Patterns of ambulatory activity in subjects with and without intermittent claudication

Association of mental health with walking capacity in patients with claudication: a cross-sectional study

OBJECTIVES

The purpose of this investigation was to verify the association between mental health (MH) indicators with walking capacity in patients with PAD.

METHODS

Two hundred and forty-six patients with PAD and claudication symptoms participated in this study. Physical function was assessed objectively with the 6-min walk test (6MWT) and subjectively using the Walking Impairment Questionnaire (WIQ). MH was assessed by the World Health Organization Quality of Life-Bref (WHOQOL-Bref) (six questions were selected - 1, 2, 10, 16, 19, and 26). Patients were divided into tertile groups according to their composite z-score for mental health (Low MH, Middle MH, and High MH).

RESULTS

The High MH group presented higher scores (p < 0.05) for the WIQ (distance = 26.8 ± 25.6, speed = 25.4 ± 17.3, and stairs = 33.6 ± 27.5), claudication onset distance (161.6 ± 83.6 m), and total walking distance (352.9 ± 79.6 m) compared to Low MH (WIQ distance = 14.8 ± 16.2, 17.7 ± 13.0, and stairs = 22.7 ± 20.7). Additionally, the High MH group presented a longer claudication onset distance (115.5 ± 70.5 m), and total walking distance in 6MWT (306.6 ± 83.2 m), and higher scores in the total walking distance compared to Middle MH (309.5 ± 93.6 m) (p < 0.05).

CONCLUSION

In patients with PAD, MH was positively associated with walking capacity. Based on these results, treatments that can improve mental health, through different mechanisms, can also positively influence the ability of these patients to walk.

Factors Associated With Physical Inactivity of Recipients of a Kidney Transplant: Results From the ADHERE BRAZIL Multicenter Study

OBJECTIVE

Physical activity is recommended for recipients of a kidney transplant. However, ADHERE BRAZIL study found a high prevalence (69%) of physical inactivity in Brazilian recipients of a kidney transplant. To tackle this behavior, a broad analysis of barriers is needed. This study aimed to identify factors (patient and transplant center levels) associated with physical inactivity among recipients of a kidney transplant.

METHODS

This was a subproject of the ADHERE BRAZIL study, a cross-sectional, multicenter study of 1105 recipients of a kidney transplant from 20 kidney transplant centers. Using a multistage sampling method, patients were proportionally and randomly selected. Applying the Brief Physical Activity Assessment questionnaire, patients were classified as physically active (≥150 min/wk) or physically inactive (<150 min/wk). On the basis of an ecological model, 34 factors associated with physical inactivity were analyzed by sequential logistic regression.

RESULTS

At the patient level, physical inactivity was associated with smoking (odds ratio = 2.43; 95% CI = 0.97-6.06), obesity (odds ratio = 1.79; 95% CI = 1.26-2.55), peripheral vascular disease (odds ratio = 3.18; 95% CI = 1.20-8.42), >3 posttransplant hospitalizations (odds ratio = 1.58; 95% CI = 1.17-2.13), family income of >1 reference salary ($248.28 per month; odds ratio = 0.66; 95% CI = 0.48-0.90), and student status (odds ratio = 0.58; 95% CI = 0.37-0.92). At the center level, the correlates were having exercise physiologists in the clinical team (odds ratio = 0.54; 95% CI = 0.46-0.64) and being monitored in a teaching hospital (undergraduate students) (odds ratio = 1.47; 95% CI = 1.01-2.13).

CONCLUSIONS

This study identified factors associated with physical inactivity after kidney transplantation that may guide future multilevel behavioral change interventions for physical activity.

IMPACT

In a multicenter sample of recipients of a kidney transplant with a prevalence of physical inactivity of 69%, we found associations between this behavior and patient- and center-level factors. At the patient level, the chance of physical inactivity was positively associated with smoking, obesity, and patient morbidity (peripheral vascular disease and hospitalization events after kidney transplantation). Conversely, a high family income and a student status negatively correlated with physical inactivity. At the center level, the presence of a dedicated professional to motivate physical activity resulted in a reduced chance of physical inactivity. A broad knowledge of barriers associated with physical inactivity can allow us to identify patients at a high risk of not adhering to the recommended levels of physical activity.

Effects of ankle-foot orthoses on step activities in the community: a systematic review

PURPOSE

To determine the effects of ankle-foot orthoses (AFO) on step-based physical activities in individuals with neurological, orthopaedic, or cardiovascular disorders.

METHODS

Electronic searches of databases such as Scopus, PubMed, Web of Science, Embase, ProQuest, Cochrane Library, and EBSCO were conducted. Two evaluators independently searched with keywords focusing on step-based physical activities, and either articulated or non-articulated AFO. Study quality was assessed using a modified Downs and Black quality scale.

RESULTS

Eleven studies that met the inclusion criteria were selected, including four being classified as good, four as fair, and three as poor in quality. The majority of these trials found no significant effects of AFO on step activities. Only a few studies reported improvements in step counts and active times in step activity with a limited to moderate level of evidence. Subjective evaluations such as user satisfaction, and physical functionality during step activity, on the other hand, showed substantial changes with the use of AFO interventions, although there was no evidence of improvement in the quality of life.

CONCLUSIONS

Although the AFO did not seem to have a substantial effect on step activity, it appeared to play a vital role in improving the patient satisfaction level of step activity.IMPLICATIONS FOR REHABILITATIONAnkle-foot orthoses (AFO) may not significantly affect the step activity of individuals with impaired ankle-foot complex.AFO may enhance patient-reported satisfaction, physical functioning, participation, and fatigue level during step activity.The patient's perception that the AFO is beneficial is in contrast to objective data showing no significant increase in real-world activity.

Effects of Long-Term Home Exercise in Participants With Peripheral Artery Disease

Background This randomized controlled trial compared long-term changes in peak walking time (PWT) and exercise time-to-minimum calf muscle oxygen saturation (StO2) in symptomatic participants with peripheral artery disease following a long-term home exercise program (HEP), a short-term supervised exercise therapy (SET) program that transitioned to a long-term HEP (SET/HEP), and a control intervention. Methods and Results For the first 3 months, HEP and SET/HEP groups performed intermittent walking to mild-to-moderate claudication pain, whereas the control group performed light resistance training. For the subsequent 15 months, the HEP group continued their exercise program, the SET/HEP group transitioned from SET to the HEP program, and the control group transitioned to only receive walking advice. PWT increased significantly from baseline to month 18 in the HEP group (408±279 meters to 814±393 meters, P<0.001) and in the SET/HEP group (457±288 meters to 818±313 meters, P<0.001). Exercise time-to-minimum calf muscle StO2 increased significantly from baseline to month 18 in the HEP group (238±241 seconds to 497±485 seconds, P<0.05) and in the SET/HEP group (296±289 seconds to 620±450 seconds, P<0.001). These changes in PWT and exercise time-to-minimum calf muscle StO2 were greater than in the control group (P<0.001 and P<0.01, respectively). Additionally, the change in exercise time-to-minimum calf muscle StO2 was correlated with the change in PWT in both exercise groups combined (r=0.601, P=0.0015). Conclusions Long-term HEP and SET/HEP were efficacious in improving PWT and exercise time-to-minimum calf muscle StO2 in symptomatic participants with peripheral artery disease, and these changes were correlated with each other. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT00618670.

Clinical Effectiveness of a Supervised Exercise Therapy Program for Treatment of Peripheral Artery Disease: A Translational Study

PURPOSE

National guidelines for the treatment and management of symptomatic peripheral artery disease (PAD) recommend supervised exercise therapy (SET) as a first line of therapy. However, it is unknown how these expert opinion-based SET guidelines work in clinical practice as SET programs become established following the 2017 Centers for Medicare & Medicaid Services coverage announcement. The purpose of this prospective, nonrandomized translational study was to evaluate the clinical effectiveness of a SET program and specifically walking exercise modalities that did not incorporate a treadmill (TM).

METHODS

Participants enrolled in a 12-wk SET program housed in four rural Midwest cardiac rehabilitation settings and were prescribed an exercise program by an exercise physiologist or nurse based on current SET guidelines. Groups included TM walking, total body recumbent stepping (TBRS), TM walking + TBRS, and multimodal. Pre- and post-tests of walking capacity, physical function, and quality of life were administered.

RESULTS

The sample (n = 93) was all White, with 55% female representation, age of 73.7 ± 9.0 yr, and mild-moderate PAD (ankle-brachial index = 0.71 ± 0.19). Collectively, SET significantly improved the 6-min walk test (32.1 ± 6.6 m; P < .01). Within-group changes in the 6-min walk test were seen for all groups except the multimodal group; there were no significant between-group differences in change scores ( P = .30). No significant between-group changes were seen for the TM walking, TBRS, and TM walking + TBRS groups for physical function measures.

CONCLUSION

This study demonstrates the clinical effectiveness of SET programs following current guidelines and potential utilization of non-TM walking modalities in SET programs.

