Relationship of physical activity, fitness level and the short time extracurricular activities : Cross-sectional study of elementary school children / 体力科学

Recent health guidelines suggest that children should accumulate 60 minutes of physical activity (PA) of moderate to vigorous intensity every day. The purpose of this study was to assess PA on weekdays, in addition to physical fitness, in elementary school children during short-term extracurricular activities (EA). Children from an elementary school (n=160) who carried out EA were assigned to the EA group, and children from the neighboring elementary school (n=210) comprised the non-EA group. A physical fitness test was applied to evaluate physical fitness in pupils. Moreover, 48 children (EA, n=24; non-EA, n=24) wore a pedometer with a uniaxial accelerometer to determine the amount of PA and time spent in moderate- to vigorous-intensity PA. The PA of EA was evaluated with the exception of the short program (10 min). Jogging distance of the EA was 1357 ± 333 m, average speed was 170 ± 42 m/min. The estimated energy consumption of jogging was 55 ± 19 kcal. Multiple items of the physical fitness test scored significantly higher in the EA group than in non-EA subjects. Total step counts were 15485 ± 1915 steps/day for the EA group and 12363 ± 2464 steps/day for the non-EA group on weekdays (p<0.001). Time spent in moderate- to vigorous-intensity PA on weekdays was 61.6 ± 10.0 min/day for EA children and 46.5 ± 12.9 min/day for non-EA children (p<0.001). In addition, the extent of PA in the EA group was higher than the amount recommended for children in general. This study suggested that short-term EA are related to both the fitness and PA levels of elementary school children.

Allometry theory to create a standard value for bone mineral content for menstruating adult females and examination of usefulness / 体力科学

Evidence suggests that sports activity can induce site-specific changes in bone mineral content (BMC) in athletes. Therefore, the first purpose of this study was to create a standard value for BMC (SV_BMC) that is independent of body size and physical exercise effect. The second purpose was to examine usefulness for the SV_BMC. In creating the SV_BMC, we recruited non-customer subjects who engaged in regular exercise but did not have site-specific changes to their bony structure. We studied 285 females (34.0±6.5 years) that were currently active, free from hormone treatment, and were not taking medication for any condition. Furthermore, all female subjects reported having a normal menstrual cycle. Bone area (BA), BMC and areal bone mineral density (aBMD) were measured by dual-energy X-ray absorption. Measurements of almost the complete skeleton, with the exception of the head, were taken (herein referred to as sub-total). This included scans of the entire spinal column, all 12 ribs, pelvis, full legs and arms. An allometry formula that relates BMC and BA was applied to determine the SV_BMC. To exclude the effect of body size, calculations were determined using the perpendicular distance from the data of each individual to that determined by allometry regression. Finally, the mean and standard deviation of the distance were converted into T-scores. In examination of reliability for the SV_BMC, we calculated the SV_BMC for three customer females who engaged in regular exercise. We found a significantly positive relationship between SV_BMC and weight/BMI. This correlation was weaker than the relationship between SV_BMC and BMC, as expected, or the relationship between SV_BMC and aBMD, with the exception of SV_BMC in the pelvis. In conclusion, this study suggests that SV_BMC is less affected by body size than by BMC or aBMD and the SV_BMC was provided highly useful in case study.

The effect of bench-stepping exercise training on BMD, BMC and bone metabolism in menopausal women / 体力科学

Since the effect of the submaximal aerobic exercise on bone had been controversial, the aim of this study was to elucidate the effect of the bench step (BS), that seemed to deliver higher mechanical load on bone than any other aerobic exercises, on the total bone mineral content (BMC) and the bone metabolism of menopausal women. Sixteen menopausal women (65 ± 9 years old) as the exercise group (ExG) and 28 pre-menopausal women (43 ± 3 years old) as the control group (CG) were studied. ExG carried out BS training with the exercise intensity at lactate threshold (LT) for 21 weeks. In ExG, BMC was measured by dual energy X-ray absorptiometry (DXA) at one year before the intervention (A year before), pre-intervention (Pre) and post-intervention (Post). Serum osteocalcin (OC) as the marker of bone formation and serum type I collagen cross-linked N-telopeptide (NTx) as the marker of bone absorption at Pre, 11th week of the intervention and Post. In CG, BMC was measured annually without the intervention. In ExG, OC was not changed, but NTx was significantly decreased by intervention (<i>p</i><0.05). The decreased amount of annual change in BMC between a year before and Pre (T1) was significantly higher compared to that between Pre and Post (T2) (<i>p</i><0.01) and CG (<i>p</i><0.001). There was no significant difference between T2 and CG. In conclusion, BS with LT could prevent decreasing BMC in menopausal women, and maintain the same level of BMC in pre-menopausal women by suppressing the bone absorption.

