Akira Kiyonaga

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)

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.

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.

Maximum tolerable dose of red pepper decreases fat intake independently of spicy sensation in the mouth

Dietary red pepper suppresses energy intake and modifies macronutrient intake. We have investigated whether a stimulus in the mouth and the sensation of spiciness are necessary for red pepper-induced changes in energy and macronutrient intake in human volunteers. In a preliminary test, sixteen Japanese male volunteers tasted samples of a soup with graded doses of red pepper in order to define a moderate and a maximum tolerable (strong) dose of red pepper. On the day of the experiment, a standardised breakfast was given to the volunteers. At lunchtime, the subjects ingested one of four experimental soups containing either a placebo, a moderate or a strong dose of red pepper plus placebo capsules, or a placebo soup plus capsules delivering a strong dose of red pepper. The rest of the meal was given ad libitum to all subjects. The amount of food, protein and carbohydrate ingested was similar for all conditions. Energy and fat intake were similar after the ingestion of the moderate soup compared with placebo. However, the strong soup significantly lowered fat intake compared with placebo (P=0.043), and ingestion of strong capsules also tended to suppress it (P=0.080). Moreover, energy intake after strong soup and capsules tended to be lower than placebo (P=0.089 and 0.076, respectively). The present results indicate that the maximum tolerable dose is necessary to have a suppressive effect of red pepper on fat intake. The main site of the action of red pepper is not in the mouth.

Acute creatine ingestion in human: consequences on serum creatine and creatinine concentrations.

The aim of the study was to explore the effect of an acute dose of creatine (Cr) ingestion on serum Cr and serum creatinine (Crn) concentrations. Sixteen healthy subjects ingested a single dose of Cr (20 g) followed by the measurement of serum Cr and Crn concentration for 3 h up to a maximum of 6 h (n=6). In response to Cr ingestion a large rise in serum Cr concentration was observed (by 50 folds) occurring approximately 2 1/2h after the ingestion (peak value of 2.17 +/- 0.66 mmol x l(-1)). We also found a moderate but significant rise in serum Crn concentration averaging 13 % after 3 h (peak value at 99.5 +/- 10.5 micromol x l(-1)). A dose response curve obtained in two case studies, in whom different doses of Cr were ingested (0, 2.5, 5, 10, 15, 20 g and 0, 10, 20, 30 g), showed that serum Cr concentration as well as the peak time increased linearly with Cr ingestion. In addition, acute Crn ingestion (5 g) resulted in a substantial increase in serum Crn concentration (by 10 folds) but led to a minor rise in serum Cr concentration (by 2 folds). These results suggest that when acute doses of Cr are ingested in humans, the degree of conversion of exogenous Cr to Crn in the stomach and the gut can be considered as negligible following the first 6 h of ingestion. However, further studies are required to explore the prolonged effect of Cr on Crn metabolism.

Double product response is accelerated above the blood lactate threshold

Catecholamine concentrations are known to increase sharply in the blood at work rates above the blood lactate threshold (LT); thus, we hypothesized that the double product (DP, heart rate-systolic blood pressure product) may also abruptly increase at work rates above the LT. Ninety healthy students performed a stepwise incremental test on a cycle ergometer. The slopes of the two regression lines below and above the LT for the heart rate (HR), the indirectly measured systolic blood pressure (SBP), and the DP, respectively, were compared using VO2 as an independent variable. For all three parameters the slope of the regression line above the LT was significantly higher than that below the LT. Although either the same or a lower slope was found in the HR (N = 23) or SBP (N = 22) responses in some subjects above the LT as compared with that below the LT, a steeper DP slope above the LT was evident in all 90 subjects. The same results were also obtained during 4-min constant work rate exercise sessions at a variety of submaximal intensities performed in a random order in seven subjects. In addition, we established the DP break point (DPBP) determining protocol with a fairly good test-retest reliability (r = 0.951) and a correlation coefficient between the DPBP and the LT (r = 0.900). These results suggest that the DP increases more steeply above the LT, and, as a result, the DPBP is considered to be a valid and useful parameter as a marker of the LT.

Changes in serum concentrations of taurine and other amino acids in clinical antihypertensive exercise therapy

Thirty-one Japanese with essential hypertension were divided into training (n = 21) and non-training (n = 10) groups. Physical training of 10 weeks was instituted after 4 or more weeks of observation, and changes in blood pressure and serum concentrations of taurine and other amino acids were investigated. The workload in physical training was predetermined by the submaximal multistage graded exercise test on a bicycle ergometer, and the blood lactate threshold which reflects approximately 40-60% of maximal oxygen uptake was chosen. The hypertensive patients underwent bicycle ergometer training for 60 minutes, three times a week for 10 weeks. Blood pressures were significantly decreased by 14.8/6.6 mmHg in systole/diastole in the training group, but not in the non-training group. Serum concentrations of taurine and cystine were increased significantly by 26% and 287%, in the training group. Increase in serum asparagine (11%), histidine (6%) and lysine (7%) concentrations was also significant, only in the training group. Plasma norepinephrine level and whole blood and plasma volumes were significantly reduced. The change in serum taurine level was significantly negatively correlated with the change in plasma norepinephrine. In addition there was a significant positive correlation between the change in plasma norepinephrine and the change in diastolic blood pressure in the training group. Based on these results, the increase in serum taurine which is known for its antihypertensive activity could contribute, at least in part through the reduction in plasma norepinephrine level, to the antihypertensive effect of exercise.