Sex differences in dynamic cerebral autoregulation responses to resistance and endurance training in humans

Exercise maintains brain health and reduces the risk of cerebrovascular diseases, such as stroke and dementia. The benefits of different 'modalities' of exercise on male and female cerebral autoregulation are unclear. In this study, we compared adaptations in dynamic cerebral autoregulation (dCA) during spontaneous and forced oscillations in blood pressure between males and females following endurance (END) and resistance (RES) training. Using a randomized cross-over design, 49 healthy adults were recruited to participate in 3 months of END and RES training, with 3 months of washout. Middle cerebral artery blood velocity (MCAv) was measured using transcranial Doppler. The dCA was assessed using spontaneous (at rest) and forced oscillations in blood pressure (squat-stands) in the low-frequency band (0.167 and 0.083 Hz). At baseline, females had lower end-tidal partial pressure of CO₂, higher MCAv and higher gain than males (all P < 0.01). On a group level, there was a significant reduction in gain following RES but not END training during spontaneous dCA and forced dCA (all P < 0.05). When sexes were analysed separately, this reduction was apparent in females, but not in males. Furthermore, females had a significant reduction in normalized gain during spontaneous dCA and forced dCA at 0.167 Hz. This study is the first to assess sex differences in dCA using a randomized cross-over design involving supervised exercise of two distinct modalities. We found that RES training might be more beneficial than END training for improving dCA in young healthy individuals, and this is apparent across multiple methods of measuring dCA. This benefit is more apparent in females.