Relationship between free-living daily physical activity and ambulatory measures in older claudicants.

The purpose of this study was to determine the relationship between free-living daily physical activity and ambulatory measurements in peripheral arterial occlusive disease (PAOD) patients with intermittent claudication. Thirty-four older, nonsmoking PAOD patients with intermittent claudication (age=69.0 +/- 6.0 years, ankle/brachial index [ABI] =0.63 +/- 0.18) were recruited from the Vascular Clinic at the Baltimore Veterans Affairs Medical Center and from radio and newspaper advertisements. Energy expenditure of physical activity (EEPA) was determined by using doubly labeled water and indirect calorimetry techniques. Patients were also characterized on claudication distances and peak oxygen uptake during a graded treadmill test, 6-minute walking distance, weight, body mass index, and percent body fat. The claudication patients were sedentary, as EEPA was 362 +/- 266 kcal/day. EEPA was related to the 6-minute walk distance (369 +/- 68 meters; r=0.629, P<0.001), to the number of steps taken during 6 minutes (605 +/- 99 steps; r=0.485, P=0.008), to the treadmill distance to maximal claudication (313 +/- 131 meters; r=0.470, P=0.010), and to the time to relief of pain (6:21 +/- 3:57 min:sec; r=-0.417, P=0.017). None of the other ambulatory and body composition measurements were correlated with EEPA. In conclusion, a reduction in free-living daily physical activity was associated with a decrease in ambulatory ability and with more severe intermittent claudication in older PAOD patients.

The effect of cigarette smoking on free-living daily physical activity in older claudication patients.

The purposes of this study were (1) to determine whether peripheral arterial occlusive disease (PAOD) patients who smoke have a lower free-living daily physical activity than nonsmoking patients and (2) to determine whether the difference in physical activity persisted after controlling for potential confounders such as PAOD severity, age, body composition, and peripheral circulation. Thirty-four smokers (45.5 +/-9.8 years of smoking) and 43 nonsmokers (former smokers who had a smoking history of 35.0 +/- 13.1 years who quit 12.2 +/- 10.5 years prior to investigation) were studied. Patients wore a Caltrac accelerometer and a pedometer on each hip over two consecutive weekdays to assess free-living daily physical activity. Patients were also characterized on age, weight, body mass index (BMI), percent body fat, ankle/brachial index (ABI), calf blood flow, and exercise capacity. The smoking and nonsmoking claudication patients had a similar level of PAOD severity, for no group differences were noted in ABI (P=0.287) and treadmill time to maximal claudication pain (P=0.201). However, the smokers were 35% less physically active than the nonsmokers (264 +/- 123 vs 407 +/- 272 kcal/day; P<0.006), and they took 23% fewer steps (4,116 +/- 2,199 vs 5,329 +/- 2,924 steps/day; P<0.034). After adjustment for group differences in age, weight, BMI, percent body fat, and calf blood flow, the lower activity level of the smokers persisted. The adjusted daily energy expenditure was 27% lower (292 +/- 105 vs 400 +/- 214 kcal/day; P=0.021), and the adjusted amount of daily walking was 29% lower (4,039 +/- 1,760 vs 5,684 +/- 2,235 steps/day; P=0.003). Smoking PAOD patients had a less physically active lifestyle than nonsmoking patients, and the lower activity level of the smokers was independent of PAOD severity, age, body composition, and peripheral circulation.

Improved walking economy in patients with peripheral arterial occlusive disease.

