Project description:The construct of sarcopenia is still discussed with regard to best appropriate measures of muscle volume and muscle function. The aim of this post-hoc analysis of a cross-sectional experimental study was to investigate and describe the hierarchy of the association between thigh muscle volume and measurements of functional performance in older women. Thigh muscle volume of 68 independently living older women (mean age 77.6 years) was measured via magnetic resonance imaging. Isometric strength was assessed for leg extension in a movement laboratory in sitting position with the knee flexed at 90° and for hand grip. Maximum and habitual gait speed was measured on an electronic walk way. Leg muscle power was measured during single leg push and during sit-to-stand performance. Thigh muscle volume was associated with sit-to-stand performance power (r = 0.628), leg push power (r = 0.550), isometric quadriceps strength (r = 0.442), hand grip strength (r = 0.367), fast gait speed (r = 0.291), habitual gait speed (r = 0.256), body mass index (r = 0.411) and age (r = -0.392). Muscle power showed the highest association with thigh muscle volume in healthy older women. Sit-to-stand performance power showed an even higher association with thigh muscle volume compared to single leg push power.
Project description:BackgroundWe aimed to explore the associations between thigh muscle fat density and vascular events.MethodsA total of 3,595 adults (mean age, 57.2 years; women, 1,715 [47.7%]) without baseline cardiovascular events from the Korean Atherosclerosis Study-2 were included. Muscle and fat area at the mid-thigh level were measured by computed tomography (CT) using the following Hounsfield Unit range: 0-30 for low density muscle (LDM); 31-100 for normal density muscle (NDM); and - 250 to - 50 for fat.ResultsDuring a median follow-up period of 11.8 (4.3-13.9) years, vascular events occurred in 11.6% of men and 5.9% of women. Individuals with vascular events had a larger LDM area (men: 48.8 ± 15.5 cm2 vs. 44.6 ± 14.5 cm2; women: 39.4 ± 13.2 cm2 vs. 35.0 ± 11.8 cm2, both P < 0.001) compared with those who did not have vascular events during the follow-up of at least 5 years. The LDM/NDM ratio was also independently associated with vascular events after adjusting for cardiometabolic risk factors. Moreover, the LDM/NDM ratio improved the prognostic value for vascular events when added to conventional risk factors.ConclusionsThe current study suggests that a higher thigh muscle fat infiltration is associated with an increased risk of developing vascular events among Korean adults.
Project description:We aimed to analyse the mechanical properties of skinned single muscle fibres derived from the vastus lateralis (VL) muscle in relation to those of the whole intact thigh muscle and to compare any difference between young and older adults. Sixteen young men (29.25 ± 4.65 years), 11 older men (71.45 ± 2.94 years), 11 young women (29.64 ± 4.88 years), and 7 older women (67.29 ± 1.70 years) were recruited. In vivo analyses were performed for mechanical properties such as isokinetic performance, isometric torque, and power. Specific force and maximum shortening velocity (Vo) were measured with single muscle fibres. Sex difference showed greater impact on the functional properties of both the whole muscle (p < 0.01) and single muscle fibres than aging (p < 0.05). Sex difference, rather than aging, yielded more remarkable differences in gross mechanical properties in the single muscle fibre study in which significant differences between young men and young women were found only in the cross-sectional area and Vo (p < 0.05). Age and sex differences reflect the mechanical properties of both single muscle fibres and whole thigh muscle, with the whole muscle yielding more prominent functional properties.
Project description:Muscle mass is particularly relevant to follow during aging, owing to its link with physical performance and autonomy. The objectives of this work were to assess muscle volume (MV) and intramuscular fat (IMF) for all the muscles of the thigh in a large population of young and elderly healthy individuals using magnetic resonance imaging (MRI) to test the effect of gender and age on MV and IMF and to determine the best representative slice for the estimation of MV and IMF. The study enrolled 105 healthy young (range 20-30 years) and older (range 70-80 years) subjects. MRI scans were acquired along the femur length using a three-dimension three-point Dixon proton density-weighted gradient echo sequence. MV and IMF were estimated from all the slices. The effects of age and gender on MV and IMF were assessed. Predictive equations for MV and IMF were established using a single slice at various femur levels for each muscle in order to reduce the analysis process. MV was decreased with aging in both genders, particularly in the quadriceps femoris. IMF was largely increased with aging in men and, to a lesser extent, in women. Percentages of MV decrease and IMF increase with aging varied according to the muscle. Predictive equations to predict MV and IMF from single slices are provided and were validated. This study is the first one to provide muscle volume and intramuscular fat infiltration in all the muscles of the thigh in a large population of young and elderly healthy subjects.
Project description:Study designCross-sectional study.ObjectivesA spinal cord injury (SCI) can compromise the ability to maintain sufficient balance control during activities in an upraised position. The objective of the study was to explore the relationship between balance control and muscle strength and muscle activation in the lower extremities in persons with incomplete SCI (iSCI).SettingSunnaas Rehabilitation Hospital, Norway.MethodsThirteen men and two women with iSCI and 15 healthy, matched controls were included. Performance of the Berg Balance Scale (BBS) short version (7 items) was used to indicate balance control. Maximal voluntary contraction (MVC) was performed to measure isometric muscle strength in thigh muscles (knee extension/flexion), while surface electromyography (EMG) was measured from M. Vastus Lateralis and M. Biceps Femoris. The relative activation of each muscle during each of the BBS tasks was reported as the percentage of the maximal activation during the MVC (%EMGmax).ResultsThe iSCI participants had a significantly lower BBS sum score and up to 40% lower muscle strength in knee- flexion and extension compared to the matched healthy controls. They also exhibited a significantly higher %EMGmax, i.e. a higher muscle activation, during most of the balance tests. Univariate regression analysis revealed a significant association between balance control and mean values of %EMGmax in Biceps Femoris, averaged over the seven BBS tests.ConclusionsThe participants with iSCI had poorer balance control, reduced thigh muscle strength and a higher relative muscle activation in their thigh muscles, during balance-demanding activities.