Effects of aerobic and combined training on pain-free walking distance and health-related quality of life in patients with peripheral artery disease: a randomized clinical trial

Background

Decreased walking ability in patients with peripheral arterial disease is often a clinical problem and limits the quality of life and daily activities of these subjects. physical exercise is important in this scenario, as it improves both the daily walking distance and the ability to withstand intermittent claudication related to the limitations of the peripheral disease.

Objectives

Our aim was to compare the effects of two types of exercise training (aerobic training and aerobic training combined with resistance exercises) on pain-free walking distance (PFWD) and health-related quality of life (HRQoL) in a sample composed of patients with peripheral artery disease (PAD).

Methods

Twenty patients with claudication symptoms were randomized to either aerobic control (AC) N= 9, or combined training (CT) N= 8, (24 sixty-minute sessions, twice a week). The total walking distance until onset of pain due to claudication was assessed using the 6-minute walk test and HRQoL was measured using the WHOQOL-bref questionnaire (general and specific domains) at baseline and after training. We used generalized estimating equations (GEE) to assess the differences between groups for the PFWD and HRQoL domains, testing the main group and time effects and their respective interaction effects. P values < 0.05 were considered statistically significant.

Results

Seventeen patients (mean age 63±9 years; 53% male) completed the study. Both groups experienced improvement in claudication, as reflected by a significant increase in PFWD: AC, 149 m to 299 m (P<0.001); CT, 156 m to 253 m (P<0.001). HRQoL domains also improved similarly in both groups (physical capacity, psychological aspects, and self-reported quality of life; P=0.001, P=0.003, and P=0.011 respectively).

Conclusions

Both aerobic and combined training similarly improved PFWD and HRQoL in PAD patients. There are no advantages in adding strength training to conventional aerobic training. This study does not support the conclusion that combined training is a good strategy for these patients when compared with classic training.

Walking Behaviour of Individuals with Intermittent Claudication Compared to Matched Controls in Different Locations: An Exploratory Study

Individuals with intermittent claudication (IC) are less physically active than their peers, but how this varies with location is unclear. Individuals with IC and matched controls [sex, age ±5 years, home < 5 miles] wore an activity monitor (activPAL) and carried a GPS device (AMOD-AGL3080) for 7 days. GPS data categorised walking events as occurring at home (<=50 m from home co-ordinates) or away from home, and indoors (signal to noise ratio <= 212 dB) or outdoors. Number of walking events, walking duration, steps and cadence were compared between groups and each location pair using mixed model ANOVAs. In addition, the locus of activity (distance from home) at which walking was conducted was compared between groups. Participants (n = 56) were mostly male (64%) and aged 54-89 years. Individuals with IC spent significantly less time walking and took fewer steps than their matched controls at all locations, including at home. Participants spent more time and took more steps away from home than at home, but were similar when walking indoors and outdoors. The locus of activity was significantly smaller for individuals with IC, suggesting that it is not just physical capacity that influences walking behaviour, and other factors (e.g., social isolation) may play a role.

Diabetes Is Negatively Associated With Meeting Physical Activity Time-Intensity Guidelines in Patients With Claudication

PURPOSES

We determined the percentage of patients with peripheral artery disease (PAD) and claudication who meet the 2018 physical activity (PA) time-intensity guidelines, and we identified the clinical characteristics associated with the status of meeting the guidelines.

METHODS

Five hundred seventy-two patients were assessed on their daily ambulatory activity for 1 wk with a step activity monitor, and were evaluated on whether or not they achieved 150 min/wk of moderate-intensity PA.

RESULTS

Thirty-one percent (n = 175) of the patients with PAD met the PA time-intensity guidelines and 69% (n = 397) did not. In a final multivariable logistic regression model identifying the independent predictors of meeting the PA time-intensity guidelines from clinical characteristics, diabetes was the only significant variable entered (OR = 0.310: 95% CI, 0.175-0.538; P < .001) and was associated with a 69% lower chance of meeting the guidelines. Patients with diabetes spent less daily time in moderate-intensity ambulatory PA than patients without diabetes (15 ± 13 vs 23 ± 20 min/d; P < .001).

CONCLUSIONS

Thirty-one percent of patients with PAD and claudication met the PA time-intensity guidelines. Furthermore, patients with diabetes were least likely to meet the PA time-intensity guidelines, as they had a 69% lower chance than patients without diabetes. The clinical significance is that PAD patients who have diabetes are particularly susceptible to being physically sedentary, and are therefore prime patients who should be encouraged to increase their daily PA.

Maximal calf conductance is associated with 6-minute walk distance in participants with and without peripheral artery disease

INTRODUCTION

The aims were (a) to compare the maximal calf conductance and 6-minute walk distance of participants with and without peripheral artery disease (PAD) and claudication, (b) to determine whether maximal calf conductance was more strongly associated with 6-minute walk distance in participants with PAD than in the controls, and (c) to determine whether this association was significant in participants with PAD after adjusting for ABI, as well as for demographic, anthropometric, and comorbid variables.

METHODS

Participants with PAD (n = 633) and without PAD (n = 327) were assessed on maximal calf conductance using venous occlusion plethysmography, and on 6-minute walk distance. Participants were further characterized on ABI, and on demographic, anthropometric, and comorbid variables.

RESULTS

The PAD group had lower maximal calf conductance than the control group (0.136 ± 0.071 vs 0.201 ± 0.113 mL/100 mL/min/mmHg, p < 0.001). Additionally, the PAD group had a lower 6-minute walk distance (375 ± 98 m vs 480 ± 107 m, p < 0.001). Maximal calf conductance was positively associated with 6-minute walk distance in both groups (p < 0.001) and was more strongly associated in the PAD group (p < 0.001). In adjusted analyses, maximal calf conductance remained positively associated with 6-minute walk distance in the PAD group (p < 0.001) and in the control group (p < 0.001).

CONCLUSIONS

Participants with PAD and claudication had impaired maximal calf conductance and a lower 6-minute walk distance than those without PAD, and maximal calf conductance was positively and independently associated with 6-minute walk distance within each group before and after adjusting for ABI, and for demographic, anthropometric, and comorbid variables.

Smart Wearable Systems for the Remote Monitoring of Selected Vascular Disorders of the Lower Extremity: A Systematic Review

This systematic review aims at providing an overview of the state of the art regarding smart wearable systems (SWS) applications to monitor the status of patients suffering from vascular disorders of the lower extremity. Peer-reviewed literature has been analyzed to identify employed data collection methods, system characteristics, and functionalities, and research challenges and limitations to be addressed. The Medline (PubMed) and SCOPUS databases were considered to search for publications describing SWS for remote or continuous monitoring of patients suffering from intermittent claudication, venous ulcers, and diabetic foot ulcers. Publications were first screened based on whether they describe an SWS applicable to the three selected vascular disorders of the lower extremity, including data processing and output to users. Information extracted from publications included targeted disease, clinical parameters to be measured and wearable devices used; system outputs to the user; system characteristics, including capabilities of remote or continuous monitoring or functionalities resulting from advanced data analyses, such as coaching, recommendations, or alerts; challenges and limitations reported; and research outputs. A total of 128 publications were considered in the full-text analysis, and 54 were finally included after eligibility criteria assessment by four independent reviewers. Our results were structured and discussed according to three main topics consisting of data collection, system functionalities, and limitations and challenges.

Association Between Meeting Physical Activity Time-Intensity Guidelines With Ambulation, Quality of Life, and Inflammation in Claudication

PURPOSE

The aim of this investigation was to determine if meeting the 2018 physical activity (PA) time-intensity guidelines was associated with better ambulatory function, health-related quality of life (HRQoL), vascular function, and inflammation than failing to meet the guidelines in patients with peripheral artery disease and claudication. Second, we determined the optimal number of total steps/d and steps taken at moderate cadence needed to meet the PA time-intensity guidelines.

METHODS

Five hundred seventy-two patients were assessed on daily ambulatory activity for 1 wk with a step activity monitor, and were grouped according to whether they achieved <150 min/wk of moderate-intensity PA (group 1 = do not meet guidelines; n = 397) or whether they were above this threshold (group 2 = meet guidelines; n = 175).

RESULTS

Treadmill peak walking time (mean ± SD) was higher ( P < .001) in group 2 (709 ± 359 sec) than in group 1 (427 ± 281 sec). The physical function HRQoL score was higher ( P < .001) in group 2 (61 ± 22%) than in group 1 (44 ± 21%). High-sensitivity C-reactive protein was lower ( P < .001) in group 2 (3.6 ± 4.5 mg/L) than in group 1 (5.9 ± 6.1 mg/L). Finally, ≥7675 total steps/d and ≥1660 steps/d at moderate cadence were optimal thresholds associated with meeting PA guidelines.

CONCLUSIONS

Patients with claudication who meet the 2018 PA time-intensity guidelines for US adults had better ambulation, HRQoL, and vascular outcomes than those who failed to meet the PA guidelines. Patients with claudication best achieved the PA time-intensity guidelines by taking ≥7675 total steps/d, and ≥1660 steps/d at a moderate cadence.

