Relationship between adiponectin and intramuscular fat content determined by ultrasonography in older adults.

Age-associated intramuscular adipose tissue (IntraMAT) deposition induces the development of insulin resistance and metabolic syndrome. However, the relationship between IntraMAT and biochemical parameters in older adults remains unclear. The purpose of this study, therefore, was to elucidate the relationship between adiponectin and echo intensity-estimated IntraMAT using ultrasonography in normal-weight older adults (men 9, women 13) and examine biochemical parameters. Blood tests were performed to determine fasting levels of glucose, insulin, hemoglobin A1c, total cholesterol (Total-C), high-density-lipoprotein cholesterol, low-density-lipoprotein cholesterol (LDL-C), free fatty acid, triglycerides (TGs), adiponectin, leptin, high-sensitivity C-reactive protein, and high-sensitivity tumor necrosis factor, and homoeostasis model assessment index of insulin resistance (HOMA-IR). Mean gray-scale echo intensity was calculated as the IntraMAT index of the vastus lateralis. Waist circumference was measured at the level of the navel as the visceral adipose tissue (VAT) index. Echo intensity was significantly inversely correlated with adiponectin or LDL-C, and that was significantly positively correlated with TG. Adiponectin level was inversely correlated with waist circumference. Partial correlation analysis with waist circumference as the control variable revealed that adiponectin was inversely correlated with echo intensity, independent of waist circumference, whereas no such correlation was observed after controlling for LDL-C and TG levels. When biochemical parameters were grouped in the principal component analysis, among men, Total-C, insulin, and HOMA-IR or hemoglobin A1c, and high-sensitivity tumor necrosis factor-alpha were grouped with the same distribution for factors 1 and 2. Among women, glucose, insulin, HOMA-IR, and Total-C or TGs were grouped with the same distribution for factors 1 and 2. These data suggest that adiponectin level is related to IntraMAT content, independent of VAT in normal-weight older adults. The dynamics of adiponectin might not be similar to those of other circulating biochemical parameters in older men and women.

Effect of electromyostimulation on intramyocellular lipids of the vastus lateralis in older adults: a randomized controlled trial.

BACKGROUND: Excessive intramyocellular lipid (IMCL) accumulation is a primary cause of skeletal muscle insulin resistance, especially in older adults, and interventions that reduce IMCL contents are important to improve insulin sensitivity. Electromyostimulation (EMS)-induced changes in IMCL content in older adults remain unknown. The purpose of this study was to clarify the effects of a single bout of EMS on the IMCL content of the vastus lateralis muscle in older adults. METHODS: Twenty-two physically active, non-obese older men and women were randomly assigned to an EMS intervention group (69.0 ± 5.2 years, n = 12) or a control group (68.4 ± 3.5 years, n = 10). EMS was applied to the vastus lateralis (7 s on and 7 s off) for 30 min; control participants sat quietly for 30 min. IMCL content within the vastus lateralis was quantified with 1H-magnetic resonance spectroscopy (n = 7 per group). Fasting plasma glucose and insulin values were determined from blood samples collected before and after the EMS intervention. RESULTS: EMS induced a significant reduction in plasma glucose (93.1 ± 9.6 to 89.5 ± 9.1 mg/dL, p < 0.01), but not IMCL content (15.7 ± 15.7 to 15.8 ± 13.1 mmol/kg wet weight, p = 0.49) or insulin (5.4 ± 2.4 to 4.7 ± 2.7 µIU/mL, p = 0.18). In the control group, no changes in IMCL content in the vastus lateralis was observed after prolonged quiet sitting. CONCLUSION: EMS intervention for 30 min induces changes in plasma glucose, but no changes in IMCL content in older adults. TRIAL REGISTRATION: University hospital Medical Information Network (UMIN) Center ID: UMIN000020126 . Retrospectively registered on December 222,015. https://upload.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000023242.

Age-related changes in muscle volume and intramuscular fat content in quadriceps femoris and hamstrings.

