Munehiro Shindo

The use of uniaxial accelerometry for the assessment of physical-activity-related energy expenditure: a validation study against whole-body indirect calorimetry.

Assessing the total energy expenditure (TEE) and the levels of physical activity in free-living conditions with non-invasive techniques remains a challenge. The purpose of the present study was to investigate the accuracy of a new uniaxial accelerometer for assessing TEE and physical-activity-related energy expenditure (PAEE) over a 24 h period in a respiratory chamber, and to establish activity levels based on the accelerometry ranges corresponding to the operationally defined metabolic equivalent (MET) categories. In study 1, measurement of the 24 h energy expenditure of seventy-nine Japanese subjects (40 (SD 12) years old) was performed in a large respiratory chamber. During the measurements, the subjects wore a uniaxial accelerometer (Lifecorder; Suzuken Co. Ltd, Nagoya, Japan) on their belt. Two moderate walking exercises of 30 min each were performed on a horizontal treadmill. In study 2, ten male subjects walked at six different speeds and ran at three different speeds on a treadmill for 4 min, with the same accelerometer. O2 consumption was measured during the last minute of each stage and was expressed in MET. The measured TEE was 8447 (SD 1337) kJ/d. The accelerometer significantly underestimated TEE and PAEE (91.9 (SD 5.4) and 92.7 (SD 17.8) % chamber value respectively); however, there was a significant correlation between the two values (r 0.928 and 0.564 respectively; P<0.001). There was a strong correlation between the activity levels and the measured MET while walking (r(2) 0.93; P<0.001). Although TEE and PAEE were systematically underestimated during the 24 h period, the accelerometer assessed energy expenditure well during both the exercise period and the non-structured activities. Individual calibration factors may help to improve the accuracy of TEE estimation, but the average calibration factor for the group is probably sufficient for epidemiological research. This method is also important for assessing the diurnal profile of physical activity.

Blood pressure and hormonal responses to aerobic exercise.

Twelve patients with essential hypertension (WHO stages I-II) were subjected to mild aerobic exercise for 10 to 20 weeks. The time course of changes in the resting blood pressure and multiple hormonal responses (plasma catecholamines, prostaglandin E, renin-angiotensin system, kallikrein-bradykinin system) were monitored. Depressor response of both systolic and diastolic pressures was seen, and after 5 weeks of exercise blood pressure stabilized at a significantly lower level. Adjustment of work load in response to increased physical fitness at the 10th week produced further reduction of blood pressure especially in diastole. After exercise therapy we found significant reductions in plasma catecholamine levels, and increases in levels of plasma prostaglandin E and the urinary excretion of sodium. A reduction in systolic/diastolic (mean) pressures by more than 20/10 (13) mm Hg was seen in 50% of patients after 10 weeks and in 78% after 20 weeks of exercise. Those who achieved effective blood pressure fall after 10 weeks of training (n = 6) were compared with the rest (n = 6). This analysis revealed that the initial value of plasma renin activity of the former was significantly lower than that of the latter. Significant negative correlations (r = -0.78) also were observed between the blood pressure reduction and corresponding initial value of plasma renin activity. These results indicate that exercise therapy is a potent nonpharmacological tool for the treatment of essential hypertension, especially of the low renin type. Both diminished sympathoadrenergic activity and enhancement of prostaglandin mechanisms might be responsible for the falls in arterial pressure.

Antihypertensive and volume-depleting effects of mild exercise on essential hypertension.

After a general clinical observation period of over 4 weeks, 20 essential hypertensive subjects (Japanese) were randomly divided into two groups. One group (n = 10; 4 men and 6 women; 51.4 +/- 2.8 years of age) agreed to physical training using bicycle ergometer exercise with the intensity at blood lactate threshold for 60 minutes three times a week for 10 weeks, while the other group (n = 10; 4 men and 6 women; 51.0 +/- 2.9 years of age) did no particular physical training and was followed once a week as the control. Changes in blood pressure, hemodynamics, and humoral factors of the exercised group were compared with values in the controls. The following significant changes were found only in the exercised group. Blood pressure was significantly (p less than 0.01) reduced. Whole blood and plasma volume indices were significantly reduced (p less than 0.05, p less than 0.01, respectively). The change in ratio of serum sodium to potassium positively correlated with the change in systolic blood pressure (r = 0.76, p less than 0.02). Plasma norepinephrine concentrations both at rest and at the workload of blood lactate threshold during graded exercise tests were significantly reduced (p less than 0.05, p less than 0.02 respectively) after 10 weeks of exercise training. The change in the resting level of plasma norepinephrine positively correlated with that in the mean blood pressure. No such changes were observed in the control group. In both groups, body weight and urinary sodium excretion showed no statistically significant changes.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of low-intensity aerobic training on the high-density lipoprotein cholesterol concentration in healthy elderly subjects

