Comparison of cardiopulmonary responses during 2 incremental step tests in subjects with COPD.
BACKGROUND
It is well established that the work rate increment size affects the duration of test and physiological responses to exercise during cycling in patients with COPD. However, this has never been tested for incremental step tests.


OBJECTIVE
To compare the exercise tolerance  time, cardiopulmonary stress, and perception of effort between the Chester step test (CST) and a modified incremental step test (MIST).


METHODS
Thirty-two subjects with COPD (FEV(1) 50 ± 15% of predicted) were randomized to perform the CST and MIST on the same day, an hour  apart, on a single step (20 cm high). During tests, pulmonary gas exchange was measured continuously by a portable metabolic system.


RESULTS
CST had shorter duration and also lower number of steps, in comparison with MIST. However, similar cardiopulmonary responses were observed at exercise  peak: oxygen uptake (V(.)(O(2))) 1.22 ± 0.59 L/min vs 1.24 ± 0.55 L/min, minute ventilation (V(.)(E)) 30.8 ±  12.7 L/min vs 30.0 ± 11.7 L/min, heart rate 86 ± 13 beats/min vs 85 ± 13 beats/min, and S(pO(2)) 87 ± 7% vs 87 ± 6%. Dyspnea and leg fatigue scores when correcting for exercise duration were higher for CST.


CONCLUSIONS
The slower the work  rate increment during step test, the higher the exercise tolerance. Regardless of the work rate increment, cardiopulmonary stress and exertion effort at peak exercise were equivalent between tests.
Clinical Exercise Physiology Unit, Postgraduate Program in Rehabilitation Sciences, Nove de Julho University, São Paulo, Brazil.
Carlos Henrique Silva
CH
de Andrade
Anderson Alves
AA
de Camargo
Brenda Pitman
BP
de Castro
Carla
C
Malaguti
Simone
S
Dal Corso
D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005080:Exercise Test / Q000379:methods*; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000503:physiopathology*; D011659:Pulmonary Gas Exchange