Project description:BackgroundThe relationship of specific body composition in the thighs and brain amyloid-beta (Aβ) deposition remained unclear, although there were growing evidence that higher muscle and fat mass in thighs had a protective effect against cardiometabolic syndromes. To determine whether muscle mass and fat mass in the thighs affected amyloid-beta (Aβ) positivity differently in relation to gender, we investigated the association of muscle mass and fat mass with Aβ positivity using positron emission tomography (PET) in individuals without dementia.MethodsWe recruited 240 participants (134 [55.8%] males, 106 [44.2%] females) without dementia ≥45 years of age who underwent Aβ PET, bioelectrical impedance analysis (BIA) and dual-energy X-ray absorptiometry (DEXA) scans of the hip in the health promotion center at Samsung Medical Center in Seoul, Korea. Lower extremity skeletal muscle mass index (LASMI) was measured using BIA, and gluteofemoral fat percentage (GFFP) was estimated using DEXA scans of the hip. We investigated the associations of LASMI and GFFP with Aβ positivity using logistic regression analyses after controlling for age, APOE4 genotype, and cognitive stage.ResultsHigher muscle mass in the thighs, measured as LASMI (odds ratio [OR]=0.27, 95% confidence interval [CI] 0.08 to 0.84, p=0.031) was associated with a lesser risk of Aβ positivity in only females. Higher fat mass in the thighs, measured as GFFP (OR=0.84, 95% CI 0.73 to 0.95, p=0.008) was associated with a lesser risk of Aβ positivity in only males. However, the association between LAMSI (p for interaction= 0.810), GFFP (p for interaction= 0.075) and Aβ positivity did not significantly differ by gender. Furthermore, LAMSI only negatively correlated with centiloid (CL) values in females (r=-0.205, p=0.037), and GFFP only negatively correlated with CL values only in males (r=-0.253, p=0.004).ConclusionsOur findings highlight the importance of recognizing that gender differences exist with respect to the specific body composition to potentially protect against Aβ deposition. Therefore, our results may help in designing gender-specific strategies for controlling body composition to prevent Aβ deposition.
Project description:Determining the effect of ageing on thigh muscle stiffness using magnetic resonance elastography (MRE) and investigate whether fat fraction and muscle cross-sectional area (CSA) are related to stiffness. Six healthy older adults in their eighth and ninth decade and eight healthy young men were recruited and underwent a 3 T MRI protocol including MRE and Dixon fat fraction imaging. Muscle stiffness, fat fraction and muscle CSA were calculated in ROIs corresponding to the four quadriceps muscles (i.e. vastus lateralis (VL), vastus medialis (VM), vastus intermedius (VI), rectus femoris (RF)), combined quadriceps, combined hamstrings and adductors and whole thigh. Muscle stiffness was significantly reduced (p?<?0.05) in the older group in all measured ROIs except the VI (p?=?0.573) and RF (p?=?0.081). Similarly, mean fat fraction was significantly increased (p?<?0.05) in the older group over all ROIs with the exception of the VI (p?=?0.059) and VL muscle groups (p?=?0.142). Muscle CSA was significantly reduced in older participants in the VM (p?=?0.003) and the combined quadriceps (p?=?0.001), hamstrings and adductors (p?=?0.008) and whole thigh (p?=?0.003). Over the whole thigh, stiffness was significantly negatively correlated with fat fraction (r?=?-?0.560, p?=?0.037) and positively correlated with CSA (r?=?0.749, p?=?0.002). Stepwise regression analysis revealed that age was the most significant predictor of muscle stiffness (p?=?0.001). These results suggest that muscle stiffness is significantly decreased in healthy older adults. Muscle fat fraction and muscle CSA are also significantly changed in older adults; however, age is the most significant predictor of muscle stiffness.
Project description:We examined the six small lateral rotators of the hip joint, which is one of the most flexible joints and allows kinematically complex motions of the hindlimb, to elucidate the functional differentiation among these muscles and to test the hypothesis that species-specific characteristics in hindlimb use during locomotion are reflected in the muscle spindle density and in other parameters of the deep small hip joint rotators. For these purposes, we estimated the number of muscle spindles of the superior gemellus muscle (SG), inferior gemellus muscle, quadratus femoris muscle, obturator internus muscle (OI), obturator externus muscle, and piriformis muscle in three Japanese macaques and a gibbon, using 30-µm-thick serial sections throughout each muscle length after azan staining. The numbers of muscle spindles per 10,000 muscle fibers were determined to compare inter-muscle variation. The spindle density was highest in the SG and lowest in the OI in the Japanese macaques, suggesting that the SG, which is attached to the tendon of the OI, functions as a kinesiological monitor of the OI. On the other hand, SG the was missing in the gibbon, and the OI in the gibbon contained more spindles than that in the Japanese macaques. This suggests that the SG and the OI fused into one muscle in the gibbon. We postulate that the relative importance of the deep small hip rotator muscles differs between the Japanese macaques and gibbon and that the gibbon's muscles are less differentiated in terms of the spindle density, probably because this brachiating species uses its hindlimbs less frequently.