Associations between lower extremity ischemia, upper and lower extremity strength, and functional impairment with peripheral arterial disease

Association between grip strength, walking pace and incident peripheral artery disease: A prospective study of 430,886 UK biobank participants

Background and aims

Patients with peripheral artery disease (PAD) presented overall muscle weakness and reduced physical performance. Previous study focused on the impact of muscle weakness on outcomes of established PAD, however the relationship between compromised muscle function and incident PAD remained unclear.

Methods

A prospective study involving 430,886 participants aged 40-69 y from UK biobank was conducted. The main outcome was incident PAD. Grip strength and walking pace were used as indicators for muscle function. Grip strength was measured using a Jamar J00105 hydraulic hand dynamometer, while walking pace was self-reported by the participants. Cox proportional hazard models were employed to investigate the relationship between grip strength, walking pace, and incident PAD.

Results

A total of 430,886 individuals were included in the final analysis. The mean age of the participants were 56.44 years, and 55.3 % were female. Over a median follow-up period of 13.81 years, 5,661 participants developed PAD. Higher grip strength, whether absolute or relative, exhibited a dose-dependent inverse association with incident PAD. Each 1 kg increment in absolute grip strength and each 0.01 kg/kg increase in relative grip strength were associated with reduced PAD risk by 2 % (HR: 0.98; 95 % CI [0.97-0.98]) and 83 % (HR: 0.17; 95 % CI [0.13-0.23]), respectively. Slow walking pace significantly correlated with increased PAD risk, while brisk walking pace was associated with decreased PAD risk.

Conclusion

Absolute grip strength, relative grip strength and walking pace were inversely associated with the risk of incident PAD.

Association of endothelial dysfunction and peripheral arterial disease with sarcopenia in chronic kidney disease

BACKGROUND

Endothelial dysfunction and peripheral arterial disease (PAD), which disturb skeletal muscle microperfusion, are highly prevalent in patients with chronic kidney disease (CKD). We evaluated the association of endothelial dysfunction and PAD with sarcopenia in patients with non-dialysis CKD.

METHODS

This cross-sectional study included 420 patients with stages 3-5 non-dialysis CKD aged 69.0 ± 11.8 years. Skeletal muscle index (skeletal muscle mass/height2), handgrip strength, 6-m gait speed and strength of hip flexion and knee extension were measured. Sarcopenia was defined according to the Asian Working Group for Sarcopenia 2019. Endothelial dysfunction and PAD were assessed using the vascular reactivity index (VRI) and ankle-brachial index (ABI), respectively. A VRI < 1.0 was classified as poor endothelial function, and an ABI < 0.9 was defined as PAD. Additionally, endothelial and inflammatory biomarkers, including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), asymmetric dimethylarginine, endothelin-1 (ET-1) and interleukin-6, were measured in a subgroup of 262 patients.

RESULTS

Among the participants, 103 (24.5%) were classified as having sarcopenia. Compared with patients without sarcopenia, those with sarcopenia had significantly lower ABI (1.04 ± 0.16 vs. 1.08 ± 0.15, P = 0.028 for the right ABI; 1.01 ± 0.16 vs. 1.06 ± 0.16, P = 0.002 for the left ABI) and VRI (0.83 ± 0.57 vs. 1.08 ± 0.56, P < 0.001) and had higher serum levels of ICAM-1 (P < 0.001), VCAM-1 (P = 0.003) and ET-1 (P = 0.037). Multivariate logistic regression revealed that, beyond age and body mass index, the average ABI (odds ratio [OR]: 0.81/0.1 increase; 95% confidence interval [CI]: 0.67-0.98; P = 0.032) and VRI (OR: 0.93/0.1 increase; 95% CI: 0.88-0.98; P = 0.010) were independently associated with sarcopenia. Among the endothelial biomarkers measured, ICAM-1 (OR: 2.47/1-SD increase; 95% CI: 1.62-3.75) and VCAM-1 (OR: 1.91/1-SD increase; 95% CI: 1.27-2.87) were independent predictors of sarcopenia. Group stratification based on the cut-offs of VRI and ABI showed that those with both poor VRI and ABI had the greatest risk for sarcopenia (OR: 4.22; 95% CI: 1.69-10.49), compared with those with normal VRI and ABI.

CONCLUSIONS

Endothelial dysfunction and PAD are independently associated with sarcopenia in patients with stages 3-5 CKD, suggesting the dominant role of vascular dysfunction in sarcopenia.

Exercise therapy for chronic symptomatic peripheral artery disease

All guidelines worldwide strongly recommend exercise as a pillar of the management of patients affected by lower extremity peripheral artery disease (PAD). Exercise therapy in this setting presents different modalities, and a structured programme provides optimal results. This clinical consensus paper is intended for clinicians to promote and assist for the set-up of comprehensive exercise programmes to best advice in patients with symptomatic chronic PAD. Different exercise training protocols specific for patients with PAD are presented. Data on patient assessment and outcome measures are narratively described based on the current best evidence. The document ends by highlighting disparities in access to supervised exercise programmes across Europe and the series of gaps for evidence requiring further research.

Exercise therapy for chronic symptomatic peripheral artery disease

All guidelines worldwide strongly recommend exercise as a pillar in the management of patients affected by lower extremity peripheral artery disease (PAD). Exercise therapy in this setting presents different modalities, and a structured programme provides optimal results. This clinical consensus paper is intended to promote and assist the set up of comprehensive exercise programmes and best advice for patients with symptomatic chronic PAD. Different exercise training protocols specific for patients with PAD are presented. Data on patient assessment and outcome measures are described based on the current best evidence. The document ends by highlighting supervised exercise programme access disparities across Europe and the evidence gaps requiring further research.

Winners do what they fear: exercise and peripheral arterial disease-an umbrella review

AIMS

This systematic review aims to evaluate and summarize findings from published meta-analyses on the effects of regular exercise in patients with peripheral arterial disease (PAD). The review will assess the impact of exercise on functional parameters, health-related quality of life, haemodynamic parameters, physical activity levels, adverse events, and mortality.

METHODS AND RESULTS

A systematic search was performed in PubMed, Web of Science, Scopus, and Cochrane Library databases (up to May 2023) to identify meta-analyses including randomized controlled trials that examined the effects of regular exercise in patients with PAD. Sixteen studies, with a total of 198 meta-analyses, were identified. Results revealed with strong evidence that patients with PAD who exercised improved functional and health-related quality of life parameters. Specifically, supervised aerobic exercise (i.e. walking to moderate-maximum claudication pain) improves maximum walking distance [mean difference (MD): 177.94 m, 95% confidence interval (CI) 142.29-213.60; P < 0.00001; I2: 65%], pain-free walking distance (fixed MD: 68.78 m, 95% CI 54.35-83.21; P < 0.00001; I2: 67%), self-reported walking ability [i.e. distance score (MD: 9.22 points, 95% CI 5.74-12.70; P < 0.00001; I2: 0%), speed score (MD: 8.71 points, 95% CI 5.64-11.77; P < 0.00001, I2: 0%), stair-climbing score (MD: 8.02 points, 95% CI 4.84-11.21; P < 0.00001, I2: 0%), and combined score (MD: 8.76 points, 95% CI 2.78-14.74; P < 0.0001, I2: 0%)], aerobic capacity (fixed MD: 0.62 mL/kg/min, 95% CI 0.47-0.77, P < 0.00001, I2: 64%), and pain score (MD: 7.65, 95% CI 3.15-12.15; P = 0.0009; I2: 0%), while resistance exercise improves lower limb strength (standardized mean difference: 0.71, 95% CI 0.29-1.13, P = 0.0009; I2: 0%]. Regarding other outcomes, such as haemodynamic parameters, no significant evidence was found, while physical activity levels, adverse events, and mortality require further investigation.

CONCLUSION

Synthesis of the currently available meta-analyses suggests that regular exercise may be beneficial for a broad range of functional tasks improving health-related quality of life in patients with PAD. Supervised aerobic exercise is the best type of exercise to improve walking-related outcomes and pain, while resistance exercise is more effective to improve lower limb strength.

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.

Exercise Therapy for Chronic Symptomatic Peripheral Artery Disease: A Clinical Consensus Document of the European Society of Cardiology Working Group on Aorta and Peripheral Vascular Diseases in Collaboration With the European Society of Vascular Medicine and the European Society for Vascular Surgery

All guidelines worldwide strongly recommend exercise as a pillar in the management of patients affected by lower extremity peripheral artery disease (PAD). Exercise therapy in this setting presents different modalities, and a structured programme provides optimal results. This clinical consensus paper is intended to promote and assist the set up of comprehensive exercise programmes and best advice for patients with symptomatic chronic PAD. Different exercise training protocols specific for patients with PAD are presented. Data on patient assessment and outcome measures are described based on the current best evidence. The document ends by highlighting supervised exercise programme access disparities across Europe and the evidence gaps requiring further research.