Whether age-related changes in muscle components differ between the quadriceps femoris and hamstrings has remained unclear. This study aimed to compare the muscle volume and echo intensity-estimated intramuscular adipose tissue content of the vastus lateralis (VL) and long head of biceps femoris (BF) muscles between young and older adults. Thirty young adults (n = 15; mean age, 21 years) and older adults (n = 15; mean age, 71 years) participated in this study. Magnetic resonance imaging was performed to determine muscle volumes of the VL and BF, and muscle volume normalized to body weight (muscle volume/weight). Mean gray-scale echo intensity was calculated as the intramuscular adipose tissue index. Muscle volume/weight and echo intensity were normalized using Z-scores in young and older adults. Muscle volume/weight was lower in older adults than in young adults, and lower in overall women than in men for VL (both p < 0.001) and BF (p < 0.01 and p < 0.05). Echo intensity was higher in older adults than in young adults for VL and BF (both p < 0.001), but did not differ between men and women. Z-score of muscle volume/weight was lower in older adults than in young adults for VL (-2.41 ± 1.22; p < 0.05), and Z-score of echo intensity was higher in older adults than in young adults for BF (2.00 ± 0.68; p < 0.05). These results suggest that muscle volume of quadriceps femoris was lower in older adults than in young adults, whereas intramuscular adipose tissue content of hamstrings was greater in older adults than in young adults.

Relationship between physical activity and intramyocellular lipid content is different between young and older adults.

PURPOSE: Intramyocellular lipid (IMCL) is influenced by physical exercise; however, whether the habitual level of physical activity affects resting IMCL content remains unclear. The purpose of this study was to determine the relationship between physical activity levels and resting IMCL content in young and older adults. METHODS: In total, 15 nonobese young adults (21.0 ± 0.0 years) and 15 older adults (70.7 ± 3.8 years) were recruited. Time spent performing physical activities for 10 days was assessed using a three-dimensional ambulatory accelerometer, and intensity was categorized as light [< 3.0 metabolic equivalents (METs)], moderate (3.0-6.0 METs), or vigorous (> 6.0 METs). Physical activity level was calculated as the product of METs and time spent performing physical activities (MET h) at each intensity level. The IMCL content in the vastus lateralis was determined using 1H-magnetic resonance spectroscopy after overnight fasting. RESULTS: No significant differences in IMCL content were observed between young and older adults. Vigorous intensity physical activity (time and MET h) was significantly lower in older than young adults (p < 0.01); this difference was not observed for light and moderate intensity physical activity. Light intensity physical activity (time and MET h) was significantly and inversely correlated with IMCL content in young adults (r = - 0.59 and r = - 0.58; both p < 0.05), but not in older adults. CONCLUSIONS: These results suggest that daily light intensity physical activity reduces resting IMCL content in young adults, whereas no significant relationship was seen between daily physical activity and resting IMCL content in older adults.

Prolonged effectiveness of 12-month exercise-plus-diet intervention in Japanese adults at risk of impaired glucose or lipid metabolism.

BACKGROUND AND OBJECTIVES: To investigate the prolonged effects of a 12-month exercise-plus-diet intervention in Japanese adults at risk of impaired glucose or lipid metabolism. METHODS AND STUDY DESIGN: A total of 180 participants were randomly divided into an intervention group (n=94), and a control group (n=86). An exercise-plus- diet intervention was conducted on the intervention group for 12 months. The effects were evaluated by questionnaire, physical examinations, and blood tests at baseline, 3 months, 12 months (the end of intervention), and 24 months (one year after the end of intervention). The control group took only the same examinations as the intervention group. RESULTS: At the end of the 12-month intervention, body weight, waist circumference, fasting glucose, HbA1c, triglycerides, and LDL-cholesterol were improved in the intervention group compared to the control group (all p<0.05). One year after the end of the intervention, body weight, waist circumference, fasting glucose, triglycerides, and LDL-cholesterol were still decreased in the intervention group compared to the control group (all p<0.05), especially among non-overweight participants. Among overweight persons, only body weight in the intervention group was lower than the control group. The personal behaviours of physical activity and diet in the intervention group were also improved. CONCLUSIONS: The 12-month exercise-plus-diet programs were found to be effective in improving glucose and lipid metabolism, as well as personal behaviour one year after completion of the intervention.

Three-dimensional comparison of intramuscular fat content between young and old adults.

