The effect of cigarette smoking history on autonomic and cerebral oxygenation responses to an acute exercise bout in smokers.

The extent of smoking history is causally linked to adverse cerebro- and cardiovascular health outcomes, while conversely, exercise decreases this risk and associated mortality. However, the acute cerebro- and cardiovascular responses to exercise in smokers are unknown, and may provide insight to understand chronic adaptation. This study examined the acute heart rate (HR) variability (R-R intervals) and cerebral oxygenation responses to exercise in smokers compared to nonsmokers. Fifty-four males classified as smokers (n = 27) or nonsmokers (n = 27) were allocated into either younger (YSM, YNS) or middle-aged groups (MSM, MNS). Participants completed 40 min of stationary cycle ergometry at 50% of VO Cerebral oxygenation (near-infrared spectroscopy) and autonomic function (HR variability) were collected before, during, and after exercise at 0, 30 min, 1, and 4 hr postexercise. The nonsmoker cohort (MNS and YNS) demonstrated higher values for the standard deviation (SD) of the R-R interval (SDNN) and the root mean squared of the SD at 1 and 4 hr postexercise versus smokers (p < .05). The low frequency (LF) band in YSM was lower than in YNS at 1 hr (p < .05). However, LF and high frequency were higher for MNS compared to MSM at 1 hr (p < .05). Oxygenated hemoglobin during and following exercise were elevated in NS with values for MSM lower than YSM (p < .05). The findings show smoking history can affect cerebral oxygenation during and following an acute exercise bout. Further, following exercise, smokers may exhibit a delay or inhibition in parasympathetic activity.