Related Experiment Videos
Increased hypoxic ventilatory sensitivity during exercise in man: are neural afferents necessary?
J J Pandit1, E Bergstrom, H L Frankel
1University Laboratory of Physiology, Oxford.
The Journal of Physiology
|May 15, 1994
Summary
Patients with spinal cord transection showed an increased acute ventilatory response to hypoxia during electrically induced leg exercise. This suggests exercise enhances hypoxic sensitivity even without volitional control or limb sensory input.
Area of Science:
- Physiology
- Neurology
- Respiratory Medicine
Background:
- Spinal cord injury (SCI) can impair autonomic and motor functions.
- Understanding respiratory control during exercise in SCI is crucial for rehabilitation and patient management.
Purpose of the Study:
- To investigate the acute ventilatory response to hypoxia (AHR) in individuals with complete spinal cord transection.
- To determine if electrically induced leg exercise (EEL) alters AHR in this population.
Main Methods:
- Nine patients with T4-T7 complete SCI underwent 3-minute hypoxia tests at rest and during EEL.
- EEL was achieved via surface electrodes stimulating quadriceps muscles.
- End-tidal PCO2 was maintained constant throughout the study.
Main Results:
- EEL increased metabolic CO2 production without significant changes in baseline ventilation.
- A significant increase in the acute ventilatory response to hypoxia was observed during EEL.
- Venous lactate levels remained stable, indicating minimal anaerobic metabolism.
Conclusions:
- Hypoxic sensitivity can increase during exercise in individuals with SCI, independent of volitional control.
- The findings suggest preserved neural pathways contributing to ventilatory control during exercise post-SCI.
- This highlights the potential for exercise to modulate respiratory responses even with significant neurological impairment.