High-Intensity Exercise Mitigates Cardiovascular Deconditioning During Long-Duration Bed Rest

Figures

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  Figure 1. Study design and timeline of data collection. HDT, head-down tilt; TRAIN, reactive jumps training; BDC−7, Baseline Data Collection (7 days before start of HDT); R+10, Recovery data collection (10 days after the end of HDT); Sup, measurements in supine position; Sit, measurements in sitting position.

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  Figure 2. (A–F) Time courses of hemodynamic variables for CTRL (red circles) and TRAIN (blue triangles) groups. Measurements time points in supine position: 7 days before (BDC−7) and 10 days after (R+10) HDT, and on the 2nd (HDT2), 28th (HDT28) and 56th (HDT56) day of HDT. Data are presented as marginal means ± SE of percent changes from baseline values (with BDC−7 supine = 100%) at each time point. Colored asterisks indicate significance compared to BDC−7 within the single group. Black asterisks show significant difference from baseline in the whole sample of participants (when only the factor Time - and not the factor Group or their interaction - is significant). The pound sign denotes significant differences between groups at each time point. (A) HR, Heart Rate; (B) SV, Stroke Volume; (C) CO, Cardiac Output; (D) TPR, Total Peripheral Resistance; (E) SBP, Systolic Blood Pressure; (F) DBP, Diastolic Blood Pressure. ***p < 0.001, **p < 0.01, *p < 0.05, #p < 0.05.

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  Figure 3. (A–F) Time courses of autonomic variables for CTRL (red circles) and TRAIN (blue triangles) groups. Measurements time points in supine position: 7 days before (BDC−7) and 10 days after (R+10) HDT, and on the 2nd (HDT2), 28th (HDT28) and 56th (HDT56) day of HDT. Data are presented for each time point as marginal mean ± SE of differences with respect to baseline supine position (for spectral powers, BDC−7 supine = 0) or of percent changes from baseline supine position (for DFA1, BDC−7 supine = 100%). Colored asterisks indicate significance compared to BDC−7 within the single group. RRI, R-R intervals; (A) HF, High-Frequency power; (B) LF, Low-Frequency power; (C) VLF, Very-Low-Frequency power; (D) DFA1, short-term fractal index by detrended fluctuations analysis; (E) LF of DBP: Low-Frequency power of Diastolic Blood Pressure; (F): LF/HF, Low-Frequency to High-Frequency powers ratio ***p < 0.001, **p < 0.01, *p < 0.05.

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  Figure 4. (A–F) Delta scores of hemodynamic variables, i.e., the difference (Δ) between the value measured before bed rest (at BDC−7) and the corresponding value measured after bed rest (at R+10, see text) for the supine (Sup) and the sitting (Sit) position: adjusted means ± SE. For each panel: control group (CTRL) red bars on the left-hand side, and training group (TRAIN) blue bars on the right-hand side. Asterisks above whiskers indicate delta scores significantly different from zero. Horizontal lines with asterisks indicate significant differences between supine and sitting delta scores within the same group. Pound signs indicate significant differences between groups at the same position. (A) HR, Heart Rate; (B) SV, Stroke Volume; (C) CO, Cardiac Output; (D) TPR, Total Peripheral Resistance; (E) SBP, Systolic Blood Pressure; (F) DBP, Diastolic Blood Pressure. ***p < 0.001, **p < 0.01, *p < 0.05, ##p < 0.01, #p < 0.05.

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  Figure 5. (A–D) Delta scores of autonomic variables, i.e., the difference (Δ) between the value measured before bed rest (at BDC−7) and the corresponding value measured after bed rest (at R+10, see text) for the supine (Sup) and the sitting (Sit) position: adjusted means ± SE. For each panel: control group (CTRL) red bars on the left-hand side, and training group (TRAIN) blue bars on the right-hand side. Asterisks above whiskers indicate delta scores significantly different from zero. Horizontal lines with asterisks indicate significant differences between supine and sitting delta scores within the same group. Pound signs indicate significant differences between groups at the same position. RRI, R-R intervals; (A) HF, High-Frequency power; (B) LF/HF, Low-Frequency to High-Frequency powers ratio; (C) LF, Low-Frequency power; (D) DFA1, short-term fractal index by detrended fluctuations analysis. ***p < 0.001, *p < 0.05, #p < 0.05.