The impact of repeated, local heating-induced increases in blood flow on lower limb endothelial function in young, healthy females

Abstract

Purpose: The purpose of the present study was to examine the effect of repeated, single leg heating on lower limb endothelial function.

Methods: Macrovascular function was assessed with superficial femoral artery (SFA) reactive hyperemia flow-mediated dilation (RH-FMD) and sustained stimulus FMD (SS-FMD). Calf microvascular function was assessed as the peak and area under the curve of SFA reactive hyperemia (RH). Participants (n = 13 females, 23 ± 2 yrs) had one leg randomized to the single leg heating intervention (EXP; other leg: control (CON)). The EXP leg underwent 8 weeks of single leg heating via immersion in 42.5 ℃ water for five 35-min sessions/week. At weeks 0, 2, 4, 6, and 8, SFA RH-FMD, SS-FMD (shear stress increased via plantar flexion exercise), and SFA RH flow were measured.

Results: None of the variables changed with repeated, single leg heating (interaction week*limb RH-FMD: p = 0.076; SS-FMD: p = 0.958; RH flow p = 0.955). Covariation for the shear stress stimulus did not alter the FMD results.

Conclusion: Eight weeks of single leg heating did not change SFA endothelial or calf microvascular function. These results are in contrast with previous findings that limb heating improves upper limb endothelial function.

Keywords: Flow-mediated dilation; Microvascular function; Reactive hyperemia; Superficial femoral artery; Sustained shear stress; Thermal therapy.