Factors Associated with Sedentary Behavior in Patients with Intermittent Claudication.

OBJECTIVES: Time spent in sedentary behavior has been associated with cardio-metabolic risk factors in the general population and in patients with symptomatic peripheral artery disease (PAD). Given the association of sedentary behavior and poor health outcomes, it is important to identify factors associated with sedentary behavior in these patients. The aim of this study was to identify factors associated with the sedentary time in patients with symptomatic PAD. METHODS: The sample included 297 patients with symptomatic PAD. Sedentary behavior was assessed using a step activity monitor and the patients were divided into tertiles. Demographic data, body mass index, comorbid conditions, and measures of severity of PAD (ankle brachial index, ischemic window, claudication measurements, peak oxygen uptake and walking economy) were obtained. RESULTS: Patients in the highest tertile (i.e. more sedentary) had a higher body mass index and a higher prevalence of diabetes mellitus, metabolic syndrome, and obesity than patients in the lowest tertile, whereas their peak walking time, peak oxygen uptake, and walking economy were lower (p < .05 for all). Using multiple regression procedures, the factors associated with the sedentary time were male sex (b = .217, R2 = .180, p = .001), body mass index (b = .154, R2 = .059, p = .013), peak walking time (b = -.360, R2 = .066, p ≤ .001), and walking economy (b = -.187, R2 = .142, p = .004). CONCLUSION: In patients with symptomatic PAD, greater time spent in sedentary behavior was found in men, and in patients with higher body mass index, lower peak walking time, and lower walking economy.

Walking Economy is Impaired in Older Men and Women with Type 2 Diabetes.

OBJECTIVE: We compared the walking economy in older participants with and without type 2 diabetes. METHODS: Walking economy was determined in 115 older participants with type 2 diabetes and 130 older control participants without diabetes by continuously measuring oxygen uptake during a treadmill test in which the work rate was at a constant speed of 2 mph and a grade of 0% for a duration of 10 minutes. Participants also completed a Balke treadmill protocol for the determination of peak oxygen uptake, defined as the highest oxygen uptake value attained during the final work stage attained. Fractional utilization was then calculated as the walking economy oxygen uptake divided by peak oxygen uptake, expressed as a percentage. RESULTS: Compared to those without diabetes, participants with type 2 diabetes were older (p=0.042), had higher prevalence of men (p=0.034), obesity (p=0.010), chronic kidney disease (p=0.020), peripheral artery disease (p=0.024), and had a higher body mass index (p=0.025), and waist/hip ratio (p=0.006). After adjusting for these variables, the participants with diabetes had higher walking economy (p<0.001), fractional utilization (p<0.001), and lower peak oxygen uptake (p<0.001) than those without diabetes (p<0.001). CONCLUSIONS: Older men and women with type 2 diabetes are less economical when they ambulate at a given speed than compared to control participants without diabetes, independent of their greater co-morbid burden. The impaired walking economy in the diabetic participants is further magnified by their lower aerobic fitness, thereby leading to a higher fractional utilization of oxygen consumed during a given walking task.

Impaired balance and higher prevalence of falls in subjects with intermittent claudication.

BACKGROUND: The purpose of this study was to determine whether peripheral arterial disease (PAD) subjects have impaired balance and a higher prevalence of falls than non-PAD controls and to determine whether balance and falls are related to the severity of PAD and functional status. METHODS: A total of 367 PAD subjects (aged 68 +/- 1 years; mean +/- SEM) and 458 non-PAD controls (aged 67 +/- 1 years) were recruited. Unipedal stance time, history of ambulatory stumbling and unsteadiness, and history of falling were recorded. Additionally, subjects were characterized on age, ankle/brachial index (ABI), anthropometry, measured and self-reported ambulatory function, and monitored daily physical activity. RESULTS: Unipedal stance time was 28% shorter ( p <.001) in the PAD subjects than in the non-PAD controls (15.9 +/- 0.9 vs 22.1 +/- 1.0). History of ambulatory stumbling and unsteadiness was 86% more prevalent ( p <.001) in the PAD group (150/367 = 41%) than in the controls (101/458 = 22%), and history of falling was 73% more prevalent ( p <.001) in the PAD subjects (95/367 = 26%) than in the controls (69/458 = 15%). Within the PAD group, 6-minute walk distance, self-reported ambulatory function, and daily physical activity were significantly related to the balance and falling measures ( p <.05), whereas ABI was unrelated ( p >.05). CONCLUSIONS: Compared with the controls, PAD subjects with intermittent claudication had impaired balance and a greater likelihood of falling, both of which were associated with ambulatory function and daily physical activity.

