Toshiki Ohta

How much exercise is required to reduce blood pressure in essential hypertensives: a dose–response study

BACKGROUND Regular aerobic exercise is widely recommended for essential hypertensives. However, it is not clear how much exercise is needed to reduce blood pressure (BP). METHODS The dose-response relation of exercise training and BP was determined using an 8-week exercise intervention study involving 207 untreated subjects with stage 1 or 2 essential hypertension. Subjects were divided into five groups based on the duration and frequency/week of exercise (sedentary control, 30 to 60 min/wk, 61 to 90 min/wk, 91 to 120 min/wk, and >120 min/wk). Age, gender, height, body mass, body mass index, dietary intake, and baseline BP were not different among the groups. RESULTS Both systolic and diastolic BP at rest did not change in the nonexercising control group. All four exercise groups demonstrated significant reductions in both systolic and diastolic BP at rest. The magnitude of reductions in systolic BP was greater in the 61 to 90 min/wk group compared with the 30 to 60 min/wk group. There were no greater reductions in systolic BP with further increases in exercise volume. The magnitude of reductions in diastolic BP was not significantly different among four exercise groups. There were no obvious relations between exercise frequency per week and the magnitude of BP decreases with exercise training. CONCLUSIONS In previously sedentary hypertensive subjects, clinically significant decreases in BP can be achieved with relatively modest increases in physical activity above sedentary levels and that the volume of exercise required to reduce BP may be relatively small that should be reasonably attainable by a sedentary hypertensive population.

A practical microcomputer-based mapping system for body surface, precordium, and epicardium☆

Abstract A practical microcomputer-based mapping system is introduced for three different potential mapping applications: (1) an array of 48 AgAgCl electrodes for epicardial mapping, (2) a system of 64 AgAgCl dry electrode for precordial mapping, and (3) an 87-electrode configuration for general body surface potential mapping. The compact, mobile microcomputer system with multiplexing and sample-and-hold techniques makes it possible to construct high-resolution maps from simultaneously sampled ECG potential data in clinical and experimental conditions. It takes only 20–25 min from the beginning of electrode placement to the completion of potential or isochronic map displays on the graphic terminal. Digital magnetic cassette tapes are used as external storage mediums which permit interchange of stored data on a larger computer.

Correlation between body surface isopotential maps and left ventriculograms in patients with old inferoposterior myocardial infarction

In 24 patients with old inferoposterior myocardial infarction, body surface isopotential maps were compared with left ventriculographic findings. In 16 patients with asynergy restricted to the inferior and/or posterolateral segment, surface potential abnormalities due to infarction were observed during specific phases of QRS and in specific portions on the chest surface depending on the location and extent of ventricular severe asynergy (akinesis and dyskinesis). However, the remaining eight patients with coexisting severe asynergy in the anterior, apical, or septal segment showed surface potential maps quite different from those of the former patients. It is suggested that body surface isopotential maps are a useful clinical tool for detecting the location and extent of ventricular severe asynergy in patients with old inferoposterior myocardial infarction.

Oxygen Uptake and Its Relation to Physical Activity and Other Coronary Risk Factors in Asymptomatic Middle-Aged Japanese

PURPOSE Low physical activity is considered to be an important risk factor for atherosclerotic coronary artery disease. However, few data are reported on the Japanese general population. The authors have studied whether oxygen uptake in physical fitness evaluation is a quantitative index for physical activity and whether or not it has a relation to coronary risk factors. METHODS Five hundred thirteen asymptomatic Japanese (40-64 years of age, 282 males and 231 females) were tested on a cycle ergometer for measurement of peak oxygen uptake (peak VO2) and oxygen uptake at anaerobic threshold (VO2AT). Physical activity was estimated by pedometer score. Data for oxygen uptake were adjusted by age or by age and body mass index (BMI), then its relationship to the following risk factors was investigated: physical activity, BMI, blood pressure, total cholesterol, HDL and LDL cholesterol, fasting blood glucose, and triglycerides. RESULTS Subjects in the highest peak VO2 quartile walked significantly more than those in the lowest quartile in both males and females. Those in the highest quartile showed lower BMI, lower blood pressure, lower triglyceride, and higher HDL cholesterol. The same relationship was observed for VO2AT. CONCLUSIONS Higher fitness level determined by peak VO2 or VO2AT is related to higher physical activity and lower coronary risk factors in the asymptomatic middle-aged Japanese. These data provide support for exercise prescription in the primary prevention of coronary heart disease in Japan.

