Exercise and intermittent claudication. Blood flow in the calf muscle during walking studied by the xenon-133 clearance method

Neuromuscular stimulation ameliorates ischemia-induced walking impairment in the rat claudication model

Intermittent claudication (IC) is the most common symptom of peripheral arterial disease which significantly deteriorates the quality of life of patients. Exercise training is by far the most effective treatment for IC; however, the underlying mechanisms remain elusive. To determine the local mechanisms by which exercise training improves walking performance in claudicants, we developed an implantable device to locally induce ischemic skeletal muscle contraction mimicking exercise via electrical stimulation (ES). Rats were assigned to four groups, Sham, Ischemia (Isch), Isch + exercise and Isch + ES groups. Following both unilateral femoral and iliac artery occlusion, rats showed sustained impairment of walking performance in the treadmill test. Chronic low-frequency ES of ischemic skeletal muscles for 2 weeks significantly recovered the occlusion-induced walking impairment in the rat claudication model. We further analyzed the ischemic skeletal muscles immunohistochemically following ES or exercise training; both ES and exercise training significantly increased capillaries in the ischemic skeletal muscles and shifted the muscle fibers toward oxidative types. These findings demonstrate that ES takes on common features of exercise in the rat claudication model, which may facilitate investigations on the local mechanisms of exercise-induced functional recovery.

Dynamic magnetic resonance measurements of calf muscle oxygenation and energy metabolism in peripheral artery disease

Background

Clinical assessments of peripheral artery disease (PAD) severity are insensitive to pathophysiological changes in muscle tissue oxygenation and energy metabolism distal to the affected artery.

Purpose

To quantify the blood oxygenation level‐dependent (BOLD) response and phosphocreatine (PCr) recovery kinetics on a clinical MR system during a single exercise‐recovery session in PAD patients.

Study Type

Case–control study.

Subjects

Fifteen Fontaine stage II patients, and 18 healthy control subjects

Field Strength/Sequence

Interleaved dynamic multiecho gradient‐echo ¹H T₂* mapping and adiabatic pulse‐acquire ³¹P‐MR spectroscopy at 3T.

Assessment

Blood pressure in the arms and ankles were measured to determine the ankle‐brachial index (ABI). Subjects performed a plantar flexion exercise‐recovery protocol. The gastrocnemius and soleus muscle BOLD responses were characterized using the T₂* maps. High‐energy phosphate metabolite concentrations were quantified by fitting the series of ³¹P‐MR spectra. The PCr recovery time constant (τ_PCr) was derived as a measure of in vivo mitochondrial oxidative capacity.

Statistical Tests

Comparisons between groups were performed using two‐sided Mann–Whitney U‐tests. Relations between variables were assessed by Pearson's r correlation coefficients.

Results

The amplitude of the functional hyperemic BOLD response in the gastrocnemius muscle was higher in PAD patients compared with healthy subjects (–3.8 ± 1.4% vs. –1.4 ± 0.3%; P < 0.001), and correlated with the ABI (r = 0.79; P < 0.001). PCr recovery was slower in PAD patients (τ_PCr = 52.0 ± 13.5 vs. 30.3 ± 9.7 sec; P < 0.0001), and correlated with the ABI (r = –0.64; P < 0.001). Moreover, τ_PCr correlated with the hyperemic BOLD response in the gastrocnemius muscle (r = –0.66; P < 0.01).

Data Conclusion

MR readouts of calf muscle tissue oxygenation and high‐energy phosphate metabolism were acquired essentially simultaneously during a single exercise‐recovery session. A pronounced hypoxia‐triggered vasodilation in PAD is associated with a reduced mitochondrial oxidative capacity.

Level of Evidence: 2

Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2020;51:98–107.

Heat therapy vs. supervised exercise therapy for peripheral arterial disease: a 12-wk randomized, controlled trial

Peripheral arterial disease (PAD) is characterized by lower limb atherosclerosis impairing blood supply and causing walking-induced leg pain or claudication. Adherence to traditional exercise training programs is poor due to these symptoms despite exercise being a mainstay of conservative treatment. Heat therapy improves many cardiovascular health outcomes, so this study tested if this was a viable alternative cardiovascular therapy for PAD patients. Volunteers with PAD were randomized to 12 wk of heat ( n = 11; mean age 76 ± 8 yr, BMI 28.7 ± 3.5 kg/m2, 4 females) or exercise ( n = 11; 74 ± 10 yr, 28.5 ± 6.8 kg/m2, 3 females). Heat involved spa bathing at ∼39°C, 3–5 days/wk for ≤30 min, followed by ≤30 min of callisthenics. Exercise involved ≤90 min of supervised walking and gym-based exercise, 1–2 days/wk. Following the interventions, total walking distance during a 6-min walk test increased (from ∼350 m) by 41 m (95% CI: [13, 69], P = 0.006) regardless of group, and pain-free walking distance increased (from ∼170 m) by 43 m ([22, 63], P < 0.001). Systolic blood pressure was reduced more following heat (−7 mmHg, [−4, −10], P < 0.001) than following exercise (−3 mmHg, [0, −6], P = 0.078), and diastolic and mean arterial pressure decreased by 4 mmHg in both groups ( P = 0.002). There were no significant changes in blood volume, ankle-brachial index, or measures of vascular health. There were no differences in the improvement in functional or blood pressure outcomes between heat and exercise in individuals with PAD.

NEW & NOTEWORTHY Heat therapy via hot-water immersion and supervised exercise both improved walking distance and resting blood pressure in peripheral arterial disease (PAD) patients over 12 wk. Adherence to heat therapy was excellent, and the heat intervention was well tolerated. The results of the current study indicate that heat therapy can improve functional ability and has potential as an effective cardiovascular conditioning tool for individuals with PAD.

Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/heat-therapy-vs-exercise-in-peripheral-arterial-disease/ .