Self-Selected Walking Cadence after 16-Week Light-Intensity Physical Activity Intervention for Older Cancer Survivors

In this secondary analysis of a light-intensity physical activity intervention, we hypothesized that older cancer survivors would self-select a faster walking cadence to meet their daily step goals. Average steps/day and free-living walking cadence were measured in 41 participants (age 69 ± 3.1 years) with an ActivPAL monitor worn 7 days pre- and post-intervention. Besides peak and average walking cadence, stepping patterns associated with ambulatory intensity were sorted in cadence bands of 20 steps/min from 40−59 (incidental movement) to ≥120 steps/min (fast locomotor movement). Compared to the waitlist Control group (n = 17), the Intervention group (n = 24) increased their peak 30-min cadence (4.3 vs. 1.9 steps/minute; p = 0.03), average 10-min cadence (4.1 vs. −6.6 steps/minute; p = 0.04), and average 30-min cadence (5.7 vs. −0.8 steps/minute, p = 0.03). Steps taken in cadence bands denoting moderate-intensity physical activity (100−119 steps/min) increased by 478 (interquartile range (IQR): −121 to 1844) compared to decreasing by 92 (IQR: −510 to 181) steps/day for the intervention and Control groups, respectively (p < 0.01). Evaluation of free-living walking cadence and patterns of ambulatory behavior can inform future interventions targeting behavior change, especially in those populations most at risk for reduced physical activity and vulnerable to mobility deficits and loss of independence.

Minimal clinically important differences in daily physical activity outcomes following supervised and home-based exercise in peripheral artery disease

Introduction: We estimated minimal clinically important differences (MCID) for small, moderate, and large changes in daily step counts and time spent in moderate-to-vigorous physical activity (MVPA) following both supervised and home-based exercise programs in symptomatic patients with peripheral artery disease (PAD). Methods: Patients were randomized to either 12 weeks of a supervised exercise program (n = 60), a home-based exercise program (n = 60), or an attention-control group (n = 60). Results: Using the anchor-based method to determine MCID, the MCID value for a large change in health-related quality of life (HRQoL) was an increase of 1211 total daily steps and an increase in 11 minutes in the time spent in MVPA following 12 weeks of exercise intervention. Using the distribution-based method, the MCID values for small, moderate, and large changes in total daily steps in the home-based exercise group were 558, 1396, and 2233 steps/d, respectively, and the corresponding changes in the time spent in MVPA were 6, 15, and 23 minutes. Similar distribution-based MCID scores were noted for the supervised exercise group. Conclusion: Following 3 months of home-based and supervised exercise programs for patients with PAD and claudication, increases of 11 minutes in time spent in MVPA and 1211 total daily steps were associated with large anchor-based MCID increases in HRQoL. The clinical implication is that patients with PAD and claudication should be encouraged to increase daily steps, particularly by walking an additional 11 minutes each day in MVPA, which is associated with a large meaningful increase in HRQoL.

LIGHT AND MODERATE INTENSITY PHYSICAL ACTIVITY ARE ASSOCIATED WITH BETTER AMBULATION, QUALITY OF LIFE, AND VASCULAR MEASUREMENTS IN PATIENTS WITH CLAUDICATION

OBJECTIVES

To determine whether patients with claudication who reported performing either light-intensity physical activity (LPA) or moderate-to-vigorous intensity physical activity (MVPA) had higher levels of objectively-determined physical activity, and better physical function, health-related quality of life (HRQoL), and vascular measures, consisting of exercise time to minimum calf muscle oxygen saturation (StO₂) and high-sensitivity C-reactive protein, than patients who reported being physically sedentary.

METHODS

Two hundred sixty-nine patients were assessed on the Johnson Space Center physical activity scale. Patients were grouped according to whether they performed no physical activities (n=75), LPA (n=140), or MVPA (n=54). Primary measurements were total daily steps obtained from a step activity monitor worn for one week, peak walking time obtained from a treadmill test, the physical function score on the Medical Outcomes Study Short-Form 36 survey to assess HRQoL, and high-sensitivity C-reactive protein.

RESULTS

Total daily steps (mean±SD) was significantly different among groups, as both the LPA group (7878±2808 steps/day) and the MVPA group (8551±3365 steps/day) took more daily steps (p<0.01) than the sedentary group (3323±986 steps/day). Treadmill peak walking time was significantly different among groups, as both the LPA group (433±296 sec) and the MVPA group (548±300 sec) had greater peak walking time (p<0.01) than the sedentary group (302±210 sec). Physical function score was significantly different among groups, as both the LPA group (44±20%) and the MVPA group (58±19%) had higher scores (p<0.01) than the sedentary group (36±20%). Exercise time to the minimum calf muscle StO₂ was significantly different among groups, as both the LPA group (215±238 sec) and the MVPA group (377±351 sec) had greater values (p<0.05 and p<0.01, respectively) than the sedentary group (147±172 sec). Finally, high-sensitivity C-reactive protein was significantly different among groups, as both the LPA group (4.8±5.5 mg/L) and the MVPA group (3.5±3.6 mg/L) had lower values (p<0.01) than the sedentary group (8.6±8.4 mg/L).

CONCLUSIONS

Patients with claudication who reported performing LPA had greater amounts of objectively-determined physical activity levels and better physical function, HRQoL, and vascular measures than those who reported being physically sedentary. Furthermore, these favorable results associated with LPA were even more pronounced in patients who performed MVPA than in patients who were sedentary. The clinical significance is that engaging in any physical activity, even at relatively light intensity, is associated with favorable health and vascular measures in patients with claudication.

Association Between Daily Steps at Moderate Cadence and Vascular Outcomes in Patients With Claudication

PURPOSE

We determined whether patients with peripheral artery disease (PAD) and claudication grouped according to tertiles of community-based daily steps taken at a moderate cadence had differences in vascular function and biomarkers and whether group differences in vascular function and biomarkers persisted after adjusting for demographic variables, comorbid conditions, and severity of PAD.

METHODS

Two hundred sixty-three patients were evaluated for 1 wk on steps taken at a moderate cadence (exceeding 60 steps/min), and patients were placed into low (group 1), intermediate (group 2), and high (group 3) tertiles.

RESULTS

Ankle/brachial index (ABI) at 1 min after exercise (mean ± SD) was significantly higher in groups 2 and 3 than in group 1 in unadjusted (P < .01) and adjusted (P < .01) analyses (group 1: 0.34 ± 0.25; group 2: 0.38 ± 0.27; and group 3: 0.44 ± 0.28). Exercise time to reach the minimum calf muscle oxygen saturation (StO2) value during treadmill exercise was significantly longer in groups 2 and 3 than in group 1 in unadjusted (P < .01) and adjusted (P < .01) analyses (group 1: 127 ± 127 sec; group 2: 251 ± 266 sec; and group 3: 310 ± 323 sec). Fibrinogen was significantly lower in group 3 than in group 1 in unadjusted (P = .02) and adjusted (P = .05) analyses (group 1: 3.5 ± 1.2 g/L; group 2: 3.6 ± 1.5 g/L; and group 3: 3.0 ± 1.1 g/L).

CONCLUSIONS

Compared with patients with claudication in the lowest tertile of community-based daily steps taken at a moderate cadence, patients in the second and third tertiles had better calf muscle StO2 and ABI values during and immediately after exercise. Second, the most active group had lower fibrinogen levels than the least active group.

Comparison of Activity Monitors Accuracy in Assessing Intermittent Outdoor Walking

PURPOSE

This study aimed to determine and compare the accuracy of different activity monitors in assessing intermittent outdoor walking in both healthy and clinical populations through the development and validation of processing methodologies.

METHODS

In study 1, an automated algorithm was implemented and tested for the detection of short (≤1 min) walking and stopping bouts during prescribed walking protocols performed by healthy subjects in environments with low and high levels of obstruction. The following parameters obtained from activity monitors were tested, with different recording epochs0.1s/0.033s/1s/3s/10s and wearing locationsscapula/hip/wrist/ankle: GlobalSat DG100 (GS) and Qstarz BT-Q1000XT/-Q1000eX (QS) speed; ActiGraph wGT3X+ (AG) vector magnitude (VM) raw data, VM counts, and steps; and StepWatch3 (SW) steps. Furthermore, linear mixed models were developed to estimate walking speeds and distances from the monitors parameters. Study 2 validated the performance of the activity monitors and processing methodologies in a clinical population showing profile of intermittent walking due to functional limitations during outdoor walking sessions.

RESULTS

In study 1, GS1s, scapula, QS1s, scapula/wrist speed, and AG0.033s, hip VM raw data provided the highest bout detection rates (>96.7%) and the lowest root mean square errors in speed (≤0.4 km·h-1) and distance (<18 m) estimation. Using SW3s, ankle steps, the root mean square error for walking/stopping duration estimation reached 13.6 min using proprietary software and 0.98 min using our algorithm (total recording duration, 282 min). In study 2, using AG0.033s, hip VM raw data, the bout detection rate (95% confidence interval) reached 100% (99%-100%), and the mean (SD) absolute percentage errors in speed and distance estimation were 9% (6.6%) and 12.5% (7.9%), respectively.