Effect of Early Rehabilitation on Gait, Wound and Home Discharge in Lower Extremity Chronic Wound Patients: A Japanese Multicenter Retrospective Study

This study investigated the effect of early rehabilitation on gait restoration, wound healing, and home discharge in patients with lower extremity (LE) chronic wounds. This multicenter, retrospective cohort study included 233 Japanese inpatients who received treatment for LE chronic wounds from April 2012 to March 2015. A multivariate analysis was conducted using outcomes of gait restoration, wound healing, and home discharge as dependent variables. Other survey items were used as independent variables. Early rehabilitation was extracted as an independent factor with gait restoration (hazard ratio [HR] 1.82, P < .01) and home discharge (HR 1.77, P < .001) as dependent factors by the stepwise method in Cox proportional-hazards regression analysis, but it was not extracted as an independent factor with wound healing as the dependent factor by the stepwise method as well as the forced entry method (P = .44). A significant relationship between the presence of gait restoration and home discharge was observed in the chi-square test (P<.001), and the duration from admission to gait restoration was significantly correlated to the duration from admission to home discharge (Pearson's product-moment correlation coefficient; r=.89, P<.0001). Early rehabilitation was a positive factor for gait restoration and home discharge in chronic LE wound patients.

Relationship Between Physical Performance and Peripheral Arterial Diseases in Different Age Groups of Chinese Community-Dwelling Older Adults

Aims: This study aimed to examine the relationship between physical performance and peripheral artery disease (PAD) in different age groups of Chinese older adults.

Methods: We enrolled 1357 relatively healthy ≥ 65 years old participants of Chinese ethnicity. We classified the participants into two age categories, the pre-old group (65–74 years,n =968) and the old group (≥ 75 years,n =389). We assessed the cross-sectional association of the ankle–brachial index (ABI), which is used for the classification of patients with PAD (ABI ≤ 0.9). Physical performance mainly focused on muscle strength, mobility, and balance, which were measured via hand grip, 4 m walking speed, and the Timed Up and Go Test.

Results: A total of 125 (9.2%) patients met the diagnostic criteria and were defined as having PAD. After multivariate adjustment, we found that grip strength and 4 m walking speed were correlated negatively with PAD (odds ratio (OR)=0.953, 95% confidence interval (CI)=0.919–0.989; OR=0.296, 95% CI=0.093–0.945) in pre-old participants, whereas balance (OR=1.058, 95% CI=1.007–1.112) was correlated positively with PAD only in older participants.

Conclusion: Our study further confirmed the association between physical performance and PAD in community-dwelling older Chinese adults. Muscle strength and mobility correlated negatively with PAD, and balance was positively associated with PAD in older participants. These findings might help with better early screening and management of PAD.

Sit to Stand Muscle Power Is Related to Functional Performance at Baseline and After Supervised Exercise Training in Patients with Lower Extremity Peripheral Artery Disease

OBJECTIVE

Patients with peripheral artery disease (PAD) have decreased muscle power, contributing to functional limitations. The sit to stand (STS) is a validated test to assess muscle power in older individuals; however, it has never been investigated in patients with PAD. The relationship between STS muscle power, and common disease related outcomes was evaluated at baseline and following supervised exercise training (SET) in patients with PAD.

METHODS

This observational study investigated patients with Fontaine stage II. Before and after SET, maximum treadmill walking distance (MWD), functional performance tests (six minute walk, STS, stair climbing, habitual gait speed), and quality of life (Short Form 36 questionnaire) were assessed. Relative (W/kg) STS muscle power was calculated using a validated equation. Multiple regressions models were used.

RESULTS

Ninety-five patients with PAD were included (63.1 ± 12.1 years, 67% male). Relative STS muscle power before: 2.7 W/kg, 95% confidence interval [CI] 2.5 - 2.9; after: 3.3, 95% CI 3.1 - 3.6, MWD before: 367.0 m, 95% CI 302.4 - 431.5; after: 598.4, 95% CI 515.6 - 681.3, six minute walking distance before: 418.3 metres; 95% CI 399.4 - 437.2; after: 468.8; 95% CI 452.7-484.9, stair climbing performance before: 6.8 seconds 95% CI 6.2 - 7.4); after: 5.3; 95% CI 4.9 - 5.7, habitual gait speed before: 1.10 m/s, 95% CI 1.05 - 1.14; after: 1.18, 95% CI 1.14 - 1.22 increased significantly following SET (p < .001). Similarly, physical before: 31.4, 95% CI 29.4 - 33.3; after: 35.8, 95% CI 33.9 - 37.7 and mental before: 39.5, 95% CI 37.0 - 42.0; after: 43.1, 95% CI 40.9 - 45.4 component summaries of the SF-36 also increased significantly (p < .001). Greater relative STS muscle power at baseline was significantly related to greater baseline treadmill (β < .380; p < .002) and functional (β < .597; p < .001) performance, and quality of life (β < .291; p < .050). Larger increases in relative STS muscle power following SET were associated with greater improvements in functional performance (β < .419; p < .009).

CONCLUSION

The STS test is a valid clinical tool to monitor overall functional status in patients with symptomatic PAD.

Combined Effect of Dynapenia and Abdominal Obesity on the Prevalence of Peripheral Artery Disease in Older Adults Over 75 Years Old in China

The objective is to examine the separate and joint effects of dynapenia and abdominal obesity on the prevalence of peripheral artery disease (PAD) in older adults of different ages (60-74 and over 75 years old). This study comprised 1293 community-dwelling Chinese participants recruited from Shanghai, China, who were aged at least 60 years (753 women; mean age: 72.0 ± 5.9 years). Dynapenia was defined as low-grip strength (<28.0 kg for males and <18.0 kg for females) but normal skeletal muscle index (≥7.0 kg/m² for males and ≥5.7 kg/m² for females). Abdominal obesity was determined according to waist circumference (≥90 cm for males and ≥85 cm for females), and PAD was diagnosed by an ankle-brachial index  ≤ 0.9. Binary logistic regression models were performed to determine associations between dynapenia, abdominal obesity, and the combination of dynapenia and abdominal obesity and PAD. According to dynapenia and abdominal obesity status stratified by age (60-74 or over 75), the patients were divided into 4 groups: normal, dynapenia alone, abdominal obesity alone, and co-occurring groups. A logistic regression showed that the co-occurring groups (odds ratio = 4.63, 95% confidence interval = 1.41-15.21) had a higher prevalence of PAD than the normal group after adjusting for the covariates in older adults over 75 years of age. The combination of dynapenia and abdominal obesity increase the prevalence of PAD in older adults over 75 years. The present findings have important implications for the early identification of older adults with PAD and appropriate interventions should be implemented.

Physical function and physical activity in hemodialysis patients with peripheral artery disease

INTRODUCTION

Peripheral artery disease (PAD) is commonly observed in patients undergoing hemodialysis. PAD impairs the vasculature and leads to pathophysiologic changes in the skeletal muscles, causing physical function impairment and physical inactivity in general. However, it is unclear whether PAD adversely affects physical function and physical activity in patients on hemodialysis.

METHODS

We performed a cross-sectional study with a retrospective review of the data to determine whether PAD is associated with impaired physical function and physical activity in patients undergoing hemodialysis. The study population comprised 310 patients and 88 healthy subjects. PAD was diagnosed based on an ankle-brachial index of <1.00 in patients on hemodialysis. Measurements of physical function included maximum walking speed, muscle strength in the lower extremities, and balance while standing.

FINDINGS

Of the 310 patients, 84 (27.1%) had PAD. When patients undergoing hemodialysis were divided into those without PAD and those with PAD, both groups had poorer physical function and physical activity than the healthy control subjects. After adjustments for potential confounders, it was found that patients on hemodialysis with PAD had slower walking speed, poorer standing balance, and less physical activity than those without PAD. However, there was no significant difference in lower extremity muscle strength between the two groups.

DISCUSSION

PAD diagnosed based on an ankle-brachial index of <1.00 was independently associated with impaired physical function and reduced physical activity in patients undergoing hemodialysis.

Lower-extremity muscle wasting in patients with peripheral arterial disease: quantitative measurement and evaluation with CT

OBJECTIVES

Lower-extremity peripheral arterial disease (PAD) results in limb ischemia and is strongly associated with sarcopenia. This study aimed to retrospectively evaluate the association between the quantity of muscle mass in the lower extremities and the severity of vascular stenosis in PAD patients.

