Quantification of Daily Physical Activity and Sedentary Behavior of Claudicating Patients

A scoping review of postoperative early rehabilitation programs after dysvascular-related amputations

BACKGROUND

After amputation, people face challenges including wound healing and decreased functional mobility. Early mobilization in acute hospital care has proved safe, improved function, and sped discharge. Still, loss of a leg complicates standing and early mobilization after amputation. Approaches to early mobilization and rehabilitation after amputation surgery have not been widely studied.

OBJECTIVES

To map the evidence regarding early postoperative mobilization after dysvascular amputation. Specific aims included identifying research designs and populations, describing rehabilitation approaches, and identifying gaps within the literature.

STUDY DESIGN

Scoping review following PRISMA-Sc guidelines.

METHODS

The a priori scoping review methodology conducted in June 2022 with English language and 20-year limits used the OVID Medline, OVID Allied and Complementary Medicine Database, Cumulative Index to Nursing and Allied Health Literature, Cochrane databases, and Journal of Prosthetics and Orthotics archive. Reviewer pairs used Covidence software to screen for inclusion (subjects with major lower limb dysvascular amputations, seen immediately postoperatively for hospital-based rehabilitation) with decisions by concurrence. Data for best practice scoping reviews were synthesized for analysis.

RESULTS

Two hundred ninety-six citations were screened, 13 full texts reviewed, and 8 articles included: 2 cohort studies, 3 case-control studies, 2 single-group interventional studies, and 1 case study. There were no randomized control trials or prospective comparison group trials.

CONCLUSIONS

Few studies were identified regarding acute rehabilitation after major lower extremity amputation. The limited evidence in this review suggested that early mobilization in the days after amputation was safe with or without use of temporary prostheses, although further research is certainly warranted.

Sarcopenia is associated with lower step count in patients with peripheral artery disease following endovascular treatment

INTRODUCTION

Patients with peripheral artery disease (PAD) often complain of reduced physical activity (PA) despite improvements in intermittent claudication after successful endovascular treatment (EVT). Sarcopenia resulting from chronic ischemia can affect post-EVT PA levels.

OBJECTIVE

This study aims to assess the association between sarcopenia and post-EVT PA levels.

METHODS

One hundred five patients with PAD were consecutively enrolled in this study. PA was assessed using the post-EVT step count and the pre-EVT International Physical Activity Questionnaire. Sarcopenia was diagnosed based on the Asia Working Group for Sarcopenia and defined as low muscle mass and strength, and/or slow walking speed. The patients were categorized into three groups: 1) patients with sarcopenia (Sarcopenia Group); 2) patients with only low muscle mass or strength, and/or slow walking speed (Suspected-Sarcopenia Group); and 3) patients who did not fulfill all the sarcopenia criteria (No-Sarcopenia Group).

RESULTS

Proportions of patients in the Sarcopenia, Suspected-Sarcopenia, and No-Sarcopenia Groups were 31.4, 38.1, and 30.5%, respectively. After controlling for potential confounders, the Sarcopenia Group demonstrated significantly lower step counts than the Suspected-Sarcopenia Group (p = .016) and No-Sarcopenia Group (p = .009).

CONCLUSIONS

Our findings indicate that patients with PAD and sarcopenia require rehabilitation strategies to enhance physical performance.

The effects of sedentary behaviour on patients with peripheral arterial Disease: A systematic review

Sedentary behavior has recently emerged as a risk factor for cardiometabolic diseases. The objective of this review was to assess the relationship between sedentary behavior and peripheral arterial disease (PAD). Using the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, we performed an electronic search across databases including Cochrane Central Register of Controlled Trials, Embase, MEDLINE (Ovid), CINHAL and PubMed to identify studies focusing on sedentary behavior and PAD. A total of 678 records fulfilled eligibility; 166 duplicates were removed, 487 were excluded at the title and abstract level and 15 studies were excluded at the full article level. Thus, our review comprised 10 studies of 20,064 patients with mean age 67.4 years. The average sedentary time was 544.9 min/day. The current review findings indicate that patients with PAD exhibited prolonged periods of sedentary behavior. Furthermore, sedentary behavior among patients with PAD was associated with lower survival rates. The included studies also reported varied outcomes regarding walking distance with some showing an association between reduced sedentary behavior and increased total walking distance. A randomized controlled trial in this review highlighted that reducing sedentary time among patients with PAD improved walking distance. Therefore, the connection between sedentary behavior and PAD seems to be bidirectional. Sedentary time could contribute to PAD development, and PAD-related symptoms may lead to prolonged sedentary behavior. A call for research investigating the link between PAD and sedentary time. Additionally, intervention studies are needed to target the reduction of sedentary time in patients with PAD.

