Interval training based on ventilatory anaerobic threshold improves aerobic functional capacity and metabolic profile: a randomized controlled trial in coronary artery disease patients.

BACKGROUND: Exercise training has been an essential component of cardiac rehabilitation. However, it is not known if interval training (IT) based on the ventilatory anaerobic threshold (VAT) could be effective in improving aerobic functional capacity and metabolic profile in patients without or with coronary artery disease (CAD). AIM: To investigate the effects of an IT program, based-intensity between 70-110% of workload reached at the VAT, on the aerobic functional capacity and metabolic profile of patients with and without CAD. DESIGN: Randomized controlled trial. SETTING: Outpatients from a cardiac rehabilitation. POPULATION: A sample was composed of 32 patients with CAD (CAD group) and 32 patients without CAD (noCAD group) that were randomized into a trained or control groups. METHODS: Submaximal cardiopulmonary exercise test on the cycle ergometer and blood samples were realized at baseline and post 16 weeks of IT program. The cardiorespiratory variables were obtained at the VAT level. Trained groups (CAD-T, N.=15; noCAD-T, N.=15) underwent a supervised three-week session IT program (30-40 minutes each exercise session, at the intensity workloads equivalent to %VAT [70-110%]) for 16 weeks. RESULTS: After 16 weeks of IT program, there were a significant increase of VO(2VAT) and workload in the trained groups (P<0.05), while in the control groups VO(2VAT) and heart rate decreased (P<0.05). Body mass and body index mass decreased in trained groups (P<0.05), and low-density lipoprotein increased only in noCAD group after 16 weeks (P<0.05). The magnitude of the improvement in VO(2VAT) was related to VO(2VAT) (r=-0.57, P<0.05) and workload (r=-0.52, P<0.05) at baseline. CONCLUSION: The IT program prescribed with intensities based on VAT improved the aerobic functional capacity and decreased body mass and body index mass loss in patients with and without CAD. CLINICAL REHABILITATION IMPACT: IT program based on VAT provides new possibilities for cardiac rehabilitation in relation to individualized exercise prescription of the interval training.

Interval training based on ventilatory anaerobic threshold increases cardiac vagal modulation and decreases high-sensitivity c-reative protein: randomized clinical trial in coronary artery disease.

BACKGROUND: Autonomic dysfunction and inflammatory activity are involved in the development and progression of coronary artery disease (CAD), and exercise training has been shown to confer a cardiovascular benefit. OBJECTIVE: To evaluate the effects that interval training (IT) based on ventilatory anaerobic threshold (VAT) has on heart rate variability (HRV) and high-sensitivity C-reactive protein (hs-CRP) levels, as well as the relationship between both levels, in patients with CAD and/or cardiovascular risk factors (RF). METHOD: Forty-two men (aged 57.88±6.20 years) were divided into two training groups, CAD-T (n= 12) and RF-T (n= 10), and two control groups, CAD-C (n= 10) and RF-C (n=10). Heart rate and RR intervals in the supine position, cardiopulmonary exercise tests, and hs-CRP levels were measured before and after IT. HRV was analyzed by spectral and symbolic analysis. The CAD-T and RF-T underwent a 16-week IT program of three weekly sessions at training intensities based on the VAT. RESULTS: In the RF-T, cardiac sympathetic modulation index and hs-CRP decreased (p<0.02), while cardiac parasympathetic modulation index increased (p<0.02). In the CAD-T, cardiac parasympathetic modulation index increased, while hs-CRP, systolic, and diastolic blood pressures decreased (p<0.02). Both control groups showed increase in hs-CRP parameters (p<0.02). There was a strong and significant association between parasympathetic and sympathetic modulations with hs-CRP. CONCLUSION: The IT program based on the VAT promoted a decrease in hs-CRP associated with improvement in cardiac autonomic modulation.