Effects of slightly-weighted shoe intervention on lower limb muscle mass and gait patterns in the elderly / 体力科学

This study investigated the effects of exercise intervention with a 12-week slightly-weighted shoe on lower-limb skeletal muscle and gait patterns in the elderly. A total of 29 healthy elderly Japanese who had irregular walking habits were randomly assigned to either slightly-weighted-shoe (WS group, n = 14; Age, 70.6 ± 5.7 years; WS, 493 g) or normal-shoe (NS group, n = 15; Age, 69.3 ± 6.9 years; NS, 293 g) intervention groups. The participants were instructed to maintain their normal daily physical activity (PA) during the intervention period. Segmental intracellular water (ICW) and muscle thickness (MT) were measured as an index of skeletal muscle mass in the lower limb, and kinematic gait data were acquired by motion analysis. Walking stability was assessed as a standard deviation of the vertical fluctuation in whole-body center of mass (COM fluctuation). The daily PA was monitored using an accelerometer and an activity record. ICW in the upper leg and MT of rectus femoris increased significantly in the WS group compared with the NS group (ICW: 13.8% vs. 2.2%, MT: 12.1% vs. 1.3%), while COM fluctuation was significantly reduced in the WS group (p<0.05) during normal walking. The present study demonstrated that interventions with a slightly-weighted-shoe may be able to increase muscle volume in the upper leg and change gait patterns in the healthy elderly.

Change in heart rate at double product break point and validity of utilizing age-predicted heart rate at 50%VO₂max due to improvement of cardiovascular fitness / 体力科学

Previously, we have reported that age-predicted heart rate at 50%VO₂max (HR@50%VO₂max) is an effective index of adjusting appropriate exercise intensity for health promotion exercise. Thus, the aim of this study is to elucidate the change in HR at double product break point (HR@DPBP) and the validity of HR@50%VO₂max due to improvement of cardiovascular fitness. Ninety two healthy adults (57 +/- 9 years old), who participated in the health exercise training course, were studied. Participants were instructed how to control the intensity of physical activity for DPBP during their daily life. DPBP was determined with the use of incremental exercise test, and METs at DPBP (METs@DPBP), HR@DPBP, ratings of perceived exertion at DPBP (RPE@DPBP) were measured before and after the course. HR@50%VO₂max was calculated with the following formula; 138 - age/2 (bpm). METs@DPBP significantly increased (p<0.001) after 10 weeks of the course, whereas HR@DPBP did not change. Interestingly, however, there was a significantly positive correlation (p<0.001) between amount of change in METs@DPBP and that in HR@DPBP (ΔHR@DPBP). Multiple linear regression analysis indicated this correlation was independent from sex, age and amount of change in HR at rest (p<0.001). Before and after the course, proportion of study subjects’ %ΔHRs ((HR@50%VO₂max - HR@DPBP) / HR@DPBP x 100) within -10% ~ +10% were both 48.9%, and proportion of study subjects’ RPEs@DPBP within 11~13 were 92% and 85%, respectively. In this study, it was identified that significantly positive relation between amount of change in cardiovascular fitness and that of ΔHR@DPBP. This finding was independent from potentially affecting factors. In conclusion, this longitudinal study could suggest that HR@50%VO₂max and RPE were valuable indexes of determining exercise intensity for health promotion exercise.

