Thigh Muscle Volume Research Articles

Musculoskeletal Effects of 2 Functional Electrical Stimulation Cycling Paradigms Conducted at Different Cadences for People With Spinal Cord Injury: A Pilot Study

ObjectiveTo compare the musculoskeletal effects of low cadence cycling with functional electrical stimulation (FES) with high cadence FES cycling for people with spinal cord injury (SCI). DesignRandomized pre-post design. SettingOutpatient rehabilitation clinic. ParticipantsParticipants (N=17; 14 men, 3 women; age range, 22–67y) with C4-T6 motor complete chronic SCI were randomized to low cadence cycling (n=9) or high cadence cycling (n=8). InterventionsLow cadence cycling at 20 revolutions per minute (RPM) and high cadence cycling at 50 RPM 3 times per week for 6 months. Cycling torque (resistance per pedal rotation) increased if targeted cycling cadence was maintained. Main Outcome MeasuresDual-energy x-ray absorptiometry was used to assess distal femur areal bone mineral density, magnetic resonance imaging was used to assess to assess trabecular bone microarchitecture and cortical bone macroarchitecture and thigh muscle volume, and biochemical markers were used to assess bone turnover. It was hypothesized that subjects using low cadence cycling would cycle with greater torque and therefore show greater musculoskeletal improvements than subjects using high cadence cycling. ResultsA total of 15 participants completed the study. Low cadence cycling obtained a maximal average torque of 2.9±2.8Nm, and high cadence cycling obtained a maximal average torque of 0.8±0.2Nm. Low cadence cycling showed greater decreases in bone-specific alkaline phosphatase, indicating less bone formation (15.5% decrease for low cadence cycling, 10.7% increase for high cadence cycling). N-telopeptide decreased 34% following low cadence cycling, indicating decreased resorption. Both groups increased muscle volume (low cadence cycling by 19%, high cadence cycling by 10%). Low cadence cycling resulted in a nonsignificant 7% increase in apparent trabecular number (P=.08) and 6% decrease in apparent trabecular separation (P=.08) in the distal femur, whereas high cadence cycling resulted in a nonsignificant (P>.3) 2% decrease and 3% increase, respectively. ConclusionsThis study suggests that the greater torque achieved with low cadence cycling may result in improved bone health because of decreased bone turnover and improved trabecular bone microarchitecture. Longer-term outcome studies are warranted to identify the effect on fracture risk.

Effects of In-Season Short-term Plyometric Training Program on Sprint and Jump Performance of Young Male Track Athletes.

We studied the effect of supplementing normal in-season training by a 10-week lower limb plyometric training program (hurdle and depth jumping), examining measures of competitive potential (peak power output [PP], sprint running velocity, squat jump [SJ], countermovement jump [CMJ], drop jump [DJ], and lower limb muscle volume). The subjects (27 male track athletes, aged 11.9 ± 1.0 years; body mass: 39.1 ± 6.1 kg; height: 1.56 ± 0.02 m; body fat: 12.8 ± 4.4%) were randomly assigned between a control (normal training) group (C; n = 13) and an experimental group (E; n = 14) who also performed plyometric training 3 times per week. A force-velocity ergometer test determined PP and SJ, and an Optojump apparatus evaluated CMJ height and DJ (height and power). A multiple-5-bound test assessed horizontal jumping, and video-camera analyses over a 40-m sprint yielded velocities for the first step (VS), the first 5 m (V5m), and between 35 and 40 m (Vmax). Leg muscle volume was estimated anthropometrically. Experimental group showed gains relative to C in SJ height (p < 0.001); CMJ height (p < 0.01); DJ height and power relative to body mass (p < 0.01 for both); and all sprint velocities (p < 0.01 for VS and V(5m, p) ≤ 0.05 for Vmax). There was also a significant increase (p < 0.01) in thigh muscle volume, but leg muscle volume, thigh cross-sectional area, and PP remained unchanged. We conclude that adding plyometric training improved important components of athletic performance relative to standard in-season training in young runners.