Interval training based on ventilatory anaerobic threshold increases cardiac vagal modulation and decreases high-sensitivity c-reative protein: randomized clinical trial in coronary artery disease

Background: Autonomic dysfunction and inflammatory activity are involved in the development and progression of coronary artery disease (CAD), and exercise training has been shown to confer a cardiovascular benefit. Objective: To evaluate the effects that interval training (IT) based on ventilatory anaerobic threshold (VAT) has on heart rate variability (HRV) and high-sensitivity C-reactive protein (hs-CRP) levels, as well as the relationship between both levels, in patients with CAD and/or cardiovascular risk factors (RF). Method: Forty-two men (aged 57.88±6.20 years) were divided into two training groups, CAD-T (n= 12) and RF-T (n= 10), and two control groups, CAD-C (n= 10) and RF-C (n=10). Heart rate and RR intervals in the supine position, cardiopulmonary exercise tests, and hs-CRP levels were measured before and after IT. HRV was analyzed by spectral and symbolic analysis. The CAD-T and RF-T underwent a 16-week IT program of three weekly sessions at training intensities based on the VAT. Results: In the RF-T, cardiac sympathetic modulation index and hs-CRP decreased (p<0.02), while cardiac parasympathetic modulation index increased (p<0.02). In the CAD-T, cardiac parasympathetic modulation index increased, while hs-CRP, systolic, and diastolic blood pressures decreased (p<0.02). Both control groups showed increase in hs-CRP parameters (p<0.02). There was a strong and significant association between parasympathetic and sympathetic modulations with hs-CRP. Conclusion: The IT program based on the VAT promoted a decrease in hs-CRP associated with improvement in cardiac autonomic modulation.

Lack of Association Between ACE Indel Polymorphism and Cardiorespiratory Fitness in Physically Active and Sedentary Young Women.

BACKGROUND: Polymorphisms at the angiotensin-converting enzyme gene (ACE), such as the indel [rs1799752] variant in intron 16, have been shown to be associated with aerobic performance of athletes and non-athletes. However, the relationship between ACE indel polymorphism and cardiorespiratory fitness has not been always demonstrated. OBJECTIVES: The relationship between ACE indel polymorphism and cardiorespiratory fitness was investigated in a sample of young Caucasian Brazilian women. PATIENTS AND METHODS: This study investigated 117 healthy women (aged 18 to 30 years) who were grouped as physically active (n = 59) or sedentary (n = 58). All subjects performed an incremental exercise test (ramp protocol) on a cycle-ergometer with 20-25 W/min increments. Blood samples were obtained for DNA extraction and to analyze metabolic and hormonal profiles. ACE indel polymorphism was determined by polymerase chain reaction (PCR) and fragment size analysis. RESULTS: The physically active group had higher values of peak oxygen uptake (VO2 peak), carbon dioxide output (VCO2), ventilation (VE) and power output than the sedentary group (P < 0.05) at the peak of the exercise test. However, heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) did not differ between groups. There was no relationship between ACE indel polymorphism and cardiorespiratory variables during the test in both the physically active and sedentary groups, even when the dominant (DD vs. D1 + 2) and recessive (2 vs. DI + DD) models of inheritance were tested. CONCLUSIONS: These results do not support the concept that the genetic variation at the ACE locus contributes to the cardiorespiratory responses at the peak of exercise test in physically active or sedentary healthy women. This indicates that other factors might mediate these responses, including the physical training level of the women.

Association of estrogen receptor alpha gene polymorphisms with autonomic modulation of heart rate in users and nonusers of oral contraceptives.

BACKGROUND: This study examined the association between estrogen receptor α gene (ESR1) polymorphisms and blood pressure (BP), heart rate (HR) and autonomic modulation of HR in a sample population. STUDY DESIGN: Two hundred thirty-two young healthy women were selected, and those using oral contraceptives (OC) were compared with nonusers (control group). Short-term HR variability (HRV) was evaluated in both the supine and sitting positions using temporal indices rMSSD [square root of the mean squared differences of successive R-R intervals (RRi) divided by the number of RRi minus one], SDNN (root mean square of differences from mean RRi, divided by the number of RRi) and frequency domain methods. Power spectral components were reported at low frequency (LF) and high frequency (HF) and as LF/HF ratio. ESR1 c.454-397T>C (rs2234693) and c.454-351A>G (rs9340799) polymorphisms were determined by polymerase chain reaction and fragment restriction analysis. RESULTS: The ESR1 T>C and A>G polymorphisms had no effect on HR, rMSSD, SDNN, LF, HF or LF/HF ratio (supine or sitting), independently of OC use. The ESR1 T-A, T-G, C-A and C-G haplotypes were not associated with HR, BP or HRV. CONCLUSIONS: ESR1 variants had no effect on the autonomic modulation of HR in young women users and nonusers of OC and may not be implicated in cardiovascular risk in young women.