The concentration of high-density lipoprotein cholesterol (HDL-C) is inversely correlated with the risk of coronary heart disease. The effects of low-intensity aerobic training on serum HDL-C and other lipoprotein concentrations were examined in healthy elderly subjects. The subjects were randomly assigned to two groups matched for sex, age, height, and weight. The training group (n = 20, 10 men and 10 women aged 67 +/- 4 years) participated in a supervised physical exercise regimen using a bicycle ergometer at an intensity of 50% estimated maximal oxygen consumption (VO2max) for 60 minutes two to four times per week for 5 months. In contrast, the control group (n = 20, 10 men and 10 women aged 68 +/- 4 years) did not perform any particular physical training. The training protocol resulted in significant increases in the VO2max (P < .05), HDL-C, HDL2-C, and HDL2-C/HDL3-C ratio (P < .01). The change in HDL2-C (r = .57, P < .01) and HDL2-C/HDL3-C (r = .63, P < .01) was positively associated with an increase in the total exercise duration per week. In addition, the total weekly exercise duration also showed a significant positive relationship with HDL-C (r = .75, P < .01), HDL2-C (r = .81, P < .01), and HDL2-C/HDL3-C (r = .71, P < .01) after the training period. The changes in body weight and the VO2max were not significantly correlated with any lipid parameters. Low-intensity aerobic training may improve the profile of HDL-C and its subfractions in healthy elderly subjects. Also, the total exercise duration may be an important factor for improving HDL-C and HDL2-C in elderly subjects.

Effect of acute exercise on plasma immunoreactive — atrial natriuretic factor☆

The effect of acute exercise on plasma immunoreactive-atrial natriuretic factor (IR-ANF) was studied in 5 healthy young males subjected to graded exercise on a bicycle ergometer at four different work intensities (approx. 30, 50, 70, and 90% VO2max respectively). Except for the final exercise period, which was continued until exhaustion, all the others were of 30 min duration. Venous blood samples were obtained in the last 2 min of each exercise period. The plasma IR-ANF response to exercise was similar to that of heart rate and systolic blood pressure in that mild exercise in the first stage (corresponding to approx. 30% VO2 max) caused a striking increase of plasma IR-ANF concentrations with a further augmentation in the next stages and a levelling off at exhaustion. Plasma arginine-vasopressin (AVP) and aldosterone (ALDO) rose significantly only in the last two stages, and the highest concentrations were observed at exhaustion. In conclusion, acute exercise stimulates ANF secretion in proportion to the intensity of exercise, while concomitant increases in plasma AVP and ALDO occur only when the work load exceeds the blood lactate (BLA) threshold.

Dietary red pepper ingestion increases carbohydrate oxidation at rest and during exercise in runners

The effects of dietary hot red pepper on energy metabolism at rest and during exercise were examined in long distance male runners 18-23 yr of age. A standardized meal was given on the evening prior to the experiment. The subjects had a meal (2720 kJ) with or without 10 g of hot red pepper for breakfast. During rest (2.5 h after meal) and exercise (pedaling for 1 h at 150 W, about 60% VO2max, using cycling ergometry), expired gasses and venous blood were collected. The meal with hot red pepper significantly elevated respiratory quotient and blood lactate levels at rest and during exercise. Oxygen consumption at rest was slightly but nonsignificantly higher in the hot red pepper meal at 30 min after the meal. Plasma epinephrine and norepinephrine levels were significantly higher in those who had only hot red pepper at 30 min after the meal. These results suggest that hot red pepper ingestion stimulates carbohydrate oxidation at rest and during exercise.

The effects of long-term low intensity aerobic training and detraining on serum lipid and lipoprotein concentrations in elderly men and women

The effects of long-term low intensity aerobic training and detraining on serum lipid and lipoprotein concentrations were examined in 30 elderly men and women. These subjects were randomly divided into two groups. The training group [n=15; 7 men and 8 women; mean age 75.5 (SD 5.6) years] agreed to take part in physical training using a treadmill with an exercise intensity at the blood lactate concentration threshold for 30 min 3–6 times a week for 9 months. The other group [n=15; 7 men and 8 women; mean age 73.7 (SD 4.4) years] did not perform any particular physical training and was followed as the control. Following this training period the high density lipoprotein-cholesterol (HDL-C) had increased significantly (P<0.01) while the total cholesterol (TC) : HDL-C ratio had decreased significantly (P<0.01) in the training group after 9 months but had not changed in the control group. The TC, triglyceride (TG) and low density lipoprotein-cholesterol (LDL-C) had not changed significantly in either group. No significant difference was seen between the groups throughout the period for TC, LDLC or TG. There was, however, a significant correlation between the initial TC:HDL-C ratio and the change in the TC:HDL-C ratio following 3 months of training (P <0.05). After 1 month of detraining in 5 patients, the HDL-C had decreased significantly (P < 0.05) while the TC:HDL-C had increased significantly in the training group (P<0.01). These results suggested that long-term low intensity aerobic training improved the profile of serum lipid and lipoprotein concentrations, while detraining returned the profile to that of the pretraining levels in elderly persons.