Measuring fitness in healthy older adults: the Health ABC Long Distance Corridor Walk.

OBJECTIVES: The Health ABC Long Distance Corridor Walk (LDCW) was designed to extend the testing range of self-paced walking tests of fitness for older adults by including a warm-up and timing performance over 400 meters. This study compares performance on the LDCW and 6-minute walk to determine whether the LDCW encourages greater participant effort. DESIGN: Subjects were administered the LDCW and 6-minute walk during a single visit. Test order alternated between subjects, and a 15-minute rest was given between tests. SETTING: The Baltimore Veterans Affairs Medical Center. PARTICIPANTS: Twenty volunteers age 70 to 78. MEASUREMENTS: The LDCW, consisting of a 2-minute warm-up walk followed by a 400-meter walk and a 6-minute walk test were administered using a 20-meter long course in an unobstructed hallway. Heart rate (HR) and blood pressure (BP) were recorded at rest and before and after all walks. RESULTS: All 20 subjects walked a faster pace over 400 meters than for 6 minutes, in which the mean distance covered was 402 meters. From paired t-tests, walking speed was faster (mean difference = 0.23 m/sec; P < .001), and ending HR (mean difference = 7.6 bpm; P < .001) and systolic BP (mean difference = 8.3 mmHg; P = .024) were greater for the 400-meter walk than for the 6-minute walk. Results were independent of test order and subject fitness level. CONCLUSIONS: Providing a warm-up walk and using a target distance instead of time encouraged subjects to work closer to their maximum capacity. This low-cost alternative to treadmill testing can be used in research and clinical settings to assess fitness and help identify early functional decline in older adults.

The relationship between history of falling and physical function in subjects with peripheral arterial disease.

The purpose of this study was to determine whether peripheral arterial disease (PAD) subjects with a history of falling had more impaired physical function than their non-falling counterparts. A total of 120 PAD subjects (26%) who had fallen over the past year and 346 PAD subjects (74%) who had not fallen were evaluated. Additionally, subjects were characterized on physical function, consisting of balance, strength, ambulatory function, and monitored physical activity, as well as PAD-specific measures of ankle/brachial pressure index (ABPI) and treadmill claudication distances. Full-tandem stance time was 19% shorter (p < 0.001) in the fallers than in the non-fallers (7.2 +/- 0.3 vs 8.9 +/- 0.1 s; mean +/- SEM), and the self-reported ability to climb stairs was 36% lower (27 +/- 4 vs 42 +/- 2%). Furthermore, the fallers were 126% more likely (p < 0.001) to report ambulatory stumbling and unsteadiness, took 14% longer (p = 0.022) to perform five sequential sit-to-stand transfers using an armless chair, covered 16% shorter distance (p < 0.001) during a 6-min walk test, and were 25% less physically active than the non-fallers. The groups had similar ABPI and treadmill claudication distances (p < 0.05). A history of falling was independently related to the self-reported ability to climb stairs, the full-tandem stance time, self-reported ambulatory stumbling and unsteadiness, and daily physical activity (multiple R = 0.47, p < 0.001). In conclusion, impairments in multiple domains of physical function were associated with a history of falling in PAD subjects with intermittent claudication. Furthermore, the link between poor physical function and falling was independent of PAD severity.

Smoking history is related to free-living daily physical activity in claudicants.