Comparison of leg loader and treadmill exercise for evaluating patients with peripheral artery disease

The exercise ankle-brachial index (ABI) helps diagnose lower extremity peripheral artery disease (PAD). Patients with comorbidities may be unable to perform treadmill exercise, the most common stress loading test. While the active pedal plantar flexion (APP) test using the leg loader, simple and easy stress loading device, could be an alternative, there are no data comparing the leg loader and treadmill exercise. Therefore, we aimed to compare APP using the leg loader and treadmill exercise to evaluate PAD. A total of 27 patients (54 limbs) diagnosed with PAD with intermittent claudication and considered for angiography and/or endovascular treatment were recruited prospectively, and both the leg loader and treadmill were performed. There was a strong correlation (r = 0.925, p < 0.001) between the leg loader ABI and treadmill ABI; however, the decrease rate of the leg loader ABI was significantly less than that of treadmill ABI (14.0% [5.6, 30.1] vs. 25.8% [6.1, 53.1], p < 0.001). The number of patients who terminated the exercise prematurely due to dyspnea was four during the treadmill and zero during the leg loader. There was a good correlation between the leg loader ABI and treadmill ABI. Although leg loader, a simple, safe, and easy method, could be an alternative to diagnose PAD, further studies are needed to evaluate the diagnostic value of the leg loader in patients with borderline ABI or those unable to perform the treadmill.

Medical Management of Intermittent Claudication

The symptoms of intermittent claudication (IC) lead sufferers to seek medical attention, potentially leading to substantial workup and invasive testing. However, only a minority of people with IC develop limb-threatening ischemia or symptoms of significant lifestyle-limiting claudication. Patients with IC have a substantial risk of concomitant cardiovascular and cerebrovascular disease. Assessment of co-morbidities and control of risk factors reduce the cardiovascular risk of these patients. A multitude of drugs have been developed and tested in numerous trials for the symptoms of IC. Although no drug alone offers a “cure” to IC, some are used as adjuvant therapy to reduce claudication symptoms.

Exercise training and peripheral arterial disease

Peripheral arterial disease (PAD) is a common vascular disease that reduces blood flow capacity to the legs of patients. PAD leads to exercise intolerance that can progress in severity to greatly limit mobility, and in advanced cases leads to frank ischemia with pain at rest. It is estimated that 12 to 15 million people in the United States are diagnosed with PAD, with a much larger population that is undiagnosed. The presence of PAD predicts a 50% to 1500% increase in morbidity and mortality, depending on severity. Treatment of patients with PAD is limited to modification of cardiovascular disease risk factors, pharmacological intervention, surgery, and exercise therapy. Extended exercise programs that involve walking approximately five times per week, at a significant intensity that requires frequent rest periods, are most significant. Preclinical studies and virtually all clinical trials demonstrate the benefits of exercise therapy, including improved walking tolerance, modified inflammatory/hemostatic markers, enhanced vasoresponsiveness, adaptations within the limb (angiogenesis, arteriogenesis, and mitochondrial synthesis) that enhance oxygen delivery and metabolic responses, potentially delayed progression of the disease, enhanced quality of life indices, and extended longevity. A synthesis is provided as to how these adaptations can develop in the context of our current state of knowledge and events known to be orchestrated by exercise. The benefits are so compelling that exercise prescription should be an essential option presented to patients with PAD in the absence of contraindications. Obviously, selecting for a lifestyle pattern that includes enhanced physical activity prior to the advance of PAD limitations is the most desirable and beneficial.

Exercise interventions for patients with peripheral arterial disease: a review of the literature

Peripheral arterial disease (PAD) is a common chronic cardiovascular condition that affects the lower extremities and can substantially limit daily activities and quality of life. Lifestyle interventions, including smoking cessation, diet modification, regular physical activity, and pharmacotherapy, are often prescribed to treat patients with PAD. Exercise interventions can be effective in increasing claudication onset time and maximal walking distance. Of the various types of exercise interventions available for patients with PAD, little is known about the differences that may exist between men and women in patient response to such interventions. The purpose of this literature review is to examine the current knowledge of exercise interventions for individuals with mild (Fontaine stages I-II) PAD and to consider any differences that may exist between men and women. Women with PAD present with a different clinical profile compared with men, but respond similarly to an acute bout of exercise and a training program. Patients with PAD should be encouraged to walk regularly; however, more research is needed to determine differences between men and women in their response to various exercise interventions.

Potential clinical utility of partial body weight support on treadmill walking time in persons with intermittent claudication: a single case report

Intermittent claudication can seriously limit an individual's walking capacity. Walking programs are known to improve this limitation but could be limited by a person's ability to carry his or her own full body weight to perform the walking. We theorized that decreasing body weight, through mechanical unloading, might allow longer pain-free walking, thus potentially accelerating exercise training. This case report describes the effect of partial body weight support (PBWS) on walking time in a patient with claudication. A 60-year-old male with calf pain that prevented him from walking long distances or walking quickly was studied. The patient completed three treadmill walking tests (0%, 25%, and 50% PBWS) until claudication pain stopped him or 15 minutes elapsed. The participant walked 4:31 minutes at 0% PBWS with a pain rating of 3/4. He walked the full 15 minutes under each support condition with the same or less claudication pain (3/4 for 25% PBWS, 2/4 for 50% PBWS). This case reports the successful use of PBWS treadmill training for increasing walking time in an individual with intermittent claudication. If this finding holds true for a larger sample, PBWS may be a way for these individuals to participate in exercise training programs with less pain.

Effect of physical training on different categories of patients with intermittent claudication

The effect of supervised training was studied in 68 patients with intermittent claudication. Maximal walking distance was measured on a treadmill. Eight of the patients had resting pain in the leg when recumbent (group A), 25 had an initial walking distance of less than 500 m (group B), 11 had an initial walking distance of 500--1 000 m (group C), 24 had coronary insufficiency (group D). The study shows that training should be undertaken for at least three months. In some patients with resting pain, training led to relief of pain and surgical treatment was not necessary. Almost all patients without signs of coronary insufficiency increased their walking distance, compared to only 14 of the 24 patients with coronary insufficiency. Walking distance increased significantly in groups B and C and no significant difference was found between patients and proximal or distal arterial stenosis.