Body Surface Isopotential Maps in Old Anterior Myocardial Infarction Undetectable by 12 Lead Electrocardiograms

Body surface isopotential maps were recorded in 30 normal subjects and 32 patients with clinical evidence of old anterior myocardial infarction but without ECG findings of infarction. Position of the minimum in maps was compared at 5 msec intervals from the onset of QRS between the normal and infarction groups. A significant difference in the mean position of the minimum was observed at 5, 10, 15, 20, and 25 msec (p less than 0.001). The minima for the two groups achieved their clearest separation at 15 msec. Twenty-six of the 32 infarction patients showed the minima on the anterior chest, but 29 of the 30 normal subjects showed the minima on the back. These findings suggest the highly specific usefulness of body surface maps for the diagnosis of the presence of old anterior infarction undetectable by 12-lead ECGs.

Walking duration and habitual exercise related to bone mineral density using computer-assisted X-ray densitometry in Japanese women

Background:  We conducted a survey to examine the difference in metacarpal bone mineral density (BMD) associated with the duration of walking and participation in habitual exercise in order to assess the benefits of walking for the prevention of bone loss in Japanese women.

Beneficial effect of physical activity on blood pressure and blood glucose among Japanese male workers

AIMS To examine the appropriate type and frequency of physical activity for the beneficial effect on hypertension and hyperglycemia. METHODS The incidence of hypertension and hyperglycemia was assessed using the results of annual physical checkups over 4 years for 5843 male employees aged 18-57 years old. Associations of different types of physical activity with the incidence of these two risk factors were examined with Cox proportional-hazard models. RESULTS There was a progressive reduction in the hazards ratios of hypertension with increasing total daily activity (hazards ratio of 0.65 (95% CI, 0.45-0.93) in subjects who walked >8000 steps/day vs. <4000 steps/day). Subjects who exercised >3 times/week also showed a significantly lower risk (0.35; 0.13-0.96) of developing hypertension vs. those who exercised <3 times/week. The only physical activity factor associated with a lower incidence of hyperglycemia was weekend (Saturday and Sunday) physical activity (0.66; 0.43-0.99, very active vs. sedentary on weekends). CONCLUSION Increasing daily and leisure time physical activities had a beneficial effect on hypertension independent from physical activity at weekend, while only doing physical activity on weekends affects an elevation of blood glucose independent of daily and leisure time physical activity.

Changes in metacarpal bone mineral density with age and menopause using computed X-ray densitometry in Japanese women: Cross-sectional and longitudinal study