Cardiopulmonary exercise testing in the early-phase of myocardial infarction.

OBJECTIVE: To evaluate and to compare the cardiorespiratory and metabolic variables at the ventilatory anaerobic threshold level (AT) and at submaximal cardiopulmonary exercise testing (CPET) in both, healthy volunteers and in patients in the early phase after acute myocardial infarction (AMI). METHOD: Twenty-six volunteers underwent a submaximal or symptom-limited cardiopulmonary exercise testing (CPET) on a cycle ergometer and were divided into AMI group (AMIG=12, 56.33±8.65 years) and healthy group (CG=14, 53.33±3.28 years). The primary outcome measures were the cardiorespiratory and metabolic variables obtained at the peak workload and at the AT of the CPET. Statistical test: independent Student's t-test, α=5%. RESULTS: The AMIG presented lower values at the AT and the peak workload of the CPET compered to the CG: power in watts (91.06±30.10 and 64.88±19.92; 154.93±34.65 and 120.40±29.60); VO2 mL.kg-1.min-1 (17.26±2.71 and 12.19±2.51; 25.39±5.73 and 19.41±5.63); VCO2 L/min-1 (1.43±0.31 and 0.93±0.23; 2.07±0.43 and 1.42±0.36), VO2 L/min-1 (1.33±0.32 and 1.00±0.23; 1.97±0.39 and 1.49±0.36); VE L/min-1 (42.13±8.32 and 27.51±5.86; 63.07±20.83 and 40.82±11.96); HR (bpm) (122.96±14.02 and 103.46±13.38; 149.67±13.77 and 127.60±10.04), double product (DP) (bpm.mmHg.min-1) (21835.86±3245.93 and 17333.25±2716.51; 27302.33±3053.08 and 21864.00±2051.48), respectively. The variable oxygen uptake efficiency slope (OUES L/min) was lower in the AMIG (1.79±0.51) than the CG (2.26±0.37). The AMIG presented neither ECG alterations nor symptoms that limited the CPET. CONCLUSION: The results suggest that patients with AMI Killip class I presented lower functional capacity and DP compared to the CG without presenting ischemic alterations. Thus, the study suggests that submaximal CPET can be applied at an early stage to evaluate cardiorespiratory status since it is both safe and highly sensitive to detect changes.

Cardiopulmonary exercise testing in the early-phase of myocardial infarction / Teste de exercício cardiopulmonar na fase precoce do infarto do miocárdio

OBJECTIVE: To evaluate and to compare the cardiorespiratory and metabolic variables at the ventilatory anaerobic threshold level (AT) and at submaximal cardiopulmonary exercise testing (CPET) in both, healthy volunteers and in patients in the early phase after acute myocardial infarction (AMI). METHOD: Twenty-six volunteers underwent a submaximal or symptom-limited cardiopulmonary exercise testing (CPET) on a cycle ergometer and were divided into AMI group (AMIG=12, 56.33±8.65 years) and healthy group (CG=14, 53.33±3.28 years). The primary outcome measures were the cardiorespiratory and metabolic variables obtained at the peak workload and at the AT of the CPET. Statistical test: independent Student's t-test, α=5%. RESULTS: The AMIG presented lower values at the AT and the peak workload of the CPET compered to the CG: power in watts (91.06±30.10 and 64.88±19.92; 154.93±34.65 and 120.40±29.60); VO2 mL.kg-1.min-1 (17.26±2.71 and 12.19±2.51; 25.39±5.73 and 19.41±5.63); VCO2 L/min-1 (1.43±0.31 and 0.93±0.23; 2.07±0.43 and 1.42±0.36), VO2 L/min-1 (1.33±0.32 and 1.00±0.23; 1.97±0.39 and 1.49±0.36); VE L/min-1 (42.13±8.32 and 27.51±5.86; 63.07±20.83 and 40.82±11.96); HR (bpm) (122.96±14.02 and 103.46±13.38; 149.67±13.77 and 127.60±10.04), double product (DP) (bpm.mmHg.min-1) (21835.86±3245.93 and 17333.25±2716.51; 27302.33±3053.08 and 21864.00±2051.48), respectively. The variable oxygen uptake efficiency slope (OUES L/min) was lower in the AMIG (1.79±0.51) than the CG (2.26±0.37). The AMIG presented neither ECG alterations nor symptoms that limited the CPET. CONCLUSION: The results suggest that patients with AMI Killip class I presented lower functional capacity and DP compared to the CG without presenting ischemic alterations. Thus, the study suggests that submaximal CPET can be applied at an early stage to evaluate cardiorespiratory status since it is both safe and highly sensitive to detect changes.

