Countdown before voluntary exercise induces muscle vasodilation with baroreflex-mediated decrease in muscle sympathetic nerve activity in humans

Abstract

We examined whether countdown (CD) before voluntary bicycle ergometer exercise induced cerebro‐cardiovascular responses and, if so, whether these responses to CD were altered by postural change from the semi‐recumbent to supine position. Young men (n=14) performed voluntary cycle exercise in the semi‐recumbent position while middle cerebral artery blood flow velocity (CBF; Doppler ultrasonography), heart rate (HR), blood pressure (finger photoplethysmography), oxygen consumption rate (VO2), oxygen saturation in the right thigh muscle (StO2; near‐infrared spectrometry), cardiac output (CO; cZ method) and total peripheral resistance (TPR) were measured. The subjects repeated 8 trials, intermitted by more than 5‐min rest. In 4 trials randomly selected from 8 trials, the onset of exercise was signaled by a 30‐sec CD, whereas in the remaining 4 trials, exercise was started without CD. We found that CD increased CBF, HR, CO, mean blood pressure, and VO2 sequentially, decreasing TPR with increased StO2. To assess efferent signals causing vasodilation and the effects of posture change from the semi‐recumbent to supine position, other groups of subjects underwent the same exercise protocol but using only right leg in the semi‐recumbent (n=10) or supine (n=8) positions while muscle sympathetic nerve activity (MSNA; microneurography) and StO2 were measured in the left and right leg, respectively. We found that CD decreased MSNA burst frequency and total MSNA (both, P<0.05), which were significantly correlated with the increase in StO2 (both, P<0.001). However, these responses to CD were nearly abolished by the postural change. Thus, CD before starting voluntary exercise induced cerebro‐cardiovascular responses from central system to effector organs in a sequential manner in the semi‐recumbent position, but these responses were minimized while in the supine position. Support or Funding Information This study was supported by grants from the Japan Society for the Promotion of Science (24689014 and 15H04680). This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Sympathetic neural reactivity to the Trier social stress test

“…Interestingly, the sympathetic response to preparatory or anticipatory stress appears to be governed by both the stressor type as well as psychological factors. For example, Manabe et al (2020) observed a significantly blunted MSNA response to a countdown prior to exercise initiation, while Brown et al (2013) observed significantly increased MSNA in response to passive viewing of exercise. Further, Holwerda et al (2018) reported significantly elevated peripheral sympathetic outflow in individuals with generalized anxiety disorder during the anticipatory phase prior to mental stress, as well as throughout the stressor itself.…”

“…Many commonly utilized stress tests are performed with the addition of multiple confounds such as irregular breathing patterns and depth, active talking, muscle movements and other confounds that may impact MSNA recordings and subsequent data interpretation. Recently, anticipatory stress has been shown to significantly impact sympathetic outflow in both healthy individuals (Brown et al., 2013; Manabe et al., 2020) and those with generalized anxiety disorder (Holwerda et al., 2018). Interestingly, the sympathetic response to preparatory or anticipatory stress appears to be governed by both the stressor type as well as psychological factors.…”

“…For example, Manabe et al. (2020) observed a significantly blunted MSNA response to a countdown prior to exercise initiation, while Brown et al. (2013) observed significantly increased MSNA in response to passive viewing of exercise.…”

“…Many common experimental mental stress tasks are performed in the presence of confounds that may impact sympathetic reactivity, including irregular breathing patterns, active talking and muscle movement. Recent studies have begun to assess the influence of anticipatory stress on sympathetic control of cardiovascular function (Brown et al., 2013; Holwerda et al., 2018; Manabe et al., 2020). Specifically, anticipatory stress may be able to distinguish the effects of trait psychological characteristics on sympathetic reactivity to stress (Bigalke & Carter, 2021; Holwerda et al., 2018).…”

Role of linkage between cerebral activity and baroreflex control of heart rate via central vasopressin V1a receptors in food-deprived mice

“…Recently, we reported similar responses in humans when they intended to start exercise, which were followed by enhanced muscle blood flow and oxygen consumption rate at the onset of exercise (22). Thus, these responses are thought to be one of the feed-forward mechanisms for adjusting cardiovascular functions for starting voluntary exercise smoothly (23).…”