The influence of time on determining blood flow restriction pressure

The influence of time, manifested in the oscillatory nature of physiology, has been documented in many processes. Within blood flow restriction literature, the restrictive stimulus is often applied based on a single arterial occlusion measurement, which is closely related to brachial systolic blood pressure (bSBP). Considering the oscillatory nature of bSBP, it is likely that time also influences arterial occlusion measurements.

To investigate the influence of time, within and between days, on arterial occlusion pressure and to determine whether the variability resembles the oscillatory pattern of bSBP.

Test-retest.

Twenty-two participants completed four testing sessions at 08:00 and 18:00h, 48h apart. Arm circumference, bSBP, and brachial diastolic blood pressure (bDBP) were measured at rest. Arterial occlusion pressure was determined using a cuff inflated on the proximal portion of the upper arm, with a Doppler probe placed over the radial artery.

Significant differences [mean (SD)] were observed for arterial occlusion pressure between Morning Day 2 [132 (14) mmHg, p<0.05], and all other visits [Morning Day 1: 138 (16); Evening Day 1: 139 (17); Evening Day 2 138 (14) mmHg]. A time effect was observed for bSBP, with a post-hoc test revealing that Morning Day 2 was different from all other visits.

Our findings suggest that arterial occlusion pressure is influenced by the time of day. As such, multiple occlusion measurements across an experiment may be necessary in order to account for potential oscillations in pressure and provide the intended relative restrictive stimulus.