Fish oil–derived n−3 PUFA therapy increases muscle mass and function in healthy older adults

Age-associated declines in muscle mass and function are major risk factors for an impaired ability to carry out activities of daily living, falls, prolonged recovery time after hospitalization, and mortality in older adults. New strategies that can slow the age-related loss of muscle mass and function are needed to help older adults maintain adequate performance status to reduce these risks and maintain independence. We evaluated the efficacy of fish oil-derived n-3 (ω-3) PUFA therapy to slow the age-associated loss of muscle mass and function. Sixty healthy 60-85-y-old men and women were randomly assigned to receive n-3 PUFA (n = 40) or corn oil (n = 20) therapy for 6 mo. Thigh muscle volume, handgrip strength, one-repetition maximum (1-RM) lower- and upper-body strength, and average power during isokinetic leg exercises were evaluated before and after treatment. Forty-four subjects completed the study [29 subjects (73%) in the n-3 PUFA group; 15 subjects (75%) in the control group]. Compared with the control group, 6 mo of n-3 PUFA therapy increased thigh muscle volume (3.6%; 95% CI: 0.2%, 7.0%), handgrip strength (2.3 kg; 95% CI: 0.8, 3.7 kg), and 1-RM muscle strength (4.0%; 95% CI: 0.8%, 7.3%) (all P < 0.05) and tended to increase average isokinetic power (5.6%; 95% CI: -0.6%, 11.7%; P = 0.075). Fish oil-derived n-3 PUFA therapy slows the normal decline in muscle mass and function in older adults and should be considered a therapeutic approach for preventing sarcopenia and maintaining physical independence in older adults. This study was registered at clinicaltrials.gov as NCT01308957.

Allometric Scaling Is The Best Method For Normalizing Maximal Oxygen Uptake In Young Soccer Players

Maximum oxygen uptake (VO2max) has been considered an important marker of health and sports performance. Traditionally VO2max is normalized by body mass (mL.kg-1.min-1), however this approach leads an overestimation of the performance in lighter individuals and an underestimation in those heavier. Determine what method is the most appropriate to normalize VO2max is important to allow comparisons between individuals with different body size. PURPOSE: To investigate the best method of normalization for VO2max in young athletes heterogeneous in body size using separate scaling variables and allometric modeling. METHODS: Seventy-nine young soccer players (age = 15.3±1.5 years, body mass = 68±10 kg, height = 175±8 cm and VO2max = 4136±552 mL.min-1) participated in this study. Scaling variables were body mass, height, body mass index (BMI), interaction between body mass height, body surface area (BSA), rectus femoris cross-section area (CSA), thigh and leg muscle thickness (MT) and muscle volumes (MV) (thigh, leg, and lower limbs). Allometric model was adopted to examine the relationship between body size descriptor and VO2max (Y = aXbε). CSA, MT and MV were measured using ultrasonography and VO2max using a metabolic cart. The variables with a very large correlation with VO2max were considered for normalization. RESULTS: CSA, BMI and thigh and leg MT and MV were discarded as a moderate to large correlation with VO2max mL.min-1 (0.3 < r < 0.7) was found. Body mass, height, BSA, interaction body mass height, and lower limb MV showed a very large correlation (r > 0.7) with VO2max mL.min-1. After normalization by body mass (mL.kg-1.min-1), height (mL.m-1.min-1), BSA (mL.m-2.min-1), lower limbs MV (mL.mL-1.min-1) and interaction body mass height (mL.kgm-1.min-1) a significant correlation among scaling variables and normalized VO2max remained (0.3 < r < 0.8, p<0.05). The allometric scaling of body mass (mL.kg-0.79.min-1), height (mL.m-2.18.min-1), BSA (mL.m-2.37.min-1), lower limbs MV (mL.mL-0.43.min-1) and interaction body mass height (mL.kgm-0.63.min-1) were effective to adjust the effect of body size on VO2max, with no significant correlation among scaling variables and normalized VO2max (p>0.05). CONCLUSION: Allometric scaling is best method to normalize VO2max in young soccer players.

Muscle imaging data in late-onset Pompe disease reveal a correlation between the pre-existing degree of lipomatous muscle alterations and the efficacy of long-term enzyme replacement therapy

