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Respiratory muscle reserve in rats during heavy exercise
L E Gosselin1, D Megirian, J Rodman
1Department of Physical Therapy, Exercise, and Nutrition Sciences, State University of New York at Buffalo, Buffalo, New York 14214, USA. gosselin@acsu.buffalo.edu
Journal of Applied Physiology (Bethesda, Md. : 1985)
|October 24, 1997
Summary
Respiratory muscles are key for exercise capacity. In rats, losing one hemidiaphragm had no effect, but losing both significantly reduced peak oxygen consumption (VO2 peak).
Area of Science:
- Physiology
- Exercise Physiology
- Respiratory Physiology
Background:
- Maximal aerobic capacity can be limited by respiratory muscle function.
- The specific contribution of the diaphragm to exercise capacity in quadrupeds remains incompletely understood.
Purpose of the Study:
- To investigate the impact of reduced respiratory muscle reserve on maximal aerobic capacity.
- To determine if diaphragm denervation affects peak oxygen consumption (VO2 peak) in rats.
Main Methods:
- Whole body peak oxygen consumption (VO2 peak) was measured in rats using a graded treadmill test.
- Surgical interventions included Sham, unilateral, or bilateral hemidiaphragm denervation (Dnv).
- Hemidiaphragm paralysis was confirmed by electromyography post-testing.
Main Results:
- Before surgery, VO2 peak values were similar across all groups (approx. 86-92 ml.kg-1.min-1).
- Two weeks post-surgery, VO2 peak remained unchanged in Sham and unilateral Dnv groups.
- Bilateral Dnv resulted in a significant 19% decrease in VO2 peak.
Conclusions:
- The respiratory system in rats demonstrates resilience, with compensatory capacity for unilateral diaphragm loss during heavy exercise.
- Complete hemidiaphragm paralysis significantly impairs maximal aerobic capacity, indicating the diaphragm's crucial role.
- These findings highlight the diaphragm's importance as a limiting factor in exercise performance when its function is substantially compromised.