Effect of Pacing on Oxygen Uptake and Peak Lactate for a Mile Run

Transcription

1 Europ. J. appl. Physiol. 32, (1974) 9 by Springer-Verlag 1974 Effect of Pacing on Oxygen Uptake and Peak Lactate for a Mile Run Luc A. L6ger and Ronald J. Ferguson* D6partment d'education Physique, Universit6 de Montr6al, Montr6aI, Qu6bec Received August 20/November 5, 1973 Abstract. The purpose of this study was to determine if pace changes similar to those experienced in competition could affect the relative contribution of aerobic and anaerobic processes to overall energy utilization during running. In particular, does a fast start in the mile race increase the energy supplied aerobically during the first three-quarters of a mile such that the lactate formation is reduced prior to the usual rapid last quarter? Eight subjects (middle and long distance runners) ran three-quarters of a mile on a treadmill according to a fast-medium-very slow (F-M-S) and a slow-medium-slow pace. The two paces were performed in a random order and the total running times were equal. No significant differences were found between the two paces for oxygen uptake during the runs, for the 15-rain recovery oxygen and for the post-exercise peak lactate values. Although several world class milers have employed a fast-medium-slow-fast pace, the present data concerning the relative contribution of different energy sources do not explain why this might be the best pacing technique. Key words: Oxygen Uptake -- Peak Lactate -- Mile Pacing -- Recovery Oxygen -- Oxygen Debt. For athletic events involving prolonged work and a marked oxygen deficit during the 1st min, Astrand and Rodahl (4:286) have suggested that it might be advantageous to increase the I?o 2 rapidly. Although this would exhaust ereatine phosphate stores, the rapid attainment of 1)o2 max would tend to diminish the rate of lactate formation during the event. It is interesting to note that numerous mile races including those of Ryun (3 rain, 5t.3 see), Jazy (3 rain, 53.6 see) and Keino (3 min, 54.2 see), were run according to a fast-medium-slow-fast place 1. Runners may empirically choose a pace which is physiologically the most favorable although tactical and even psychological reasons might altogether explain pace alteration. The purpose of this study was to determine if pace changes similar to those experienced in competition could affect the relative contribution * The aid of Mr. Paul Martin was greatly appreciated. 1 Based on quarter-mile split times. 18 Europ. J. appl. Physiol., u 32

2 252 L. A. L6ger and 1%. J. Ferguson Table 1. Subject description Subjects Age Weight Height Vo~ max Performance times (yr) (kg) (m) (ml/kg-min) (hr :rain :sec) M S 29 7L :29.0 b t6:01.9o R P :01.4~ 15:31.7~ F V :04.6 e t5:10.8 o W S :36g 16:13.0o I) M :49.5 h i :55.4 i N C t :40.0 e 33:00.0 a R F " 17:05 ~ 34:58:0 a L L :03 i 17:50.4 ~ t S~ n : 47.0 a 2:35:38 f 2:40:24~ 4 : 25.0 e 2:46:52f 1:28:05J 1:37:00J Not included in the mean, obtained 2 months before the tests. b3000m; c5000m; a10000m; et500m; fmarathon; g2mi; i 800 m; J 24 km. 400 m; of aerobic and anaerobic processes to overall energy utilization during running. In particular, does a fast start in the mile race increase the energy supplied aerobically during the race? Materials and Methods Eigth middle and long distance runners (Table l), whose performances for the mile ranged from 4 rain 20 sec to 5 min, participated in this study. Except for the ~z max determination, the majority of the subjects had no treadmill experience previous to the execution of the experimental conditions. Two running paces (Fig. 1) for the first three-quarters of a mile, a fast-mediumvery slow pace (F-M-S) and a slow-medium-slow pace (S-M-S) were run at random on a motor-driven treadmill. The laboratory temperature, relative humidity and barometric pressure were approximately 25 ~ 44 % and 760 mmhg respectively. The paces were designed to respect the following conditions: t. The total time for the three-quarters of a mile was equal, 2. the difference between a fast and a slow first quarter was based on the normal pace variations occurring in competition, and 3. the intensity of the test was supramaximal in order to reach the Voz max within a minute. To respect the test conditions the subjects ran at their competition speeds. Split times are expressed in percent of the total performance time. Therefore for the first three-quarters of a mile, the average split times for F-M-S and S-M-S were 24.7, 25A, 26.2 and 25.4, 25A, 25.5% respectively. A paired "t" test showed significant differences (P < 0.001) between the two paces and for the quarter-mile pace variations within each race. According to their training habits, the subjects were allowed from 5 to 20 min to warm-up. The warm-up for a given subject was the same for the two paces. The start was similar to the one employed in competition. At the command "Go" the revolution counter and the stop-watches were started. The pre-seleeted speed was

