The Effects of Individualized Physical Rehabilitation Program
Abstract
Objective: to evaluate the effects of long-term aerobic training, designed with individualized method based on lactate threshold definition, on exercise capacity, HF severity and ergoreflex activity.
Methods: We evaluated 73 HF patients, mean age 53+/-1.8, 59 men, with NYHA class III, LVEF 40,8+/-0,3%. CPET performed on a treadmill ("Oxycon Pro" (Jaeger, Germany)) at baseline, in every 8 weeks and after 6 months. The cubital venous catheter was inserted before CPET. Blood samples were taken at baseline and at 1-minute intervals during test. Lactate concentration in blood was measured using analyzer i-STAT, cartridge CG4 (Abbot, USA). All patients were randomized into following groups: 50 patients of study group (SG), who underwent physical rehabilitation program (PRP), calculated due to lactate threshold; and 23 HF patients control group (CG), who underwent physical training, calculated based on VO2 percentage.
Results: At baseline CPET results in both groups did not significantly differ. VО2 at lactate threshold and VО2peak were 8.7+/-0,5; 13,5+/-0,9 ml/min/kg and 8.9 +/- 0.9; 13,6+/-1,2 ml/min/kg in study group and control group, respectively (p1=0,08, p2=0,07, respectively). After 24 weeks of training VО2LT and VО2peak were better in the study group than in control group: the increase was 16% and 24% in the main group, and 4% and 7% in the control group, respectively (p1<0,01, p2<0,01). The ergoreflex activity at baseline did not significantly differ in two study groups. After long-term aerobic training we recorded a more marked reduction in the ergoreflex activity in study group: for DBP it was 35% and 20%, VE - 48% and 25%, VE/VCO2 - 39% and 12%, in the study group and control groups, respectively. By the 24th week of training in 34 (85%) patients of the study group the severity of HF was reduced to NYHA class II, and among the patients in the control group such dynamics was observed only in 17(50%) patients.
Conclusions: aerobic exercise, designed with individualized method based on lactate threshold definition, increase exercise tolerance, reduces HF severity and ergoreflex activity more than aerobic training, calculated based on VO2peak percentage
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Introduction
Chronic heart failure (HF) is a pathological condition, which prevalence increasing every year [1, 2]. The main HF symptoms are shortness of breath, weakness and fatigue during physical activity [3]. Traditionally, patients with HF have been instructed not to exercise in order to avoid deterioration. More recently, physical rest advised in acute HF or destabilisation of chronic HF. In stable condition patient should be encouraged to carry out daily physical activities that do not induce symptoms [4], in order to prevent muscle deconditioning.
The one of key problems of HF rehabilitation is to define exercise mode and intensity that are safe and effective [5]. Exercise intensity usually categorized using the percent of maxHR or VO2 max percentage.
In previous work [6] we have proposed a new method of compensatory-adaptive four exercise stages definition during CPET: lactate threshold (LT), pH-threshold (pH-T), respiratory compensation point (RCP) and aerobic limit. Lactate threshold determined when blood lactate level began to increase. pH-threshold determined when blood pH level began to decrease. Respiratory compensation point (RCP) determined when ventilation dramatically increases relative to carbon dioxide output (VE/VCO2). By continuous increase of work rate, oxygen consumption, up to a certain point, increases linearly and become stable - it is aerobic limit. We have already reported significant diagnostic and prognostic value of determination of lactate and pH thresholds in patients with chronic heart failure [7]. We proposed to define a exercise training intensity for HF patients with III NYHA class due to lactate threshold.
Conclusion
Aerobic exercise, designed with individualized method based on lactate threshold definition, increase exercise tolerance, reduces HF severity and ergoreflex activity more than aerobic training, calculated based on VO2peak percentage.