CONCLUSIONS

GPS receivers and AG demonstrated high performance in assessing intermittent outdoor walking in both healthy and clinical populations.

Association between Physical Activity and Mortality in Patients with Claudication

PURPOSE

This study aimed to determine the association between light-intensity physical activity and the incidence of all-cause and cardiovascular mortality in patients with peripheral artery disease (PAD) limited by claudication followed for up to 18.7 yr.

METHODS

A total of 528 patients with PAD and claudication were screened in Baltimore between 1994 and 2002, and 386 were deemed eligible for the study. At baseline, patients were classified into three physical activity groups: 1) physically sedentary, 2) light intensity, and 3) moderate to vigorous intensity based on a questionnaire. All-cause and cardiovascular mortality of patients through December 2014 was determined using the National Death Index and the U.S. Department of Veterans Affairs and the U.S. Department of Defense Suicide Data Repository.

RESULTS

Median survival time was 9.9 yr (interquartile range, 4.9-15.7 yr; range, 0.38-18.7 yr). During follow-up, 257 patients (66.6%) died, consisting of 40/48 (83.3%) from the sedentary group, 135/210 (64.3%) from the light-intensity group, and 82/128 (64.0%) from the moderate- to vigorous-intensity group. For all-cause mortality, light-intensity activity status (hazard ratio [HR] = 0.523, P = 0.0007) and moderate- to vigorous-intensity status (HR = 0.425, P < 0.0001) were significant predictors. During follow-up, 125 patients died because of cardiovascular causes (32.4%), in which light-intensity activity status (HR = 0.511, P = 0.0113) and moderate- to vigorous-intensity activity status (HR = 0.341, P = 0.0003) were significant predictors.

CONCLUSIONS

Light-intensity physical activity is associated with nearly 50% lower risk of all-cause and cardiovascular mortality in high-risk patients with PAD and claudication. Furthermore, moderate- to vigorous-intensity physical activity performed regularly is associated with 58% and 66% lower risk of all-cause and cardiovascular mortality, respectively. The survival benefits associated with light-intensity physical activity make it a compelling behavioral intervention that extends beyond improving ambulation.

Effect of Home-based Exercise Therapy for Peripheral Arterial Disease Patients Underwent Endovascular Treatment: A Clinical Controlled Design

OBJECTIVE

This study aimed to clarify the effect of home-based exercise therapy on physical activity in peripheral arterial disease (PAD) patients after EVT.

METHODS

Study design was controlled clinical design. The subjects were 30 patients (76.6% men) who underwent EVT in the Sakakibara Heart Institute of Okayama. Patients with EVT meeting the inclusion criteria were divided into two groups, intervention group (Home-based exercise) and control group. Patients' basic characteristics, the number of steps walked and QOL questionnaire (WIQ, SEPA, Vascu QOL) were assessed before surgery and, at the 3 month after discharge. A two-way analysis of variance (ANOVA) was performed to compare number of steps walked and QOL questionnaire.

RESULTS

Interaction effect were observed in the number of steps walked (F (1,28) =13.89, p<0.01). A multiple comparison test confirmed a significant increase between results of before surgery and at three months after surgery in the intervention group (p<0.01). An interaction between the presence and absence of intervention was found for the WIQ pain score (F(1,28) = 5.86, p=0.01), speed score (F(1,28) = 3.80, p=0.04) and SEPA (F(1,28) = 4.99, p=0.03). In a multiple comparison study, there was a significant increase in WIQ pain and speed scores in both groups before and 3 months after discharge from the hospital.

CONCLUSION

Home-based exercise therapy using physical activity indices has the potential to improve number of steps and quality of life in patients with PAD after EVT.

Association between meeting daily step count goals with ambulatory function and quality of life in patients with claudication

OBJECTIVE

To determine (a) whether patients with peripheral artery disease (PAD) who walked at least 7000 and 10,000 steps/day had better ambulatory function and health-related quality of life (HRQoL) than patients who walked less than 7000 steps/day, and (b) whether differences in ambulatory function and HRQoL in patients grouped according to these daily step count criteria persisted after adjusting for covariates.

METHODS

Two hundred forty-eight patients were assessed on their daily ambulatory activity for 1 week with a step activity monitor, and were grouped according to daily step count targets. Patients who took fewer than 7000 steps/day were included in group 1 (n = 153), those who took 7000 to 9999 steps/day were included in group 2 (n = 57), and patients who took at least 10,000 steps/day were included in group 3 (n = 38). Primary outcomes were the 6-minute walk distance (6MWD) and Walking Impairment Questionnaire (WIQ) distance score, which is a disease-specific measurement of HRQoL. Patients were further characterized on demographic variables, comorbid conditions, and cardiovascular risk factors.

RESULTS

The groups were significantly different on ankle-brachial index (P = .02), and on the prevalence of hypertension (P = .04), diabetes (P < .01), abdominal obesity (P < .01), arthritis (P = .04), and chronic obstructive pulmonary disease (P < .01). Thus, these variables served as covariates in adjusted analyses, along with age, weight, and sex. The 6MWD (mean ± standard deviation) was significantly different among the groups in unadjusted (P < .01) and adjusted (P < .01) analyses (group 1, 313 ± 90 m; group 2, 378 ± 84 m; and group 3, 414 ± 77 m), with groups 2 and 3 having a higher 6MWD than group 1 (P < .01). The WIQ distance score was significantly different among the groups in unadjusted (P < .01) and adjusted (P < .01) analyses (group 1, 30 ± 30%; group 2, 45 ± 35%; and group 3, 47 ± 34%), with groups 2 and 3 having higher WIQ distance scores than group 1 (P < .01).

CONCLUSIONS

Patients with PAD who walked more than 7000 and 10,000 steps/day had greater ambulatory function and HRQoL than patients who walked fewer than 7000 steps/day. Second, the greater ambulatory function and HRQoL associated with walking 7000 and 10,000 steps/day persisted after adjusting for covariates. This study provides preliminary evidence that patients with PAD who walk more than 7000 steps/day have better ambulatory function and HRQoL than patients below this threshold.

Daily Step Counts in Participants With and Without Peripheral Artery Disease

PURPOSE

We compared the prevalence of participants with and without symptomatic peripheral artery disease (PAD) who met the goals of attaining >7000 and 10 000 steps/d, and we determined whether PAD status was significantly associated with meeting the daily step count goals before and after adjusting for demographic variables, comorbid conditions, and cardiovascular risk factors.

METHODS

Participants with PAD (n = 396) and without PAD (n = 396) were assessed on their walking for 7 consecutive days with a step activity monitor.

RESULTS

The PAD group took significantly fewer steps/d than the non-PAD control group (6722 ± 3393 vs. 9475 ± 4110 steps/d; P < .001). Only 37.6% and 15.7% of the PAD group attained the goals of walking >7000 and 10 000 steps/d, respectively, whereas 67.9% and 37.4% of the control group attained these goals (P < .001 for each goal). Having PAD was associated with a 62% lower chance of attaining 7000 steps/d than compared with the control group (OR = 0.383; 95% CI, 0.259-0.565; P < .001), and a 55% lower chance of attaining 10 000 steps/d (OR = 0.449; 95% CI, 0.282-0.709; P < .001). Significant covariates (P < .01) included age, current smoking, diabetes, and body mass index.

CONCLUSIONS

Participants with symptomatic PAD had a 29% lower daily step count compared with age- and sex-matched controls, and were less likely to attain the 7000 and 10 000 steps/d goals. Additionally, participants who were least likely to meet the 7000 and 10 000 daily step count recommendations included those who were older, currently smoked, had diabetes, and had higher body mass index.

Automated Detection of Exercise Sessions in Patients With Peripheral Artery Disease: EVIDENCE FOR AN EXERCISE DOSE RESPONSE TO TRAINING

PURPOSE

Monitoring home exercise using accelerometry in patients with peripheral artery disease (PAD) may provide a tool to improve adherence and titration of the exercise prescription. However, methods for unbiased analysis of accelerometer data are lacking. The aim of the current post hoc analysis was to develop an automated method to analyze accelerometry output collected during home-based exercise.

METHODS

Data were obtained from 54 patients with PAD enrolled in a clinical trial that included a home-based exercise intervention using diaries and an accelerometer. Peak walking time was assessed on a graded treadmill at baseline and 6 mo. In 35 randomly selected patient data sets, visual inspection of accelerometer output confirmed exercise sessions throughout the 6 mo. An algorithm was developed to detect exercise sessions and then compared with visual inspection of sessions to mitigate the heterogeneity in session intensity across the population. Identified exercise sessions were characterized on the basis of total step count and activity duration. The methodology was then applied to data sets for all 54 patients.

RESULTS

The ability of the algorithm to detect exercise sessions compared with visual inspection of the accelerometer output resulted in a sensitivity of 85% and specificity of 90%. Algorithm-detected exercise sessions (total) and intensity (steps/wk) were correlated with change in peak walking time (r = 0.28; r = 0.43).