PURPOSE: To determine whether smoking history was related to free-living daily physical activity in peripheral arterial occlusive disease (PAOD) patients with intermittent claudication, and whether the effect of smoking history on physical activity level persisted after controlling for group differences in ambulatory function, peripheral circulation, and body composition. METHODS: Patients were separated into three groups: those who never smoked (N = 35), those who had a lower pack-year history of smoking (< or =40 pack-yr; N = 33), and those who had a higher pack-year history (>40 pack-yr; N = 30). Free-living daily physical activity was assessed by activity monitors (an accelerometer and a pedometer) worn on each hip over 2 consecutive weekdays. Patients also were characterized on ambulatory function, peripheral circulation, and body composition because of their relationship with physical activity. RESULTS: A progressive decline (P < 0.001) in free-living daily physical activity with increasing smoking exposure was obtained from the accelerometer in the nonsmokers (482 +/- 36 kcal x d(-1); mean +/- SE), smokers with a lower pack-year history (361 +/- 37 kcal x d(-1)), and smokers with a higher pack-year history (227 +/- 23 kcal x d(-1)). A similar decline was found with the pedometer data (P < 0.001). After controlling for group differences in 6-min walk distance and in calf transcutaneous heating power, group differences in free-living daily physical activity were no longer significant. CONCLUSION: Progressive decrements in free-living daily physical activity with greater levels of smoking exposure in PAOD patients are primarily due to smoking-related impairments in ambulatory function and peripheral circulation.

Relationship between free-living daily physical activity and peripheral circulation in patients with intermittent claudication.

The purpose of this study was to determine the relationship between free-living daily physical activity and peripheral circulation under resting, reactive hyperemia, and maximal exercise conditions in peripheral arterial occlusive disease (PAOD) patients with intermittent claudication. Sixty-one PAOD patients (age = 70 +/- 6 years, ankle/brachial index [ABI] = 0.57 +/- 0.24) were recruited from the Vascular Clinic at the Baltimore Veterans Affairs Medical Center and from radio and newspaper advertisements. Free-living daily physical activity was measured as the energy expenditure of physical activity (EEPA), determined from doubly labeled water and indirect calorimetry. Patients also were characterized on ankle/brachial index, calf blood flow, calf transcutaneous oxygen tension (TcPO2), and calf transcutaneous heating power (TcHP). ABI and calf blood flow served as markers of the macrocirculation of the lower extremity, while TcPO2 and TcHP served as markers of the microcirculation. The claudication patients were sedentary, reflected by a mean EEPA value of 486 +/- 274 kcal/day. EEPA was related to calf TcHP at rest (282 +/- 24 mW; r = -0.413, p = 0.002), after postocclusion reactive hyperemia (275 +/- 22 mW; r = -0.381, p = 0.004), and after maximal exercise (276 +/- 20 mW; r = -0.461, p<0.001). ABI, calf blood flow, and calf TcPO2 were not related to EEPA under any condition. In conclusion, higher levels of free-living daily physical activity were associated with better microcirculation of the calf musculature in older PAOD patients with intermittent claudication.

Cigarette smoking shortens the duration of daily leisure time physical activity in patients with intermittent claudication.

PURPOSE: The authors determined (1) whether peripheral arterial occlusive disease (PAOD) patients who smoke have a reduction in either the duration or intensity of daily physical activities compared with nonsmoking patients, and (2) whether group differences in the pattern of physical activity persisted after controlling for potential confounding variables. METHODS: A total of 170 smokers and 201 nonsmokers who had quit smoking for at least 1 year prior to investigation were studied. Physical activity patterns were measured using the Minnesota Leisure Time Physical Activity (LTPA) questionnaire. Patients also were characterized on potential covariates such as demographics, comorbid conditions, cardiovascular risk factors, ambulatory measures, peripheral hemodynamics, and anthropometric measures. RESULTS: The smokers were 37% less physically active than the nonsmokers (87 +/- 90 versus 139 +/- 121 kcal/day; P = 0.027). The reduced total LTPA in the smokers was due to a 28% shorter duration of performing activities (26 +/- 7 versus 36 +/- 22 min/day; P = 0.031), and a 3% lower mean intensity of the activities (3.3 +/- 1.0 versus 3.8 +/- 0.8 kcal/min; P = 0.038). The distance score on the Walking Impairment Questionnaire and the hip circumference were significant covariates of the LTPA measures. After adjusting for these covariates, the total LTPA remained 29% lower in the smokers (P = 0.039), the mean daily duration of LTPA remained 20% lower (P = 0.043), but the mean intensity of LTPA was no longer different between the groups. CONCLUSION: Compared with their nonsmoking counterparts, claudicants who smoke have a reduced total LTPA because they engage in activities of similar intensity for a shorter duration of time.

