Kazuhiro Morimura

Estimation of thigh muscle cross-sectional area by single- and multifrequency segmental bioelectrical impedance analysis in the elderly

Bioelectrical impedance analysis (BIA) has been used to estimate skeletal muscle mass, but its application in the elderly is not optimal. The accuracy of BIA may be influenced by the expansion of extracellular water (ECW) relative to muscle mass with aging. Multifrequency BIA (MFBIA) can evaluate the distribution between ECW and intracellular water (ICW), and thus may be superior to single-frequency BIA (SFBIA) to estimate muscle mass in the elderly. A total of 58 elderly participants aged 65-85 years were recruited. Muscle cross-sectional area (CSA) was obtained from computed tomography scans at the mid-thigh. Segmental SFBIA and MFBIA were measured for the upper legs. An index of the ratio of ECW and ICW was calculated using MFBIA. The correlation between muscle CSA and SFBIA was moderate (r = 0.68), but strong between muscle CSA and MFBIA (r = 0.85). ECW/ICW index was significantly and positively correlated with age (P < 0.001). SFBIA tends to significantly overestimate muscle CSA in subjects who had relative expansion of ECW in the thigh segment (P < 0.001). This trend was not observed for MFBIA (P = 0.42). Relative expansion of ECW was observed in older participants. The relative expansion of ECW affects the validity of traditional SFBIA, which is lowered when estimating muscle CSA in the elderly. By contrast, MFBIA was not affected by water distribution in thigh segments, thus rendering the validity of MFBIA for estimating thigh muscle CSA higher than SFBIA in the elderly.

Epoch length and the physical activity bout analysis: An accelerometry research issue

BackgroundThe purpose of the present investigation was to compare the bouts of daily physical activity (PA) determined by three different accelerometer epoch lengths under free-living conditions.MethodsOne hundred thirty-four adults (50 ± 7 years) wore an accelerometer (Lifecorder) for 7 consecutive days under free-living conditions in order to determine the time spent in physical activity of light intensity (LPA), moderate intensity (MPA), vigorous intensity (VPA), moderate to vigorous intensity (MVPA), and the total physical activity (TPA; sum of LPA, MPA and VPA). Additionally, all PA was divided according to the bout durations (sporadic, >3 min, >5 min, and > 10 min). These indices of PA were analyzed using three different epoch lengths (4 sec, 20 sec and 60 sec) derived from the accelerometer.ResultsThe LPA significantly increased in association with increases in the epoch length (48.7 ± 15.9 to 178.7 ± 62.6 min/day, p < 0.05). The amount of sporadic VPA determined by the shortest epoch length (2.9 ± 5.2 min/day) was significantly longer than the two remaining epoch lengths (1.1 ± 2.4 to 0.9 ± 2.5 min/day, p < 0.05). The times of the MVPA bouts lasting longer than 3 minutes determined using the 4-second epoch length (2.6 ± 5.4 to 7.7 ± 10.0 min/day) were significantly shorter than those determined using the other two settings (6.5 ± 10.5 to 13.8 ± 13.8 min/day, p < 0.05). The frequencies of the MVPA bouts lasting longer than 10 minutes determined using the 4-second epoch length (0.2 ± 0.3 bouts/day) were significantly lower than those determined using the other two settings (0.3 ± 0.4 bouts/day, p < 0.05).ConclusionThe epoch length setting of the accelerometer affects the estimation of the PA bouts under free-living conditions in middle-aged to older adults.

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.

Influence of Dietary Sodium and Potassium Intake on the Heart Rate Corrected-QT Interval in Elderly Subjects.

It is well known that imbalances in the dietary electrolytes are associated with a significantly higher incidence of cardiovascular disease (CVD). On the other hand, a prolonged heart rate corrected-QT (QTc) interval is associated with an increased risk of cardiac autonomic nervous system dysfunction, the incidence of CVD and sudden cardiac death. This study was designed to clarify the association between the nutritional status and the QTc interval in elderly subjects. The subjects included 119 elderly subjects (46 males and 73 females, age; 72.9±4.8 y) without a history of CVD, who were taking cardioactive drugs. Resting 12-lead electrocardiography was performed, while the QTc interval was calculated according to Bazetts formula. The nutritional status was assessed using a brief self-administered diet history questionnaire. The subjects were divided into three categories, which were defined as equally trisected distributions of the body mass index (BMI). The QTc interval was significantly longer in both the low and high BMI groups than in the moderate BMI group in both genders (p<0.05, respectively). A stepwise multiple regression analysis showed the QTc interval to be independently associated with the potassium intake in the low BMI group and the sodium intake in the high BMI group in both genders (p<0.05, respectively). These results suggest that the body mass, especially lean body mass and overweight, were associated with a prolonged QTc interval and dietary electrolytes in elderly subjects. Based on our results, we consider that it is necessary to perform dietary counseling, especially focusing on sodium and potassium intake, depending on the body mass.

Association between the physical activity and heart rate corrected‐QT interval in older adults

Increased physical activity can reduce the incidence of cardiovascular disease and the mortality rate. In contrast, a prolonged heart rate corrected‐QT (QTc) interval is associated with an increased risk of arrhythmias, sudden cardiac death and coronary artery disease. The present cross‐sectional study was designed to clarify the association between the physical activity level and the QTc interval in older adults.

Interruption in physical activity bout analysis: an accelerometry research issue.

BackgroundThe purpose of the present investigation was to clarify the impact of the treatment of interruptions on the durations and the frequency of the physical activity (PA) bouts under free-living conditions.MethodsOne hundred and forty adults (50 ± 7 years) wore an accelerometer (Lifecorder) for seven consecutive days under free-living conditions. According to the minutes by minutes metabolic equivalents (METs) value, the PA was divided into one of three intensity categories: light intensity PA (LPA, < 3 METs), moderate intensity PA (MPA, 3 to 6 METs), vigorous intensity PA (VPA, > 6 METs), and the sum of the MPA and VPA was defined as moderate to vigorous intensity PA (MVPA, > 3 METs). Thereafter, based on the time series data, we defined MVPA bouts as PA that was maintained at no less than 3 METs completely for 10 minutes or longer with or without allowing for a one-minute or a two-minute break (<3METs).ResultsThe frequency and duration of the continuous MVPA bouts lasting longer than 10-min were significantly lower and shorter compared with that in the non-continuous MVPA bouts allowing a one- or two-minute interruption (4.11 ± 1.65, 6.58 ± 2.72 and 8.97 ± 3.55 bouts/day, 71.62 ± 33.66, 119.03 ± 49.35 and 169.75 ± 65.87 min/day, P < 0.05). The number of days with a total time of MVPA bouts of 30-min was significantly lower in the continuous MVPA bouts compared with that in the non-continuous MVPA bouts allowing a 1-min or 2-min interruption (5.36 ± 1.65, 6.39 ± 1.07 and 6.65 ± 0.85 days/week).ConclusionThe treatment of interruptions for the setting of the accelerometer affects the estimation of the MVPA bouts under free-living conditions in middle-aged to older adults. The best analysis process with regard to the accelerometer quantifying the break to reflect the real behavioral pattern and the physiological stress in such subjects remains unclear.