CONCLUSIONS

An algorithm to assess data from an accelerometer successfully detected home-based exercise sessions. Algorithm-identified exercise sessions were correlated with improvements in performance after 6 mo of training in patients with PAD, supporting the effectiveness of monitored home-based exercise.

Differences in Physical Activity between Patients with Peripheral Artery Disease and Healthy Subjects

Objectives

Peripheral artery disease (PAD) is a significant prognostic marker of poor long-term survival due to limited physical activity associated with various functional problems, such as intermittent claudication. A physically active lifestyle has the potential to modify peripheral artery risk factors and promote general health. While low daily physical activity levels have been recognized in the population of PAD, the exact level has yet to be quantified due to lack of research. The aim of the present study was to compare physical activity level (PAL) and time spent at activities of different intensity levels between patients with PAD and healthy individuals. The study subjects were 10 patients with PAD and 10 age-matched healthy control subjects. We measured the time spent at light, moderate, or vigorous physical activity using triaxial accelerometer and calculated PAL. Intermittent claudication onset distance and maximum walking distance were defined as the distance walked at which the subject first reported leg pain and the distance at which the subject was unable to continue walking because of leg pain, respectively.

Results

Our results showed (i) lower PAL in patients with PAD compared with the controls; (ii) while there was no significant difference in the high-intensity activity between the two groups, the light- and moderate-intensity activities of the PAD group were significantly lower than the controls, the time spent at moderate-intensity activity was approximately 50% less; and (iii) among patients with PAD, low PAL did not correlate directly with intermittent claudication.

Conclusions

PAD patients limit the amount of their physical activity, especially light and moderate intensities. Our study highlights the importance of spending more time walking in daily life.

A randomized controlled trial of treatment with intermittent negative pressure for intermittent claudication

OBJECTIVE

We investigated the effects of lower extremity intermittent negative pressure (INP) treatment for 1 hour two times daily for 12 weeks on the walking distance of patients with intermittent claudication (IC).

METHODS

Patients with IC were randomized to treatment with -40 mm Hg INP (treatment group) or -10 mm Hg INP (sham control group). Pain-free walking distance (PWD) and maximal walking distance (MWD) on a treadmill, resting and postexercise ankle-brachial index, resting and postischemic blood flow (plethysmography), and quality of life (EQ-5D-5L and Vascuqol-6) were measured at baseline and after 12 weeks of treatment.

RESULTS

A total of 72 patients were randomized, and 63 had data available for the intention-to-treat analyses. The between-group comparisons showed a significant change in the PWD, favoring the treatment group over the sham control group (estimated treatment effect, 50 m; 95% confidence interval [CI], 11-89; P = .014). The PWD had increased by 68 m (P < .001) in the treatment group and 18 m (P = .064) in the sham control group. No significant difference was found in the change in the MWD between the two groups (estimated treatment effect, 42 m; 95% CI, -14 to 97; P = .139). The MWD had increased by 62 m (P = .006) in the treatment group and 20 m (P = .265) in the sham control group. For patients with a baseline PWD of <200 m (n = 56), significant changes had occurred in both PWD and MWD between the two groups, favoring the treatment group (estimated treatment effect, 42 m; 95% CI, 2-83; P = .042; and estimated treatment effect, 62 m; 95% CI, 5-118; P = .032; respectively). Both overall and for the group of patients with a PWD <200 m, no significant differences were found in the changes in the resting and postexercise ankle-brachial index, resting and postischemic blood flow, or quality of life parameters between the two groups.

CONCLUSIONS

Treatment with -40 mm Hg INP increased the PWD compared with sham treatment in patients with IC. For the patients with a baseline PWD of <200 m, an increase was found in both PWD and MWD compared with sham treatment.

Accuracy of Thresholds Based on Cadence and Lifestyle Counts per Minute to Detect Outdoor Walking in Older Adults With Mobility Limitations

OBJECTIVE

To determine the optimal threshold, based on cadence and lifestyle counts per minute, to detect outdoor walking in mobility-limited older adults.

METHODS

Older adults (N = 25, median age: 77.0 years, interquartile range: 10.5) wore activity monitors during 80 outdoor walks. Walking bouts were identified manually (reference standard) and compared with identification using cadence thresholds (≥30, ≥35, ≥40, ≥45, and ≥50 steps/min) and >760 counts per minute using low frequency extension analysis.

RESULTS

Median walking bout duration was 10.5 min (interquartile range 4.8) and median outdoor walking speed was 0.70 m/s (interquartile range 0.20). Cadence thresholds of ≥30, ≥35, and ≥40 steps/min demonstrated high sensitivity (1.0, 95% confidence intervals [0.95, 1.0]) to detect walking bouts; estimates for specificity and positive predictive value were highest for ≥40 steps/min.

CONCLUSION

A cadence threshold of ≥40 steps/min is recommended for detecting sustained outdoor walking in this population.

Association between calf muscle oxygen saturation with ambulatory function and quality of life in symptomatic patients with peripheral artery disease

OBJECTIVE

The objective of this study was to determine whether calf muscle hemoglobin oxygen saturation (Sto₂) obtained during a standardized treadmill test is associated with ambulatory function and health-related quality of life (HRQoL) in patients with symptomatic peripheral artery disease (PAD). We hypothesized that a rapid decline in calf muscle Sto₂ during walking is associated with impaired ambulatory function and HRQoL and that these associations are independent of ankle-brachial index (ABI).

METHODS

Calf muscle Sto₂, peak walking time, and claudication onset time were obtained during a treadmill test in 151 symptomatic men and women with PAD. Patients were further characterized by demographic variables, comorbid conditions, cardiovascular risk factors, ABI, 6-minute walk distance, daily ambulatory activity, Walking Impairment Questionnaire (WIQ) score, and Medical Outcomes Study 36-Item Short Form Health Survey physical function score to assess HRQoL.

RESULTS

The median calf muscle Sto₂ value at rest was 52%, which declined to 22% after only 1 minute of walking during the treadmill test and reached a minimum value of 9% after a median time of 87 seconds of walking. Of the various calf muscle Sto₂ measurements obtained during the treadmill test, the exercise time to the minimum calf muscle Sto₂ value (log transformed) had the strongest univariate associations with peak walking time (r = 0.56; P < .001), claudication onset time (r = 0.49; P < .001), 6-minute walk distance (r = 0.31; P < .001), WIQ distance score (r = 0.33; P < .001), WIQ speed score (r = 0.39; P < .001), WIQ stair-climbing score (r = 0.37; P < .001), and Medical Outcomes Study 36-Item Short Form Health Survey physical function score (r = 0.32; P < .001). In adjusted multiple regression models, these associations persisted (P < .001) after adjustment for demographic measures, cardiovascular risk factors, comorbid conditions, and ABI.

CONCLUSIONS

More rapid decline in oxygen saturation of the calf musculature during walking, indicative of impaired microcirculation, is predictive of impaired ambulatory function and HRQoL in patients with symptomatic PAD. Of particular importance, these associations are independent of ABI and other common health burdens, highlighting the clinical relevance that the microcirculation has on ambulatory function and HRQoL in patients with symptomatic PAD.

Effects of Intermittent Calf Muscle Electrical Stimulation on Walking Capacity in Claudicants Living with Type 2 Diabetes

BACKGROUND

First-line therapy for diabetic patients presenting with intermittent claudication includes supervised exercise programs to improve walking distance. However, exercise comes with a variety of barriers and may be contraindicated in certain conditions. The aim of this study was to evaluate whether calf muscle electrostimulation improves claudication distance.

METHODS

A prospective, one-group, pretest-posttest study design was used on 40 participants living with type 2 diabetes mellitus, peripheral artery disease (ankle brachial pressure index, <0.90), and calf muscle claudication. Calf muscle electrostimulation of varying frequencies (1-250 Hz) was prescribed on both limbs for 1-hour daily sessions for 12 consecutive weeks. The absolute claudication distance (ACD) was measured at baseline and after the intervention.

RESULTS

The recruited cohort (30 men and ten women; mean age, 71 years; mean ankle brachial pressure index, 0.70) registered a mean ± SD baseline ACD of 333.71 ± 208 m. After a mean ± SD of 91.68 ± 6.23 days of electrical stimulation, a significant mean ± SD increase of 137 ± 136 m in the ACD (P = .001, Wilcoxon signed rank test) was registered. Improvement was found to be sex independent, but age was negatively correlated with proportion of improvement (r = -0.361; P = .011, Pearson correlation test).

CONCLUSIONS

Electrical stimulation of varying frequencies on ischemic calf muscles significantly increased the maximal walking capacity in claudicants with type 2 diabetes. This therapeutic approach should be considered in patients with impaired exercise tolerance or as an adjunct treatment modality.

