scholarly journals ACTN3 genotype is associated with muscle phenotypes in women across the adult age span

2008 ◽  
Vol 105 (5) ◽  
pp. 1486-1491 ◽  
Author(s):  
Sean Walsh ◽  
Dongmei Liu ◽  
E. Jeffrey Metter ◽  
Luigi Ferrucci ◽  
Stephen M. Roth
Keyword(s):  
Muscle Strength ◽  
Knee Extensor ◽  
Peak Torque ◽  
Fat Free Mass ◽  
Isokinetic Dynamometry ◽  
Adult Age ◽  
Encoding Gene ◽  
Total Body ◽  
Torque Values ◽  
Adult Volunteers

The R577X polymorphism in the α-actinin-3 encoding gene ( ACTN3) has been associated with elite athletic performance, and recently with differences in isometric and dynamic muscle strength and power in the general population. In this study we sought to determine the association of ACTN3 R577X genotype with muscle strength and mass phenotypes in men and women across the adult age span. Eight hundred forty-eight ( n = 848) adult volunteers (454 men and 394 women) aged 22–90 yr were genotyped for ACTN3 R577X. Knee extensor (KE) shortening and lengthening peak torque values were determined using isokinetic dynamometry and fat-free mass (FFM) by dual-energy X-ray absorptiometry. Women deficient in α-actinin-3 (X/X; n = 53) displayed lower KE shortening peak torque (30°/s: 89.5 ± 3.5 vs. 99.3 ± 1.4 N·m, P = 0.011; 180°/s: 60.3 ± 2.6 vs. 67.0 ± 1.0 N·m, P = 0.019) and KE lengthening peak torque (30°/s: 122.8 ± 5.7 vs. 137.0 ± 2.2 N·m, P = 0.022; 180°/s: 121.8 ± 5.8 vs. 138.5 ± 2.2 N·m, P = 0.008) compared with R/X + R/R women ( n = 341). Women X/X homozygotes also displayed lower levels of both total body FFM (38.9 ± 0.5 vs. 40.1 ± 0.2 kg, P = 0.040) and lower limb FFM (11.9 ± 0.2 vs. 12.5 ± 0.1 kg, P = 0.044) compared with R/X + R/R women. No genotype-related differences were observed in men. In conclusion, our results indicate that the absence of α-actinin-3 protein (i.e., ACTN3 X/X genotype) influences KE peak torque and FFM in women but not men.

scholarly journals Pre- and Post-Operative Limb Symmetry Indexes and Estimated Preinjury Capacity Index of Muscle Strength as Predictive Factors for the Risk of ACL Reinjury: A Retrospective Cohort Study of Athletes after ACLR

2021 ◽  
Vol 11 (8) ◽  
pp. 3498
Author(s):  
Martin Rudolf Zore ◽  
Nevenka Kregar Velikonja ◽  
Mohsen Hussein
Keyword(s):  
Muscle Strength ◽  
Cruciate Ligament ◽  
Knee Extensor ◽  
Peak Torque ◽  
Secondary Injury ◽  
Flexor Muscle ◽  
Acl Injuries ◽  
Secondary Injuries ◽  
Operative Limb ◽  
Torque Values

Long-term muscle weakness may increase the risk of knee reinjury after anterior cruciate ligament reconstruction (ACLR) and of osteoarthritis. The incidence of secondary injuries after ACLR and the predictive value of preoperative and postoperative limb symmetry index (LSI) and estimated preinjury capacity (EPIC) index were studied for predicting the risk of reinjury in a retrospective study. Sixty-three recreational and professional athletes after ACLR with hamstring autograft were followed for secondary injury in the period from 2012 to 2014, 5 years after ACLR. Peak torque values of knee extensor and flexor muscle strength of the involved and uninvolved limb were measured with an isokinetic dynamometer at 60 degrees per second before ACLR and 6 months after ACLR and were used to calculate LSI and EPIC index. The results suggest that the preoperative LSI and EPIC indexes predict a secondary ACL injury better than the postoperative LSI for extensor muscles which is often used as a criterion to determine the time for returning to normal sports activities. Individuals with secondary ACL injuries suffer greater loss of knee extensor muscle strength of the uninvolved limb between preoperative and postoperative ACLR testing compared to the individuals without secondary injury.