Alpha-adrenergic and neuropeptide Y Y1 receptor control of collateral circuit conductance: influence of exercise training

This study evaluated the role of alpha-adrenergic receptor- and neuropeptide Y (NPY) Y1 receptor-mediated vasoconstriction in the collateral circuit of the hind limb. Animals were evaluated either the same day (Acute) or 3 weeks following occlusion of the femoral artery; the 3-week animals were in turn limited to cage activity (Sed) or given daily exercise (Trained). Collateral-dependent blood flows (BFs) were measured during exercise with microspheres before and after alpha-receptor inhibition (phentolamine) and then NPY Y1 receptor inhibition (BIBP 3226) at the same running speed. Blood pressures (BPs) were measured above (caudal artery) and below (distal femoral artery) the collateral circuit. Arterial BPs were reduced by alpha-inhibition (50-60 mmHg) to approximately 75 mmHg, but not further by NPY Y1 receptor inhibition. Effective experimental sympatholysis was verified by 50-100% increases (P < 0.001) in conductance of active muscles not affected by femoral occlusion with receptor inhibition. In the absence of receptor inhibition, vascular conductance of the collateral circuit was minimal in the Acute group (0.13 +/- 0.02), increased over time in the Sed group (0.41 +/- 0.03; P < 0.001), and increased further in the Trained group (0.53 +/- 0.03; P < 0.02). Combined receptor inhibition increased collateral circuit conductances (P < 0.005), most in the Acute group (116 +/- 37%; P < 0.02), as compared to the Sed (41 +/- 6.6%; P < 0.001) and Trained (31 +/- 5.6%; P < 0.001) groups. Thus, while the sympathetic influence of the collateral circuit remained in the Sed and Trained animals, it became less influential with time post-occlusion. Collateral conductances were collectively greater (P < 0.01) in the Trained as compared to Sed group, irrespective of the presence or absence of receptor inhibition. Conductances of the active ischaemic calf muscle, with combined receptor inhibition, were suboptimal in the Acute group, but increased in Sed and Trained animals to exceptionally high values (e.g. red fibre section of the gastrocnemius: approximately 7 ml min(-1) (100 g)(-1) mmHg(-1)). Thus, occlusion of the femoral artery promulgated vascular adaptations, even in vessels that are not part of the collateral circuit. The presence of active sympathetic control of the collateral circuit, even with exercise training, raises the potential for reductions in collateral BF below that possible by the structure of the collateral circuit. However, even with release of this sympathetic vasoconstriction, conductance of the collateral circuit was significantly greater with exercise training, probably due to the network of structurally larger collateral vessels.

Estudo comparativo da evolução e sobrevida de pacientes com claudicação intermitente, com ou sem limitação para exercícios, acompanhados em ambulatório específico

CONTEXTO: Os fatores de risco para doença aterosclerótica, que influenciam na evolução natural dessa doença, estão bem estabelecidos, assim como o benefício do programa de exercícios para pacientes claudicantes. Entretanto, faltam informações sobre a relação entres limitações clínicas e fatores de risco, com desempenho do programa de caminhadas e suas implicações na evolução e mortalidade destes pacientes. OBJETIVO: Comparar, ao longo do tempo, a distância de claudicação e sobrevida de pacientes claudicantes em ambulatório específico, com ou sem limitação para exercícios. MÉTODOS: Foi feito um estudo tipo coorte retrospectivo de 185 pacientes e 469 retornos correspondentes, no período de 1999 a 2005, avaliando-se dados demográficos, distância média de claudicação (CI) e óbito. Os dados foram analisados nos programas Epi Info, versão 3.2, e SAS, versão 8.2. RESULTADOS: A idade média foi de 60,9±11,1 anos, sendo 61,1% do sexo masculino e 38,9% do sexo feminino. Oitenta e sete por cento eram brancos, e 13%, não-brancos. Os fatores de risco associados foram: hipertensão (69,7%), tabagismo (44,3%), dislipidemia (32,4%) e diabetes (28,6%). Nos claudicantes para menos de 500 m, a CI inicial em esteira foi de 154,0±107,6 m, e a CI final, de 199,8±120,5 m. Cerca de 45% dos pacientes tinham alguma limitação clínica para realizar o programa de exercícios preconizado, como: angina (26,0%), acidente vascular cerebral (4,3%), artropatia (3,8%), amputação menor ou maior com prótese (2,1%) ou doença pulmonar obstrutiva crônica (1,6%). Cerca de 11,4% dos pacientes tinham infarto do miocárdio prévio, e 5,4% deles usavam cardiotônico. O tempo de seguimento médio foi de 16,0±14,4 meses. A distância média de CI referida pelos pacientes aumentou 100% (de 418,47 m para 817,74 m) ao longo de 2 anos, nos grupos não-limitante (p < 0,001) e não-tabagista (p < 0,001). A sobrevida dos claudicantes foi significativamente menor no grupo com limitação. A análise de regressão logística mostrou que a limitação para realização de exercícios, isoladamente, influenciou significativamente na mortalidade (p < 0,001). CONCLUSÃO: A realização correta e regular dos exercícios e o abandono do fumo melhoram a distância de claudicação, além de reduzir a mortalidade nesses casos, seja por meio de efeitos positivos próprios do exercício, seja por meio de controle dos fatores de risco e de seus efeitos adversos.

Exercise training for claudication

Exercise advice is a well established component of the conservative management of intermittent claudication. Supervised programmes of exercise remain relatively uncommon and are provided mainly in secondary care. This review outlines the evidence for the effectiveness of different exercise regimens and the relative benefits of exercise therapy, where comparisons have been made with medical therapy, angioplasty and surgery.

Established and evolving medical therapies for claudication in patients with peripheral arterial disease

Claudication resulting from peripheral arterial disease causes substantial impairment in the ability to carry out normal daily activities. The medical treatments for claudication that are currently available are exercise rehabilitation and one drug, cilostazol. Pentoxifylline, which improves red cell deformability, lowers fibrinogen levels and decreases platelet aggregation, has been used historically, but frequency of use has declined because of limited effectiveness. Exercise rehabilitation, while efficacious, has been underused in the past. This therapy is, however, currently the subject of several large research projects. These studies are investigating mechanisms by which exercise therapy could benefit people with claudication and are also directly comparing it with other therapies. Concurrently, several new drug therapies for claudication are in the process of being evaluated. These research efforts might increase the available armamentarium and thereby help to alleviate the impairments associated with this symptom. The aim of this article is to discuss the current medical treatments being developed for use in patients with claudication resulting from peripheral arterial disease.