Altered Metabolomic Profile in Patients with Peripheral Artery Disease

Peripheral artery disease (PAD) is a common atherosclerotic disease characterized by narrowed or blocked arteries in the lower extremities. Circulating serum biomarkers can provide significant insight regarding the disease progression. Here, we explore the metabolomics signatures associated with different stages of PAD and investigate potential mechanisms of the disease. We compared the serum metabolites of a cohort of 26 PAD patients presenting with claudication and 26 PAD patients presenting with critical limb ischemia (CLI) to those of 26 non-PAD controls. A difference between the metabolite profiles of PAD patients from non-PAD controls was observed for several amino acids, acylcarnitines, ceramides, and cholesteryl esters. Furthermore, our data demonstrate that patients with CLI possess an altered metabolomic signature different from that of both claudicants and non-PAD controls. These findings provide new insight into the pathophysiology of PAD and may help develop future diagnostic procedures and therapies for PAD patients.

Normative Peak 30-Min Cadence (Steps per Minute) Values for Older Adults: NHANES 2005-2006

Walking cadence (steps per minute) is associated with the intensity of ambulatory behavior. This analysis provides normative values for peak 30-min cadence, an indicator of "natural best effort" during free-living behavior. A sample of 1,196 older adults (aged from 60 to 85+) with accelerometer data from the National Health and Nutrition Examination Survey 2005-2006 was used. Peak 30-min cadence was calculated for each individual. Quintile-defined values were computed, stratified by sex and age groups. Smoothed sex-specific centile curves across the age span were fitted using the LMS method. Peak 30-min cadence generally trended lower as age increased. The uppermost quintile value was >85 steps/min (men: 60-64 years), and the lowermost quintile value was <22 steps/min (women: 85+). The highest 95th centile value was 103 steps/min (men: 64-70 years), and the lowest 5th centile value was 15 steps/min (women: 85+). These normative values may be useful for evaluating older adults' "natural best effort" during free-living ambulatory behavior.

Changes in Intensity and Duration of Walking among Older Adults from In-Patient Geriatric Rehabilitation to Home

Purpose: We compared walking in hospital and on discharge from in-patient geriatric rehabilitation. Method: Participants included 28 adults (22 women) with a mean age of 85.4 (SD 6.8) years, ambulating independently with planned discharge to the community. Steps per day, short and long walking bouts, and cadence (steps per minute) were measured using an ActiGraph GT3X+ activity monitor (5 d in hospital, 5 d at home). Results: Steps per day did not differ between hospital and home (median difference=401; 95% CI: -364, 1,215; p=0.10). Long walking bouts (≥5 min) were infrequent in both locations (1/d) but lasted longer in hospital. Short walking bouts (≥15 s) were more frequent and shorter at home. Daily peak 1-minute cadence and peak 30-minute cadence were greater in hospital. Conclusions: Older adults in geriatric rehabilitation take longer walks and walk at faster paces in hospital, and they engage in more frequent, shorter walks at home. Although further research is needed, older adults would benefit from the opportunity to walk at different paces and different distances on discharge. Outpatient rehabilitation or other community-based programmes and initiatives may provide these experiences and appropriate environments to enable individuals to maintain mobility and independent functioning in the long term.

Leg blood flow and skeletal muscle microvascular perfusion responses to submaximal exercise in peripheral arterial disease

Peripheral arterial disease (PAD) is characterized by stenosis and occlusion of the lower limb arteries. Although leg blood flow is limited in PAD, it remains unclear whether skeletal muscle microvascular perfusion is affected. We compared whole leg blood flow and calf muscle microvascular perfusion after cuff occlusion and submaximal leg exercise between patients with PAD ( n = 12, 69 ± 9 yr) and healthy age-matched control participants ( n = 12, 68 ± 7 yr). Microvascular blood flow (microvascular volume × flow velocity) of the medial gastrocnemius muscle was measured before and immediately after the following: 1) 5 min of thigh-cuff occlusion, and 2) a 5-min bout of intermittent isometric plantar-flexion exercise (400 N) using real-time contrast-enhanced ultrasound. Whole leg blood flow was measured after thigh-cuff occlusion and during submaximal plantar-flexion exercise using strain-gauge plethysmography. Postocclusion whole leg blood flow and calf muscle microvascular perfusion were lower in patients with PAD than control participants, and these parameters were strongly correlated ( r = 0.84, P < 0.01). During submaximal exercise, total whole leg blood flow and vascular conductance were not different between groups. There were also no group differences in postexercise calf muscle microvascular perfusion, although microvascular blood volume was higher in patients with PAD than control participants (12.41 ± 6.98 vs. 6.34 ± 4.98 arbitrary units, P = 0.03). This study demonstrates that the impaired muscle perfusion of patients with PAD during postocclusion hyperemia is strongly correlated with disease severity and is likely mainly determined by the limited conduit artery flow. In response to submaximal leg exercise, microvascular flow volume was elevated in patients with PAD, which may reflect a compensatory mechanism to maintain muscle perfusion and oxygen delivery during recovery from exercise.

NEW & NOTEWORTHY This study suggests that peripheral arterial disease (PAD) has different effects on the microvascular perfusion responses to cuff occlusion and submaximal leg exercise. Patients with PAD have impaired microvascular perfusion after cuff occlusion, similar to that previously reported after maximal exercise. In response to submaximal exercise, however, the microvascular flow volume response was elevated in patients with PAD compared with control. This finding may reflect a compensatory mechanism to maintain perfusion and oxygen delivery during recovery from exercise.

Predictors of health-related quality of life in patients with symptomatic peripheral artery disease

OBJECTIVE

The aim of this study was to identify predictors of baseline measures of health-related quality of life (HRQoL) in symptomatic patients with peripheral artery disease (PAD) from objective markers of severity of PAD, clinical and demographic characteristics, comorbid conditions, cardiovascular risk factors, objectively measured physical activity, and patient-based measures of physical function.

METHODS

HRQoL measurements of 216 symptomatic men and women with PAD were assessed with the Medical Outcomes Study 36-Item Short Form Health Survey. Patients were further characterized on demographic variables, comorbid conditions, cardiovascular risk factors, ankle-brachial index, peak walking time during a maximal treadmill test, 6-minute walk distance, gait speed, ambulatory activity monitored during 1 week, activities of daily living (ADLs), Mini-Mental State Examination questionnaire, and Walking Impairment Questionnaire (WIQ).

RESULTS

For the physical function HRQoL subscale, the significant predictors included WIQ speed score (P < .001), history of stumbling (P < .001), WIQ stair climbing score (P < .001), ADL associated with bathing (P = .001), 6-minute walk distance (P = .004), and daily walking cadence (P = .043). For the role emotional function HRQoL subscale, the significant predictors included a history of stumbling (P < .001), the ADL associated with transferring from a bed to a chair (P < .001), and the WIQ distance score (P = .022).

CONCLUSIONS

Physical and mental subscales of HRQoL in symptomatic patients with PAD are primarily predicted by patient-based physical function rather than by more specific markers of PAD severity and comorbid conditions. The clinical significance is that interventions designed to improve HRQoL should focus on improving the quality of executing functional tasks, such as walking more steadily without stumbling; completing ADLs that are not specific to walking, such as bathing and transferring; and improving patient-based ability to walk various distances and speeds and to climb stairs.

Quantification of Daily Physical Activity and Sedentary Behavior of Claudicating Patients

BACKGROUND

Claudication is the most common manifestation of peripheral artery disease (PAD), producing significant ambulatory compromise. Limited information exists on the routine physical activity of claudicating patients. Our objective was to record the intensity/time profiles of physical activity and the timing and duration of sedentary behavior of a sample of community-dwelling claudicating patients.

METHODS

Forty-four claudicating patients referred to our vascular clinic were recruited. Physical activity was recorded using the ActiGraph GT1M activity monitor. The Actigraph monitor is a lightweight instrument designed to measure human movement through changes in acceleration, measured as counts over 1-minute time periods. Data from 7 consecutive days were used for the calculations. We processed the data using the ActiLife software program.

RESULTS

The average daily activity of the claudicating patients shows a steady increase beginning approximately 05:30 AM until a peak plateau from approximately 10:00 AM to 01:30 PM followed by a steady decrease until approximately 09:30 PM, when a sustained period of inactivity begins. The average claudicating patient takes 3586 steps per day at an average intensity of 1.77 metabolic equivalents of task (METs, a physiological measure expressing the energy cost of physical activities). Average physical activity intensity and peak intensity fluctuate very little during the day, and they rarely exceed the level of light activity (light = <3 METs maximum effort, such as casual walking or light housework). During awake time, approximately 7 hours are spent in sedentary behaviors (<1.5 METs), and sedentary time is spread throughout the day mostly in short intervals between periods of low-energy activity.

CONCLUSIONS

Our study objectively demonstrates the reduced physical activity of claudicating patients and documents physical activity/duration profiles throughout the day. The intensity of the physical activity of the average claudicating patient fluctuates very little during the day and rarely exceeds a light intensity level. Claudicating patients spend approximately half of their awake time in sedentary behavior and when they walk they do it in short bursts followed by several minutes of rest. We anticipate that changes in routine physical activity/duration profiles of patients with PAD will provide relevant, sensitive, and direct measures of the effectiveness of therapeutic interventions.

Gait Mechanics Differences Between Healthy Controls and Patients With Peripheral Artery Disease After Adjusting for Gait Velocity Stride Length and Step Width

Patients with peripheral artery disease (PAD) experience significant leg dysfunction. The effects of PAD on gait include shortened steps, slower walking velocity, and altered gait kinematics and kinetics, which may confound joint torques and power measurements.