CNTF genotype is associated with muscular strength and quality in humans across the adult age span

2001 ◽  
Vol 90 (4) ◽  
pp. 1205-1210 ◽  
Author(s):  
Stephen M. Roth ◽  
Matthew A. Schrager ◽  
Robert E. Ferrell ◽  
Steven E. Riechman ◽  
E. Jeffrey Metter ◽  
...  
Keyword(s):  
Muscle Mass ◽  
Body Mass ◽  
Muscular Strength ◽  
Peak Torque ◽  
Fat Free Mass ◽  
Muscle Quality ◽  
Knee Extensors ◽  
Muscular Power ◽  
Adult Age ◽  
The Relationship

The relationship between ciliary neurotrophic factor (CNTF) genotype and muscle strength was examined in 494 healthy men and women across the entire adult age span (20–90 yr). Concentric (Con) and eccentric (Ecc) peak torque were assessed using a Kin-Com isokinetic dynamometer for the knee extensors (KE) and knee flexors (KF) at slow (0.52 rad/s) and faster (3.14 rad/s) velocities. The results were covaried for age, gender, and body mass or fat-free mass (FFM). Individuals heterozygous for the CNTF null (A allele) mutation (G/A) exhibited significantly higher Con peak torque of the KE and KF at 3.14 rad/s than G/G homozygotes when age, gender, and body mass were covaried ( P < 0.05). When the dominant leg FFM (estimated muscle mass) was used in place of body mass as a covariate, Con peak torque of the KE at 3.14 rad/s was also significantly greater in the G/A individuals ( P < 0.05). In addition, muscle quality of the KE (peak torque at 3.14 rad · s−1 · leg muscle mass−1) was significantly greater in the G/A heterozygotes ( P < 0.05). Similar results were seen in a subanalysis of subjects 60 yr and older, as well as in Caucasian subjects. In contrast, A/A homozygotes demonstrated significantly lower Ecc peak torque at 0.52 rad/s for both KE and KF compared with G/G and G/A groups ( P < 0.05). No significant relationships were observed at 0.52 rad/s between genotype and Con peak torque. These data indicate that individuals exhibiting the G/A genotype possess significantly greater muscular strength and muscle quality at relatively fast contraction speeds than do G/G individuals. Because of high positive correlations between fast-velocity peak torque and muscular power, these findings suggest that further investigations should address the relationship between CNTF genotype and muscular power.

A Longitudinal Study of Quantitative Muscle Strength and Functional Motor Ability in Ambulatory Boys with Duchenne Muscular Dystrophy

2021 ◽  
pp. 1-14
Author(s):  
Cathleen E. Buckon ◽  
Susan E. Sienko ◽  
Eileen G. Fowler ◽  
Anita M. Bagley ◽  
Loretta A. Staudt ◽  
...  
Keyword(s):  
Longitudinal Study ◽  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Muscle Strength ◽  
Genetic Disorder ◽  
Knee Extensor ◽  
Standard Of Care ◽  
Rate Of Change ◽  
Isokinetic Dynamometry ◽  
Gross Motor

Background: Duchenne muscular dystrophy (DMD) is an X-linked recessive genetic disorder, that is characterized by progressive muscle degeneration and loss of ambulation between 7–13 years of age. Novel pharmacological agents targeting the genetic defects and disease mechanisms are becoming available; however, corticosteroid (CS) therapy remains the standard of care. Objective: The purpose of this longitudinal study was to elucidate the effect of CS therapy on the rate of muscle strength and gross motor skill decline in boys with DMD and assess the sensitivity of selected outcome measures. Methods: Eighty-four ambulatory boys with DMD (49–180 months), 70 on CS, 14 corticosteroid naïve (NCS), participated in this 8-year multi-site study. Outcomes included; isokinetic dynamometry, the Standing (STD) and Walking/Running/jumping (WRJ) dimensions of the Gross Motor Function Measure (GMFM), and Timed Function Tests (TFTs). Nonlinear mixed modeling procedures determined the rate of change with age and the influence of steroids. Results: Despite CS therapy the rate of decline in strength with age was significant in all muscle groups assessed. CS therapy significantly slowed decline in knee extensor strength, as the NCS group declined at 3x the rate of the CS group. Concurrently, WRJ skills declined in the NCS group at twice the rate of the CS group. 4-stair climb and 10 meter walk/run performance was superior in the boys on CS therapy. Conclusion: CS therapy slowed the rate of muscle strength decline and afforded longer retention of select gross motor skills in boys on CS compared to boys who were NCS. Isokinetic dynamometry, Walk/Run/Jump skills, and select TFTs may prove informative in assessing the efficacy of new therapeutics in ambulatory boys with DMD.

