Association of skeletal muscle oxidative capacity with muscle function, sarcopenia-related exercise performance, and intramuscular adipose tissue in older adults.

Muscle function and exercise performance measures, such as muscle endurance capacity, maximal strength, chair stand score, gait speed, and Timed Up and Go score, are evaluated to diagnose sarcopenia and frailty in older individuals. Furthermore, intramuscular adipose tissue (IntraMAT) content increases with age. Skeletal muscle oxidative capacity determines muscle metabolism and maintains muscle performance. This study aimed to investigate the association of skeletal muscle oxidative capacity with muscle function, exercise performance, and IntraMAT content in older individuals. Thirteen older men and women participated in this study. Skeletal muscle oxidative capacity was assessed by the recovery speed of muscle oxygen saturation after exercise using near-infrared spectroscopy from the medial gastrocnemius. We assessed two muscle functions, peak torque and time to task failure, and four sarcopenia-related exercise performances: handgrip strength, gait speed, 30-s chair stand, and Timed Up and Go. The IntraMAT content was measured using axial magnetic resonance imaging. The results showed a relationship between skeletal muscle oxidative capacity and gait speed but not with muscle functions and other exercise performance measures. Skeletal muscle oxidative capacity was not related to IntraMAT content. Skeletal muscle oxidative capacity, which may be indicative of the capacity of muscle energy production in the mitochondria, is related to locomotive functions but not to other functional parameters or skeletal fat infiltration.

Relationship between trunk intramuscular adipose tissue content and prevalence of metabolic syndrome in middle-aged Japanese men.

OBJECTIVES: The aim of the present study was to examine the dose-response relationship between trunk tissue composition and prevalence of metabolic syndrome (MetS) in middle-aged Japanese men. METHODS: The 1026 men (between 35 and 59 y of age) who participated in the present study were divided into two groups: those with metabolic syndrome (MetS) and those without (non-MetS). Intramuscular adipose tissue (IntraMAT) content and the cross-sectional areas (CSAs) of visceral adipose tissue and skeletal muscle tissue were calculated using low-dose computed tomography images acquired at the level of the third lumbar vertebra. Height, body mass, body fat, waist circumference, the presence of MetS, and lifestyle habits were also assessed. RESULTS: IntraMAT content was significantly higher in MetS than in non-MetS men. A 10% increase in IntraMAT content correlated with the prevalence of MetS (odds ratio, 4.197; 95% confidence interval, 3.108-7.088; P < 0.001), even after adjustments for age, height, adjusted skeletal muscle CSA, sleeping time, alcohol consumption, exercise habit, and cigarette smoking. Skeletal muscle CSA did not correlate with the prevalence of MetS after adjustments for IntraMAT content and other cofactors. CONCLUSIONS: Increase in IntraMAT content, not in skeletal muscle CSA, significantly correlated with the prevalence of MetS. These results suggest that countermeasures against the accumulation of trunk IntraMAT effectively prevent MetS in middle-aged Japanese men.

Dynamic adjustment of submaximal effort soccer side-foot kicks.

We aimed to illustrate kicking leg dynamics during submaximal effort soccer side-foot kicks. Side-foot kicks with three effort levels (50, 75 and 100% effort levels based on maximal effort) of eight male university soccer players were captured (500 Hz) while initial ball velocities were monitored simultaneously. Systematic regulation in joint kinetics (angular impulses) was clearly demonstrated for hip flexion and knee extension moments thereby supporting the interpretation that the final foot velocity is controlled in a context of a planar, sequential segmental system. Out of the thigh-shank plane motion (hip external rotation moment) was also found to be systematically adjusted. Kinematic contributions of knee extension angular velocity to the final foot velocity increased significantly in the maximal effort while that of hip external rotation reduced significantly, coinciding with a more straightforward approach-run. The adjustable range of the foot-ball interaction was found to be rather smaller in side-foot kicks. However, significantly smaller ball/foot velocity ratios in the two submaximal conditions suggested ankle joint fixation was manipulated towards ball impact. Players and coaches ought to recognise that the intensities of side-foot kicks were regulated by the motions within and without the thigh-shank plane alongside several kinematic changes.

Neuromuscular activation of the quadriceps femoris, including the vastus intermedius, during isokinetic knee extensions.