OBJETIVO: Avaliar e comparar as variáveis cardiorrespiratórias e metabólicas no nível do limiar de anaerobiose ventilatório (LAV) e no pico do teste de exercício cardiopulmonar (TECP) submáximo em voluntários saudáveis e em pacientes na fase precoce após o infarto agudo do miocárdio (IAM). MÉTODO: Vinte e seis voluntários realizaram TECP submáximo ou sintoma limitante em cicloergômetro e foram divididos em grupo IAM (G-IAM=12, 56,33±8,65 anos) e grupo saudável (GC=14, 53,33±3,28 anos). As medidas dos desfechos principais foram as variáveis cardiorrespiratórias e metabólicas obtidas no pico e no LAV do TECP. Teste estatístico: t-Student não pareado, α=5%. RESULTADOS: O G-IAM apresentou menores valores no LAV e no pico do TECP que o GC (p<0,05): potência em Watts (91,06±30,10 e 64,88±19,92; 154,93±34,65 e 120,40±29,60); VO2mL.kg-1.min-1 (17,26±2,71 e 12,19±2,51; 25,39±5,73 e 19,41±5,63); VCO2L/min-1 (1,43±0,31 e 0,93±0,23; 2,07±0,43 e 1,42±0,36), VO2L/min-1 (1,33±0,32 e 1,00±0,23; 1,97±0,39 e 1,49±0,36); VEL/min-1 (42,13±8,32 e 27,51±5,86; 63,07±20,83 e 40,82±11,96); FC (bpm) (122,96±14,02 e 103,46±13,38; 149,67±13,77 e 127,60±10,04); duplo produto (DP) (bpm.mmHg.min-1) (21835,86±3245,93 e 17333,25±2716,51; 27302,33±3053,08 e 21864,00±2051,48), respectivamente. A variável Oxygen Uptake Efficiency Slope (OUES L/min) do G-IAM foi 1,79±0,51 e do GC 2,26±0,37, p<0.05. O G-IAM não apresentou alterações eletrocardiográficas ou sintomas que limitassem o TECP. CONCLUSÃO: Os resultados mostram que os pacientes com IAM Killip I apresentaram menor capacidade funcional e DP em relação ao GC, sem apresentar alterações isquêmicas. Assim, o estudo sugere que o TECP submáximo pode ser aplicado precocemente para a avaliação cardiorrespiratória por apresentar alta sensibilidade para detectar alterações de forma segura.

The relationship between cardiac autonomic function and clinical and angiographic characteristics in patients with coronary artery disease / Relação entre a modulação autonômica cardíaca e as características clínicas e angiográficas de pacientes com doença arterial coronariana

BACKGROUND: A reduction in heart rate variability (HRV) is considered an important indicator of autonomic dysfunction. OBJECTIVES: The aims of this study were to evaluate the presence of autonomic dysfunction measured by HRV in patients with coronary artery disease (CAD) and to compare them with normal subjects. METHODS: A sample of 52 men (mean age 54±5.39 years) was allocated into three groups: obstructive CAD ≥50 percent (CAD+ n=18), obstructive CAD <50 percent, (CAD- n=17) and apparently healthy controls (CG n=17). Heart rate (HR) was measured at rest using a Polar®S810i for 15 min. HRV was analyzed via Shannon entropy (SE) and symbolic analysis (0V and 2ULV), which relate to sympathetic and vagal predominance, respectively. Statistical analysis included the Kruskal-Wallis test and multivariate analysis (p<0.05). RESULTS: The CAD+ group presented lower SE and 2ULV percent values and higher 0V percent compared to CAD- and control groups (p<0.05). In the multivariate analysis, the presence of the clinical characteristics such as myocardial infarction and revascularization in the CAD+ group lead to a lower SE and higher 0V compared to the CAD- group. The use of angiotensin converting enzymes led to a higher SE in the CAD- group compared to the CAD+ (p<0.05). CONCLUSION: In uncomplicated CAD+ patients the patterns of HRV have a lower complexity, a greater sympathetic modulation and a lower parasympathetic modulation compared to CAD- and control groups in supine resting conditions. These results indicate that autonomic heart dysfunction is related to the degree of coronary occlusion and cardiac compromise.

