Kojiro Ishii

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.

Effects of static stretching for 30 seconds and dynamic stretching on leg extension power.

The purposes of this study were to clarify the effects of static stretching for 30 seconds and dynamic stretching on leg extension power. Eleven healthy male students took part in this study. Each subject performed static stretching and dynamic stretching on the 5 muscle groups in the lower limbs and nonstretching on separate days. Leg extension power was measured before and after the static stretching, dynamic stretching, and nonstretching. No significant difference was found between leg extension power after static stretching (1788.5 ± 85.7 W) and that after nonstretching (1784.8 ± 108.4 W). On the other hand, leg extension power after dynamic stretching (2022.3 ± 121.0 W) was significantly (p < 0.01) greater than that after nonstretching. These results suggest that static stretching for 30 seconds neither improves nor reduces muscular performance and that dynamic stretching enhances muscular performance.

Acute effect of static stretching on power output during concentric dynamic constant external resistance leg extension.

The purpose of the present study was to clarify the acute effect of dynamic stretching exercise on muscular performance during concentric dynamic constant external resistance (DCER, formally called isotonic) muscle actions under various loads. Concentric DCER leg extension power outputs were measured in 12 healthy male students after 2 types of pretreatment. The pre- treatments were: (a) dynamic stretching treatment including 2 types of dynamic stretching exercises of leg extensors and the other 2 types of dynamic stretching exercises simulating the leg extension motion (2 sets of 15 times each with 30-second rest periods between sets; total duration: about 8 minutes), and (b) nonstretching treatment by resting for 8 minutes in a sitting position. Loads during measurement of the power output were set to 5, 30, and 60% of the maximum voluntary contractile (MVC) torque with isometric leg extension in each subject. The power output after the dynamic stretching treatment was significantly (p < 0.05) greater than that after the nonstretching treatment under each load (5% MVC: 468.4 ± 102.6 W vs. 430.1 ± 73.0 W; 30% MVC: 520.4 ± 108.5 W vs. 491.0 ± 93.0 W; 60% MVC: 487.1 ± 100.6 W vs. 450.8 ± 83.7 W). The present study demonstrated that dynamic stretching routines, such as dynamic stretching exercise of target muscle groups and dynamic stretching exercise simulating the actual motion pattern, significantly improve power output with concentric DCER muscle actions under various loads. These results suggested that dynamic stretching routines in warm-up protocols enhance power performance because common power activities are carried out by DCER muscle actions under various loads.

Acute effects of dynamic stretching exercise on power output during concentric dynamic constant external resistance leg extension.

The purpose of the present study was to clarify the acute effect of dynamic stretching exercise on muscular performance during concentric dynamic constant external resistance (DCER, formally called isotonic) muscle actions under various loads. Concentric DCER leg extension power outputs were measured in 12 healthy male students after 2 types of pretreatment. The pretreatments were: (a) dynamic stretching treatment including 2 types of dynamic stretching exercises of leg extensors and the other 2 types of dynamic stretching exercises simulating the leg extension motion (2 sets of 15 times each with 30-second rest periods between sets; total duration: about 8 minutes), and (b) nonstretching treatment by resting for 8 minutes in a sitting position. Loads during measurement of the power output were set to 5, 30, and 60% of the maximum voluntary contractile (MVC) torque with isometric leg extension in each subject. The power output after the dynamic stretching treatment was significantly (p < 0.05) greater than that after the nonstretching treatment under each load (5% MVC: 468.4 +/- 102.6 W vs. 430.1 +/- 73.0 W; 30% MVC: 520.4 +/- 108.5 W vs. 491.0 +/- 93.0 W; 60% MVC: 487.1 +/- 100.6 W vs. 450.8 +/- 83.7 W). The present study demonstrated that dynamic stretching routines, such as dynamic stretching exercise of target muscle groups and dynamic stretching exercise simulating the actual motion pattern, significantly improve power output with concentric DCER muscle actions under various loads. These results suggested that dynamic stretching routines in warm-up protocols enhance power performance because common power activities are carried out by DCER muscle actions under various loads.

Comparison of interdevice measurement difference of pedometers in younger and older adults

Objectives In this study, the relationship between inter-instrument differences in regard to the daily number of steps with the intensity distribution of daily physical activity in younger and older adults was examined. Methods 17 younger individuals and 28 older individuals wore two pedometers (Lifecorder (LC) and EC-200 (YM)) simultaneously for 7 days, in order to determine the number of steps each took. Furthermore, LC determined the time spent in light, moderate and vigorous physical activity, corresponding to <3 metabolic equivalent (METs), 3 to 6 METs and >6 METs, respectively. Results The LC detected a significantly larger number of steps than YM (p<0.001), yet there was a strong relationship between the two measurements (r = 0.962, p<0.001). The interdevice difference with the number of steps significantly decreased in inactive older individuals compared with the active older and younger individuals, and it was also significantly negatively correlated with the time spent in light-intensity physical activity (LPA) (r = 0.523, p<0.01). Conclusion This study showed that the interdevice difference with the number of steps significantly increased in older participants due to the greater length of time spent in LPAs.

