Walking at high intensity improved leg function among people with peripheral artery disease (PAD), according to research published in the Journal of the American Heart Association

“We were surprised by the results because walking for exercise at a pace that induces pain in the legs among people with PAD has been thought to be damaging to leg muscles,” said senior study author Mary M. McDermott, MD, the Jeremiah Stamler Professor of Medicine in the division of general internal medicine and geriatric medicine and of preventive medicine at Northwestern University’s Feinberg School of Medicine in Chicago. “Based on these results, clinicians should advise patients who have had PAD to walk for exercise at a pace that induces leg discomfort, instead of at a comfortable pace without pain.”

In an accompanying video, Dr McDermott acknowledged that walking with more intensity may be uncomfortable for patients with PAD. To encourage patients, she noted, they can work with a coach, ask their clinician for a referral for supervised exercise, or choose to walk with a partner.


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Courtesy of the American Heart Association.

“We had a coach that telephoned the participants weekly and helped encourage the participants to keep going . . . at that faster, more uncomfortable pace,” Dr McDermott said. “If a patient is just able to stick with it, most people will report that they get significant improvement in their ability to walk without leg discomfort.”

Study Rationale and Design

Previous research found that walking for exercise, particularly on a treadmill while supervised by a staff member, improves walking ability and walking distance among people with PAD. However, because this condition causes cramping, pain, and other ischemic leg symptoms while walking, the researchers set out to investigate what effects pushing through that pain compared with walking at a comfortable pace without leg discomfort would have on speed, strength, and balance.

This post hoc analysis examined the effects of home-based walking among 264 people (average age, 69 years; 48% women; 61% Black adults) with PAD participating in the randomized clinical trial Low-Intensity Exercise Intervention in PAD (LITE). The study was conducted from September 2015 to October 2020 at 4 US medical centers (Northwestern University, Tulane University, University of Minnesota, and University of Pittsburgh) and included 305 people overall.

Participants were randomly assigned to 1 of the following 3 groups for 12 months:

  • The low-intensity group (38%) walked at home at a comfortable pace 5 days a week
  • The high-intensity group (41%) walked at home at a pace that induced leg symptoms 5 days a week
  • Nonexercisers (21%) did not walk for exercise

Both walking exercise groups wore an ActiGraph to monitor exercise frequency, intensity, and duration. Personalized thresholds for the ActiGraph intensity were defined for each participant and corresponded to a pace that induced leg symptoms (high intensity) and a pace without leg symptoms (low intensity). Participants were asked to work up to 50 minutes of walking per session. A coach met with participants in person weekly for 4 weeks and then via telephone for the rest of the study, which lasted for 12 months.

Participants completed tests of leg function at baseline, 6 months, and 12 months during the study. These included walking speed over a 4-meter distance (13 feet) at usual pace and fastest pace and the Short Physical Performance Battery (SPPB).

Key Findings

The study outcomes included:

  • Walking speed: The high-intensity group walked 11 feet per minute faster at 6 months and more than 16 feet per minute faster at 12 months than the low-intensity group. Compared with nonexercisers, the high-intensity group walked nearly 13 feet per minute faster at 6 months; however, this increase was not statistically significant at 12 months. The low-intensity group showed no improvement in walking speed at 6 months or 12 months compared with nonexercisers.
  • Leg function: At 12 months, the high-intensity group scored almost 1 point higher on the sum of the 3 leg function tests in the SPPB compared with the low-intensity group. Compared with no exercise, high-intensity walking had no significant effect on SPPB scores at 6-month or 12-month follow‐up.

Although participants who walked at a comfortable pace clocked in more minutes of walking, this low-intensity intervention did not improve walking velocity or SPPB scores at either 6- or 12-month follow-up.

The findings suggest “no pain, no gain” for walking exercise in PAD, Dr McDermott said. “Exercise that induces leg pain is beneficial, though difficult. We now are working to identify interventions that can make the higher intensity exercise easier — and still beneficial — for people with PAD.” She noted that improvements in walking ability typically begin after 4 to 6 weeks of walking at a pace that induces leg discomfort.

Study limitations included the home setting; the results may not apply to supervised exercise programs, which are the standard of care and first-line therapy recommended in the American Heart Association/American College of Cardiology clinical practice guideline. However, this trial demonstrated that walking exercise in or around the home can be beneficial for people with PAD. Another limitation is that the results were not prespecified outcomes for this clinical trial. Future research is needed to confirm the findings, the study authors noted.  

Some study author(s) declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.

References

Hammond MM, Spring B, Rejeski WJ, et al. Effects of walking exercise at a pace with versus without ischemic leg symptoms on functional performance measures in people with lower extremity peripheral artery disease: the LITE randomized clinical trial. J Am Heart Assoc. 2022;Jul 27:e025063. doi:10.1161/JAHA.121.025063

“No pain, no gain” approach improves walking ability with peripheral artery disease. News release. American Heart Association. July 27, 2022. Accessed July 27, 2022. https://newsroom.heart.org/news/no-pain-no-gain-approach-improves-walking-ability-with-peripheral-artery-disease