Pain Threshold Is Achieved at Intensity Above Anaerobic Threshold in Patients With Intermittent Claudication

Physiological responses during walking in men and women with intermittent claudication

BACKGROUND

Miyasato et al. show that peak oxygen consumption, walking economy, anaerobic threshold, and cardiovascular responses (heart rate, blood pressure, and rate pressure product) during walking were similar between men and women with peripheral artery disease and intermittent claudication. There were no differences in the physiological responses to walking between men and women with intermittent claudication. Sex per se is not a factor that demands changes in walking prescription for patients with intermittent claudication.

OBJECTIVE

Peak oxygen consumption (VO2peak), anaerobic threshold, walking economy, and cardiovascular responses during walking are used to guide and monitor walking training in patients with peripheral artery disease and intermittent claudication. Women with peripheral artery disease and intermittent claudication present greater impairments than men, and evaluating training markers according to sex for decisions regarding walking prescription in this population is important. This study aimed to compare VO2peak, walking economy, anaerobic threshold, and cardiovascular responses during walking in men and women with peripheral artery disease and intermittent claudication.

METHODS

Forty patients (20 men and 20 women with similar baseline characteristics) underwent a cardiopulmonary treadmill test (3.2km/h and 2% increase in slope every 2 minutes until maximal leg pain). The VO2 and rate-pressure product were assessed. Data from men and women were compared using t-tests.

RESULTS

There were no significant differences between men and women (VO2peak: 15.0±4.8 versus 13.9±2.9mL∙kg-1∙min-1, p=0.38; walking economy: 9.6±2.7 versus 8.4±1.6mL∙kg-1∙min-1, p=0.09; anaerobic threshold: 10.5±3.2 versus 10.5±2.2mL∙kg-1∙min-1, p=0.98; rate pressure product at 1st stage: 13,465± 2,910 versus 14,445±4,379bpm∙mmHg, p=0.41; and rate pressure product at anaerobic threshold:13,673±3,100 versus 16,390±5,870bpm∙mmHg, p=0.08 and rate pressure product at peak exercise: 21,253±6,141 versus 21,923±7,414bpm∙mmHg, p=0.76, respectively).

CONCLUSION

Men and women with peripheral artery disease and similar baseline characteristics presented similar responses to walking, suggesting that decisions regarding walking prescription and monitoring can be made regardless of sex in this specific population.

Skeletal muscle capillary density is related to anaerobic threshold and claudication in peripheral artery disease

Peripheral artery disease (PAD) is characterized by impaired blood flow to the lower extremities, causing claudication and exercise intolerance. Exercise intolerance may result from reduced skeletal muscle capillary density and impaired muscle oxygen delivery. This cross-sectional study tested the hypothesis that capillary density is related to claudication times and anaerobic threshold (AT) in patients with PAD. A total of 37 patients with PAD and 29 control subjects performed cardiopulmonary exercise testing on a treadmill for AT and gastrocnemius muscle biopsies. Skeletal muscle capillary density was measured using immunofluorescence staining. PAD had decreased capillary density (278 ± 87 vs 331 ± 86 endothelial cells/mm², p = 0.05), peak VO₂ (15.7 ± 3.9 vs 24.3 ± 5.2 mL/kg/min, p ⩽ 0.001), and VO₂ at AT (11.5 ± 2.6 vs 16.1 ± 2.8 mL/kg/min, p ⩽ 0.001) compared to control subjects. In patients with PAD, but not control subjects, capillary density was related to VO₂ at AT (r = 0.343; p = 0.038), time to AT (r = 0.381; p = 0.020), and time after AT to test termination (r = 0.610; p ⩽ 0.001). Capillary density was also related to time to claudication (r = 0.332; p = 0.038) and time after claudication to test termination (r = 0.584; p ⩽ 0.001). In conclusion, relationships between capillary density, AT, and claudication symptoms indicate that, in PAD, exercise limitations are likely partially dependent on limited skeletal muscle capillary density and oxidative metabolism.

Exercise Intensity during 6-Minute Walk Test in Patients with Peripheral Artery Disease

BACKGROUND

Non-supervised ground walking has been recommended for patients with symptomatic peripheral artery disease (PAD). However, the magnitude of the effort required by this activity and the characteristics of patients whose ground walking is more intense are unclear.

OBJECTIVES

To determine whether ground walking exceeds the ventilatory threshold (VT), a recognized marker of exercise intensity, in patients with symptomatic PAD.

METHODS

Seventy patients (61.4% male and aged 40 to 85 years old) with symptomatic PAD were recruited. Patients performed a graded treadmill test for VT determination. Then, they were submitted to a 6-minute walk test so the achievement of VT during ground ambulation could be identified. Multiple logistic regression was conducted to identify predictors of VT achievement during the 6-minute walk test. The significance level was set at p < 0.05 for all analyses.

RESULTS

Sixty percent of patients achieved VT during the 6-minute walk test. Women (OR = 0.18 and 95%CI = 0.05 to 0.64) and patients with higher cardiorespiratory fitness (OR = 0.56 and 95%CI = 0.40 to 0.77) were less likely to achieve VT during ground walking compared to men and patients with lower cardiorespiratory fitness, respectively.

