Flow mediated vasodilation changes in older and younger adult groups after 4 weeks of low intensity hand grip isometric training with vascular occlusion
Low intensity blood flow restricted exercise (BFRE) has been shown to increase muscle strength similarly to high intensity (HI) exercise in young adults. This may be beneficial in older adults to attenuate sarcopenia but without the negative side effects of HI exercise. The purpose of this study was to compare brachial artery flow mediated dilation (FMD) before and after 4 weeks of low intensity isometric hand grip BFRE. The comparison will be between three cohorts, namely a young adult group with BFRE (YR), an older adult group with BFRE (OR) and an older adult group with HI exercise (OH). My hypothesis is that there will be a significant difference between FMD, brachial artery diameter and peak flow velocity responses to reactive hyperemia in YR and OR as compared to OH after the 4-week training.
Eight individuals comprised YR, ten individuals comprised OR and nine individuals comprised OH. YR and OR performed low intensity (20% maximum voluntary contraction (MVC)) isometric handgrip training exercises during 5 minutes of BFRE three times weekly for 4 weeks. OH performed high intensity (75% MVC) isometric handgrip training exercises without blood flow occlusion. Before and after 4 weeks of training, resting brachial artery blood flow velocity and diameter, and peak brachial artery blood flow velocity and diameter during reactive hyperemia were measured. FMD as well as shear rate (SR) were calculated for all groups.
No significant differences were found between brachial artery diameter and peak blood flow velocity during reactive hyperemia, nor for FMD and SR, when compared before and after training for individual subjects. Neither were any significant differences found for these parameters between YR, OR, and OH groups.
Data from this study did not support the hypothesis nor other findings in the literature. The differences in these results may have been related to study design or implementation including variation in training type, intensity and frequency as well as accuracy of data collection. Several limitations of this study, including sonographer experience, small sample size, occult vascular aging changes and inconsistencies in ultrasound measurements due to timing and position, may have affected the results. Future studies controlling for these limitations may have a different outcome.