The Effect of Exercise Modalities on Walking Capacity in Patients With Intermittent Claudication: A NETWORK META-ANALYSIS

INTRODUCTION

Despite extensive research on the effect of supervised exercise therapy on walking performance in patients with symptomatic peripheral arterial disease (PAD), it remains unclear which training modality provides the greatest improvement in walking capacity. The objective of this study was to compare the effect of different types of supervised exercise therapy on walking capacity in individuals with symptomatic PAD.

METHODS

A random-effect network meta-analysis was performed. The following databases were searched from January 1966 to April 2021: SPORTDiscus, CINAHL, MEDLINE, AMED, Academic Search Complete and, Scopus. Trials had to include at least one type of supervised exercise therapy for patients with symptomatic PAD, with an intervention lasting ≥2 wk with ≥5 training sessions, and an objective measure of walking capacity.

RESULTS

Eighteen studies were included for a total sample of 1135 participants. Interventions duration ranged from 6-24 wk and included aerobic exercise (treadmill walking, ergometer, and Nordic walking), resistance training (lower and/or upper body), a combination of both, and underwater exercise. Results showed that combined training improved treadmill walking capacity to a comparable extent to aerobic walking (+122.0 [24.2-219.8] m vs +106.8 [34.2-179.4] m), but with a larger effect size (1.20 [0.50-1.90] vs 0.67 [0.22-1.11]). Similar results were observed for the 6-min walk distance, with combined training being the most promising modality (+57.3 [16.2-98.5] m), followed by underwater training (+56.5 [22.4-90.5] m) and aerobic walking (+39.0 [12.8-65.1] m).

CONCLUSION

While not statistically superior to aerobic walking, combined exercise seems to be the most promising training modality. Aerobic walking and underwater training also improved walking capacity for patients with symptomatic PAD.

A comparison of the perceptions of wearing an ankle foot orthosis by individuals with peripheral artery disease according to their baseline-level of physical activity

INTRODUCTION

Peripheral artery disease (PAD) is a prevalent cardiovascular disease that limits an individual's ability to walk. One potential way to improve physical activity for patients with PAD is an ankle foot orthosis (AFO). Previous research has found that various factors may influence an individual's willingness to wear AFOs. However, one factor that has been understudied is an individual's baseline physical activity level prior to wearing AFOs. Therefore, the purpose of this study was to compare the perceptions of wearing AFOs for 3 months among individuals with PAD according to their baseline level of physical activity.

METHODS

Accelerometer-derived physical activity prior to AFO prescription was used to classify participants into either a higher or lower activity group. Semi-structured interviews were conducted at 1.5 and 3-months after wearing the AFOs to assess participants' perceptions of using the orthosis. Data were analyzed by a directed content analysis approach, then the percentage of respondents for each theme were calculated and compared between higher and lower activity groups.

FINDINGS

Several differences were found. Participants in the higher activity group more often reported positive impacts from wearing the AFOs. Additionally, participants who were in the lower activity group more often reported the AFOs caused physical pain while participants in the higher activity group more often reported the device was uncomfortable during daily activities.

CONCLUSION

Baseline physical activity levels may help to better understand barriers to wear and needed support to increase adherence to an AFO wear prescription, especially for patients with PAD with limited activity.

Device-measured physical activity behaviours, and physical function, in people with type 2 diabetes mellitus and peripheral artery disease: A cross-sectional study

AIM

To quantify differences in device-measured physical activity (PA) behaviours, and physical function (PF), in people with type 2 diabetes mellitus (T2DM) with and without peripheral artery disease (PAD).

MATERIALS AND METHODS

Participants from the Chronotype of Patients with T2DM and Effect on Glycaemic Control cross-sectional study wore accelerometers on their non-dominant wrist for up to 8-days to quantify: volume and intensity distribution of PA, time spent inactive, time in light PA, moderate-to-vigorous PA in at least 1-minute bouts (MVPA1min), and the average intensity achieved during the most active continuous 2, 5, 10, 30, and 60-minute periods of the 24-h day. PF was assessed using the short physical performance battery (SPPB), the Duke Activity Status Index (DASI), sit-to-stand repetitions in 60 s (STS-60); hand-grip strength was also assessed. Differences between subjects with and without PAD were estimated using regressions adjusted for possible confounders.

