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Dynamic and steady-state metabolic changes in running dogs
Respiration Physiology
|October 1, 1982
Summary
Tracheostomized dogs showed faster oxygen uptake (VO2) on-responses during uphill exercise compared to intact dogs. The energy cost of breathing (VE) significantly impacts overall energy expenditure at higher running speeds.
Area of Science:
- Exercise Physiology
- Animal Physiology
- Cardiorespiratory Function
Background:
- Understanding the physiological responses to exercise is crucial for optimizing performance and health.
- Investigating the impact of airway modification on exercise physiology provides insights into respiratory control and energy metabolism.
Purpose of the Study:
- To compare dynamic and steady-state cardiorespiratory responses to uphill exercise in intact versus tracheostomized dogs.
- To assess the kinetics of oxygen uptake (VO2) and the energy cost of breathing (ventilation, VE) during varying exercise intensities.
Main Methods:
- Measurements of VO2, VE, VCO2, PaO2, and blood lactate (Lab) in 4 intact and tracheostomized dogs during treadmill walking and running at a 10% incline.
- Analysis of non-steady-state (response times) and steady-state parameters at speeds up to 12 km/h.
Main Results:
- Tracheostomized dogs exhibited a significantly faster VO2 on-response (t1/2 = 15.6s) compared to intact dogs (t1/2 = 18.9s).
- Steady-state VO2 and VE plateaued at speeds above 8 km/h, with higher asymptotic values in intact dogs.
- The energetic cost of breathing was estimated at approximately 12 ml O2 per liter of VE.
Conclusions:
- The adjustment of oxidative metabolism at exercise onset is rapid in the whole animal and can be monitored via upper airway gas exchange.
- At higher speeds, the cost of ventilation becomes a substantial component of total energy expenditure, particularly when anaerobic glycolysis is minimized.