Exertional Dyspnea Comparison in Four Maximal Training Exercises used in Pulmonary Rehabilitation: Continuous versus Bi-Level Responses in Time

Objective: a) To compare the exertional Dyspnea (ED) values at the maximum levels of four tests used in pulmonary rehabilitation, performed by ED subjects; b) to analyze the ED evolution in time during two training exercises: Constant, the CE 80% and Bi-level, the Square wave endurance exercise test (Sweet). Design: Twenty-four non-medicated ED subjects, aged 33 to 60 years gave their informed consent. They performed, before any intervention, 4-maximal exercises (at 24 hrs interval): incremental (30W/3min), to determine ventilatory anaerobic threshold (VAT) and peak work rate (PWR); constant CE 80%; Bi-level (SWEET-45 min alternating 4min-VAT and 1minPWR): and the 6 min walking test (6MWT). ED was measured (Borg scale) at PWR; 14th-15th, 29th-30th, 44th-45th SWEET min, and 1st, 3rd, 5th, 10th and maximal minute in CE 80%. Results: In the CE 80% nobody could maintain the 45 min while the SWEET was sustain 45 minutes by all subjects. The random effects model was used for ED evolution. The essential facts are: On CE 80%, ED is largely higher (p<0.001) and increased progressively until the go up. The ED variances per unit time on SWEET-Base, were not different, however it decreased at the SWEET-Peak (p<0.001). Conclusions: 1) The Sweet-base is the lowest dyspnea level between the four maximal exercise-tests studied; 2) The Sweetpeak's ED represents 69% of CE 80% and 67% of PWR ED; 3) The 6MWT's ED is 95% of Sweet-peak's ED and both represent respectively 65% and 69% of the PWR ED; 4) The CE 80% appears to be an exercise with exceedingly dyspnea as ED tends to increase progressively, while on the contrary, the Sweet-peak allows a significant decrease in ED per unit time (p<0.001).