METHODS

Between January 2018 and August 2021, 128 patients with PAD and 53 individuals without PAD, diagnosed by computed tomography, were enrolled. The severity of stenosis of lower-extremity arteries was measured using a grading system. The muscle and fat mass areas were calculated in the abdomen at the L3 or L4 level, mid-thigh, and lower leg. Multivariable logistic regression was conducted to clarify the risk associated with low muscle mass. The difference in muscle mass between PAD and non-PAD patients was evaluated by using propensity score matching.

RESULTS

A strong positive correlation between the abdomen muscle area and leg muscle area was observed. The muscle area and muscle index of the leg were lower in PAD patients. These changes occurred earlier than in the abdomen muscle area. The group with more severe artery stenosis had more muscle wasting in the lower extremities. Greater age, female, lower BMI, and PAD were associated with low muscle mass. After propensity score matching, the leg muscle area was still lower in PAD patients.

CONCLUSIONS

There is a direct association between PAD and regional muscle wasting. This occurs earlier regionally in the lower extremities than in central muscles. Early diagnosis of PAD might prevent progressive muscle loss, improving disease outcome and quality of life.

KEY POINTS

• Peripheral arterial disease is strongly associated with sarcopenia. • Muscle wasting in the lower extremities is earlier and more prominent than that in the abdomen. • More severe arterial stenoses are associated with higher muscle wasting in the lower extremities.

Joint Angle Variability Is Altered in Patients with Peripheral Artery Disease after Six Months of Exercise Intervention

Supervised exercise therapy (SET) is a conservative non-operative treatment strategy for improving walking performance in patients with peripheral artery disease (PAD). Gait variability is altered in patients with PAD, but the effect of SET on gait variability is unknown. Forty-three claudicating patients with PAD underwent gait analysis before and immediately after a 6-month SET program. Nonlinear gait variability was assessed using sample entropy, and the largest Lyapunov exponent of the ankle, knee, and hip joint angle time series. Linear mean and variability of the range of motion time series for these three joint angles were also calculated. Two-factor repeated measure analysis of variance determined the effect of the intervention and joint location on linear and nonlinear dependent variables. After SET, walking regularity decreased, while the stability remained unaffected. Ankle nonlinear variability had increased values compared with the knee and hip joints. Linear measures did not change following SET, except for knee angle, in which the magnitude of variations increased after the intervention. A six-month SET program produced changes in gait variability toward the direction of healthy controls, which indicates that in general, SET improved walking performance in individuals with PAD.

Peripheral artery disease and physical function in women with and without HIV

OBJECTIVES

Peripheral artery disease (PAD) is associated with decreased physical function and increased mortality in the general population. We previously found that PAD is common in middle-aged women with and without HIV infection, but its association with functional decline is unclear. We examine the contribution of PAD to functional decline in the Women's Interagency HIV Study, controlling for traditional cardiovascular risk factors and HIV-related factors.

METHODS

Analysis included 1839 participants (72% with HIV) with measured ankle-brachial index (ABI) and 4 m gait speed. ABI values categorized PAD severity. Linear models with repeated measures estimated the association of PAD severity with log-transformed gait speed after controlling for demographic, behavioral, and metabolic risk factors, and HIV/hepatitis C virus status.

RESULTS

Median age was 50 years and more than 70% were Black. Compared with normal ABI, there was a dose-response relationship between increasing PAD severity and slower gait speed in univariable analyses: 6% slower gait speed for low-normal ABI [95% confidence interval (CI): 4-9%], 10% for borderline PAD (95% CI: 6-13%), 14% for mild PAD (95% CI: 9-18%), and 16% for moderate-severe PAD (95% CI: 5-25%). PAD severity remained associated with slower gait speed in multivariable analyses. HIV/hepatitis C virus co-infection was independently associated with 9% (95% CI: 4-14%) slower gait speed compared with those with neither infection. Among women with HIV, neither CD4+ cell count nor HIV-RNA level was associated with gait speed.

CONCLUSION

In middle-aged women with and without HIV infection, greater PAD severity is associated with progressively slower gait speed. Early detection of subclinical PAD may decrease the risk of lower extremity functional impairment and its long-term health consequences.

Ankle-Brachial Index Is a Good Determinant of Lower Limb Muscular Strength but Not of the Gait Pattern in PAD Patients

The aim of this study was to evaluate the relationship of the ankle-brachial index (ABI) level with kinetic and kinematic parameters of the gait pattern and force-velocity parameters generated by lower limb muscles. Methods: The study group consisted of 65 patients with peripheral arterial disease (PAD). The ABI value, kinetic and kinematic parameters of gait and force-velocity parameters of knee and ankle extensors and flexors were determined in all subjects. The values obtained for right and left limbs as well as the limbs with higher and lower ABI were compared. Results: Regardless of the method of analysis, the values of the gait’s kinematic and kinetic parameters of both lower limbs did not differ significantly. However, significant differences were noted in the values of peak torque, work and power of the extensor muscles of the knee and the flexor muscles of the ankle with the higher and lower ABI. Conclusion: This study demonstrated that a higher degree of ischemia worsened the level of strength, endurance, and performance of ankle flexors and extensors of the knee joint. ABI is not related to the gait pattern. The above-mentioned relationship should be taken into account in the rehabilitation process and methodological assessment.

Intra-rater reliability, inter-rater reliability and minimal detectable change of the posterior shoulder endurance test in elite athletes

OBJECTIVE

Investigate intra-rater and inter-rater reliability of the posterior shoulder endurance test (PSET) and calculate minimal detectable change (MDC) to establish measurement properties and inform use of the PSET in practice.

STUDY DESIGN

Test-retest reliability.

SETTING

British Canoe Slalom National Training Centre.

PARTICIPANTS

Twelve participants (7 male, 5 female; 22.5 ± 4.48 years; 73.4 ± 6.36 kg) were investigated by two physiotherapists with >10 years' experience.

MAIN OUTCOME MEASURE

Intraclass correlation coefficients (ICC) were calculated for intra-rater reliability (ICC 3,1) and inter-rater reliability (ICC 2,1) and used to calculate MDC.

RESULTS

Intra-rater reliability scores were 0.84 and 0.85 for rater A and B, respectively, with 95% confidence interval (CI) crossing moderate to excellent reliability for both raters (0.5-0.75 and > 0.9). Inter-rater reliability scores were 0.74 and 0.63 at baseline and follow-up, respectively, with 95% CI crossing poor to good reliability in both time points (<0.5 and >0.75). MDC95% for intra-rater scores was 6 repetitions, MDC95% for inter-rater scores was 8 repetitions at baseline and 9 repetitions at follow-up.

CONCLUSION

The PSET has acceptable intra-rater reliability but further work is needed to narrow the CI to an appropriate level for inter-rater reliability. The MDC calculated helps clinicians interpret changes in tests scores.

Skeletal Muscle Pathology in Peripheral Artery Disease: A Brief Review

This brief review summarizes current evidence regarding lower extremity peripheral artery disease (PAD) and lower extremity skeletal muscle pathology. Lower extremity ischemia is associated with reduced calf skeletal muscle area and increased calf muscle fat infiltration and fibrosis on computed tomography or magnetic resonance imaging. Even within the same individual, the leg with more severe ischemia has more adverse calf muscle characteristics than the leg with less severe ischemia. More adverse computed tomography-measured calf muscle characteristics, such as reduced calf muscle density, are associated with higher rates of mobility loss in people with PAD. Calf muscle in people with PAD may also have reduced mitochondrial activity compared with those without PAD, although evidence is inconsistent. Muscle biopsy document increased oxidative stress in PAD. Reduced calf muscle perfusion, impaired mitochondrial activity, and smaller myofibers are associated with greater walking impairment in PAD. Preliminary evidence suggests that calf muscle pathology in PAD may be reversible. In a small uncontrolled trial, revascularization improved both the ankle-brachial index and mitochondrial activity, measured by calf muscle phosphocreatine recovery time. A pilot clinical trial showed that cocoa flavanols increased measures of myofiber health, mitochondrial activity, and capillary density while simultaneously improving 6-minute walk distance in PAD. Calf muscle pathological changes are associated with impaired walking performance in people with PAD, and interventions that both increase calf perfusion and improve calf muscle health are promising therapies to improve walking performance in PAD.

Sarcopenia and peripheral arterial disease: a systematic review

BACKGROUND

Patients with lower extremity peripheral arterial disease (PAD) and sarcopenia are a population at risk requiring specific and targeted care. The aim of this review is to gather all relevant studies associating sarcopenia and PAD and to identify the underlying pathophysiological mechanisms as well as potential therapeutic strategies to improve skeletal muscle function.