THE RELATION BETWEEN DOUBLE PRODUCT BREAK POINT DURING SUB-MAXIMAL EXERCISE AND ARTERIAL STIFFNESS IN HEALTHY ADULT FEMALES / 体力科学

The purpose of this study was to elucidate the relation between double product break point (DPBP) and pulse wave velocity (PWV).Two hundred three healthy Japanese females were studied (mean age; 53.5 +/- 11.7 years old). The DPBP was measured by continuous incremental exercise test with a bicycle ergometer (ML-3600, Fukuda Electronic Co. Ltd). The work rate at DPBP was converted into metabolic equivalents (METs@DPBP). The brachial-ankle PWV (baPWV) was also measured. In addition, height, weight and mean blood pressure (mBP) were measured and physical activity condition in daily life (PA) was evaluated by questionnaire.The mean METs@DPBP was 5.0 +/- 0.7 METs. The mean baPWV was 1,373 +/- 254 cm/ sec. The relation between METs@DPBP and baPWV was investigated with the use of multiple linear regression models with adjustment for affecting factors of baPWV.In this study, it was identified that there was a significantly inverse relation between METs@DPBP and baPWV (<i>p</i> <0.01). This finding was independent from age, height, weight, mBP and PA. Thus, there was an inverse relation between sub-maximal aerobic capacity and arterial stiffness.

AN INVERSE ASSOCIATION BETWEEN PREDICTED 50%VO₂MAX PER BODY WEIGHT AND CORONARY RISK FACTORS / 体力科学

The aim of this study is to elucidate the relationship between the predicted 50%VO₂max/wt (ml/kg/min) and coronary risk factors (CRFs).Seven hundred eighty six men (37.3 +/- 13.5 years old) and 1,268 women (41.5 +/- 13.6 years old) were studied. The predicted 50%VO₂max/wt was calculated by utilizing data from the continuous incremental exercise test with a stationary bicycle ergometer and the age-predicted heart rate at 50%VO₂max (=138-age/2). As CRFs, percent body fat, systolic blood pressure, diastolic blood pressure, total cholesterol, triglyceride, high density lipoprotein cholesterol, fasting blood sugar and HbA1c were measured.The age-adjusted odds ratio of having abnormal values in CRFs across quartiles of the predicted 50%VO₂max/wt (highest to lowest) were 1.00 (reference), 1.39, 2.64, and 6.78 in men, and 1.00, 1.73, 2.33 and 3.44 in women (for trend, <i>p</i><0.001), respectively.This study indicated that the lower 50%VO₂max/wt resulted in the higher odds ratio of having abnormal values in CRFs among Japanese. It was also confirmed that the sub-maximal aerobic capacity was associated with CRFs.

COMPARISON OF HEART RATE AT DOUBLE PRODUCT BREAK POINT TO AGE-PREDICTED HEART RATE AT 50%VO₂max / 体力科学

In this study, we examined a reliability of age-predicted heart rate (HR) for the 50%VO₂max which is widely used during a training program for health promotion as compared to HR at the double product break point (DPBP). Two hundred fifty six non-hypertensive subjects (NHT), and 49 hypertensive ones under medication (HT) were studied. HT subjects were divided into two subgroups based on antihypertensive medications, ones with HR non-suppression agents (HT+HRNS) and the other with HR suppression agents (HT+HRS). DPBP was measured with the use of an incremental exercise test, and HR at DPBP (HR@DPBP) was determined. Age-predicted HR for the 50%VO₂max intensity of exercise was calculated with the following formula; HR=138–age/2. Measurable rate of DPBP and HR@DPBP in NHT, HT+HRNS and HT+HRS were 93.8% and 120±14bpm, 92.7% and 104±12bpm, 78.5% and 94±16bpm, respectively. There were significant differences in HR@DPBP and age-predicted HR in NHT and HT+HRS (<i>p</i><0.01 in both groups). But %ΔHR ((age-predicted HR–HR@DPBP)/HR@DPBP x 100) within -10%∼+10% in NHT, HT+HRNS and HT+HRS were 68%, 58% and 14%, respectively. This might be due to HR at rest with sitting position that was significantly correlated to %ΔHR in all groups (r=-0.604, <i>p</i><0.001 in NHT, r=-0.689, <i>p</i><0.001 in HT+HRNS and r=-0.761, <i>p</i><0.05 in HT+HRS, respectively). And the range of HR at rest with sitting position corresponding to -10%∼+10% of %ΔHR were 70∼95bpm in NHT, 71∼93bpm in HT+HRNS and 83∼102bpm in HT+HRS. In addition, this study indicated that DPBP could be measured even under antihypertensive medication that might affect DPBP measurement.In conclusion, we demonstrated that HR at DPBP and age-predicted HR were similar among 58-68% of NHT and HT+HRNS. And the range of HR at rest with sitting position to ensure reliability of age-predicted HR was elucidated.