The effect of exercise rehabilitation on the oxygen cost of ambulation in patients with peripheral arterial occlusive disease (PAOD) was evaluated with specific emphasis on the effects of exercise rehabilitation on the slow component of VO2. Because the slow component of VO2 represents an increase in VO2 despite constant-intensity exercise, it can profoundly affect the relative energy cost of exercise in individuals with a low functional capacity. Twenty-six patients with intermittent claudication performed treadmill walking at 2.0 mph/0% grade for 20 min or until maximal claudication pain before and after 4 months of rehabilitation. The slow component of VO2 during the treadmill test was defined as the difference between the end-exercise VO2 and the VO2 observed at minute 3. Ankle/brachial systolic pressure index (ABI) was measured before and immediately following the exercise test. Rehabilitation consisted of 3 d x wk(-1) of treadmill walking for 15-30 min at 60-70% of VO2peak. The slow component of VO2 and end-exercise VO2 at pretraining (0.75 +/- 0.90 and 11.12 +/- 2.10 mL x kg[-1] x min[-1]) were significantly reduced after 4 months of exercise rehabilitation (-0.07 +/- 1.11 and 10.07 +/- 1.80 mL x kg[-1] x min[-1]; P < 0.05). Exercise rehabilitation also significantly (P < 0.05) increased the post-exercise ABI (pre-rehabilitation = 0.36 +/- 0.26, post-rehabilitation = 0.43 +/- 0.25). These data suggest that 4 months of exercise rehabilitation: 1) improves walking economy in PAOD patients because of a decreased slow component of VO2, and 2) increases post-exercise ABI.

Physical activity is related to ankle/brachial index in subjects without peripheral arterial occlusive disease.

The purpose of this study was to determine whether physical activity level was directly and independently related to the ankle/brachial systolic blood pressure index (ABI) in subjects without peripheral arterial occlusive disease (PAOD). A total of 353 subjects between the age of 38 and 88 years (63.7 +/- 9.1 years; mean +/- standard deviation) who had ABI values > or = 1.00 were studied. The sample consisted of 230 men and 123 women, of whom 274 were caucasian and 79 were African-American. Subjects were characterized on blood pressure, physical activity level from validated questionnaires, anthropometry, plasma lipoprotein lipids, and smoking history. The ABI (1.16 +/- 0.13) was related to physical activity obtained from the Minnesota Leisure Time Physical Activity (LTPA) questionnaire (r = 0.413, P < 0.001). Multiple regression analysis identified race, hypertension, current smoking status, and body mass index (BMI) as cardiovascular risk factors that were independently related to ABI. After controlling for these variables, the relationship between ABI and physical activity persisted (partial r = 0.329, P < 0.001). Thus, physical activity was positively related to ABI in subjects free of PAOD, and the relationship between physical activity and ABI persisted after controlling for race, hypertension, current smoking status, and BMI. It is concluded that adopting a physically active lifestyle is associated with a reduced risk of developing PAOD.

Physical activity monitoring in patients with peripheral arterial occlusive disease.

PURPOSE: Physical activity is an important variable to measure in patients with peripheral arterial occlusive disease (PAOD) because of this relationship to cardiovascular disease morbidity and mortality. The purposes of this study were to (1) determine the reliability of measures of daily physical activity in PAOD participants using an accelerometer and a pedometer; and (2) assess the validity of both instruments by comparing them against validated physical activity questionnaires. METHODS: Forty-three patients with PAOD with a resting ankle/brachial index of 0.63 +/- 0.19 were monitored for 2 consecutive weekdays with an accelerometer and pedometer worn on each hip. The 48-hour monitoring period was repeated approximately 1 week later. RESULTS: The daily physical activity values obtained from the accelerometer were similar between the two testing periods, 352 +/- 248 kcal/day vs. 337 +/- 199 kcal/day; P = 0.61, with a reliability coefficient of r = 0.84. The steps obtained from the pedometer during each 2-day period also were similar, 4615 +/- 2839 steps/day vs. 4498 +/- 2768 steps /day; P = 0.75, with a reliability coefficient of r = 0.86. The physical activity values from the accelerometer moderately correlated with the Minnesota Leisure Time Physical Activity Questionnaire, r = 0.33; P < 0.01, and the NASA/Johnson Space Center Physical Activity Scale, r = 0.44; P < 0.001. Similarly, the relationship between the steps obtained from the pedometer and physical Activity and the Minnesota Leisure Time Physical Activity and NASA/Johnson Space Center Physical Activity Scale questionnaires were significant, r = 0.46 and r = 0.51; P < 0.001, respectively. CONCLUSION: These findings indicate that an accelerometer and pedometer are two instruments that reliably estimate the physical activity levels of patients with PAOD over 2 consecutive days. Furthermore, the activity questionnaires, suggesting that activity monitoring measures a different component of activities in patients with PAOD with intermittent claudication.

