Most patients with intermittent claudication (IC) demonstrate a limited exercise performance and have increased risks on cardio- and cerebrovascular events, reduced quality of life (QoL) and higher mortality rates.1 Primary treatment of IC includes supervised exercise therapy (SET) as suggested by several international guidelines.1-3 SET significantly improves the maximal and pain-free walking distances and is cost-effective.4-8 However, the question arises whether effectiveness of PAD treatment modalities should be evaluated on the basis of changes in walking capacity only.
Individuals who are regularly physically active report better overall health, lower health care expenditures and fewer mobility limitations than their sedentary counterparts.9,10 The American Heart Association (AHA) and the American College of Sports Medicine (ACSM) provide specific recommendations of various types of activity to stimulate the elderly. Tailored recommendations are provided that apply to adults with clinically-significant chronic conditions or functional limitations that affect mobility and activity.11 Guidelines suggest to engage in moderate-intensity aerobic exercise for a minimum of 30 minutes during five days a week, or a minimum of 20 minutes of vigorous-intensity activity on three days each week, or some combination of the two.11 Activities should be performed in bouts of at least 10 minutes. Intensity of effort is assessed in absolute terms by estimating the actual metabolic cost of a given activity and assigning intensity accordingly.12 A metabolic equivalent (MET) is an estimate of oxygen consumption at rest. A three-MET activity would be an activity that utilizes roughly three times the amount of resting energy expenditure. Accordingly, vigorous intensity activities (>6.0 METs) performed for a particular duration and frequency generate greater energy expenditure than moderate-intensity activities (3.0-6.0 METs) of the same duration and frequency. When combining the recommendations on moderate- and vigorous-intensity physical activity (PA), the daily minimum goal of physical activity (PA) should be in the range of 64-107 METsmin.11
Recent studies demonstrated that free-living daily PA levels in IC patients are lower compared to healthy controls 13-16. However, PA is scantly used as an outcome parameter in trials concerning IC treatment 15,17-21. It may be relevant to study the potential beneficial effects of SET on PA level and exercise behaviour in IC patients. If PA levels improve following SET, cardiovascular risk reduction and improved QoL may follow on the long term 22,23. Although SET has proven effective in improving walking distances 8,19, one can question whether an increased walking capacity is of benefit during the patient's daily life activities. In other words, when an IC patient is able to walk further, this finding does not necessarily implicate that PA levels and/or exercise behavior are positively influenced. A potential goal of future PAD treatment should perhaps be aimed at increasing physical activity.
The aim of this study is to assess the effect of a SET program on PA and walking behavior in an IC population. In addition, we hypothesize that a SET induced increased walking distance would improve PA levels in IC patients.