BACKGROUND: Fat infiltration within skeletal muscle is known as intramuscular fat (IMF), which increases with aging. Studies have assessed IMF content, using the mid-thigh as a representative location. However, three-dimensional IMF distribution is not well understood. The aim of this study was to compare the IMF content in young and old adults by assessing its distribution along the length of the thigh. METHODS: Consecutive transaxial images of the right thighs in 15 young (age, 21.0 ± 0.4) and 15 old (age, 70.7 ± 3.8) were obtained by magnetic resonance imaging. We measured IMF cross-sectional area (CSA), skeletal muscle CSA and calculated volume- and CSA-based IMF content for the quadriceps femoris (QF), hamstring (HM) and adductor (AD). CSA-based calculations were performed at every 10% of femur length (Lf), with 0% Lf and 100% Lf indicating the proximal and distal ends of femur. RESULTS: IMF CSAs along the length of the thigh were similar in both age groups. In contrast, skeletal muscle CSAs in all three muscle groups were significantly lower in old adults than in young adults (variation: -15.2 to -1.6 cm2, P < 0.05). Thus, in volume-based measurements, the older adults had higher IMF contents than the younger adults (9.5% to 14.3% vs. 4.8% to 8.6%, respectively; P < 0.05). However, such age-dependent differences were not observed at the mid-thigh in the QF and AD. CONCLUSION: The results demonstrated an age-related increase in IMF content-confirmed in areas of the thigh-primarily based on finding lower amounts of skeletal muscle mass in CSAs in the older adults.

Associations of intramyocellular lipid in vastus lateralis and biceps femoris with blood free fatty acid and muscle strength differ between young and elderly adults.

The present study aimed to determine relationships between intramyocellular lipid and biochemical profiles or muscle strength in elderly (n = 15; mean age, 71 years) and young (n = 15; mean age, 21 years) male and female adults. Levels of intramyocellular lipid in the vastus lateralis and biceps femoris muscles were determined using 1 H-magnetic resonance spectroscopy. Fasting blood samples were collected to measure levels of glucose, insulin, haemoglobin A1c, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, free fatty acid, triglyceride, adiponectin, and high-sensitivity C-reactive protein. Muscle strength was assessed as maximal voluntary contraction during isometric knee extension. Muscle cross-sectional area in the vastus lateralis was measured using magnetic resonance imaging. Specific force (N cm-2 ) indicating force generation capacity was calculated as muscle strength (N) divided by the muscle cross-sectional area of the vastus lateralis (cm2 ). The intramyocellular lipid content was similar in both muscles in both groups. The intramyocellular lipid content in the biceps femoris significantly correlated with serum free fatty acid levels (r = 0·62, P<0·05), and that in the vastus lateralis significantly and inversely correlated with specific force (r = -0·58, P<0·05) in the young, but not in the elderly adults. The relationship between the intramyocellular lipid content in the thigh muscles and biochemical profiles, or specific force differed between elderly and young adults. Age-associated changes in morphology, function and metabolic factors apparently influence intramyocellular lipid metabolism in the thigh muscles.

Skeletal muscle size is a major predictor of intramuscular fat content regardless of age.

PURPOSE: Skeletal muscles of older individuals have a larger amount of intramuscular adipose tissue (IntraMAT) than those of younger individuals. It is not understood how aging affects the IntraMAT content of individual muscles of the thigh. We assessed the relationship between IntraMAT content and skeletal muscle cross-sectional area (CSA), subcutaneous adipose tissue CSA, biochemical blood profiles, and physical activity. METHODS: Fifteen older (70.7 ± 3.8 years) and 15 younger (20.9 ± 0.3 years) men and women participated in this study. Magnetic resonance imaging of the right thigh was taken to measure IntraMAT content and skeletal muscle CSA for the quadriceps femoris (QF), hamstrings (HM), adductor (AD) muscle groups and subcutaneous adipose tissue CSA of the thigh. Fasting blood samples were collected to measure plasma lipids, adiponectin, and HbA1c levels. RESULTS: IntraMAT content in QF, HM, and AD for the Older group was significantly higher than in the Younger group. However, skeletal muscle CSA normalized by body weight (skeletal muscle CSA/bw) in the QF (P < 0.001) and total thigh (P < 0.01) were significantly lower in the Older group compared with the Younger group.There were no significant differences in HM and AD. Stepwise regression analysis with IntraMAT content as a dependent variable revealed that skeletal muscle CSA/bw of the thigh was the only predictive variable for IntraMAT content in Older and Younger groups. CONCLUSION: These results suggest that skeletal muscle size could be a major determinant of IntraMAT content regardless of age.

The significant drop in physical activity among children on holidays in a small town in the Tohoku district.

