Innovative Dose–Response Assessment of the Metaboreflex With Indirect Control of Intramuscular Metabolic Perturbation in Humans

Figures

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  FIGURE 1. Sex differences and reproducibility in neuromuscular fatigue across the four bouts of post‐exercise circulatory occlusion. Panels (A–C) show sex difference data from males (closed circles; n = 15) and females (open circles; n = 15). Panels (D–F) show reproducibility data from visit 1 (closed squares; n = 28) and visit 2 (open squares; n = 28). For technical reasons, we did not assess the reproducibility of 2 participants. ∆MVC and ∆QTW are expressed as percentage change from baseline; voluntary activation is expressed in absolute values. MVC, maximal voluntary contraction peak force; QTW, Quadriceps potentiated twitch force; VA, voluntary activation; PECO, post‐exercise circulatory occlusion. Data are presented as group means (bars) and individual values (symbols), and were analyzed using two‐way ANOVA. *p < 0.05, **p < 0.01, ***p < 0.001 males versus females.

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  FIGURE 2. Sex differences and reproducibility in blood pressure responses across the four exercises and post‐exercise circulatory occlusion bouts. Panels (A) and (B) show sex difference data from males (closed circles; n = 15) and females (open circles; n = 15). Panels (C) and (D) show reproducibility data from visit 1 (closed squares; n = 28) and visit 2 (open squares; n = 28). ∆MAP is expressed as percentage change from baseline. MAP, mean arterial pressure; PECO, post‐exercise circulatory occlusion. Data are presented as group means (bars) and individual values (symbols) and were analyzed using two‐way ANOVA.

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  FIGURE 3. Sex differences and reproducibility in cardiovascular responses across the four bouts of post‐exercise circulatory occlusion. Panels (A–D) show sex difference data from males (closed circles; n = 15) and females (open circles; n = 15). Panels (E–H) show reproducibility data from visit 1 (closed squares; n = 28) and visit 2 (open squares; n = 28). ∆HR, ∆CO, ∆TPR and ∆SV are expressed as percentage change from baseline. HR, heart rate; CO, cardiac output; PECO, post‐exercise circulatory occlusion; SV, stroke volume; TPR, total peripheral resistance. Data are presented as group means (bars) and individual values (symbols), and were analyzed using two‐way ANOVA.

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  FIGURE 4. Sex differences and reproducibility in the linear relationships between mean arterial pressure and quadriceps twitch force. Data are presented as mean ± SD and expressed as percentage change from baseline. Panel (A) shows sex difference data from males (closed circles; n = 15) and females (open circles; n = 15). Panel (B) shows reproducibility data from visit 1 (closed squares; n = 28) and visit 2 (open squares; n = 28). Associations were tested using linear multilevel models with a random intercept. MAP, mean arterial pressure; PECO, post‐exercise circulatory occlusion; QTW, quadriceps potentiated twitch force.

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  FIGURE 5. Sex differences and reproducibility in blood pressure response to post‐exercise circulatory occlusion with indirect control of intramuscular metabolic perturbation. Panel (A) shows sex difference data from males (closed circles; n = 15) and females (open circles; n = 15). Panel (B) shows reproducibility data from visit 1 (closed squares; n = 28) and visit 2 (open squares; n = 28). Metaboreflex gain was calculated as the ratio of ∆MAP during PECO to ∆QTW measured post PECO. MAP, mean arterial pressure; PECO, post‐exercise circulatory occlusion; QTW, Quadriceps potentiated twitch force. Data are presented as group means (bars) and individual values (symbols), and were analyzed using two‐way ANOVA. Horizontal black lines represent the group means for clarity.

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  FIGURE 6. Bland–Altman plots representing test–retest reproducibility between visit 1 and visit 2 for blood pressure response to post‐exercise circulatory occlusion with indirect control of intramuscular metabolic perturbation. Data are presented in planels (A–D) from PECO 1 to 4, respectively, and expressed as the ratio between ∆MAP during PECO to ∆QTW measured post PECO (closed circles; n = 28). For technical reasons, we did not assess the reproducibility of 2 participants. For each panel, the difference between visit 1 (V1) and visit 2 (V2) is plotted against the mean of visit 1 and visit 2. The solid horizontal line represents the mean difference, with the corresponding values indicated above the line. The dotted lines represent the limits of agreement (mean ± 1.96 SD). MAP, mean arterial pressure; PECO, post‐exercise circulatory occlusion; QTW, quadriceps potentiated twitch force.

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  FIGURE 7. Group and representative samples of blood pressure response data collected during post‐exercise circulatory occlusion with or without indirect control of intramuscular metabolic perturbation. In panel (A), data are expressed as percentage change from baseline (∆MAP), while in panel (B), data are expressed as ratios between ∆MAP and ∆QTW. Data are presented as group means (bars) and individual values (circles) and were analyzed using independent t‐tests. Panels (C–F) show representative data from two pairs of participants illustrating how the two approaches can yield different conclusions. Participants 1 and 2 show different ∆MAP responses (+68.4 vs. 44.5%) but similar ∆MAP normalized to ∆QTW (1.65 vs. 1.64), whereas participants 3 and 4 show similar ∆MAP responses (+24.5 vs. 24.6%) but different ∆MAP normalized to ∆QTW (3.29 vs. 1.45).