METHODS

A systematic review was carried out following the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA).

RESULTS

Data extraction allowed the evaluation of 140 publications; 87 met the inclusion criteria; of which 79 were included in the final review, reporting sufficient data for epidemiological and diagnostic criteria, mechanical analysis, and therapeutic approaches. Epidemiological analysis and diagnostic criteria were based on 18 studies following 2362 PAD patients [31.39% (SD 7.61) women], aged 72.42 (SD 2.84); sarcopenia was present in 34.63% (SD 12.86) of the patients. Mechanical and pathway analysis were based on five animal studies and 29 clinical reports, showing significantly altered muscle strength and function in 1352 PAD patients [26.49% (SD 17.32) women], aged 67.67 (SD 5.14) years; impaired muscle histology in 192 PAD patients (9.2% (SD 11.22) women), aged 64.3 (SD 0.99) years; +58.63% (SD 25.48) of oxidative stress in 69 PAD patients [16.96% (SD 8.10) women], aged 63.17 (SD 1.43) years; mitochondriopathy in 153 PAD patients [29.39% (SD 28.27) women], aged 63.50 (SD 1.83) years; +15.58% (SD 7.41) of inflammation in 900 PAD patients [40.77% (SD 3.71) women], aged 74.88 (SD 2.76) years; and altered signalling pathways in 51 PAD patients [34.45% (SD 32.23) women], aged 72.25 (SD 5.25) years. Therapeutic approaches analysis was based on seven animal studies and 21 clinical reports. In total, 884 patients followed an exercise therapy, and 18 received an angiogenesis treatment; 30.84% (SD 17.74) were women. Mean ages of patients studied were 66.85 (SD 3.96).

CONCLUSIONS

Sarcopenia and lower extremity PAD have musculoskeletal consequences that directly impair patients' quality of life and prognosis. Although PAD is primarily a vascular disease, all etiological factors of sarcopenia identified so far are present in PAD. Indeed, both sarcopenia and PAD are accompanied by oxidative stress, skeletal muscle mitochondrial impairments, inflammation, inhibition of specific pathways regulating muscle synthesis or protection (i.e. IGF-1, RISK, and SAFE), and activation of molecules associated with muscle degradation. To date, besides revascularization, the best therapeutic strategy includes exercise, but approaches targeting the underlying mechanisms still deserve further studies.

Greater Periaortic Fat Volume at Midlife Is Associated with Slower Gait Speed Later in Life in Women: The SWAN Cardiovascular Fat Ancillary Study

BACKGROUND

Higher perivascular adipose tissue (PVAT) contributes to adverse physiologic alterations in the vascular wall, and thus could potentially limit normal physical function later in life. We hypothesize that higher PVAT volume at midlife is prospectively associated with slower gait speed later in life, independent of overall adiposity and other risk factors.

METHODS

Participants from the Study of Women's Health Across the Nation (SWAN) cardiovascular fat ancillary study were included. PVAT volume around the descending aorta was quantified using existing computed tomography scans at midlife, while gait speed was measured after an average of 10.4 ± 0.7 years.

RESULTS

Two hundred and seventy-six women (aged 51.3 ± 2.8 years at PVAT assessment) were included. Mean gait speed was 0.96 ± 0.21 m/s. Adjusting for study site, race, education level, menopausal status, and length of descending aorta at PVAT assessment, and age, body mass index, difficulty paying for basics, overall health and smoking status at gait speed assessment, a higher midlife PVAT volume was associated with a slower gait speed later in life (p = .03). With further adjustment for presence of any comorbid conditions by the time of gait speed assessment, the association persisted; every 1SD increase in log-PVAT was associated with 3.3% slower gait speed (95% confidence interval: 0.3-6.3%; p = .03).

CONCLUSION

Greater PVAT in midlife women may contribute to poorer physical function in older age supporting a potential role of midlife PVAT in multiple domains of healthy aging. Additional research is needed to fully elucidate the physiologic changes associated with PVAT that may underlie the observed associations.

Muscle fatigability in patients with type 2 diabetes: relation with long-term complications

AIMS

It is unclear whether long-term complications play a role in muscle fatigue characteristic of patients with type 2 diabetes mellitus (T2DM). The purpose of this study was to investigate the association between muscle fatigability and microvascular and macrovascular complications in patients with T2DM.

METHODS

One-hundred forty-six patients with T2DM (80 males, 66 females, aged 66.9 ± 7.9 years) were recruited. Maximal voluntary contraction (MCV) and endurance time (ET, 50% of the MVC) were assessed at the knee extensor muscles with an isometric dynamometer. Univariate and multivariate correlations of ET values with diabetic complications, a wide range of surrogate measures of these sequelae, and cardiovascular risk factors were examined.

RESULTS

A higher muscle fatigability was detected in patients with diabetic peripheral neuropathy (DPN, ET: -32.4%), cardiovascular disease (CVD, ET: -32.1%), retinopathy (ET: -35.8%), and nephropathy (ET: -30.4%). At univariate analysis, muscle fatigability was associated with age, physical activity level, diabetes duration, HbA_1c , systolic blood pressure, albuminuria, eGFR, and several parameters of nervous and vascular function. Multivariate analysis showed that, after adjusting for covariates, ET was independently associated with sensory nerve conduction velocity, vibration perception threshold at malleolus, and ankle-brachial index. In addition, ET values were independently associated with the presence of DPN, CVD, and retinopathy.

CONCLUSIONS

In T2DM, muscle fatigability is associated with presence of DPN, CVD, and retinopathy. Such defect appears to be mediated predominantly by sensory nerve and peripheral vascular dysfunction.

Associations of Weight Change With Changes in Calf Muscle Characteristics and Functional Decline in Peripheral Artery Disease

Background

Among people with lower extremity peripheral artery disease, obesity is associated with faster functional decline than normal weight. The association of weight loss with functional decline in peripheral artery disease is unknown.

Methods and Results

Adults with an ankle‐brachial index <0.90 were identified from Chicago‐area hospitals in 2002–2004. Weight and 6‐minute walk distance were measured annually. Weight change categories were weight loss or gain (≥5 pounds/year at ≥1 visit) or stable (weight change <5 pounds at each visit). Participants reported whether weight loss was “intentional” or “unintentional.” Calf muscle area was measured with computed tomography every 2 years. Associations of weight change with changes in calf muscle area and 6‐minute walk distance were analyzed using mixed‐effects models and adjusted for age, body mass index, ankle‐brachial index, physical activity, and other confounders. Among 389 participants, mean ankle‐brachial index was 0.63±0.16, mean age was 74.5±7.8, and mean body mass index was 28.1±5.1 kg/m². Over 3.23±1.37 years, muscle area declined more in adults with intentional weight loss versus stable or gain (pair‐wise comparisons, P<0.001). Intentional weight loss was associated with less annual decline in 6‐minute walk distance than weight gain (intentional loss, 3.7 m; stable, –14.0 m; gain, −28.5 m; unintentional loss, −20.8 m; pair‐wise comparison intentional loss versus gain, P=0.003).

Conclusions

Despite a greater loss of calf muscle area, adults with peripheral artery disease who intentionally lost ≥5 pounds experienced less functional decline than those who gained weight. A randomized trial is needed to establish whether benefits of weight loss in peripheral artery disease outweigh potential adverse effects.

See Editorial Kokkinidis et al

Exosomes Derived from Human Primed Mesenchymal Stem Cells Induce Mitosis and Potentiate Growth Factor Secretion

Mesenchymal stem cells (MSCs) facilitate functional recovery in numerous animal models of inflammatory and ischemic tissue-related diseases with a growing body of research suggesting that exosomes mediate many of these therapeutic effects. It remains unclear, however, which types of proteins are packaged into exosomes compared with the cells from which they are derived. In this study, using comprehensive proteomic analysis, we demonstrated that human primed MSCs secrete exosomes (pMEX) that are packaged with markedly higher fractions of specific protein subclasses compared with their cells of origin, indicating regulation of their contents. Notably, we found that pMEX are also packaged with substantially elevated levels of extracellular-associated proteins. Fibronectin was the most abundant protein detected, and data established that fibronectin mediates the mitogenic properties of pMEX. In addition, treatment of SHSY5Y cells with pMEX induced the secretion of growth factors known to possess mitogenic and neurotrophic properties. Taken together, our comprehensive analysis indicates that pMEX are packaged with specific protein subtypes, which may provide a molecular basis for their distinct functional properties.