BackgroundLate-onset Pompe disease (LOPD) is a metabolic myopathy caused by mutations in GAA and characterized by proximal muscle weakness and respiratory insufficiency. There is evidence from clinical studies that enzyme replacement therapy (ERT) with human recombinant alpha-glucosidase improves motor performance and respiratory function in LOPD. ObjectiveWe analyzed quantitative muscle MRI data of lower limbs to evaluate the effects of long-term ERT on muscle parameters. MethodsThree symptomatic LOPD patients who received ERT for five years and four untreated presymptomatic LOPD patients were included in the study. T1-weighted MRI images were used to determine volumes of thigh and lower leg muscles. In addition, mean gray values of eight individual thigh muscles were calculated to assess the degree of lipomatous muscle alterations. ResultsWe detected a decrease in thigh muscle volume of 6.7% (p<0.001) and an increase in lower leg muscle volume of 8.2% (p=0.049) after five years of ERT. Analysis of individual thigh muscles revealed a positive correlation between the degree of lipomatous muscle alterations at baseline and the increase of gray values after five years of ERT (R2=0.68, p<0.001). Muscle imaging in presymptomatic patients showed in one case pronounced lipomatous alteration of the adductor magnus muscle and mild to moderate changes in further thigh muscles. ConclusionsThe results demonstrate that fatty muscle degeneration can occur before clinical manifestation of muscle weakness and suggest that mildly affected muscles may respond better to ERT treatment than severely involved muscles. If these findings can be validated by further studies, it should be discussed if muscle alterations detected by muscle MRI may be an objective sign of disease manifestation justifying an early start of ERT in clinically asymptomatic patients in order to improve the long-term outcome.

Effect of protein source during weight loss on body composition, cardiometabolic risk and physical performance in abdominally obese, older adults: a pilot feeding study.

The purpose of this pilot study was to begin to examine the effect of dietary protein source (soy protein versus non-soy protein) during weight loss on body composition, and cardiometabolic and functional decline risk factors in older, abdominally obese adults. Two-arm, single-blind, randomized, controlled trial. Wake Forest School of Medicine, Winston-Salem NC 27157, USA. 25 older (68.4±5.5 years, 88% female), abdominally obese (BMI: 35.1±4.3 kg/m2; WC: 101.4±13.1 cm) men and women were randomized to participate in the study. A 12-week weight loss intervention, with participants randomized to consume soy protein-based meal replacements (S; n=12) or non-soy protein-based meal replacements (NS; n=12), in addition to prepared meals, and all participants targeted to receive an individualized caloric deficit of 500 kcal/day. Body weight and composition (assessed via DXA and CT), conventional biomarkers of cardiometabolic risk, and physical performance measures were assessed pre- and post-intervention. Additional endpoints of feasibility (accrual, participation, retention, compliance, and safety) are reported. A total of 24 participants (87% female) completed the study (96% retention) and lost an average of 7.8±3.0 kg over the 12-week period, with no difference seen between groups (p=0.83). Although nearly all measures of global and regional body composition were significantly reduced following the 12-week intervention, differences were not observed between groups. Among cardiometabolic risk factors and physical performance measures, only diastolic blood pressure was significantly lower in the NS group compared to the S group (66.7±2.7 mmHg vs 73.5±2.7 mmHg, respectively; p=0.04). Interestingly, in groups combined, despite significant reductions in body weight and lean mass, no significant changes in 400-meter walk time (+5.3±43.4 s), short physical performance battery score (+0.1±1.0), grip strength (-0.3±3.2 kg), or relative knee extensor strength (-0.0±0.0 N/m/cm3 thigh muscle volume) were observed. Data presented here suggest that a 12-week weight loss intervention, which incorporates S and NS meal replacement products, is associated with clinically significant weight loss and improvements in several parameters of cardiometabolic risk and unchanged physical function and strength. RESULTS do not differ by protein source and suggest that soy protein is at least as good as other protein sources for weight loss during low-calorie dietary interventions in older adults.

Pannon breeding program in rabbit at Kaposvár University

In this study, the rabbit breeding programme conducted at the Kaposvar University is extensively discussed. Population history and recorded traits, creation of the different synthetic lines, evolution of their selection criteria, stimation of the genetic parameters and genetic trends are the main elements described. The programme (Pannon rabbit breeding programme) is operated with 1 maternal line and 2 paternal lines. At present the maternal line (Pannon Ka) is selected for number of kits born alive, while the 2 paternal lines are pre-selected for litter weight (Pannon White) and average daily gain (Pannon terminal line), respectively, then they are both selected for thigh muscle volume (based on computer tomography (CT) measurements). All these traits are evaluated by BLUP methodology. According to the genetic parameter estimations, the heritability of the reproductive traits (litter size and litter weight) was low (0.05-0.17 and 0.08-0.17). When the litter size component traits were extended with dominance effects, the magnitude of the dominance components varied between 0.05 and 0.08. Average daily gain and thigh muscle volume were moderately heritable (0.21-0.27 and 0.19-0.25), while heritability estimates of the carcass traits (dressing out percentage and hind part ratio) were high (0.47 and 0.59). Computer tomography based traits showed favourable high genetic correlations with the carcass traits (dressing out percentage: 0.45-0.47 and hind part ratio: 0.59). On the contrary, strong negative correlation was estimated between thigh muscle volume and litter weight (–0.37 and –0.70). The selection responses obtained for all analysed traits were within the range published by the relevant literature. The success of the CT-based selection for improving meat production was justified by different methods (crossing experiment, divergent selection, estimated genetic trends). In addition to the slow increase in the inbreeding level of the Pannon White breed, it also proves the effectiveness of the circular mating scheme used in all three rabbit breeds in the programme.

