Dynamic exercise training in foxhounds. I. Oxygen consumption and hemodynamic responses

Area of Science:

• Exercise Physiology
• Canine Sports Medicine
• Cardiovascular Adaptations

Background:

• Understanding exercise adaptations in canines is crucial for performance and health.
• Previous research in humans and rodents shows significant improvements in maximal oxygen consumption (VO2max) with endurance training.

Purpose of the Study:

• To investigate the effects of a structured endurance training program on maximal and submaximal exercise parameters in foxhounds.
• To determine the physiological mechanisms underlying changes in VO2max following training.

Main Methods:

• Ten foxhounds underwent an 8-12 week training program (80% maximal heart rate, 1 hr/day, 5 days/wk).
• Maximal and submaximal exercise tests were conducted on a treadmill before and after training.
• Measurements included oxygen consumption (VO2max), cardiac output, arteriovenous oxygen difference, mean arterial pressure, systemic vascular resistance, and venous lactate concentrations.

Main Results:

• VO2max increased by 28% post-training, mainly due to a 27% rise in maximal cardiac output.
• Maximal arteriovenous oxygen difference showed only a 4% increase, indicating central adaptations were primary.
• Submaximal exercise revealed lower heart rates and higher stroke volumes, with reduced venous lactate concentrations at submaximal levels.

Conclusions:

• Endurance training significantly enhances VO2max in foxhounds, driven predominantly by increased stroke volume.
• These adaptations in canines mirror those observed in humans and rats, emphasizing the role of central cardiovascular changes.
• Training improves submaximal exercise efficiency and lactate metabolism in foxhounds.