Upper- vs lower-limb aerobic exercise rehabilitation in patients with symptomatic peripheral arterial disease: A randomized controlled trial

OBJECTIVES

To investigate the effects of a 24-week program of upper- and lower-limb aerobic exercise training on walking performance in patients with symptomatic peripheral arterial disease (PAD) and to study the mechanisms that could influence symptomatic improvement.

METHODS

After approval from the North Sheffield Local Research Ethics Committee, 104 patients (median age, 69 years; range, 50 to 85 years) with stable PAD were randomized into an upper- or lower-limb aerobic exercise training group (UL-Ex or LL-Ex), or to a nonexercise training control group. Training was performed twice weekly for 24 weeks at equivalent relative exercise intensities. An incremental arm- and leg-crank test (ACT and LCT) to maximum exercise tolerance was performed before and at 6, 12, 18, and 24 weeks of the intervention to determine peak oxygen consumption (VO(2)). Walking performance, defined as the claudicating distance (CD) and maximum walking distance (MWD) achieved before intolerable claudication pain, was assessed at the same time points by using a shuttle-walk protocol. Peak blood lactate concentration, Borg ratings of perceived exertion (RPE) and pain category ratio (CR-10) were recorded during all assessments.

RESULTS

CD and MWD increased over time (P < .001) in both training groups. At 24 weeks, CD had improved by 51% and 57%, and MWD had improved by 29% and 31% (all P < .001) in the UL-Ex and LL-Ex groups, respectively. An increase in peak heart rate at MWD in the UL-Ex group (109 +/- 4 vs 115 +/- 4 beats/min; P < .01) and LL-Ex group (107 +/- 3 vs 118 +/- 3 beats/min; P = .01) was accompanied by an increase in the amount of pain experienced in both groups (P < .05), suggesting that exercising patients could tolerate a higher level of cardiovascular stress and an increased intensity of claudication pain before test termination after training. Patients assigned to exercise training also showed an increase in LCT peak VO2 at the 24-week time point in relation to baseline (P < .01) and control patients (P < .01), whereas ACT peak VO2 was only improved in the UL-Ex group (P < .05).

CONCLUSIONS

Our results suggest that a combination of physiologic adaptations and improved exercise pain tolerance account for the improvement in walking performance achieved through upper-limb aerobic exercise training in patients with PAD. Furthermore, that both arm- and leg-crank training could be useful exercise training modalities for improving cardiovascular function, walking performance, and exercise pain tolerance in patients with symptomatic PAD.

Cardiovascular training effect associated with polestriding exercise in patients with peripheral arterial disease

Because individuals with claudication pain secondary to peripheral arterial disease (PAD) are limited in both walking speed and duration, the benefits of walking exercise may be insufficient to yield a cardiovascular training effect. The objectives of this analysis were to determine whether polestriding exercise training, performed by persons with PAD, would improve exercise endurance, elicit a cardiovascular training benefit, and improve quality of life (QoL). Persons (n = 49) whose claudication pain limited their exercise capacity were randomized into a 24-week polestriding training program (n = 25, 65.8 +/- 7.1 years of age) or a nonexercise attention control group (n = 24, 68.0 +/- 8.6 years of age). Those assigned to the polestriding group trained 3 times weekly. Control group subjects came to the laboratory biweekly for ankle blood pressure measurements. A symptom-limited ramp treadmill test, ratings of perceived leg pain, and QoL data (using the Short Form-36) were obtained at baseline and upon completion of training. After 24 weeks of polestriding training, subjects increased their exercise endurance from 10.3 +/- 4.1 minute to 15.1 +/- 4.5 minute. This was significantly greater than control group subjects whose exercise endurance declined (from 11.2 +/- 4.7 to 10.3 +/- 4.7 minute; P < .001). Relationships between systolic blood pressure (P < .001), heart rate (P = .04), rate pressure product (P = .05), oxygen uptake (P = .016), and perceived leg pain (P = .02) and exercise time improved from the baseline symptom-limited treadmill test to the 6-month symptom-limited treadmill test in the polestriding group compared to the control group. The improvement in the physical component summary score of the Short Form-36 was also greater in the polestriding group (P = .031). Polestriding training significantly improved the clinical indicators of cardiovascular fitness and QoL, and decreased symptoms of claudication pain during exertion.

Validation of an angiographic method for estimating resting blood flow to distal tissue beds in the lower extremities

PURPOSE

The authors propose to validate an angiographic scoring system that estimates the resting blood flow in the lower extremities in patients with peripheral vascular disease (PVD).

MATERIALS AND METHODS

Twenty patients with PVD underwent lower-extremity angiography. For each patient, three readers used the proposed scheme to estimate flow within 23 separate vessel segments from the infrarenal aorta to the pedal vessels. Each reviewer scored each angiogram twice. The scheme includes not only an assessment of stenoses and occlusions but also corrections for collaterals. Flow reductions to muscles in the thigh and calf were calculated by multiplying the estimated flows in the series of vessels that lead to these regions. The consistency of the scoring scheme was assessed by calculating Pearson correlation coefficients for intra- and interobserver variability. The scoring scheme was also used to estimate the ankle-brachial index (ABI) and these estimates were compared to the known ABIs.

RESULTS

Overall, the scoring scheme demonstrated very good intra- and interobserver agreement. Correlation coefficients were typically greater than 0.9. In general, the correlation coefficients for proximal vessels were higher than those for distal vessels. The scoring scheme also had minimal intra- and interobserver variability for estimated flows to distal tissue beds. Agreement was better for a series of vessels than it was for individual segments. The estimated ABIs correlated well with the measured ABIs in all but two cases. These outliers include one case in which the measured ABI was >1 as a result of noncompressible vessels and the estimated ABI correctly reflected PVD. In the second case, the ABI was near normal because of a patent peroneal artery and our estimated ABI was abnormally low because our estimation method failed to factor in the peroneal artery.

CONCLUSIONS

The proposed angiography scoring system reproducibly estimated flow reductions to distal tissue beds. The authors plan to use this system as a research tool for evaluating new methods of assessing and treating PVD.

