Contribution of blood oxygen and carbon dioxide sensing to the energetic optimization of human walking

In this study we tested the hypothesis that an important source of energetic cost measurements arises from blood gas receptors that are sensitive to O2 and CO2 concentrations. These receptors are known to play a role in regulating other physiological processes related to energy consumption, such as ventilation rate. Given the role of O2 and CO2 in oxidative metabolism, sensing their levels can provide an accurate estimate of the body’s total energy use. To test our hypothesis, we simulated an added energetic cost for blood gas receptors that depended on a subject’s step frequency and determined if subjects changed their behavior in response to this simulated cost. These energetic costs were simulated by controlling inspired gas concentrations to decrease the circulating levels of O2 and increase CO2. We found this blood gas control to be effective at shifting the step frequency that minimized the ventilation rate and perceived exertion away from the normally preferred frequency, indicating that these receptors provide the nervous system with strong physiological and psychological signals. However, rather than adapt their preferred step frequency toward these lower simulated costs, subjects persevered at their normally preferred frequency even after extensive experience with the new simulated costs. These results suggest that blood gas receptors play a negligible role in sensing energetic cost for the purpose of optimizing gait.
NEW & NOTEWORTHY Human gait adap...

Source: Journal of Neurophysiology - August 14, 2017 Category: Neurology Authors: Wong, J. D., OConnor, S. M., Selinger, J. C., Donelan, J. M. Tags: Research Articles Source Type: research