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.

Joint moment strategies during stair descent in patients with peripheral arterial disease and intermittent claudication

OBJECTIVE

To determine the lower limb joint kinetic strategies during stair descent in claudicants with peripheral arterial disease (PAD-IC).

DESIGN

Cross-sectional observation study.

SETTING

University laboratory.

PARTICIPANTS

A total of 22 participants; 10 healthy controls and 12 patients diagnosed with PAD-IC.

MAIN OUTCOME MEASURES

Between-group comparisons of ground reaction force (GRF) and, hip, knee and ankle kinetics during steady-state stair descent.

RESULTS

The claudicating-limb group demonstrated reduced vertical and posterior GRF compared to healthy controls (ES = -1.46 [-2.32,-0.69] and ES = -1.08 [-0.42,-0.26]) as well as demonstrating an greater contribution to support moment from the ankle and trends towards a smaller hip contribution (42 ± 14% vs 28 ± 7%, P = .005 and Hip 16 ± 8% vs 21 ± 11%, P = .056, respectively). A unique sub-group was identified within the PAD-IC cohort demonstrating different hip moment strategies during weight acceptance: a novel hip extensor group (PAD-IC HExt) and stereotypical hip flexor group (PAD-IC HFlex). Compared to both healthy controls and the PAD-IC HFlex groups, the PAD-IC HExt group demonstrated increased hip extensor moment (ES = 3.05 [1.67,4.42] and ES = 3.62 [1.89,5.35]) and reduced knee extensor moment (ES = -2.00 [-3.15,-0.85] and ES = -1.36 [-2.60,-0.11] respectively) during weight acceptance.

CONCLUSIONS

A novel hip extensor strategy was identified in a sub-group of claudicants which acts to reduce the demand on the knee extensors, but not the plantarflexors. Weakness in the knee extensors may prevent redistribution of the task demand, typically seen in older adults in stair descent, away from the functionally limited plantarflexor muscle group. Further investigation into multi-level joint strength and the relationship to functional tasks is warranted to inform targeted intervention programmes.

Peripheral artery disease is associated with frailty in chronic hemodialysis patients

Objectives

The clinical condition of frailty is a common problem in the elderly population. However, the relationship between peripheral artery disease and frailty in hemodialysis patients remains unknown. The aim of this study was to identify the relationships between peripheral artery disease and frailty in Japanese chronic hemodialysis patients.

Methods

A total of 362 chronic hemodialysis patients who regularly visited six institutions were enrolled. To evaluate frailty, the modified Fried’s frailty phenotype adjusted for Japanese were used. Peripheral artery disease was defined as ankle-brachial index <0.9.

Results

Of 362 patients, 62 patients (17.1%) were categorized as peripheral artery disease group and 300 patients (82.9%) as Non-peripheral artery disease group. The prevalence of frailty in the peripheral artery disease group was significantly higher than in the Non-peripheral artery disease group (34% vs. 18%, P = 0.0103). Non-shunt side grip strength was significantly stronger in the Non-peripheral artery disease group (23.6 kg vs. 17.0 kg, P < 0.0001). Thigh circumferences were also significantly larger in the Non-peripheral artery disease group (41.7 cm vs. 39.7 cm, P = 0.0054). A multivariate logistic regression analysis demonstrated that the factors independently associated with peripheral artery disease were as follows: frailty (odds ratio = 2.06, 95% confidence interval 1.09–3.89) and myocardial infarction (odds ratio = 3.74, 95% confidence interval 2.05–6.83).

Conclusions

It is concluded that peripheral artery disease is closely associated with frailty in hemodialysis patients.

Gait kinematics and kinetics are affected more by peripheral arterial disease than by age

Peripheral arterial disease (PAD) produces abnormal gait and disproportionately affects older individuals. The current study investigated PAD gait biomechanics in younger (<65 yr) and older (>/=65 yr) subjects. The study included 61 patients with PAD (31 younger, age: 57.4 +/- 5.3 yr, and 30 older, age: 71.9 +/- 5.2 yr) and 52 nondisabled age-matched control subjects. Patients with PAD were tested during pain-free walking and compared with control subjects. Joint kinematics and kinetics (torques) were compared using a 2 x 2 analysis of variance (groups: patients with PAD vs control subjects, age: younger vs older). Patients with PAD had significantly increased ankle and decreased hip range of motion during the stance phase as well as decreased ankle dorsiflexor torque compared with control subjects. Gait changes in older individuals are largely constrained to time-distance parameters. Joint kinematics and kinetics are significantly altered in patients with PAD during pain-free walking. Symptomatic PAD produces a consistent ambulatory deficit across ages definable by advanced biomechanical analysis. The most important finding of the current study is that gait, in the absence of PAD and other ambulatory comorbidities, does not decline significantly with age based on advanced biomechanical analysis. Therefore, previous studies must be examined in the context of patients with potential PAD being present in the population, and future ambulatory studies must include PAD as a confounding factor when assessing the gait function of elderly individuals.

Low ankle brachial index is associated with the magnitude of impaired walking endurance in patients with heart failure

BACKGROUND

Measurement of the ankle brachial index (ABI) is a simple, noninvasive means of diagnosing peripheral arterial disease, and has been shown to be associated with mortality rate. Here, we examined the association between ABI and physical function in patients with heart failure (HF).

METHODS

The study population consisted of 524 admitted patients (67.2±13.9years, 343 males) with HF. Blood pressure and the ABI were determined by oscillometry. Prior to hospital discharge, ABI, 6-minute walking distance, walking velocity, handgrip strength, quadriceps isometric strength, and standing balance were determined. The 524 patients were divided according to ABI as follows: ABI≤0.90 (low ABI), ABI 0.91 to 0.99 (borderline ABI), and ABI 1.00 to 1.40 (normal ABI).

RESULTS

Lower ABI values were associated with shorter 6-minute walking distance (p trend=0.001), slower walking velocity (p trend=0.023), and poorer standing balance (p trend=0.048). There were no significant associations between ABI and handgrip strength or quadriceps isometric strength. After adjusting for potential confounders, patients with ABI≤0.90 had shorter 6-minute walking distance compared to those with ABI 1.00 to 1.40 (adjusted mean value: 344m vs. 395m, respectively, p<0.001). There were no significant differences in any of the other physical function parameters examined.

CONCLUSIONS

In patients with HF, low ABI is associated with the magnitude of impairment in walking endurance.

The effect of supervised exercise therapy for intermittent claudication on lower limb lean mass

OBJECTIVE

Supervised exercise is currently recommended for the first-line treatment of intermittent claudication based on improvement in walking capacity. However, the promotion of skeletal muscle atrophy by repetitive ischemia-reperfusion caused by treadmill-based programs remains a concern. Because preservation of skeletal muscle mass (SMM) and lean mass (LM) is integral to functional capacity and longevity, this study measured the effect of standard treadmill-based supervised exercise on SMM and regional lower limb LM in patients with intermittent claudication.

METHODS

Patients with calf claudication caused by infrainguinal peripheral artery disease underwent whole-body dual-energy X-ray absorptiometry scanning before and after completion of a 12-week supervised treadmill exercise program. Total body SMM and lower limb LM were measured according to anatomical regions of the lower limb (thigh vs calf) and side of symptoms. Walking performance was assessed using pain-free walking distance and 6-minute walking distance tests.

RESULTS

Thirty-six patients with calf claudication completed exercise training and dual-energy X-ray absorptiometry scanning, allowing analysis of 55 symptomatic and 17 asymptomatic lower limbs. No difference in total body SMM (P = .41) or LM of symptomatic (P = .53) or asymptomatic calves (P = .59) was detected after the program. In contrast, a significant decrease in LM was observed in symptomatic (P = .04) and asymptomatic thighs (P = .005). Pain-free walking distance (P = .001) and the 6-minute walking distance both improved significantly (P = .004) but were not associated with changes in LM.

CONCLUSIONS

Twelve weeks of standard treadmill-training for intermittent calf claudication did not result in loss of calf LM; however, a significant decrease in bilateral thigh LM was observed, even in patients with unilateral symptoms. Further research on optimum exercise modalities and end points are required to determine the pathophysiology and effects of these changes on function and survival.