Spatiotemporal parameters, joint torques and powers were calculated and compared between 20 patients with PAD and 20 healthy controls using independent t-tests. Separate ANCOVA models were used to evaluate group differences after independently adjusting for gait velocity, stride length and step width. Compared to healthy controls, patients with PAD exhibited reduced peak extensor and flexor torques at the knee, and hip. After adjusting for all covariates combined, differences between groups remained for ankle power generation in late stance, and knee flexor torque. Reduced walking velocity observed in subjects affected by PAD was closely connected with reductions in joint torques and powers during gait. Gait differences remained, at the knee and ankle, after adjusting for the combined effect of spatiotemporal parameters. Improving muscle function through exercise or with the use of assistive devices needs to be a key tool in the development of interventions that aim to enhance the ability of PAD patients to restore spatiotemporal gait parameters.

How fast is fast enough? Walking cadence (steps/min) as a practical estimate of intensity in adults: a narrative review

Background

Cadence (steps/min) may be a reasonable proxy-indicator of ambulatory intensity. A summary of current evidence is needed for cadence-based metrics supporting benchmark (standard or point of reference) and threshold (minimums associated with desired outcomes) values that are informed by a systematic process.

Objective

To review how fast, in terms of cadence, is enough, with reference to crafting public health recommendations in adults.

Methods

A comprehensive search strategy was conducted to identify relevant studies focused on walking cadence and intensity for adults. Identified studies (n=38) included controlled (n=11), free-living observational (n=18) and intervention (n=9) designs.

Results

There was a strong relationship between cadence (as measured by direct observation and objective assessments) and intensity (indirect calorimetry). Despite acknowledged interindividual variability, ≥100 steps/min is a consistent heuristic (e.g, evidence-based, rounded) value associated with absolutely defined moderate intensity (3 metabolic equivalents (METs)). Epidemiological studies report notably low mean daily cadences (ie, 7.7 steps/min), shaped primarily by the very large proportion of time (13.5 hours/day) spent between zero and purposeful cadences (<60 steps/min) at the population level. Published values for peak 1-min and 30-min cadences in healthy free-living adults are >100 and >70 steps/min, respectively. Peak cadence indicators are negatively associated with increased age and body mass index. Identified intervention studies used cadence to either prescribe and/or quantify ambulatory intensity but the evidence is best described as preliminary.

Conclusions

A cadence value of ≥100 steps/min in adults appears to be a consistent and reasonable heuristic answer to ’How fast is fast enough?' during sustained and rhythmic ambulatory behaviour.

Trial registration number

NCT02650258

The PodPAD project: a podiatry-led integrated pathway for people with peripheral arterial disease in the UK - a pilot study

Background

Peripheral arterial disease affects the lower limb and is associated with diabetes, high cholesterol, smoking and obesity. It increases the risk of cardiovascular morbidity and mortality. It can be symptomatic causing intermittent claudication, but often there are few clinical signs. Podiatrists are able to detect the presence of peripheral arterial disease as part of their lower limb assessment and are well placed to give advice on lifestyle changes to help reduce disease progression. This is important to improve health outcomes and is offered as a prevention/public health intervention.

Method

We describe the clinical and patient-centred outcomes of patients attending a podiatry-led integrated care pathway in a multi-use clinic situated in a venue supported by the National Centre for Sports and Exercise Medicine in the UK. At the baseline appointment, patients were given a full assessment where symptoms of intermittent claudication using the Edinburgh Intermittent Claudication Questionnaire, foot pulses, Doppler sounds, Ankle Brachial Pressure Indices, glycated haemoglobin (HbA1c) and cholesterol levels, and smoking status were recorded. A tailored treatment plan was devised, including referral to an exercise referral service, smoking cessation programmes (if applicable) and each participant was also seen by a dietician for nutritional advice. Participants were followed up at 3 and 6 months to assess any improvement in vascular status and with each completing the EQ-5D quality of life questionnaire and a simple satisfaction questionnaire at the end of the study. As this was a complex intervention a pilot study design was adopted to evaluate if the method and outcomes were suitable and acceptable to participants the results of which will then inform the design of a larger study.

Results

Data was collected on 21 individuals; 15 men (71.4%) and 6 women (28.6%) across the 6-month study period. Eleven participants were referred onto the exercise referral service; 16 participants saw the dietician for nutritional advice at baseline and had one-to-one or telephone follow-up at 3 months. Five out of 14 participants had reduced scores from baseline of intermittent claudication during the study period. No evidence for substantive changes in Doppler sounds or ABPI measurements was revealed. Quality of life scores with the EQ-5D improved in 15 participants; this was statistically significant (p = 0.007) with 14 participants who completed the simple satisfaction questionnaire expressing a positive view of the programme. Of the four people who were smokers, two stopped smoking cigarettes and moved to e-cigarettes as part of smoking cessation advice.

Conclusion

As this was a pilot study the sample size was low, but some statistically significant improvements with some measures were observed over the 6-month study. Podiatrists are able to provide a comprehensive vascular assessment of the lower limb and accompanying tailored advice on lifestyle changes including smoking cessation and exercise. Locating clinics in National Centres for Sports and Exercise Medicine enables easy access to exercise facilities to encourage the adoption of increased activity levels, though the long term sustainability of exercise programmes still requires evaluation.This study was reviewed and approved by London Brent Ethics Committee IRAS ID 204611 and received research governance approval from the sponsor, Sheffield Teaching Hospitals NHS Foundation Trust Research and Innovation Office STH19410.

Abdominal obesity adversely affects bone mass in children

AIM

To determine the effect of childhood obesity and insulin resistance on bone health.

METHODS

We conducted a cross sectional study in pubertal adolescents and young adults 13-20 years old who were either overweight/obese or normal weight. Participants were Tanner 3 or above for pubertal stage, and had fasting blood work done to measure glucose, insulin, C-reactive protein and lipid levels. Homeostatic model of insulin resistance (HOMA-IR) was calculated using the formula (Fasting Blood Glucose *Insulin/405). Body composition and bone mineral density were measured using dual energy X-ray absorptiometry (DXA; Hologic QDR 4500, Waltham, MA, United Kingdom).

RESULTS

Percent trunk fat was associated inversely with whole body bone mineral content (BMC), whereas HOMA-IR was associated positively with whole body BMC.

CONCLUSION

Our results suggest that abdominal adiposity may have an adverse effect on whole body bone parameters and that this effect is not mediated by insulin resistance.

Sedentary Behavior, Cadence, and Physical Activity Outcomes after Knee Arthroplasty

PURPOSE

This study comprehensively examined sedentary behavior and physical activity patterns in people with severe knee osteoarthritis awaiting total knee arthroplasty (TKA) and in individuals after TKA.

METHODS

Preoperative (n = 32, mean ± SD = 69.9 ± 5.3 yr) and 1-yr postoperative participants with TKA (n = 38, 67.9 ± 7.3 yr) wore ActiGraph GT3X+ activity monitors for 6.8 ± 0.6 d. Total sedentary time, time in long sedentary bouts (≥30 min), and physical activity outcomes (steps, time in moderate-to-vigorous physical activity [MVPA], cadence) were examined.

RESULTS

There were no differences between pre- and postoperative groups for total sedentary time (9.3 ± 1.4 vs 9.2 ± 1.4 h·d, P = 0.62) and number of long sedentary bouts per day (median [interquartile range] = 3.4 [1.9] vs 3.1 [2.0], P = 0.37). Daily steps, peak 30-min cadence, and peak 1-min cadence values were greater in people after TKA compared with those awaiting surgery (5935 [3316] vs 3724 [2338], 55.6 [31.0] vs 35.9 [19.3], and 91.5 ± 20.6 vs 70.0 ± 23.7, respectively, all P < 0.01). There were no differences in lifestyle MVPA between groups. The number of bouts of Freedson MVPA was greater in postoperative participants, but the differences were not substantial (one bout per week).

CONCLUSION

Patients report less knee pain and improved function after TKA; however, sedentary behavior does not differ and physical activity is only marginally increased compared with those awaiting surgery. After TKA, daily walking at slow, moderate, and brisk paces and engagement in MVPA do not match levels seen in healthy older adults, which, when combined with high levels of sedentary behavior, leaves patients at increased risk for physical disability and cardiovascular disease.