Background: Bone mineral density (BMD) loss with age and menopause is widely accepted in elderly women. However, only a few studies have utilized a multiple regression model that includes physical characteristics to assess comprehensive lifetime changes in BMD. Objective: A prospective study was conducted to characterize the normal patterns in metacarpal BMD changes in Japanese women, and to assess the applicability of a fitting model using cross-sectional data compared with longitudinal variability. Subjects and methods: The study consisted of 5422 healthy women in cross-sectional data and a 1-year follow-up of 359 women. The metacarpal BMD was measured by computed X-ray densitometry. Multiple linear and nonlinear regression analyses were performed in cross-sectional subjects. Nonparametric analysis was used to compare percentage rates of BMD changes between actual and estimated values. Results: The cross-sectional data showed that the best-fit equation was a nonlinear change model using the variables of age and height in premenopausal women, and years since menopause (YSM), age and height in postmenopausal women. The results of longitudinal data indicated the following. In premenopausal women, the actual BMD changes were greater in the 30–39 age group than the 20–29 age group and were less in the 50–59 group than the 40–49 group. The rates of annual change in BMD between the actual value and estimated value by change model were very similar. In postmenopausal women, the actual changes in BMD indicated that the rapid rate of reduction observed was over 3% at 0–5 YSM and 1.5% at 6–10 YSM, and thereafter showed a slower rate of decline at 11 YSM. The change model represented the trend of actual change in BMD for postmenopausal women, whereas the rates of estimated BMD loss underestimated the actual changes at 1–10 YSM. Conclusion: The change model for premenopausal women using cross-sectional data is beneficial in evaluating the actual metacarpal BMD variability, whereas that for postmenopausal women is insufficient in estimating the longitudinal BMD variability. Résumé. Arrière plan: On accepte communément que les femmes âgées aient connu une perte de densité minérale osseuse (DMO) avec l’âge et la ménopause, cependant seulement un petit nombre d’études ont utilisé un modèle de régression multiple, qui inclut des caractéristiques physiques afin de suivre de manière adéquate les changements de DMO au cours de la vie Objectif: Une étude prospective a été menée afin de caractériser les modalités normales du changement de la DMO métacarpienne chez les femmes japonaises et pour estimer la possibilité d’appliquer un modèle d’ajustement utilisant des données transversales comparées avec la variabilité longitudinale. Sujets et méthodes: L’étude consiste en sonnées transversales de 5422 femmes en bonne santé et d’un suivi d’un an pour 359 femmes. La DMO métacarpienne a été mesurée par densitométrie radiographique calculée par ordinateur. Des analyses de régression linéaires multiples et non linéaires, ont été effectuées sur les données transversales. Une analyse non paramétrique a été utilisée pour comparer les pourcentages de changement de DMO entre valeurs estimées et valeurs observées. Résultats: Les données transversales indiquent que la meilleure équation ajustée est un modèle non linéaire employant les variables d’âge et de stature des femmes avant la ménopause, les années depuis la ménopause (ADM) et l’âge et la stature après la ménopause. Les résultats des données longitudinales indiquent qu’avant la ménopause, le changement en DMO est plus élevé dans le groupe d’âge 30–39 ans que dans le groupe d’âge 20–29 ans et ceux-ci sont inférieurs aux valeurs de des groupes 40–49 et 50–59 ans. Les taux annuels de changement de DMO que ce soit par les valeurs mesurées ou par les valeurs estimées sont similaires. Chez les femmes ménopausées, les changements en DMO observés indiquent que le rapide taux de réduction est supérieur à 3% entre 0 et 5 ans après la ménopause, puis de 1,5% entre 6 et 10 ans après la ménopause et décline à un rythme plus lent à partir de 11 ans après la ménopause. Le modèle de changement coïncide avec les changements en DMO observés chez les femmes ménopausées, tandis que les taux de perte de DMO du modèle sous estiment les changements effectifs entre 1 et 10 ans après la ménopause. Zusammenfassung. Hintergrund: Es ist allgemein bekannt, dass bei älteren Frauen die Knochendichte (bone mineral density, BMD) im Alter und mit der Menopause abnimmt. Allerdings haben nur wenige Studien ein multiples Regressionsmodell benutzt, das körperliche Merkmale einschließt, um die komplexen Änderungen der Knochendichte im Verlauf des Lebens zu erfassen. Ziel: Es wurde eine prospektive Studie durchgeführt, um das normale Muster von Mittelhandknochendichte-Änderungen bei Japanischen Frauen zu charakterisieren und um unter vergleichender Verwendung von Quer- und Längsschnittsdaten die Anwendbarkeit eines rechnerischen Anpassungsmodells zu prüfen. Probanden und Methoden: Die Studie umfasste Querschnittsdaten von 5422 gesunden Frauen und eine Einjahres-Nachuntersuchung von 359 Frauen. Die Mittelhandknochendichte wurde radiologisch mittels Rechner-Densitometrie gemessen. Multiple lineare und nicht-lineare Regressionsanalysen wurden an den Querschnittsdaten durchgeführt. Eine nicht-parametrische Analyse wurde benutzt, um die prozentuale Veränderung der Knochendichte zwischen tatsächlich gemessenen und geschätzten Werten zu vergleichen. Ergebnisse: Die Querschnittsdaten zeigten, dass die beste rechnerische Anpassung durch ein nicht-lineares Modell unter Verwendung der Variablen Alter und Körperhöhe bei Frauen vor der Menopause erzielt wurde, und unter Verwendung der Variablen Jahren seit der Menopause (years since menopause, YSM), Alter und Körperhöhe bei Frauen nach der Menopause. Die Ergebnisse der longitudinalen Daten zeigten folgendes. Bei Frauen vor der Menopause waren die tatsächlichen Knochendichteänderungen in der Gruppe der 30–39-jährigen größer als in der Gruppe der 20–29-jährigen und geringer in der Gruppe der 50–59-jährigen als in der der 40–49-jährigen. Das prozentuale Ausmaß der jährlichen Veränderung der Knochendichte zwischen den tatsächlich gemessenen und den über das Anpassungsmodell geschätzten Werten war sehr ähnlich. Bei Frauen nach der Menopause zeigten die tatsächlich gemessenen Veränderungen der Knochendichte, dass die beobachtbare Abnahmerate der Knochendichte 0 bis 5 Jahre nach der Menopause größer als 3% war, 6 bis 10 Jahre nach der Menopause 1,5% betrug, und erst 11 Jahre nach Menopause langsamer wurde. Das rechnerische Anpassungsmodell zeigte zwar den Trend der tatsächlichen Knochendichteänderung bei Frauen nach der Menopause, unterschätzte allerdings die tatsächlichen Knochendichteänderungen in den ersten 10 Jahren nach der Menopause. Resumen. Antecedentes: La pérdida de densidad mineral ósea (BMD) con la edad y en la menopausia está ampliamente reconocida en las mujeres ancianas. Sin embargo, muy pocos estudios han utilizado un modelo de regresión múltiple que tuviera en cuenta características físicas para evaluar los cambios globales que se producen lo largo de la vida en la BMD. Objetivo: Se realizó un estudio prospectivo para caracterizar los patrones normales de cambio en la BMD de los metacarpos en mujeres japonesas y para estimar la aplicabilidad de un modelo ajustado, utilizando datos transversales comparados con la variabilidad longitudinal. Sujetos y métodos: Se obtuvieron datos transversales de 5422 mujeres sanas y se realizó un seguimiento de 359 mujeres durante 1 año. La BMD de los metacarpos se determinó mediante densitometría de rayos X computerizada. Se realizaron análisis de regresión lineal y no lineal múltiple en los sujetos de la muestra transversal. Se utilizó un análisis no paramétrico para comparar las tasas porcentuales de los cambios en la BMD entre los valores reales y los estimados. Resultados: Los datos transversales mostraron que la ecuación con el mejor ajuste era un modelo de cambio no lineal, que usaba como variables la edad y la estatura en las mujeres premenopaúsicas, y los años que habían transcurrido desde la menopausia (YSM), así como la edad y la estatura, en las mujeres postmenopaúsicas. Los resultados de los datos longitudinales indicaron lo siguiente: en las mujeres premenopaúsicas, los cambios reales en la BMD fueron mayores en el grupo de 30–39 años de edad que en el de 20–29 años, y menores en el grupo de 50–59 años que en el de 40–49. Las tasas de cambio anual de la BMD entre el valor real y el estimado por el modelo de cambio eran muy similares. En las mujeres postmenopaúsicas, los cambios reales en la BMD indicaban que la rápida tasa de reducción observada era superior al 3% a los 0–5 YSM y del 1,5% a los 6–10 YSM; posteriormente, mostraban una menor tasa de disminución a los 11 YSM. El modelo de cambio representaba la tendencia del cambio real en la BMD en las mujeres postmenopaúsicas, mientras que las tasas estimadas de pérdida de la BMD subestimaban los verdaderos cambios a los 1–10 YSM.