Comparison of three blood pressure methods used for determining ankle/brachial index in patients with intermittent claudication.

The standard noninvasive test to assess the severity of peripheral arterial occlusive disease (PAOD) is the ankle/brachial systolic blood pressure index (ABI). While ankle systolic blood pressure is obtained by the Doppler ultrasound technique, brachial systolic blood pressure can be obtained by the Doppler, auscultatory, or oscillometric (Dinamap 1846 SX) methods. The purpose was to determine whether the three methods yielded similar brachial systolic blood pressure values, and consequently similar ABI values, in PAOD patients with intermittent claudication. Fifty patients who had a history of intermittent claudication of 2.3 +/- 2.0 blocks for a duration of 5.7 +/- 5.8 years were recruited. Following 10 minutes of supine rest, brachial systolic blood pressure was measured in the right arm by the three techniques in a randomized order, and ankle systolic blood pressure (87.3 +/- 28.9 mmHg) was measured in the more symptomatic leg with the Doppler technique. Brachial systolic blood pressure was not significantly different (p=0.954) among the Doppler (128.5 +/- 18.4 mmHg), auscultatory (128.4 +/- 17.4 mmHg), and oscillometric (128.2 +/- 17.1 mmHg) methods. Corresponding ABI values also were similar (p=0.922) among the three respective methods (0.68 +/- 0.22, 0.68 +/- 0.22, and 0.68 +/- 0.21), indicating that ABI did not vary according to the technique used to obtain brachial systolic blood pressure. It is concluded that the accuracy of determining ABI in PAOD patients with intermittent claudication was minimally affected by the method chosen to obtain brachial systolic blood pressure.

The clinical utility of a six-minute walk test in peripheral arterial occlusive disease patients.

OBJECTIVES: To determine the test-retest reliability of the distance covered and the steps taken to complete a 6-minute walk test by peripheral arterial occlusive disease (PAOD) patients with intermittent claudication. To determine the relationship between the total distance and steps covered during the 6-minute walk test and clinical measures of PAOD severity. DESIGN: Cross-sectional design. SETTING: The Claude Pepper Older Americans Independence Center at the University of Maryland at Baltimore. PARTICIPANTS: Sixty-four PAOD patients between the ages of 45 and 88 years (age = 68 +/- 7 years, ankle/brachial index (ABI) = .61 +/- .19) were recruited from the Vascular Clinic at the Baltimore Veterans Affairs Medical Center and from radio and newspaper advertisements. MEASUREMENTS: Patients were assessed on a 6-minute walk test and a treadmill graded exercise test. A second 6-minute walk test was administered approximately 1 week later. Patients also were characterized in regard to blood pressure in the arms and legs, ABI, anthropometry, body composition, and physical activity. RESULTS: The distances walked during the two 6-minute walk tests were similar (350 +/- 78 m vs 360 +/- 73 m), resulting in a high reliability coefficient (R = .94) and a low coefficient of variation (10.4%). The total steps taken during the 6-minute walk test also were similar (562 +/- 113 steps vs 587 +/- 107 steps), resulting in a high reliability coefficient (R = .90) and a low coefficient of variation (11.7%). Furthermore, the 6-minute walking distance correlated with the distances to onset (r = .346, P = .007) and with maximal claudication pain (r = .525, P < .001) during the treadmill test as well as with ABI (r = .552, P < .001). CONCLUSION: The 6-minute walk test yields highly reliable measurements, which are related to the functional and hemodynamic severity of PAOD, in patients with intermittent claudication.

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.

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.