The purpose of this study was to compare the neuromuscular activation patterns of the individual muscles of the quadriceps femoris (QF), including the vastus intermedius (VI), during isokinetic concentric (CON) and eccentric (ECC) contractions. Thirteen healthy men performed maximum isokinetic CON and ECC knee extensions at angular velocities of 30, 90, and 120°/sec at knee joint angles from 80 to 180° (180° = full extension). The surface electromyographic (EMG) activities of the four individual muscles of the QF were recorded. The root mean squares of the EMG signals were normalized by the root mean square (nRMS) during CON contraction at 30°/sec. To investigate the nRMS changes, we classified the range of motion into four subcategories for each CON and ECC contraction. The nRMS of the VI was significantly higher in the flexed position during CON and ECC contractions at all velocities, and gradually decreased toward the extended positions regardless of the type of muscle contraction or angular velocity. These results suggest that the QF undergoes neuromuscular activation in a joint angle-dependent manner. In particular, the VI may contribute greatly during flexed contractions, independent of the type of contraction and angular velocity.

Passive muscle stiffness is correlated with the intramuscular adipose tissue in young individuals.

PURPOSE: We investigated the relationship between intramuscular adipose tissue (IntraMAT) and muscle stiffness (passive and mechanical) and lengthening in young individuals, hypothesizing that (1) passive muscle stiffness is negatively correlated with the IntraMAT content, and (2) the IntraMAT content is negatively correlated with mechanical changes in muscle stiffness and fascicle length during passive dorsiflexion. METHODS: Twenty men and women (20.3 ± 1.3 years) participated in this study. Axial T1-weighted magnetic resonance imaging was performed at the thickest point of the medial gastrocnemius (MG) to measure the IntraMAT cross-sectional area (CSA) and muscle tissue CSA (units; cm2). The shear wave velocity (SWV) and fascicle length at the three ankle joint angles, namely 15° with plantarflexion (PF15), 0° with neutral position (NP), and 15° with dorsiflexion (DF15), were measured as parameters of muscle stiffness (unit; m/s) and lengthening (unit; cm) using ultrasound shear wave elastography and B-mode imaging. We further calculated the changes in SWV and fascicle length from PF15 to NP and from NP to DF15 as mechanical muscle stiffness and lengthening, respectively. RESULTS: There was a relationship between IntraMAT CSA and absolute SWV at DF15 (r = - 0.47, P < 0.05). Further, a relationship was observed between IntraMAT CSA and change in SWV and fascicle length from NP to DF15 (r = - 0.47 and r = 0.59, P < 0.05); whereas no relationship was observed between changes in fascicle length and muscle SWV (r = - 0.23, P = 0.33). CONCLUSION: These results may indicate biomechanical and/or physiological associations between IntraMAT CSA and passive muscle stiffness.

Relative contribution of neuromuscular activation, muscle size, and muscle quality to maximum strength output of the thigh muscles in young individuals.

This study aimed to investigate the relationship between maximal muscle strength and neuromuscular activation, muscle size, and quality of quadriceps (QF) and hamstring muscles (HM). The study included 24 young men and women. The neuromuscular activation parameter was recorded using a single-channel surface electromyography (EMG) with the root mean square (RMS) during maximal isometric knee extension and flexion from four muscles: rectus femoris and vastus lateralis for QF; biceps femoris and semitendinosus for HM. In addition, the peak torque was measured during the same session. B-mode ultrasonographic transverse images were obtained from the anterior, lateral, and posterior thighs. Furthermore, we calculated the muscle thickness (MT) and echo intensity (EI) of the four muscles as indicators of muscle size and quality. The averaged MT, EI, and absolute RMS of QF were calculated by averaging the values of the rectus femoris and vastus lateralis, and that of HM was calculated by averaging the values of the biceps femoris and semitendinosus. The knee extension peak torque was correlated with EI (r = -0.61, P < 0.01) and RMS (r = 0.53, P < 0.01) in the QF. In contrast, the knee flexion peak torque was correlated with RMS (r = 0.53, P < 0.05) but not with MT and EI in HM. In addition, EI and RMS in QF, and RMS in HM were selected as the major determinants of muscle strength in the stepwise regression analysis. These results suggest that muscle strength is moderately associated with different factors related to the thigh muscles in young individuals.