Treatment of peripheral arterial disease

Peripheral arterial disease (PAD) is a manifestation of systemic atherosclerosis strongly associated with cardiovascular (CV) morbidity and mortality. Approximately 12% of the US adult population is affected. Despite its prevalence, the disease has received little attention from clinicians. The primary causes of death in patients with PAD are myocardial infarction and stroke; thus, current treatment strategies for symptomatic PAD include aggressive modification of risk factors for CV disease such as cessation of smoking, treatment of hypertension and diabetes, and normalization of low-density lipoprotein cholesterol levels. All patients with PAD should be receiving antiplatelet therapy to prevent ischemic events. Medical treatment for patients with claudication includes exercise rehabilitation and drug therapy. Although many therapies for claudication have been thoroughly investigated, research continues on new treatments. In contrast, more prospective, randomized trials are needed to evaluate various therapies for treating patients with PAD.

The effects of exercise training on walking function and perception of health status in elderly patients with peripheral arterial occlusive disease

OBJECTIVE

To determine the effects of 12-week exercise programme on ambulatory function, free-living daily physical activity and health-related quality of life in disabled older patients with intermittent claudication.

DESIGN

Prospective, randomized controlled trial.

SETTING

University Medical Center and Veterans Affairs Medical Center, Taipei, Taiwan.

SUBJECTS

Thirty-two of 64 patients with Fontaine stage II peripheral arterial occlusive disease (PAOD) were randomized to exercise training and 32 to usual care control. Five patients from the exercise group and six patients from the control group dropped out, leaving 27 and 26 patients, respectively, completing the study in each group.

INTERVENTIONS

Twelve weeks of treadmill exercise training.

MAIN OUTCOME MEASURES

Treadmill walking time to onset of claudication pain and to maximal claudication pain, 6-min walk distance, self-reported ambulatory ability and perceived health-related quality of life (QOL).

RESULTS

Compliance of exercise programme was 83% of the possible sessions. Exercise training increased treadmill walking time to onset of claudication pain by 88% (P < 0.001), time to maximal pain by 70% (P < 0.001), and 6-min walk distance by 21% (P < 0.001).

SUBJECTS

Perception of health-related QOL improved from 12% to 178% in the exercise group. These improvements were significantly better than the changes in the control group (P < 0.05).

CONCLUSIONS

Significant improvements in claudication following 12-week exercise training in elderly PAOD patients were observed. Increase in treadmill walking time to maximal claudication pain in these patients translated into the improvement of perceived physical health, which enabled the patients to become more functionally independent.

Muscle ischaemia in rats may be relieved by overload-induced angiogenesis

Alleviation of muscle ischaemia by improving capillary supply has proved difficult, possibly reflecting the inability to substantially increase blood flow. We reasoned that muscle overload, which induces angiogenesis in the absence of altered blood flow, may be an alternative to drug therapy. Male Wistar rats underwent unilateral ligation of the common iliac artery, with or without ipsilateral extirpation of the tibialis anterior muscle. Six weeks later ischaemic (I) extensor digitorum longus (EDL) had a 10% (P < 0.05) decrease in relative muscle mass, while overloaded muscles (O) had undergone hypertrophy of 39% and 52% relative to contralateral (CL) and control (C) muscle masses, respectively (P < 0.01). Muscle atrophy was prevented by the combination of overload and ischaemia (O/I), with hypertrophy of 24% (vs. CL) and 35% (vs. C), respectively (P < 0.01). Changes in muscle fibre cross-sectional area paralleled the changes in muscle mass, with means of 1898 +/- 59, 1531 +/- 90, 2253 +/- 155 and 2292 +/- 80 mm2 for C, I, O and O/I, respectively (P < 0.01 vs. C and I). Capillary to fibre ratio (C:F) was significantly increased in overloaded (2.58 +/- 0.09) compared to contralateral (1.78 +/- 0.04), control (1.61 +/- 0.05) and ischaemic (1.73 +/- 0.06) muscles (P < 0.001). A similar increase in C:F was seen in overloaded plus ischaemic muscle (2.59 +/- 0.07) compared to contralateral (1.40 +/- 0.01) and control or ischaemic values (P < 0.01). In both O and O/I muscle groups, C:F and capillary density (CD) increased most in the region of EDL where fibre size was largest, while hypertrophy of fibres was least in the same region for both groups. These data suggest that the microvascular deficit evident in chronic muscle ischaemia may be alleviated by angiogenesis that is induced by mechanical stimuli via chronic muscle overload.

Effects of long-term exercise rehabilitation on claudication distances in patients with peripheral arterial disease: a randomized controlled trial

PURPOSE

To determine if improvements in physical function and peripheral circulation after 6 months of exercise rehabilitation could be sustained over a subsequent 12-month maintenance exercise program in older patients with intermittent claudication.

METHODS

Seventeen patients randomized to exercise rehabilitation and 14 patients randomized to usual care control completed this 18-month study. Patients exercised three times per week during the first 6 months of a progressive exercise program, followed by two times per week during the final 12 months of a maintenance program. Patients were studied at baseline, 6 months, and 18 months during the study.

RESULTS

Eighteen months of exercise rehabilitation increased the initial claudication distance by 373 meters (189%) (P <.001), the absolute claudication distance by 358 meters (80%) (P <.001), walking economy by 11% (P <.001), 6-minute walk distance by 10% (P <.001), daily physical activity by 31%, and maximal calf blood flow by 18% (P <.001). These changes were similar to those found after 6 months of exercise rehabilitation (P = NS), and were significantly greater than the changes in the control group throughout the study (P <.05).

CONCLUSION

Improvements in claudication distances, walking economy, 6-minute walk distance, physical activity level, and peripheral circulation after 6 months of exercise rehabilitation are sustained for an additional 12 months in older patients with intermittent claudication using a less frequent exercise maintenance program.

Haemodynamic limitations and exercise performance in peripheral arterial disease

It has been frequently argued that haemodynamic limitations are poor predictors of exercise performance in people with peripheral arterial disease (PAD) and intermittent claudication. This review has tried to address this argument through a review of published data that appears to support or counterbalance it, brief consideration of some of the methodological limitations associated with these data, as well as some other considerations. The main argument rests primarily upon data about the resting ankle-brachial index (ABI) and/or blood flow after calf exercise or an ischaemic challenge; whereas the counter argument rests mainly on data about blood flow during walking or cyding exercise. Consideration of the limitations of all methods suggests that the measurement of blood flow during exercise has the greatest value in explaining differences in exercise performance amongst claudicants; whereas the other methods are relatively limited in their explanatory value. This strengthens the counter argument and undermines the main argument proposed by others. Consequently, asserting that haemodynamic limitations are poor predictors of exercise performance in claudicants is not justified in light of available evidence.

