Exercise-induced reductions in central command network cerebral blood flow assessed with arterial spin labeling MRI

Abstract

Habitual aerobic exercise positively impacts brain health. However, less is known about the acute effects of exercise on regional cerebral blood flow (CBF). Most studies have used exercise methods that required a 10-minute or longer delay before acquiring CBF data or methods that assessed global, rather than regional, CBF. In the current feasibility study, an aerobic exercise stimulus was administered using an MRI-compatible cardio step module connected to the MRI table. This allowed participants (N = 12, mean age = 20 years) to exercise at light-to-moderate intensity while in the bore of the MRI scanner. Pseudo-continuous arterial spin labeling MRI with multiple delays was collected on a 3T Siemens MRI scanner immediately pre- and post-exercise. CBF and arterial transit time changes were examined within the central command network, which impacts motor and cardiovascular systems during exercise. Associations with perceived exertion and cardiorespiratory fitness were assessed. CBF in central command regions decreased following exercise, with greater decreases in regions associated with cardiovascular control. For example, CBF in the left insula decreased by -9.03 ± 8.69 mL/100g/min (-11.45%, p < 0.01); CBF in the left and right rostral anterior cingulate decreased by -4.91 ± 6.08 mL/100g/min (-6.17%, p = 0.02) and by -5.04 ± 6.34 mL/100g/min (-7.43%, p = 0.02); and CBF in the left lateral orbitofrontal cortex decreased by -7.30 ± 8.11 mL/100g/min (-9.50%, p = 0.01). Decreased CBF was also associated with greater ratings of perceived exertion in cardiovascular command regions including right insula (r = -0.67, p = 0.03), medial orbitofrontal cortex (r = -0.64, p = 0.04), and lateral orbitofrontal cortex (r = -0.75, p = 0.01). The current study further demonstrates the feasibility of assessing CBF immediately following exercise using an exercise stimulus in the bore of the MRI scanner. These results contribute to a small but growing body of literature describing cerebral hemodynamics immediately following exercise.