MUSCLE STRENGTH AND MRI DETERMINED THIGH MUSCLE VOLUME IN YOUNG GIRLS980

This study examined the force-velocity and power-velocity relationships of the quadriceps muscles of children and adults. Measurements of muscle function were collected using the Con-Trex isokinetic dynamometer. Twenty adults and twenty children performed maximal effort knee extensions at nine different velocities. The mean force-velocity curves of children and adults revealed obvious differences between the groups. The curves remained different following corrections of torque for CSA and velocity for length. ANOVA revealed significant differences in the uncorrected values of power between the two groups. When power values were corrected for lean thigh muscle volume, no significant differences were found between the groups. These findings suggest that differences in muscle strength between children and adults are a function of muscle size and imply that muscle function remains relatively unchanged from childhood to early adulthood.

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Muscle strength, size and composition following 12 months of gender-affirming treatment in transgender individuals: retained advantage for the transwomen

10.1101/782557 ◽

2019 ◽

Author(s):

A Wiik ◽

TR Lundberg ◽

E Rullman ◽

DP Andersson ◽

M Holmberg ◽

...

Keyword(s):

Muscle Strength ◽

Muscle Mass ◽

Sex Hormones ◽

Hormone Replacement ◽

Knee Extensor ◽

Hormone Treatment ◽

Muscle Volume ◽

Thigh Muscle ◽

Flexor Muscle ◽

Cross Sectional

AbstractObjectivesThis study explored the effects of gender-affirming treatment, which includes inhibition of endogenous sex hormones and replacement with cross-sex hormones, on muscle function, size and composition in 11 transwomen (TW) and 12 transmen (TM).MethodsIsokinetic knee extensor and flexor muscle strength was assessed at baseline (T00), 4 weeks after gonadal suppression of endogenous hormones but before hormone replacement (T0), and 3 (T3) and 11 (T12) months after hormone replacement. In addition, at T00 and T12, we assessed lower-limb muscle volume using MRI, and cross-sectional area (CSA) and radiological density using CT.ResultsThigh muscle volume increased (15%) in TM, which was paralleled by increased quadriceps CSA (15%) and radiological density (6%). In TW, the corresponding parameters decreased by −5% (muscle volume) and −4% (CSA), while density remained unaltered. The TM increased strength over the assessment period, while the TW generally maintained or slightly increased in strength. Baseline muscle volume correlated highly with strength (R>0.75), yet the relative change in muscle volume and strength correlated only moderately (R=0.65 in TW and R=0.32 in TM). The absolute levels of muscle volume and knee extension strength after the intervention still favored the TW.ConclusionCross-sex hormone treatment markedly affects muscle strength, size and composition in transgender individuals. Despite the robust increases in muscle mass and strength in TM, the TW were still stronger and had more muscle mass following 12 months of treatment. These findings add new knowledge that could be relevant when evaluating transwomen’s eligibility to compete in the women’s category of athletic competitions.

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The effectiveness of blood-flow restricted resistance training in the musculoskeletal rehabilitation of patients with lower limb disorders: A systematic review and meta-analysis

Clinical Rehabilitation ◽

10.1177/02692155211003480 ◽

2021 ◽

pp. 026921552110034

Author(s):

Nico Nitzsche ◽

Alexander Stäuber ◽

Samuel Tiede ◽

Henry Schulz

Keyword(s):

Blood Flow ◽

Resistance Training ◽

Muscle Strength ◽

Lower Limb ◽

Meta Analysis ◽

Load Resistance ◽

Muscle Volume ◽

Low Load ◽

Study Characteristics ◽

Musculoskeletal Rehabilitation

Objective: This meta-analysis aimed to evaluate the effectiveness of low-load Resistance Training (RT) with or without Blood Flow Restriction (BFR) compared with conventional RT on muscle strength in open and closed kinetic chains, muscle volume and pain in individuals with orthopaedic impairments. Data sources: Searches were conducted in the PubMed, Web of Science, Scopus and Cochrane databases, including the reference lists of randomised controlled trials (RCT’s) up to January 2021. Review method: An independent reviewer extracted study characteristics, orthopaedic indications, exercise data and outcome measures. The primary outcome was muscle strength of the lower limb. Secondary outcomes were muscle volume and pain. Study quality and reporting was assessed using the TESTEX scale. Results: A total of 10 RCTs with 386 subjects (39.2 ± 17.1 years) were included in the analysis to compare low-load RT with BFR and high or low-load RT without BFR. The meta-analysis showed no significant superior effects of low-load resistance training with BFR regarding leg muscle strength in open and closed kinetic chains, muscle volume or pain compared with high or low-load RT without BFR in subjects with lower limb impairments. Conclusion: Low-load RT with BFR leads to changes in muscle strength, muscle volume and pain in musculoskeletal rehabilitation that are comparable to conventional RT. This appears to be independent of strength testing in open or closed kinetic chains.

