Exercise training and peripheral arterial disease

Effects of additional exercise therapy after a successful vascular intervention for people with symptomatic peripheral arterial disease

BACKGROUND

Peripheral arterial disease (PAD) is characterised by obstruction or narrowing of the large arteries of the lower limbs, usually caused by atheromatous plaques. Most people with PAD who experience intermittent leg pain (intermittent claudication) are typically treated with secondary prevention strategies, including medical management and exercise therapy. Lower limb revascularisation may be suitable for people with significant disability and those who do not show satisfactory improvement after conservative treatment. Some studies have suggested that lower limb revascularisation for PAD may not confer significantly more benefits than supervised exercise alone for improved physical function and quality of life. It is proposed that supervised exercise therapy as adjunctive treatment after successful lower limb revascularisation may confer additional benefits, surpassing the effects conferred by either treatment alone.

OBJECTIVES

To assess the effects of a supervised exercise programme versus standard care following successful lower limb revascularisation in people with PAD.

SEARCH METHODS

We searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase, two other databases, and two trial registers, most recently on 14 March 2023.

SELECTION CRITERIA

We included randomised controlled trials which compared supervised exercise training following lower limb revascularisation with standard care following lower limb revascularisation in adults (18 years and older) with PAD.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were maximum walking distance or time (MWD/T) on the treadmill, six-minute walk test (6MWT) total distance, and pain-free walking distance or time (PFWD/T) on the treadmill. Our secondary outcomes were changes in the ankle-branchial index, all-cause mortality, changes in health-related quality-of-life scores, reintervention rates, and changes in subjective measures of physical function. We analysed continuous data by determining the mean difference (MD) and 95% confidence interval (CI), and dichotomous data by determining the odds ratio (OR) with corresponding 95% CI. We used GRADE to assess the certainty of evidence for each outcome.

MAIN RESULTS

We identified seven studies involving 376 participants. All studies involved participants who received either additional supervised exercise or standard care after lower limb revascularisation. The studies' exercise programmes varied, and included supervised treadmill walking, combined exercise, and circuit training. The duration of exercise therapy ranged from six weeks to six months; follow-up time ranged from six weeks to five years. Standard care also varied between studies, including no treatment or advice to stop smoking, lifestyle modifications, or best medical treatment. We classified all studies as having some risk of bias concerns. The certainty of the evidence was very low due to the risk of bias, inconsistency, and imprecision. The meta-analysis included only a subset of studies due to concerns regarding data reporting, heterogeneity, and bias in most published research. The evidence was of very low certainty for all the review outcomes. Meta-analysis comparing changes in maximum walking distance from baseline to end of follow-up showed no improvement (MD 159.47 m, 95% CI -36.43 to 355.38; I2 = 0 %; 2 studies, 89 participants). In contrast, exercise may improve the absolute maximum walking distance at the end of follow-up compared to standard care (MD 301.89 m, 95% CI 138.13 to 465.65; I2 = 0 %; 2 studies, 108 participants). Moreover, we are very uncertain if there are differences in the changes in the six-minute walk test total distance from baseline to treatment end between exercise and standard care (MD 32.6 m, 95% CI -17.7 to 82.3; 1 study, 49 participants), and in the absolute values at the end of follow-up (MD 55.6 m, 95% CI -2.6 to 113.8; 1 study, 49 participants). Regarding pain-free walking distance, we are also very uncertain if there are differences in the mean changes in PFWD from baseline to treatment end between exercise and standard care (MD 167.41 m, 95% CI -11 to 345.83; I2 = 0%; 2 studies, 87 participants). We are very uncertain if there are differences in the absolute values of ankle-brachial index at the end of follow-up between the intervention and standard care (MD 0.01, 95% CI -0.11 to 0.12; I2 = 62%; 2 studies, 110 participants), in mortality rates at the end of follow-up (OR 0.92, 95% CI 0.42 to 2.00; I2 = 0%; 6 studies, 346 participants), health-related quality of life at the end of follow-up for the physical (MD 0.73, 95% CI -5.87 to 7.33; I2 = 64%; 2 studies, 105 participants) and mental component (MD 1.04, 95% CI -6.88 to 8.95; I2 = 70%; 2 studies, 105 participants) of the 36-item Short Form Health Survey. Finally, there may be little to no difference in reintervention rates at the end of follow-up between the intervention and standard care (OR 0.91, 95% CI 0.23 to 3.65; I2 = 65%; 5 studies, 252 participants).

AUTHORS' CONCLUSIONS

There is very uncertain evidence that additional exercise therapy after successful lower limb revascularisation may improve absolute maximal walking distance at the end of follow-up compared to standard care. Evidence is also very uncertain about the effects of exercise on pain-free walking distance, six-minute walk test distance, quality of life, ankle-brachial index, mortality, and reintervention rates. Although it is not possible to confirm the effectiveness of supervised exercise compared to standard care for all outcomes, studies did not report any harm to participants from this intervention after lower limb revascularisation. Overall, the evidence incorporated into this review was very uncertain, and additional evidence is needed from large, well-designed, randomised controlled studies to more conclusively demonstrate the role additional exercise therapy has after lower limb revascularisation in people with PAD.

Cilostazol for peripheral arterial disease - a position paper from the Italian Society for Angiology and Vascular Medicine

Cilostazol is a quinolinone-derivative selective phosphodiesterase inhibitor and is a platelet-aggregation inhibitor and arterial vasodilator for the symptomatic treatment of intermittent claudication (IC). Cilostazol has been shown to improve walking distance for patients with moderate to severe disabling intermittent claudication who do not respond to exercise therapy and who are not candidates for vascular surgical or endovascular procedures. Several studies evaluated the pharmacological effects of cilostazol for restenosis prevention and indicated a possible effect on re-endothelialization mediated by hepatocyte growth factor and endothelial precursor cells, as well as inhibiting smooth muscle cell proliferation and leukocyte adhesion to endothelium, thereby exerting an anti-inflammatory effect. These effects may suggest a potential effectiveness of cilostazol in preventing restenosis and promoting the long-term outcome of revascularization interventions. This review aimed to point out the role of cilostazol in treating patients with peripheral arterial disease, particularly with IC, and to explore its possible role in restenosis after lower limb revascularization.

Six-month effects of supervised exercise on walking ability and health-related factors in peripheral arterial disease: a pilot study

BACKGROUND

In peripheral arterial disease (PAD) patients with intermittent claudication (IC), the combination of aerobic and resistance exercises could counteract muscle loss and attenuate disease progression. This study analyzed the effects of six months of a combined exercise program on walking ability, lower limb body composition, cardiovascular risk factors, and Ankle-Brachial Index (ABI).

METHODS

Twenty-three patients (age 63.2±1.5 years and ABI 0.58±0.07) with PAD and IC were allocated to a control group (CG) or a supervised exercise group (SUP). Ten patients underwent six months of treadmill walking combined with resistance exercises, three times a week. The CG (N.=13) received a recommendation for walking. All patients were measured at baseline (M0), after three months (M3), and six months (M6).

RESULTS

During constant treadmill protocol, the claudication onset time/distance (COT/COD), absolute claudication time/distance (ACT/ACD), and number of pauses of overall patients significantly improved at M3 and M6. Between groups were found significant differences in COT and COD at M6 (P=0.005 and P=0.007, respectively); and in ACT and ACD at M3 (P=0.003 for both) and at M6 (P=0.005 and P=0.005, respectively), with major improvements in the SUP. Over the six months, a significant group effect was found in fat-free mass (P=0.041) and predicted muscle mass (P=0.039) of the lower ABI leg, with greater improvements in the SUP.

CONCLUSIONS

A supervised exercise program that combines aerobic and resistance training improves PAD symptoms and has additional benefits for patients. Patients in the program showed improvements in walking ability, lower-limb body composition, perceived exertion, and heart rate during treadmill walking.

The treatment of chronic anemia in heart failure: a global approach

Chronic anemia is an independent risk factor for mortality in patients with heart failure (HF). Restoring physiological hemoglobin (Hb) levels is essential to increase oxygen transport capacity to tissues and improve cell metabolism as well as physical and cardiac performance. Nutritional deficits and iron deficiency are the major causes of chronic anemia, but other etiologies include chronic kidney disease, inflammatory processes, and unexplained anemia. Hormonal therapy, including erythropoietin (EPO) and anabolic treatment in chronic anemia HF patients, may contribute to improving Hb levels and clinical outcomes. Although preliminary studies showed a beneficial effect of EPO therapy on cardiac efficiency and in HF, more recent studies have not confirmed this positive impact of EPO, alluding to its side effect profile. Physical exercise significantly increases Hb levels and the response of anemia to treatment. In malnourished patients and chronic inflammatory processes, low levels of anabolic hormones, such as testosterone and insulin-like growth factor-1, contribute to the development of chronic anemia. This paper aims to review the effect of nutrition, EPO, anabolic hormones, standard HF treatments, and exercise as regulatory mechanisms of chronic anemia and their cardiovascular consequences in patients with HF.

Exploring telehealth interventions to monitor rehabilitation in patients with peripheral artery disease

Peripheral artery disease is a manifestation of systemic atherosclerosis, and these patients often have claudication pain in the legs during activity. This leads to generally adopting an inactive lifestyle; hence, even small changes in physical activity could reduce the risk of an adverse cardiovascular event. For patients with peripheral artery disease compliance with non-invasive interventions like assistive devices and long-term exercise therapy is important for improved health outcomes. Benefits to patients can only be measured if patients with peripheral artery disease adhere to the intervention and barriers are identified with improved solutions. The effect of mobile health including pedometers and smartphone technological applications in motivating the patient to continue adhering to the intervention and persist in physical activity is a new venture to be explored.

