Treadmill testing (TT) is the standard method to evaluate patients with intermittent claudication (IC), but cycling test (CT) has been demonstrated as an alternative to minimise the impact of body mass and altered gait on exercise performance. To investigate the differences in cardiopulmonary responses and tissue saturation of calf measured by near-infrared spectroscopy (NIRS) between TT and CT, we evaluated 9 men with IC. For TT was used with a fixed speed of 3.2 km/h and 0% grade for 5 min with increases of 3.5% every 3 min, as described by Hiatt (1988). CT was performed as described by Askew (2002), pedalling at 20W for 5 min and 20W increases every 3 min. Patients underwent both tests, with an interval between 3 and 14 days. Gas exchange was assessed by a breath-by-breath system (CPX Ultima, Medgraphics). Tissue saturation was evaluated by a portable wireless system of NIRS (Portamon, Artinis) attached to the calf. As a physiological calibration of NIRS, an arterial occlusion manoeuvre (AO) was done before each test maintaining a cuff inflated on the thigh, at a minimum of 250 mmHg for 5 min. To examine the normal distribution of data, Shapiro-Wilk test was done. Data comparisons were done by using paired t-tests. Significance level was previously set at p < 0.05. No significant differences were found for peak oxygen uptake in mL/kg.min (TT: 17 ± 4; CT: 16 ± 5; p = 0,608), peak heart rate in bpm (TT: 124 ± 17; CT: 125 ± 14; p = 0,82), peak minute ventilation in L/min (TT: 49 ± 11; CT: 53 ± 9; p = 0,466) and peak respiratory exchange ratio (TT: 1.08 ± 0.10; CT: 1.17 ± 0.07; p = 0,055). Peak exercise saturation at calf was more reduced during TT (TT: 48.7 ± 6.3; CT: 58.0 ± 7.3; p = 0,005) and both were higher than minimum saturation obtained during AO (TT: 48.7 ± 6.3; AO: 45.3, 0 ± 6.2; p = 0,004 / CT: 58.0 ± 7.3; AO: 45.1 ± 5.3; p = 0,002). Calf demand for blood in incremental exercise is higher in treadmill than in cycle ergometer, despite similar cardiopulmonary responses.
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