Hamstring Flexibility Is Not Correlated with Isokinetic Knee Muscle Strength in Female Modern Dancers

2018 ◽  
Vol 33 (2) ◽  
pp. 95-101 ◽  
Author(s):  
Ani Agopyan
Keyword(s):  
Muscle Strength ◽  
Knee Extensor ◽  
Peak Torque ◽  
Flexor Muscle ◽  
Work Production ◽  
University Level ◽  
Modern Dancers ◽  
Hamstring Flexibility ◽  
Knee Muscle ◽  
The Right

OBJECTIVE: To evaluate bilateral isokinetic knee extensor and flexor muscle strength relative to hamstring flexibility in female modern dancers. METHODS: 20 trained university-level female modern dance students (mean age 23.8±3.8 yrs) volunteered for the study. Concentric isokinetic peak torque (PT, in Nm), peak torque % of body weight (PT%BW, in Nm/kg), and total work (TW, in J) of the knee extensor and flexor muscles for each leg were measured with a dynamometer at a velocity of 60, 180, and 300°/s. Hamstring flexibility of both limbs was assessed by a goniometer with the subjects in a supine position using the active straight leg raise (SLR) test. Participants were divided into flexible (n=10) and highly flexible (n=10) groups based on their hamstring flexibility. RESULTS: The flexible and highly flexible groups had significant differences (p≤0.05) for the right (flexible, 119.7±4.3°; highly flexible, 137.7±2.6°) and left active SLR tests (flexible, 120.6±5.3°; highly flexible, 138.3±4.5°). No significant differences were found between the flexible and highly flexible dancers for concentric knee extensor and flexor muscle strength in all selected parameters (p≤0.05). There were also no significant correlations between flexibility and bilateral PT, PT%BW, and TW scores (60, 180, and 300°/s) of dancers at the concentric contraction (p≤0.05). CONCLUSION: These findings indicate that hamstring flexibility (for both the flexible and highly flexible groups) is not correlated with knee strength and has no impact on torque and work production during maximal concentric isokinetic knee muscle action in university-level female modern dancers.

scholarly journals Velocity-specific knee strength between professional and under-17 female volleyball player

2019 ◽  
Vol 75 (1) ◽  
Author(s):  
Alexandre R.M. Pelegrinelli ◽  
Laís F. Dela Bela ◽  
Mariana F. Silva ◽  
Lucas C.R. Rodrigues ◽  
João P. Batista ◽  
...  
Keyword(s):  
Muscle Strength ◽  
Knee Extensor ◽  
Peak Torque ◽  
Total Work ◽  
Flexor Muscle ◽  
Mean Power ◽  
Cross Sectional ◽  
Significant Group ◽  
Surface Maps ◽  
Volleyball Players

Background: Many studies have investigated isokinetic performance in volleyball players but not through surface maps.Objectives: The goals of this study were to assess velocity-specific isokinetic knee extensor–flexor muscle strength and to compare the isokinetic knee extensor–flexor muscles between professional (PRO) and under-17 (U17) female volleyball players.Method: This cross-sectional laboratory study was developed with two groups: PRO (n = 12), medianage = 21.3 years, and U17 (n = 9), medianage = 15 years. Peak torque, total work, mean power, angle of peak torque, hamstring–quadriceps torque ratio (H–Q ratio) and torque–angle–velocity surface maps were analysed from knee extension–flexion at 60, 120 and 300 degrees per second (°/s).Results: Significant differences were identified for extensor peak torque between PRO x = 202.3 Newton metre (N·m) (standard deviation [SD] = 24.4) and U17 x = 141.6 N·m (30.1) at 60 °/s (p < 0.001; d = 2.21) as well as flexor peak torque (PRO x = 75.7 N·m [10.3] and U17 x = 57.7 N·m [11.4]) at 120 °/s (p < 0.001; d = 1.65) for the dominant limb. There were also significant group differences for total work and mean power at all velocities for extension and flexion. Surface maps demonstrated higher torque at lower speeds for both groups with smaller torque changes across velocities for flexion.Conclusion: Different groups of female volleyball players showed contrasting concentric knee muscle strength across isokinetic velocities.Clinical implications: These results demonstrate the importance of specific strength training for different age groups, even within the same sport, and provide insight into muscle strength.

scholarly journals Low Body Fat Does Not Influence Recovery after Muscle-Damaging Lower-Limb Plyometrics in Young Male Team Sport Athletes