Treatment of sporadic inclusion body myositis with bimagrumab.

To study activin signaling and its blockade in sporadic inclusion body myositis (sIBM) through translational studies and a randomized controlled trial. We measured transforming growth factor β signaling by SMAD2/3 phosphorylation in muscle biopsies of 50 patients with neuromuscular disease (17 with sIBM). We tested inhibition of activin receptors IIA and IIB (ActRII) in 14 patients with sIBM using one dose of bimagrumab (n = 11) or placebo (n = 3). The primary outcome was the change in right thigh muscle volume by MRI at 8 weeks. Lean body mass, strength, and function were secondary outcomes. Twelve of the patients (10 bimagrumab, 2 placebo) participated in a subsequent 16-week observation phase. Muscle SMAD2/3 phosphorylation was higher in sIBM than in other muscle diseases studied (p = 0.003). Eight weeks after dosing, the bimagrumab-treated patients increased thigh muscle volume (right leg +6.5% compared with placebo, p = 0.024; left leg +7.6%, p = 0.009) and lean body mass (+5.7% compared with placebo, p = 0.014). Subsequently, bimagrumab-treated patients had improved 6-minute walking distance, which peaked at 16 weeks (+14.6%, p = 0.008) compared with placebo. There were no serious adverse events; the main adverse events with bimagrumab were mild acne and transient involuntary muscle contractions. Transforming growth factor β superfamily signaling, at least through ActRII, is implicated in the pathophysiology of sIBM. Inhibition of ActRII increased muscle mass and function in this pilot trial, offering a potential novel treatment of sIBM. This study provides Class I evidence that for patients with inclusion body myositis, bimagrumab increases thigh muscle volume at 8 weeks.

Bone strength is related to muscle volume in ambulant individuals with bilateral spastic cerebral palsy

ObjectiveThe aim of this study is to investigate how bone strength in the distal femur and proximal tibia are related to local muscle volume in ambulant individuals with bilateral spastic cerebral palsy (CP). MethodsTwenty-seven participants with CP (mean age: 14.6±2.9years; Gross Motor Function Classification System (GMFCS) levels I-III) and twenty-two typically developing (TD) peers (mean age: 16.7±3.3years) took part in this study. Periosteal and medullary diameter in the distal femur and cortical bone cross-sectional area (CSA) and thickness (CT) in the distal femur and proximal tibia were measured along with nine lower limb muscle volumes using MRI. Additionally, the polar section modulus (Zp) and buckling ratio (BR) were calculated to estimate bone bending strength and compressional bone stability respectively in the distal femur. The relationships of all measured parameters with muscle volume, height, age, body mass, gender, and subject group were investigated using a generalized linear model (GZLM). ResultsIn the distal femur, Zp was significantly positively related to thigh muscle volume (p=0.007), and height (p=0.026) but not significantly related to subject group (p=0.076) or body mass (p=0.098). BR was not significantly different between groups and was not related to any of the variables tested. Cortical bone CSA was significantly lower in the CP group at both the distal femur (p=0.002) and proximal tibia (p=0.009). It was also positively associated with thigh muscle volume (p<0.001) at the distal femur, and with subject height (p=0.005) at the proximal tibia. ConclusionsBending and compressional strength of the femur, estimated from Zp and cortical bone CSA respectively, is associated with reduced thigh muscle volume. Increasing muscle volume by strength training may have a positive effect on bone mechanics in individuals with CP.

