Peripheral arterial disease of the lower limbs affects approximately 200 million adults worldwide.
Its genesis is mainly linked to an atherosclerotic disease of the arteries, with a consequent reduction in the supply of oxygen to leg muscles.
The symptoms described by the patients are highly variable. Functional impairment of varying degrees usually prevails, which reduces the ability to walk, causing pain in the lower limbs.
On the contrary, cases of ischemia that induce pain at rest or localized trophic alterations are rare.
The drugs used to treat this condition are antiplatelet, pentoxifylline, cilostazol and ACE inhibitors. The latter are prescribed for their antiatherogenic and vasodilating activity.
However, all these drugs provide only limited results in the treatment of claudication and sometimes induce side effects.
Therefore, exercise plays an essential role in the non-invasive treatment of patients with arterial disease of the lower limbs.
Several studies have established that regular exercise substantially improves the ability to walk. However, not all patients perform regular exercise of adequate intensity, mainly because it induces pain. Often, patients simply perform low-intensity exercise at a comfortable rhythm.
A recent multicentre, randomized study, published in JAMA, sought to assess whether low-intensity home exercise was able to improve walking ability in patients with peripheral arterial disease, compared to high-intensity exercise and compared to control subjects who did not completed any exercise.
305 patients were finally randomized, 48% were women, with an average age of 69 years. The study lasted 12 months.
During this period, both groups assigned to the exercise were asked to walk 5 times a week, for a maximum of 50 minutes per session, wearing an accelerometer to document exercise intensity and time.
The low-intensity group had to walk at a rhythm that caused no leg symptoms, while the high-intensity group had to walk at a pace that caused moderate to severe symptoms.
The main endpoint of the study was the change in walking distance in 6 minutes at 12 months. Secondary endpoints also included a biopsy of calf muscle at baseline and at 12-month follow-up.
In patients assigned to the low-intensity exercise group, the walking distance in the 6-minute test did not improved significantly, changing from 332.1 meters at the baseline visit to 327.5 meters at the 12-month visit. Even in the group that did not perform exercises the variation was not significant, changing from 328.1 to 317.5 meters.
In the high-intensity exercise group, the distance changed from 338.1 to 371.2 meters.
However, low-intensity exercise significantly improved the Walking Impairment Questionnaire distance and speed scores, at 6-month and 12-month follow-up, compared to the control group.
The authors ascribe this discrepancy to the fact that the participants knew which group they belonged to, and this may have influenced their questionnaire responses, or to an effect of low-intensity exercise, which may have encouraged a slower habitual walking pace, potentially reducing the 6-minute walking distance at follow-up. Finally, they argue that walking exercises, albeit at low intensity, may have influenced perception of walking ability, despite the lack of significant improvements in objective measures.
Among the participants who underwent calf muscle biopsy, no significant effects were found in either group who had exercised.
Overall, the results of this study seem to highlight the need to carry out physical exercise of adequate intensity to improve the walking ability of patients with peripheral arterial disease. Low-intensity exercise or no exercise seem to provide similar poor results.
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