3 I?o~, LA and Mile Pacing 253 1&0 o_ E,', 12.5 Lq Ld O- O I I I DISTANCE (mile) Fig. 1. Experimental paces: Solid line fast-medium-very slow (F-M-S) and broken line slow-medium-slow (S-M-S) reached with a minimal delay such that it increased the time of the first quarter by only 0.06 see compared to a theoretical constant speed. The treadmill speed was calibrated before and after the investigation with subjects weighing 62 and 87 kg. Speed changes at each quarter-mile did not require more than 1 sec. Distance run was determined by a counter of treadmill belt revolutions. Quarter-mile split times were determined by means of an electronic marker. G~ was measured for each quarter of a mile and during the first 15 min of recovery with an open-circuit method using a dry gas-meter (Parkinson-Cowan CD-4) with a potentiometer to record directly the expired volume. A continuous sample of expired gas was withdrawn from an 8-Iiter mixing box and was analyzed with precalibrated physiem analyzers. The details of the method and the multistage test of [?o2 max have been described elsewhere ill ]. The peak lactate was determined from the analysis of three blood samples of 0,05 ml taken from a pre-warmed (5 min at 45 ~ finger from the 5th to the t0th rain of recovery. The collected sample was at once mixed with triehloroacetic acid, the whole operation taking 10 to 15 sec. This mixture was frozen for a period not exceeding I month. After defrosting, the samples were centrifuged and analyzed all at once with the standards ad modum Barker and Snmmerson [5] as modified by Strom [28]. Heart rate was calculated from a bipolar EKG (C5-C5R) during the last t0 sec of each quarter-mile. Comparisons between the two paces were analyzed with a paired "t" test. Results No significant difference was found between the two paces for l?o~ and heart rate during the first quarter of mile, for total l?o 2 during the run, for recovery Vo2 and peak lactate (Table 2). Vo2 during the second quarter of mile was significantly higher for S-~-S compared to F-IV[-S (P< 0.05). Oxygen uptake for the three quarter-miles, expressed as a percent of I?o 2 max, was 58, 84, 88% and 56, 86, 90% for F-M-S and S-M-S respectively. These percentages were calculated for five subjects z. A significant difference between paces appeared for the third quarter of the mile only (Table 2). 18" 2 Three of the 8 subjects were not available to perform the 17o2 max test.

4 Table 2. ~2, heart rate, peak lactate and split times for the I~'-M-S and S-M-S paces b Po2 (l/rain) S-M-S l?o~ ( % max) ~ Heart rate LA peak (mg- %) (beats/min) a F-M-S S-M-S F-M-S S-M-S F-M-S S-M-S F-M-S Split times (sec) F-M-S S-1Vi-S 0.0O to 0.25 mile t ~ 70.8 (0.11) (0.08) (1.52) (1.12) (4) (4) (I.05) (1.05) 0.25 to 0.50 mile 4.t6 e , (0.tl) (0.11) (3.05) (3.43) (4) (4) (1.t0) (1.03) 0.50 to 0.75 mile t ~ : 70.9 (0A0) (0.t0) (3.17) (2.92) (4) (3) (1.t9) (1.05) 0.00 to 0.75 mile t3.28~ (0.35) (0.28) (3.30) (3.14) Recovery (15 min) -- tt.75~ 1t t (0.53) (0.29) (7) (12) Values are totals in liters and not rates/rain, b Values are means and standard errors. " n = 5. a n = 7, ~ P < ~ P < cm 8