Peripheral arterial disease: A small and large vessel problem

Peripheral arterial disease (PAD) is one clinical manifestation of systemic atherosclerosis and is very common. Despite its prevalence, PAD remains underdiagnosed, undertreated, and understudied. The most common symptom in patients with PAD is intermittent claudication (IC), or pain in the lower extremities with walking or exertion, which is relieved after a short period of rest. Many patients with confirmed PAD are asymptomatic or have symptoms other than IC. Regardless of symptoms, patients with PAD have poor cardiovascular outcomes. PAD has largely been viewed a disease of large vessel atherosclerosis but what is becoming clear is that arterial plaques and occlusions are only one piece of the puzzle. Recent work has shown that abnormalities in the microvasculature contribute to the outcome of patients with PAD. From the perspective of the leg, limitation in blood flow is not the only problem as patients have a myriad of other problems, including muscle fibrosis, neuropathic changes, changes in the cellular respiration machinery and dysfunction of the small vessels that perfuse skeletal muscle and the supporting structures. Supervised exercise training remains one of the most effective tool to treat patients with PAD, however, the mechanisms behind its effectiveness are still being elucidated and use of structured exercise programs is not widespread. Medical therapy to treat systemic atherosclerosis is underutilized in patients with PAD. Invasive therapies are used only when patients with PAD have reached an advanced stage. While invasive strategies are effective in some patients with PAD, these strategies are costly, carry risk, and many patients are not amenable to invasive therapy. Appreciating the complex pathophysiology of PAD will hopefully spur new research and development of effective therapies for PAD.

The Tissue Response to Hypoxia: How Therapeutic Carbon Dioxide Moves the Response toward Homeostasis and Away from Instability

Sustained tissue hypoxia is associated with many pathophysiological conditions, including chronic inflammation, chronic wounds, slow-healing fractures, microvascular complications of diabetes, and metastatic spread of tumors. This extended deficiency of oxygen (O₂) in the tissue sets creates a microenvironment that supports inflammation and initiates cell survival paradigms. Elevating tissue carbon dioxide levels (CO₂) pushes the tissue environment toward "thrive mode," bringing increased blood flow, added O₂, reduced inflammation, and enhanced angiogenesis. This review presents the science supporting the clinical benefits observed with the administration of therapeutic CO₂. It also presents the current knowledge regarding the cellular and molecular mechanisms responsible for the biological effects of CO₂ therapy. The most notable findings of the review include (a) CO₂ activates angiogenesis not mediated by hypoxia-inducible factor 1a, (b) CO₂ is strongly anti-inflammatory, (c) CO₂ inhibits tumor growth and metastasis, and (d) CO₂ can stimulate the same pathways as exercise and thereby, acts as a critical mediator in the biological response of skeletal muscle to tissue hypoxia.

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.

Inhibition of transient receptor potential cation channel 6 promotes capillary arterialization during post-ischaemic blood flow recovery

BACKGROUND AND PURPOSE

Capillary arterialization, characterized by the coverage of pre-existing or nascent capillary vessels with vascular smooth muscle cells (VSMCs), is critical for the development of collateral arterioles to improve post-ischaemic blood flow. We previously demonstrated that the inhibition of transient receptor potential 6 subfamily C, member 6 (TRPC6) channels facilitate contractile differentiation of VSMCs under ischaemic stress. We here investigated whether TRPC6 inhibition promotes post-ischaemic blood flow recovery through capillary arterialization in vivo.

EXPERIMENTAL APPROACH

Mice were subjected to hindlimb ischaemia by ligating left femoral artery. The recovery rate of peripheral blood flow was calculated by the ratio of ischaemic left leg to non-ischaemic right one. The number and diameter of blood vessels were analysed by immunohistochemistry. Expression and phosphorylation levels of TRPC6 proteins were determined by western blotting and immunohistochemistry.

KEY RESULTS

Although the post-ischaemic blood flow recovery is reportedly dependent on endothelium-dependent relaxing factors, systemic TRPC6 deletion significantly promoted blood flow recovery under the condition that nitric oxide or prostacyclin production were inhibited, accompanying capillary arterialization. Cilostazol, a clinically approved drug for peripheral arterial disease, facilitates blood flow recovery by inactivating TRPC6 via phosphorylation at Thr69 in VSMCs. Furthermore, inhibition of TRPC6 channel activity by pyrazole-2 (Pyr2; BTP2; YM-58483) promoted post-ischaemic blood flow recovery in Apolipoprotein E-knockout mice.

CONCLUSION AND IMPLICATIONS

Suppression of TRPC6 channel activity in VSMCs could be a new strategy for the improvement of post-ischaemic peripheral blood circulation.

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.

Effects of molecular weight on intestinal anti-inflammatory activities of β-D-glucan from Ganoderma lucidum

To investigate the influence of molecular weight (Mw) on the anti-inflammatory activity of β-D-glucan from Ganoderma lucidum, ultrasonic irradiation was applied to treat the β-D-glucan (GLP, 2.42 × 106 g/mol) solution to obtain two degraded fractions with molecular weight of 6.53 × 105 g/mol (GLPC) and 3.49 × 104 g/mol (GLPN). Structural analysis proved that the degraded fractions possessed similar repeated units with the original β-D-glucan. The in vitro anti-inflammatory activity studies showed that all fractions could significantly inhibit LPS-induced expression of cytokines including TNF-α, IL-8, MIF and MCP-1 in Caco-2 cells at certain concentrations. Moreover, GLPC and GLPN exhibited better anti-inflammatory activity than GLPC. The intestinal anti-inflammatory activity evaluated by dextran sulfate sodium (DSS)—induced colitis mice model showed that intragastric administration of GLPN (lower Mw fraction) could significantly recover inflamed tissues of mice. Compared with GLP and GLPC, GLPN exhibited stronger ability to inhibit the secretion of pro-inflammatory cytokines (TNF-α, IL-1β, and IL-6). The results revealed that Mw of β-D-glucan influenced its anti-inflammatory activity and decreasing of Mw would improve the activity, which provided evidence for the potential use of β-D-glucan from G. lucidum as anti-colitis ingredients.

Impact of supervised exercise on skeletal muscle blood flow and vascular function measured with MRI in patients with peripheral artery disease

Supervised exercise is a common therapeutic intervention for patients with peripheral artery disease (PAD), however, the mechanism underlying the improvement in claudication symptomatology is not completely understood. The hypothesis that exercise improves microvascular blood flow is herein tested via temporally resolved magnetic resonance imaging (MRI) measurement of blood flow and oxygenation dynamics during reactive hyperemia in the leg with the lower ankle-brachial index. One hundred and forty-eight subjects with PAD were prospectively assigned to standard medical care or 3 mo of supervised exercise therapy. Before and after the intervention period, subjects performed a graded treadmill walking test, and MRI data were collected with Perfusion, Intravascular Venous Oxygen saturation, and T2* (PIVOT), a method that simultaneously quantifies microvascular perfusion, as well as relative oxygenation changes in skeletal muscle and venous oxygen saturation in a large draining vein. The 3-mo exercise intervention was associated with an improvement in peak walking time (64% greater in those randomized to the exercise group at follow-up, P < 0.001). Significant differences were not observed in the MRI measures between the subjects randomized to exercise therapy versus standard medical care based on an intention-to-treat analysis. However, the peak postischemia perfusion averaged across the leg between baseline and follow-up visits increased by 10% (P = 0.021) in participants that were adherent to the exercise protocol (completed >80% of prescribed exercise visits). In this cohort of adherent exercisers, there was no difference in the time to peak perfusion or oxygenation metrics, suggesting that there was no improvement in microvascular function nor changes in tissue metabolism in response to the 3-mo exercise intervention.NEW & NOTEWORTHY Supervised exercise interventions can improve symptomatology in patients with peripheral artery disease, but the underlying mechanism remains unclear. Here, MRI was used to evaluate perfusion, relative tissue oxygenation, and venous oxygen saturation in response to cuff-induced ischemia. Reactive hyperemia responses were measured before and after 3 mo of randomized supervised exercise therapy or standard medical care. Those participants who were adherent to the exercise regimen had a significant improvement in peak perfusion.

Integrative Analysis of Bulk RNA-Seq and Single-Cell RNA-Seq Unveils the Characteristics of the Immune Microenvironment and Prognosis Signature in Prostate Cancer

The immune microenvironment is a culmination of the collaborative effort of immune cells and is important in cancer development. The underlying mechanisms of the tumor immune microenvironment in regulating prostate cancer (PRAD) are unclear. In the current study, 144 natural killer cell-related genes were identified using differential expression, single-sample gene set enrichment analysis, and weighted gene coexpression network analysis. Furthermore, VCL, ACTA2, MYL9, MYLK, MYH11, TPM1, ACTG2, TAGLN, and FLNC were selected as hub genes via the protein-protein interaction network. Based on the expression patterns of the hub genes, endothelial, epithelial, and tissue stem cells were identified as key cell subpopulations, which could regulate PRAD via immune response, extracellular signaling, and protein formation. Moreover, 27 genes were identified as prognostic signatures and used to construct the risk score model. Receiver operating characteristic curves revealed the good performance of the risk score model in both the training and testing datasets. Different chemotherapeutic responses were observed between the low- and high-risk groups. Additionally, a nomogram based on the risk score and other clinical features was established to predict the 1-, 3-, and 5-year progression-free interval of patients with PRAD. This study provides novel insights into the molecular mechanisms of the immune microenvironment and its role in the pathogenesis of PARD. The identification of key cell subpopulations has a potential therapeutic and prognostic use in PRAD.

Connecting the past to the present: A historical review of exercise training for peripheral artery disease

Peripheral artery disease (PAD), a prevalent manifestation of atherosclerosis, is associated with increased cardiovascular morbidity and mortality as well as decreased functional ability. Exercise training for PAD is acknowledged to be a highly effective treatment, which improves walking ability and cardiovascular risk. The historical development of this treatment has not been the focus of a report. Therefore, we present a historical review of research on exercise training for PAD. Overall, this body of knowledge has provided strong evidence of the efficacy of supervised exercise training (SET) to improve walking ability for patients with claudication due to PAD. SET, using intermittent bouts of walking exercise to moderate claudication pain on a treadmill, is considered the most efficacious mode of exercise to improve walking ability in patients with claudication. This compelling evidence published over the past 60 years was evaluated by the Centers for Medicare & Medicaid Services in 2017, which culminated in a national coverage determination for SET to improve symptomatic PAD. Future directions include determining optimal delivery strategies for SET and further elucidation of the mechanisms of improvement in walking ability resulting from SET. In addition, alternative forms of exercise should be evaluated and effective home- and community-based exercise interventions should be assessed. There is an enormous need to increase the inclusion of women and racial and ethnic minority groups in studies. It is to be hoped that researchers will continue with new innovative research and persistence in the treatment of claudication due to PAD.