CONCLUSION

More than half of patients with symptomatic PAD achieved VT during the 6-minute walk test. Women and patients with higher cardiorespiratory fitness are less likely to achieve VT during the 6-minute walk test, which indicates that ground walking may be more intense for this group. This should be considered when prescribing ground walking exercise for these patients. (Arq Bras Cardiol. 2020; 114(3):486-492).

Barriers and Levels of Physical Activity in Patients With Symptomatic Peripheral Artery Disease: Comparison Between Women and Men

This cross-sectional study compared physical activity levels and barriers between 212 men and women with symptomatic peripheral artery disease. Physical activity was objectively measured by an accelerometer. Barriers to physical activity were obtained using a validated questionnaire. Women reported higher amounts of light physical activity (p < .001) and lower moderate-vigorous physical activity (p < .001) than men. Women more often reported barriers such as "not having anyone to accompany" (p = .006), "lack of money" (p = .018), "fear of falling or worsening the disease" (p = .010), "lack of security" (p = .015), "not having places to sit when feeling leg pain" (p = .021), and "difficulty in getting to a place to practice physical activity" (p = .015). In conclusion, women with symptomatic peripheral artery disease presented with lower amounts of moderate-vigorous activity and more barriers to activity than men. Strategies to minimize the barriers, including group actives and nonpainful exercises, are recommended for women with peripheral artery disease.

Clinical predictors of ventilatory threshold achievement in patients with claudication

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Exercise prescription using the heart of claudication pain onset in patients with intermittent claudication

OBJECTIVE

To assess the acute metabolic and cardiovascular responses to walking exercise at an intensity corresponding to the heart rate of claudication pain onset and to investigate the effects of a 12-week walking training program at this intensity on walking capacity.

METHODS

Twenty-nine patients with intermittent claudication were randomly allocated to the walking training (n=17) or control (CO, n=12) group. The walking training group performed an acute exercise session comprising 15×2-min bouts of walking at the heart rate of claudication pain onset, with 2-min interpolated rest intervals. The claudication symptoms and cardiovascular and metabolic responses were evaluated. Walking training was then performed at the same intensity twice each week for 12 weeks, while the control group engaged in twice weekly stretching classes. The claudication onset distance and total walking distance were evaluated before and after the interventions. Brazilian Registry Clinical Trials: RBR-7M3D8W.

RESULTS

During the acute exercise session, the heart rate was maintained within tight limits. The exercise intensity was above the anaerobic threshold and >80% of the heart rate peak and VO2peak. After the exercise training period, the walking exercise group (n=13) showed increased claudication onset distance (309±153 vs. 413±201m) and total walking distance (784±182 vs. 1,100±236m) compared to the control group (n=12) (p<0.05).

CONCLUSION

Walking exercise prescribed at the heart rate of claudication pain onset enables patients with intermittent claudication to exercise with tolerable levels of pain and improves walking performance.

Triagem pré-participação em exercício físico em pacientes com doença arterial periférica

CONTEXTO: Os indivíduos com doença arterial periférica (DAP) apresentam alto risco de doença cardiovascular. Dessa forma, é imprescindível que os instrumentos de triagem pré-participação em exercício indiquem quais pacientes com DAP devem realizar avaliação cardiovascular antes de iniciar o programa de exercício. OBJETIVO: Comparar a sensibilidade de dois instrumentos de triagem pré-participação em exercício para identificação de indivíduos com DAP. MÉTODOS: Vinte e oito pacientes com DAP de ambos os sexos responderam ao questionário de prontidão para a atividade física (PAR-Q) e um questionário de estratificação do risco cardiovascular (QERC) baseado nas diretrizes do American College of Sports Medicine. RESULTADOS: O PAR-Q mostrou que a questão seis (Algum médico já recomendou o uso de medicamentos para a sua pressão arterial ou condição cardiovascular?) foi a que apresentou maior frequência de respostas positivas (82,1%). Considerando todas as respostas, cinco indivíduos não tiveram nenhuma positiva ao questionário (17,9%), indicando que estariam aptos para a prática de atividade física. Os resultados do QERC mostraram que as questões 11 (Você sente queimação ou sensação de câimbras em suas pernas quando faz caminhada?) e 2 (Algum médico já falou que você tem pressão alta?) apresentaram a maior frequência de respostas positivas (82,1%). CONCLUSÕES: Segundo o QERC, todos os indivíduos da amostra foram considerados com alto risco cardiovascular. O PAR-Q não foi sensível o suficiente para identificar todos os sujeitos, ao passo que o QERC identificou todos os indivíduos. Assim, sugere-se a utilização do QERC para identificação de indivíduos com DAP.

Reliability of the Baltimore Activity Scale Questionnaire for Intermittent Claudication

We assessed the reliability of the Baltimore Activity Scale for Intermittent Claudication (BASIC) for the evaluation of physical activity levels in individuals with intermittent claudication. We also identify the characteristics of the patients that influence the reliability of this questionnaire. A total of 38 men and women with peripheral artery disease and symptoms of intermittent claudication participated in the study. BASIC was administered to patients by the same evaluator at 2 different visits, separated by 7 days. The concordance coefficient ranged from .43 (How often do you walk at a fast pace?) to .85 (What happens when you feel pain while you walk?). The concordance coefficient of BASIC total score was .60. Higher concordance coefficients were observed in women (.66 vs .55), in younger patients (.63 vs .56), and in patients with lower ankle-brachial index (.64 vs .55). The reliability of BASIC questionnaire ranged from moderate to good in patients with claudication.