5 ~2, LA and Nile Pacing 255 Discussion In general, the results of this study showed that variations of speed similar to those experienced in competition do not effect the distribution of aerobic and anaerobic energy sources. The only significant difference observed, ~ for the second quarter of mile, may be attributed to chance since the equivalent measure expressed as a percentage of I?o2 max was not significant. For this reason and since total ~2 during work was not different between paces, this difference was neglected in the following discussion. A fast start does not seem to be able to increase I)o 2 at work and to decrease lactate formatiort and I?o~ during recovery. In fact, the opposite may be the case. Analysis of individual results showed that only three subjects out of the eight had lower lactates for whichever experimental pace had the higher l)o 2 during the run. This pattern is in agreement with other studies [1, 7, ~15, 23, 24, 25, 30] and would conform to the law of mass action. Thus, increasing l)o~ faster does not seem to avoid lactate formation, neither does it conserve creatine phosphate (CP) since there is probably a complete depletion of CP right at the beginning of submaximal and maximal work [16]. Adams and Bernauer [1] and Robinson et al. [24] obtained significant differences in the total net energy cost (net 1)o2 at work + net 1)o2 during recovery) of different paces. Based on O~ debt measurements made after subjects ran a 100 yards dash while holding their breath, Sargent [26] recommended a constant speed. A close analysis of the data of Adams and Bernaner [t] and Robinson et al. [24] shows that differences in total energy cost with various paces were only due to differences in the oxygen "debt". The oxygen "debt", or the recovery oxygen, as suggested by Stainsby and Barclay [27], is not a direct measure, nor an accurate estimation of the anaerobic energy (i.e. CP stores, and anaerobic glycolysis) expended during work [4, 6, 8, 9, t3, t7--20]. It may be argued that some of the conditions of the experimental design were not respected and could therefore explain why the data failed to support the hypothesis. For example, the work was supposed to be supramaximm whereas the highest percentage of l)o~ max attained was 90%. This investigation was also based on the assumption that ~2 max could be reached within a minute at a supramaximal work load (4:286, 29) although other studies [10, t2, 21, 22, 27] indicate that this may not be true. This latter option is supported by the present data and by the subjective report of exhaustion experienced by the subjects running at competitive speeds. The percentage of 1)o2 max may also not reflect the true intensity of the work. l)o 2 max was determined on a 5.25% grade whereas the pacing runs were conducted at 0 % grade. The greater muscle mass involved in grade running may elicit a higher l?o~ max than

6 256 L. A. L6ger and g. J. Ferguson a 0% test [2, 3, i4, 29]. This could partly explain the low percentage Vo2 max attained in this study. Astrand et al. (4:286) have shown that a warm-up can increase l?o 2 more rapidly during a subsequent workload. This could lessen the effect of a fast start and partly explain the absence of a significant difference between F-M-S and S-M-S. Similarly, the small difference in speed between the two conditions might also explain the lack of significant difference, particularly for the first quarter of mile. However, athletes warm-up prior to races and the experimental variations in pace correspor~ded to the maximum range encountered in competition. In conclusion, this study showed that pace variations, as occurring in competition, are not likely to produce any energy source redistribution. The possibility of an energy redistribution is also questioned. References 1. Adams, W. C., ]3ernauer, E. M.: The effect of selected pace variations on the oxygen requirement of running a 4~:37 mile. Res. Quart. 89, (t968) 2. Astrand, 1). 0., Saltin, ]3.: Maximal oxygen uptake and heart rate in various types of muscular activity. J. appl. Physiol. 16, (1961) 3. Astrand, 1). 0.: Measurement of maximal aerobic capacity. Canad. reed. Ass. J. 96, ) 4. Asbrand, 1 ). O., Rodahl, K. : Textbook of work physiology. New York: McGraw- Hill i ]3arker, S. ]3., Summerson, W. H. : The colorimetric determination of lactic acid in biological material. J. biol. Chem. 148, (1941) 6. :Brooks, G. A., I-Iittelman, K. J., ~aulkner, J. A., ]3eyer, R. E.: Temperature, squeletal muscle mitochondrial functions, and oxygen debt. Amer. J. Physiol. 220, (i971) 7. Carlson, L., 1)ernow, ]3. : Studies on the peripheral circulation and metabolism in man. Acta physiol, sound. 52, (1961) 8. Christensen, H. E., Hogberg, 1). : The efficiency of anaerobic work. Arbeitsphysiologie 14, (1950) 9. Christensen, H. E., Hogberg, 1). : Steady-state 02-debt at severe work. Arbeitsphysiologic 14, : (1950) 10. Costill, D. L. : Metabolic responses during distance running. J. appl. 1)hysiol. 28, 25i--255 (i970) 11.1%rguson, 1~., Montpetit, R., Dubuc, g., Gingras, Y.: L'entrainement du syst~me de transport d'oxyg~ne par la course continue et par intervalles. Kinanthropologie 2, ~71--t79 (4970) 12. Glassford, R. G., ]3aycroft, G. H. Y., Sedgwiek, A. W., Macnab, R. ]3. J. : Comparison of maximal oxygen uptake values determined by predicted and actual methods. J. appl. 1)hysiol. 20, (1965) i3. Harris, 1 ).: Lactic acid and the phlogiston debt. Cardiovasc. Res. 3, (4969) t4. Hermansen, L., Saltin, ]3.: Oxygen uptake during maximal treadmill and bicycle exercise. J. appi. 1)hysiol. 26, (1969) 15. Jorfeldt, L. : Metabolism of L( + )-Lactate in human skeletal muscle during exercise. Acta physiol, scand. 78, Suppl. 338, (1970)