Influence of Epoch Length and Recording Site on the Relationship Between Tri-Axial Accelerometry-Derived Physical Activity Levels and Structural, Functional, and Hemodynamic Properties of Central and Peripheral Arteries

Background

It remains to be established to what extent physical activity (PA) levels among individuals are independently associated with deviations from the “optimal” state of the arterial system. Accelerometers have been proposed as means to obtain reliable, objective, and more comprehensive data of PA. Decisions at the time of data collection/processing could influence the association between accelerometry-derived indices and arterial properties.

Objectives

(i) To identify to what extent the strength of association between arterial properties and accelerometer-derived indices depend on the recording site and/or the epoch length; (ii) to determine whether some arterial characteristics (hemodynamic vs. structural vs. functional) or regions (elastic vs. transitional vs. muscular arteries; central vs. peripheral) have higher levels of association with accelerometry-derived indices.

Methods

Physical activity (PA), cardiovascular risk factors (CRFs), and cardiovascular properties were evaluated in 60 volunteers (general population; age: 23–62 years; women: 43%). PA was measured daily for 7 days (free-living situation; triaxial-accelerometers ActiGraph-GT3X+; hip and wrist; “Worn-to-wrist” option) and raw data was converted at epoch lengths of 1, 5, 10, 30, and 60-s. PA-related energy expenditure, daily time in moderate-to-vigorous PA, steps/minute, and counts-per-minute for vector magnitude were calculated. The cardiovascular evaluation included hemodynamic (central and peripheral pressure), structural (diameters and intima-media thickness), and functional (local and regional stiffness) parameters of carotids, femoral, and brachial arteries, and carotid-femoral and carotid-radial pathways. Arterial z-scores were obtained using age-related equations derived from healthy participants not exposed to CRFs (n = 1,688; age: 2–84 years; female: 51.2%) to evaluate at which degree each parameter deviates from the “optimal” value.

Methods

In general, hip recordings outperformed those obtained on the wrist regarding the strength of association with arterial parameters. Accelerometer-derived indices and their association with arterial properties vary depending on the recording site and epoch length. PA indices are stronger associated with functional (local) than structural variables and with central than peripheral arteries.

Conclusions

Regardless of the PA index, there were independent associations with central artery characteristics, which reinforces that these territories would be the most related to PA levels. Differences in data acquisition and processing could lead to differences in conclusions when addressing the association between accelerometer-derived indices and the cardiovascular system.

Electromagnetic field exposure as a plausible approach to enhance the proliferation and differentiation of mesenchymal stem cells in clinically relevant scenarios

Mesenchymal stem/stromal cell (MSC)‍-based therapy has been regarded as one of the most revolutionary breakthroughs in the history of modern medicine owing to its myriad of immunoregulatory and regenerative properties. With the rapid progress in the fields of osteo- and musculoskeletal therapies, the demand for MSC-based treatment modalities is becoming increasingly prominent. In this endeavor, researchers around the world have devised new and innovative techniques to support the proliferation of MSCs while minimizing the loss of hallmark features of stem cells. One such example is electromagnetic field (EMF) exposure, which is an alternative approach with promising potential. In this review, we present a critical discourse on the efficiency, practicability, and limitations of some of the relevant methods, with insurmountable evidence backing the implementation of EMF as a feasible strategy for the clinically relevant expansion of MSCs.

Systems biology of angiogenesis signaling: Computational models and omics

Angiogenesis is a highly regulated multiscale process that involves a plethora of cells, their cellular signal transduction, activation, proliferation, differentiation, as well as their intercellular communication. The coordinated execution and integration of such complex signaling programs is critical for physiological angiogenesis to take place in normal growth, development, exercise, and wound healing, while its dysregulation is critically linked to many major human diseases such as cancer, cardiovascular diseases, and ocular disorders; it is also crucial in regenerative medicine. Although huge efforts have been devoted to drug development for these diseases by investigation of angiogenesis‐targeted therapies, only a few therapeutics and targets have proved effective in humans due to the innate multiscale complexity and nonlinearity in the process of angiogenic signaling. As a promising approach that can help better address this challenge, systems biology modeling allows the integration of knowledge across studies and scales and provides a powerful means to mechanistically elucidate and connect the individual molecular and cellular signaling components that function in concert to regulate angiogenesis. In this review, we summarize and discuss how systems biology modeling studies, at the pathway‐, cell‐, tissue‐, and whole body‐levels, have advanced our understanding of signaling in angiogenesis and thereby delivered new translational insights for human diseases.

This article is categorized under:

Cardiovascular Diseases > Computational Models

Cancer > Computational Models

Therapy of Pseudoxanthoma Elasticum: Current Knowledge and Future Perspectives

Pseudoxanthoma elasticum (PXE) is a rare, genetic, metabolic disease with an estimated prevalence of between 1 per 25,000 and 56,000. Its main hallmarks are characteristic skin lesions, development of choroidal neovascularization, and early-onset arterial calcification accompanied by a severe reduction in quality-of-life. Underlying the pathology are recessively transmitted pathogenic variants of the ABCC6 gene, which results in a deficiency of ABCC6 protein. This results in reduced levels of peripheral pyrophosphate, a strong inhibitor of peripheral calcification, but also dysregulation of blood lipids. Although various treatment options have emerged during the last 20 years, many are either already outdated or not yet ready to be applied generally. Clinical physicians often are left stranded while patients suffer from the consequences of outdated therapies, or feel unrecognized by their attending doctors who may feel uncertain about using new therapeutic approaches or not even know about them. In this review, we summarize the broad spectrum of treatment options for PXE, focusing on currently available clinical options, the latest research and development, and future perspectives.

Diffusion tensor imaging indices of acute muscle damage are augmented after exercise in peripheral arterial disease

PURPOSE

Although it is known that peripheral arterial disease (PAD) is associated with chronic myopathies, the acute muscular responses to exercise in this population are less clear. This study used diffusion tensor imaging (DTI) to compare acute exercise-related muscle damage between PAD patients and healthy controls.

METHODS

Eight PAD patients and seven healthy controls performed graded plantar flexion in the bore of a 3T MRI scanner. Exercise began at 2 kg and increased by 2 kg every 2 min until failure, or completion of 10 min of exercise. DTI images were acquired from the lower leg pre- and post-exercise, and were analyzed for mean diffusivity, fractional anisotropy (FA), and eigenvalues 1-3 (λ1-3) of the medial gastrocnemius (MG) and tibialis anterior (TA).

RESULTS

Results indicated a significant leg by time interaction for mean diffusivity, explained by a significantly greater increase in diffusivity of the MG in the most affected legs of PAD patients (11.1 × 10-4 ± 0.5 × 10-4 mm2/s vs. 12.7 × 10-4 ± 1.2 × 10-4 mm2/s at pre and post, respectively, P = 0.02) compared to healthy control subjects (10.8 × 10-4 ± 0.3 × 10-4 mm2/s vs. 11.2 × 10-4 ± 0.5 × 10-4 mm2/s at pre and post, respectively, P = 1.0). No significant differences were observed for the TA, or λ1-3 (all P ≥ 0.06). Moreover, no reciprocal changes were observed for FA in either group (all P ≥ 0.29).

CONCLUSION

These data suggest that calf muscle diffusivity increases more in PAD patients compared to controls after exercise. These findings are consistent with the notion that acute exercise results in increased muscle damage in PAD.

A Systematic Review of Exercise Prescription in Patients with Intermittent Claudication: Does Pain Matter?

BACKGROUND

Current guidelines for intermittent claudication advocate exercise at moderate to maximal claudication pain. However, adherence rates to supervised exercise programmes (SEP) remain poor and claudication pain is a contributing factor. Limited evidence suggests that moderate or pain-free exercise may be just as beneficial and may be better tolerated. However, it remains unclear what 'level' of claudication pain is optimal for improving functional outcomes. We therefore conducted a systematic review to synthesise the evidence for exercise prescribed at different levels of claudication pain.

METHODS

The CENTRAL, MEDLINE, Embase and CINAHL databases were searched up to October 2020. Randomized controlled trials (RCTs) that directly compared at least 2 different intensities of claudication pain were included. Outcome measures included walking performance, adherence, quality of life and vascular function.

RESULTS

Of 1,543 search results, 2 studies were included. Maximal walking distance improved by 100-128% in the moderate-pain SEP groups, and by 77-90% in the pain-free SEP groups. Importantly, there were no significant differences between the moderate-pain and pain-free SEP groups in either study for improvements in walking performance, though comparison to a maximal-pain SEP group was not made.

CONCLUSIONS

The efficacy of SEPs for patients with intermittent claudication is irrefutable, though there is no consensus on the optimal level of pain. Therefore, adequately powered RCTs are required to compare the effect of pain-free SEPs, moderate-pain SEPs and maximal-pain SEPs on functional outcomes. (PROSPERO ID: CRD42020213684).

Gut Microbiota: A Novel Regulator of Cardiovascular Disease and Key Factor in the Therapeutic Effects of Flavonoids

Cardiovascular disease is the main cause of death worldwide, and traditional cardiovascular risk factors cannot fully explain the occurrence of the disease. In recent years, the relationship between gut microbiota and its metabolites and cardiovascular disease has been a hot study topic. The changes in gut microbiota and its metabolites are related to the occurrence and development of atherosclerosis, myocardial infarction, heart failure, and hypertension. The mechanisms by which gut microbiota and its metabolites influence cardiovascular disease have been reported, although not comprehensively. Additionally, following ingestion, flavonoids are decomposed into phenolic acids that are more easily absorbed by the body after being processed by enzymes produced by intestinal microorganisms, which increases flavonoid bioavailability and activity, consequently affecting the onset of cardiovascular disease. However, flavonoids can also inhibit the growth of harmful microorganisms, promote the proliferation of beneficial microorganisms, and maintain the balance of gut microbiota. Hence, it is important to study the relationship between gut microbiota and flavonoids to elucidate the protective effects of flavonoids in cardiovascular diseases. This article will review the role and mechanism of gut microbiota and its metabolites in the occurrence and development of atherosclerosis, myocardial infarction, heart failure, and hypertension. It also discusses the potential value of flavonoids in the prevention and treatment of cardiovascular disease following their transformation through gut microbiota metabolism.