RESULTS

736 participants with T2DM (without diabetic foot ulcers) were included in the analysis, 689 had no PAD. People with T2DM and PAD undertake less PA (MVPA1min: -9.2 min [95 % CI: -15.3 to -3.0; p = 0.004]) (light intensity PA: -18.7 min [-36.4 to -1.0; p = 0.039]), spend more time inactive (49.2 min [12.1 to 86.2; p = 0.009]), and have reduced PF (SPPB score: -1.6 [-2.5 to -0.8; p = 0.001]) (DASI score: -14.8 [-19.8 to -9.8; p = 0.001]) (STS-60 repetitions: -7.1 [-10.5 to -3.8; p = 0.001]) compared to people without; some differences in PA were attenuated by confounders. Reduced intensity of activity for the most active continuous 2-30 min in the 24-h day, and reduced PF, persisted after accounting for confounders. There were no significant differences in hand-grip strength.

CONCLUSIONS

Findings from this cross-sectional study suggest that, the presence of PAD in T2DM may have been associated with lower PA levels and PF.

A biomechanical perspective on walking in patients with peripheral artery disease

The most common symptom of peripheral artery disease (PAD) is intermittent claudication, which consists of debilitating leg pain during walking. In clinical settings, the presence of PAD is often noninvasively evaluated using the ankle-brachial index and imaging of the arterial supply. Furthermore, various questionnaires and functional tests are commonly used to measure the severity and negative effect of PAD on quality of life. However, these evaluations only provide information on vascular insufficiency and severity of the disease, but not regarding the complex mechanisms underlying walking impairments in patients with PAD. Biomechanical analyses using motion capture and ground reaction force measurements can provide insight into the underlying mechanisms to walking impairments in PAD. This review analyzes the application of biomechanics tools to identify gait impairments and their clinical implications on rehabilitation of patients with PAD. A total of 18 published journal articles focused on gait biomechanics in patients with PAD were studied. This narriative review shows that the gait of patients with PAD is impaired from the first steps that a patient takes and deteriorates further after the onset of claudication leg pain. These results point toward impaired muscle function across the ankle, knee, and hip joints during walking. Gait analysis helps understand the mechanisms operating in PAD and could also facilitate earlier diagnosis, better treatment, and slower progression of PAD.

Accelerometer assessed upper limb activity in people with stroke: a validation study considering ambulatory and non-ambulatory activities

PURPOSE

Accelerometry measurements are a promising method to provide quantitative information of upper limb function in daily life post stroke. Our purpose was to investigate i) the validity of accelerometer-based vector magnitude ratios (VMR) to distinguish upper limb function between individuals post-stroke and healthy controls during ambulatory and non-ambulatory activities and, ii) the association between the VMR and clinical assessment of upper limb function for individuals post-stroke.

METHODS

Forty persons with stroke and 32 healthy controls wore wrist and hip accelerometers while performing three upper limb activities in a clinical setting and during three days in daily living. Clinical assessment of upper limb function was assessed with the Chedoke-McMaster Stroke Assessment measure and ABILHand.

RESULTS

In the clinical setting and daily living, the VMR was significantly lower for individuals post-stroke compared to controls during non-ambulatory activities but not during ambulatory activities. There was a moderate to strong association between VMR and clinical assessment of upper limb function during all conditions, except for walking in the clinical setting.

CONCLUSION

The VMR could be used as a sensitive objective marker to measure upper limb function post-stroke during ambulatory and non-ambulatory daily activities.Implications for rehabilitationAccelerometer-based assessment of upper limb function is a sensitive measure of upper limb function post stroke during different activity domains.Accelerometers-based assessment of arm function can detect differences in arm function outside the clinical setting (daily living) over a prolonged period that are not always identified by clinical assessment or perceived ability.

Assessing Wear Time and Perceptions of Wearing an Ankle Foot Orthosis in Patients with Peripheral Artery Disease

BACKGROUND

Peripheral artery disease (PAD) is a cardiovascular disease that effects patients' walking ability. An ankle foot orthosis (AFO) may improve patients' walking distances. Little research has explored if patients wear a prescribed AFO and their perceptions of wearing the device.

