The cerebrovascular and executive function responses to increased inspiratory muscle work

The cerebrovascular and executive function responses to increased inspiratory muscle work

We investigated the cerebrovascular and executive function responses to increased inspiratory muscle work. Eight healthy men (33 ± 6 years) performed two separate 10 min bouts of inspiratory pressure threshold loading (ITL) targeting 70 % of maximal inspiratory mouth pressure (PImax) (ITL-Load) and two separate 10 min bouts of ITL targeting 2 % of PImax (ITL-Control). The order in which each participant undertook ITL-Load and ITL-Control conditions was randomized. Transcranial Doppler ultrasonography was used to measure middle cerebral artery blood velocity (MCAV) and executive function was measured using the trail making task (TMT) Parts A and B during the 4–6th min of ITL-Load and ITL-Control. The cerebrovascular conductance index (CVCi) and cerebrovascular resistance index (CVRi) were calculated. There were time x condition interactions (P < 0.01) for MCAV, CVCi and CVRi. This demonstrated during ITL-Load a small time-dependent increase (P < 0.01) in MCAV and CVCi, and a small time-dependent decrease (P < 0.01) in CVRi. Part A (P = 0.007) and Part B (P = 0.013) times for the TMT were slower for ITL-Load compared to ITL-Control. There were significant correlations between the change in MCAV from rest to the end of ITL and TMT times for Part A (r = 0.81, P = 0.009) and Part B (r = 0.67, P = 0.048). This is the first study to demonstrate that high-intensity ITL results in an increase in MCAV, and a decreased executive function measured by the TMT, and these two measures were related in that the increase in MCAV resulted in slower TMT times.