7 l?o,, LA and Mile Pacing Karlson, J., Saltin, B.: Lactate, ATP and CP in working muscle during exhaustive exercise in man. J. appl. Physiol. 29, (1970) t7. Keul, J., Nett, T.: "Oxygen debt" and anaerobic energy formation. Track Technique 43, (1971) i8. Knuttgen, H. G.: Oxygen debt, lactate, pyruvate, and excess lactate after muscular work. J. appl. Physiol. 17, (1962) 19. Knuttgen, H. G.: Oxygen debt after submaximal physical exercise. J. appl. Physiol. 98, (t970) 20. Margaria, R., Cerretelli, P., di Prampero, P. E., Massari, C., Torelli, G. : Kinetics and mechanism of oxygen debt contraction in man. J. appl. Physiol. 18, 37t (1963) 21. Nagle, F., Balke, B., Baptista, G., Alleyia, J., Howley, E. : Compatibility of progressive treadmill, bicycle and step tests based on oxygen uptake responses. Med. Sci. Sports 3, (1971) 22. Nagle, F., I~obinhold, D., Howley, E., Daniels, J., Baptista, G., Stodefalke, K. : Lactic acid accumulation during running at submaximal demends. Med. Sci. Sports 9, t (1970) 23. Pernow, B., Wahren, J., Zetterquist, S. : Studies ob the peripheral circulation and metabolism in man. IV. Oxygen utilization and lactate formation in the legs of healthy young men during strenuous exercise. Acta physiol, seand. 64, (1965) 24. Robinson, S., Robinson, D. L., Montjoy, R. J., Bullard, R. W.: Influence of fatigue on the efficiency of men during exhausting runs. J. appl. Physiol. 19, i (1958) 25. Rowell, L. B., Kraning, K. K., Evans, T. 0., Kennedy, J. W., Blackmon, J. R., Kusumi, F. : Splanchic removal of lactate and pyruvate during prolonged exercise in man. J. appl. Physiol. 21, t (1966) 26. Sargent, R. M. : The relation between oxygen requirement speed in running. Proc. roy. Soc. B 100, i0--22 (1926) 27. Stainsby, W. N., Barclay, J. K. : Exercise metabolism: O 2 deficit, steady level 02 uptake and O~ uptake for recovery. Med. Sci. Sports l, t (1970) 28. Strom, G. : The influence of anoxia on lactate utilization in man after prolonged muscular work. Aeta physiol, seand. 17, (1949) 29. Taylor, It. L., Buskirk, E., ttenschel, A.: Maximal oxygen intake as an objective measure of cardio-respiratory performance. J. appl. Physiol. 8, (1955) 30. Wahren, J. : Quantitative aspects of blood flow and oxygen uptake in the human forearm during rhythmic exercise. Acta physiol, seand. 67, Suppl. 269 (1966) Dr. Lue A. L6ger D6partement d'education Physique Universit6 de Montr6al Case Postale 6178 Montr6al 101, Quebec, Canada