Minor effects of green tea catechin supplementation on cardiovascular risk markers in active older people: a randomized controlled trial.

Aim:  Although previous studies have shown that consumption of green tea catechins (GTC) and walking might prevent development of cardiovascular disease (CVD), the effects of GTC supplementation on CVD risk in active older people are unknown.

Accumulation of short bouts of non-exercise daily physical activity is associated with lower visceral fat in Japanese female adults.

The purpose of the present investigation was to assess the relationship between bouts of very short daily physical activity (PA) lasting <10 min with obesity and abnormal fat distributions. A total of 42 females (age 50±6 years, height 156±5 cm, body weight 54±8 kg, body mass index 22±3 kg/m2) participated in the present investigation. Computed tomography was used to evaluate the area of visceral adipose tissue and subcutaneous adipose tissue (VAT and SAT). All participants wore a pedometer with a one-axial accelerometer (Lifecorder, Kenz, Japan) in order to determine their frequency (bouts/day) of PA and moderate to vigorous intensity PA (MVPA). The total frequency of PA and MVPA, including all bout durations, was not significantly associated with the body fat distribution. The frequency of PA lasting longer than 3 min and 5 min, and MVPA lasting longer than 1 min and 3 min were significantly associated with the area of the VAT (p<0.05). A smaller area of VAT was associated with a higher frequency of PA and MVPA lasting 1-5 min. The present investigation did not find that very short bouts of PA lasting<1 min played a significant role in controlling abdominal fat distribution.

Attenuated aerobic exercise capacity in CD36 deficiency

Background: An important role of CD36 in muscle fatty acid (FA) uptake has been shown in CD36-knockout or CD36-overexpressed mice. FA is a predominant substrate in energy production during light exercise below the anaerobic threshold (AT). We studied whether aerobic exercise capacity in humans could be affected by CD36 deficiency. Methods: We investigated the ventilatory threshold (VT) and serum FA changes in normal participants (n = 22) and participants with CD36 deficiency (n = 12) during pedalling on a cycle ergometer. Results: In participants with CD36 deficiency, FA levels were not reduced at peak work rate, whereas FA levels decreased by about 50% in normal participants. Participants with CD36 deficiency showed significantly lower VT than normal participants. A significant correlation was observed between VT and percentage changes in FA at peak work rate. Conclusion: This study found reduced FA utilisation and an attenuated aerobic exercise capacity in CD36 deficiency, indicating that CD36-mediated FA oxidation is an important determinant for aerobic exercise capacity in humans.

Ultrasound-Derived Abdominal Muscle Thickness Better Detects Metabolic Syndrome Risk in Obese Patients than Skeletal Muscle Index Measured by Dual-Energy X-Ray Absorptiometry.

Sarcopenia has never been diagnosed based on site-specific muscle loss, and little is known about the relationship between site-specific muscle loss and metabolic syndrome (MetS) risk factors. To this end, this cross-sectional study aimed to investigate the relationship between site-specific muscle size and MetS risk factors. Subjects were 38 obese men and women aged 40–82 years. Total body fat and lean body mass were assessed by whole-body dual-energy X-ray absorptiometry (DXA) scan. Muscle thickness (MTH) was measured using B-mode ultrasound scanning in six body regions. Subjects were classified into general obesity (GO) and sarcopenic obesity (SO) groups using the threshold values of one standard deviation below the sex-specific means of either MTH or skeletal muscle index (SMI) measured by DXA. MetS risk score was acquired by standardizing and summing the following continuously distributed variables: visceral fat area, mean blood pressure, HbA1c, and serum triglyceride / high density lipoprotein cholesterol, to obtain the Z-score. Multiple regression analysis revealed that the MetS risk score was independently associated with abdominal MTH in all subjects, but not with MTH in other muscle regions, including the thigh. Although HbA1c and the number of MetS risk factors in the SO group were significantly higher than those in the GO group, there were no significant differences between GO and SO groups as defined by SMI. Ultrasound-derived abdominal MTH would allow a better assessment of sarcopenia in obese patients and can be used as an alternative to the conventionally-used SMI measured by DXA.

Effects of a year-long pedometer-based walking program on cardiovascular disease risk factors in active older people.

We assessed the relationship between the number of daily steps and changes in cardiovascular disease (CVD) risk factors in a year-long pedometer-based walking program for physically active older people. A total of 36 physically active older people (68.3 ± 5.8 years) completed this 59-week program. The CVD risk parameters were measured at baseline and at weeks 21 and 59. The mean number of steps increased by week 21 and was maintained at week 59 (approximately 10 000 steps, increase in 1500 steps from the baseline; P < .05). Following a significant reduction in body mass index at week 21, systolic blood pressure levels were significantly reduced, and high-density lipoprotein cholesterol levels were significantly increased at week 59 (P < .05). In summary, even active older people can achieve further protection against CVD risks by minor, but sustained, physical activity using pedometers for a period of more than 1 year.