Effects of 8-Week In-season Plyometric Training on Upper and Lower Limb Performance of Elite Adolescent Handball Players

We hypothesized that replacement of a part of the normal in-season regimen of top-level adolescent handball players by an 8-week biweekly course of lower and upper limb plyometric training would enhance characteristics important to competition, including peak power output (Wpeak), jump performance, muscle volume, and ball throwing velocity. Study participants (23 men, age: 17.4 ± 0.5 years, body mass: 79.9 ± 11.5 kg, height: 1.79 ± 6.19 m, body fat: 13.8 ± 2.1%) were randomly assigned between controls (C; n = 11) and an experimental group (E, n = 12). Measures preintervention and postintervention included force-velocity ergometer tests for upper (Wupper peak) and lower limbs (Wlower peak), force platform determinations of squat jump (SJ) and countermovement jump (CMJ) characteristics (jump height, maximal force, initial velocity, and average power), video filming of sprint velocities (first step [V1S], first 5 m [V5m], and 25-30 m [Vmax]), and anthropometric estimates of leg muscle volume. E showed gains relative to C in Wupper peak and Wlower peak (p < 0.01 and p < 0.001), SJ (height p < 0.01; force p ≤ 0.05), CMJ (height p < 0.01; force p < 0.01 and relative power p ≤ 0.05), and sprint velocities (p < 0.001 for V1S, V5m, and Vmax). E also showed increases in leg and thigh muscle volumes (p < 0.001), but arm muscle volumes did not differ from control. We conclude that introduction of biweekly plyometric training into the standard regimen improved components important to handball performance, particularly explosive actions, such as sprinting, jumping, and ball throwing velocity.

Skeletal muscle fat accumulation and increased fatty acid saturation are related to worsening glucose control in older adults (133.8)

Increased inter‐muscular adipose tissue (IMAT) content and intra‐myocellular lipid (IMCL) fatty acid saturation (FAS) are implicated in insulin resistance (IR), but potential relationships require further investigation because of limited data. This study examined the associations between IMAT content, IMCL FAS, and fasting plasma glucose concentrations in 10 men and women, age range 65‐76 y, plasma glucose 101±11 mg/dL (range 87‐114 mg/dL). Thigh muscle and adipose tissue volumes (magnetic resonance imaging) and the FAS of vastus lateralis IMCL (from muscle biopsies using Coherent Anti‐scattering Raman Spectroscopy and Spontaneous Raman Spectroscopy) were quantified. IMAT volume, standardized with respect to muscle tissue volume (ratio 0.10±0.02), was positively correlated with the ratio of saturated to unsaturated fatty acids in IMCL (r=0.709, p=0.02). IMAT volume and IMCL FAS were both positively associated with plasma glucose concentration (β=300.6, p=0.02, and β=105.4, p=0.02, respectively). These results suggest that inter‐muscular fat accumulation and increased myocellular fatty acid saturation are related to each other and both may contribute to worsening glucose control.Grant Funding Source: Supported by NIH UL1 TR000006, Purdue Ingest Behav Res Ctr, Amer Egg Board, Dairy Res Inst

Passive leg movement‐induced hyperaemia with a spinal cord lesion: evidence of preserved vascular function

A spinal cord injury (SCI) clearly results in greater cardiovascular risk; however, accompanying changes in peripheral vascular structure below the lesion mean that the real impact of a SCI on vascular function is unclear. Therefore, utilizing passive leg movement-induced (PLM) hyperaemia, an index of nitric oxide (NO)-dependent vascular function and the central hemodynamic response to this intervention, we studied eight individuals with a SCI and eight age-matched controls (CTRL). Specifically, we assessed heart rate (HR), stroke volume (SV), cardiac output (CO), mean arterial pressure (MAP), leg blood flow (LBF) and thigh composition. In CTRL, passive movement transiently decreased MAP and increased HR and CO from baseline by 2.5±1mmHg, 7±2bpm and 0.5±0.1Lmin(-1) respectively. In SCI, HR and CO responses were unidentifiable. LBF increased to a greater extent in CTRL (515±41∆mLmin(-1)) compared with SCI, (126±25∆mLmin(-1)) (P<0.05). There was a strong relationship between ∆LBF and thigh muscle volume (r=0.95). After normalizing ∆LBF for this strong relationship (∆LBF/muscle volume), there was evidence of preserved vascular function in SCI (CTRL: 120±9; SCI 104±11mLmin(-1)L(-1)). A comparison of ∆LBF in the passively moved and stationary leg, to partition the contribution of the blood flow response, implied that 35% of the hyperaemia resulted from cardioacceleration in the CTRL, whereas all the hyperaemia appeared peripheral in origin in the SCI. Thus, utilizing PLM-induced hyperaemia as marker of vascular function, it is evident that peripheral vascular impairment is not an obligatory accompaniment to a SCI.