Frailty and sarcopenia as the basis for the phenotypic manifestation of chronic diseases in older adults

Frailty is a functional status that precedes disability and is characterized by decreased functional reserve and increased vulnerability. In addition to disability, the frailty phenotype predicts falls, institutionalization, hospitalization and mortality. Frailty is the consequence of the interaction between the aging process and some chronic diseases and conditions that compromise functional systems and finally produce sarcopenia. Many of the clinical manifestations of frailty are explained by sarcopenia which is closely related to poor physical performance. Reduced regenerative capacity, malperfusion, oxidative stress, mitochondrial dysfunction and inflammation compose the sarcopenic skeletal muscle alterations associated to the frailty phenotype. Inflammation appears as a common determinant for chronic diseases, sarcopenia and frailty. The strategies to prevent the frailty phenotype include an adequate amount of physical activity and exercise as well as pharmacological interventions such as myostatin inhibitors and specific androgen receptor modulators. Cell response to stress pathways such as Nrf2, sirtuins and klotho could be considered as future therapeutic interventions for the management of frailty phenotype and aging-related chronic diseases.

Six-Minute Walk Test in Renal Failure Patients: Representative Results, Performance Analysis and Perceived Dyspnea Predictors

Objectives

Six-minute walk test in dialysis population hasn’t been consistently evaluated for the isolated impact of renal failure and other predictive factors. We measured six-minute walk distance in patients representative for low level of comorbidity and searched for potentially modifiable predictive factors of performance and dyspnea.

Methods

This was a cross-sectional study with hemodialysis patients (N = 90) and control subjects (N = 140). Main outcome measures: six-minute walk test distance and dyspnea severity using the 10-item Borg scale.

Results

Median distance decreased from 600m below the 6^th decade to 420m in the 8^th decade of age. Dialysis dependence predicted 101.5m shorter distance in the adjusted model that explained 70% of variability in results. Adjusted for significant covariates of age, height and spontaneous gait speed, fat mass (but not lean body mass) and serum total iron binding capacity were significantly associated with distance (95% CI for B coefficients -4.6 to –1.4 m/kg and 0.1 to 5 m/μmol/l, respectively). Serum total iron binding capacity as an explanatory variable was superior to C-reactive protein and albumin. Dialysis dependence, odds ratio (OR) 2.97 (1.11–7.94), spontaneous gait speed, OR 0.08 (0.02–0.41), rate-pressure product, OR 1.15 (1.08–1.23) and hemoglobin, OR 0.95 (0.92–0.98) predicted dyspnea in the adjusted model.

Conclusions

Renal failure without the confounding effect of comorbidity is a significant negative predictor of performance at six-minute walk test and perceived level of dyspnea. Body fat mass and serum total iron binding capacity are the main potentially modifiable predictors of performance, total iron binding capacity being superior to C-reactive protein and albumin. Although hemoglobin is not associated with test performance, it negatively predicts perceived shortness of breath.

Analysis of isokinetic muscle function and postural control in individuals with intermittent claudication

BACKGROUND:

Intermittent claudication (IC) is a debilitating condition that mostly affects elderly people. IC is manifested by a decrease in ambulatory function. Individuals with IC present with motor and sensory nerve dysfunction in the lower extremities, which may lead to deficits in balance.

OBJECTIVE:

This study aimed to measure postural control and isokinetic muscle function in individuals with intermittent claudication.

METHOD:

The study included 32 participants of both genders, 16 IC participants (mean age: 64 years, SD=6) and 16 healthy controls (mean age: 67 years, SD=5), which were allocated into two groups: intermittent claudication group (ICG) and control group (CG). Postural control was assessed using the displacement and velocity of the center of pressure (COP) during the sensory organization test (SOT) and the motor control test (MCT). Muscle function of the flexor and extensor muscles of the knee and ankle was measured by an isokinetic dynamometer. Independent t tests were used to calculate the between-group differences.

RESULTS:

The ICG presented greater displacement (p =0.027) and speed (p =0.033) of the COP in the anteroposterior direction (COPap) during the MCT, as well as longer latency (p =0.004). There were no between-group differences during the SOT. The ICG showed decreased muscle strength and power in the plantar flexors compared to the CG.

CONCLUSION:

Subjects with IC have lower values of strength and muscle power of plantiflexores, as well as changes in postural control in dynamic conditions. These individuals may be more vulnerable to falls than healthy subjects.

Clinical predictors of ventilatory threshold achievement in patients with claudication

PURPOSE

Ventilatory threshold (VT) is considered a clinically important marker of cardiovascular function in several populations, including patients with claudication, because it is related to walking capacity and hemodynamics. The purpose of this study was to identify clinical predictors for VT achievement in patients with intermittent claudication.

METHODS

One hundred and seventy-seven (n = 177) patients with intermittent claudication performed a progressive graded cardiopulmonary treadmill test until maximal claudication pain. Oxygen uptake (V˙O2) was continuously measured during the test, and afterwards, VT was visually detected. Clinical characteristics, demographic data, comorbid conditions, and cardiovascular risk factors were obtained. Patients who achieved and did not achieve VT were compared, as well as the workload that VT occurred in the former group.

RESULTS

VT was achieved in 134 patients (76%), and the mean V˙O2 at VT for these patients was 10.8 ± 2.4 mL·kg(-1)·min(-1). Patients who did not achieve VT presented lower ankle brachial index (ABI), claudication onset time, peak walking time, and V˙O2peak, and the proportion of women was higher compared with patients who achieved VT (P < 0.05). Multiple linear regression analysis identified that sex (b = 0.25, P = 0.002), body mass index (b = -0.18, P = 0.025), peak walking time (b = 0.17, P = 0.044), and ABI (b = 0.23, P = 0.006) were predictors of V˙O2 at VT.

CONCLUSIONS

Forty-three patients (24%) with intermittent claudication did not achieve VT, and these patients were mostly women and those with greater severity of disease. Moreover, in those who reached VT, the predictors of poor VT were female sex, high body mass index, low peak walking time, and low ABI.

Dynamic muscle quality of the plantar flexors is impaired in claudicant patients with peripheral arterial disease and associated with poorer walking endurance

OBJECTIVE

Peripheral arterial disease and intermittent claudication (PAD-IC) negatively affects physical activity and function. There is evidence for plantarflexor muscle dysfunction and weakness; however, the extent to which this dysfunction can be attributed to reduced muscle size or quality, or both, is not yet known. This study investigated whether in vivo plantarflexor muscle quality during static and dynamic contractions is altered by PAD-IC and whether such changes are associated with impaired walking endurance according to initial and absolute claudication distances.

METHODS

The study recruited 22 participants, consisting of 10 healthy controls and 12 claudicant patients with occlusion of the superficial femoral artery (seven unilateral and five bilateral). Muscle quality of the combined gastrocnemius muscles during static contractions was calculated by normalizing the estimated maximal potential muscle force to the physiological cross-sectional area of the lateral and medial gastrocnemius. Muscle quality during dynamic contractions of the combined plantarflexor muscles was calculated as the ratio of peak voluntary concentric plantarflexor power and the summed volume of lateral and medial gastrocnemius.

RESULTS

Dynamic muscle quality was 24% lower in the claudicating-limb and asymptomatic-limb groups compared with controls (P = .017 and P = .023). The differences were most apparent at the highest contraction velocity (180°/s). Dynamic muscle quality was associated with reduced walking endurance (R = 0.689, P = .006 and R = 0.550, P = .042 for initial and absolute claudication distance, respectively). The claudicating-limb group demonstrated a trend toward reduced static muscle quality compared with controls (22%, P = .084). The relative contribution of the soleus muscle to plantarflexion maximum voluntary contraction was significantly higher in the claudicating-limb and asymptomatic-limb groups than in controls (P = .012 and P = .018).

CONCLUSIONS

The muscle strength of the plantarflexors in those with PAD-IC appears to be impaired at high contraction velocities. This may be explained by some reduction in gastrocnemii muscle quality and a greater reliance on the prominently type I-fibered soleus muscle. The reduced dynamic capability of the plantarflexor muscles was associated with disease severity and walking ability; therefore, efforts to improve plantarflexor power through dynamic exercise intervention are vital to maintain functional performance.

Scapular muscle performance in individuals with lateral epicondylalgia

STUDY DESIGN

Descriptive, laboratory-based, cross-sectional study.

OBJECTIVES

To describe scapular musculature strength, endurance, and change in thickness in individuals with unilateral lateral epicondylalgia (LE) compared to the uninvolved limb and the corresponding limb of a matched comparison group.

BACKGROUND

Reported poor long-term outcomes for the nonsurgical management of individuals with LE suggest a less-than-optimal rehabilitation process. Knowledge of scapular muscle function in a working population of individuals with LE may help to further refine conservative management of this condition.

METHODS

Twenty-eight patients with symptomatic LE and 28 controls matched by age and sex were recruited to participate in the study. Strength of the middle trapezius (MT), lower trapezius (LT), and serratus anterior (SA) was measured with a handheld dynamometer. A scapular isometric muscle endurance task was performed in prone. Changes in muscle thickness of the SA and LT were measured with ultrasound imaging. Analysis-of-variance models were used to determine within- and between-group differences.