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Association of Thigh Muscle Strength with Texture Features Based on Proton Density Fat Fraction Maps Derived from Chemical Shift Encoding-Based Water–Fat MRI

Diagnostics ◽

10.3390/diagnostics11020302 ◽

2021 ◽

Vol 11 (2) ◽

pp. 302

Author(s):

Michael Dieckmeyer ◽

Stephanie Inhuber ◽

Sarah Schläger ◽

Dominik Weidlich ◽

Muthu R. K. Mookiah ◽

...

Keyword(s):

Chemical Shift ◽

Muscle Strength ◽

Neuromuscular Disorders ◽

Texture Features ◽

Thigh Muscle ◽

Proton Density ◽

Proton Density Fat Fraction ◽

Thigh Muscles ◽

Fat Fraction ◽

Flexion Strength

Purpose: Based on conventional and quantitative magnetic resonance imaging (MRI), texture analysis (TA) has shown encouraging results as a biomarker for tissue structure. Chemical shift encoding-based water–fat MRI (CSE-MRI)-derived proton density fat fraction (PDFF) of thigh muscles has been associated with musculoskeletal, metabolic, and neuromuscular disorders and was demonstrated to predict muscle strength. The purpose of this study was to investigate PDFF-based TA of thigh muscles as a predictor of thigh muscle strength in comparison to mean PDFF. Methods: 30 healthy subjects (age = 30 ± 6 years; 15 females) underwent CSE-MRI of the lumbar spine at 3T, using a six-echo 3D spoiled gradient echo sequence. Quadriceps (EXT) and ischiocrural (FLEX) muscles were segmented to extract mean PDFF and texture features. Muscle flexion and extension strength were measured with an isokinetic dynamometer. Results: Of the eleven extracted texture features, Variance(global) showed the highest significant correlation with extension strength (p < 0.001, R2adj = 0.712), and Correlation showed the highest significant correlation with flexion strength (p = 0.016, R2adj = 0.658). Multivariate linear regression models identified Variance(global) and sex, but not PDFF, as significant predictors of extension strength (R2adj = 0.709; p < 0.001), while mean PDFF, sex, and BMI, but none of the texture features, were identified as significant predictors of flexion strength (R2adj = 0.674; p < 0.001). Conclusions: Prediction of quadriceps muscle strength can be improved beyond mean PDFF by means of TA, indicating the capability to quantify muscular fat infiltration patterns.

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Partial blood flow restriction without exercise to attenuate reduction in thigh muscle strength and trophism during immobilization: A meta-analysis

Physical Therapy in Sport ◽

10.1016/j.ptsp.2020.11.015 ◽

2021 ◽

Vol 47 ◽

pp. e4

Author(s):

Daniel Germano Maciel ◽

Mikhail Santos Cerqueira ◽

Jean Arthur Mendonça Barboza ◽

José Diego Sales do Nascimento ◽

Wouber Hérickson de Brito Vieira

Keyword(s):

Blood Flow ◽

Muscle Strength ◽

Meta Analysis ◽

Blood Flow Restriction ◽

Thigh Muscle ◽

Flow Restriction

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The Effects of Tourniquet Application in Total Knee Arthroplasty on the Recovery of Thigh Muscle Strength and Clinical Outcomes

The Journal of Knee Surgery ◽

10.1055/s-0040-1701454 ◽

2020 ◽

Cited By ~ 1

Author(s):

Omer Ayik ◽

Mehmet Demirel ◽

Fevzi Birisik ◽

Ali Ersen ◽

Halil I. Balci ◽

...

Keyword(s):

Total Knee Arthroplasty ◽

Muscle Strength ◽

Clinical Outcomes ◽

Knee Arthroplasty ◽

Peak Torque ◽

Thigh Muscle ◽

Controlled Study ◽

Total Work ◽

Isokinetic Muscle Strength ◽

Total Knee

AbstractThe present randomized controlled study aims to evaluate whether tourniquet application during total knee arthroplasty (TKA) has an effect on (1) thigh muscle strength (quadriceps and hamstring muscle strength) and (2) clinical outcomes (postoperative knee range of motion [ROM], postoperative pain level, and Knee Society Score [KSS]). The effects of tourniquet application during TKA were investigated in 65 patients randomly allocated to one of two groups: TKA with a tourniquet and TKA without a tourniquet. Patients in both groups were comparable in terms of the demographic and clinical data (p > 0.05 for age, number of patients, sex, radiographic gonarthrosis grade, American Society of Anesthesiologists [ASA] classification, and body mass index [BMI]). All patients in both groups were operated by the same surgeon using one type of prosthesis. Isokinetic muscle strength (peak torque and total work) of knee extensors (quadriceps) and flexors (hamstrings) was measured in Newton meters (Nm) using a CYBEX 350 isokinetic dynamometer (HUMAC/CYBEX 2009, Stoughton, MA). The combined KSS (knee score + function score), visual analog scale (VAS), and knee ROM were measured preoperatively and at 1 and 3 months postoperatively to evaluate clinical outcomes. There were no significant differences between the two groups in preoperative and postoperative values of isokinetic muscle strength (peak torque and total work) and aforementioned clinical outcomes (p < 0.05). The present study has shown that quadriceps strength and clinical outcomes were not improved in the early postoperative period (3 months) when a tourniquet was not used during TKA.