RELATIONSHIP BETWEEN DOUBLE PRODUCT BREAK POINT AND ST SEGMENT DEPRESSION ON ECG IN PATIENTS WITH ISCHEMIC HEART DISEASE PATIENTS AND ELDERLY PERSONS / 体力科学

Double product (DP, heart rate × systolic blood pressure) during an incremental exercise test has been known to start to increase steeply at a workload, i. e. double product break point (DPBP), which corresponds to the blood lactate threshold. The study was to investigate the relationship between DP transition and ST segment depression in electrocardiogram during exercise. Thirty-one patients of angina pectoris of effort and 140 elderly persons performed a continuous incremental exercise test using a stationary bicycle ergometer. During the entire test, HR and blood pressure were measured every 15 seconds and an electrocardiogram was recorded continuously. DPBP was then calculated. In ten of the 31 patients, ST level depression above -0.1 mV with a typical ischemic form in lead V 5 was observed during the test. However, workload at the DPBP was significantly lower than that of the ischemic threshold on the electrocardiogram (i. e. -0.1mV of ST depression) in relation to work load (46+/-16 vs. 78+/-20 watts), HR (96+/-13 vs. 117+/-13 bpm), SBP (160+ /-20 vs. 199+/-31 mmHg) and DP (15400+/-3400 vs. 23400+/-4900 bpm × mmHg) . In elderly persons, DPBP could be determined without the ischemic ST depression in 96% of 327 tests. This study indicated that the DPBP would be an objective index of exercise intensity with lower risk for exercise prescription in cardiac patients and elderly persons.

Comparison of Daily Energy Expenditure in Young and Older Japanese Using Pedometer with Accelerometer / 体力科学

Daily energy expenditure has been measured by the physical activity recording and/or the questionnaire method. Recently, the accelerometer or pedometer is used to measure daily energy expenditure. The purpose of this study was to examine validity of the pedometer with accelerometer and to compare the daily physical activity between young and older Japanese. To examine validity of the pedometer, 10 young subjects worn the pedometer (Lifecorder) on the waist and then performed the walking test. Energy expenditure was measured by the expired gas analysis during the test. Fourtythree young and 54 older subjects worn the Lifecorder on the waist during free-living condition for 14 days. The intensity of Lifecorder had a high correlation with the physical activity intensity (METs) (r=0.958, P<0.001) . In the free-living condition, daily energy expenditure was 2171±305 kcal in young and 1617±196kcal in older (P<0.001) . Total step in young was significantly higher than older (young: 9490±2359 steps ; older: 6071±2804 steps, P<0.001) . There was no significant difference in the duration of physical activities at the Lifecorder intensity 1 such as desk working, watching TV sitting on a sofa and driving a car. However, the duration more than the intensity 2 corresponding to 2.2 METs in young subjects was longer than that in older (P<0.001) . We concluded that in older subjects, not only amounts of daily energy expenditure but also intensities of daily living were lower compared to the young subjects.

The effects of long-term low intensity aerobic training and the cessation of training on the serum lipid and lipoprotein concentrations in older patients / 体力科学

