Author(s): BIELITZKI, R., BEHRENDT, T., BEHRENS, M., LATENDORF, J.P., FRANZ, A., HUGHES, L., SCHEGA, L., Institution: UNIVERSITY OF HAMBURG, Country: GERMANY, Abstract-ID: 2657

INTRODUCTION:
In order to achieve the beneficial effects associated with the use of low external load blood flow restriction (BFR) training, it is recommended to apply a tourniquet cuff pressure of 40-80% of the individual arterial occlusion pressure (AOP). The AOP refers to the lowest pressure which is necessary to fully block arterial blood flow and can be affected by several factors (e.g., body position, limb circumference, systolic blood pressure). Generally, the AOP is determined in both limbs individually when performing bilateral BFR exercises, such as cycling, walking, or squats. However, since the tourniquet cuffs on both limbs are inflated simultaneously during bilateral BFR exercises, it is presently unknown whether the respective AOP must also be measured during bilateral tourniquet cuff inflation. To address this issue, the present investigation aimed to compare the AOP during unilateral versus bilateral tourniquet cuff inflation in the lower extremities.
METHODS:
Twenty-five young, healthy participants (8 females, 17 males, age: 24 ± 4 yrs, height: 176.0 ± 9.1 cm, weight: 73.4 ± 10.7 kg, body mass index: 23.6 ± 2.3 kg/m2) underwent one laboratory visit during which their individual AOP was determined using a standardized cuff inflation protocol and identified at the posterior tibial artery via Doppler ultrasound. In a randomized cross-over design, the AOP measurements were performed in supine, seated, and standing position starting with either unilateral or bilateral cuff inflation with a rest period of 5 min between assessments to restore homeostasis after change of body position. At the end of each AOP determination, blood pressure and heart rate were recorded. A 2 × 3 repeated measures analysis of variance was conducted for AOP, blood pressure, and heart rate. Mean differences (MD) and 95% confidence intervals (95%CI) were reported, with a significance level set at p < 0.05. Effect size Cohen’s d (d) was calculated and interpreted as trivial (d < 0.2), small (0.2 ≤ d < 0.5), medium (0.5 ≤ d < 0.8), and large (d ≥ 0.8).
RESULTS:
Across body positions, the AOP was higher during bilateral compared to unilateral tourniquet cuff inflation (MD = 3.2 mmHg [95%CI: 1.0, 5.4], p = 0.006, d = 0.12). In addition, AOP and heart rate increased as body position changed from supine to seated to standing position (p < 0.001, d = 0.76–1.94) while no differences were found for systolic blood pressure (p ≥ 0.373).
CONCLUSION:
Although statistically significant, the effect size for the difference between AOP during unilateral and bilateral tourniquet cuff inflation was only trivial. Thus, it does not appear necessary to determine AOP during bilateral tourniquet cuff inflation when performing bilateral BFR exercises. However, these results solely apply to young, healthy individuals and need to be verified for different inflation protocols, devices (i.e., manual versus automatic AOP determination), and populations (e.g., older adults, patients).