RESUMEN
The treatment of hypertensive patients with losartan is very common. Despite the reduction in blood pressure, its effects on cardiac contractility and sympathetic autonomic drive are still controversial. In turn, aerobic physical training (APT) also presents an important therapeutic option, providing significant improvements in cardiovascular autonomic control, however little is known about its effects on cardiac contractility, especially when associated with losartan. Therefore, we investigated in spontaneously hypertensive rats (SHR) the effects of losartan and APT on cardiac hemodynamics and functionality, with emphasis on autonomic tonic balance and cardiac contractility. Sixty-four SHR (18 weeks old) were divided into four groups (N = 16): vehicle; vehicle submitted to APT through swimming for 12 weeks; treated with losartan (5 mg·kg-1·d-1) for 12 weeks; and treated with losartan associated with APT. The groups were submitted to cardiac morphological and functional analysis by echocardiography; double blockade of cardiac autonomic receptors with atropine and propranolol; and coronary bed reactivity and left ventricular contractility analyses by the Langendorff technique. APT improved functional parameters and autonomic balance by reducing sympathetic drive and/or increasing vagal drive. In contrast, it promoted a concentric remodeling of the left ventricle (LV). Treatment with losartan reduced sympathetic autonomic drive and cardiac morphological parameters, but there were no significant gains in cardiac functionality and contractility. When combined, the concentric remodeling of the LV to APT was abolished and gains in cardiac functionality and contractility were observed. Our findings suggest that the effects of losartan and APT are complementary and should be applied together in the treatment of hypertension. In spontaneously hypertensive rats, the combination of aerobic physical training with losartan treatment was crucial to greater blood pressure reductions and an increase in left ventricular contractility. Furthermore, losartan treatment prevented the concentric left ventricular remodeling caused by aerobic physical training.
Asunto(s)
Antihipertensivos , Hipertensión , Losartán , Contracción Miocárdica , Condicionamiento Físico Animal , Ratas Endogámicas SHR , Animales , Losartán/farmacología , Losartán/uso terapéutico , Contracción Miocárdica/efectos de los fármacos , Hipertensión/tratamiento farmacológico , Hipertensión/fisiopatología , Masculino , Condicionamiento Físico Animal/fisiología , Ratas , Antihipertensivos/farmacología , Antihipertensivos/uso terapéutico , Presión Sanguínea/efectos de los fármacosRESUMEN
Aerobic physical training reduces arterial pressure in patients with hypertension owing to integrative systemic adaptations. One of the key factors is the decrease in cardiac sympathetic influence. Thus, we hypothesized that among other causes, cardiac sympathetic influence reduction might be associated with intrinsic cardiac adaptations that provide greater efficiency. Therefore, 14 spontaneously hypertensive rats (SHR group) and 14 normotensive Wistar Kyoto rats (WKY group) were used in this study. Half of the rats in each group were trained to swim for 12 weeks. All animals underwent the following experimental protocols: double blockade of cardiac autonomic receptors with atropine and propranolol; echocardiography; and analysis of coronary bed reactivity and left ventricle contractility using the Langendorff technique. The untrained SHR group had a higher sympathetic tone, cardiac hypertrophy, and reduced ejection fraction compared with the untrained WKY group. In addition, reduced coronary bed reactivity due to increased flow, and less ventricular contractile response to dobutamine and salbutamol administration were observed. The trained SHR group showed fewer differences in echocardiographic parameters as the untrained SHR group. However, the trained SHR group showed a reduction in the cardiac sympathetic influence, greater coronary bed reactivity, and increased left intraventricular pressure. In conclusion, aerobic physical training seems to reduce cardiac sympathetic influence and increase contractile strength in SHR rats, besides the minimal effects on cardiac morphology. This reduction suggests intrinsic cardiac adaptations resulting in beneficial adjustments of coronary bed reactivity associated with greater left ventricular contraction.