Body surface potential distributions in posterior ventricular pre-excitation***

Waveform of the QRS complex during ventricular pre-excitation is subject to the influence of both the site of pre-excitation and the time of pre-excitation relative to that of excitation via the normal AV path. This paper reports a case in which lead V1 of the electrocardiogram (ECG) could be altered from an R to an rS pattern by the administration of atropine sulfate. The provable mechanism was that of reduced conduction time in the normal AV path with altered time phase of normal excitation and pre-excitation. This mechanism was simulated in experiments on dogs and yielded similar findings. Body surface mapping in both the patient and the dogs provided evidence that pre-excitation could be recognized by that means with varied time phase of normal excitation and pre-excitation. It was demonstrated that the QRS complex of right sided precordial leads could be altered from an R to an rS pattern by altering the time phase of normal excitation and pre-excitation of the posterior ventricular wall. This alteration was related to the degree to which negative potentials on the anterior chest wall due to right ventricular breakthrough of normal activation developed in relation to the time of pre-excitation.

The relationship between spinal and appendicular bone mass modified by physical, historical, and lifestyle factors.

Abstract: Spinal, radial, and calcaneal bone mineral density (BMD) measured by dual-energy X-ray absorptiometry (DXA) and calcaneal bone mass measured by quantitative ultrasound densitometry (QUS) were compared in 83 healthy Japanese female volunteers. A significant and strong correlation was found within the same methods (r = 0.619 for lumbar spine and radius by DXA, r = 0.760 for lumbar spine and calcaneus by DXA, and r = 0.644 for calcaneus and radius by DXA), and within the same site (r = 0.758 for calcaneus by DXA and QUS). A lesser correlation was found when both the method and site were different (r = 0.521 for radius by DXA and calcaneus by QUS, and r = 0.583 for lumbar spine by DXA and calcaneus by QUS). Relations of spinal and appendicular bone mass were examined together with physical, historical, and lifestyle factors. Multiple correlation coefficients between bone mass at the lumbar spine and appendicular bone were 0.754 to 0.782, and all these increased after modification by physical, historical, and lifestyle factors in whichever appendicular bone. In the correlation between lumbar spine and radial BMD, past weight-bearing activity, age at menarche, family history of fractures, and body weight were chosen. Menstrual status, body weight, past weight-bearing activity, and present arm-using activity were chosen to determine the correlation between lumbar spine BMD and calcaneal bone mass by QUS. These results suggest that the incorporation of those factors improved the correlation between lumbar spine BMD and appendicular bone mass, especially in cases of lumbar spine BMD versus radial BMD or calcaneal bone mass by QUS.