2020 ◽  
Vol 5 (4) ◽  
pp. 79
Author(s):  
John F. T. Fernandes ◽  
Kevin L. Lamb ◽  
Craig Twist
Keyword(s):  
Body Composition ◽  
Muscle Damage ◽  
Body Fat ◽  
Knee Extensor ◽  
Young Male ◽  
Peak Torque ◽  
Team Sport ◽  
Flight Time ◽  
Fat Free Mass ◽  
Plyometric Exercise

Aim: This study assessed the influence of fat mass to fat-free mass ratio (FM:FFM) on recovery from plyometric exercise. Method: After assessment of body composition, 20 male team sport players (age 20.7 ± 1.1 years; body mass 77.1 ± 11.5 kg) were divided into low- (n = 10; 0.11 ± 0.03) and normal- (n = 10; 0.27 ± 0.09) fat groups based on FM:FFM ratio. Thereafter, participants completed measurements of knee extensor torque at 60 and 240°∙s−1, countermovement jump flight time, plasma creatine kinase (CK) activity and perceived muscle soreness (VAS) before and at 0, 24 and 48 h after 10 × 10 maximal plyometric vertical jumps. Results: Evidence of muscle damage was confirmed by alterations in VAS, peak torque at 60 and 240°∙s−1 and flight time at 0, 24 and 48 h after plyometric exercise (P < 0.05). CK was increased at 0 and 24 h (P < 0.05) but returned to baseline values by 48 h. No time by group effects were observed for any of the dependent variables (P > 0.05). Conclusion: The current findings indicate that while muscle damage was present after plyometric exercise, the magnitude was similar across the two body composition groups. Applied practitioners can allow for a similar recovery time after plyometric exercise in those with low and normal body fat.

Effects of an Alleged Myostatin-Binding Supplement and Heavy Resistance Training on Serum Myostatin, Muscle Strength and Mass, and Body Composition

2004 ◽  
Vol 14 (4) ◽  
pp. 461-472 ◽  
Author(s):  
Darryn S. Willoughby
Keyword(s):  
Body Composition ◽  
Resistance Training ◽  
Muscle Strength ◽  
Serum Levels ◽  
Fat Free Mass ◽  
Double Blind ◽  
Total Body Mass ◽  
Before And After ◽  
Heavy Resistance Training ◽  
Total Body

This study examined 12 wk of resistance training and cystoseim canariensis supplementation on serum levels of myostatin and follistatin-like related gene (FLRG) and muscle strength and body composition. Twenty-two untrained males were randomly assigned to a placebo (PLC) or myostatin binder (MYO) group in a double-blind fashion. Blood was obtained before and after 6 and 12 wk of training. PLC and MYO trained thrice weekly using 3 sets of 6 to 8 repetitions at 85% to 90% 1 repetition maximum. MYO ingested 1200 mg/d of cystoseim canariensis. Data were analyzed with 2-way ANOVA. After training, total body mass, fat-free mass, muscle strength, thigh volume/mass, and serum myostatin and FLRG increased for both groups (P < 0.05); however, there were no differences between groups (P > 0.05). Twelve wk of heavy resistance training and 1200 mg/d of cystoseim canariensis supplementation appears ineffective at inhibiting serum myostatin and increasing muscle strength and mass or decreasing fat mass.

A cross-sectional study of muscle strength and mass in 45- to 78-yr-old men and women

1991 ◽  
Vol 71 (2) ◽  
pp. 644-650 ◽  
Author(s):  
W. R. Frontera ◽  
V. A. Hughes ◽  
K. J. Lutz ◽  
W. J. Evans
Keyword(s):  
Muscle Strength ◽  
Peak Torque ◽  
Cross Sectional Study ◽  
Fat Free Mass ◽  
Knee Extensors ◽  
Cross Sectional ◽  
Men And Women ◽  
Age Related ◽  
Muscle Groups ◽  
Old Men