Genetic parameters, genetic trends and inbreeding depression of growth and carcass traits in Pannon terminal line rabbits

Abstract. Genetic parameters, inbreeding depression and genetic trends were estimated for average daily gain between the ages of 5-10 weeks and thigh muscle volume (measured in vivo with computerized tomography) in a group of 22 098 Pannon terminal line rabbits born between 2006 and 2011 and reared in 3 396 litters. The data sets were analysed with bi-variate animal models taking pedigree completeness (complete generation equivalent) into account. By 2011, all rabbits were inbred and the average inbreeding coefficient and complete generation equivalent of the population were 7.69 % and 11.89 %, respectively. Estimated heritability was moderate both for average daily gain (0.23±0.02) and thigh muscle volume (0.25±0.03). Litter effects were low for both traits (0.16±0.00 and 0.09±0.01 respectively). The genetic correlation coefficient estimate between average daily gain and thigh muscle volume was also low (0.02±0.08). Significant inbreeding depression (per 10 % inbreeding) was only detected for average daily gain (0.57 g/d). The estimated annual selection response was substantial both for average daily gain and thigh muscle volume (1.49 g/d and 5.84 cm3, respectively), proving the efficiency of the breeding programme.

Thigh muscle volume in relation to age, sex and femur volume

Secular changes and intra-individual differences in body shape and size can confound cross-sectional studies of muscle ageing. Normalising muscle mass to height squared is often suggested as a solution for this. We hypothesised that normalisation of muscle volume to femur volume may be a better way of determining the extent of muscle lost with ageing (sarcopenia). Thigh and femur muscle volumes were measured from serial magnetic resonance imaging sections in 20 recreationally active young men (mean age 22.4 years), 25 older men (72.3 years), 18 young women (22.1 years) and 28 older women (72.0 years). There were no age-related differences in femur volume. The relationship between thigh muscle volume and femur volume (R (2) = 0.76; exponent of 1.12; P < 0.01) was stronger than that with height (R (2) = 0.49; exponent of 3.86; P < 0.01) in young participants. For young subjects, the mean muscle/bone ratios were 16.0 and 14.6 for men and women, respectively. For older men and women, the mean ratios were 11.6 and 11.5, respectively. The Z score for the thigh muscle/bone volume ratio relative to young subjects was -2.2 ± 0.7 for older men and -1.4 ± 0.8 for older women. The extent of sarcopenia judged by the muscle/bone ratio was approximately twice that determined when normalising to height squared. These data suggest that the muscle/bone ratio captures the intra-individual loss of muscle mass during ageing, and that the age-related loss of muscle mass may be underestimated when normalised to height squared. The quadriceps seems relatively more affected by ageing than other thigh muscles.

Changes in thigh muscle volume predict bone mineral density response to lifestyle therapy in frail, obese older adults

We studied the relationships among strength, muscle mass, and bone mineral density (BMD) with lifestyle change. Lifestyle therapy consisted of exercise, diet, and diet plus exercise. Diet was by caloric restriction to induce and maintain a weight loss of 10 % from baseline body weight. Exercise attenuated weight loss-induced muscle and bone losses. Exercise improved strength despite muscle loss in patients on diet and exercise. Changes in strength did not correlate with changes in BMD. However, changes in thigh muscle volume correlated with, and predicted changes in hip BMD. Losses of hip BMD and lean body mass are major complications of lifestyle therapy in frail, obese older adults; however, the contribution of mechanical strain loss from muscle loss is poorly defined. We determined the effect of changes in thigh muscle volume and muscle strength on BMD in frail, obese older adults undergoing lifestyle therapy aimed at intentional weight loss with or without exercise. One hundred seven obese older adults were randomized to control, diet, exercise, and diet-exercise groups for 1 year. Thigh muscle volume was measured by magnetic resonance imaging, BMD by DXA, knee strength by dynamometry, total strength by one-repetition maximum (1-RM), and bone markers by immunoassay. Thigh muscle volume decreased in the diet group (-6.2 ± 4.8 %) and increased in the exercise group (2.7 ± 3.1 %), while it was not significantly different from the control in the diet-exercise group. Changes in hip BMD followed similar pattern as those in thigh muscle volume. Knee extension and flexion increased in the exercise group (23 ± 20 %; 25 ± 19 %) and diet-exercise group (20 ± 19 %; 20.6 ± 27 %) but were unchanged in the control and diet groups. Changes in thigh muscle volume correlated with changes in hip BMD (r = 0.55, P = <0.001) and were an independent predictor of changes in hip BMD (β = 0.12, P = 0.03) in the multiple regression analyses after accounting for demographic factors and changes in weight and physical activity. There were no correlations between BMD changes and knee strength, 1-RM, and sclerostin changes. Changes in thigh muscle volume predict hip BMD changes in obese older patients undergoing lifestyle therapy. The effect of exercise in attenuating thigh muscle loss when added to diet may in part account for the reduction in weight loss-induced bone loss in the diet-exercise group.

