scholarly journals Relative growth of thigh muscle size and running performance in children from 3 to 15 years

2019 ◽  
Vol 68 (6) ◽  
pp. 369-380
Author(s):  
Yohei Takai ◽  
Miyuki Nakatani ◽  
Miki Haramura ◽  
Takaya Yoshimoto ◽  
Hiroaki Kanehisa
Keyword(s):  
Muscle Size ◽  
Thigh Muscle ◽  
Relative Growth ◽  
Running Performance

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, 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 Neither repetition duration nor number of muscle actions affect strength increases, body composition, muscle size, or fasted blood glucose in trained males and females

2019 ◽  
Vol 44 (2) ◽  
pp. 200-207 ◽  
Author(s):  
Luke Carlson ◽  
Brandon Jonker ◽  
Wayne L. Westcott ◽  
James Steele ◽  
James P. Fisher
Keyword(s):  
Body Composition ◽  
Blood Glucose ◽  
Muscle Mass ◽  
Time Course ◽  
Muscle Size ◽  
Thigh Muscle ◽  
Perceived Difficulty ◽  
Barriers To Exercise ◽  
Course Changes ◽  
Muscle Actions

A key variable within resistance training (RT) is that of repetition duration: the time (seconds) taken to perform the concentric and eccentric muscle actions of a repetition. Research has produced equivocal results with regard to strength and muscle mass increases; many studies have created parity in the number of repetitions, but there has been disparity in the load used and the time under load (TUL). The purpose of this study was to compare load- and TUL-matched groups performing resistance exercise using different repetition durations. Fifty-nine male and female participants were randomized into 3 groups: 2s:4s (n = 18), 10s:10s (n = 20), or a group that performed 30 s of eccentric, 30 s of concentric, and 30 s of eccentric muscle actions (e.g., 1.5 repetitions; n = 21). Participants were supervised in one-on-one RT sessions 2 days/week for 10 weeks. Outcomes were 10 repetitions maximum (RM) and predicted 1RM for chest press, leg press, and pulldown exercises, as well as body composition, upper arm and thigh muscle mass, and fasted blood glucose. Analyses revealed significant increases in strength for all exercises but no between-group differences and no statistically significant time course changes for the other variables. Repetition duration does not affect the increases in strength in trained participants when exercise is performed to momentary failure. Because time constraints and perceived difficulty are often cited as barriers to exercise, it is important to recognize that the low-volume (single-set), machine-based protocol employed herein produced worthwhile strength increases in trained participants.

Thigh Muscle Size And Vascular Function After Blood-flow Restricted Elastic Band Training In Postmenopausal Women

2015 ◽  
Vol 47 ◽  
pp. 539
Author(s):  
Tomohiro Yasuda ◽  
Kazuya Fukumura ◽  
Toshihiro Morita ◽  
Takanobu Tomaru ◽  
Toshiaki Nakajima
Keyword(s):  
Blood Flow ◽  
Postmenopausal Women ◽  
Vascular Function ◽  
Muscle Size ◽  
Thigh Muscle ◽  
Elastic Band

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.

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 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.

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