The role and mechanism of citrus flavonoids in cardiovascular diseases prevention and treatment

Cardiovascular diseases (CVDs) have been ranked as the leading cause of death in the world, whose global incidence is increasing year by year. Citrus, one of the most popular fruits in the world, is rich in flavonoids. Citrus flavonoids attract special attention due to a variety of biological activities, especially in the prevention and treatment of CVDs. The research progress of citrus flavonoids on CVDs have been constantly updated, but relatively fragmented, which needed to be systematically summarized. Hence, the recent research about citrus flavonoids and CVDs were reviewed, including the types and in vivo processes of citrus flavonoids, epidemiology study and mechanism on prevention and treatment of CVDs by citrus flavonoids. This review would provide a theoretical basis for the citrus flavonoids research and a new idea in the citrus industry development and application.

Considerations for Implementation of an Ankle-Foot Orthosis to Improve Mobility in Peripheral Artery Disease

OBJECTIVE

To explore the perceptions of wearing an ankle-foot orthosis (AFO) in patients with peripheral artery disease (PAD) who did and did not adopt the AFO intervention. This follows a clinical trial of the effectiveness of an AFO in improving walking distances for patients with PAD-related claudication.

DESIGN

A randomized crossover trial of standard of care and an AFO for 3 months. Semistructured interviews were conducted 1.5 months into the AFO intervention to understand acceptability, demand, implementation, and practicality. Data were analyzed using a summative content analysis approach.

SETTING

Vascular surgery clinic and biomechanics research laboratory.

PARTICIPANTS

Patients (N=15; male, 100%; age, 71.9±.6.7y; body mass index [calculated as weight in kilograms divided by height in meters squared], 29.0±.5.5; ankle brachial index: AFO intervention withdrawal, 0.543; AFO intervention completion, 0.740) with claudication completed the study, and 6 withdrew prior to intervention completion.

INTERVENTIONS

A certified orthotist fit participants with an AFO that was worn for 3 months.

MAIN OUTCOME MEASURES

Qualitative analysis of the semistructured interviews.

RESULTS

Key differences were reported between AFO intervention completion and AFO intervention withdrawal. Six of 14 of AFO intervention completion participants described their initial reactions to the AFO as negative vs 3 of 6 AFO intervention withdrawal participants. Only 5 of 15 AFO intervention completion participants reported minimal use of the AFO compared with 5 of 6 AFO intervention withdrawal participants. The AFO intervention withdrawal group reported higher levels of physical discomfort with the use of the AFO (4/6 vs 7/15) and preexisting health issues becoming a barrier to the use of the AFO (3/6 vs 5/15). Positive aspects reported included ease in standing and walking for AFO intervention withdrawal (4/6) and AFO intervention completion groups (13/15) as well as walking straighter and longer with less pain for AFO intervention withdrawal (3/6) and AFO intervention completion groups (9/15).

CONCLUSIONS

Patients withdrawing prior to completion of AFO intervention tended to have more negative perceptions, more comorbidities, and more physical discomfort than those completing the intervention. Both groups reported positive aspects of the AFO. Implementation studies are needed to address barriers to AFO adoption.

Platelet releasate normalises the compromised muscle regeneration in a mouse model of hyperlipidaemia

NEW FINDINGS

What is the central question of this study? What is the impact of obesity-independent hyperlipidaemia on skeletal muscle stem cell function of ApoE-deficient (ApoE^-/- ) mice? What is the main finding and its importance? Compromised muscle stem cell function accounts for the impaired muscle regeneration in hyperlipidaemic ApoE^-/- mice. Importantly, impaired muscle regeneration is normalised by administration of platelet releasate.

ABSTRACT

Muscle satellite cells are important stem cells for skeletal muscle regeneration and repair after injury. ApoE-deficient mice, an established mouse model of hyperlipidaemia and atherosclerosis, show evidence of oxidative stress-induced lesions and fat infiltration in skeletal muscle followed by impaired repair after injury. However, the mechanisms underpinning attenuated muscle regeneration remain to be fully defined. Key to addressing the latter is to understand the properties of muscle stem cells from ApoE-deficient mice and their myogenic potential. Muscle stem cells from ApoE-deficient mice were cultured both ex vivo (on single fibres) and in vitro (primary myoblasts) and their myogenic capacity was determined. Skeletal muscle regeneration was studied on days 5 and 10 after cardiotoxin injury. ApoE-deficient muscle stem cells showed delayed activation and differentiation on single muscle fibres ex vivo. Impaired proliferation and differentiation profiles were also evident on isolated primary muscle stem cells in culture. ApoE-deficient mice displayed impaired skeletal muscle regeneration after acute injury in vivo. Administration of platelet releasate in ApoE-deficient mice reversed the deficits of muscle regeneration after acute injury to wild-type levels. These findings indicate that muscle stem cell myogenic potential is perturbed in skeletal muscle of a mouse model of hyperlipidaemia. We propose that platelet releasate could be a therapeutic intervention for conditions with associated myopathy such as peripheral arterial disease.

Hypoxia induces de novo formation of cerebral collaterals and lessens the severity of ischemic stroke

Pial collaterals provide protection in stroke. Evidence suggests their formation late during gestation (collaterogenesis) is driven by reduced oxygen levels in the cerebral watersheds. The purpose of this study was to determine if collaterogenesis can be re-activated in the adult to induce formation of additional collaterals ("neo-collateral formation", NCF). Mice were gradually acclimated to reduced inspired oxygen (FIO₂) and maintained at 12, 10, 8.5 or 7% for two-to-eight weeks. Hypoxemia induced "dose"-dependent NCF and remodeling of native collaterals, and decreased infarct volume after permanent MCA occlusion. In contrast, no formation occurred of addition collateral-like intra-tree anastomoses, PComs, or branches within the MCA tree. Hypoxic NCF, remodeling and infarct protection were durable, i.e. retained for at least six weeks after return to normoxia. Hypoxia increased expression of Hif2α, Vegfa, Rabep2, Angpt2, Tie2 and Cxcr4. Neo-collateral formation was abolished in mice lacking Rabep2, a novel gene involved in VEGFA→Flk1 signaling and required for formation of collaterals during development, and inhibited by knockdown of Vegfa, Flk1 and Cxcr4. Rabep2-dependent NCF was also induced by permanent MCA occlusion. This is the first report that hypoxia induces new pial collaterals to form. Hypoxia- and occlusion-induced neo-collateral formation provide models to study collaterogenesis in the adult.

Digital processing of ultrasound images on dilated blood vessels from diabetic patients

Introduction Peripheral arterial disease (PAD) is a fairly common degenerative vascular condition in diabetic patients that leads to inadequate blood flow (BF), this disease is mainly due to atherosclerosis that causes chronic narrowing of arteries, which can precipitate acute thrombotic events. In patients with diabetes, atherosclerosis is the main reason for reducing life expectancy, as long as diabetic nephropathy and retinopathy are the largest contributors to end-stage renal disease and blindness, respectively. Objective This was an assessment of dilatation of the blood vessels on diabetic patients vs. healthy volunteers by using digital processing of imaging’s. Materials and Methods The study subject was ultrasound imaging processing of blood vessels dilation on low extremities of diabetic patients, the results were compared with ultrasound images of healthy subjects. Results The digital images processing suggests that there is a significant difference among images experimental of the diabetic group and healthy volunteers’ images, the control group. Discussion The digital imaging processing performed in the Matlab platform is an adequate procedure for blood vessels dilation analysis of the ultrasound images taken from the lower extremities in diabetic patients.

Modes of exercise training for intermittent claudication

BACKGROUND

According to international guidelines and literature, all patients with intermittent claudication should receive an initial treatment of cardiovascular risk modification, lifestyle coaching, and supervised exercise therapy. In the literature, supervised exercise therapy often consists of treadmill or track walking. However, alternative modes of exercise therapy have been described and yielded similar results to walking. This raises the following question: which exercise mode produces the most favourable results? This is the first update of the original review published in 2014.

OBJECTIVES

To assess the effects of alternative modes of supervised exercise therapy compared to traditional walking exercise in patients with intermittent claudication.

SEARCH METHODS

The Cochrane Vascular Information Specialist searched the Cochrane Vascular Specialised Register, CENTRAL, MEDLINE, Embase and CINAHL databases and World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov trials registers to 4 March 2019. We also undertook reference checking, citation searching and contact with study authors to identify additional studies. No language restriction was applied.

SELECTION CRITERIA

We included parallel-group randomised controlled trials comparing alternative modes of exercise training or combinations of exercise modes with a control group of supervised walking exercise in patients with clinically determined intermittent claudication. The supervised walking programme needed to be supervised at least twice a week for a consecutive six weeks of training.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, extracted data, and assessed the risk of bias for each study. As we included studies with different treadmill test protocols and different measuring units (metres, minutes, or seconds), the standardised mean difference (SMD) approach was used for summary statistics of mean walking distance (MWD) and pain-free walking distance (PFWD). Summary estimates were obtained for all outcome measures using a random-effects model. We used the GRADE approach to assess the certainty of the evidence.