Effect of subcutaneous adipose tissue and muscle thicknesses on rectus femoris and vastus intermedius ultrasound echo intensities: a cadaver study.

PURPOSE: The purpose of this study was to examine the effect of subcutaneous adipose tissue (SCAT) thickness and rectus femoris (RF) muscle thickness on RF and vastus intermedius (VI) echo intensity using human cadavers. METHODS: The echo intensity of the RF and VI was measured in 11 legs of seven cadavers under three conditions: intact condition (Model 1), SCAT removed (Model 2), and SCAT and RF removed (Model 3). RESULTS: RF echo intensity in Model 1 (69.2 ± 20.3 a.u.) was significantly lower than that in Model 2 (83.4 ± 15.9 a.u.) (P = 0.003). VI echo intensity in Models 1 to 3 showed similar results to RF echo intensity (P = 0.003 to 0.001). Regarding the relationship between VI echo intensity and VI muscle thickness, the regression lines shifted upward in a parallel fashion in the order Model 1, Model 2, and Model 3. Multiple regression analysis revealed that the variation in RF echo intensity was explained by RF muscle thickness (P = 0.036) and SCAT thickness (P = 0.001), while the variation in VI echo intensity was explained by RF muscle thickness (P = 0.035). CONCLUSION: These results suggest that SCAT thickness and RF muscle thickness induce lower RF echo intensity, while RF muscle thickness induces lower VI echo intensity.

Factors related to trunk intramuscular adipose tissue content - A comparison of younger and older men.

The present study investigated factors related to trunk intramuscular adipose tissue (IntraMAT) content in younger and older men. Twenty-three healthy younger (20 to 29 years) and 20 healthy older men (63 to 79 years) participated in this study. The trunk IntraMAT content was measured using magnetic resonance imaging at the height of the 3rd lumbar vertebra. In addition to blood properties and physical performance, dietary intake was assessed by a self-administered diet history questionnaire. The dietary intake status was quantified using the nutrient adequacy score for the intake of 10 selected nutrients by summing the number of items that met the criteria of dietary reference intakes for Japanese individuals. The results obtained revealed that the trunk IntraMAT content was significantly higher in the older group than in the younger group (p < 0.05). In the younger group, the trunk IntraMAT content significantly correlated with systolic and diastolic blood pressure and HbA1c (rs = 0.443 to 0.464, p < 0.05). In the older group, significant and negative correlations were observed between the trunk IntraMAT content and 5-m usual walking speed, handgrip strength, and nutrient adequacy scores (rs = -0.485 to -0.713, p < 0.05). These results indicate that factors associated with the trunk IntraMAT content differed in an age dependent manner. In the younger group, the trunk IntraMAT content correlated with the metabolic status such as blood pressure and HbA1c. In the older group, physical performance and the dietary intake status negatively correlated with the trunk IntraMAT content.

Importance of skeletal muscle lipid levels for muscle function and physical function in older individuals.

The skeletal muscle contains lipids inside (intramyocellular lipids, IMCL) or outside (extramyocellular lipids, EMCL) its cells. The muscle lipid content increases with age; however, the characteristics of IMCL and EMCL in older individuals are not well known. We aimed to examine the characteristics of skeletal muscle lipids by investigating their relationship with muscle function and physical functions. Seven elderly men and 16 elderly women participated. The skeletal muscle lipid content, including IMCL and EMCL, was measured in the vastus lateralis by proton magnetic resonance spectroscopy. Isometric knee extension with maximal voluntary contraction (MVC) and time-to-task failure for knee extension with 50% MVC were measured as muscle functions. The participants performed six physical function tests: preferred gait speed, maximal gait speed, Timed Up and Go, chair sit-to-stand, handgrip strength, and stand from the floor. The time to knee extension task failure had a significant relationship with the IMCL (rs = -0.43, P < 0.05), but not with the EMCL content. Significant relationships were confirmed in the EMCL content with the sit-to-stand (rs = -0.48, P < 0.05) and stand-from-the-floor (rs = 0.53, P < 0.05) tests. These findings indicated that muscle lipids are associated with muscle and physical functional performances in older individuals. Novelty: No relationship was confirmed between IMCL and EMCL in older individuals. Muscle endurance performance had a relationship with IMCL, but not with EMCL. Relationships between EMCL and physical functional tests (e.g., sit-to-stand and stand from the floor) were confirmed.

