Study Design

This was a feasibility study in which patients with lifestyle limiting claudication participated in a 12-week, home-based, RAS-enhanced, music-guided rehabilitation program.

Sample

English-speaking participants (> 18 years) with claudication due to PAD were recruited via directed mailing from 2 large metropolitan hospitals in the midwestern United States. Institutional Review Board approval was obtained at both sites. All patients provided informed consent prior to any study procedures. The presence of PAD was confirmed via a resting ankle brachial index of < 0.90 (15). Exclusion criteria were ischemic foot ulceration, exercise capacity limited because of conditions other than claudication, class III–IV heart failure, peripheral or myocardial revascularization within the previous 6 months, contraindications to exercise per American College of Sports Medicine (16), or inability to hear music.

Procedure

Participants came to the laboratory 2 times at baseline and then for follow-up at 6 and 12 weeks. During the first visit, preferred walking cadence (steps/minute) was determined by having the participant walk at their usual, preferred walking speed for 30 seconds. Participants then completed a practice 6MWT to limit any learning effect (14). The 6MWT is a valid and reliable method for evaluating walking distance in patients with claudication (17). Subjective walking ability was assessed using the Walking Impairment Questionnaire (18), Peripheral Artery Disease Quality of Life Questionnaire (PADQOL) (19), PROMIS Mobility, PROMIS Pain-interference, and PROMIS Profile 57 (20). Participants were given an accelerometer (Actigraph GTX3; Actigraph Corporation, Pensacola, FL) to wear on their hips for 7 d to determine volume of daily physical activity (21). Participants also selected types of music that they did and did not enjoy listening to.

During the second visit, a second 6MWT was completed. This 6MWT was used as the baseline measure and follow-up measure at 6 and 12 weeks. RAS was not used during the 6MWT. The Actigraph GTX3 was collected, and the intervention was explained.

Exercise Intervention

Participants were instructed to exercise at home, 3 times per week, progressively increasing the duration from 30 to 60 min over 12 weeks. The exercise program followed standard guidelines for exercise rehabilitation for claudication (2,22). Participants performed walking to a level of mild-moderate claudication pain (i.e., 2 to 3 on the 1 to 5 claudication pain scale) within 10 min, followed by resting until the claudication pain dissipated, followed by resumption of walking. Participants walked on their own in the community that they live in. We worked closely with each individual to identify places to walk in their community (e.g., mall walking, parks, Chicago trail system). Participants did not use treadmills during the study.

RAS-Enhanced Music

Participants were given an iPod loaded with playlists that consisted of RAS-enhanced music within their preferred genres. The playlist was altered using the Audacity^® software so that the tempo of the music was increased to a tempo 10 to 15 beats per min higher than the patient's usual walking cadence (steps per minute). The bass of the music was enhanced to accentuate the rhythm (i.e., RAS-enhancement). Participants were instructed on how to use the playlist and headphones and walk to the beat of the music. Each participant was provided with numbered playlists that represented an increase in exercise intensity and duration (i.e., playlists with 2% to 5% increase in tempo). Participants were notified during the biweekly phone calls when they should switch to the new playlist to progress the exercise program. Each playlist was developed to allow for a progressive increase in exercise intensity (i.e., a warm-up tempo), followed by an overload phase (i.e., an overload tempo), and a cool down phase (i.e., a cool-down tempo).

Exercise Adherence

Participants used a Fitbit tracker for assessment of adherence. Step counts were synced automatically, and data were transmitted to an associated deidentified Fitbit account. Using the Fitbit, an exercise session was documented as completed, and adherence percentages were calculated in days per week exercised divided by recommended days × 100 (4).

Statistical Analysis

Measures of central tendency were used to describe the sample. We developed a repeated-measures mixed model with unstructured covariance matrix and robust standard errors to assess within-group treatment differences over time. Pearson correlations were used to assess associations between change in walking distance and subjective measures of physical function and pain interference.

Walking Distance

At 6 weeks, total walking distance increased by 48 m (P ≤ 0.001), and functional claudication distance increased by 46 m (P = 0.13). At 12 weeks, distance increased by 41 m (P = 0.001, Table 2), and 43 m in functional claudication distance (P = 0.13).

TABLE 2. Rhythmic auditory stimulation rehabilitation.

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Daily Physical Activity

Daily physical activity expenditure, measured via actigraphy, increased from 239 to 260 Kcal·d⁻¹, and the daily actigraphy step count increased from 2,589 steps to 3,480 steps per day.

Self-Reported Outcomes

The PADQOL physical function limitation due to symptoms was improved by 11 units (P = 0.03), and the PROMIS profile physical function was improved by 3 units (P = 0.04). The PROMIS measures indicated a trend for reduction in pain interference (P = 0.09). Change in claudication onset distance was strongly correlated with exercise adherence (r = 0.87, P < 0.001), and reduced pain-interference (r = −0.61, P < 0.02).

Exercise Adherence and Satisfaction

Participants completed a mean of 32 of the 36 (89%) prescribed home exercise training bouts. They were satisfied with the intervention and with the home-based exercise program (mean 8.3 ± 1.6; Likert scale 0 to 10; 0 = not satisfied to 10 = extremely satisfied) and indicated that they enjoyed exercising to music very much (mean 8.8 ± 1.7, Likert scale 0 to 10; 1 = not at all to 10 = very much). No participants expressed a dislike of the RAS-music.

Limitations

This study was not designed to determine efficacy but to gain experience with the intervention methodology. We did not use a device to measure steps per minute. Future studies should assess regular step count using a device such as a step-watch. The use of the Fitbit for adherence determination has only been validated for use in the general population. (26,27) Since the Actigraph GTX3 devices were mailed back after the participant's last research visit, we did not ask participants about reasons for nonadherence. Participants in the study may represent those who are interested in exercise and therefore may not be representative of the general patient population. We controlled for the potential learning effect of the 6MWT, but we did not assess cadence or stride-length in this study. This feasibility study included a small sample size, limiting any determination of efficacy; moving forward there should be a randomized controlled trial to determine efficacy.