RESUMEN
We investigated the effects of angiotensin-converting enzyme (ACE) inhibition and aerobic physical training on the heart of old female rats (82-wk-old) submitted to premature ovarian failure (10-wk.-old). We used different approaches: morphology and function by echocardiography, reactivity of the coronary bed and left ventricular contractibility (Langendorff Technique). Female Wistar ovariectomized (OVX) rats (n=42) were assigned to one of four groups: OVX, vehicle treated only; OVX-EM, Enalapril Maleate only (EM, 10mg·kg-1·d-1); OVX-T, aerobic trained only; and OVX-EMT, treated with Enalapril Maleate and aerobic trained. Both Enalapril Maleate treatment and aerobic training were done in the last 20weeks of the experimental protocol. When compared to the OVX group, the OVX-EM group showed lower values of wall thickness and left ventricular (LV) mass, lower values of coronary bed reactivity and reduced maximum response of LV contractility to dobutamine, while the OVX-T group showed lower values of LV wall thickness, increase in end-systolic volume, reduced maximum response of LV contractility to dobutamine, and left intraventricular pressure due to increased flow. The combination of treatments (EM and aerobic physical training) did not promote additional important effects on the parameters evaluated. Our results suggest similar beneficial effects of physical training and EM treatment on the morphology and cardiac function in old female rats submitted to premature ovarian failure. Although the causes of these benefits are still unknown, both treatments have promoted a decrease in cardiac contractility, and the reduced ß1-adrenergic sensitivity suggests that both treatments may attenuate the sympathetic effect on the heart.
Asunto(s)
Inhibidores de la Enzima Convertidora de Angiotensina/farmacología , Enalapril/farmacología , Corazón/efectos de los fármacos , Condicionamiento Físico Animal , Insuficiencia Ovárica Primaria/fisiopatología , Animales , Femenino , Corazón/fisiología , Contracción Miocárdica/efectos de los fármacos , Miocardio/patología , Ovariectomía , Insuficiencia Ovárica Primaria/patología , Ratas , Ratas Wistar , Receptores Adrenérgicos beta/fisiología , Función Ventricular IzquierdaRESUMEN
BACKGROUND: We investigated whether the treatment with enalapril maleate, combined with aerobic physical training, promotes positive effects on the autonomic balance, the morphology and the cardiac function in female rats submitted to early ovarian failure. METHODS: Thirty-five female Wistar rats, ovariectomized at 10weeks of age, were assigned into Ovariectomized rats (OVX) and Ovariectomized rats treated with enalapril maleate (OVX-EM, 10mg-1·kg-1·d-1) Each group was subdivided into sedentary and trained (aerobic swimming training for 10weeks). All animals were submitted to a) double pharmacological autonomic blockade, b) study of morphology and cardiac function by echocardiography, and c) analysis of cardiac fibrosis. RESULTS: The OVX-EM sedentary group showed a significant increase in cardiac fibrosis, relative heart weight, interventricular septum thickness and increased sympathetic participation and reduced participation of the vagal tone in the determination of the basal heart rate when compared to the OVX sedentary group. Physical training reduced cardiac fibrosis in both groups, however, with less intensity in the OVX-EM group. It also increased the absolute and relative heart weight and the end-systolic volume. Finally, the OVX-EM trained group showed higher values for left ventricular end-systolic volume and lower values for ejection fraction and shortening fraction than the sedentary OVX-EM group. CONCLUSION: Enalapril maleate exacerbated cardiac fibrosis and increased sympathetic participation in the basal heart rate determination, without significantly affecting the cardiac function. Aerobic physical training did not change the cardiac autonomic control, but reduced cardiac fibrosis and had little effect on the cardiac function.