Skeletal muscle and abdominal circumference explain intramuscular fat, independent of exercise frequency, in middle-aged Japanese men.

The purpose of this study was to examine how intramuscular adipose tissue (IntraMAT) can be characterized using physical and functional characteristics, muscle size, and/or adipose tissue in four different exercise frequency groups of middle-aged Japanese men. One thousand twenty-eight middle-aged men (age, 47.5 ± 8.1 years; height, 170.5 ± 5.8 cm; body mass, 67.0 ± 9.3 kg; body mass index, 21.9 ± 5.3 kg/m2) were allocated to four groups on the basis of their weekly exercise frequency: Group 1, no exercise, n = 334; Group 2, once a week, n = 271; Group 3, a few days a week, n = 269; and Group 4, every day, n = 154. Their body composition, blood pressure, and handgrip strength were assessed. A single-slice computerized tomography image at the level of the umbilicus was acquired and the CSAs of IntraMAT, muscle tissue, and subcutaneous and visceral adipose tissues (SCAT and VAT) were calculated. The %IntraMAT significantly correlated with physical characteristics, such as age, BMI, abdominal circumference, and muscle tissue CSA. Stepwise multiple regression analysis was performed, with the %IntraMAT as the dependent variable. Muscle tissue CSA and abdominal circumference were the common independent variables across groups to explain the variability of the %IntraMAT. It was also extracted %body fat and age for Group 2, age, handgrip strength, and BMI for Group 3, and smoking category for Group 4. These results suggested that muscle tissue size and abdominal circumference would be the strong predictors to explain %IntraMAT of the trunk muscle across four groups, and that age, %body fat, BMI, and SCAT, handgrip strength and smoking category were also good predictors for each group with different exercise frequency in middle-aged Japanese men.

Contribution of skeletal muscle and serum lipids to muscle contraction induced by neuromuscular electrical stimulation in older individuals.

Intramyocellular lipids (IMCL) stored in droplets in muscle cells and free fatty acids (FFA) from fat cells in the blood are the main substrates of adenosine triphosphate during continuous muscle contractions of relatively lower intensity. Although it is known that the lipid oxidative capacity decreases with aging, the effect of IMCL and FFA on muscle contraction in older individuals remains unclear. The purpose of this study was to investigate the contribution of skeletal muscle lipids and blood lipids as energy sources for muscle contraction in older individuals. Eighteen older individuals (mean age: 70.4 ± 3.5 years) underwent muscle contraction intervention induced by intermittent neuromuscular electrical stimulation (NMES) to the vastus lateralis for 30 min. Fasting blood samples were obtained and proton magnetic resonance spectroscopy (1 H-MRS) was performed before and after NMES, and the parameters (including IMCL and extramyocellular lipid [EMCL]) from 1 H-MRS, along with FFA and adiponectin levels, were analyzed using the blood samples of all participants. Levels of IMCL and EMCL did not change (p > 0.05); however, FFA and adiponectin levels decreased from 1.1 ± 0.5 mEq/L to 0.8 ± 0.2 mEq/L and 12.0 ± 5.3 µg/ml to 11.4 ± 5.0 µg/ml, after NMES (p < 0.05), respectively. These findings indicate that serum lipids, but not skeletal muscle lipids, are the energy substrate utilized during involuntary muscle contraction in older individuals.

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.

Brown adipose tissue fat-fraction is associated with skeletal muscle adiposity.

PURPOSE: While brown adipose tissue (BAT) activity is known to be associated with both muscle and adipose tissue volumes, the association between BAT and muscle composition remains unclear, especially in adults. Therefore, the present study aimed to examine the association between BAT parameters (glucose uptake and fat-fraction) and muscle volumes and intramuscular adipose tissue contents among healthy young and middle-aged men. METHODS: BAT glucose uptake was determined using positron emission tomography with [18F]-2-deoxy-2-fluoro-D-glucose (18F-FDG) during cold exposure in 19 young and middle-aged men (36.3 ± 10.7 years). The fat-fraction of BAT was determined from volumes of interest set in cervical and supraclavicular adipose tissue depots using signal fat-fraction maps via magnetic resonance imaging (MRI). Muscle volumes and intramuscular adipose tissue contents of m. tibialis anterior and m. multifidus lumborum were measured using MRI. RESULTS: The fat-fraction of BAT was significantly associated with intramuscular adipose tissue content in m. tibialis anterior (n = 13, rs = 0.691, P = 0.009). A similar trend was also observed in m. multifidus lumborum (n = 19, rs = 0.454, P = 0.051). However, BAT glucose uptake was not associated with intramuscular adipose tissue contents in both muscles, nor were muscle volumes associated with the BAT glucose uptake and fat-fraction. CONCLUSION: The fat-fraction of BAT increases with skeletal muscle adiposity, especially in the lower leg, among healthy young and middle-aged men.

