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EFFORT PERCEPTION AND HEMODYNAMIC RESPONSES TO THE 3/7 VS. 3X9 METHODS IN HEART FAILURE AND IN CORONARY ARTERY DISEASE PATIENTS: A RANDOMIZED-CROSS-OVER STUDY

Objective: Patient adherence to cardiac rehabilitation (CR) centers may be improved by shorter exercise time. The new ‘3/7-method’, which consists of 5 successive sets of exercise with an increasing number of repetitions (3 to 7) separated by brief inter-set rest intervals (15 s), has been proven to achieve a greater and faster strength gain in healthy subjects. Further characterization (i.e., Borg scale, blood pressure (BP) and heart rate (HR)) of the 3/7-method safety is needed before using it in CR in patients with reduced ejection fraction (HFrEF) and coronary artery disease (CAD). Design and method: Using a randomized and cross-over study design, we compared the variation of Borg scale, BP and HR in the ‘3/7-method’ vs ‘3X9 method’ (gold standard - .3 to 9 repetitions with a longer inter-set rest interval (1 min)) in 23 HFrEF (58 ± 9y-13% female) and 22 CAD patients (64 ± 10y-14% female). The strength training consisted in leg extension against a load of ~ 70% of 1 repetition maximal. Perceived exertion was assessed at the end of the last set by using the modified Borg Scale (0–10). HR and BP were assessed noninvasively beat by beat. Results: Baseline BP, HR and Borg scale at the end of exercise were similar within the two methods. HR was higher with the 3/7 method compared to the 3X9 method in the HFrEF (85 ± 11 vs. 83 ± 12 bpm,-p = 0.014) and CAD (90 ± 13 vs. 87 ± 14 bpm,-p = 0.03) patients. In the CAD patients, systolic BP increased more with the 3/7 method compared to the 3X9 method (143 ± 22 vs. 133 ± 20 mm Hg-(p < 0.001)). Conclusions: The 3/7 and 3X9 strength training protocols elicit similar effort perception in our patients. The 3/7 method increases slightly HR in both groups and induces minimal rise in systolic BP in CAD patients. Taken together, our study suggests that, compared to the 3x9 method, the new 3/7-method is well tolerated and time-saving, at the price of small and likely irrelevant HR and BP variations. These encouraging results warrants further investigation of the advantages (i.e, adherence, improve strength and exercise capacity) of the 3/7 method in CR.