Comparison of oxygen uptake during a conventional treadmill test and the shuttle walking test in chronic airflow limitation.
The purpose of this study was to investigate the relationship between performance on the shuttle walking test and maximal oxygen uptake (VO2max) during a conventional treadmill test in patients with chronic airflow limitation. Two different techniques were used to measure oxygen consumption, i.e. conventional Douglas bag techniques (treadmill test) and a portable oxygen consumption meter (shuttle test). Initially, 19 patients performed a shuttle walking test (after one practice walk) and a maximal treadmill walking test, in a randomized, balanced design. Subsequently, 10 patients, (after one practice) completed an unencumbered shuttle walking test and one supporting the portable oxygen consumption meter, in random order. The results of the first experiment revealed a strong relationship between performance during the shuttle walking test and VO2max during the treadmill walking test (r = 0.88). The results of the second experiment consistently demonstrated an incremental increase in oxygen consumption and ventilation in response to the increasing intensity of the shuttle walking test. Again, a strong relationship between VO2max and performance on the shuttle test was demonstrated (r = 0.81). We concluded that the shuttle walking test is a valid field exercise test of functional capacity. Performance on the test relates strongly to VO2max, the traditional indicator of cardiorespiratory capacity.