The isokinetic strength of the elbow and knee extensors and flexors was measured in 200 healthy 45- to 78-yr-old men and women to examine the relationship between muscle strength, age, and body composition. Peak torque was measured at 60 and 240 degrees/s in the knee and at 60 and 180 degrees/s in the elbow by use of a Cybex II isokinetic dynamometer. Fat-free mass (FFM) was estimated by hydrostatic weighing in all subjects, and muscle mass (MM) was determined in 141 subjects from urinary creatinine excretion. FFM and MM were significantly lower (P less than 0.001) in the oldest group. Strength of all muscle groups at both testing speeds was significantly (P less than 0.006) lower (range 15.5–26.7%) in the 65- to 78- than in the 45- to 54-yr-old men and women. When strength was adjusted for FFM or MM, the age-related differences were not significant in all muscle groups except the knee extensors tested at 240 degrees/s. Absolute strength of the women ranged from 42.2 to 62.8% that of men. When strength was expressed per kilogram of MM, these gender differences were smaller and/or not present. These data suggest that MM is a major determinant of the age- and gender-related differences in skeletal muscle strength. Furthermore, this finding is, to a large extent, independent of muscle location (upper vs. lower extremities) and function (extension vs. flexion).

scholarly journals Resistance training-induced gains in knee extensor strength are related to increased neural cell adhesion molecule expression in older adults with knee osteoarthritis

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Thomas B. Voigt ◽  
Timothy W. Tourville ◽  
Michael J. Falcone ◽  
James R. Slauterbeck ◽  
Bruce D. Beynnon ◽  
...  
Keyword(s):  
Older Adults ◽  
Muscle Strength ◽  
Cell Adhesion Molecule ◽  
Knee Extensor ◽  
Peak Torque ◽  
Neural Adaptations ◽  
Mhc Ii ◽  
Neural Cell Adhesion ◽  
Fiber Size ◽  
Whole Muscle

Abstract Objective Resistance training (RT) can improve whole muscle strength without increasing muscle fiber size or contractility. Neural adaptations, which lead to greater neural activation of muscle, may mediate some of these improvements, particularly in older adults, where motor neuron denervation is common. The purpose of this study was to explore the relationship of neural adaptations, as reflected by neural cell adhesion molecule (NCAM) expression, to improvements in (1) whole muscle strength and (2) muscle fiber size following RT in older adults with knee osteoarthritis. We performed whole muscle strength measurements and immunohistochemical analysis of fiber size, type, and NCAM expression before and after a 14-week RT program. Results RT increased whole-muscle strength as measured by 1-repetition maximum (1-RM) leg press (P = 0.01), leg extension (P = 0.03), and knee extensor peak torque (P = 0.050), but did not alter NCAM expression. Greater NCAM expression in myosin heavy chain (MHC) II fibers was associated with greater whole muscle strength gains (knee extensor peak torque r = 0.93; P < 0.01) and greater MHC II fiber size (r = 0.79; P < 0.01). Our results suggest that training-induced NCAM expression, and neural adaptations more generally, may be important for RT-induced morphological and functional improvements in older adults. Trial registration NCT01190046

scholarly journals Results and analyses of preoperative isokinetic and balance tests in patients with chronic lateral ankle instability who underwent surgical treatments

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0047
Author(s):  
Ki-Sun Sung ◽  
Dae-Wook Kim
Keyword(s):  
Muscle Strength ◽  
Postural Stability ◽  
Ankle Instability ◽  
Peak Torque ◽  
Balance Test ◽  
Lateral Ankle ◽  
Chronic Lateral Ankle Instability ◽  
Balance Tests ◽  
Lateral Ankle Instability ◽  
Torque Values

Category: Sports Introduction/Purpose: To (1) describe muscle strength and postural stability in patients with chronic lateral ankle instability, and (2) analyze the correlation between weakness of muscle strength and deficits of postural stability Methods: Results of preoperative isokinetic and balance tests in 203 patients whose contralateral ankle was normal were retrospectively reviewed. Isokinetic peak torque values of eversion and inversion at 2 angular velocities (30°/s, 120°/s) were measured in injured and normal ankles. In balance test, the percent differences of 3 actual scores (Overall, Anterior-Posterior, and Medial-Lateral) between injured and normal ankles were calculated. Additional statistical analyses were performed to describe weakness of muscle strength, deficits of postural stability, and their correlation. Results: There were significant differences in 4 peak torque values and 4 relative peak torque values (peak torque/body weight) between injured and normal ankles. Eight values were significantly lower in injured ankles. Weakness was severe during inversion and at 30°/s. In balance test, 49 subjects (24.1%) had significant deficits in postural stability; the results in 109 subjects (53.7%) were favorable. There was no strong association between weakness of muscle strength and deficits of postural stability. Conclusion: Considering correlation between weakness of muscle strength and deficits of postural stability, strength measurement alone is insufficient in evaluating preoperative functional ability, and other functional test such as postural stability test is required. In addition, the results of this study may provide further evidence for rehabilitation program consisting of proprioceptive training as well as muscle strengthening.

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