A cross-sectional prospective design was used to compare the effectiveness of the shuttle walking test (SWT) and the maximal cycle ergometry test (CET) to assess the functional capacity of patients with chronic hypercapnic respiratory failure due to severe kyphoscoliosis. Twenty-four patients completed both the SWT and CET. Heart rate, blood pressure, leg fatigue, chest pain and dyspnea (Borg's scale) were measured immediately after each test. Correlation coefficients and Bland-Altman analysis were used to compare the two methods. Borg's dyspnea, leg and chest pain after exercise were not significantly different between tests. Only heart rate (SWT 130[20.7] versus CET 116[28.75]; p = 0.048) and diastolic blood pressure (SWT: 85.5[13.75] versus CET 95[17.5]; p = 0.021) were slightly but significantly different between the two protocols. There was a good positive correlation between the distance walked in SWT and maximal oxygen consumption (r = 0.675; p < 0.001). SWT and CET testing elicited similar clinical and hemodynamic responses. SWT is a feasible measure of functional capacity in this patient group.