙ r max anaero in females because of their differences in training programs. In males, no energetic parameter was a major performance factor over these distances and this is probably due to the inadequacy of the 600 m run to estimate the maximal oxygen deficit and maybe they had not yet followed an intensive training program performed at a speed higher than vV˙ O2 max [25]. Indeed, two months later these mid-distance runners ran in official races of 800 m. During this occasion they were able to run 1 and 5% faster for a 30% longer exercise duration than on the 600 m performed 2 months earlier. We therefore calculated that they would have improved their performance over 600 m by 5
7 and 7
1% for males and females (p0.37) which is in the range of the effectiveness of such training [8, 10]. This means that it might be possible to improve this prediction much more in middle-dis-

Japanese Journal of Physiology Vol. 54, No. 2, 2004

133

V. L. BILLAT et al.

tance running by doing such a test after having performed some supra vV˙ O2 max training. The adequacy of the energetic model to predict the performance. We are aware that we cannot explain the performance based on only an energetic model that is supported by the theory that maximal exercise performance is determined by the rate of either oxygen use or ATP production in the exercising muscles. There are now alternative models using the concepts of a central neural governor that constrains the cardiac output by regulating the mass of skeletal muscle that can be activated during maximal exercise in both the acute and the chronic hypoxia [30]. Fatigue as a sensation may occur as an activity process in the brain, but this would involves many areas of the brain and has not yet been determined [30]. However, these two approaches to the energetics and neural conceptions of exercise fatigue are not incompatible because the latter considers that there is a regulation by the brain of the mass of skeletal muscle that can be activated during maximal exercise, and this has direct consequences on E˙ r max. This study shows that the energetics model proposed by di Prampero et al. [5] applied with individual data collected outside and on the track and not on the treadmill and/or a cycle ergometer with standard values for the anaerobic capacity fits with the metabolic power required over middlle-distance running in junior elite male and females middle-distance runners. The difference in E˙ r max aero then explains the difference in performance over 800 m and 1,500 m between males and females that have no significantly different value of E˙ r max anaero. However, E˙ r max anaero allowed us to improve the prediction of the performance over 1,500 m with E˙ r max aero. For the whole group (including both genders), the inclusion of the net energy cost of running improves the prediction of the performance over 800 m, which is possible to the nearest 1.4 s, which is a satisfactory level of accuracy from a physiological point of view (1.5%). The present study showed that E˙ r max aero and E˙ r max anaero provide additional information about the potential for performance and could help coaches in the orientation of training towards aerobic or anaerobic interval-training [25]. Conclusion. The aim of this study was to analyze the variance in performance by examining the partitioning of metabolic power into aerobic and anaerobic components in elite young middle-distance runners according to their gender. In elite junior athletes, the energetic model with individual data measured in an all-out 600 m performance on a track allows the explanation of most of the variance in middle-distance performances between genders. The dis134

tinction of aerobic from anaerobic power allowed an improved prediction of the middle-distance performance, but for females and over 1,500 m only. E˙ r max aero explained most of the variance in the performance (the personal best performed 8 weeks later) between genders: 65% and 79% over 800 m (T800) and 1,500 m (T1,500). For females, E˙ r max aero explained most of the variance of T1,500 (r20.66), and E˙ r max anaero improved this prediction (r20.84). No energetic factor predicted the performance in males. In elite junior athletes, the energetic model with individual data measured over an all-out 600 m on-track performance, provides an explanation for most of the variance in middle-distance performance between genders. The distinction between aerobic and anaerobic power allowed improvement in the prediction of the middledistance performance. Even if the 600 m run was comparable in terms of relative speed to V˙O2 max, it was probably too short for males to estimate their anaerobic work capacity. All measurements were carried out on the field, which is an innovation when compared to previous studies, which have examined predictor variables in the laboratory. The topic is important to an understanding of how human athletes produce power in middle-distance events and if differences exist between men and women. Further studies are needed to explore the limiting factors of each component of the energetic model in the real conditions of track running. This study was supported by grants from the Fondation d’Entreprise Gaz de France and from the Genopole® Evry.

REFERENCES 1. Spencer MR, Gastin PB and Payne WR: Energy system contribution during 400 to 1500 meters running. New Studies Athl 11: 59–65, 1996 2. Spencer MR and Gastin PB: Energy system contribution during 200- to 1500-m running in highly trained athletes. Med Sci Sports Exerc 33: 157–162, 2001 3. Weyand PG, Cureton KJ, Conley DS, Sloniger MA, and Liu YL: Peak oxygen deficit predicts sprint and middledistance track performance. Med Sci Sports Exerc 26: 1174–1180, 1994 4. Wilkie DR: Equations describing power output by humans as a function of duration of exercise. In: Exercise Bioenergetics and Gas Exchange, ed. Cerretelli P and Whipp BJ, Elsevier Publ Co, Amsterdam, pp 75–80, 1980 5. di Prampero PE, Capelli C, Pagliaro P, Antonutto G, Girardis M, Zamparo P, and Soule RG: Energetics of best performances in middle-distance running. J Appl Physiol 74: 2318–2324, 1993 6. Schneider DA, Lacroix KA, Atkinson GR, Troped PJ, and Pollack J: Ventilatory threshold and maximal oxy-

Japanese Journal of Physiology Vol. 54, No. 2, 2004

Energetics in Middle-Distance Running

7.

