The Relationship between a Progressive versus Single-stage Treadmill Test for Evaluation of Claudication

INTRODUCTION Peripheral arterial disease (PAD) is defined by atherosclerotic plaque buildup and subsequent blockages along the arterial walls of the extremities[1]. The narrowing of the arteries leads to reduced blood flow to the leg musculature upon exertion clinically resulting in complaints of leg pain. This pain, known as claudication, stops once muscular exertion ceases and metabolic demand returns to baseline[2]. Prior to 1991, the most common means to evaluate claudication was a single-stage treadmill walking test. The single-stage treadmill walking test consists of a fixed speed, fixed slope protocol. In 1991, Gardner et al.[1] reported results from a progressive treadmill walking test which consisted of a fixed speed with a progressively increasing slope protocol. The progressive test reduced testing time likely due to increased muscular demand. Due to the discrepant nature of the protocols, there has been no previous attempt to determine a relationship between these protocols. This has led to an inability to compare historical data to more recent data and allow for comparisons among different laboratories as the two protocols continue to be used. Therefore, the purpose of this study was to determine a relationship between the two protocols to allow for increased comparison of results among laboratories and studies. To allow for commonality, it was hypothesized that metabolic work demands of leg muscles are the primary cause of ischemic pain. Thus, a relationship in the mechanical work demands should similarly exist and thus allow for approximation of performance in one walking test based on the other.