Asunto(s)
Inhibidores de la Enzima Convertidora de Angiotensina/farmacología , Enalapril/farmacología , Cardiopatías/fisiopatología , Enfermedades del Ovario/fisiopatología , Condicionamiento Físico Animal , Animales , Modelos Animales de Enfermedad , Ecocardiografía , Terapia por Ejercicio , Femenino , Fibrosis/diagnóstico por imagen , Fibrosis/patología , Fibrosis/fisiopatología , Fibrosis/terapia , Corazón/diagnóstico por imagen , Corazón/efectos de los fármacos , Corazón/fisiopatología , Cardiopatías/diagnóstico por imagen , Cardiopatías/patología , Cardiopatías/terapia , Hemodinámica/efectos de los fármacos , Hemodinámica/fisiología , Miocardio/patología , Tamaño de los Órganos , Enfermedades del Ovario/patología , Enfermedades del Ovario/terapia , Ovariectomía , Ratas Wistar , NataciónRESUMEN
RESUMO Introdução: Tem sido observado que indivíduos acometidos por acidente vascular encefálico (AVE) apresentam, além dos danos físicos, diminuição da capacidade aeróbica e alteração da modulação autonômica da frequência cardíaca, sendo estes importantes fatores para o aparecimento de doenças cardíacas e arritmias. Objetivo: Investigar os efeitos crônicos do AVE sobre a capacidade aeróbica (VO2pico) e os índices de variabilidade da frequência cardíaca (VFC), e se existe correlação entre essas duas variáveis. Métodos: Foram avaliados 11 indivíduos do sexo masculino, com idade entre 55 e 65 anos, acometidos por lesão cerebrovascular há pelo menos seis meses, e todos com hemiparesia. Foram realizadas as seguintes avaliações: teste de capacidade aeróbica máxima; registro dos intervalos R-R e cálculo dos índices da VFC (RMSSD, pNN50, AF, BF e a razão BF/AF). Para comparação entre VO2pico previsto e obtido utilizou-se o teste t de Student não pareado. Para testar a hipótese de correlação entre os índices de VFC e o VO2pico utilizou-se o teste de correlação de Pearson. Resultados: VO2pico (mL.kg-1.min-1) previsto e obtido, respectivamente = 32,15 ± 1,87 e 16,12 ± 5,51; índices da VFC: RMSSD (ms) = 28,69 ± 26,78; pNN50 (%) = 8,76 ± 12,62; AF (u.n.) = 51,96 ± 22,4; BF (u.n.) = 48,04 ± 22,49. O VO2pico correlacionou-se negativamente com os índices RMSSD, pNN50 e AF e positivamente com o índice BF (p < 0,05). Conclusão: Na fase crônica do AVE, variabilidade da frequência cardíaca encontra-se normal e os indivíduos com menor capacidade aeróbica apresentam maior modulação parassimpática e menor simpática, provavelmente em consequência da maior exigência física nas atividades de vida diária.
ABSTRACT Introduction: It has been observed that individuals affected by stroke have, in addition to the physical damage, decreased aerobic capacity and impaired heart rate variability, which are important factors for the onset of cardiac diseases and arrhythmias. Objective: To investigate the chronic effects of stroke on aerobic capacity (VO2peak) and the indices of heart rate variability (HRV), and if there is a correlation between these two variables. Methods: Eleven male individuals aged 55 to 65 affected by cerebrovascular injury for at least six months all with hemiparesis were assessed. The following evaluations were performed: maximum aerobic capacity test, record of R-R intervals and calculation of the indices of HRV (RMSSD, pNN50, HF, LF and LF/HF ratio). For the comparison between expected and obtained VO2peak the unpaired Student's t-test was used. To test the hypothesis of correlation between HRV indices and VO2peak the Pearson correlation test was used. Results: VO2peak (mL.kg-1.min-1) expected and obtained, respectively = 32.15±1.87 and 16.12±5.51; HRV indices: RMSSD (ms) = 28.69±26.78; pNN50 (%) = 8.76±12.62; HF (n.u.) = 51.96±22.4; LF (n.u.) = 48.04±22.49. The VO2peak correlated negatively with the RMSSD, pNN50 and HF indices; and positively with LF (p<0.05). Conclusion: In the chronic phase of stroke, the heart rate variability is normal and individuals with lower aerobic capacity have higher parasympathetic modulation and lower sympathetic modulations, probably due to the higher physical demand on physical activities of daily living.