RESULTS

The involved side of the group with LE had significantly lower values for MT strength (P = .031), SA strength (P<.001), LT strength (P = .006), endurance (P = .003), and change in SA thickness (P = .028) when compared to the corresponding limb of the control group. The involved side of the group with LE had significantly lower strength of the LT (P = .023) and SA (P = .016) when compared to the uninvolved limb; however, these differences were small and of potentially limited clinical significance.

CONCLUSION

When compared to a matched comparison group, there were impairments of scapular musculature strength and endurance in patients with LE, suggesting that the scapular musculature should be assessed and potentially treated in this population. Cause and effect cannot be established, as the weakness of the scapular musculature could be a result of LE.

A review of the relationship between leg power and selected chronic disease in older adults

OBJECTIVE

This review investigates the relationship between leg muscle power and the chronic conditions of osteoarthritis, diabetes mellitus, and cardiovascular disease among older adults. Current literature assessing the impact of chronic disease on leg power has not yet been comprehensively characterized. Importantly, individuals with these conditions have shown improved leg power with training.

METHODS

A search was performed using PubMed to identify original studies published in English from January 1998 to August 2013. Leg power studies, among older adults ≥ 50 years of age, which assessed associations with osteoarthritis, diabetes mellitus, and/or cardiovascular disease were selected. Studies concerning post-surgery rehabilitation, case studies, and articles that did not measure primary results were excluded.

RESULTS

Sixteen studies met inclusion criteria, addressing osteoarthritis (n=5), diabetes mellitus (n=5), and cardiovascular disease (n=6). Studies generally supported associations of lower leg power among older adults with chronic disease, although small sample sizes, cross-sectional data, homogenous populations, varied disease definitions, and inconsistent leg power methods limited conclusions.

CONCLUSIONS

Studies suggest that osteoarthritis, diabetes mellitus, and cardiovascular disease are associated with lower leg power compared to older adults without these conditions. These studies are limited, however, by the heterogeneity in study populations and a lack of standardized measurements of leg power. Future larger studies of more diverse older adults with well-defined chronic disease using standard measures of leg power and interventions to improve leg power in these older adults with chronic disease are needed.

Objective measurement of lower extremity function and quality of life after surgical revascularization for critical lower extremity ischemia

BACKGROUND

Outcomes of revascularization for critical limb ischemia (CLI) have historically been patency, limb salvage, and survival. Functional status and quality of life have not been well described. This study used functional and quality of life assessments to measure patient-centered outcomes after revascularization for CLI.

METHODS

The study observed 18 patients (age, 65 ± 11 years) prospectively before and after lower extremity bypass for CLI. Patients completed the Short Physical Performance Battery, which measures walking speed, leg strength, and balance, as well as performed a 6-minute walk, and calorie expenditure was measured by an accelerometer. Isometric muscle strength was assessed with the Muscle Function Evaluation chair (Metitur, Helsinki, Finland). Quality of life instruments included the 36-Item Short Form Health Survey and the Vascular Quality of Life questionnaire. Patients' preoperative status was compared with 4-month postoperative status.

RESULTS

Muscle Function Evaluation chair measurements of ipsilateral leg strength demonstrated a significant increase in knee flexion from 64 ± 62 N to 135 ± 133 N (P = .038) and nearly significant increase in knee extension from 120 ± 110 N to 186 ± 85 N (P = .062) and ankle plantar flexion from 178 ± 126 N to 267 ± 252 N (P = .078). In the contralateral leg, knee flexion increased from 71 ± 96 N to 149 ± 162 N (P = .028) and knee extension from 162 ± 112 N to 239 ± 158 N (P = .036). Absolute improvements were noted in 6-minute walk distance, daily calorie expenditure, and individual domains and overall Short Physical Performance Battery scores, and upper extremity strength decreased, although none were significant. The Vascular Quality of Life questionnaire captured significant improvement in all individual domains and overall score (P < .015). Significant improvement was noted only for bodily pain (P = .011) on the 36-Item Short Form Health Survey.

CONCLUSIONS

Despite lack of statistical improvement in most functional test results, revascularization for CLI results in improved patient-perceived leg function. Significant improvements in isometric muscle strength may explain the measured improvement in quality of life after revascularization for CLI.

Borderline ankle-brachial index value of 0.91-0.99 is associated with endothelial dysfunction

BACKGROUND

An ankle-brachial index (ABI) value of 0.91-0.99 is considered borderline and associated with an increased risk of cardiovascular events. However, there is no information on the relationship between borderline ABI and endothelial function.

METHODS AND RESULTS

We measured ABI and assessed vascular function by flow-mediated vasodilation (FMD) and nitroglycerin-induced vasodilation in 389 subjects who underwent health examinations. Subjects were divided into 3 groups according to ABI (normal group: 1.00-1.40, borderline group: 0.91-0.99, abnormal group: ≤0.90 or >1.40). FMD was significantly smaller in both the borderline and the abnormal group than in the normal group. There was no significant difference in the vascular responses to nitroglycerin between the normal and borderline groups. Vascular response to nitroglycerin was significantly higher in the normal group than in the abnormal group. Borderline and abnormal ABI values were significantly associated with an increased odds ratio of low tertile of FMD levels, using the normal ABI group as the reference. Multiple logistic regression analysis for FMD revealed that age, sex, hypertension, diabetes mellitus, and borderline ABI independently remained associated with FMD.

CONCLUSIONS

ABI of 0.91-0.99 is associated with endothelial dysfunction. ABI examination is a simple and cost-effective method for obtaining the additional information on the initial step of atherosclerosis beyond the assessment of peripheral artery disease.

Null association between abdominal muscle and calcified atherosclerosis in community-living persons without clinical cardiovascular disease: the multi-ethnic study of atherosclerosis

OBJECTIVE

Lean muscle loss has been hypothesized to explain J-shaped relationships of body mass index (BMI) with cardiovascular disease (CVD), yet associations of muscle mass with CVD are largely unknown. We hypothesized that low abdominal lean muscle area would be associated with greater calcified atherosclerosis, independent of other CVD risk factors.

MATERIALS/METHODS

We investigated 1020 participants from the Multi-Ethnic Study of Atherosclerosis who were free of clinical CVD. Computed tomography (CT) scans at the 4th and 5th lumbar disk space were used to estimate abdominal lean muscle area. Chest and abdominal CT scans were used to assess coronary artery calcification(CAC), thoracic aortic calcification (TAC), and abdominal aortic calcification (AAC).

RESULTS

The mean age was 64±10 years, 48% were female, and mean BMI was 28±5 kg/m2. In models adjusted for demographics, physical activity, caloric intake, and traditional CVD risk factors, there was no inverse association of abdominal muscle mass with CAC (prevalence ratio [PR] 1.02 [95% CI 0.95,1.10]), TAC (PR 1.13 [95% CI 0.92, 1.39]) or AAC (PR 0.99 [95% CI 0.94, 1.04]) prevalence. Similarly, there was no significant inverse relationship between abdominal lean muscle area and CAC, TAC, and AAC severity.

CONCLUSION

In community-living individuals without clinical CVD, greater abdominal lean muscle area is not associated with less calcified atherosclerosis.

Heel-rise test in the assessment of individuals with peripheral arterial occlusive disease

INTRODUCTION

The heel-rise test (HRT) is a clinical instrument relevant to vascular rehabilitation that has been proposed to assess the function of the triceps surae muscle. To use HRT in the assessment of individuals with peripheral arterial occlusive disease (PAOD), its ability to detect differences in the functional performance of patients with PAOD must be verified.

AIM

To verify whether the test is sensitive in differentiating between individuals with PAOD with distinct functional capacities.

MATERIALS AND METHODS

A transversal study in which individuals with PAOD were assessed using the HRT, the Walking Impairment Questionnaire (WIQ), and the Shuttle Walk Test. The following variables were analyzed: number of plantar flexions performed in the HRT (time in seconds) and velocity (plantar flexions per second) when performing plantar flexions up to the point of volunteer fatigue, maximum distance walked in the Shuttle Walk Test, and scores obtained in each WIQ domain.

RESULTS

Twenty-five individuals (14 male) were included in the study, with a mean age of 63.36 ± 9.83 years. The variables number of plantar flexions and time to perform the HRT were sensitive enough to differentiate between distinct functional capacities in individuals with PAOD (P = 0.003 and P = 0.009, respectively). However, this result was not found for the variable of velocity in the HRT. The number of plantar flexions in the HRT was sensitive enough to differentiate individuals of extreme classes on the WIQ domain, stairs (P = 0.008).

