Objective: To examine the acute changes in blood flow and blood pressure of very low load knee extensor exercise (15% one repetition maximum (1RM)) with and without different levels of applied pressure to determine how these effects might differ from high load exercise. We also sought to examine if this differed between men and women.
Approach: A total of 90 participants (45 men, 45 women) were randomized into a very low load condition with no restriction 15/0, (n = 21), a very low load condition with 40% arterial occlusion pressure (15/40, n = 23), a very low load condition with 80% arterial occlusion pressure (15/80, n = 22), and a traditional high load condition (70/0, n = 24). Pre-post change in blood flow and blood pressure were compared across conditions. Evidence for or against the null hypothesis was quantified using Bayes factors (BF10).
Main results: For blood flow, there was no evidence that the changes were different across conditions (BF10: 0.902). However, only the very low load free flow condition (15/0) had evidence to suggest a change (mean, (standard deviation)) from baseline (5.3 (9.1) ml · min-1; BF10: 3.687). Systolic pressure increased ~17 mmHg for the 15/0, 15/40, and 70/0 conditions, with no change in the 15/80 condition. There was no effect of sex for any variable.
Significance: There was substantial variability in our blood flow measurements, making conclusions difficult for this variable. Of note, the blood pressure response was not augmented by blood flow restriction. The hemodynamic changes were also similar between sexes, indicating that men and women were not changing differently.