RESUMEN Introducción: Se ha observado que los individuos afectados por accidente cerebrovascular (ACV) presentan, además de los daños físicos, disminución de la capacidad aeróbica y alteración de la modulación autonómica cardiaca, que son factores importantes para la aparición de la enfermedad cardiaca y arritmias. Objetivo: Investigar los efectos crónicos del ACV sobre la capacidad aeróbica (VO2 pico) y los índices de variabilidad del ritmo cardíaco (VRC), y si existe una correlación entre estas dos variables. Métodos: Se evaluaron 11 sujetos del sexo masculino de 55 a 65 años de edad afectados por una lesión cerebrovascular durante al menos seis meses, todos con hemiparesia. Se realizaron las siguientes evaluaciones: prueba de capacidad aeróbica máxima; registro de intervalos R-R y el cálculo de los índices de VRC (RMSSD, pNN50, AF, BF y la razón BF/AF). Para la comparación entre VO2pico esperado y obtenido se utilizó la prueba de la t no pareada. Para probar la hipótesis de correlación entre los índices de VRC y VO2pico se utilizó el coeficiente de correlación de Pearson. Resultados: VO2pico (mL.kg-1.min-1) esperado y obtenido, respectivamente = 32,15 ± 1,87 y 16,12 ± 5,51; índices de VRC: RMSSD (ms) = 28,69 ± 26,78; pNN50 (%) = 8,76 ± 12,62; AF (u.n.) = 51,96 ± 22,4; BF (u.n.) = 48.04 ± 22.49. El VO2pico se correlacionó negativamente con los índices RMSSD, pNN50 y AF y positivamente con el índice BF (p < 0,05). Conclusión: En la fase crónica del ACV, la variabilidad del ritmo cardíaco es normal y las personas con menor capacidad aeróbica tienen modulación parasimpática mayor y simpática menor, probablemente como resultado de una mayor demanda física en las actividades de la vida diaria.
RESUMEN
BACKGROUND: We compared the autonomic and hemodynamic cardiovascular effects of amlodipine and enalapril treatment associated with an aerobic physical training program on spontaneously hypertensive rats. METHODS: Eighteen-week-old (nâ=â48) spontaneously hypertensive rats were assigned to one of two groups: sedentary (nâ=â24) and trained (nâ=â24) through a 10-week swimming training program. Each group was subdivided into three groups (nâ=â8): control (vehicle group), amlodipine (amlodipine group; 10âmg/kg per day) and enalapril (enalapril group; 10âmg/kg per day) (both for 10 weeks). We cannulated the femoral artery and vein of all animals for recording arterial pressure and injecting drugs, respectively. Autonomic assessment was performed by double blockade with propranolol and atropine, analysis of heart rate variability (HRV), systolic arterial pressure variability and baroflex sensitivity. RESULTS: Arterial pressure reduction was more prominent in the sedentary and trained enalapril groups. Amlodipine sedentary group presented important autonomic adjustments characterized by a predominance of vagal tone in cardiac autonomic balance, increased HRV associated with sympathetic autonomic modulation reduction and increased vagal autonomic modulation, and increased baroflex sensitivity. All findings were not potentialized by physical training. In turn, the enalapril trained group, but not its sedentary counterpart, also had vagal tone prevalence in cardiac autonomic balance, increased HRV, increased baroflex sensitivity and decreased low-frequency band in systolic arterial pressure variability. CONCLUSION: Amlodipine was more effective in promoting beneficial autonomic cardiovascular adaptations in sedentary animals. In contrast, enalapril achieved better autonomic results only when combined with aerobic physical training.
Asunto(s)
Amlodipino/farmacología , Antihipertensivos/farmacología , Sistema Nervioso Autónomo/efectos de los fármacos , Enalapril/farmacología , Condicionamiento Físico Animal/fisiología , Adaptación Fisiológica , Amlodipino/uso terapéutico , Animales , Antihipertensivos/uso terapéutico , Presión Arterial/efectos de los fármacos , Barorreflejo/efectos de los fármacos , Enalapril/uso terapéutico , Frecuencia Cardíaca/efectos de los fármacos , Hipertensión/tratamiento farmacológico , Masculino , Ratas , Ratas Endogámicas SHRRESUMEN
The aim of the present study was to determine the association between abdominal muscle strength and quality of life among older adults with lumbar osteoarthritis. A blind, cross-sectional study was conducted involving 40 older adults: 20 with lumbar osteoarthritis (12 women and 8 men, mean age of 65.90 ± 4.80 years) and 20 controls (14 women and 6 men, mean age of 67.90 ± 4.60 years). The volunteers were submitted to an abdominal muscle strength test. Quality of life was evaluated using the SF-36 questionnaire. Both abdominal muscle strength and quality of life scores were significantly lower in the group with lumbar osteoarthritis in comparison to the controls (p < 0.05). Moreover, significant and positive associations were found between abdominal muscle strength and the subscales of the SF-36 questionnaire (p < 0.05, 0.421 ≥ rs ≤ 0.694). Based on the present findings, older adults with lumbar osteoarthritis with greater abdominal muscle strength have a better quality of life.