Current medical therapies for patients with peripheral arterial disease: a critical review

There is a paucity of trials that specifically evaluate the benefits of cardiovascular risk reduction therapies in patients with peripheral arterial disease. We therefore sought to describe the data supporting the use of therapies for lowering cardiovascular risk, preventing ischemic events, as well as managing intermittent claudication, in these patients. A search for randomized, placebo-controlled trials in peripheral arterial disease was conducted using Medline and reference lists of relevant articles. These trials served as the primary sources of data and treatment recommendations, while observational studies and case series were included as sources of commonly accepted treatment recommendations that were not fully supported by the randomized trial. Data from the primary sources support the use of antiplatelet therapy and, potentially, of angiotensin-converting enzyme inhibitors, for preventing ischemic events. In contrast, the evidence demonstrates a nonsignificant trend for treating dyslipidemia to prevent mortality and does not specifically support intensive glycemic control in persons with diabetes or estrogen use in these patients. However, observational data and data derived from trials in persons with other manifestations of cardiovascular disease may be generalized to support the importance of treating key risk factors, such as smoking, diabetes, dyslipidemia, and hypertension. Data supporting the use of estrogen to reduce cardiovascular risk are less clear. Studies do demonstrate improvement in walking ability resulting from exercise rehabilitation programs, as well as from use of cilostazol and, to a more modest degree, pentoxifylline. The consensus is to treat risk factors of peripheral arterial disease patients similarly to patients with other manifestations of atherosclerosis and to use exercise rehabilitation or cilostazol to treat the subset of patients with claudication.

Improvement of peripheral and cardiopulmonary performance after a short-term exercise program with additive prostaglandin E1

In patients with intermittent claudication, the walking distance can be increased, both by means of several months of intensive training and administration of IV prostaglandin E1 (PGE1) for 4 weeks. The aim of this study was, therefore, to investigate whether the combination of intensive training and PGE1 infusions during pedalergometry can increase peripheral and cardiopulmonary performance after 2 weeks. Ten patients with intermittent claudication received a once-daily intravenous infusion of 60 microg PGE1 over 2 hours during pedalergometry. In addition, a physical training program was carried out mornings and afternoons, as well as progressive treadmill training. Walking distance (3 km/h, 12%) and cardiopulmonary performance were determined at the beginning and end of the 2-week treatment. Results were compared with those of a historical control group having received a similar training program without PGE1. The initial walking distance increased from 71 to 166 m (134%). At the same time, peak work load increased by 108%, and the physical work capacity by 100%. Cardiopulmonary function improvement was reflected in all the parameters investigated (peak VO2; peak VO2/peak work load ratio; slope of deltaVO2/deltat; RER). Compared with the historical control group, the difference between the two groups with regard to the increase in walking distance was significant in favor of the combined training program with PGE1. The combination of short-term intensive training and PGE1 infusions during pedal ergometry significantly improves both the peripheral as well as the highly restricted functional capacity in patients with intermittent claudication.

Exercise rehabilitation improves functional outcomes and peripheral circulation in patients with intermittent claudication: a randomized controlled trial

OBJECTIVE

To determine the effects of a 6-month exercise program on ambulatory function, free-living daily physical activity, peripheral circulation, and health-related quality of life (QOL) in disabled older patients with intermittent claudication.

DESIGN

Prospective, randomized controlled trial.

SETTING

University Medical (Center and Veterans Affairs Medical Center, Baltimore, Maryland.

PARTICIPANTS

Thirty-one of 61 patients with Fontaine stage II peripheral arterial occlusive disease (PAOD) were randomized to exercise rehabilitation and 30 to usual-care control. Three patients from the exercise group and six patients from the control group dropped out, leaving 28 and 24 patients, respectively, completing the study in each group.

INTERVENTION

Six months of exercise rehabilitation.

MEASUREMENTS

Treadmill distance walked to onset of claudication and to maximal claudication, ambulatory function, peripheral circulation, perceived QOL, and daily physical activity.

RESULTS

Compliance with the exercise program was 73% of the possible sessions. Exercise rehabilitation increased treadmill distance walked to onset of claudication by 134% (P < .001) and to maximal claudication by 77% (P < .001), walking economy by 12% (P = .003), 6-minute walk distance by 12% (P < .001), and maximal calf blood flow by 30% (P < .001). Changes in distance walked to maximal pain correlated with changes in walking economy (r = -.50, P = .013) and changes in maximal calf blood flow (r = .38, P = .047). Exercise rehabilitation increased accelerometer-derived daily physical activity by 38% (P < .001); this change correlated with the change in distance walked to maximal pain (r = .45, P = .020). These improvements were significantly better than the changes in the control group (P < .05).

CONCLUSION

Improvements in claudication following exercise rehabilitation in older PAOD patients are dependent on improvements in peripheral circulation and walking economy. Improvement in treadmill claudication distances in these patients translated into increased accelerometer-derived physical activity in the community, which enabled the patients to become more functionally independent.

Improved functional outcomes following exercise rehabilitation in patients with intermittent claudication

BACKGROUND

The purposes of this study were to identify predictors of increased claudication distances following exercise rehabilitation in peripheral arterial occlusive disease (PAOD) patients with intermittent claudication and determine whether improved claudication distances translated into increased free-living daily physical activity in the community setting.

METHODS

Sixty-three patients were recruited (age, 68+/-1 years, mean +/- standard error). Patients were characterized on treadmill claudication distances, walking economy, peripheral circulation, cardiopulmonary function, self-perceived ambulatory function, body composition, baseline comorbidities, and free-living daily physical activity before and after a 6-month treadmill exercise program.

