Wung W. E., Howell S. B.: Simultaneous liquid chromatography of. 5-fluorouracil, uridine, hypoxanthine, xynthine, uric acid, allopurinol and oxipurinol in plasma.
Maximal-Intensity Intermittent Exercise: Effect of Recovery Duration 1
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P. D. Balsom , J. Y. Seger', B. Sjödin , B. Ekblom' 1 2
Karolinska Institute, Dept. of Physiology III, Stocldiolm, Sweden National Defence Research Establishment, Stocldiolm, Sweden
Introduction Abstract P. D. Balsom, J. Y. Seger, B. Sjödin and B. Ekblom, Maximal-Intensity Intermittent Exercise: Effect of Recovery Duration. Int J Sports Med, Vol 13, No 7, pp 528 -533, 1992. Accepted after revision: June 21, 1992 Seven male subjects performed 15x40m sprints, on three occasions, with rest periods of either 120 s ( R 1 2 0 ) , 60 s (RÖO) or 30 s (R30) between each sprint. Sprint times were recorded with four photo cells placed at 0, 15, 30 and 40 m. The performance data indicated that whereas running speed over the last 10 m of each sprint decreased in all three protocols (after 11 sprints in R120, 7 sprints in Roo and 3 sprints in R30), performance during the initial acceleration period from 0-15m was only affected with the shortest rest periods increasing from (meantSEM) 2.58±.03 (sprint 1) to 2.78±.04s (sprint 15) (p pre.
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Fig. 5 Mean heart råtes (means ± SEM, n = 7) measured during the first 30 s of recovery periods between sprints in R120 ( • ) , Reo
(V) and R30 (T).
uric acid concentrations were not significantly different for the three tests. Post-exercise plasma uric acid concentrations were higher than resting values in all three protocols (p ^60 or R30 Disucssion
a: 3
-
5
a: 5 - 7
icant increase between VC>2 and VC>2 but there was no further increase along sprints (p>.05). VC>2 corresponded to 52, 57 and 66% of maximum oxygen uptake, in R120, Réu and R30, respectively. a:
W
b 2
(R
m
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andRJ
The mean oxygen uptake measured at the end of the rest periods in R120 was 0.88±.051 -mur , the corresponding value in RÖO was 1.92 ±.11- min . 1
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Heart rate (Fig. 5) There was no significant difference in heart rate measured after sprint 1 for the 3 tests. In R120 heart rate did not change significantly along sprints, but in R60 and R30 it increased (p there was no significant decrease in performance although blood lactate concentration had increased to 10.0+1.1 mmol-r , a value commonly associated with fatigue during continuous exercise. Thus, while blood lactate measurements can be used to confirm that the anaerobic glycolytic pathway has been stimulated during exercise, systemic lactate concentration, per se, is not a good predictor of performance during maximal-intensity intermittent exercise. Furthermore, lactate production in the muscle cannot be quantified by blood lactate concentration due to different råtes of efflux from muscle (cf. 19). 1
Between repeated bouts of maximal-intensity exercies, in vivo, the energy needed to fuel recovery processes in the muscle appears to be supplied exciusively via aerobic glycolysis (5,6). In the current study oxygen uptake was measured during the rest period between sprints to quantify oxygen utilization for recovery processes. A major part of the immediate post-exercise oxygen consumption has been associated with the resynthesis of PCr (16). Although the post-exercise rate of PCr resynthesis may be influenced by such variables as blood flow and intramuscular pH, it has been estimated that the majority of PCr is resynthesized within 2 min (6). This is well in keeping with our observation that oxygen uptake measured during the last 20 s of the 2 min rest periods in R120 had decreased from 2.5 1 • min immediately after each sprint to near pre-test values. In R120, Rfio and R30 oxygen uptake measured immediately after each sprint increased to 52, 57 and 66 % of maximum oxygen uptake, respectively. Based on previous findings which indicate that resynthesis of high energy phosphates is dependent on oxygen supply to muscle (11), it is not clear why a higher fraction of aerobic capacity is not utilized during the rest periods. -1
Heart rate was measured during rest periods simultaneously with the collection of expired air. The mean
Maximal-Intensity
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Exercise: Ejfect of Recoveiy
Duration
values illustrated in Fig. 5 are higher than would be expected based on the corresponding oxygen uptakes. Thus, with this type of exercise it appears that heart rate cannot be used to predict oxygen uptake. Such measurements, which are commonly used in multiple sprints sports, will inevitable overestimate aerobic energy demands (13). In conclusion, the results of this study have confirmed the importance of recovery duration for sustaining performance during repeated sprints. It appears that with this type of exercise the capacity to initially accelerate from a standing start is restored rapidly during intervening recovery periods. However, decreases in running speed towards the end of each sprint indicate that this component of performance is more affected by the metabolic consequences of preceding exercise bouts. These changes in performance could not be explained by the physiological and biochemical measurements made in the current study.