Strength Training for Arthritis Trial (START): design and rationale

BackgroundMuscle loss and fat gain contribute to the disability, pain, and morbidity associated with knee osteoarthritis (OA), and thigh muscle weakness is an independent and modifiable risk factor for it. However, while all published treatment guidelines recommend muscle strengthening exercise to combat loss of muscle mass and strength in knee OA patients, previous strength training studies either used intensities or loads below recommended levels for healthy adults or were generally short, lasting only 6 to 24 weeks. The efficacy of high-intensity strength training in improving OA symptoms, slowing progression, and affecting the underlying mechanisms has not been examined due to the unsubstantiated belief that it might exacerbate symptoms. We hypothesize that in addition to short-term clinical benefits, combining greater duration with high-intensity strength training will alter thigh composition sufficiently to attain long-term reductions in knee-joint forces, lower pain levels, decrease inflammatory cytokines, and slow OA progression.Methods/DesignThis is an assessor-blind, randomized controlled trial. The study population consists of 372 older (age ≥ 55 yrs) ambulatory, community-dwelling persons with: (1) mild-to-moderate medial tibiofemoral OA (Kellgren-Lawrence (KL) = 2 or 3); (2) knee neutral or varus aligned knee ( -2° valgus ≤ angle ≤ 10° varus); (3) 20 kg.m-2 ≥ BMI ≤ 45 kg.m-2; and (3) no participation in a formal strength-training program for more than 30 minutes per week within the past 6 months. Participants are randomized to one of 3 groups: high-intensity strength training (75-90% 1Repetition Maximum (1RM)); low-intensity strength training (30-40%1RM); or healthy living education. The primary clinical aim is to compare the interventions’ effects on knee pain, and the primary mechanistic aim is to compare their effects on knee-joint compressive forces during walking, a mechanism that affects the OA disease pathway. Secondary aims will compare the interventions’ effects on additional clinical measures of disease severity (e.g., function, mobility); disease progression measured by x-ray; thigh muscle and fat volume, measured by computed tomography (CT); components of thigh muscle function, including hip abductor strength and quadriceps strength, and power; additional measures of knee-joint loading; inflammatory and OA biomarkers; and health-related quality of life.DiscussionTest-retest reliability for the thigh CT scan was: total thigh volume, intra-class correlation coefficients (ICC) = 0.99; total fat volume, ICC = 0.99, and total muscle volume, ICC = 0.99. ICC for both isokinetic concentric knee flexion and extension strength was 0.93, and for hip-abductor concentric strength was 0.99. The reliability of our 1RM testing was: leg press, ICC = 0.95; leg curl, ICC = 0.99; and leg extension, ICC = 0.98. Results of this trial will provide critically needed guidance for clinicians in a variety of health professions who prescribe and oversee treatment and prevention of OA-related complications. Given the prevalence and impact of OA and the widespread availability of this intervention, assessing the efficacy of optimal strength training has the potential for immediate and vital clinical impact.Trial registrationClinicalTrials.gov, NCT01489462

Effect of Dietary Restriction and Exercise on Lower Extremity Tissue Compartments in Obese, Older Women: A Pilot Study

Accumulating evidence suggests that both dietary restriction and exercise (DR + E) should be incorporated in weight loss interventions to treat obese, older adults. However, more information is needed on the effects to lower extremity tissue composition-an important consideration for preserving mobility in older adults. Twenty-seven sedentary women (body mass index: 36.3±5.4kg/m(2); age: 63.6±5.6 yrs) were randomly assigned to 6 months of DR + E or a health education control group. Thigh and calf muscle, subcutaneous adipose tissue (SAT), and intermuscular adipose tissue (IMAT) size were determined using magnetic resonance imaging. Physical function was measured using a long-distance corridor walk and knee extension strength. Compared with control, DR + E significantly reduced body mass (-6.6±3.7kg vs control: -0.05±3.5kg; p < .01). Thigh and calf muscle volumes responded similarly between groups. Within the DR + E group, adipose tissue was reduced more in the thigh than in the calf (p < .04). Knee extension strength was unaltered by DR + E, but a trend toward increased walking speed was observed in the DR + E group (p = .09). Post hoc analyses showed that reductions in SAT and IMAT within the calf, but not the thigh, were associated with faster walking speed achieved with DR + E (SAT: r = -0.62; p = .01; IMAT: r = -0.62; p = .01). DR + E preserved lower extremity muscle size and function and reduced regional lower extremity adipose tissue. Although the magnitude of reduction in adipose tissue was greater in the thigh than the calf region, post hoc analyses demonstrated that reductions in calf SAT and IMAT were associated with positive adaptations in physical function.

