The Effect of Lower-Body Positive Pressure on the Cardiorespiratory Response at Rest and during Submaximal Running Exercise

Figures

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  Figure 1. Overview of the experimental protocols. Pressure levels were applied in a randomized order in both experiments. EXP-run: n = 9; EXP-rest: n = 10.

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  Figure 2. Changes in cardiorespiratory parameters over the LBPP periods during EXP-rest. Boxes extend from the 25th to 75th percentiles, upper and lower whiskers represent maximum and minimum values, respectively. N = 10; *different from baseline and steady-state (P < 0.05); ‡different from steady-state (P < 0.05). (Left) LBPP 15 mmHg. (Right) LBPP 40 mmHg. Acute, within first minute of LBPP; S-state, steady-state after three minutes of LBPP.

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  Figure 3. Representative example of tracings taken over the EXP-rest protocol. The dashed line marks the application of LBPP. From top to bottom: stroke volume (SV), heart rate (HR) and cardiac output (CO), oxygen consumption (VO2), and end-tidal PO2 (PETO2).

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  Figure 4. Representative example of tracings taken over the EXP-rest protocol. The dashed line marks the application of LBPP. (Top) Peripheral resistance (PR); (Bottom) mean arterial pressure (MAP).

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  Figure 5. Baroreflex sensitivity (BRS) at the onset of LBPP. Baroreflex sensitivity after application of LBPP at 15 (LBPP15) and 40 (LBPP40) mmHg compared to the corresponding baselines at 0 mmHg (BSL15 and BSL40, respectively) (n = 10). BRS is expressed as the ratio between standard deviations RRI/SBP. Boxes extend from the 25th to 75th percentiles, upper and lower whiskers represent maximum and minimum values, respectively. *Different from baseline (P < 0.05).

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  Figure 6. Cardiorespiratory parameters at exercise steady-state. Average steady-state values (±SD) at each pressure level (▲: 40 mmHg; ○: 15 mmHg; ■: control) as a function of oxygen uptake (VO2) (n = 9); (A) Cardiac output, CO; (B) Heart rate, HR; (C) Stroke volume, SV; (D) Peripheral resistance, PR; (E) Systemic arteriovenous oxygen difference, a-vDO2; (F) Mean arterial pressure, MAP. Systemic arteriovenous oxygen difference (a-vDO2) was calculated as oxygen uptake (VO2) divided by cardiac output (CO) for each level of lower body positive pressure and speed.