A new study from the US found that patients with peripheral arterial disease (PAD), which is sometimes accompanied by pain in leg muscles, improved their walking endurance and quality of life by taking part in a treadmill walking exercise that also helped patients who did not have the classic symptoms of pain in the legs.

The study was the work of Dr Mary M McDermott, of the Northwestern University Feinberg School of Medicine in Chicago, and colleagues, and is published in the 14 January issue of the Journal of the American Medical Association, JAMA.

PAD in the lower extremities is where the arteries that delivery blood to the legs are partially or completely blocked because of plaque build-up. The condition affects about 1 in 16 adults aged 40 and over in the US. People with PAD are less able to do everyday things and decline more rapidly than the general population, said the authors in their background information.

For some patients, PAD occurs with intermittent claudication (pain in the leg muscles that comes and goes), but according to the authors it is usually the patients without these symptoms that have greater functional impairment and decline.

McDermott and colleagues wanted to find out if it was possible for PAD patients with and without leg pain to improve functional performance and other factors, by undergoing supervised treadmill exercise and lower extremity-resistance training.

For the randomized controlled clinical trial, which took place from 2004 to 2008, the researchers recruited 156 patients with PAD and randomly assigned them to a supervised treadmill exercise group, a lower extremity resistance (strength) training group, or a control group, for six months.

Before and after the trial the patients underwent physical performance assessments and filled in questionnaires. They also had their blood flow measured, which involved stopping exercise and medications and fasting for 12 hours beforehand. The examiners did not know which group the patients they examined were in.

The primary outcome measures were two physical performance tests: one was a 6-minute walk up and down a corridor, and the other was a short battery of physical performance tests to measure leg strength and balance.

The results showed that after six months:

  • In the 6-minute walking performance test, the treadmill group increased their walking distance by an average of 69 feet (20.9 m), whereas the control group’s walking distance went down by an average of 49 feet (15.0 m), for a mean difference of 118 feet (35.9 m) between the two groups.

  • The lower extremity resistance training group did not show a change in their 6-minute walking performance compared to the control group.

  • There were no differences in change in scores on the short physical performance battery test between the treadmill exercise and control groups, or between the lower extremity resistance training and control groups.

  • Participants in the treadmill exercise group had better improvements in brachial arterial flow-mediated dilation compared to the control group, but the changes in this measure for the lower extremity resistance training group were no different than those of the control group.

  • Both exercise groups showed significantly greater increases in average maximum treadmill walking than the control group.

  • The treadmill exercise group showed significantly bigger average improvement in their physical functioning score (using the Medical Outcomes Study Short-Form 36 or SF-36) and their walking impairment distance compared with the control group.

  • The lower extremity resistance training group also showed a bigger average improvement in these two scores, and also in stair climbing tests, compared to the control group.

The authors concluded that:

“Supervised treadmill training improved 6-minute walk performance, treadmill walking performance, brachial artery flow-mediated dilation, and quality of life but did not improve the short physical performance battery scores of PAD participants with and without intermittent claudication [leg pain].”

“Lower extremity resistance training improved functional performance measured by treadmill walking, quality of life, and stair climbing ability,” they added, suggesting that:

“Based on findings reported in this trial, physicians should recommend supervised treadmill exercise programs for PAD patients, regardless of whether they have classic symptoms of intermittent claudication.”

“Treadmill Exercise and Resistance Training in Patients With Peripheral Arterial Disease With and Without Intermittent Claudication: A Randomized Controlled Trial.”
Mary M. McDermott; Philip Ades; Jack M. Guralnik; Alan Dyer; Luigi Ferrucci; Kiang Liu; Miriam Nelson; Donald Lloyd-Jones; Linda Van Horn; Daniel Garside; Melina Kibbe; Kathryn Domanchuk; James H. Stein; Yihua Liao; Huimin Tao; David Green; William H. Pearce; Joseph R. Schneider; David McPherson; Susan T. Laing; Walter J. McCarthy; Adhir Shroff; Michael H. Criqui.
JAMA Vol. 301 No. 2, pp 165-174, January 14, 2009

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Sources: Journal article, JAMA press release.

Written by: Catharine Paddock, PhD