Introduction
Due to an increasing elderly population we are witnessing a corresponding increase in the burden of neurovascular disease. In response to this there is now a growing interest in preventative measures, such as exercise programs to combat these conditions and protect cerebrovascular health. High intensity interval exercise (HIIE) has been shown to be equally, if not more effective than moderate intensity continuous training (MICT) at improving peripheral vascular health despite its shorter time commitment. However, the effect of HIIE on cerebrovascular circulation is unclear. Therefore this study aimed to measure the middle cerebral artery blood velocity (MCAv) response during 30 min bouts of MICT and HIIE of two different intensities in middle aged adults.
Method
The moderate intensity continuous training (MICT) consisted of 30 Minutes of continuous exercise at 90% of GET. High intensity interval exercise 1 (HIIE1) consisted of 10 repetitions of 1 minute on 1 minute off at 70% of delta and high intensity interval exercise 2 (HIIE2) consisted of 4 minutes on 3 minutes off at 20% of delta.
Participants were medically screened and initially completed 1 preliminary session to assess their maximal aerobic capacity (V̇ O2max) and cognitive function (executive function and verbal and visual memory) before their 3 time-matched (30 min) experimental visits which were completed in random order at TCD. Measurements of Transcranial Doppler-determined middle & posterior cerebral artery blood flow velocity, brain oxygenation, blood pressure and end-tidal PCO 2 were taken continuously. In addition, 10 min & 1 h after these 3 bouts cerebrovascular reactivity (CVR) and dynamic cerebral autoregulation (dCA) were quantified. Due to the time constraints within my project for my poster, I focused on MCAv during the exercise bouts and did not consider pre and post measurements.
Data Analysis
MCAv was exported second by second during MICT, HIIE 1 and HIIE 2 exercise bouts. Mean MCAv, peak MCAv and area under the curve was calculated for each of the 17 participants.
Statistical analysis
One way repeated measures ANOVA explored the effect of MICT, HIIE 1 and HIIE 2 on mean MCAv, peak MCAv and AUC during the exercise bouts
Results
There was no significant difference in Mean MCAv (P = 0.71), MCAv peak (P = 0.20) or MCAv AUC (P = 0.71) among MICT, HIIE-1 and HIIE-2 exercise modalities.
Conclusion
These findings demonstrate that there is no difference between mean MCAv, MCAv peak and MCAv AUC during moderate-intensity continuous and high-intensity intermittent exercise in inactive middle aged adults. This demonstrates that despite a shorter period of activity HIIE can be as effective at stimulating cerebrovascular blood flow. Further research is needed to look at these effects on clinical populations with cerebrovascular risk factors such as type two diabetics.
Acknowledgements
Thank you to the Laidlaw Undergraduate Leadership and Research project team for their guidance and funding. My sincere thanks to my supervisors Dr. Mikel Egana, Dr. Max Weston and Dr. Norita Gildea for their support and advice throughout my project