MAIN RESULTS

For this update, five additional studies were included, making a total of 10 studies that randomised a total of 527 participants with intermittent claudication (IC). The alternative modes of exercise therapy included cycling, lower-extremity resistance training, upper-arm ergometry, Nordic walking, and combinations of exercise modes. Besides randomised controlled trials, two quasi-randomised trials were included. Overall risk of bias in included studies varied from high to low. According to GRADE criteria, the certainty of the evidence was downgraded to low, due to the relatively small sample sizes, clinical inconsistency, and inclusion of three studies with risk of bias concerns. Overall, comparing alternative exercise modes versus walking showed no clear differences for MWD at 12 weeks (standardised mean difference (SMD) -0.01, 95% confidence interval (CI) -0.29 to 0.27; P = 0.95; 6 studies; 274 participants; low-certainty evidence); or at the end of training (SMD -0.11, 95% CI -0.33 to 0.11; P = 0.32; 9 studies; 412 participants; low-certainty evidence). Similarly, no clear differences were detected in PFWD at 12 weeks (SMD -0.01, 95% CI -0.26 to 0.25; P = 0.97; 5 studies; 249 participants; low-certainty evidence); or at the end of training (SMD -0.06, 95% CI -0.30 to 0.17; P = 0.59; 8 studies, 382 participants; low-certainty evidence). Four studies reported on health-related quality of life (HR-QoL) and three studies reported on functional impairment. As the studies used different measurements, meta-analysis was only possible for the walking impairment questionnaire (WIQ) distance score, which demonstrated little or no difference between groups (MD -5.52, 95% CI -17.41 to 6.36; P = 0.36; 2 studies; 96 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

This review found no clear difference between alternative exercise modes and supervised walking exercise in improving the maximum and pain-free walking distance in patients with intermittent claudication. The certainty of this evidence was judged to be low, due to clinical inconsistency, small sample size and risk of bias concerns. The findings of this review indicate that alternative exercise modes may be useful when supervised walking exercise is not an option. More RCTs with adequate methodological quality and sufficient power are needed to provide solid evidence for comparisons between each alternative exercise mode and the current standard of supervised treadmill walking. Future RCTs should investigate outcome measures on walking behaviour, physical activity, cardiovascular risk, and HR-QoL, using standardised testing methods and reporting of outcomes to allow meaningful comparison across studies.

Effects of Valsartan on Restenosis in Patients with Arteriosclerosis Obliterans of the Lower Extremities Undergoing Interventional Therapy: A Prospective, Randomized, Single-Blind Trial

BACKGROUND The aim of this study was to further clarify the effects of valsartan on restenosis in patients with arteriosclerosis obliterans of the lower extremities. MATERIAL AND METHODS Patients with arteriosclerosis obliterans of the lower extremities undergoing continuous stent implantation in the superficial femoral artery were enrolled and randomly divided into an ARB group and a control group. Patients in the ARB group received valsartan orally in a single-blind manner and were followed up for 6 months. An evaluation was performed based on the criteria for clinical efficacies designed by the Committee of Vascular Disease, Chinese Association of Integrative Medicine. The total clinical effective rate was calculated, and ankle brachial index (ABI) of the patients was assessed. The concentrations of interleukin-6 (IL-6) and high-sensitivity C-reactive protein (hs-CRP) were measured using enzyme-linked immunosorbent assay. The in-stent restenosis of patients was examined by angiography. RESULTS One patient in the control group died due to acute cerebral hemorrhage 4 months after enrollment, and 1 patient was lost to follow-up due to acute myocardial infarction during follow-up 5 months after enrollment. Age, sex, Fontaine stage, and underlying diseases were comparable between the 2 groups. Hs-CRP (3.93±1.43) and IL-6 (11.26±2.29) levels were significant different in the ARB group compared with the control group. The postoperative follow-up showed that ABI was 0.98±0.20 in the ARB group and 0.62±0.48 in the control group. CONCLUSIONS Valsartan inhibited the increase in hs-CRP and IL-6 levels, improved clinical efficacies, increased ABI, and decreased the restenosis rate after the interventional therapy in patients with arteriosclerosis obliterans of the lower extremities.

Telephone health coaching with exercise monitoring using wearable activity trackers (TeGeCoach) for improving walking impairment in peripheral artery disease: study protocol for a randomised controlled trial and economic evaluation

INTRODUCTION

Peripheral artery disease (PAD) is the third most prevalent cardiovascular disease worldwide, with smoking and diabetes being the strongest risk factors. The most prominent symptom is leg pain while walking, known as intermittent claudication. To improve mobility, first-line treatment for intermittent claudication is supervised exercise programmes, but these remain largely unavailable and economically impractical, which has led to the development of structured home-based exercise programmes. This trial aims to determine the effectiveness and cost advantage of TeGeCoach, a 12-month long home-based exercise programme, compared with usual care of PAD. It is hypothesised that TeGeCoach improves walking impairment and lowers the need of health care resources that are spent on patients with PAD.

METHODS AND ANALYSIS

The investigators conduct a prospective, pragmatic randomised controlled clinical trial in a health insurance setting. 1760 patients diagnosed with PAD at Fontaine stage II are randomly assigned to either TeGeCoach or care-as-usual. TeGeCoach consists of telemonitored intermittent walking exercise with medical supervision by a physician and telephone health coaching. Participants allocated to the usual care group receive information leaflets and can access supervised exercise programmes, physical therapy and a variety of programmes for promoting a healthy lifestyle. The primary outcome is patient reported walking ability based on the Walking Impairment Questionnaire. Secondary outcome measures include quality of life, health literacy and health behaviour. Claims data are used to collect total health care costs, healthcare resource use and (severe) adverse events. Outcomes are measured at baseline, 12 and 24 months.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the Medical Association Hamburg. Findings are disseminated through peer-reviewed journals, reports to the funding body, conference presentations and media press releases. Data from this trial are made available to the public and researchers upon reasonable request.NCT03496948 (www.clinicaltrials.gov), Pre-results.

Effects of heated water-based versus land-based exercise training on vascular function in individuals with peripheral artery disease

Peripheral artery disease (PAD) is an atherosclerotic disease that is associated with poor vascular function, walking impairment, and reduced quality of life. Land-based exercise therapy (LBET) is frequently recommended to improve walking and reduce symptoms. Recently, evidence has suggested that heated-water exercise therapy (HWET) is an effective intervention for PAD. However, the efficacy of LBET versus HWET in PAD patients had not been elucidated. Therefore, we sought to compare effects of LBET with HWET on cardiovascular function, exercise tolerance, physical function, and body composition in PAD patients. PAD patients (n = 53) were recruited and randomly assigned to a LBET group (n = 25) or HWET group (n = 28). The LBET group performed treadmill walking, whereas the HWET group performed walking in heated water for 12 wk. Leg (legPWV) and brachial-to-ankle arterial stiffness (baPWV), blood pressure (BP), ankle-brachial index (ABI), 6-min walking distance (6MWD), claudication onset time (COT), physical function, and body composition were assessed before and after 12 wk. There were significant group-by-time interactions (P < 0.05) for legPWV, BP, 6MWD, COT, body composition, and resting metabolic rate (RMR). Both groups significantly reduced (P < 0.05) legPWV, BP, and body fat percentage, and HWET measures were significantly lower than LBET measures. Both groups significantly increased 6MWD, COT, and RMR, and HWET group measures were significantly greater than LBET measures. A time effect was noted for baPWV reduction in both groups (P < 0.05). These results suggest that both LBET and HWET improve cardiovascular function, exercise tolerance, and body composition, and HWET showed considerably greater improvements compared with LBET in patients with PAD.NEW & NOTEWORTHY The results of this study reveal for the first time that although land-based exercise therapy is effective for reducing arterial stiffness and blood pressure in patients with peripheral artery disease (PAD), heated-water exercise therapy demonstrates greater benefits on vascular function. The greater improvements in muscular strength, time to onset of claudication, and exercise tolerance after heated-water exercise therapy may have clinical implications for improving quality of life in patients with PAD. The heated-water exercise therapy intervention demonstrated relatively higher exercise training adherence (∼88%) compared with the land-based exercise intervention (∼81%).

Beneficial Effect of Ubiquinol on Hematological and Inflammatory Signaling during Exercise

Strenuous exercise (any activity that expends six metabolic equivalents per minute or more causing sensations of fatigue and exhaustion to occur, inducing deleterious effects, affecting negatively different cells), induces muscle damage and hematological changes associated with high production of pro-inflammatory mediators related to muscle damage and sports anemia. The objective of this study was to determine whether short-term oral ubiquinol supplementation can prevent accumulation of inflammatory mediators and hematological impairment associated to strenuous exercise. For this purpose, 100 healthy and well-trained firemen were classified in two groups: Ubiquinol (experimental group), and placebo group (control). The protocol was two identical strenuous exercise tests with rest period between tests of 24 h. Blood samples were collected before supplementation (basal value) (T1), after supplementation (T2), after first physical exercise test (T3), after 24 h of rest (T4), and after second physical exercise test (T5). Hematological parameters, pro- and anti-inflammatory cytokines and growth factors were measured. Red blood cells (RBC), hematocrit, hemoglobin, VEGF, NO, EGF, IL-1ra, and IL-10 increased in the ubiquinol group while IL-1, IL-8, and MCP-1 decreased. Ubiquinol supplementation during high intensity exercise could modulate inflammatory signaling, expression of pro-inflammatory, and increasing some anti-inflammatory cytokines. During exercise, RBC, hemoglobin, hematocrit, VEGF, and EGF increased in ubiquinol group, revealing a possible pro-angiogenic effect, improving oxygen supply and exerting a possible protective effect on other physiological alterations.

Low back pain and calf pain in a recreational runner masking peripheral artery disease: A case report

Background: Running is one of the most popular sports worldwide due to its low costs and its beneficial impact on health. Recent evidence suggests 11% to 85% of recreational runners experience at least one running-related injury each year and most of these are related to musculoskeletal conditions. The aim of this case report is to describe the clinical decision-making process that guided a physiotherapist to suspect a non-musculoskeletal cause in a recreational runner presenting with low back pain and calf pain secondary to Peripheral Artery Disease.Case Presentation: This case report describes the clinical history, clinical exam, laboratory and imaging tests, and surgical procedure of a 65 y.o. amateur runner suffering low back pain and left calf pain for 3 months. The patient's clinical findings suggested that referral to another health-care provider was required to explore potential non-musculoskeletal sources of pain. An angioplasty was necessary to solve the patient's clinical situation.Discussion and Conclusion: In this patient case, clinical findings along with a comprehensive family and personal history, ruled out a musculoskeletal condition and implicated a vascular condition.