Oxygen uptake during constant-intensity exercise in patients with peripheral arterial occlusive disease.

The purpose of the present study was to evaluate the oxygen uptake (VO2) response to walking in patients with peripheral arterial occlusive disease (PAOD) at a constant velocity and to determine whether the oxygen uptake observed during constant-intensity exercise in this population is associated with the severity of PAOD. Forty-nine PAOD patients with intermittent claudication were recruited (values are mean +/- SD) [age = 66.4 +/- 8.0 years, weight = 83.3 +/- 16.0 kg, body mass index = 28.8 +/- 5.6, ankle/brachial systolic blood pressure index (ABI) = 0.63 +/- 0.18, VO2peak = 13.02 +/- 2.99 ml/kg/min]. Patients were evaluated during a 2.0 miles/h walk on a treadmill until maximal claudication pain or for a maximum of 20 minutes. On average, patients walked for a duration of 10.3 +/- 5.8 min. Despite the constant absolute intensity during the exercise bout, there was a significant (p < 0.01) 4.0% increase in VO2 from min 3 of exercise (10.58 +/- 2.02 ml/kg/min) to min 5 (11.01 +/- 2.18 ml/kg/min) and a further 4.0% increase from min 5 to the end of exercise (11.46 +/- 2.32 ml/kg/min). Expressed as relative exercise intensity, this represented an increase from 80.8 +/- 18.3% to 87.1 +/- 18.0% of VO2peak from min 3 to the end of exercise. The magnitude of increase in VO2 during the exercise bout was not correlated with resting ABI (r = 0.00, p = 0.68) or post-exercise ABI (r = 0.04, p = 0.73). There was a nonsignificant trend towards a correlation between the time to onset of claudication pain and the magnitude of increase in VO2 (r = 0.25, p = 0.08). Results of this study suggest that an increase in VO2 occurs during constant-velocity walking at a high relative intensity in PAOD patients. This increase in VO2 does not appear to be related to the severity of PAOD.

The relationship between free-living daily physical activity and the severity of peripheral arterial occlusive disease.

The purposes of this study were to assess the magnitude of the reduction in free-living daily physical activity of claudicants compared with age-matched controls, and to examine the relationship between the severity of peripheral arterial occlusive disease (PAOD) and free-living daily physical activity. Eighty-five PAOD patients with intermittent claudication and 59 non-PAOD subjects with a resting ankle/brachial index (ABI) of 0.63 +/- 0.20 and 1.21 +/- 0.08, respectively, were monitored for 2 consecutive weekdays with an accelerometer and pedometer worn on each hip. The times to onset and to maximal claudication pain were also measured in the claudicants during a graded treadmill test to assess the functional limitations imposed by PAOD. The PAOD group had a 42% lower energy expenditure as measured from the accelerometer (357 +/- 238 kcal/day versus 616 +/- 363 kcal/day; p < 0.001) and a 45% lower pedometer reading (4737 +/- 2712 steps/day versus 8672 +/- 4235 steps/day; p < 0.001) than the non-PAOD group. Furthermore, the relationship between free-living daily physical activity and ABI in PAOD patients was significant for both the accelerometer (r = 0.41; p < 0.001) and the pedometer (r = 0.41; p < 0.001). The rate of decline in free-living daily activity was 42 kcal/day and 612 steps/day per 0.10 drop in ABI. The correlation between free-living daily physical activity and time to maximal claudication pain (6:25 +/- 3:30 min:s) in the PAOD group was significant for both the accelerometer (r = 0.30; p = 0.05) and the pedometer (r = 0.36; p = 0.03). However, the time to onset of claudication pain (3:02 +/- 2:22 min:s) in the PAOD group was not related to either the accelerometer (r = -0.02; p = 0.86) or the pedometer (r = 0.18; p = 0.28) activity values. In conclusion, free-living daily physical activity was 42% to 45% lower in PAOD patients with intermittent claudication than in apparently healthy subjects of similar age. Moreover, claudicants were progressively more sedentary with an increase in PAOD severity.