Natural course of muscular involvement assessed by a new computed tomography method in Duchenne muscular dystrophy

AbstractAimEstablishing the natural course of muscular impairment in Duchenne muscular dystrophy (DMD) is essential for defining the effect of treatments in clinical trials. We retrospectively investigated the change of thigh muscle volume in DMD using new indices, muscle volume index (MVI) and %MVI.MethodsMVI is the estimated muscle volume contained within a given computed tomography (CT) slice and calculated using the CT histogram‐based procedure after correcting for a partial volume effect. %MVI is calculated by dividing the MVI by the entire volume of the region of interest. We applied this method to 49 retrospectively selected CT images from 21 patients with DMD, aged 6–13 years, at a relatively early stage.ResultsBoth MVI and %MVI were found to have a significant inverse correlation with the clinical disability stage. In most patients, the changes over time in MVI and %MVI could be regressed to the exponential function Y = Ae−rX. The rate constant of the approximation curve was 0.299 ± 0.072 for MVI, and 0.351 ± 0.088 for %MVI, respectively.ConclusionMVI and %MVI have proven useful for follow‐up assessments of skeletal muscle volume in patients with DMD. Our retrospective longitudinal study should provide a basis for evaluating therapeutic interventions in future clinical trials.

A single ascending‐dose study of muscle regulator ace‐031 in healthy volunteers

ACE-031 is a soluble form of activin receptor type IIB (ActRIIB). ACE-031 promotes muscle growth by binding to myostatin and other negative regulators of muscle mass. This double-blind, placebo-controlled study evaluated the safety, pharmacokinetics, and pharmacodynamics of ACE-031 in 48 healthy, postmenopausal women randomized to receive 1 dose of ACE-031 (0.02-3 mg/kg s.c.) or placebo (3:1). ACE-031 was generally well-tolerated. Adverse events included injection site erythema. Mean ACE-031 AUC(0-∞) and C(max) increased linearly with dose; mean T(½) was 10-15 days. Statistically significant increases in mean total body lean mass (3.3%; P = 0.03, by DXA) and thigh muscle volume (5.1%; P = 0.03, by MRI) were observed at day 29 in the 3 mg/kg group. Statistically significant changes in serum biomarkers suggest ACE-031 also improved bone and fat metabolism. Single-dose ACE-031 treatment was generally well-tolerated and resulted in increases in muscle mass in healthy postmenopausal women.

Strength training induces muscle hypertrophy and functional gains in black prostate cancer patients despite androgen deprivation therapy.

Androgen deprivation therapy (ADT) for prostate cancer (PCa) is associated with weakness, fatigue, sarcopenia, and reduced quality of life (QoL). Black men have a higher incidence and mortality from PCa than Caucasians. We hypothesized that despite ADT, strength training (ST) would increase muscle power and size, thereby improving body composition, physical function, fatigue levels, and QoL in older black men with PCa. Muscle mass, power, strength, endurance, physical function, fatigue perception, and QoL were measured in 17 black men with PCa on ADT before and after 12 weeks of ST. Within-group differences were determined using t tests and regression models. ST significantly increased total body muscle mass (2.7%), thigh muscle volume (6.4%), power (17%), and strength (28%). There were significant increases in functional performance (20%), muscle endurance (110%), and QoL scores (7%) and decreases in fatigue perception (38%). Improved muscle function was associated with higher functional performance (R (2) = 0.54) and lower fatigue perception (R (2) = 0.37), and both were associated with improved QoL (R (2) = 0.45), whereas fatigue perception tended to be associated with muscle endurance (R (2) = 0.37). ST elicits muscle hypertrophy even in the absence of testosterone and is effective in counteracting the adverse functional consequences of ADT in older black men with PCa. These improvements are associated with reduced fatigue perception, enhanced physical performance, and improved QoL. Thus, ST may be a safe and well-tolerated therapy to prevent the loss of muscle mass, strength, and power commonly observed during ADT.