Asunto(s)
Músculos Abdominales/fisiología , Vértebras Lumbares , Fuerza Muscular/fisiología , Osteoartritis de la Columna Vertebral/fisiopatología , Calidad de Vida , Anciano , Dolor Crónico/etiología , Dolor Crónico/psicología , Estudios Transversales , Femenino , Estado de Salud , Humanos , Relaciones Interpersonales , Masculino , Salud Mental , Persona de Mediana Edad , Osteoartritis de la Columna Vertebral/complicaciones , Osteoartritis de la Columna Vertebral/psicología , Dimensión del Dolor , Método Simple CiegoRESUMEN
Introdução: Sujeitos acometidos por acidente vascular encefálico (AVE) podem apresentar alterações na estrutura e função do coração e na modulação autonômica. Objetivo: Verificar função autonômica e cardíaca sistólica em homens após AVE, e se estas variáveis estão associadas. Métodos: Foram avaliados oito homens, com idade entre 55 e 65 anos, acometidos por lesão cerebrovascular há pelo menos seis meses e todos com hemiparesia. Foram realizadas as seguintes avaliações: 1) Ecocardiografia, para avaliar a função cardíaca sistólica. 2) Registro da frequência cardíaca (FC) e dos intervalos R-R (IRR), batimento a batimento, para avaliação do controle neural do coração. Esses dados foram analisados no domínio da frequência, por meio das análises dos seguintes componentes espectrais: alta frequência; baixa frequência e a razão BF/AF. Foi aplicado o teste de correlação de Pearson (p ≤ 0,05). Resultados: Características demográficas, antropométricas e fisiológicas: Idade = 58,62 ± 2,88 anos; IMC = 27,41 ± 5,33 kg/m2 ; BF = 61,78 ± 26,79 (un); AF = 38,23 ± 26,79 (un); BF/AF = 3,41 ± 3,38; FE = 0,65 ± 0,04. Não houve correlação estatisticamente significativa entre os índices espectrais BF e AF com fração de ejeção e a presença de fatores de risco para AVE. Conclusão: No presente estudo, a fração de ejeção do ventrículo esquerdo encontra-se normal e o controle neural do coração pode estar normal ou não, mesmo na presença de fatores de risco para o AVE. .
Introduction: Subjects affected by cerebrovascular accident (CVA) may show changes in the structure and function of the heart and autonomic modulation. Objective: To assessautonomic and cardiac systolic function in men after stroke, and whether these variables are associated. Methods: Eight men aged between 55 and 65 years were evaluated, all suffering from cerebrovascular injury and with hemiparesis for at least six months. The following evaluations were performed: 1) echocardiography to evaluate systolic cardiac function; 2) Record the heart rate (HR) and RR intervals (RRI), beat by beat, to assess neural control of the heart. These data were analyzed in the frequency domain, by means of spectral analysis of the following components: high frequency, low frequency and LF/HF ratio. The Pearson correlation test was applied (p ≤0.05). Results: Demographic. anthropometric and physiological characteristics: Age = 58.62 ± 2.88 years; BMI = 27.41 ± 5.33 kg/m2; LF = 61.78 ± 26.79 (un); HF = 38.23 ± 26.79 (un); LF/HF = 3.41 ± 3.38; EF = 0.65 ± 0.04. There was no statistically significant correlation between the spectral indices of low (LF) and high frequency (HF) with stroke volume and the presence of risk factors for CVA. Conclusion: In the present study, the stroke volume of the left ventricle is normal and the neural control of the heart may be normal or not, even in the presence of risk factors for CVA. .
Introducción: Los sujetos acometidos por accidente vascular encefálico (AVE) pueden presentar alteraciones en la estructura y función del corazón y en la modulación autonómica. Objetivo: Verificar función autonómica y cardíaca sistólica en hombres después de AVE, y si estas variables están asociadas. Métodos: Fueron evaluados ocho hombres, con edad entre 55 y 65 años, acometidos por lesión cerebrovascular desde hace por lo menos seis meses y todos con hemiparesia. Fueron realizadas las siguientes evaluaciones: 1) Ecocardiografía, para evaluar la función cardíaca sistólica. 2) Registro de la frecuencia cardíaca (FC) y de los intervalos R-R (IRR), latido a latido, para evaluación del control neural del corazón. Esos datos fueron analizados en el dominio de la frecuencia, a través del análisis de los siguientes componentes espectrales: alta frecuencia; baja frecuencia y la razón BF/AF. Fue aplicado el test de correlación de Pearson (p ≤ 0,05). Resultados: Características demográficas, antropométricas y fisiológicas: Edad = 58,62 ± 2,88 años; IMC = 27,41 ± 5,33 kg/m2; BF = 61,78 ± 26,79 (un); AF = 38,23 ± 26,79 (un); BF/AF = 3,41 ± 3,38; FE = 0,65 ± 0,04. No hubo correlación estadísticamente significativa entre los índices espectrales BF y AF con fracción de eyección y la presencia de factores de riesgo para AVE. Conclusión: En el presente estudio, la fracción de eyección del ventrículo izquierdo se encuentra normal y el control neural del corazón puede estar normal o no, aún ante la presencia de factores de riesgo para el AVE. .