8.

9.

10.

11.

12.

13.

14.

15.

16.

17.

gen uptake during cycling and running in triathletes. Med Sci Sports Exerc 22: 257–264, 1990 Billat VL, Beillot J, Jan J, Rochcongar P, and Carre F: Gender effect on the relationship of time limit at 100% V˙ O2 max with other bioenergetic characteristics. Med Sci Sports Exerc 28: 1049–1055, 1996 Billat VL, Slawinski J, Danel M, and Koralsztein JP: Effect of free versus constant pace on performance and oxygen kinetics in running. Med Sci Sports Exerc 33: 2082–2088, 2001 Billat VL, Blondel N, and Berthoin S: Determination of the velocity associated with the longest time to exhaustion at maximal oxygen uptake. Eur J Appl Physiol Occup Physiol 80: 159–161, 1999 Billat VL, Morton RH, Blondel N, Berthoin S, Bocquet V, Koralsztein JP, and Barstow TJ: Oxygen kinetics and modelling of time to exhaustion whilst running at various velocities at maximal oxygen uptake. Eur J Appl Physiol 82: 78–87, 2000 Cottin F, Papelier Y, Durbin F, Koralsztein JP, and Billat VL: Effect of fatigue on spontaneous velocity variations in human middle-distance running: use of short-term Fourier transformation. Eur J Appl Physiol 87: 17–27, 2002 Einsenmann JC, Brisko N, Shadrik D, and Welsh S: Comparative analysis of the Cosmed Quark b2 and K4b2 gas analysis systems during submaximal exercise. J Sports Med Phys Fitness 43: 150–155, 2003 McLaughlin JE, King GA, Howley ET, Bassett DR Jr, and Ainsworth BE. Validation of the COSMED K4 b2 portable metabolic system. Int J Sports Med 22: 280– 284, 2001 Joyner MJ: Physiological limiting factors and distance running: influence of gender and age on record performances. Exerc Sport Sci Rev 21: 103–133, 1993 Weber CL and Schneider DA: Maximal accumulated oxygen deficit expressed relative to the active muscle mass for cycling in untrained male and female subjects. Eur J Appl Physiol 82: 255–261, 2000 Weber CL and Schneider DA: Increases in maximal accumulated oxygen deficit after high-intensity interval training are not gender dependent. J Appl Physiol 92: 1795–1801, 2002 Naughton GA, Carlson JS, Buttifant DC, Selig SE, Meldrum K, McKenna MJ, and Snow RJ: Accumulated oxygen deficit measurements during and after high-intensity exercise in trained male and female adolescents. Eur J Appl Physiol Occup Physiol 76: 525–531, 1997

18. Aunola S and Rusko H: Reproducibility of aerobic and anaerobic thresholds in 20–50 year old men. Eur J Appl Physiol Occup Physiol 53: 260–266, 1984 19. Medbo JI and Tabata I: Relative importance of aerobic and anaerobic energy release during short-lasting exhausting bicycle exercise. J Appl Physiol 67: 1881– 1886, 1989 20. Mac Rae HSH, Noakes TD, and Dennis SC: Role of decrease carbohydrate oxidation on slower uses in ventilation with increasing exercise intensity after training. Eur J Appl Physiol 71: 523–529, 1995 21. Medbo JI, Mohn AC, Tabata I, Bahr R, Vaage O, and Sejersted OM: Anaerobic capacity determined by maximal accumulated O2 deficit. J Appl Physiol 64: 50–60, 1988 22. Medbo JI and Burgers S: Effect of training on the anaerobic capacity: Med Sci Sports Exerc 22: 501– 507, 1990 23. Weber CL and Schneider DA: Reliability of MAOD measured at 110% and 120% of peak oxygen uptake for cycling. Med Sci Sports Exerc 33: 1056–1059, 2001 24. Weyand PG, Cureton KJ, Conley DS, and Higbie EJ: Peak oxygen deficit during one- and two-legged cycling in men and women. Med Sci Sports Exerc 25: 584–591, 1993 25. Billat VL: Interval training for performance: a scientific and empirical practice. Special recommendations for middle-and long-distance running. Part II: anaerobic interval training. Sports Med 31: 75–90, 2001 26. Durnin JV and Womersley J: Body fat assessed from total body density and its estimation from skinfold thickness: measurements on 481 men and women aged from 16 to 72 years. Br J Nutr 32: 77–97, 1974 27. Heugas AM, Brisswalter J, and Vallier JM: Effect of a three month training period on the maximal oxygen deficiency in high level performance sprinters Can J Appl Physiol 22: 171–181, 1997 28. Hagberg JM, Hickson RC, Ehsani AA, and Holloszy JO: Faster adjustment to and recovery from submaximal exercise in the trained state. J Appl Physiol 48: 218–224, 1980 29. Olesen HL, Raabo E, Bangsbo J, and Secher NH. Maximal oxygen deficit of sprint and middle distance runners. Eur J Appl Physiol Occup Physiol 69: 140– 146, 1994. 30. Noakes T, Peltonen JE, and Rusko HK: Evidence that a central governor regulates exercise performance during acute hypoxia and hyperoxia. J Exp Biol 204: 3225–3234, 2001

Japanese Journal of Physiology Vol. 54, No. 2, 2004

135