Journal of Comparative Physiology B

, Volume 157, Issue 6, pp 791–799 | Cite as

Dynamics of cardiorespiratory function in Standardbred horses during different intensities of constant-load exercise

  • D. L. Evans
  • R. J. Rose
Article

Summary

Six Standardbred horses were used to evaluate the time course of pulmonary gas exchange, ventilation, heart rate (HR) and acid base balance during different intensities of constant-load treadmill exercise. Horses were exercised at approximately 50%, 75% and 100% maximum oxygen uptake (\(\dot V_{{\text{O}}_2 } \) max) for 5 min and measurements taken every 30 s throughout exercise. At all work rates, the minute ventilation, respiratory frequency and tidal volume reached steady state values by 60 s of exercise. At 100%\(\dot V_{{\text{O}}_2 } \) max, the oxygen consumption (\(\dot V_{{\text{O}}_2 } \)) increased to mean values of approximately 130 ml/kg·min, which represents a 40-fold increase above resting\(\dot V_{{\text{O}}_2 } \). At the low and moderate work rates,\(\dot V_{{\text{O}}_2 } \) showed no significant change from 30 s to 300 s of exercise. At the high work rate, the mean\(\dot V_{{\text{O}}_2 } \) at 30 s was 80% of the value at 300 s. The HR showed no significant change over time at the moderate work rate but differing responses at the low and high work rates. At the low work rate, the mean HR decreased from 188 beats/min at 30 s to 172 beats/min at 300 s exercise, whereas at the high work rate the mean HR increased from 204 beats/min at 30 s to 221 beats/min at 300 s exercise. No changes in acid base status occurred during exercise at the low work rate. At the moderate work rate, a mild metabolic acidosis occurred which was nonprogressive with time, whereas the high work rate resulted in a progressive metabolic acidosis with a base deficit of 16 mmol/l by 300 s exercise. It is concluded that the kinetics of gas exchange during exercise are more rapid in the horse than in man, despite the relatively greater change in\(\dot V_{{\text{O}}_2 } \) in the horse when going from rest to high intensity exercise.

Keywords

Metabolic Acidosis Work Rate Minute Ventilation Treadmill Exercise Acid Base 

Symbols and abbreviations

E

minute ventilation

VT

tidal volume

\(\dot V_{{\text{O}}_2 } \)

oxygen uptake

\(\dot V_{{\text{CO}}_2 } \)

carbon dioxide output

\(\dot V_{{\text{O}}_{\text{2}} } /{\text{HR}}\)

oxygen pulse

\(\dot V_{\text{E}} /\dot V_{{\text{O}}_{\text{2}} } \)

ventilatory equivalent for oxygen

\(\dot V_{\text{E}} /\dot V_{{\text{CO}}_{\text{2}} } \)

ventilatory equivalent for carbon dioxide

R

respiratory exchange ratio

HR

heart rate

SBC

standard bicarbonate

STPD

standard temperature and pressure dry

BTPS

body temperature and pressure saturated

\(C{\text{a}}_{{\text{O}}_{\text{2}} } \)

arterial oxygen content

\(C(a - \bar v)_{{\text{O}}_{\text{2}} } \)

