EFFECTS OF EXERCISE TRAINING AND ACTIVITY RESTRICTION ON 6-MINUTE WALKING TEST-PERFORMANCE IN PATIENTS WITH CHRONIC HEART-FAILURE

Eighteen hospitalized patients with severe chronic heart failure (ejec tion fraction [mean +/- SEM] 21% +/- 1%) underwent 3 weeks of exercise training (interval bicycle ergometer and treadmill walking training e xercises) and 3 weeks of activity restriction in a random-order crosso ver trial. Before and after exercise training and after activity restr iction, a B-minute walking test was performed to determine the maximum distance walked, hemodynamic and cardiopulmonary responses, norepinep hrine levels, and ratings of leg fatigue and dyspnea while walking. A ramp test on bicycle ergometer (increments of 12.5 W/min) was performe d before and after exercise training and activity restriction to deter mine peak oxygen uptake. After training, the maximum distance walked w as increased by 65% (from 232 +/- 21 m at baseline to 382 +/- 20 m; p < 0.001), whereas after activity restriction (253 +/- 19 m) there was no significant difference compared with baseline. No significant diffe rences in hemodynamic and cardiopulmonary parameters (with the excepti on of the ventilatory equivalent for carbon dioxide and perceived exer tion) or norepinephrine levels were observed during walking tests. Imp rovement in maximum distance walked correlated significantly with trai ning-induced increase in peak oxygen uptake measured during bicycle er gometry (r = 0.47, p < 0.05). The lower the maximum distance walked at baseline, the more pronounced the training-induced prolongation of ma ximum distance (r = -0.73; p < 0.001). These data support the value of exercise training in patients with severe chronic heart failure for i mproving maximum distance walked, as documented by the 6-minute walkin g test. The impairment of walking test performance during activity res triction suggests a need for long-term exercise training programs.