RESULTS

Exercise rehabilitation increased distance to onset of claudication pain by 115% (178+/-22 m to 383+/-34 m; p < .001) and distance to maximal claudication pain by 65% (389+/-29 m to 641+/-34 m; p < .001). The increased distance to onset of pain was independently related to a 27% increase in calf blood flow (r = .42, p < .001) and to baseline age (r = -.26, p < .05), and the increased distance to maximal pain was predicted by a 10% increase in peak oxygen uptake (r = .41, p < .001) and by a 10% improvement in walking economy (r = -.34, p < .05). Free-living daily physical activity increased 31% (337+/-29 kcal/day to 443+/-37 kcal/day; p < .001) and was related to the increases in treadmill distances to onset (r = .24, p < .05) and to maximal pain (r = .45, p < .001).

CONCLUSIONS

Increased claudication distances following exercise rehabilitation are mediated through improvements in peripheral circulation, walking economy, and cardiopulmonary function, with younger patients having the greatest absolute ambulatory gains. Furthermore, improved symptomatology translated into enhanced community-based ambulation.

Investigation of perfusion reserve using 99Tc(m)-MIBI in the lower limbs of diabetic patients

This study aimed to investigate the microvascular pathology in the lower limbs of diabetic patients without symptoms or findings of peripheral ischaemia by measuring perfusion reserve scintigraphically. It was carried out in 47 female subjects who had no evidence of peripheral arterial disease in their history, physical examination or Doppler ultrasonography. The diabetic group consisted of 25 women (mean age 54.2 +/- 3.54 years) with type II diabetes mellitus of more than 10 years' duration. A control group consisted of 22 healthy non-diabetic women (mean age 50.14 +/- 6.75 years). Each subject flexed their right foot maximally both dorsally and plantar 60 times. In the middle of this exercise, 370 MBq technetium-99m-methoxyisobutylisonitrile (99Tc(m)-MIBI) was injected intravenously. Ten minutes after the injection, a posterior image of both calves was obtained using a gamma camera. Rectangular regions of interest were symmetrically drawn over both calves. The total count in the resting calf was subtracted from the total count in the exercising calf, and the percentage increase, termed the perfusion reserve, was determined. A significant difference was found between the perfusion reserves of the diabetic and control groups (76.04 +/- 12.96% and 95.91 +/- 12.83%, respectively; P<0.001). In conclusion, microvascular pathology may be determined scintigraphically by measuring the perfusion reserve in the lower limb muscles in diabetic patients. This method may also be used to evaluate perfusion abnormalities in other circulatory disorders.

Exercise therapy or angioplasty? A summation analysis

OBJECTIVES

To compare the outcome of exercise therapy or angioplasty for the treatment of patients with intermittent claudication.

DESIGN

A summation analysis.

METHODS

A search using MEDLINE and PUBMED between 1966 and April 1999 followed by a review of the manuscripts yielded 54 studies involving angioplasty and 27 studies involving exercise therapy for intermittent claudication. Studies were only included (12 angioplasty and nine exercise series) when results were available for patients with intermittent claudication alone, and when outcome was assessed in terms of symptoms at a minimum of 6 months.

RESULTS

The total number of claudicants undergoing exercise therapy was 294 patients, with a mean symptomatic success rate of 38. 4% and a mean improvement in maximum walking distance of 189.7% at 6 months. The total number of claudicants undergoing angioplasty was 2071, with a mean overall symptomatic success rate of 76.6%. The mean overall complication rate was 9% and mean major complication rate was 2.7% for the angioplasty studies.

CONCLUSION

Although the result demonstrates an advantage of angioplasty over exercise therapy at 6 months, there is a small risk of major complications. However, comparison of studies was impaired due to disparity in patient numbers, limited follow-up time and lack of uniformity in outcome assessment. In order to achieve a valid comparison of these therapies in a future randomised study, a validated disease-specific instrument for the assessment of symptomatic outcome for claudicants is required.

Comorbidities and the entry of patients with peripheral arterial disease into an exercise rehabilitation program

BACKGROUND

Exercise rehabilitation is advocated to improve function in patients with peripheral arterial disease (PAD) who have intermittent claudication. Patients with PAD often have comorbid medical problems that may interfere with their ability to safely participate in exercise rehabilitation programs. There is a paucity of information regarding the medical comorbidities and the evaluation of PAD patients before their participation in exercise rehabilitation studies. The purpose of this study was to identify comorbidities that predicted exclusion of PAD patients from participation in an aerobic exercise rehabilitation clinical trial.

METHODS

This was a prospective cohort study of 225 consecutive outpatient volunteers (mean age 68 +/- 8 years, SD) with a history of Fontaine Stage II PAD recruited for exercise rehabilitation. Patient eligibility was determined by a history and physical exam, blood chemistries, measurement of ankle to brachial index (ABI), and an exercise treadmill test.

RESULTS

Seventy-nine volunteers (35%) were medically ineligible: 22 because of symptomatic coronary artery disease, 12 because of severe PAD, and the rest for a variety of medical problems. In stepwise logistic regression analyses, low ABI and use of insulin were predictors of exclusion, whereas peripheral revascularization was an indicator of inclusion. Age, a history of coronary artery disease, myocardial infarction, coronary bypass surgery, and hypertension were not independent determinants of eligibility.

CONCLUSIONS

Insulin-requiring diabetes and a low ABI increase the likelihood that older patients with PAD will be ineligible to participate in a research exercise rehabilitation program, whereas peripheral revascularization was associated with inclusion. Whether intensive medical management and peripheral revascularization would enable the claudicants deemed ineligible for entry into the exercise rehabilitation program to safely exercise remains to be determined.

Exercise training and peripheral vascular disease

BACKGROUND

Conservative management is advocated as a treatment of choice for patients with intermittent claudication. This is a review of the mechanisms behind the improvement following an exercise rehabilitation programme.

METHODS

All Medline articles from the National Library of Medicine, USA containing the text words 'claudication' or 'peripheral vascular disease' and 'exercise' were reviewed. Cross-referencing from relevant articles was carried out.