Supervised walking exercise therapy improves gait biomechanics in patients with peripheral artery disease

OBJECTIVE

In patients with peripheral artery disease (PAD), supervised exercise therapy is a first line of treatment because it increases maximum walking distances comparable with surgical revascularization therapy. Little is known regarding gait biomechanics after supervised exercise therapy. This study characterized the effects of supervised exercise therapy on gait biomechanics and walking distances in claudicating patients with PAD.

METHODS

Forty-seven claudicating patients with PAD underwent gait analysis before and immediately after 6 months of supervised exercise therapy. Exercise sessions consisted of a 5-minute warmup of mild walking and stretching of upper and lower leg muscles, 50 minutes of intermittent treadmill walking, and 5 minutes of cooldown (similar to warmup) three times per week. Measurements included self-perceived ambulatory limitations measured by questionnaire, the ankle-brachial index (ABI), walking distance measures, maximal plantar flexor strength measured by isometric dynamometry, and overground gait biomechanics trials performed before and after the onset of claudication pain. Paired t-tests were used to test for differences in quality of life, walking distances, ABI, and maximal strength. A two-factor repeated measures analysis of variance determined differences for intervention and condition for gait biomechanics dependent variables.

RESULTS

After supervised exercise therapy, quality of life, walking distances, and maximal plantar flexor strength improved, although the ABI did not significantly change. Several gait biomechanics parameters improved after the intervention, including torque and power generation at the ankle and hip. Similar to previous studies, the onset of claudication pain led to a worsening gait or a gait that was less like healthy individuals with a pain-free gait.

CONCLUSIONS

Six months of supervised exercise therapy produced increases in walking distances and quality of life that are consistent with concurrent improvements in muscle strength and gait biomechanics. These improvements occurred even though the ABI did not improve. Future work should examine the benefits of supervised exercise therapy used in combination with other available treatments for PAD.

Development of an Exercise Training Protocol to Investigate Arteriogenesis in a Murine Model of Peripheral Artery Disease

Exercise is a treatment option in peripheral artery disease (PAD) patients to improve their clinical trajectory, at least in part induced by collateral growth. The ligation of the femoral artery (FAL) in mice is an established model to induce arteriogenesis. We intended to develop an animal model to stimulate collateral growth in mice through exercise. The training intensity assessment consisted of comparing two different training regimens in C57BL/6 mice, a treadmill implementing forced exercise and a free-to-access voluntary running wheel. The mice in the latter group covered a much greater distance than the former pre- and postoperatively. C57BL/6 mice and hypercholesterolemic ApoE-deficient (ApoE^−/−) mice were subjected to FAL and had either access to a running wheel or were kept in motion-restricting cages (control) and hind limb perfusion was measured pre- and postoperatively at various times. Perfusion recovery in C57BL/6 mice was similar between the groups. In contrast, ApoE^−/− mice showed significant differences between training and control 7 d postoperatively with a significant increase in pericollateral macrophages while the collateral diameter did not differ between training and control groups 21 d after surgery. ApoE^−/− mice with running wheel training is a suitable model to simulate exercise induced collateral growth in PAD. This experimental set-up may provide a model for investigating molecular training effects.

Placental growth factor levels in quadriceps muscle are reduced by a Western diet in association with advanced glycation end products

In peripheral artery disease (PAD), atherosclerotic occlusion chronically impairs limb blood flow. Arteriogenesis (collateral artery remodeling) is a vital adaptive response to PAD that protects tissue from ischemia. People with type II diabetes have a high risk of developing PAD and would benefit from arteriogenesis. However, arteriogenesis is suppressed in people with diabetes by a multifaceted mechanism which remains incompletely defined. Upregulation of placental growth factor (PLGF) is a key early step in arteriogenesis. Therefore, we hypothesized that metabolic dysfunction would impair PLGF expression in skeletal muscle. We tested this hypothesis in C57BL/6J and ApoE^-/- mice of both sexes fed a Western diet (WD) for 24 wk. We first assessed baseline levels of PLGF, vascular endothelial growth factor (VEGF-A), and VEGF receptor 1 (VEGFR1) protein in hindlimb skeletal muscle. Only PLGF was consistently decreased by the WD. We next investigated the effect of 24 wk of the WD on the response of PLGF, VEGF-A, VEGFR1, and monocyte chemoattractant protein-1 (MCP-1) to the physiological stimulus of vascular occlusion. Hindlimb ischemia was induced in mice by gradual femoral artery occlusion using an ameroid constrictor. Growth factor levels were measured 3-28 days postsurgery. In C57BL/6J mice, the WD decreased and delayed upregulation of PLGF and abolished upregulation of VEGF-A and VEGFR1 but had no effect on MCP-1. In ApoE^-/- mice fed either diet, all factors tested failed to respond to occlusion. Metabolic phenotyping of mice and in vitro studies suggest that an advanced glycation end product/TNFα-mediated mechanism could contribute to the effects observed in vivo.NEW & NOTEWORTHY In this study, we tested the effect of a Western diet on expression of the arteriogenic growth factor placental growth factor (PLGF) in mouse skeletal muscle. We provide the first demonstration that a Western diet interferes with both baseline expression and hindlimb ischemia-induced upregulation of PLGF. We further identify a potential role for advanced glycation end product/TNFα signaling as a negative regulator of PLGF. These studies provide insight into one possible mechanism by which type II diabetes may limit collateral growth.

Impacts of aquatic walking on arterial stiffness, exercise tolerance, and physical function in patients with peripheral artery disease: a randomized clinical trial

Peripheral artery disease (PAD) is an atherosclerotic disease that is associated with attenuated vascular function, cardiorespiratory capacity, physical function, and muscular strength. It is essential to combat these negative effects on health by incorporating lifestyle interventions to slow disease progression, such as exercise. We sought to examine the effects of aquatic walking exercise on cardiovascular function, cardiorespiratory capacity [maximal volume of oxygen consumption (V̇o_2max)], exercise tolerance [6-min walking distance (6MWD)], physical function, muscular strength, and body composition in patients with PAD. Patients with PAD (n = 72) were recruited and randomly assigned to a 12-wk aquatic walking training group (AQ, n = 35) or a control group (CON, n = 37). The AQ group performed walking and leg exercises in waist-to-chest-deep water. Leg arterial stiffness [femoral-to-ankle pulse wave velocity (legPWV)], heart rate (HR), blood pressure (BP), ankle-to-brachial index (ABI), V̇o_2max, 6MWD, physical function, muscular strength, body composition, resting metabolic rate (RMR), and flexibility were measured before and after 12 wk. There were significant group × time interactions (P < 0.05) after 12 wk for legPWV and HR, which significantly decreased (P < 0.05) in AQ, and V̇o_2max, 6MWD, physical function, and muscular strength, which significantly increased (P < 0.05) in AQ, compared with no changes in CON. There were no significant differences (P > 0.05) for BP, ABI, RMR, or flexibility after 12 wk. Interestingly, there was relatively high adherence (84%) to the aquatic walking exercise program in this population. These results suggest that aquatic walking exercise is an effective therapy to reduce arterial stiffness and resting HR and improve cardiorespiratory capacity, exercise tolerance, physical function, and muscular strength in patients with PAD.NEW & NOTEWORTHY The results of this study reveal for the first time that aquatic walking exercise can decrease arterial stiffness and improve exercise tolerance, cardiorespiratory capacity, and muscular strength in patients with peripheral artery disease (PAD). Aquatic walking exercise training demonstrates relatively high exercise adherence in this population. Aquatic walking exercise training may be a useful therapeutic intervention for improving physical function in patients with PAD.

A randomized, placebo-controlled trial of canakinumab in patients with peripheral artery disease

Extensive atherosclerotic plaque burden in the lower extremities often leads to symptomatic peripheral artery disease (PAD) including impaired walking performance and claudication. Interleukin-1β (IL-1β) may play an important pro-inflammatory role in the pathogenesis of this disease. Interruption of IL-1β signaling was hypothesized to decrease plaque progression in the leg macrovasculature and improve the mobility of patients with PAD with intermittent claudication. Thirty-eight patients (mean age 65 years; 71% male) with symptomatic PAD (confirmed by ankle-brachial index) were randomized 1:1 to receive canakinumab (150 mg subcutaneously) or placebo monthly for up to 12 months. The mean vessel wall area (by 3.0 T black-blood magnetic resonance imaging (MRI)) of the superficial femoral artery (SFA) was used to measure plaque volume. Mobility was assessed using the 6-minute walk test. Canakinumab was safe and well tolerated. Markers of systemic inflammation (interleukin-6 and high-sensitivity C-reactive protein) fell as early as 1 month after treatment. MRI (32 patients at 3 months; 21 patients at 12 months) showed no evidence of plaque progression in the SFA in either placebo-treated or canakinumab-treated patients. Although an exploratory endpoint, placebo-adjusted maximum and pain-free walking distance (58 m) improved as early as 3 months after treatment with canakinumab when compared with placebo. Although canakinumab did not alter plaque progression in the SFA, there is an early signal that it may improve maximum and pain-free walking distance in patients with symptomatic PAD. Larger studies aimed at this endpoint will be required to definitively demonstrate this. ClinicalTrials.gov Identifier: NCT01731990.

Ankle-brachial index, arterial stiffness, and biomarkers in the prediction of mortality and outcomes in patients with end-stage kidney disease

BACKGROUND

Although ankle-brachial index (ABI) and brachial-ankle pulse wave velocity (baPWV) are significant predictors of major adverse cardiovascular event (MACE), their prognostic value in association with biomarkers has not been fully evaluated in patients with end-stage kidney disease (ESKD).

HYPOTHESIS

We hypothesized that ABI/baPWV would provide better prognostic value independent of biomarkers in ESKD patients.

