Stair Descending vs. Stair Ascending Exercise

Study design: Twelve elderly males with chronic heart failure, New York Heart Association class I-II, will participate in this study. Participants will be allocated into two equally-sized groups: a stair descending group (n = 6) and a stair ascending group (n = 6). At the beginning of the study, the volunteers will perform an acute bout of stair descending or stair ascending exercise on an automatic escalator (4 sets of 3 min each, speed will be set at 45 steps∙min-1). Step height will be 20.5 mm. Before and at day 2 post exercise, physiologic measurements will be performed and blood samples will be collected. Then, participants will carry out six weeks of stair descending or ascending training consisting of three exercise sessions per week (the first two weeks the speed will be set at 45 steps∙min-1, the next two weeks at 50 steps∙min-1 and the last two weeks at 55 steps∙min-1 for both groups). Afterward, they will repeat the acute stair descending or ascending protocol, as carried out at the beginning of the study, and the same physiologic measurements will be performed and blood samples will be collected. Measurements: Isometric (at 90 knee flexion), concentric and eccentric peak torque at 60o∙s-1of quadriceps femoris, pain-free range of motion, delayed onset muscle soreness and creatine kinase will be measured.