In Japan, there is a higher incidence of childhood obesity in the Tohoku district than in other areas. It is known that reduced physical activity is associated with increased body weight, but little is known about the physical activity patterns of children in this area. Accordingly, this study was designed to measure the physical activity of 145 children (73 boys and 72 girls) in Hashikami Town, Aomori Prefecture. Physical activity was assessed through a questionnaire as well as through two weeks of pedometer use. Boys spent more time engaging in physical activity than girls did, reporting 9.5 (0.6-22.0) versus 7.0 (1.2-21.5) hours per week [median (range)] (p=0.002). On school days, boys took an average of 13,586+/-4,386 (mean+/-SD) steps per day, while girls took 12,248+/-4,112; on holidays, boys took 9,531+/-4,557, while girls took 9,419+/-4,524. There was no significant sex-based difference in the number of steps per day (F=1.197, p=0.276), but both boys and girls significantly reduced the number of steps they took on holidays (F=116.537, p<0.001). In addition, 36 (24.8%) children reduced the number of steps they took by more than 50% on holidays compared to school days. In general, the participants engaged in the internationally recommended amounts of physical activity. Yet their reduced level of physical activity on holidays seems to be a matter for concern, as it is a possible cause of the higher incidence of childhood obesity in this area.

Daily walking activity among male office workers in a rural town in northern Japan.

To investigate the level of walking activity among residents of the Tohoku district in northern Japan, where no widespread public transport system has been developed, winter is severe. The participants were 50 town hall employees with an average age of 43.6+/-10.8 (SD) years. The walking activity of each participant was assessed using a pedometer for one week in summer and one week in winter. The participants' lifestyles, including their commuting methods, were assessed using a questionnaire. Forty-six participants (92%) usually commute to work by private car. The average numbers of steps/day on workdays and holidays were, in summer, 6,560+/-2,600 and 7,016+/-4,679, respectively, and, in winter, 5,236+/-2,253 and 4,770+/-3,039; these numbers were somewhat lower than those recorded in previous reports. We observed a significant reduction in walking during winter (F=19.016, p=0.0001), but no significant differences between workdays and holidays (F=0.001, p=0.966). A significant correlation between BMI and steps/day (r=-0.420, p<0.01) was obtained on workdays in winter. The unexpectedly low level of these participants' physical activity, especially in winter, is probably due to the fact that most of them commute by private car, which is likely a cause of the high incidence of obesity in this district. In addition, a seasonal effect should also be considered when physical activity is assessed, especially in cold climates.

Pedometer-determined physical activity and indicators of health in Japanese adults.

Recently, many cross-sectional studies observed that body mass index (BMI) and percentage of body fat (%BF) were inversely associated with pedometer-determined physical activities, but studies on Asian populations, including the Japanese, are sparse. Height, weight, body fat percentage (%BF, bioelectrical impedance analyzer), and waist circumference were measured on 117 women (62.8+/-4.5 years, 22.2+/-2.2 kg/m(2)) and 62 men (64.0+/-4.6 years, 23.6+/-2.5 kg/m(2)). Pearson correlations and partial correlation coefficients after controlling for age were calculated between steps/day and variables. Furthermore, participants were classified into four groups as follows: <5,000, 5,000-7,499, 7,500-9,999, and >or=10,000 steps/day, and analyzed using ANOVA across activity groups. In women, a significant correlation was found between steps/day and BMI (r=-0.217, p=0.018), %BF (r=-0.292, p=0.0014), and the relationship was still significant after controlling for age. The relationship between steps/day and waist circumference was not significant. In men, a significant relationship was not observed between steps/day and obesity indices. The correlations between steps/day and both BMI and %BF were significant in Japanese women, but weak compared with Caucasian and African-American women as reported previously. A possible cause is racial difference in degree of obesity and body shape. The effects of physical activity on body shape and composition may differ according to race.

Gentle exercise of 40 minutes with dietary counseling is effective in treating metabolic syndrome.

Obese people may succeed in reducing their weight temporarily, but most of them regain the lost weight within a few years. We, therefore, recommend moderate long-term changes in habit rather than a strict temporary program. The purpose of this study was to examine whether physical activity of 40 minutes, mainly walking, was effective in improving or preventing metabolic syndrome when combined with dieting. Participants, all of whom had a waist circumference >or= 85 cm (men) or >or= 90 cm (women), were assigned into one of two groups: the control group (10 men and 11 women, age: 64.2 +/- 3.4 [SD] years) and the intervention group (10 men and 12 women, age: 62.4 +/- 4.2 years). Participants (n = 22) enrolled in a 52-week program; their diets were assessed using a 3-day dietary record and daily steps were measured with a pedometer. No significant change was seen in their dietary records, but the mean number of daily steps increased from 5,806 to 8,000-9,000. In the intervention group, BMI, waist circumference, and systolic and diastolic blood pressures decreased significantly by week 12 (all p < 0.001) and remained low until week 52. In fact, no significant change was seen between weeks 12 and 52. The control group showed no significant changes in all variables. These results indicate that gentle exercise of about 40 minutes in combination with dieting is effective in preventing metabolic syndrome among a sedentary population, although its effect may be limited.