METHODS

This study included 104 ESKD patients treated with maintenance hemodialysis who underwent ABI and baPWV examinations and laboratory tests, including brain-natriuretic peptide, high-sensitive cardiac troponin T (hs-cTnT), and high-sensitive C-reactive protein (hs-CRP). MACE was defined as a composite event of all-cause death, acute coronary syndrome, and stroke.

RESULTS

During a mean follow-up of 3.6 ± 1.7 years, a total of 51 MACE were observed. The independent factors associated with MACE were age >75 years (adjusted hazard ratio [HR], 2.15; P < .05), abnormal ABI (adjusted HR, 2.01; P < .05), left ventricular ejection fraction (LVEF) <50% (adjusted HR, 3.33; P < .001), the upper tertile of hs-cTnT (adjusted HR, 2.77; P < .05), and hs-CRP (HR, 1.96; P < .05). However, baPWV did not remain as an independent predictor of MACE in the entire cohort and also in patients without abnormal ABI. The combination of predictors improves the predictive value of MACE, providing increased HR with 4.00 for abnormal ABI + hs-CRP, 4.42 for abnormal ABI + hs-cTnT, and 7.04 for abnormal ABI + LVEF <50% (all P < .001).

CONCLUSION

Abnormal ABI is a robust predictor of MACE independent of biomarkers and their combination provides better risk stratification compared with a single predictor in ESKD patients.

Substance P accelerates wound repair by promoting neovascularization and preventing inflammation in an ischemia mouse model

AIMS

Arterial insufficiency ulcers are frequent complications of peripheral artery disease and infection or long-term neglect of the ulcer can eventually lead to amputation of the affected body part. An ischemic environment, caused by interrupted blood flow, affects the supply of nutrients and elongates the inflammation period, inducing tissue degeneration. Thus, the modulation of neovascularization and inflammation could be an ideal therapeutic strategy for ischemic wound healing. This study aimed to elucidate whether systemically administered substance P (SP) could promote ischemic wound repair in mice by restoring blood perfusion and suppressing inflammation.

MAIN METHODS

The effects of SP were assessed by analyzing wound size, blood flow, epidermal and dermal layer regeneration, vessel formation, and the inflammatory cytokine profiles in a hind-limb ischemia non-clinical mouse model.

KEY FINDINGS

SP-treated mice exhibited dramatically rapid wound healing and restoration of blood flow within the ischemic zone, compared with saline-treated mice. Notably, SP-treated mice showed enhanced pericyte-covered vasculature compared to saline-treated mice. Moreover, anti-inflammatory effects were detected in mice in the SP-treated group, including suppression of inflammation-mediated spleen enlargement, reduction of tumor necrosis factor-alpha, and promotion of circulatory interleukin-10 levels.

SIGNIFICANCE

These results suggest that SP could be a possible therapeutic candidate for patients with peripheral artery disease, including those with ischemic ulcers.

Metabolic regulation of exercise-induced angiogenesis

Skeletal muscle relies on an ingenious network of blood vessels, which ensures optimal oxygen and nutrient supply. An increase in muscle vascularization is an early adaptive event to exercise training, but the cellular and molecular mechanisms underlying exercise-induced blood vessel formation are not completely clear. In this review, we provide a concise overview on how exercise-induced alterations in muscle metabolism can evoke metabolic changes in endothelial cells (ECs) that drive muscle angiogenesis. In skeletal muscle, angiogenesis can occur via sprouting and splitting angiogenesis and is dependent on vascular endothelial growth factor (VEGF) signaling. In the resting muscle, VEGF levels are controlled by the estrogen-related receptor γ (ERRγ). Upon exercise, the transcriptional coactivator peroxisome-proliferator-activated receptor-γ coactivator-1α (PGC1α) orchestrates several adaptations to endurance exercise within muscle fibers and simultaneously promotes transcriptional activation of Vegf expression and increased muscle capillary density. While ECs are highly glycolytic and change their metabolism during sprouting angiogenesis in development and disease, a similar role for EC metabolism in exercise-induced angiogenesis in skeletal muscle remains to be elucidated. Nonetheless, recent studies have illustrated the importance of endothelial hydrogen sulfide and sirtuin 1 (SIRT1) activity for exercise-induced angiogenesis, suggesting that EC metabolic reprogramming may be fundamental in this process. We hypothesize that the exercise-induced angiogenic response can also be modulated by metabolic crosstalk between muscle and the endothelium. Defining the underlying molecular mechanisms responsible for skeletal muscle angiogenesis in response to exercise will yield valuable insight into metabolic regulation as well as the determinants of exercise performance.

A systematic comparison of exercise training protocols on animal models of cardiovascular capacity

Cardiovascular disease (CVD) is a major global cause of mortality, which has prompted numerous studies seeking to reduce the risk of heart failure and sudden cardiac death. While regular physical activity is known to improve CVD associated morbidity and mortality, the optimal duration, frequency, and intensity of exercise remains unclear. To address this uncertainty, various animal models have been used to study the cardioprotective effects of exercise and related molecular mechanism such as the mice training models significantly decrease size of myocardial infarct by affecting Kir6.1, VSMC sarc-K_ATP channels, and pulmonary eNOS. Although these findings cement the importance of animal models in studying exercise induced cardioprotection, the vast assortment of exercise protocols makes comparison across studies difficult. To address this issue, we review and break down the existent exercise models into categories based on exercise modality, intensity, frequency, and duration. The timing of sample collection is also compared and sorted into four distinct phases: pre-exercise (Phase I), mid-exercise (Phase II), exercise recovery (Phase III), and post-exercise (Phase IV). Finally, because the life-span of animals so are limited, small changes in animal exercise duration can corresponded to untenable amounts of human exercise. To address this limitation, we introduce the Life-Span Relative Exercise Time (RET_{life span}) as a method of accurately defining short-term, medium-term and long-term exercise relative to the animal's life expectancy. Systematic organization of existent protocols and this new system of defining exercise duration will allow for a more solid framework from which researchers can extrapolate animal model data to clinical application.

Attenuation of oxidative stress-induced lesions in skeletal muscle in a mouse model of obesity-independent hyperlipidaemia and atherosclerosis through the inhibition of Nox2 activity

Obesity leading to hyperlipidaemia and atherosclerosis is recognised to induce morphological and metabolic changes in many tissues. However, hyperlipidaemia can occur in the absence of obesity. The impact of the latter scenario on skeletal muscle and liver is not understood sufficiently. In this regard, we used the Apolipoprotein E-deficient (ApoE^-/-) mouse model, an established model of hyperlipidaemia and atherosclerosis, that does not become obese when subjected to a high-fat diet, to determine the impact of Western-type diet (WD) and ApoE deficiency on skeletal muscle morphological, metabolic and biochemical properties. To establish the potential of therapeutic targets, we further examined the impact of Nox2 pharmacological inhibition on skeletal muscle redox biology. We found ectopic lipid accumulation in skeletal muscle and the liver, and altered skeletal muscle morphology and intramuscular triacylglycerol fatty acid composition. WD and ApoE deficiency had a detrimental impact in muscle metabolome, followed by perturbed gene expression for fatty acid uptake and oxidation. Importantly, there was enhanced oxidative stress in the skeletal muscle and development of liver steatosis, inflammation and oxidative protein modifications. Pharmacological inhibition of Nox2 decreased reactive oxygen species production and protein oxidative modifications in the muscle of ApoE^-/- mice subjected to a Western-type diet. This study provides key evidence to better understand the pathophysiology of skeletal muscle in the context of hyperlipidaemia and atherosclerosis and identifies Nox2 as a potential target for attenuating oxidative stress in skeletal muscle in a mouse model of obesity-independent hyperlipidaemia.

Near infrared spectroscopy-guided exercise training for claudication in peripheral arterial disease

Rationale

Supervised treadmill exercise for claudication in peripheral arterial disease is effective but poorly tolerated because of ischemic leg pain. Near infrared spectroscopy allows non-invasive detection of muscle ischemia during exercise, allowing for characterization of tissue perfusion and oxygen utilization during training.

Objective

We evaluated walking time, muscle blood flow, and muscle mitochondrial capacity in patients with peripheral artery disease after a traditional pain-based walking program and after a muscle oxygen-guided walking program.

Method and results

Patients with peripheral artery disease trained thrice weekly in 40-minute-long sessions for 12 weeks, randomized to oxygen-guided training ( n = 8, age 72 ± 9.7 years, 25% female) versus traditional pain-based training ( n = 10, age 71.6 ± 8.8 years, 20% female). Oxygen-guided training intensity was determined by maintaining a 15% reduction in skeletal muscle oxygenation by near infrared spectroscopy rather than relying on symptoms of pain to determine exercise effort. Pain free and maximal walking times were measured with a 12-minute Gardner treadmill test. Gastrocnemius mitochondrial capacity and blood flow were measured using near infrared spectroscopy. Baseline pain-free walking time was similar on a Gardner treadmill test (2.5 ± 0.9 vs. 3.6 ± 1.0 min, p = 0.5). After training, oxygen-guided cohorts improved similar to pain-guided cohorts (pain-free walking time 6.7 ± 0.9 vs. 6.9 ± 1.1 min, p < 0.01 for change from baseline and p = 0.97 between cohorts). Mitochondrial capacity improved in both groups but more so in the pain-guided cohort than in the oxygen-guided cohort (38.8 ± 8.3 vs. 14.0 ± 9.3, p = 0.018). Resting muscle blood flow did not improve significantly in either group with training.

Conclusions

Oxygen-guided exercise training improves claudication comparable to pain-based training regimens. Adaptations in mitochondrial function rather than increases in limb perfusion may account for functional improvement. Increases in mitochondrial oxidative capacity may be proportional to the degree of tissue hypoxia during exercise.

