Is the voluntary control of exercise in man necessary for the ventilatory response?

Abstract

SUMMARY1. The ventilatory response to electrically induced exercise (EEL) was studied in eighteen normal subjects and compared with the response to performing the same exercise voluntarily (EV).2. EEL was produced by surface electrode stimulation of the quadriceps and hamstring muscles so as to cause a pushing movement at 1 Hz against a spring load; this produced no pain or discomfort. Matching of Ev to EEL was achieved by subjects copying a tension signal recorded during EEL and displayed on a storage oscilloscope.3. There were no differences between the resting states measured before either form of exercise.4. The ventilatory response (change in ventilation as a ratio of the change in CO2 elimination) was similar in the two types of exercise. The increases in ventilation and CO2 elimination were greater with EEL. Small but significant increases in the gas exchange ratio and serum lactate were found for EEL but not for Ev, suggesting an increase in anaerobic metabolism in EEL. End-tidal PcO, showed little change in either form of exercise. In some runs end-tidal PCO2 rose, but insufficiently to account for the ventilatory response as judged by the response to inhaled CO2.5. In two subjects arterial blood samples showed small and inconsistent changes in both Paco, and Pao2 for Ev and EEL. pH and base excess changes also were consistent with more anaerobiosis with EEL compared to Ev.

The role of spinal cord transmission in the ventilatory response to exercise in man.

“…The ventilatory response to electrically induced exercise was studied in thirteen patients with traumatic spinal cord transaction at or about the level of T6. The steady-state and on-transient responses to this exercise were compared with those obtained in eighteen normal subjects (Adams, Garlick, Guz, Murphy & Semple, 1984).…”

“…The experiments described in the previous paper (Adams, Garlick, Guz, Murphy & Semple, 1984) suggest that neither the cortex, nor other higher centres within the central nervous system are necessary for the normal matching of ventilation to CO2 elimination in man exercising below the anaerobic threshold. However, it is possible that some afferent information from the exercising muscles associated with their movement or the development of tension, could still play an important role in making ventilation appropriate to the amount of exercise.…”

“…The experimental set-up and stimulating techniques used are described in the preceding paper (Adams et al 1984); the only differences were in allowances made for patients' incapacities. Consequently, the patients' feet were tied firmly to the pedals and their knees tied loosely together.…”

“…The present study investigates the ventilatory response in man with cord transection, using electrical stimulation of the paralysed muscles as described in the previous paper (Adams et al 1984). We wished to know whether and how ventilation increases as limbs are exercised without any sensory information from the exercising limb.…”

Abraham (“Abe”) Guz: a life devoted to breathing and breathlessness

“…This integrated service allowed free interactions between clinicians and researchers and was key to some of the later work. Abe continued studies on breathlessness in health and disease with studies of the genesis of exercise hyperpnoea [3], of functional brain mapping in breathing [4], of breathing control in heart-lung transplant patients [5], of the effect of local anaesthesia of the airways [6], and of exploring the patient descriptors of breathlessness and its measurement [7]. He also evaluated pharmaco-and psycho-therapeutic approaches to relieve the unpleasant sensation of dyspnoea [8,9].…”