Exercise training intensity determination in cardiovascular rehabilitation: Should the guidelines be reconsidered?

AIMS: In the rehabilitation of cardiovascular disease patients a correct determination of the endurance-type exercise intensity is important to generate health benefits and preserve medical safety. It remains to be assessed whether the guideline-based exercise intensity domains are internally consistent and agree with physiological responses to exercise in cardiovascular disease patients. METHODS: A total of 272 cardiovascular disease patients without pacemaker executed a maximal cardiopulmonary exercise test on bike (peak respiratory gas exchange ratio >1.09), to assess peak heart rate (HRpeak), oxygen uptake (VO2peak) and cycling power output (Wpeak). The first and second ventilatory threshold (VT1 and VT2, respectively) was determined and extrapolated to %VO2peak, %HRpeak, %heart rate reserve (%HRR) and %Wpeak for comparison with guideline-based exercise intensity domains. RESULTS: VT1 was noted at 62 ± 10% VO2peak, 75 ± 10% HRpeak, 42 ± 14% HRR and 47 ± 11% Wpeak, corresponding to the high intensity exercise domain (for %VO2peak and %HRpeak) or low intensity exercise domain (for %Wpeak and %HRR). VT2 was noted at 84 ± 9% VO2peak, 88 ± 8% HRpeak, 74 ± 15% HRR and 76 ± 11% Wpeak, corresponding to the high intensity exercise domain (for %HRR and %Wpeak) or very hard exercise domain (for %HRpeak and %VO2peak). At best (when using %Wpeak) in only 63% and 72% of all patients VT1 and VT2, respectively, corresponded to the same guideline-based exercise intensity domain, but this dropped to about 48% and 52% at worst (when using %HRR and %HRpeak, respectively). In particular, the patient's VO2peak related to differently elicited guideline-based exercise intensity domains (P < 0.05). CONCLUSION: The guideline-based exercise intensity domains for cardiovascular disease patients seem inconsistent, thus reiterating the need for adjustment.

Microvascular reactivity in rehabilitating cardiac patients based on measurements of retinal blood vessel diameters.

BACKGROUND: Exercise-based rehabilitation improves general cardiovascular fitness. The impact on the microvascular system has been studied in less detail. We measured changes in retinal blood vessel diameters, as a proxy for microvascular reactivity, in cardiac patients and we assessed the impact of a rehabilitation program on retinal vessel diameters. DESIGN: Cardiac patients (n = 78) and age-matched healthy controls (n = 32) performed an initial maximal endurance cycling test. Patients then participated in a 12-week rehabilitation program with additional endurance tests being performed six and twelve weeks after the initial test. METHODS: Fundus images were collected immediately before and 0, 5, 10, 15 and 30 min after the endurance test. Widths of retinal blood vessels, represented as Central Retinal Arteriolar/Venular Equivalent (CRAE/CRVE) were calculated from the images. RESULTS: At the start of the rehabilitation program, CRAE and CRVE values of the patients changed immediately after the endurance test with respectively -1.90 µm (95% CI: -3.58; -0.22) and -5.32 µm (95% CI: -7.33; -3.30) compared to baseline values. In contrast, CRAE and CRVE values of healthy controls were respectively increased [3.52 µm (95% CI: 2.34; 4.69)] and decreased [-3.17 µm (95% CI: -5.27; -1.07)]. After six and twelve weeks, CRAE responses of patients immediately after endurance test increased respectively with 5.98 µm (95% CI: 4.25; 7.71) and 4.44 µm (95% CI: 3.18; 5.71). These responses were similar to the microvascular reactions observed in the control group. CONCLUSIONS: Arteriolar and venular retinal microvascular responses in cardiac patients were different from the ones of healthy controls. Retinal microvascular response of cardiac patients improved during rehabilitation.

Increasing the medium-term clinical benefits of hospital-based cardiac rehabilitation by physical activity telemonitoring in coronary artery disease patients.

BACKGROUND: The purpose of this study was to evaluate the effect of a physical activity telemonitoring program on daily physical activity level, oxygen uptake capacity (VO(2peak)), and cardiovascular risk profile in coronary artery disease (CAD) patients who completed phase II cardiac rehabilitation (CR). METHODS: Eighty CAD patients who completed phase II CR were randomly assigned to an additional telemonitoring intervention or standard CR. The patients in the intervention group (n = 40) wore a motion sensor continuously for 18 weeks. Each week these patients received a step count goal, with the aim to gradually increase the patients' physical activity level. In the control group (n = 40), the patients wore an unreadable motion sensor for seven days for measurement purposes only (at start of follow-up, and after six and 18 weeks). At start of follow-up and after 18 weeks blood lipid profile, glycemic control, waist circumference and body mass index was assessed. VO(2peak) was assessed at start of follow-up, and after six and 18 weeks. Re-hospitalisation rate was followed during this timeframe. RESULTS: In the intervention group, VO(2peak) increased significantly during follow-up (P = 0.001), in the control group it did not (P = 0.273). A significant correlation was found between daily aerobic step count and improvement in VO(2peak) (P = 0.030, r = 0.47). Kaplan-Meier curve analysis showed a trend towards fewer re-hospitalisations for patients in the telemonitoring group (P = 0.09). CONCLUSIONS: The study showed that, to maintain exercise tolerance and lower re-hospitalisation rate after hospital-based CR in CAD patients, a physical activity telemonitoring program might be an effective intervention.

Clinical benefits of the addition of lower extremity low-intensity resistance muscle training to early aerobic endurance training intervention in patients with coronary artery disease: a randomized controlled trial.

OBJECTIVE: Muscle resistance training is often combined with aerobic endurance training during rehabilitation of patients with coronary artery disease. However, the clinical effects of additional lower-extremity low-intensity muscle resistance training during early rehabilitation (within the first month after coronary revascularization) in patients with coronary artery disease remain unclear. DESIGN: Prospective randomized controlled trial. SUBJECTS: Sixty patients with coronary artery disease. METHODS: Subjects were randomly assigned to early aerobic endurance training (n = 30) or combined aerobic endurance and resistance muscle training (n = 30). Subjects performed 18 (standard deviation 2) exercise sessions (at 65% VO(2peak), for 40 mins/session). In resistance muscle training, additional low-intensity (12-20 repetition maximum) resistance muscle exercises were performed. The following parameters were evaluated: exercise capacity, body composition, blood lipid profile, glycaemic control, blood endothelial progenitor cell and cytokine content, and muscle performance. RESULTS: A total of 47 patients with coronary artery disease completed the intervention. Total body lean tissue mass tended to increase with greater magnitude (p = 0.07), and blood high-density lipid cholesterol content increased with significantly greater magnitude in resistance muscle training (p < 0.05), compared with aerobic endurance training. Maximal exercise capacity, ventilatory threshold, and muscle performance increased, and steady-state exercise respiratory exchange ratio, and adipose tissue mass reduced significantly (p < 0.05), without differences between groups (p < 0.05). CONCLUSION: In early aerobic endurance training intervention in patients with coronary artery disease, additional low-intensity resistance muscle training contributes to a greater increase in blood high-density lipid cholesterol content, and tends to affect lean tissue mass.