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

Background

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

Method

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

Results

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

Conclusion

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

Increased skeletal muscle mitochondrial free radical production in peripheral arterial disease despite preserved mitochondrial respiratory capacity

NEW FINDINGS

What is the central question of this study? What is the degree to which skeletal muscle mitochondria-derived reactive oxygen species (ROS) production is linked to impaired skeletal muscle function in patients with early-stage peripheral arterial disease (PAD) and what is the impact on mitochondrial respiratory capacity? What is the main finding and its importance? This is the first study to document increased mitochondria-derived reactive oxygen species production associated with elevated intramuscular oxidative stress, despite preserved mitochondrial respiratory function, in patients with PAD. Furthermore, systemic inflammation, mitochondria-derived ROS production and skeletal muscle oxidative stress were strongly correlated to disease severity, as indicated by ankle-brachial index, in patients with PAD.

ABSTRACT

Skeletal muscle mitochondrial dysfunction, which is not fully explained by disease-related arterial occlusion, has been implicated in the pathophysiology of peripheral arterial disease (PAD). Therefore, this study comprehensively assessed mitochondrial respiratory function in biopsies from the gastrocnemius of 10 patients with PAD (Fontaine Stage II) and 12 healthy controls (HC). Intramuscular and systemic inflammation, mitochondria-derived reactive oxygen species (ROS) production, and oxidative stress were also assessed to better understand the mechanisms responsible for the proposed PAD-induced mitochondrial dysfunction. Interestingly, mitochondrial respiratory capacity, assessed as complex I (CI) and complex II (CII)-driven State 3 respiration, measured separately and in combination (State 3 CI+II), revealed no difference between the patients with PAD and the HC. However, mitochondria-derived ROS production was significantly elevated in PAD (HC: 1.0 ± 0.9; PAD: 4.3 ± 1.0 AU (mg tissue)^-1 ). Furthermore, patients with PAD exhibited significantly greater concentrations of the pro-inflammatory markers tumour necrosis factor α in plasma (HC: 0.9 ± 0.4; PAD: 2.0 ± 0.3 pg ml^-1 ) and interleukin 6 in both plasma (HC: 2.3 ± 0.4; PAD: 4.3 ± 0.5 pg ml^-1 ) and muscle (∼75% greater). Intramuscular oxidative stress, assessed by protein carbonyls and 4-hydroxynonenal, was significantly greater in PAD compared to HC. Ankle brachial index was significantly correlated with intramuscular inflammation, oxidative stress and mitochondria-derived ROS production. Thus, elevated intramuscular inflammation, oxidative stress and mitochondria-derived ROS production are likely to contribute to the pathophysiology of the skeletal muscle dysfunction associated with PAD, even in the presence of preserved mitochondrial respiratory function in this population.

Eight weeks of nitrate supplementation improves blood flow and reduces the exaggerated pressor response during forearm exercise in peripheral artery disease

Peripheral artery disease (PAD) is characterized by a reduced blood flow (BF) and an elevated blood pressure (pressor) response during lower extremity exercise. Although PAD is evident in the upper extremities, no studies have determined BF and pressor responses during upper extremity exercise in PAD. Emerging evidence suggests that inorganic nitrate supplementation may serve as an alternative dietary strategy to boost nitric oxide bioavailability, improving exercising BF and pressor responses during exercise. The present study investigated 1) BF and pressor responses to forearm exercise in patients with PAD ( n = 21) relative to healthy age-matched control subjects ( n = 16) and 2) whether 8 wk of NaNO₃ supplementation influenced BF and pressor responses to forearm exercise in patients with PAD. Patients with moderate to severe PAD were randomly assigned to a NaNO₃ (1 g/day, n = 13)-treated group or a placebo (microcrystalline cellulose, n = 8)-treated group. Brachial artery forearm BF (FBF; via Doppler) and blood pressure (via finger plethysmography) were measured during mild-intensity (~3.5-kg) and moderate-intensity (~7-kg) handgrip exercise. The absolute change (from baseline) in FBF was reduced (except in the 3.5-kg condition) and BP responses were increased in patients with PAD compared with healthy control subjects in 3.5- and 7-kg conditions (all P < 0.05). Plasma nitrate and nitrite were elevated, exercising (7-kg) ΔFBF was improved (from 141 ± 17 to 172 ± 20 ml/min), and mean arterial pressure response was reduced (from 13 ± 1 to 9 ± 1 mmHg, P < 0.05) in patients with PAD that received NaNO₃ supplementation for 8 wk relative to those that received placebo. These results suggest that the BF limitation and exaggerated pressor response to moderate-intensity forearm exercise in patients with PAD are improved with 8 wk of NaNO₃ supplementation. NEW & NOTEWORTHY Peripheral artery disease (PAD) results in an exaggerated pressor response and reduced blood flow during lower limb exercise; however, the effect of PAD in the upper limbs has remained unknown. These results suggest that 8 wk of inorganic nitrate supplementation improves the blood flow limitation and exaggerated pressor response to moderate-intensity forearm exercise in PAD.

Exercise for intermittent claudication

BACKGROUND

Exercise programmes are a relatively inexpensive, low-risk option compared with other, more invasive therapies for treatment of leg pain on walking (intermittent claudication (IC)). This is the fourth update of a review first published in 1998.

OBJECTIVES

Our goal was to determine whether an exercise programme was effective in alleviating symptoms and increasing walking treadmill distances and walking times in people with intermittent claudication. Secondary objectives were to determine whether exercise was effective in preventing deterioration of underlying disease, reducing cardiovascular events, and improving quality of life.

SEARCH METHODS

For this update, the Cochrane Vascular Information Specialist searched the Specialised Register (last searched 15 November 2016) and the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 10) via the Cochrane Register of Studies Online, along with trials registries.

SELECTION CRITERIA

Randomised controlled trials of an exercise regimen versus control or versus medical therapy for people with IC due to peripheral arterial disease (PAD). We included any exercise programme or regimen used for treatment of IC, such as walking, skipping, and running. Inclusion of trials was not affected by duration, frequency, or intensity of the exercise programme. Outcome measures collected included treadmill walking distance (time to onset of pain or pain-free walking distance and maximum walking time or maximum walking distance), ankle brachial index (ABI), quality of life, morbidity, or amputation; if none of these was reported, we did not include the trial in this review.

DATA COLLECTION AND ANALYSIS

For this update (2017), RAL and AH selected trials and extracted data independently. We assessed study quality by using the Cochrane 'Risk of bias' tool. We analysed continuous data by determining mean differences (MDs) and 95% confidence intervals (CIs), and dichotomous data by determining risk ratios (RRs) and 95% CIs. We pooled data using a fixed-effect model unless we identified significant heterogeneity, in which case we used a random-effects model. We used the GRADE approach to assess the overall quality of evidence supporting the outcomes assessed in this review.

MAIN RESULTS

We included two new studies in this update and identified additional publications for previously included studies, bringing the total number of studies meeting the inclusion criteria to 32, and involving a total of 1835 participants with stable leg pain. The follow-up period ranged from two weeks to two years. Types of exercise varied from strength training to polestriding and upper or lower limb exercises; supervised sessions were generally held at least twice a week. Most trials used a treadmill walking test for one of the primary outcome measures. The methodological quality of included trials was moderate, mainly owing to absence of relevant information. Most trials were small and included 20 to 49 participants. Twenty-seven trials compared exercise versus usual care or placebo, and the five remaining trials compared exercise versus medication (pentoxifylline, iloprost, antiplatelet agents, and vitamin E) or pneumatic calf compression; we generally excluded people with various medical conditions or other pre-existing limitations to their exercise capacity.Meta-analysis from nine studies with 391 participants showed overall improvement in pain-free walking distance in the exercise group compared with the no exercise group (MD 82.11 m, 95% CI 71.73 to 92.48, P < 0.00001, high-quality evidence). Data also showed benefit from exercise in improved maximum walking distance (MD 120.36 m, 95% CI 50.79 to 189.92, P < 0.0007, high-quality evidence), as revealed by pooling data from 10 studies with 500 participants. Improvements were seen for up to two years.Exercise did not improve the ABI (MD 0.04, 95% CI 0.00 to 0.08, 13 trials, 570 participants, moderate-quality evidence). Limited data were available for the outcomes of mortality and amputation; trials provided no evidence of an effect of exercise, when compared with placebo or usual care, on mortality (RR 0.92, 95% CI 0.39 to 2.17, 5 trials, 540 participants, moderate-quality evidence) or amputation (RR 0.20, 95% CI 0.01 to 4.15, 1 trial, 177 participants, low-quality evidence).Researchers measured quality of life using Short Form (SF)-36 at three and six months. At three months, the domains 'physical function', 'vitality', and 'role physical' improved with exercise; however this was a limited finding, as it was reported by only two trials. At six months, meta-analysis showed improvement in 'physical summary score' (MD 2.15, 95% CI 1.26 to 3.04, P = 0.02, 5 trials, 429 participants, moderate-quality evidence) and in 'mental summary score' (MD 3.76, 95% CI 2.70 to 4.82, P < 0.01, 4 trials, 343 participants, moderate-quality evidence) secondary to exercise. Two trials reported the remaining domains of the SF-36. Data showed improvements secondary to exercise in 'physical function' and 'general health'. The other domains - 'role physical', 'bodily pain', 'vitality', 'social', 'role emotional', and 'mental health' - did not show improvement at six months.Evidence was generally limited in trials comparing exercise versus antiplatelet therapy, pentoxifylline, iloprost, vitamin E, and pneumatic foot and calf compression owing to small numbers of trials and participants.Review authors used GRADE to assess the evidence presented in this review and determined that quality was moderate to high. Although results showed significant heterogeneity between trials, populations and outcomes were comparable overall, with findings relevant to the claudicant population. Results were pooled for large sample sizes - over 300 participants for most outcomes - using reproducible methods.

AUTHORS' CONCLUSIONS

High-quality evidence shows that exercise programmes provided important benefit compared with placebo or usual care in improving both pain-free and maximum walking distance in people with leg pain from IC who were considered to be fit for exercise intervention. Exercise did not improve ABI, and we found no evidence of an effect of exercise on amputation or mortality. Exercise may improve quality of life when compared with placebo or usual care. As time has progressed, the trials undertaken have begun to include exercise versus exercise or other modalities; therefore we can include fewer of the new trials in this update.