Baroreflex and neurovascular responses to skeletal muscle mechanoreflex activation in humans: an exercise in integrative physiology

Cardiovascular adjustments to exercise resulting in increased blood pressure (BP) and heart rate (HR) occur in response to activation of several neural mechanisms: the exercise pressor reflex, central command, and the arterial baroreflex. Neural inputs from these feedback and feedforward mechanisms integrate in the cardiovascular control centers in the brain stem and modulate sympathetic and parasympathetic neural outflow, resulting in the increased BP and HR observed during exercise. Another specific consequence of the central neural integration of these inputs during exercise is increased sympathetic neural outflow directed to the kidneys, causing renal vasoconstriction, a key reflex mechanism involved in blood flow redistribution during increased skeletal muscle work. Studies in humans have shown that muscle mechanoreflex activation inhibits cardiac vagal outflow, decreasing the sensitivity of baroreflex control of HR. Metabolite sensitization of muscle mechanoreceptors can lead to reduced sensitivity of baroreflex control of HR, with thromboxane being one of the metabolites involved, via greater inhibition of cardiac vagal outflow without affecting baroreflex control of BP or baroreflex resetting. Muscle mechanoreflex activation appears to play a predominant role in causing renal vasoconstriction, both in isolation and in the presence of local metabolites. Limited investigations in older adults and patients with cardiovascular-related disease have provided some insight into how the influence of muscle mechanoreflex activation on baroreflex function and renal vasoconstriction is altered in these populations. However, future research is warranted to better elucidate the specific effect of muscle mechanoreflex activation on baroreflex and neurovascular responses with aging and cardiovascular-related disease.

Prediction of 6-minute walk performance in patients with peripheral artery disease

BACKGROUND

Peripheral artery disease (PAD) is a highly prevalent disease that impairs walking ability. Walking tests, such as the 6-minute walk test (6MWT) and 4-meter walk test, are commonly used to assess exercise endurance and ambulatory function over a short distance, respectively. The 6MWT performance is predictive of PAD severity and disease outcomes, but it is not feasible in many clinical settings because it requires a long walkway to serve as the test route and lengthens clinic visits. As an alternative, the 4-meter walk test is convenient, inexpensive, and repeatable, but whether it accurately predicts endurance performance in the long-distance 6MWT is not known. The goal of this study was to develop a statistical model to predict 6MWT gait speed from 4-meter walk test results and clinical characteristics among patients with PAD.

METHODS

Measures of 6MWT gait speed were derived from 183 patients with symptomatic PAD who were evaluated at the University of Oklahoma Health Sciences Center (2004-2012). The testing procedures and research personnel remained constant throughout the duration of the study. Independent variables included demographic and clinical information and 4-meter walk test gait speed. Fivefold cross validation and manual backward selection were used for model selection. Adjusted R² and corrected Akaike information criterion were applied to quantify the predictive performance of the regression models.

RESULTS

A total of 183 people (54% male; mean age, 65 [standard deviation (SD), 10] years) with moderate PAD severity (ankle-brachial index [ABI]; mean, 0.72 [SD, 0.24]) performed the walking tests. Participants covered an average distance of 335 (SD, 97) m distance in the 6MWT. The 4-meter walk gait speed, ABI, and dyspnea were independent predictors of 6MWT speed in the multivariate model (adjusted R² = 0.55). The model resulted in 95% prediction interval widths of 30 m for mean and 260 m for individual predicted 6MWT distance measures.

CONCLUSIONS

Slower 4-meter walking speed, lower ABI, and presence of dyspnea all predict slower 6MWT gait speed, which corresponds to shorter 6MWT distance. Prediction of group means is reasonably precise; however, prediction of individual patient 6MWT performance is imprecise relative to between-group differences that are clinically important.

Muscle mechanoreflex activation via passive calf stretch causes renal vasoconstriction in healthy humans

Reflex renal vasoconstriction occurs during exercise, and renal vasoconstriction in response to upper-limb muscle mechanoreflex activation has been documented. However, the renal vasoconstrictor response to muscle mechanoreflex activation originating from lower limbs, with and without local metabolite accumulation, has not been assessed. Eleven healthy young subjects (26 ± 1 yr; 5 men) underwent two trials involving 3-min passive calf muscle stretch (mechanoreflex) during 7.5-min lower-limb circulatory occlusion (CO). In one trial, 1.5-min 70% maximal voluntary contraction isometric calf exercise preceded CO to accumulate metabolites during CO and stretch (mechanoreflex and metaboreflex; 70% trial). A control trial involved no exercise before CO (mechanoreflex alone; 0% trial). Beat-to-beat renal blood flow velocity (RBFV; Doppler ultrasound), mean arterial blood pressure (MAP; photoplethysmographic finger cuff), and heart rate (electrocardiogram) were recorded. Renal vascular resistance (RVR), an index of renal vasoconstriction, was calculated as MAP/RBFV. All baseline cardiovascular variables were similar between trials. Stretch increased RVR and decreased RBFV in both trials (change from CO with stretch: RVR - 0% trial = Δ 10 ± 2%, 70% trial = Δ 7 ± 3%; RBFV - 0% trial = Δ -3.8 ± 1.1 cm/s, 70% trial = Δ -2.7 ± 1.5 cm/s; P < 0.05 for RVR and RBFV). These stretch-induced changes were of similar magnitudes in both trials, e.g., with and without local metabolite accumulation, as well as when thromboxane production was inhibited. These findings suggest that muscle mechanoreflex activation via passive calf stretch causes renal vasoconstriction, with and without muscle metaboreflex activation, in healthy humans.

Association between daily walking and antioxidant capacity in patients with symptomatic peripheral artery disease

OBJECTIVE

The primary aim of the study was to assess whether both the amount and pace of daily walking were associated with circulating antioxidant capacity in symptomatic patients with peripheral artery disease (PAD).

METHODS

Community-based walking was measured in 244 men and women who were limited by symptomatic PAD during a 1-week period in which they wore an ankle-mounted step activity monitor. Patients were further characterized by circulating antioxidant capacity with the OxiSelect (Cell Biolabs Inc, San Diego, Calif) hydroxyl radical antioxidant capacity (HORAC) activity assay.

RESULTS

To assess the amount of walking, patients were grouped into low (≤2440 strides/d), middle (2441-3835 strides/d), and high (>3835 strides/d) stride tertiles. HORAC was higher in the middle (P = .03) and high (P = .01) stride tertiles than in the low tertile, but there was no difference between middle and high tertiles (P = .44). To assess the pace of walking, patients were grouped into slow (<25.0 strides/min), middle (25.0-31.6 strides/min), and fast (>31.6 strides/min) cadence tertiles. HORAC was higher in the high cadence tertile than in the low (P < .01) and middle (P < .01) tertiles, but there was no difference between low and middle tertiles (P = .48). Similar findings were obtained on group differences in HORAC after adjusting for age, sex, race, and ankle-brachial index for both the amount and pace of daily walking.

CONCLUSIONS

Walking >2440 strides each day and walking at a cadence faster than 31.6 strides/min for 30 minutes each day are both associated with greater circulating antioxidant capacity in symptomatic patients with PAD. The clinical significance is that a home-based walking program may be one approach to increase endogenous antioxidant capacity.

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.

Clinical importance of change in physical activity after endovascular treatment combined with exercise training in patients with peripheral arterial disease

We aimed to investigate the characteristics of changes in amount of physical activity of patients with peripheral arterial disease (PAD) before/after endovascular treatment (EVT) combined with exercise training. Twenty-two patients with peripheral arterial disease at stage-II of the Fontaine classification who received EVT combined with exercise training were included in this study. A tri-axial accelerometer was used to record physical activity every day from the day before surgery to 3 months after discharge from hospital. The mean number of walking steps before surgery was 2664 steps (611 steps-5404 steps), whereas those after surgery was 3393 (567 steps-7578 steps). Ankle Brachial Index (from 0.69 to 1.03; p < 0.001), maximum walking distance (from 728.2 to 1271.8 m; p < 0.05) and Vascu-QOL (from 98.9 to 137.9; p < 0.01) showed improvement between before and after surgery. Physical activity of patients with PAD was still low at 3 months after surgery even though walking ability, QOL, and self-efficacy were improved after EVT combined with exercise training. Among the 22 patients, the number of walking steps increased in 17 of them and decreased in 5 of them. Compared with the patients in the increased-steps group, those in the decreased-steps group were significantly older (p < 0.05), and had a significantly higher cardiovascular event rate within the first 3 months after surgery (p < 0.05). These results suggested that, not only the improvement of walking ability, but increase in physical activity after EVT combined with exercise training is also important for short-term prognosis.

Functional level assessment of individuals with transtibial limb loss: Evaluation in the clinical setting versus objective community ambulatory activity

The functional level (K level) of prosthetic users is used to choose appropriate prosthetic components, but ratings may highly subjective. A more objective and robust method to determine K level may be appealing. The aim of this study was to determine the relationship between K level determined in the clinic to K level based on real world ambulatory activity data collected by StepWatch. Twelve individuals with transtibial limb loss gave informed consent to participate. K level assessments performed in the clinic by a single treating prosthetist were compared with a calculated estimate based on seven days of real world ambulatory activity patterns using linear regression. There was good agreement between the two methods of determining K level with R²= 0.775 (p < 0.001). The calculated estimate of K level based on actual ambulatory activity in real world settings appears to be similar to the treating prosthetist’s assessment of K level based on gait observation and patient responses in the clinic. Clinic-based ambulatory capacity in transtibial prosthetic users appears to correlate with real world ambulatory behavior in this small cohort. Determining functional level based on real world ambulatory activity may supplement clinic-based tests of functional capacity.