The effects of long-term low intensity aerobic training and detraining on serum lipid and lipoprotein concentrations were examined in 10 older patients suffering from hypertension and coronary heart disease. Training was carried out for 30 minutes 3-6 times a week for a mean of 17.1 months using a treadmill with the intensity level set at the blood lactate threshold (LT) .<BR>Following this training both LT and the serum HDL-c increased significantly (P<0.001, P<0.01, respectively) after 6 months while the TC/HDL-c ratio decreased singificantly (P<0.001) only after 1 month and stabilized at a steady favorable value throughout the remainder of the study. The serum TC, TG and LDL-c did not change significantly by the end of the training period. There was a significant negative correlation between the initial TC/ HDL-c level and the change in the TC/HDL-c level at 1 month after training (r=-0.71, P< 0.02) . Only 1 month after the detraining the HDL-c decreased significantly while the TC/HDL-c increased in comparison with the final training value (P<0.001, P<0.05, respectively) and then returned to the pre-training levels.<BR>In conclusion, these results suggest that long-term low intensity aerobic training could improve the profile of the serum lipid and lipoprotein concentrations in older patients. However, these results might depend on such factors as a low HDL-c level, a high TG level, the length of the exercise period, or the frequency per week and the age of the patient, while the cessation of such training quickly returned the profile to that of pre-training levels.

The effects of long-term mild aerobic training at lactate threshold and its cessation on blood pressure in older hypertensive patients under medication / 体力科学

After a general clinical observation period of 3 months, men and women from 66-82 yr. of age with hypertension (n=10) were studied to assess the effects of long-term mild aerobic training and detraining on their blood pressure. Ten patients agreed to take part in aerobic training using a treadmill with the intensity at the lactate threshold (LT) for 30minutes 3-6 times a week for mean 17.1±9.8 months while the time course of changes in the resting blood pressure was monitored.<BR>Following the training period the LT increased significantly by the end of the training period (P<0.001) . After 3months of training both the systolic and diastolic blood pressure decreased significantly (P<0.05, respectively) and both blood pressures stabilized at a significantly lower level throughout the remainder of the study. The mean blood pressure decreased significantly for 9 months (P<0.05) . Finally, the systolic, mean and diastolic blood pressure were found to have decreased significantly, by 9, 5, 11 mmHg, respectively by the end of the training period. (SBP and MBP: P<0.05, DBP: P<0.01, respectively) . One month after the training ended the systolic, mean and diastolic blood pressure all increased significantly (SBP and MBP: P<0.001, DBP: P<0.01, respectively) and approached the initial pre-training levels.<BR>In conclusion, the antihypertensive effect of mild aerobic training at the LT was confirmed for older patients taking antihypertensive medications. However, the cessation of such training resulted in a quick return to pre-training levels.

Effects of 9 months mild aerobic training on serum lipids and lipoprotein concentrations in older than 65 years men and women with hypertension / 体力科学

In the present study, we instiuted a long-term mild aerobic training program for older patients with hypertension and investigated its effects on serum lipids and lipoprotein concentrations. The intensity of exercise in mild aerobic training was adjusted to the lactate threshold level (LT), i, e., the level at which the blood lactate concentration began to increase nonlinearly with increasing work intensity. The training group (15 patients, 7 men and 8 women) and control group (15 patients, 7 men and 8 women) were 65-83 year-old patients with mean ages of 75.5±5.6 and 73.7±4.4 (mean±S.D), respectively, who had never exercised regularly up to that time. Treadmill training at the LT was carried out for 30min/day 3-6 times/week and continued for 9 months under the supervision of exercise physiology specialists.<BR>In the training group, LT speed significantly increased from 3.43±0.65 km/h to 3.73±0.67 km/h (9.0%) in men, and from 2.75±0.57 km/h to 3.05±0.61 km/h (11.8%) in women (both P<0.05) . HDL-c was significantly increased 9 months after training both in men (19.2%) and women (20.9%) (both P<0.05) . The TC/HDL-c ratio, an atherogenetic index, was significantly (P<0.05) decreased by training in women but not in men. The other serum lipid and lipoprotein profiles were unchanged in both men and women. In the control group, all serum lipid and lipoprotein profiles were unchanged in both men and women.<BR>The HDL-c level in the training group was higher than in the control group after 9 months in both men and women (both P<0.02) . The TC/HDL-c ratio in the training group was lower only in women (P<0.02) . There were no significant differences in other values between the training group and the control group in either men or women.<BR>These results suggest that mild aerobic training at the LT is an effective method of improving the level of serum HDL-c, the TC/HDL-c ratio and aerobic capacity in the older patients with hypertension.