OBJECTIVE

To assess wear time of an AFO and explore perceptions of wearing the device in patients with peripheral artery disease.

DESIGN

Convergent mixed methods.

SETTING

The study was administered through a tertiary care medical center and the research subjects used the device in an outpatient setting in and out of their homes during their regular activities.

PARTICIPANTS

Patients were referred to the study by their vascular surgeon. Thirty-six patients, all older adult males, were enrolled in this study. Fourteen patients completed the study and 11 supplied sufficient accelerometer data.

INTERVENTIONS

An AFO was worn for 3 months. An accelerometer was placed on the AFO for 7 days at midpoint (1.5 months) and endpoint of the intervention (3 months) to assess wear time. Semi-structured interviews explored patients' perceptions of wearing the AFO.

MAIN OUTCOME MEASURE

The primary outcome measure was wear time measured objectively via accelerometer and subjectively via interview.

RESULTS

Patients (n = 14) wore the AFO around 8 hours/day. Most patients felt they wore the AFO a majority of the time. Patients reported barriers such as challenges wearing the AFO during daily household activities (using stairs, being on uneven terrain), discomfort, clothing or footwear issues, and driving challenges. Positive impacts of wearing the AFO were also reported, primarily the ability to walk further.

CONCLUSIONS

An AFO may be an acceptable therapeutic intervention to improve perceived walking performance in older adult males with PAD. Addressing patients' perceptions of the AFO and barriers to wear are essential to increasing the positive impact the device has on patients' ambulatory activity. This article is protected by copyright. All rights reserved.

Muscle forces and power are significantly reduced during walking in patients with peripheral artery disease

Patients with peripheral artery disease (PAD) have significantly reduced lower extremity muscle strength compared with healthy individuals as measured during isolated, single plane joint motion by isometric and isokinetic strength dynamometers. Alterations to the force contribution of muscles during walking caused by PAD are not well understood. Therefore, this study used simulations with PAD biomechanics data to understand lower extremity muscle functions in patients with PAD during walking and to compare that with healthy older individuals. A total of 12 patients with PAD and 10 age-matched healthy older controls walked across a 10-meter pathway with reflective markers on their lower limbs. Marker coordinates and ground reaction forces were recorded and exported to OpenSim software to perform gait simulations. Walking velocity, joint angles, muscle force, muscle power, and metabolic rate were calculated and compared between patients with PAD and healthy older controls. Our results suggest that patients with PAD walked slower with less hip extension during propulsion. Significant force and power reductions were observed in knee extensors during weight acceptance and in plantar flexors and hip flexors during propulsion in patients with PAD. The estimated metabolic rate of walking during stance was not different between patients with PAD and controls. This study is the first to analyze lower limb muscular responses during walking in patients with PAD using the OpenSim simulation software. The simulation results of this study identified important information about alterations to muscle force and power during walking in those with PAD.

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.

A Scoping Review of Physical Activity in People With Lower-Limb Loss: 10,000 Steps Per Day?

OBJECTIVE

After amputation, people with lower-limb loss (PLL) face challenges to regain their previous physical activity level. Assessing the scope of evidence regarding physical activity in PLL can identify sources of evidence and gaps within the literature that can influence amputation-related research, outcome assessment choices, and wellness activities. The purpose of this scoping review was to map the evidence regarding steps per day as a physical activity measure for PLL. Specific aims were to (1) identify research designs, (2) catalog population subgroups, (3) document steps per day measurement methods, and (4) provide descriptive data for steps per day in PLL.

METHODS

The MEDLINE, CINAHL, Embase, Web of Science, and AMED databases; and the Journal of Prosthetics and Orthotics archive were searched without language or time limits. Exclusion criteria included no PLL subjects, not peer-reviewed, and no direct step count measure. Inclusion criteria allowed any sample size, nonprosthetic use, and self-reported step count. As a scoping review, only descriptive statistics were compiled, and no methodologic quality assessment was performed.

RESULTS

Twenty-one articles using crossover (8), cohort (4), cross-section (8), and case-study (1) designs were included that reported accelerometer (19) or pedometer (2) data. Studies often mixed amputation etiologies (15/21) and most (13/21) excluded transfemoral amputations. Studies primarily examined people with transtibial amputations (81.2%) and people at independent community walking levels (Medicare functional classifications: K3 = 49.2%, K4 = 36.3%). All 21 studies had fewer than 100 participants, and overall included 515 subjects (343, 66.6% male), mean (SD) age 53.2 (22.1) years. Mean (SD) number of pooled steps per day for PLL was 5087 (2998): 5929 (3047) for transtibial amputations and 3553 (2030) for transfemoral amputations.