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Dynamic thigh muscle strength after auditory feedback training of body weight distribution in stroke patients

Physiotherapy Theory and Practice ◽

10.3109/09593989409047447 ◽

1994 ◽

Vol 10 (2) ◽

pp. 103-112 ◽

Cited By ~ 7

Author(s):

M. Engardt ◽

E. Knutsson

Keyword(s):

Body Weight ◽

Muscle Strength ◽

Weight Distribution ◽

Auditory Feedback ◽

Thigh Muscle ◽

Stroke Patients ◽

Feedback Training

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Power output and fatigue of human muscle in maximal cycling exercise

Journal of Applied Physiology ◽

10.1152/jappl.1983.55.1.218 ◽

1983 ◽

Vol 55 (1) ◽

pp. 218-224 ◽

Cited By ~ 76

Author(s):

N. McCartney ◽

G. J. Heigenhauser ◽

N. L. Jones

Keyword(s):

Power Output ◽

Fiber Type ◽

Average Power ◽

Lactate Concentration ◽

Peak Torque ◽

Muscle Volume ◽

Thigh Muscle ◽

Peak Power Output ◽

Maximal Power ◽

Maximal Power Output

We studied maximal torque-velocity relationships and fatigue during short-term maximal exercise on a constant velocity cycle ergometer in 13 healthy male subjects. Maximum torque showed an inverse linear relationship to crank velocity between 60 and 160 rpm, and a direct relationship to thigh muscle volume measured by computerized tomography. Peak torque per liter thigh muscle volume (PT, N X ml-1) was related to crank velocity (CV, rpm) in the following equation: PT = 61.7 - 0.234 CV (r = 0.99). Peak power output was a parabolic function of crank velocity in individual subjects, but maximal power output was achieved at varying crank velocities in different subjects. Fiber type distribution was measured in the two subjects showing the greatest differences and demonstrated that a high proportion of type II fibers may be one factor associated with a high crank velocity for maximal power output. The decline in average power during 30 s of maximal effort was least at 60 rpm (23.7 +/- 4.6% of initial maximal power) and greatest at 140 rpm (58.7 +/- 6.5%). At 60 rpm the decline in power over 30 s was inversely related to maximal oxygen uptake (ml X min-1 X kg-1) (r = 0.69). Total work performed and plasma lactate concentration 3 min after completion of 30-s maximum effort were similar for each crank velocity.

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Lower extremity muscle size and strength and aerobic capacity decrease with caloric restriction but not with exercise-induced weight loss

Journal of Applied Physiology ◽

10.1152/japplphysiol.00853.2006 ◽

2007 ◽

Vol 102 (2) ◽

pp. 634-640 ◽

Cited By ~ 111

Author(s):

Edward P. Weiss ◽

Susan B. Racette ◽

Dennis T. Villareal ◽

Luigi Fontana ◽

Karen Steger-May ◽

...

Keyword(s):

Weight Loss ◽

Caloric Restriction ◽

Aerobic Capacity ◽

Lean Mass ◽

Muscle Volume ◽

Muscle Size ◽

Thigh Muscle ◽

Physical Work ◽

Physical Work Capacity ◽

Exercise Induced

Caloric restriction (CR) results in fat loss; however, it may also result in loss of muscle and thereby reduce strength and aerobic capacity (V̇o2 max). These effects may not occur with exercise-induced weight loss (EX) because of the anabolic effects of exercise on heart and skeletal muscle. We tested the hypothesis that CR reduces muscle size and strength and V̇o2 max, whereas EX preserves or improves these parameters. Healthy 50- to 60-yr-old men and women (body mass index of 23.5–29.9 kg/m2) were studied before and after 12 mo of weight loss by CR ( n = 18) or EX ( n = 16). Lean mass was assessed by dual-energy X-ray absorptiometry, thigh muscle volume by MRI, isometric and isokinetic knee flexor strength by dynamometry, and treadmill V̇o2 max by indirect calorimetry. Both interventions caused significant decreases in body weight (CR: −10.7 ± 1.4%, EX: −9.5 ± 1.5%) and lean mass (CR: −3.5 ± 0.7%, EX: −2.2 ± 0.8%), with no significant differences between groups. Significant decreases in thigh muscle volume (−6.9 ± 0.8%) and composite knee flexion strength (−7.2 ± 3%) occurred in the CR group only. Absolute V̇o2 max decreased significantly in the CR group (−6.8 ± 2.3%), whereas the EX group had significant increases in both absolute (+15.5 ± 2.4%) and relative (+28.3 ± 3.0%) V̇o2 max. These data provide evidence that muscle mass and absolute physical work capacity decrease in response to 12 mo of CR but not in response to a similar weight loss induced by exercise. These findings suggest that, during EX, the body adapts to maintain or even enhance physical performance capacity.

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