Reproducibility of four frequently used local heating protocols to assess cutaneous microvascular function.
Skin microvascular responses to local heating are frequently used to assess microvascular function. Several local heating protocols have been developed, all varying slightly in execution. The aim of this study was to determine the inter-day reproducibility of the four most commonly used local heating protocols in healthy young subjects.



Fifteen, healthy males (28±5yrs, BMI 25±2kg/m2) attended two experimental trials 2-7days apart. During each trial, baseline and maximal thermally stimulated forearm skin responses were examined simultaneously at four sites on the dominant forearm using laser Doppler flowmetry (LDF). The following heating protocols were adopted: 1. Rapid 39°C (0.5°C/5s), 2. Rapid 42°C (0.5°C/5s) 3. Gradual 42°C (0.5°C/2min 30s) and 4. Slow 42°C (0.5°C/5min). The coefficient of variation (CV) was calculated for absolute flux, cutaneous vascular conductance (CVC; flux/mean arterial pressure, MAP) and CVC expressed as a percentage of maximal CVC at 44°C (%CVCmax) at three different time points; baseline (33°C), plateau (39/42°C) and maximal (44°C).



Reproducibility of baseline flux, CVC and %CVCmaxwas 17-29% across all protocols. During the plateau, Rapid, Gradual and Slow 42°C demonstrated a reproducibility of 13-18% for flux and CVC and 5-11% for %CVCmax. However, Rapid 39°C demonstrated a lower reproducibility for flux, CVC and %CVCmax(all 21%). Reproducibility at 44°C was 12-15% for flux and CVC across all protocols.



This is the first study examining inter-day reproducibility across four local heating protocols. The good-to-moderate reproducibility of the Rapid, Gradual and Slow 42°C protocols support their (simultaneous) use to assess microvascular function. Using Rapid 39°C may require a greater number of subjects to detect differences within subjects.
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
Kirsty A
KA
Roberts
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK; Radboud Institute for Health Sciences, Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands.
Thijs
T
van Gent
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
Nicola D
ND
Hopkins
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
Helen
H
Jones
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK.
Ellen A
EA
Dawson
Unilever Research & Development, Olivier van Noortlaan 120, 3133 AT Vlaardingen, The Netherlands.
Richard
R
Draijer
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK; School of Sport Science, Exercise and Health, The University of Western Australia, Crawley, Western Australia 6009, Australia.
Howard H
HH
Carter
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK; School of Sport Science, Exercise and Health, The University of Western Australia, Crawley, Western Australia 6009, Australia.
Ceri L
CL
Atkinson
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK; School of Sport Science, Exercise and Health, The University of Western Australia, Crawley, Western Australia 6009, Australia.
Daniel J
DJ
Green
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK; Radboud Institute for Health Sciences, Department of Physiology, Radboud University Medical Center, Nijmegen, The Netherlands.
Dick H J
DHJ
Thijssen
Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, UK. Electronic address: d.a.low@ljmu.ac.uk.
David A
DA
Low
D000328:Adult; D001783:Blood Flow Velocity; D006801:Humans; D006979:Hyperthermia, Induced / Q000379:methods*; D017078:Laser-Doppler Flowmetry; D008297:Male; D008833:Microcirculation; D055806:Microvessels / Q000502:physiology*; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D012867:Skin / Q000098:blood supply*; D012881:Skin Temperature; D013997:Time Factors; D055815:Young Adult
Endothelial function; Local heating; Microvasculature; Nitric oxide; Skin microcirculation