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Acknowledgements The authors wish to thank Elisabeth Malm, Ailo Mikiver and Maarja Mikiver for their excellent technical assistance. References 1
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Balsom P. D., Seger J. Y., Sjödin B., Ekblom B.: Physiological responses to maximal-intensity intermittent exercise. Eur J Appl Physiol 65: 144 149, 1992. Bessman S. R: The creatine-creatine phosphate energy shuttle. Ann RevBiochem 54: 831-862, 1985. Boobis L. H.: Metabolic aspects of fatigue during sprinting. In: Macleod D., Maughan R. X, Nimmo M., Reilly T., Williams C. (eds). Exercise: Benefits, Limitations and Adaptions. E & FN Spon, London, pp 116-140, 1987. Christensen E. H., Hedman R., Saltin B.: Intermittent and continuous running. Acta Physiol Scand 50: 269-286, 1960. Colliander E. B., Dudley G. A., Tesch P. A.: Skeletal muscle fibre type composition and performance during repeated bouts of maximal, concentric contractions. Eur J Appl Physiol 58: 81-86, 1988. Harris R. C, Edwards R. H. T., Hultman E., Nordesjö L.-O., Nylind B., Sahlin K.: The time course of phosphorylcreatine resynthesis during recovery of the quadriceps muscle in man. Pfliigers Arch 367: 137-147, 1976. Hellsten Westing Y , Ekblom B., Sjödin B.: The metabolic relationship between hypoxanthine and uric acid in man following maximal short distance running. Acta Physiol Scand 137: 341-345, 1989. Hellsten-Westing Y , Sellevi A., Sjödin B.: Plasma accumulation of hypoxanthine, uric acid and creatine kinase following exhausting runs of different durations in man. Eur J Appl Physiol 62: 380-384, 1991. Hirvonen I , Rehunen S., Rusko H., Härkönen M.: Breakdown of high-energy phosphate compounds and lactate accumulation during short supramaximal exercise. Eur J Appl Physiol 56: 253-259, 1987. Holmyard D. X, Cheetham M. E., Lakomy H. K. A., Williams C : Effect of recovery duration on performance during multiple treadmill sprints. In: Reilly T., Lees A., Davids K., Murphy W. X (eds). Science and Football. E & FN Spon, London, pp 134-142, 1988. Idström X R, Subramanian V H , Chance B., Schersten X, BylundFellenius A.-C: Oxygen dependence of energy metabolism in contracting and recovering rat skeletal muscle. Am J Physiol 248: H40 -H48, 1985. Karlsson X, Bonde-Petersen E, Henriksson X, Knuttgen G.: Effects of previous exercise with arms or legs on metabolism and performance in exhaustive exercise. JAppl Physiol 38: 763-767, 1975. Karpman V L.: Cardiovascular system and physical exercise. Florida, CRC Press Inc., 1987, p 166.
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P. D. Balsom Karolinska Institute Dept. of Physiology III Box 5626 Stockholm 11486 Sweden
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