Relationship between physical activity time and intramuscular adipose tissue content of the thigh muscle groups of younger and older men.

We investigated the effect of physical activity on muscle tissue size and intramuscular adipose tissue (IntraMAT) content in the thigh muscle groups of younger and older men. Twenty younger and 20 older men participated in this study. The muscle tissue cross-sectional area (CSA) and the IntraMAT content in the quadriceps femoris (QF), hamstrings (HM), hip adductors (AD), and mid-thigh total were measured using magnetic resonance imaging. The physical activity time was measured using a triaxial accelerometer, and four levels of physical activity were determined depending on the metabolic equivalent of task (METs), including sedentary (≤ 1.5 METs), light intensity (≤ 2.9 METs), moderate intensity (3.0-5.9 METs), and vigorous intensity (≥ 6.0 METs). No significant correlation was observed between the physical activity parameters and muscle tissue CSA in both groups. The IntraMAT content of the three muscle groups (QF, AD, and HM) and the total thigh was inversely correlated with the time of moderate-intensity physical activity (rs = - 0.625 to - 0.489, P < 0.05, for all comparisons) in the young group, but not in the older group. These results indicate that IntraMAT accumulation was associated with the amount of moderate-physical activity in younger men.

Evaluation of rehabilitation exercise effects by using gradation-based skeletal muscle echo intensity in older individuals: a one-group before-and-after trial study.

BACKGROUND: Higher muscle echo intensity (EI) reflects higher content of fat and/or connective tissue within skeletal muscle, eventually inducing lower muscle strength, physical dysfunction, and metabolic impairment. Continuous exercise decreases muscle EI in older individuals; however, it is not well understood how several months' rehabilitation exercise affects gradation-based EI. The purpose of this study was to investigate the effects of 6 months of rehabilitation exercise on gradation-based higher and lower EI in older men and women. METHODS: Twenty-seven men and women (7 men, 20 women; age, 75.6 ± 6.4 years; height, 154.3 ± 8.5 cm; weight, 55.8 ± 9.7 kg) participated in this study. This study was a one-group before-and-after trial. They needed long-term care for activities of daily living. They performed rehabilitation exercises consisting of resistance exercises using a hydraulic resistance machine, stretching, and aerobic exercises using a recumbent bicycle once or twice a week for 6 months. B-mode ultrasonographic transverse image was taken from thigh muscles, e.g., rectus femoris, vastus lateralis, and biceps femoris. We calculated gradation-based cross-sectional area (CSA) from thigh muscles by dividing 256 greyscale level to 10 different components levels (e.g., 0-24, 25-49, 50-74, …, 200-224 and 225-249 a.u.). RESULTS: Lowest EI (e.g., 0-24 a.u.) CSA of thigh muscle was significantly increased after the exercise (0.3 ± 0.3 to 1.0 ± 0.8 cm2; P < 0.05). Middle to higher EI (e.g., 50-74, 75-99, 100-124, 125-149, 150-174, 175-199 and 200-224 a.u.) CSAs were significantly decreased from 23.0 to 68.7% after the exercise (P < 0.05). CONCLUSIONS: Several months' rehabilitation exercise affected both lower and higher EI in older men and women. This result suggests that rehabilitation exercise changes muscle composition by increasing contractile muscle tissue and decreasing fat and connective tissues.

Comparison of metabolic risk factors, physical performances, and prevalence of low back pain among categories determined by visceral adipose tissue and trunk skeletal muscle mass in middle-aged men.