CONCLUSIONS

Most PLL have low activity levels compared with the 10,000 steps per day generally recommended or 6000 common in people with diabetes. Research with larger samples, defined subgroups, and data along the recovery continuum would enhance knowledge of physical activity level in PLL.

IMPACT

This scoping review has identified gaps in the research related to steps per day as a measure of physical activity in people with lower-limb loss to guide future research.

LAY SUMMARY

People with lower-limb loss take fewer steps per day than suggested for general health. Increasing steps per day may be a useful goal for this population, and this study is a first step in improving knowledge of physical activity levels in people with lower-limb loss.

Gait variability is affected more by peripheral artery disease than by vascular occlusion

Background

Patients with peripheral artery disease with intermittent claudication (PAD-IC) have altered gait variability from the first step they take, well before the onset of claudication pain. The mechanisms underlying these gait alterations are poorly understood.

Aims

To determine the effect of reduced blood flow on gait variability by comparing healthy older controls and patients with PAD-IC. We also determined the diagnostic value of gait variability parameters to identify the presence of PAD.

Methods

A cross-sectional cohort design was used. Thirty healthy older controls and thirty patients with PAD-IC walked on a treadmill at their self-selected speed in pain free walking (normal walking for healthy older controls; prior to claudication onset for PAD) and reduced blood flow (post vascular occlusion with thigh tourniquet for healthy older controls; pain for PAD) conditions. Gait variability was assessed using the largest Lyapunov exponent, approximate entropy, standard deviation, and coefficient of variation of ankle, knee, and hip joints range of motion. Receiver operating characteristics curve analyses of the pain free walking condition were performed to determine the optimal cut-off values for separating individuals with PAD-IC from those without PAD-IC.

Results and discussion

Patients with PAD-IC have increased amount of variability for knee and hip ranges of motion compared with the healthy older control group. Regarding the main effect of condition, reduced blood flow demonstrated increased amount of variability compared with pain free walking. Significant interactions between group and condition at the ankle show increased values for temporal structure of variability, but a similar amount of variability in the reduced blood flow condition. This demonstrates subtle interactions in the movement patterns remain distinct between PAD-IC versus healthy older controls during the reduced blood flow condition. A combination of gait variability parameters correctly identifies PAD-IC disease 70% of the time or more.

Conclusions

Gait variability is affected both by PAD and by the mechanical induction of reduced blood flow. Gait variability parameters have potential diagnostic ability, as some measures had 90.0% probability of correctly identifying patients with PAD-IC.

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.

Synthesis and characterization of a hyaluronic acid-based hydrogel with antioxidative and thermosensitive properties

Peripheral arterial disease (PAD) is initiated by progressive atherosclerotic blockages of the arteries supplying the lower extremities. The most common presentation of PAD is claudication (leg pain and severe walking limitation), with many patients progressing to limb threatening ischemia and amputation. Biomaterial approaches are just beginning to be explored in the therapy of PAD with different materials now being evaluated for the delivery of cells or growth factors in animal models of PAD. A biomaterial matrix optimized for minimally invasive injection in the ischemic leg muscles of patients with PAD is urgently needed. There are several important requirements for optimal delivery, retention, and performance of a biomaterial matrix in the mechanically, histologically, and biochemically dynamic intramuscular environment of the PAD leg. Ideally, the material should have mechanical properties matching those of the recipient muscle, undergo minimal swelling, and should introduce properties that can ameliorate the mechanisms operating in PAD like oxidative stress and damage. Here we have developed an injectable, antioxidative, and thermosensitive hydrogel system based on hyaluronic acid (HA). We first synthesized a unique crosslinker of disulfide-modified poloxamer F127 diacrylate. This crosslinker led to the creation of a thermosensitive HA hydrogel with minimal swelling and muscle-matching mechanical properties. We introduced unique disulfide groups into hydrogels which functioned as an effective reactive oxygen species scavenger, exhibited hydrogen peroxide (H2O2)-responsive degradation, and protected cells against H2O2-induced damage. Our antioxidative thermosensitive HA hydrogel system holds great potential for the treatment of the ischemic legs of patients with PAD.