CONCLUSION

The HRT can be applied in clinical practice as a valid assessment of the distinct function capacities of individuals with PAOD.

Vitamin D status and functional performance in peripheral artery disease

The clinical implications of low vitamin D in peripheral artery disease (PAD) are unknown. We hypothesized that among individuals with PAD, lower levels of 25-hydroxyvitamin D would be associated with poorer functional performance, more adverse calf muscle characteristics, and poorer peripheral nerve function. Participants were 402 men and women with PAD who underwent measurement of 25-hydroxyvitamin D (DiaSorin radioimmunoassay) along with 6-minute walk testing, measurement of walking velocity at usual and fastest pace, computed tomography-measured calf muscle density, and peripheral nerve conduction velocity (NCV). Among PAD participants, 20.4% had 25-hydroxyvitamin D levels < 30 nmol/L, consistent with deficient vitamin D status. Adjusting for age, sex, and race, lower 25-hydroxyvitamin D levels were associated with poorer 6-minute walk performance (p trend = 0.002), slower usual-paced 4-meter walking velocity (p trend = 0.031), slower fast-paced 4-meter walking velocity (p trend = 0.043), and lower calf muscle density (p trend = 0.031). After additional adjustment for body mass index (BMI) and diabetes, none of these associations remained statistically significant. However, lower levels of 25-hydroxyvitamin D were associated with poorer peroneal NCV (p trend = 0.013) and poorer sural NCV (p trend = 0.039), even after adjusting for age, sex, race, BMI, comorbidities, smoking, physical activity, and other confounders. In conclusion, vitamin D deficiency is common among people with PAD encountered in clinical settings. After adjusting for BMI and diabetes mellitus, we found no significant associations of lower levels of 25-hydroxyvitamin D with poorer functional performance or calf muscle characteristics. Associations of low vitamin D levels with poorer peripheral nerve function require further study.

Low ankle-brachial index is an independent predictor of poor functional outcome in acute cerebral infarction

OBJECTIVE

The ankle-brachial blood pressure index (ABI) is an established clinical test for assessment of peripheral arterial disease and an indicator of generalized atherosclerosis. We investigated whether low ABI is associated with long-term functional outcome in patients with acute cerebral infarction.

METHODS

We included 775 patients with acute cerebral infarction who were admitted within 7 days from stroke onset and had completed an ABI measurement during admission. Poor functional outcome was defined as a modified Rankin Scale of more than 2 at three months from stroke onset. The association between low ABI and poor functional outcome was analyzed using logistic regression analysis.

RESULTS

A low ABI (<0.9) was present in 10.1% of patients. At three months from stroke onset, 16.9% of patients showed poor functional outcome (mRS > 2). After adjusting for conventional cardiovascular risk factors and the presence of cerebral atherosclerosis, a low ABI was independently associated with poor functional outcome (odds ratio 2.523, 95% CI 1.330-4.785, p = 0.005).

CONCLUSIONS

The presence of a low ABI was associated with an increased risk of poor functional outcome in patients with acute cerebral infarction. Screening for low ABI among stroke patients may be necessary to identify individuals at increased risk of poor functional outcome. Proper and individualized treatment for patients with a low ABI may improve long-term functional outcome following acute cerebral infarction.

Calf muscle characteristics, strength measures, and mortality in peripheral arterial disease: a longitudinal study

OBJECTIVES

This study analyzed whether lower calf muscle density and poorer upper and lower extremity strength are associated with higher mortality rates in men and women with peripheral arterial disease (PAD).

BACKGROUND

Men and women with lower extremity PAD have lower calf muscle density and reduced lower extremity strength compared with individuals without PAD.

METHODS

At baseline, participants underwent measurement of calf muscle density with computed tomography in addition to knee extension power and isometric knee extension, plantar flexion, and hand grip strength measures. Participants were followed up annually for up to 4 years. Results were adjusted for age, sex, race, body mass index, ankle-brachial index, smoking, physical activity, and comorbidities.

RESULTS

Among 434 PAD participants, 103 (24%) died during a mean follow-up of 47.6 months. Lower calf muscle density was associated with higher all-cause mortality (lowest density tertile hazard ratio [HR]: 1.80 [95% confidence interval (CI): 1.07 to 3.03], second tertile HR: 0.91 (95% CI: 0.51 to 1.62); highest density tertile HR: 1.00; p trend = 0.020) and higher cardiovascular disease mortality (lowest density tertile HR: 2.39 [95% CI: 0.90 to 6.30], second tertile HR: 0.85 [95% CI: 0.27 to 2.71]; highest density tertile HR: 1.00; p trend = 0.047). Poorer plantar flexion strength (p trend = 0.004), lower baseline leg power (p trend = 0.046), and poorer handgrip (p trend = 0.005) were associated with higher all-cause mortality.

CONCLUSIONS

These data demonstrate that lower calf muscle density and weaker plantar flexion strength, knee extension power, and hand grip were associated with increased mortality in these participants with PAD, independently of the ankle-brachial index and other confounders.

Plaque Characteristics in the Superficial Femoral Artery Correlate with Walking Impairment Questionnaire Scores in Peripheral Arterial Disease: The Walking and Leg Circulation Study (WALCS) III

PURPOSE

We studied associations of magnetic resonance imaging (MRI)-measured plaque area and relative percent lumen reduction in the proximal superficial femoral artery with Walking Impairment Questionnaire (WIQ) scores and quality of life in people with lower extremity peripheral arterial disease (PAD).

METHODS

Four-hundred forty-two participants with PAD underwent cross-sectional imaging of the proximal superficial femoral artery with MRI, and completed the WIQ and the Short-Form-12 mental and physical functioning questionnaires. Questionnaires were scored on a 0-100 scale (100=best). Results adjust for age, sex, race, the ankle brachial index (ABI), comorbidities, and other covariates.

RESULTS

Adjusting for age, sex, race, ABI, comorbidities, and other covariates, higher mean plaque area was associated with poorer WIQ distance scores (1^st quintile (least plaque)-44.8, 2^nd quintile-43.3, 3^rd quintile-38.9, 4^th quintile-34.6, 5^th quintile (greatest plaque)-30.6, p trend <0.001) and poorer WIQ speed scores (1^st quintile-40.6, 2^nd quintile-39.6, 3^rd quintile-39.5, 4^th quintile-32.8, 5^th quintile-33.0, p trend =0.019). Similar associations of higher maximum plaque area, mean lumen reduction, and maximum lumen reduction with poorer WIQ distance and speed scores were observed. Plaque measures were not associated with WIQ stair climbing scores or SF-12 scores.

CONCLUSION

Among participants with PAD, greater plaque burden and smaller lumen area in the proximal superficial femoral artery are associated with poorer walking endurance and slower walking speed as measured by the WIQ, even after adjusting for the ABI.

Higher body mass index is associated with more adverse changes in calf muscle characteristics in peripheral arterial disease

OBJECTIVE

This study investigated whether higher body mass index (BMI) is associated with more adverse lower extremity muscle characteristics at baseline and more adverse changes in muscle over time among participants with lower extremity peripheral arterial disease (PAD).

METHODS

This was a longitudinal, observational study of 425 men and women with PAD and 261 without PAD. Computed tomography was used to measure calf muscle characteristics at baseline and every 2 years. Knee extension isometric strength, power, and 6-minute walk distance were measured at baseline and annually. Baseline BMI (kg/m(2)) categories were ideal (20-25), overweight (>25-30), and obese (>30). Analyses adjust for age, race, sex, ankle brachial index, comorbidities, and other covariates.

RESULTS

At baseline, higher BMI among participants with PAD was associated with greater calf muscle area (ideal BMI: 5181 mm(2); overweight: 5513 mm(2); obese: 5695 mm(2); P = .0009 for trend), higher calf muscle percentage of fat (6.38%, 10.28%, 17.44%, respectively, P < .0001 for trend), lower calf muscle density (P < .0001 for trend), and higher isometric knee extension strength (P = .015 for trend). Among participants with PAD, higher BMI was associated with greater declines in calf muscle area (P = .030 for trend) and greater increases in calf muscle percentage of fat (P = .023 for trend). Among participants without PAD, there were no significant associations of baseline BMI with changes in lower extremity muscle outcomes over time.

CONCLUSIONS

Among PAD participants, higher BMI is associated with greater calf muscle area at baseline. However, higher BMI is associated with more adverse calf muscle density and calf muscle percentage of fat at baseline and greater declines in calf muscle area over time.