RESUMEN
INTRODUÇÃO: Um dos benefícios promovidos pelo exercício físico parece ser a melhora da modulação do sistema nervoso autônomo sobre o coração. No entanto, o papel da atividade física como um fator determinante da variabilidade da frequência cardíaca (VFC) não está bem estabelecido. Desta forma, o objetivo do estudo foi verificar se há correlação entre a frequência cardíaca de repouso e a carga máxima atingida no teste de esforço físico com os índices de VFC em homens idosos. MÉTODOS: Foram estudados 18 homens idosos com idades entre 60 e 70 anos. Foram feitas as seguintes avaliações: a) teste de esforço máximo em cicloergômetro utilizando-se o protocolo de Balke para avaliação da capacidade aeróbia; b) registro da frequência cardíaca (FC) e dos intervalos R-R durante 15 minutos na condição de repouso em decúbito dorsal. Após a coleta, os dados foram analisados no domínio do tempo, calculando-se o índice RMSSD, e no domínio da frequência, calculando-se os índices de baixa frequência (BF), alta frequência (AF) e razão BF/AF. Para verificar se existe associação entre a carga máxima atingida no teste de esforço e os índices de VFC foi aplicado o teste de correlação de Pearson (p < 0,05). RESULTADOS: Características demográficas, antropométricas, fisiológicas e carga máxima atingida no teste ergométrico: idade = 63 ± 3,0 anos; IMC = 24 ± 2kg/m²; FC = 63 ± 9bpm; PAS = 123 ± 19mmHg; PAD = 83 ± 8mmHg; carga máxima = 152 ± 29 watts. Não houve correlação entre os índices de VFC com os valores de FC de repouso e carga máxima atingida no teste ergométrico (p > 0,05). CONCLUSÃO: Os índices de variabilidade da frequência cardíaca temporal e espectrais estudados não são indicadores do nível de capacidade aeróbia de homens idosos avaliados em cicloergômetro.
INTRODUCTION: One of the benefits provided by regular physical activities seems to be the improvement of cardiac autonomic nervous system modulation. However, the role of physical activity as a determinant factor of the heart rate variability (HRV) is not well-established. Therefore, the aim of this study was to verify whether there was a correlation between resting heart rate and maximum workload reached in an exercise test with HRV indices in elderly men. METHODS: A study was carried out with 18 elderly men between the ages of 60 and 70 years. The following evaluations were made: a) Maximal exercise test on a cycle ergometer using Balke treadmill protocol to evaluate the aerobic capacity; b) Heart Rate (HR) and RR Intervals (RRi) registered for 15 minutes at rest, in the supine position. After collection, data were analyzed by time domain (RMSSD index) and by the frequency domain (low (LF) and high (HF) frequency indices and LF/HF ratio). Pearson correlation test was used to verify whether there was a correlation between the maximum workload reached during the exercise test and the HRV indices (p < 0.05). RESULTS: Demographic, physiological, and anthropometric characteristics and the maximum load achieved during exercise test: Age = 63 ± 3.0 years; BMI = 24 ± 2 kg/m2; HR = 63 ± 9 bpm; SBP = 123 ± 19 mmHg; DBP = 83 ± 8 mmHg; maximum workload = 152 ± 29 watts. No correlation was found between the HRV indices with the values of the resting heart rate and the maximum workload reached in the exercise test (p > 0.05). CONCLUSION: Temporal and spectral indices of heart rate variability are not indicators of aerobic capacity of elderly men evaluated on a cycle ergometer.