Influence of Changes in Sedentary Time on Outcomes of Supervised Exercise Therapy in Individuals with Comorbid Peripheral Artery Disease and Type 2 Diabetes

BACKGROUND

Although supervised exercise therapy (SET) is effective in improving walking distance among adults with symptomatic peripheral artery disease (PAD), some research suggests that individuals with comorbid PAD and type 2 diabetes mellitus (T2DM) may experience a blunted response to SET. It is unknown whether free-living sedentary time changes during SET, and if increases in sedentary time could, in part, explain poor response to SET. The purposes of this pilot study were to (1) determine if older adults with PAD (with and without T2DM) engaging in SET change their sedentary behavior and (2) examine the relationship between changes in sedentary behavior and SET outcomes. We hypothesized that decreased sedentary time during SET would be associated with greater improvements in six-minute walk test (6MWT) total distance and other key SET outcomes.

METHODS

Participants (n = 44) initiating a 12-week SET program completed the 6MWT, Short Physical Performance Battery, Walking Impairment Questionnaire, and accelerometer-assessed sedentary behavior at SET initiation, 6 weeks, and 12 weeks.

RESULTS

Participants' mean age was 72.3 (7.1) years, mean ankle-brachial index was 0.71 (0.25), and 47.7% were female. On average, sedentary time did not change after SET, although there was substantial variability (-40% to +38% change in minutes of sedentary time/day). Participants with T2DM experienced greater improvements in claudication onset distance than participants without T2DM (mean = 35 m, P = 0.044, 95% confidence interval = 1.6 to 115.4 m). Neither changes in sedentary time from baseline to 6 weeks (P = 0.419) nor T2DM (P = 0.154) predicted changes in 6MWT total distance from baseline to 12 weeks.

CONCLUSIONS

As SET availability increases, further examination of factors that may influence SET outcomes will help maximize benefits of this proven therapy.

A low-cost, wireless near-infrared spectroscopy device detects the presence of lower extremity atherosclerosis as measured by computed tomographic angiography and characterizes walking impairment in peripheral artery disease

BACKGROUND

Patients with peripheral artery disease (PAD) who experience intermittent claudication report a range of symptoms. Patients with symptoms other than classically described intermittent claudication may be at the highest risk for functional decline and mobility loss. Therefore, technologies allowing for characterization of PAD severity are desirable. Near-infrared spectroscopy (NIRS) allows for measurements of muscle heme oxygen saturation (StO₂) during exercise. We hypothesized lower extremities affected by PAD would exhibit distinct NIRS profiles as measured by a low-cost, wireless NIRS device and that NIRS during exercise predicts walking limitation.

METHODS

We recruited 40 patients with PAD and 10 control participants. All patients with PAD completed a computed tomographic angiography, 6-minute walk test, and a standardized treadmill test. Controls completed a 540-second treadmill test for comparison. StO₂ measurements were continuously taken from the gastrocnemius during exercise. Variables were analyzed by Fischer's exact, χ², Wilcoxon rank-sum, and Kruskal-Wallis tests as appropriate. Correlations were assessed by partial Spearman correlation coefficients adjusted for occlusive disease pattern.

RESULTS

Patients with PAD experienced claudication onset at a median of 108 seconds with a median peak walking time of 288 seconds. The baseline StO₂ was similar between PAD and control. The StO₂ of PAD and control participants dropped below baseline at a median of 1 and 104 seconds of exercise, respectively (P < .0001). Patients with PAD reached minimum StO₂ earlier than control participants (119 seconds vs 522 seconds, respectively; P < .001) and experienced a greater change in StO₂ at 1 minute of exercise (-73.2% vs 8.3%; P < .0001) and a greater decrease at minimum exercise StO₂ (-83.4% vs -16.1%; P < .0001). For patients with PAD, peak walking time, and 6-minute walking distance correlated with percent change in StO₂ at 1 minute of exercise (r = -0.76 and -0.67, respectively; P < .001) and time to minimum StO₂ (r = 0.79 and 0.70, respectively; P < .0001).

CONCLUSIONS

In this initial evaluation of a novel, low-cost NIRS device, lower extremities affected by PAD exhibited characteristic changes in calf muscle StO₂, which differentiated them from healthy controls and were strongly correlated with walking impairment. These findings confirm and expand on previous work demonstrating the potential clinical value of NIRS devices and the need for further research investigating the ability of low-cost NIRS technology to evaluate, diagnose, and monitor treatment response in PAD.