Exercise‐based cardiac rehabilitation is associated with a normalization of the heart rate performance curve deflection

Figures

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  Figure 1. Overview of the retrospective study design. Patients who exercised regularly during phase II and phase III of cardiac rehabilitation were defined as training group, and patients who stopped after phase II were served as control group. Gray arrows pointing downwards indicate incremental exercise tests with the measurement of cardiorespiratory fitness and the degree of heart rate performance curve deflection (K HR)

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  Figure 2. Effects of exercise training during phase II and phase III cardiac rehabilitation on heart rate performance curve (HRPC) deflection (K HR). A and B, Exemplary HRPCs. Time indicates the duration of an incremental exercise test. Blood lactate concentration after each step is used to determine LTP1 and LTP2. The region between LTP1 and the end of the exercise test (max) is used to determine K HR by fitting a quadratic function to the heart rate data and relating the slopes of tangents at LTP2 and max (dotted lines) to each other (A) Upward‐deflected HRPC indicated by positive K HR. B, Downward‐deflected HRPC indicated by negative K HR. C, Descriptive statistics. K HR values of each patient of the training group (n = 96) and the control group (n = 32) shown by thin, gray lines. Symbols indicate group means, and error bars show standard deviations. Horizontal arrows indicate the period in which regular exercise training was performed in each group. D, Inferential statistics. Estimated marginal K HR value means of both groups with 95% confidence intervals after adjustment for the potential confounders age, baseline body weight, baseline power output in watts, smoking status (yes/no),…

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  Figure 3. Effects of exercise training during phase II and phase III cardiac rehabilitation on power output, heart rate, and blood lactate concentration. A, Power output at lactate turn points 1 and 2 (LTP1 and LTP2) and maximum values after adjustment for the potential confounders age, smoking status (yes/no), and the use of β‐blockers (yes/no). B, Heart rate at rest, at LTP1, LTP2, and maximum values. Plotted estimated marginal means are adjusted for the potential confounders age, baseline body weight, baseline power output in watts, smoking status (yes/no), and the use of β‐blockers (yes/no). C, Blood lactate concentrations at rest, at LTP1, LTP2, and maximum values. Plotted estimated marginal means are adjusted for the potential confounders age, baseline body weight, baseline power output in watts, smoking status (yes/no), and the use of β‐blockers (yes/no). For all plots, significant time × group interactions indicate that groups developed differently concerning the dependent variable throughout the respective phases of rehabilitation. Significant effects of time indicate that the dependent variable changed in both groups during the respective phase of rehabilitation. *P < 0.05, **P <…

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  Figure 4. Relationship between intra‐individual changes in cardiorespiratory fitness and changes in the degree of HRPC deflection. Each thin line represents data of a single patient and includes data of three time points. Thick lines are regression lines, with corresponding equations below. Partial correlation coefficients indicate the strength of the association between changes in power output and K HR. A, Relationship between changes in power output at LTP1 and changes in K HR. B, Relationship between changes in power output at LTP2 and changes in K HR. C, Relationship changes in maximal power output and changes in K HR. Horizontal brackets and P‐values refer to the hypothesis that plotted correlations differ concerning their strength (ie, partial r)