Accuracy of body fat assessment by bioelectrical impedance in Japanese middle-aged and older people.

Bioelectrical impedance analysis (BIA) is commonly used to measure the percentage of body fat (%BF), but its accuracy is controversial. In addition, the equations are specific to the group for which they were established. As far as we know, there is no study examining the accuracy of BIA in Japanese middle-aged and older people. We compared %BF assessed using BIA with that of dual-energy X-ray absorptiometry (DEXA) in 102 female and 51 male local residents aged 40 to 78 y. Simple correlation coefficients were 0.79 for females and 0.69 for males, which are statistically significant (p<0.001). However, BIA tended to overestimate %BF in the lower BF group and underestimate it in the BF higher group, and only 45.1% for female and 47.1% for male subjects were measured accurately, i.e., within 10% of the measurement by DEXA. This result suggests that this model of BIA is an alternative for estimating %BF in Japanese middle-aged and older people as well as when subjects are within a normal body fat range, but greater accuracy is needed for lean and overweight subjects.

Small bowel bacterial overgrowth is not seen in healthy adults but is in disabled older adults.

BACKGROUND/AIMS: Small bowel bacterial overgrowth (SBBO) is defined as an abnormal increase in the number of bacteria in the small intestine, and may be occult in older adults. The aim of this study was to determine whether small bowel bacterial overgrowth (SBBO) is found in healthy older people as a concomitant of normal aging or is seen only in disabled or frail older people, excluding patients with intestinal disease and those who had undergone upper intestinal or gastric surgery. METHODOLOGY: Forty-one relatively healthy older people, aged 74.6 +/- 1.7 (mean +/- SE) years, who engage in regular exercise, and 42 variously disabled older people, average age 78.8 +/- 1.1 years, who commute to a day-care center participated in this study. SBBO was determined by a breath hydrogen (H2) test after ingestion of 50g of glucose solution dissolved in 200mL of water. Physical activity was judged from the number of steps walked per day as measured by a pedometer. Food intake was assessed by an interview. RESULTS: No SBBO-positive subject was seen among the healthy, while 11 (25.6%) of the disabled older adults were positive. The number of steps/day taken by the disabled subjects was extremely low, only 22.3% of that of the healthy (P<0.001). No significant difference was seen between the groups in food intake. The mean age of the SBBO-positive patients was relatively high, 81.5 +/- 2.2 years, and 5 (45.4%) of them were underweight, with a BMI<18.5. CONCLUSIONS: Our results and previous studies indicate that SBBO is seen only in patients with intestinal disease and disabled or frail older people.

Small bowel bacterial overgrowth may not affect bone mineral density in older people.

BACKGROUND & AIMS: Small bowel bacterial overgrowth (SBBO) may be associated with malnutrition, diarrhea, and weight loss. Recently, bone mineral density (BMD) in patients with SBBO was reported to be lower, and SBBO may be an important factor in the development of metabolic bone disease. However, the subjects in these studies were relatively young patients with intestinal diseases. There is no information on the effect of SBBO on BMD in older people. METHOD: Seventeen relatively active and 33 disabled older people participated in this study. SBBO was determined by a breath hydrogen (H2) test after ingestion of a glucose solution. BMD of the lumbar spine and femur were measured using a dual energy X-ray absorptiometry scan (DEXA). RESULTS: One healthy control and 11 disabled subjects were SBBO-positive. The Z-scores of the lumbar spine were not statistically different between groups, and a high incidence of disorders, >70%, was seen in all groups. On the other hand, there were significant differences in the femoral BMD between the healthy controls and the SBBO-negative (P<0.001) and SBBO-positive (P<0.05) groups. No significant difference was seen in femoral BMD between SBBO-positive and SBBO-negative institutionalized people. CONCLUSION: SBBO seems to have little effect on BMD in people approximately 80 years old.