CONTEXTUALIZAÇÃO: A redução da variabilidade da frequência cardíaca (VFC) é considerada como um importante marcador de disfunção autonômica. OBJETIVOS: Avaliar a VFC em pacientes com doença arterial coronariana (DAC) e compará-los com sujeitos saudáveis. MÉTODOS: Cinquenta e dois homens (53±7,2 anos), divididos em três grupos, sendo dois grupos com obstrução coronariana (DAC+ com obstrução ≥50 por cento, n=17 e DAC+ com obstrução ≥50 por cento, n=18) e um grupo controle (GC, n=17). A frequência cardíaca (FC) foi captada batimento a batimento, a partir do Polar®S810i, em repouso supino, durante 15 minutos. A análise da VFC foi feita pelos cálculos da entropia de Shannon (ES) e pelos padrões da análise simbólica (0V e 2ULV por cento), relacionados à predominância simpática e vagal, respectivamente. A análise estatística incluiu o teste de Kruskal-Wallis e a análise multivariada (p<0,05) RESULTADOS:O grupo DAC+ apresentou menores valores de ES e 2ULV por cento e maior 0V quando comparado aos grupos DAC- e CG. Na análise multivariada, observou-se menor ES e maior 0V na presença das características clínicas prévias, como infarto e revascularização do miocárdio no grupo DAC+ comparado ao grupo DAC-. O uso de inibidores da enzima conversora de angiotensina contribuiu para maior ES do grupo DAC- comparado ao DAC+. CONCLUSÃO: Na DAC+ não complicada, os padrões da VFC apresentam menor complexidade, maior modulação autonômica simpática e menor modulação parassimpática comparativamente ao DAC- e ao GC em repouso supino. Esses resultados indicam que a disfunção autonômica cardíaca está relacionada ao grau de oclusão coronariana e ao comprometimento cardíaco.

The relationship between cardiac autonomic function and clinical and angiographic characteristics in patients with coronary artery disease.

BACKGROUND: A reduction in heart rate variability (HRV) is considered an important indicator of autonomic dysfunction. OBJECTIVES: The aims of this study were to evaluate the presence of autonomic dysfunction measured by HRV in patients with coronary artery disease (CAD) and to compare them with normal subjects. METHODS: A sample of 52 men (mean age 54±5.39 years) was allocated into three groups: obstructive CAD ≥50% (CAD+ n=18), obstructive CAD <50%, (CAD- n=17) and apparently healthy controls (CG n=17). Heart rate (HR) was measured at rest using a Polar®S810i for 15 min. HRV was analyzed via Shannon entropy (SE) and symbolic analysis (0V and 2ULV), which relate to sympathetic and vagal predominance, respectively. Statistical analysis included the Kruskal-Wallis test and multivariate analysis (p<0.05). RESULTS: The CAD+ group presented lower SE and 2ULV% values and higher 0V% compared to CAD- and control groups (p<0.05). In the multivariate analysis, the presence of the clinical characteristics such as myocardial infarction and revascularization in the CAD+ group lead to a lower SE and higher 0V compared to the CAD- group. The use of angiotensin converting enzymes led to a higher SE in the CAD- group compared to the CAD+ (p<0.05). CONCLUSION: In uncomplicated CAD+ patients the patterns of HRV have a lower complexity, a greater sympathetic modulation and a lower parasympathetic modulation compared to CAD- and control groups in supine resting conditions. These results indicate that autonomic heart dysfunction is related to the degree of coronary occlusion and cardiac compromise.