Acute effects of high‐intensity interval training session and endurance exercise on pulmonary function and cardiorespiratory coupling

FIGURE 1. Experimental design. Physically active men (n = 4) and women (n = 4), performed 3 different randomly ordered protocols (HIIT, endurance exercise [EE] and control) in a treadmill. Before and after each experimental procedure individuals were assessed on: blood pressure, autonomic control, cardiorespiratory coupling, pulmonary function and orthostatic sit‐up test. HRmax, maximal heart rate

FIGURE 2. Acute effect of high‐intensity interval training and endurance exercise on pulmonary function. Summary data of pulmonary flow recording during forced expiration test. (a–c) Control, EE and HIIT, respectively, showed similar values of peak expiratory flow (PEF), forced expiratory volume at 1‐s (FEV1), forced expiratory flow at 25% (FEF 25), 50% (FEF 50) and 75% (FEF 75) of vital capacity (VC), FEF and FEV1/VC during control patients. Two‐way ANOVA with repeated measures followed by Holm‐Sidak post‐hoc test, median ± min‐max, n = 8

FIGURE 3. Acute effect of high‐intensity exercise training and endurance exercise on heart rate variability alterations in healthy individuals. (a) Representative spectrums of heart rate variability (HRV) in control conditions, EE and HIIT. Note that HIIT has an increase of low frequency (LF) of HRV, a decrease of high frequency (HF) of HRV and, consequently, an increase of LF/HF ratio. (b‐d) Summary quantification of LF, HF and LF/HF ratio of HRV, respectively. Two‐way ANOVA with repeated measures followed by Holm‐Sidak post‐hoc test, median ± min‐max, n = 8

FIGURE 4. Single bout of high‐intensity exercise training elicits sympathoexcitation in healthy individuals. (a) Representative recording of heart rate (HR) and power spectral density (PSD) of non‐stationary analysis of HR with 2‐s resolution (time varying domain of HR variability) during tilt. Note that post‐HIIT the low frequency (LF) component is increased and high frequency (HF) component is decreased. Control and endurance exercise did not show significant differences (b) Summary data of △HR between before and after tilt test. (c–e) Summary data of LF, HF and LF/HF ratio of HRV non‐stationary analysis, respectively. Twoway ANOVA with repeated measures followed by Holm‐Sidak post‐hoc test. Values are median ± min‐max n = 8

FIGURE 5. Single bout of endurance exercise increases cardiorespiratory coupling in healthy individuals. (a) Representative image of control condition, EE and HIIT before and after single bout of exercise on coupling oscillation between breath (B) and heart (H). Note that EE training results in an increase of physiological coupling after the exercise. There were no significant changes in control and HIIT. (b) Quantification of the effect of control, EE and HIIT on the coupling coefficient between B‐H (B → H). (c) Coupling coefficient between H‐B (H → B). Two‐way ANOVA with repeated measures followed by Holm‐Sidak post‐hoc test. Values are median ± min‐max, n = 8