Acute measurement of flow‐mediated dilation following passive heating in adults: The confounding role of altered shear stress and baseline vasodilation

Figures

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  FIGURE 1. Schematic representation of the change in brachial artery diameter in response to forearm occlusion and the calculation of the associated metrics of vasoactivity. Dbase, baseline diameter; Docc, diameter during the final 30 s of occlusion; Dpeak, peak diameter following cuff deflation; FMD, flow‐mediated dilation; FMDDocc, flow‐mediated dilation using end‐occlusion diameter instead of baseline diameter; OIV, occlusion‐induced vasoactivity.

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  FIGURE 2. Mean brachial artery diameter pre and post immersion during the FMD assessment for each condition. Dbase, baseline diameter; Docc, diameter during the final 30 s of occlusion; Dpeak, peak diameter following cuff deflation. Significance is denoted as follows: a40‐Shoulder versus 42‐Waist (Dbase p < 0.001, Docc p = 0.006, Dpeak p < 0.001), b40‐Shoulder versus 40‐Waist (Dbase p < 0.001, Docc p = 0.046, Dpeak p < 0.001), c42‐Waist versus 40‐Waist, *versus Pre in the 40‐Shoulder condition at the equivalent timepoint (Dbase p < 0.001, Docc p = 0.003, and Dpeak p < 0.001).

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  FIGURE 3. Mean adjusted indices of vasoactivity for each condition pre and post immersion. (a) FMD% (flow‐mediated dilation), (b) OIV% (occlusion‐induced vasoactivity), (c) FMDDocc% (flow‐mediated dilation using end‐occlusion diameter instead of baseline). Significance is denoted as follows: a40‐Shoulder versus 42‐Waist (FMD p = 0.013, OIV p = 0.004), b40‐Shoulder versus 40‐Waist (FMD p < 0.001, OIV p < 0.001, FMDDocc p = 0.001), c42‐Waist versus 40‐Waist (OIV p = 0.032), and *Pre versus Post in the same condition (40‐Shoulder: FMD p < 0.001, OIV p < 0.001, FMDDocc p = 0.029; 42‐Waist: OIV p = 0.024).

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  FIGURE 4. Repeated measures correlations between the changes pre – post immersion in selected indices of vasoactivity. (a) Dbase versus FMD%, (b) adjusted OIV versus FMD%, (c) Dbase versus OIV%, and (d) OIV% versus FMDDocc%. Smaller gray lines represent the rmcorr fit for each participant, with the dashed black line showing the group average. Dbase, baseline diameter; FMD%, flow‐mediated dilation; FMDDocc%, flow‐mediated dilation using end‐occlusion diameter instead of baseline; OIV%, occlusion‐induced vasoactivity.