Blood-flow-restriction (BFR) training is recently progressively applied in functional training settings. The optimal cuff pressure during BFR exercise, current literature recommends using percentages of each individual's arterial occlusion pressure (AOP). Most frequently, blood flow is determined by Doppler ultrasound (DU) techniques. Despite its high accuracy, the practicability of this gold standard is limited and time-consuming. An alternative solution to assess blood volume changes and pulse is pulse oximetry (PO). It was hypothesized that measurement of AOP could simplify the determination of cuff pressure during BFR training. Therefore, the main purpose of this study was to evaluate the accuracy of the PO for measuring the AOP compared to the current gold standard DU.

Thirty-five subjects (27.7±2.9 years) were enrolled in the study. Participants were positioned in a supine position and a 12-cm-wide cuff was applied in a counterbalanced order at the most proximal portion of the right upper and lower limb. The cuff pressure was then successively increased until the systolic pulse wave was no longer detected by DU and PO, respectively.

The results show that the mean values of AOP were 145.7±19.1mmHg and 144.0±26.4mmHg for the upper limbs, 191.5±24.1mmHg and 174.5±28.3mmHg for the lower limbs tested by DU and PO respectively (Fig. 1). Significant differences (paired t-test) between the two methods were revealed for the lower limbs (P=0.000) but not for the upper limbs (P=0.621).

Our results indicate that, compared with the gold standard DU, the PO method has statistically acceptable accuracy when measuring AOP in upper limbs. However, in lower extremities the PO significantly underestimates the actual AOP. This must be considered when implementing PO as a method for determining cuff pressure for BFR exercise.