Reliability of constant-load treadmill testing in patients with intermittent claudication

Area of Science:

• Cardiovascular Medicine
• Rehabilitation Science
• Exercise Physiology

Background:

• Constant-load treadmill testing is a common method for evaluating walking ability in peripheral arterial disease (PAD) patients.
• Reproducibility concerns have previously cast doubt on the reliability of this testing method.
• Assessing functional capacity changes is crucial for monitoring disease progression and treatment efficacy in PAD.

Purpose of the Study:

• To investigate the reliability of constant-load treadmill testing.
• To specifically assess treadmill testing at a speed of 3 km/h and a constant inclination of 12%.
• To determine the reproducibility of initial claudication distance (ICD) and maximum walking distance (MWD).

Main Methods:

• Sixty-eight patients with stable peripheral arterial disease participated.
• Participants underwent two treadmill testing sessions (3 km/h, 12% inclination) within three weeks.
• Measurements included initial claudication distance (ICD), maximum walking distance (MWD), and self-reported walking distances.

Main Results:

• High correlation coefficients (0.8) and low within-subject variation (15% for ICD, 13% for MWD) indicate low variability.
• Good reproducibility was confirmed by intra-class correlation coefficients (0.78 for ICD, 0.83 for MWD).
• No significant learning effects were observed between test sessions.
• Correlation between treadmill-measured and self-reported walking distances was poor.

Conclusions:

• Constant-load treadmill testing at 3 km/h and 12% inclination is a reproducible method for stable PAD patients familiar with the test.
• The test reliably assesses walking capacity under specific treadmill conditions.
• Treadmill walking distances should not be used to infer a patient's actual walking range on level ground.