scholarly journals Comparing Muscle Function of Children and Adults: Effects of Scaling for Muscle Size

2002 ◽  
Vol 14 (4) ◽  
pp. 369-376 ◽  
Author(s):  
Ursula Barrett ◽  
Drew Harrison
Keyword(s):  
Muscle Strength ◽  
Muscle Function ◽  
Early Adulthood ◽  
Muscle Volume ◽  
Muscle Size ◽  
Thigh Muscle ◽  
Isokinetic Dynamometer ◽  
Force Velocity ◽  
The Mean ◽  
Maximal Effort

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.

Muscle Strength, Size, and Composition Following 12 Months of Gender-affirming Treatment in Transgender Individuals

2019 ◽  
Vol 105 (3) ◽  
pp. e805-e813 ◽  
Author(s):  
Anna Wiik ◽  
Tommy R Lundberg ◽  
Eric Rullman ◽  
Daniel P Andersson ◽  
Mats Holmberg ◽  
...  
Keyword(s):  
Muscle Mass ◽  
Muscle Function ◽  
Treatment Initiation ◽  
Hormone Replacement ◽  
Knee Extensor ◽  
Muscle Volume ◽  
Muscle Size ◽  
Thigh Muscle ◽  
Cross Sectional ◽  
One Year

Abstract Context As many sports are divided in male/female categories, governing bodies have formed regulations on the eligibility for transgender individuals to compete in these categories. Yet, the magnitude of change in muscle mass and strength with gender-affirming treatment remains insufficiently explored. Objective This study explored the effects of gender-affirming treatment on muscle function, size, and composition during 12 months of therapy. Design, settings, participants In this single-center observational cohort study, untrained transgender women (TW, n = 11) and transgender men (TM, n = 12), approved to start gender-affirming medical interventions, underwent assessments at baseline, 4 weeks after gonadal suppression of endogenous hormones but before hormone replacement, and 4 and 12 months after treatment initiation. Main outcome measures Knee extensor and flexor strength were assessed at all examination time points, and muscle size and radiological density (using magnetic resonance imaging and computed tomography) at baseline and 12 months after treatment initiation. Results Thigh muscle volume increased (15%) in TM, which was paralleled by increased quadriceps cross-sectional area (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 their strength levels. Conclusions One year of gender-affirming treatment resulted in robust increases in muscle mass and strength in TM, but modest changes in TW. These findings add new knowledge on the magnitude of changes in muscle function, size, and composition with cross-hormone therapy, which could be relevant when evaluating the transgender eligibility rules for athletic competitions.

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

2007 ◽  
Vol 102 (2) ◽  
pp. 634-640 ◽  
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.

MUSCLE STRENGTH AND MRI DETERMINED THIGH MUSCLE VOLUME IN YOUNG GIRLS980

1997 ◽  
Vol 29 (Supplement) ◽  
pp. 171
Author(s):  
M. B.A. De Ste Croix ◽  
N. Armstrong ◽  
J. R. Welsman ◽  
R. J. Winsley
Keyword(s):  
Muscle Strength ◽  
Muscle Volume ◽  
Thigh Muscle

Strength training at high versus low external resistance in older adults: Effects on muscle volume, muscle strength, and force–velocity characteristics

2013 ◽  
Vol 48 (11) ◽  
pp. 1351-1361 ◽  
Author(s):  
Evelien Van Roie ◽  
Christophe Delecluse ◽  
Walter Coudyzer ◽  
Steven Boonen ◽  
Ivan Bautmans
Keyword(s):  
Older Adults ◽  
Muscle Strength ◽  
Strength Training ◽  
Muscle Volume ◽  
External Resistance ◽  
Force Velocity

scholarly journals Correlates of Physical Functioning and Performance Across the Spectrum of Kidney Function

2017 ◽  
Vol 27 (5) ◽  
pp. 579-596 ◽  
Author(s):  
E. Segura-Ortí ◽  
P. L. Gordon ◽  
J. W. Doyle ◽  
K. L. Johansen
Keyword(s):  
Physical Activity ◽  
Muscle Strength ◽  
Physical Function ◽  
Kidney Function ◽  
Physical Performance ◽  
Physical Functioning ◽  
Muscle Size ◽  
Thigh Muscle ◽  
Muscle Area ◽  
And Performance

The aim of this study was to determine the extent to which poor physical functioning, low participation in physical activity, and muscle atrophy observed among patients on hemodialysis are evident in the earlier stages of chronic kidney disease (CKD). We enrolled adults in three groups: no CKD, Stages 3 to 4 CKD, and hemodialysis. Outcomes measured were physical activity, muscle size, thigh muscle strength, physical performance, and self-reported physical function. Patients with CKD had muscle area intermediate between the no CKD and hemodialysis groups, but they had low levels of physical activity that were similar to the hemodialysis group. Physical activity and muscle size were significantly associated with all outcomes. Kidney function was not significantly associated with muscle strength or physical performance after adjustment for physical activity and muscle size. In conclusion, interventions aimed to increase muscle mass and energy expenditure might have an impact on improving physical function of CKD patients.

