Fatigue Responses in Exercise under Control of V·O₂

Abstract

To examine the fatigue response during an exhaustive heavy exercise performed under control of oxygen uptake (SS@V·O₂Δ50) or power output (SS@pΔ50), eleven trained male subjects performed an incremental test to determine the peak of the oxygen uptake value (V·O_2peak) and lactate threshold and two exhaustive steady-state cycling exercises at the intermediate value between the lactate threshold and V·O_2peak (SS@V·O₂Δ50 and SS@pΔ50). The control of V·O₂ induced an oscillation of the power output, which lowered the average power output (276 ± 47 vs. 315 ± 40 W, p = 0.004) and cancelled the slow component of oxygen kinetics. However, all subjects reached maximal cardiac output (CO) and heart rate (HR) values which were sustained almost two times longer in SS@V·O₂Δ50 compared to SS@pΔ50 (979 ± 854 vs. 475 ± 236 s, p = 0.046 for CO and 1050 ± 890 vs. 513 ± 288 s, p = 0.037 for HR). Furthermore, SS@pΔ50 elicited V·O_2peak but not SS@V·O₂Δ50 (4963 ± 434 vs. 4723 ± 460 mL · min^-1, p = 0.026). Finally, the time spent at the maximal CO and HR values is correlated with time to exhaustion at V·O₂Δ50. In conclusion, the cause of fatigue does not seem to have the same origin during exhaustive supra-lactate threshold exercise under control of V·O₂ (V·O₂Δ50) compared to constant power output (pΔ50), while both elicit the maximal HR and CO values.

Key words

V·O₂ kinetics - cardiac output - cycling exercise - heart rate - heavy intensity - stochastic exercise

References

• 1 Aunola S, Rusko H. Reproducibility of aerobic and anaerobic threshold on 20 - 50 year old men.  Eur J Appl Physiol. 1986;  53 260-266
• 2 Barstow T J. Characterization of V·O₂ kinetics during heavy exercise.  Med Sci Sports Exerc. 1994;  26 2099-2106
• 3 Billat V L, Blondel N, Berthoin S. Determination of the velocity associated with the longest time to exhaustion at maximal oxygen uptake.  Eur J Appl Physiol. 1999;  80 159-161
• 4 Billat V L, Koralsztein J P. Significance of the velocity at V·O_2max and time to exhaustion at this velocity.  Sports Med. 1996;  22 90-108
• 5 Billat V L, Morton R H, Blondel N, Berthoin S, Bocquet V, Koralsztein J P, Barstow T J. Oxygen kinetics and modelling of time to exhaustion whilst running at various velocities at maximal oxygen uptake.  Eur J Appl Physiol. 2000;  82 178-187
• 6 Billat V L, Richard R, Binsse V M, Koralsztein J P, Haouzi P. The V·O₂ slow component for a severe exercise depends on type of exercise and its not correlated with time to fatigue.  J Appl Physiol. 1998;  85 2118-2124
• 7 Billat V L, Richard R, Lonsdorfer E, Lonsdorfer J. Stroke volume increases in an all-out severe cycling exercise in moderate trained subjects.  Med Sci Sports Exerc. 2001;  33 S96
• 8 Borrani F, Candau R, Millet G Y, Perrey S, Fuchslocher J, Rouillon J D. Is the V·O₂ slow component dependent on progressive recruitment of fast-twitch fibers in trained runners?.  J Appl Physiol. 2001;  90 2212-2220
• 9 Charloux A, Lonsdorfer-Wolf E, Richard R, Lampert E, Oswald-Manmosser M, Mettauer B, Geny B, Lonsdorfer J. A new impedance cardiograph device for non-invasive evaluation of cardiac output at rest and during exercise: comparison with the “direct” Fick method.  Eur J Appl Physiol. 2000;  82 313-320
• 10 Coyle E F. Cardiovascular drift during prolonged exercise and the effects of dehydration.  Int J Sports Med. 1998;  19 (Suppl 2) S121-S124
• 11 Dampney R A, Coleman M J, Fontes M A, Hirooka Y, Horiuchi J, Li Y W, Polson J W, Potts P D, Tagawa T. Central mechanisms underlying short- and long-term regulation of the cardiovascular system.  Clin Exp Pharmacol Physiol. 2002;  29 261-268
• 12 Delp M D. Control of skeletal muscle perfusion at the onset of dynamic exercise.  Med Sci Sports Exerc. 1999;  31 1011-1018
• 13 Durnin J V, Womersley J. Body fat assessed from total body density and its estimation from skin-fold thickness: measurements on 481 men and women aged from 16 to 72 years.  Br J Nutr. 1974;  32 77-97
• 14 Gaesser G A, Poole D. The slow component of oxygen uptake kinetics in humans.  Exerc Sport Sci Rev. 1996;  24 35-70
• 15 Gonzalez-Alonso J, Mora-Rodriguez R, Coyle E F. Stroke volume during exercise: interaction of environment and hydration.  Am J Physiol. 2000;  278 H321-H330
• 16 Goodman J M, McLaughlin P R, Liu P P. Left ventricular performance during prolonged exercise: absence of systolic dysfunction.  Clin Sci (Lond). 2001;  10 529-537
• 17 Grassi B. Skeletal muscle V·O₂ on-kinetics: set by O₂ delivery or by O₂ utilization? New insights into an old issue.  Med Sci Sports Exerc. 2000;  32 108-116
• 18 Jensen-Urstad M, Bouvier F, Nejat M, Saltin B, Brodin L A. Left ventricular function in endurance runners during exercise.  Acta Physiol Scand. 1998;  164 167-172
• 19 Koppo K, Bouckaert J, Jones A M. Oxygen uptake kinetics during high-intensity arm and leg exercise.  Respir Physiol Neurobiol. 2002;  133 241-250
• 20 Krip B, Gledhill N, Jamnik V, Warburton D. Effect of alterations in blood volume on cardiac function during maximal exercise.  Med Sci Sports Exerc. 1997;  29 1469-1476
• 21 Kuipers H, Verstappen F T, Keizer H A, Geurten P, van Kranenburg G. Variability of aerobic performance in the laboratory and its physiological correlates.  Int J Sports Med. 1985;  6 197-201
• 22 Lepretre P M, Koralsztein J P, Billat V L. Effect of exercise intensity on relationship between V·O_2max and cardiac output.  Med Sci Sports Exerc. 2004;  36 1357-1363
• 23 Maiolo C, Melchiorri G, Lacopino L, Masala S, de Lorenzo A. Physical activity energy expenditure measured using a portable telemetric device in comparison with a mass spectrometer.  Br J Sports Med. 2003;  37 445-446
• 24 Nassis G P, Geladas N D. Cardiac output decline in prolonged dynamic exercise is affected by the exercise mode.  Pflügers Arch. 2002;  445 398-404
• 25 Pyne D B, Boston T, Martin D T, Logan A. Evaluation of the Lactate Pro blood lactate analyser.  Eur J Appl Physiol. 2000;  82 112-116
• 26 Whipp B J, Ozyener F. The kinetics of exertional oxygen uptake: assumptions and inferences.  Sport Med. 1998;  51 139-149
• 27 Xu F, Rhodes E C. Oxygen uptake kinetics during exercise.  Sports Med. 1999;  27 313-327