Blood pressure lowering effect of low intensity aerobic training in elderly hypertensive patients

PURPOSE The purpose of this investigation was to determine the effect of 9 months of low intensity aerobic training on blood pressure in elderly hypertensive patients who were receiving antihypertensive medication. METHODS The training group (N = 13; mean age 75.4 +/- 5.4 yr) agreed to take part in physical training using a treadmill with an exercise intensity at the blood lactate threshold (LT) for 30 min three to six times a week for 9 months. The rest (N = 13; mean age 73.1 +/- 4.2 yr) served as controls. RESULTS The resting systolic (-15 +/- 8 mm Hg), mean (-11 +/- 6 mm Hg), and diastolic blood pressures (-9 +/- 9 mm Hg) decreased significantly after 3 months of training and the blood pressure of all participants stabilized at a significantly lower level by the end of the study (9 months) in the training group, whereas no significant changes in blood pressure were found in the control group. Both the pretraining systolic and diastolic blood pressure of those recruited patients negatively correlated with those changes after the training (SBP: P < 0.01; DBP: P < 0.05, respectively). After 1 month of detraining in five patients, the blood pressure levels were similar to those in the pretraining state. The LT increased significantly in the training group (P < 0.01). CONCLUSION In conclusion, an additional antihypertensive effect of mild aerobic training at the LT was confirmed in elderly patients receiving antihypertensive medication. The cessation of such training in five patients, however, resulted in a relatively rapid return to pretraining levels within a month.

Long-period accelerometer monitoring shows the role of physical activity in overweight and obesity

CONTEXT:Physical activity (PA) plays an important role in obesity. A new accelerometer has been developed to assess total energy expenditure as well as PA.OBJECTIVE:To investigate the association of PA with overweight and obesity in Japanese men and women, a large cross-sectional study was performed using a single-axis accelerometer.DESIGN, SETTING AND PARTICIPANTS:Population-based cross-sectional study of Japanese 18–84 y of age. Height, body weight and PA were measured in 400 male and 388 female Japanese volunteers from 1999 to 2000. The outcome measurements were overweight and obesity, which are defined as a body mass index ≥25 kg/m2. PA was measured for 1 to 4 weeks and was then categorized into three activity levels, which were defined as light, moderate and vigorous PA.RESULTS:Prevalence of overweight and obesity was 22.3%. Number of steps and time spent in moderate and vigorous PA per day were lower in overweight and obese individuals. No difference was found in time spent in light PA. Individuals who are in the 4th and 5th quintile of moderate and vigorous PA showed a significantly lower body mass index. When odd ratios (ORs) of overweight and obesity estimated by logistic regression were used as effect measures, overweight and obesity were negatively associated with vigorous PA (ORs=0.91).CONCLUSION:These results indicate that overweight and obese individuals have a lower step rate and are spending less time for moderate to vigorous PA. Participation in vigorous PA is an important predictor of overweight and obesity.

The physical activity patterns of cardiac rehabilitation program participants.

PURPOSE This investigation aimed to examine the physical activity patterns of cardiac rehabilitation program (CRP) participants. METHODS The investigation enrolled 53 male and 24 female CRP participants between 46 and 88 years of age. By means of a uniaxial accelerometer (Life-Corder), the amount of physical activity (in kilocalories) and the time spent in physical activity at light (<3 metabolic equivalents [METs]), moderate (3 to 6 METs), and vigorous (>6 METs) intensity were evaluated. In addition to these variables, the MET levels for the CRP and non-CRP periods were calculated. RESULTS The weekly amount of physical activity energy expenditure averaged 1597 +/- 846 kcal/week, and the time spent in light, moderate, and vigorous physical activity averaged, respectively, 375.5 +/- 124.5 minutes, 125.2 +/- 109.4 minutes, and 5.7 +/- 12.8 minutes per week. These levels were significantly lower on non-CRP days than on CRP days: 177 +/- 113 versus 299 +/- 161 kcal/day and, respectively, 49.3 +/- 19.3 versus 59.7 +/- 19.8 minutes, 10.5 +/- 14.6 versus 26.4 +/- 20.4 minutes, and 0.4 +/- 1.7 versus 1.4 +/- 3.0 minutes per day. CONCLUSIONS These results indicate that the amount of physical activity was generally adequate on CRP days, but failed to reach target levels on non-CRP days. Thus CRP participants, when it is medically appropriate, should be encouraged to incorporate lifestyle physical activity, additional exercise, or both on non-CRP days to supplement their caloric expenditure from CRP exercise sessions.