Greater walking distance during acute intermittent, compared to the same ground speed, endurance shuttle protocol in COPD: an interim analysis

Background: In COPD, intermittent cycling is associated with greater exercise endurance time and work output than continuous cycling.

Aim: To compare the distance walked between intermittent and continuous walking protocols.

Methods: On two separate visits, 11 patients with COPD (FEV1% predict: 55±15) performed two shuttle walking protocols to the limit of tolerance (Tlim): i) a continuous shuttle walk (CSW) and ii) an intermittent shuttle walk (ISW, alternating 1-min shuttles with 1-min rest periods) both sustained at a walking speed equivalent to 85% of VO2peak predicted from the Incremental Shuttle Walking Test. Cardiac output (CO, measured by cardio-impedance), arterial oxygen saturation (SpO2) and Borg symptoms were assessed.

Results: Endurance time at Tlim was greater (p<0.001) for ISW compared to CSW (23.1±12.6 versus 5.2±4.3 min). At Tlim walking distance was significantly greater for ISW compared to CSW (Table 1). At iso-distance (i.e: when walking distance was the same between CSW and ISW), CO, dyspnoea and leg discomfort were lower and SpO2 greater during ISW compared to CSW (Table 1).

Conclusion: Compared to CSW, ISW is associated with reduced dyspnoea, oxygen desaturation and circulatory load, thereby facilitating a two-fold increase in walking distance.