Descending motor drive does not interact with muscle metaboreflex for ventilation regulation during rhythmic exercise in healthy humans

Author(s)

Gomes, Felipe S. ; Lopes, Thiago R. ; Bruce, Richard M. ; Silva, Bruno M.

• Document type: Journal article
• Source: AMERICAN JOURNAL OF PHYSIOLOGY-LUNG CELLULAR AND MOLECULAR PHYSIOLOGY; v. 327, n. 5, p. 13-pg., 2024-11-10.

Abstract

The muscle metaboreflex effect on pulmonary ventilation (VE) regulation is more apparent during rhythmic exercise than rest, possibly because this reflex interacts with other mechanisms regulating VE during voluntary contractions, such as central command. Therefore, we tested whether one part of central command, the descending component of motor execution (i.e., descending motor drive), and the muscle metaboreflex interact synergistically to regulate VE. Thirteen healthy adults (9 men) completed four experiments in random order under isocapnia. The muscle metaboreflex was activated by rhythmic handgrip exercise at 60% maximal voluntary contraction (MVC) force with the dominant hand. Then, the muscle metaboreflex remained active during a 4-min recovery period via postexercise circulatory occlusion (PECO), or it was inactivated, maintaining free blood flow to the dominant upper limb. During the last 2 min of the handgrip exercise recovery, participants either performed rhythmic voluntary plantar flexion with the dominant leg at 30% MVC torque to generate descending motor drive or the dominant leg's calf muscles were involuntarily activated by electrical stimulation at a similar torque level (i.e., without descending motor drive). VE increased to a similar level during handgrip exercise in all conditions (approximate to 22 L/min, P = 0.364). PECO maintained VE elevated above recovery with free blood flow (approximate to 17 L/min vs. approximate to 13 L/min, P = 0.009). However, voluntary and involuntary plantar flexion with or without PECO evoked similar VE responses (Delta approximate to 4 L/min, P = 0.311). Therefore, an interaction between descending motor drive and muscle metaboreflex is not ubiquitous for VE regulation during rhythmic exercise. (AU)

• FAPESP's process: 23/07135-0 - Interaction between the central command and the muscle metaboreflex for the regulation of pulmonary ventilation during exercise in humans
• Grantee: Felipe Silva Gomes
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• FAPESP's process: 22/10295-7 - Interaction between the central motor command and muscle metaboreflex for the regulation of pulmonary ventilation during exercise in humans
• Grantee: Felipe Silva Gomes
• Support Opportunities: Scholarships in Brazil - Master