RESULTS AND CONCLUSION

The poor physical status of a patient with intermittent claudication is not solely due to a reduction in blood flow to the lower limbs; associated factors, such as metabolic inefficiency, poor cardiorespiratory reserve and exercise-induced inflammation contribute. An exercise programme frequently improves both the physical aspect and quality of life, and the success of such exercise is multifactorial. An increase in the blood flow to the lower extremity is uncommon. Other factors, such as a redistribution of blood flow, changes in oxidative capacity of the skeletal muscles and greater utilization of oxygen, occur and the associated metabolic dysfunction of the skeletal muscles is rectified. Following exercise training, blood rheology improves and exercise-induced inflammation is ameliorated; cardiorespiratory status also benefits and the oxygen cost of exercise decreases.

bFGF increases collateral blood flow in aged rats with femoral artery ligation

We tested the hypothesis that aged animals are as responsive as the young adult animals in expanding collateral vasculature under a similar treatment of basic fibroblast growth factor (bFGF). Two age groups of male Fischer 344 rats (11 mo old; n = 32, 23 mo old; n = 43) weighing approximately 385 g were subdivided into normal, acute ligation [femoral artery (FA) ligated 3 days before blood flow (BF) measurement] or ligated groups for 16 days and received recombinant human bFGF intra-arterial infusion at doses of 0, 0.5, 5, and 50 microg x kg(-1) x day(-1). BF was determined with (85)Sr- and (141)Ce-labeled microspheres during treadmill running at 15 and 20 m/min at 15% grade. Blood pressure (BP) values were approximately 149 and approximately 163 mmHg (p < 0.05); heart rates were approximately 496 and approximately 512 beats/min in the aged and young adult groups during running, respectively. Maximal collateral BF values were confirmed by no additional BF increase in the calf muscle at the higher speed. Ligation of the FA for 3 days reduced the BF reserve to the calf muscle by approximately 90%. Calf muscle BF was modestly greater (10 ml x min(-1) x 100 g(-1)) by 16 days in the carrier group. bFGF infusion expanded collateral BF in a dose-dependent manner with an increase of 33 and 42 ml x min(-1) x 100 g(-1) (P < 0.001) in the 5 and 50 microg x kg(-1) x day(-1) bFGF groups, respectively. Aged animals showed similar BF improvements as observed with the adult groups in response to ligation surgery and bFGF treatment. Our data indicate that the aged rats (approximately 23 mo old) remain responsive to exogenous bFGF induced in developing collateral-dependent BF as the young adult (approximately 11 mo old) controls. This suggests that the influence of bFGF in expanding collateral BF should not be preempted in the aged group, the population most affected by peripheral arterial insufficiency.

Relieving intermittent claudication: a nursing approach

Peripheral arterial disease affects at least 10% of adults older than 70 years. Risk factors such as diabetes, hypertension, hyperlipidemia, history of smoking, and genetics increase the incidence of the disease. Intermittent claudication, experienced as calf pain or cramping, is the primary symptom in patients with lower-extremity peripheral arterial disease. Patients with claudication are unable to walk even moderate distances. As a result, they often lead lives that are profoundly restricted. Medical therapeutic options available for patients with intermittent claudication are limited to a small number of medications and walking exercise rehabilitation. Walking exercise training can significantly increase ability and decrease calf discomfort for many patients. Nurses can have a major impact on improving the quality of life of patients with claudication, not only by seeking referrals to established institutional walking exercise programs, but also by helping patients in the community develop a personalized walking program. In this article, a nursing plan of care including short-term and long-term goals is addressed. A case study will illustrate the effectiveness and improved quality of life that an individualized program of walking exercise had for one community-based client.

Exercise stimulates neovascularization in occluded muscle without affecting bFGF content

PURPOSE

This study was conducted to determine whether exercise-induced improvements in capillarity in muscle with peripheral arterial insufficiency (PAI) was accompanied by endothelial cell mitosis, and whether that response could be explained by changes in the expression of basic fibroblast growth factor (bFGF), a known mitogen.

METHODS

After bilateral ligation of femoral arteries, Sprague-Dawley rats either remained sedentary or participated in a treadmill running protocol. Running time to exhaustion at each session was recorded. On days 1, 2, 3, 5, and 7 of the experimental period, trained-ligated and sedentary-ligated animals were euthanized, and segments of muscle from the gastrocnemius were obtained. Capillarity was determined with histochemistry, and endothelial cell mitotic activity (cell proliferation) was assayed via nuclear uptake of 5'-bromo-2'-deoxyuridine (BrdU), an analog of thymidine. Content of endogenous bFGF was assessed with immunoblotting techniques.

RESULTS

Exercise training resulted in augmented function of PAI affected muscle as evidenced by a nearly threefold increase in running time until exhaustion. Trained-ligated muscle demonstrated significantly (P < 0.05) greater capillarity than sedentary-ligated muscle. Vascular remodeling elicited by exercise included the formation of new capillaries (angiogenesis) as indicated by enhanced endothelial cell proliferation at days 3, 5, and 7 of the study. However, exercise training did not alter the content of bFGF in occluded muscle.

CONCLUSION

In muscle with PAI, exercise training improved functional capacity and capillarity. Angiogenesis was confirmed by the increased mitotic activity of endothelial cells. However, the content of bFGF, a potent angiogenic factor, was not altered. Thus, exercise-induced angiogenesis in PAI affected muscle is not dependent upon increased expression of endogenous bFGF.

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

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

Exercise testing and exercise rehabilitation for patients with peripheral arterial disease: status in 1997

Intermittent claudication is a common manifestation of peripheral arterial occlusive disease (PAOD). Patients with claudication are limited in terms of work, housework and leisure activities so that functional status is very impaired. Therefore, the goals for treatment should focus on improving the functional impairment as well as on modifying risk factors. Evaluation of the functional status is of critical importance before beginning any therapy so that any resultant changes can be assessed. A validated graded treadmill protocol and validated questionnaires are used for this purpose. Three questionnaires that are currently used include the Walking Impairment Questionnaire, the PAOD Physical Activity Recall and the Medical Outcomes Study SF-36. Exercise rehabilitation is a method that has been particularly efficacious for treating the functional impairment associated with intermittent claudication. Exercise rehabilitation has been shown to improve pain-free treadmill walking distance by 44% to 300% and absolute walking distance by 25% to 442%. In addition, improvements have also been reported (using questionnaire data) in the ability to walk distances and speeds, in amount of habitual physical activity and in physical functioning. Thus, exercise rehabilitation has caused improvements not only in exercise capacity but also in community-based functional status. Because of the benefits of this treatment, in addition to the low associated morbidity, exercise therapy is recommended as an important treatment option for people with intermittent claudication due to PAOD.