HOME-BASED VS SUPERVISED EXERCISE FOR CLAUDICANTS (NIH)

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Peripheral arterial disease (PAD) is a leading cause of morbidity due to ambulatory limitations associated with intermittent claudication.1-4 Intermittent claudication is ischemic muscular pain that occurs in the calf, thigh, or buttock muscle groups during ambulation when the pace exceeds the capacity of the peripheral circulation to adequately perfuse the active lower extremity musculature. Intermittent claudication afflicts 5% of the US population older than 55 years of age, 5 thereby limiting daily physical activities6 and negatively affecting quality of life7 in many older adults. Because ambulation is one of the primary physical activities performed by the elderly, 8 it is not surprising that PAD subjects adopt a sedentary lifestyle and typically cluster around the extreme low end of the physical activity spectrum.9 The ambulatory dysfunction and sedentary lifestyle in subjects with PAD may trigger a decline in other domains of physical function. For example, PAD subjects have reduced strength in the lower extremities, 10 impaired balance and higher prevalence of falling, 11 altered gait even before claudication pain occurs, 12 worse self-perceived ambulatory function, 13 and lower health-related quality of life14 than non-PAD controls. Consequently, PAD subjects have difficulty completing activities of daily living that utilize the lower extremities, 13 while some subjects are unable to perform these tasks altogether. A primary therapeutic goal for PAD patients with intermittent claudication is to regain lost physical function through exercise rehabilitation.15 Medically supervised exercise programs have been studied extensively over the past 35 years, and are efficacious in the clinical management of intermittent claudication.16 Specifically, supervised exercise rehabilitation improves initial claudication distance (ICD - the distance walked to the onset of claudication pain) and absolute claudication distance (ACD - the distance walked to maximal claudication pain) during a standardized treadmill test, as well as overground ambulatory function, perceived ambulatory function, physical activity level, quality of life, and calf blood flow in PAD patients with intermittent claudication.16-24 Consequently, exercise-mediated improvement in claudication pain is a triggering event that breaks the downward spiraling chain of events in physical function in PAD patients. Supervised exercise is the standard method to rehabilitate PAD patients with intermittent claudication, and is efficacious in improving claudication distances measured during standardized treadmill protocols, 16 as well as general ambulatory function and quality of life.18, 22 Unfortunately, only a small percentage of eligible patients can feasibly attend supervised programs on a regular basis, thereby limiting the generalizability of the research findings. The vast majority of PAD patients could, however, benefit from an exercise program transported to the community setting (i.e., home-based walking). However, few studies have been published on home exercise programs for PAD patients with intermittent claudication, none have used a randomized, controlled trial design, most have suffered from small sample sizes, and most have narrowly focused on PAD-specific outcomes such as claudication distances during a treadmill test without considering the impact of the exercise program on more general measures of physical function and overall health-related quality of life.23,25,26 In addition to these problems, the inability to accurately quantify the volume of exercise performed in home-based programs is the most serious limitation, rendering previously reported data as difficult to interpret. Recent technology using a step activity monitor can accurately record the number of steps taken in the community setting on a minute-to-minute basis for up to a month, as well as record the daily amount of time spent walking and the intensity and duration at which the walking occurred (i.e., cadence).27 We propose to conduct a prospective, randomized controlled clinical trial designed to address the limitations of previous home-based exercise programs, thereby allowing us to directly compare the effects of home-based and supervised programs to improve the functional status of PAD patients limited by intermittent claudication. The results from this randomized controlled clinical trial has the potential to make a significant impact in the clinical management of PAD patients with intermittent claudication because the results will be generalizable to the vast majority of patients who do not have access to a supervised exercise program, but who can benefit from a home-based walking program with minimal intervention from clinicians and minimal use of resources.A.2. Specific Aims and Hypotheses Specific Aim #1. This prospective, randomized controlled clinical trial will compare the changes in ambulatory function, vascular function, and health-related quality of life in PAD patients limited by intermittent claudication following a home-based exercise rehabilitation program, a supervised exercise program, and an attention-control group who perform light resistance training exercise. A comparison between the home-based exercise program and the supervised exercise program will be done using a bio-equivalent analytic approach. Hypothesis #1a. A home-based exercise program utilizing new physical activity monitoring technology that can accurately quantify exercise adherence as well as the intensity, duration, and volume of exercise sessions will result in similar changes in ambulatory function, vascular function, and health-related quality of life compared to a standard, supervised exercise program. Hypothesis #1b. Both the home-based and supervised exercise rehabilitation programs will result in greater changes in ambulatory function, vascular function, and health-related quality of life than an attention-control group who perform light resistance training exercise. Specific Aim #2. To determine whether changes in walking economy, calf muscle circulation, and calf muscle oxygenation are the major physiologic mechanisms by which both home-based and supervised exercise rehabilitation improve ambulatory function. Hypothesis #2. The change in walking economy, calf muscle circulation, and calf muscle oxygenation will each be predictive of improved ambulation following the home-based exercise program as well as the supervised exercise program.