arteriovenous oxygen content difference

Rf

respiratory frequency

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Åstrand P-O, Rodahl K (1977) Textbook of work physiology, 2nd edn. McGraw-Hill, New YorkGoogle Scholar
  2. Attenburrow DP (1982) Time relationship between the respiratory cycle and limb cycle in the horse. Equine Vet J 14:69–72Google Scholar
  3. Barr SA, Glasser RM, Fox RM, Bartels R, Gabel AA (1981) Effects of training on oxygen kinetics of Standardbred horses during exercise. Fed Proc 40:498Google Scholar
  4. Bayly WM (1979) A non-invasive technique for the measurement of oxygen consumption in horses exercising on a treadmill. MS thesis, Ohio State UniversityGoogle Scholar
  5. Bennett FM, Reischl P, Grodins FS, Yamashiro SM, Fordyce WE (1981) Dynamics of ventilatory response to exercise in humans. J Appl Physiol 51:194–203Google Scholar
  6. Bisgard GE, Forster HV, Byrnes B, Stanek K, Klein J, Manohar M (1978) Cerebrospinal fluid acid-base balance during muscular exercise. J Appl Physiol 45:94–101Google Scholar
  7. Bramble DM, Carrier DR (1983) Running and breathing in mammals. Science 219:251–256Google Scholar
  8. Cerretelli P, Sikand R, Farhi LE (1966) Readjustments in cardiac output and gas exchange during onset of exercise and recovery. J Appl Physiol 21:1345–1350Google Scholar
  9. Deegan E, Buntenkotter S (1976) Behaviour of the heart rate of horses with auricular fibrillation during exercise and after treatment. Equine Vet J 8:26–29Google Scholar
  10. Dempsey J, Hanson P, Pegelow D, Claremont A, Rankin J (1982) Limitations to exercise capacity and endurance: pulmonary system. Can J Appl Spt Sci 7:4–13Google Scholar
  11. Dempsey JA, Hanson PG, Henderson KS (1984a) Exercise-induced arterial hypoxaemia in healthy human subjects at sea level. J Physiol 355:161–175Google Scholar
  12. Dempsey JA, Mitchell GS, Smith CA (1984b) Exercise and chemoreception. Am Rev Respir Dis 129:S31-S34Google Scholar
  13. Dempsey JA, Vidruk EH, Mitchell GS (1985) Pulmonary control systems in exercise: update. Fed Proc 44:2260–2270Google Scholar
  14. Dejours P (1975) Principles of comparative respiratory physiology. North Holland Publishing Company, AmsterdamGoogle Scholar
  15. Diamond LB, Casaburi R, Wasserman K, Whipp BJ (1977) Kinetics of gas exchange and ventilation in transitions from rest or prior exercise. J Appl Physiol 43:704–708Google Scholar
  16. Engelhardt W von (1977) Cardiovascular effects of exercise and training in horses. Adv Vet Sci Comp Med 21: 173–205Google Scholar
  17. Evans DL, Rose RJ (1986) Method of investigation of the accuracy of four digitally-displaying heart rate meters suitable for use in the exercising horse. Equine Vet J 18:129–132Google Scholar
  18. Evans DL, Rose RJ (1987) Maximal oxygen consumption in racehorses. In: Robinson NE, Gillespie JR (eds) Equine exercise physiology II. Edwards Brothers, Ann Arbor (in press)Google Scholar
  19. Forster HV, Pan LG, Bisgard GE, Dorsey SM, Britton MS (1984) Temporal pattern of pulmonary gas exchange during exercise in ponies. J Appl Physiol 57:760–767Google Scholar
  20. Hansen JA (1982) Exercise testing. In: Clausen JL (ed) Pulmonary function testing guidelines and controversies. Academic Press, New York, pp 259–279Google Scholar
  21. Hochachka PW (1985) Fuels and pathways as designed systems for support of muscular work. J Exp Biol 115:149–164Google Scholar
  22. Jones NL (1980) Blood gases and acid base physiology. Brian C. Decker, New YorkGoogle Scholar
  23. Jones NL, Campbell EJM (1982) Clinical exercise testing. Saunders, PhiladelphiaGoogle Scholar
  24. Lindholm A, Saltin B (1974) The physiological and biochemical response of Standardbred horses to exercise of varying speed and duration. Acta Vet Scand 15:310–324Google Scholar
  25. Linnarsson D (1974) Dynamics of pulmonary gas exchange and heart rate changes at start and end of exercise. Acta Physiol Scand [Suppl]415:1–68Google Scholar
  26. Littlejohn A, Bowles F, Aschenborn G (1983) Cardiorespiratory adaptations to exercise in riding horses with chronic lung disease. In: Snow DH, Persson SGB, Rose RJ (eds) Equine exercise physiology, Granta, Cambridge, pp 33–45Google Scholar
  27. Marconi C, Pendergast D, Krasney JA, Rennie DW, Cerretelli P (1982) Dynamic and steady state metabolic changes in running dogs. Respir Physiol 50:93–110Google Scholar
  28. Pan LG, Forster HV, Bisgard GE, Dorsey SM, Busch MA (1984) Cardiodynamic variables and ventilation during treadmill exercise in ponies. J Appl Physiol 57:753–759Google Scholar
  29. Persson SGB (1967) On blood volume and working capacity in horses. Acta Vet Scand [Suppl]19:1–189Google Scholar
  30. Persson SGB, Lydin G (1973) Circulatory effects of splenectomy in the horse. III. Effect on pulse-work relationship. Zentralbl Vet Med A 20:521–530Google Scholar
  31. Rose RJ, Evans DL (1986) Metabolic and respiratory responses to prolonged submaximal exercise in the horse. In: Saltin B (ed) Biochemistry of exercise VI. Human Kinetics, Champaign, Illinois, pp 459–466Google Scholar
  32. Thomas DP, Fregin GF (1981) Cardiorespiratory and metabolic responses to treadmill exercise in the horse. J Appl Physiol 50:864–868Google Scholar
  33. Wasserman K (1978) Breathing during exercise. N Engl J Med 298:780–785Google Scholar
  34. Wasserman K, Van Kessel AL, Burton GG (1967) Interaction of physiological mechanisms during exercise. J Appl Physiol 22:71–85Google Scholar
  35. Wasserman K, Whipp BJ (1975) Exercise physiology in health and disease. Am Rev Respir Dis 112:219–249Google Scholar
  36. Wasserman K, Whipp BJ, Koyal SN, Cleary MG (1975) Effect of carotid body resection on ventilation and acid-base control during exercise. J Appl Physiol 39:354–358Google Scholar
  37. Whipp BJ (1971) Rate constant for the kinetics of oxygen uptake during light exercise. J Appl Physiol 30:261–263Google Scholar
  38. Whipp BJ (1981) The control of exercise hyperpnea. In: Hornbein TF (ed) Regulation of breathing, part 2. Marcel Dekker, New York, pp 1069–1139Google Scholar
  39. Whipp BJ, Wasserman K (1972) Oxygen uptake kinetics for various intensities of constant-load work. J Appl Physiol 33:351–356Google Scholar

Copyright information

© Springer-Verlag 1988

Authors and Affiliations

  • D. L. Evans
    • 1
  • R. J. Rose
    • 1
  1. 1.Department of Veterinary Clinical StudiesUniversity of SydneySydneyAustralia

Personalised recommendations