Optimal Peak Power in Relation to Age, Body Size, Gender, and Thigh Muscle Volume

2003 ◽  
Vol 15 (4) ◽  
pp. 406-418 ◽  
Author(s):  
Amândio M.C. Santos ◽  
Neil Armstrong ◽  
Mark B. A. De Ste Croix ◽  
Peter Sharpe ◽  
Joanne R. Welsman
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Peak Power ◽  
Significant Contribution ◽  
Multilevel Modelling ◽  
Muscle Volume ◽  
Thigh Muscle ◽  
Explanatory Variables ◽  
Force Velocity ◽  
Age Range

These studies used multilevel modelling to examine optimised peak power (PPopt) from a force velocity test over the age range 12–14 years. In the first study, body mass, stature, triceps and subscapular skinfold thicknesses of boys and girls, aged 12.3 ± 0.3 y at the onset of the study, were measured on four occasions at 6 monthly intervals. The analysis was founded on 146 PPopt determinations (79 from boys and 67 from girls). Body mass and stature were significant explanatory variables with sum of two skinfolds exerting an additional effect. No gender differences were evident but PPopt increased with age. In the second study, thigh muscle volume (TMV) was estimated using magnetic resonance imaging at test occasions two and four. The analysis, founded on a subsample of 67 PPopt determinations (39 from boys and 28 from girls), demonstrated TMV to be a significant additional explanatory variable alongside body mass and stature with neither age nor gender making a significant contribution to PPopt. Together the studies demonstrate the influence of body size and TMV on young people’s PPopt.

Measurement of thigh muscle size using tape or ultrasound is a poor indicator of thigh muscle strength

2009 ◽  
Vol 17 (3) ◽  
pp. 145-153 ◽  
Author(s):  
Kieran O'Sullivan ◽  
David Sainsbury ◽  
Richard O'Connor
Keyword(s):  
Muscle Strength ◽  
Muscle Size ◽  
Thigh Muscle ◽  
Poor Indicator

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

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.

CIRCULATING INTERLEUKIN-6 IS ASSOCIATED WITH SKELETAL MUSCLE STRENGTH, QUALITY, AND FUNCTIONAL ADAPTATION WITH EXERCISE TRAINING IN MOBILITY-LIMITED OLDER ADULTS

2019 ◽  
pp. 1-7
Author(s):  
G.J. Grosicki ◽  
B.B. Barrett ◽  
D.A. Englund ◽  
C. Liu ◽  
T.G. Travison ◽  
...  
Keyword(s):  
Older Adults ◽  
Skeletal Muscle ◽  
Muscle Strength ◽  
Interleukin 6 ◽  
Gait Speed ◽  
Muscle Size ◽  
Thigh Muscle ◽  
Specific Force ◽  
Muscle Health ◽  
Skeletal Muscle Strength

Background: Human aging is characterized by a chronic, low-grade inflammation suspected to contribute to reductions in skeletal muscle size, strength, and function. Inflammatory cytokines, such as interleukin-6 (IL-6), may play a role in the reduced skeletal muscle adaptive response seen in older individuals. Objectives: To investigate relationships between circulating IL-6, skeletal muscle health and exercise adaptation in mobility-limited older adults. Design: Randomized controlled trial. Setting: Exercise laboratory on the Health Sciences campus of an urban university. Participants: 99 mobility-limited (Short Physical Performance Battery (SPPB) ≤9) older adults. Intervention: 6-month structured physical activity with or without a protein and vitamin D nutritional supplement. Measurements: Circulating IL-6, skeletal muscle size, composition (percent normal density muscle tissue), strength, power, and specific force (strength/CSA) as well as physical function (gait speed, stair climb time, SPPB-score) were measured pre- and post-intervention. Results: At baseline, Spearman’s correlations demonstrated an inverse relationship (P<0.05) between circulating IL-6 and thigh muscle composition (r = -0.201), strength (r = -0.311), power (r = -0.210), and specific force (r = -0.248), and positive association between IL-6 and stair climb time (r = 0.256; P<0.05). Although the training program did not affect circulating IL-6 levels (P=0.69), reductions in IL-6 were associated with gait speed improvements (r = -0.487; P<0.05) in “higher” IL-6 individuals (>1.36 pg/ml). Moreover, baseline IL-6 was inversely associated (P<0.05) with gains in appendicular lean mass and improvements in SPPB score (r = -0.211 and -0.237, respectively). Conclusions: These findings implicate age-related increases in circulating IL-6 as an important contributor to declines in skeletal muscle strength, quality, function, and training-mediated adaptation. Given the pervasive nature of inflammation among older adults, novel therapeutic strategies to reduce IL-6 as a means of preserving skeletal muscle health are enticing.

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