The present study compared metabolic risk factors, physical performances, and musculoskeletal impairment among categories determined by visceral adipose tissue (VAT) and trunk skeletal muscle (SM) mass in middle-aged Japanese men. In total, 1026 healthy Japanese males aged between 35 and 59 years were categorized into 4 groups according to the amount of VAT and SM in the trunk measured using low-dose computed tomography (LowVAT-HighSM, LowVAT-LowSM, HighVAT-HighSM, and HighVAT-LowSM). Height, body mass waist circumference, body fat, intramuscular adipose tissue (IntraMAT), subcutaneous adipose tissue, biochemical blood profiles (triglycerides, high-density lipoprotein cholesterol, fasting blood glucose, aspartate transaminase, alanine transaminase and γ-glutamyl trans peptidase), physical performances (trunk flexibility, the chair-stand test, two-step length and hand-grip strength), the prevalence of low back pain, and lifestyle habits for exercise, alcohol intake and smoking, were compared among the groups. The results showed that LowVAT-HighSM had significantly superior biochemical blood profiles and physical performances to the other groups. HighVAT-LowSM had significantly higher %IntraMAT and the prevalence of low back pain. The two-step length, which is an index of walking ability, significantly differed according to the four subject categories. These results indicate that metabolic risk factors, physical performances, and prevalence of low back pain in middle-aged Japanese men may differ among four categories determined by VAT and trunk SM.

Chair sit-to-stand performance is associated with diagnostic features of sarcopenia in older men and women.

BACKGROUND: Standing from a chair is a fundamental activity of daily living, and it can be applied to assess the physical function, especially in older individuals. AIM: The aim of this study was to elucidate the characteristics of mechanical and temporal parameters during chair stand based on the relationship with skeletal muscle and physical functional parameters in older men and women. METHODS: Eighty older men and women participated in this study. We measured four parameters of chair stand performance: ground reaction force (GRF), rate of force development (RFD), and chair rise time (CRT) were calculated from the foot-floor force data; sit-to-stand (STS) was also assessed by measuring the time needed to complete 10 chair stand repetitions. The muscle thickness (MT) and echo intensity, as indexes of muscle size and quality, respectively, were measured using axial B-mode ultrasound images from quadriceps femoris. The gait speed and handgrip strength were measured as physical functional parameters. RESULTS: Partial correlation was used to determine the association of chair stand performance with MT, echo intensity, and physical parameters while considering the height, body mass, and age. GRF, RFD, and STS were significantly correlated with MT (r = 0.35, 0.26, and -0.49), gait speed (r = 0.32, 0.31, and -0.67), and handgrip strength (r = 0.57, 0.59, and -0.49). As the result of regression analysis, MT, gait speed, and handgrip strength were estimated by GRF and STS. CONCLUSION: These results suggest that chair stand performance is useful as it reflects the muscle size and physical functions in older individuals.

Effects of Aerobic, Resistance, or Combined Exercise Training Among Older Adults with Subjective Memory Complaints: A Randomized Controlled Trial.

BACKGROUND: Physical exercise is suggested to be effective for preventing cognitive decline in older adults, but the relative efficacy of different types of exercise have yet to be clarified. OBJECTIVE: This single-blinded randomized controlled trial was designed to investigate the differential effects of aerobic exercise training (AT), resistance exercise training (RT), and combined exercise training (CT) on cognition in older adults with subjective memory complaints (SMC). METHODS: Community-dwelling older adults with SMC (n = 415; mean age = 72.3 years old) were randomly assigned to one of the four groups: AT, RT, CT, or control group. The study consisted of two phases: a 26-week intervention and a 26-week follow-up. The participants were evaluated at baseline, 26 weeks (postintervention), and 52 weeks (follow-up). The primary outcome of this study was memory function, which was assessed using the Logical Memory II subtest of the Wechsler Memory Scale-Revised (WMS-R) score. The secondary outcomes included global cognitive function, verbal fluency, working memory, processing speed, and executive functions. RESULTS: Intention-to-treat analysis by a mixed-effect model repeated measure showed that the AT group had significantly improved performance on the WMS-R Logical Memory II test (2.74 [1.82-3.66] points) than the control group (1.36 [0.44-2.28] points) at the postintervention assessment (p = 0.037). The effect was more pronounced in those without amnesia than those with amnesia. No significant improvement was observed in the RT and CT groups. CONCLUSION: This study suggests that AT intervention can improve delayed memory in community-dwelling older adults, particularly in individuals without objective memory decline.

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.