Comparison of treadmill exercise testing protocols for wheelchair users

Summary

The reduced early mortality and the increased life span of persons with spinal cord injury (SCI) and other chronically disabling conditions which result in loss of use of the legs places them at increased risk of coronary heart disease, diabetes, and hypertension. Exercise testing in this population is becoming more common, but there is a need for assessment of protocols in order to determine the best method to elicita maximal response in a reasonable time without endangering the patient. Three wheelchair treadmill protocols were compared in seven men with paraplegia aged 21–44 years (five SCI, two post-polio). Subjects repeated each protocol to estimate reliability. Protocol G consisted of increasing treadmill grade at a constant speed (4.8 km·h⁻¹); in protocol S, the speed was increased at a constant grade (0%), and in protocol C, speed and grade were increased. Two-minute stages were used in all protocols. Peak oxygen uptake [$\dot V$O_2max; mean (SD): 23.6 (5.8) ml·kg⁻¹·min⁻¹; 1.66 (0.37) l·min⁻¹], $\dot V$CO₂ production [1.98 (0.46) l·min⁻¹], ventilation volume [83.0 (25.6) l·min⁻¹], respiratory exchange ratio [1.2 (0.12)], and heart rate [173 (18)] were determined. Over all trials none of the variables was significantly different among the three protocols, but all were highest in C and lowest in S. Reliability coefficients for absolute and relative $\dot V$O_2max ranged from 0.76 and 0.81 in G to 0.95 and 0.98 in C (all P<0.05). These data suggest that an incremental treadmill test similar to the C protocol may be the optimal method to use when evaluating the exercise capacity of wheelchair users.