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At least 1,081 records · Page 60Linked to original sources
PubMed1983

Knee function and muscle strength following distal ileotibial band transfer for antero-lateral rotatory instability.

In a prospective study, 60 consecutive patients underwent a distal iliotibial band transfer for anterolateral knee instability. Knee function was evaluated with a score system, static stability tests and a standardized test including thigh muscle measurements, a one-leg-jump-test and a figure-of-8 running test. At the 40-month follow-up there was a significant increase in the mean knee score. The quadriceps in the treated leg was significantly weaker than in the non-operated leg, and the quadriceps strength was significantly correlated to the knee score. The functional outcome after operation was generally unsatisfactory. Few patients attained normal values in all tests, primarily because of poor restoration of stability.

Adult↗
PubMed1993

Concentric and eccentric muscle strength before, during and after fatigue in 13 year-old boys.

The purpose of this study was to investigate the force-producing characteristics of boys aged 13 years in relation to fatigue of elbow flexor muscles. Maximal voluntary force in elbow flexion was measured before and after a muscle endurance test (MET) by using an isokinetic dynamometer isometrically, concentrically and eccentrically at three velocities, i.e. 0.21, 0.52, and 1.05 rad.s-1. The MET consisted of maximal concentric and eccentric muscle actions performed alternately at 0.52 rad.s-1 for 50 consecutive trials. Muscle cross-sectional area (CSA) of elbow flexor muscles (biceps brachii and brachialis) was measured by a B-mode ultrasound apparatus. Although eccentric force showed significantly higher values than concentric force during MET, there was no significant difference in the rate of decline in force between the two actions. There was no significant difference in the rate of decline in force after MET for each velocity and muscle action. Isometric, concentric and eccentric force before MET was significantly related to muscle CSA whereas, after MET, concentric force significantly correlated with muscle CSA but there was no significant correlation between muscle CSA and isometric or eccentric force. From our study, it is therefore suggested that in development to maturity, isometric, concentric and eccentric force decrease at the same rate with advancing muscle fatigue; however, there might be differences among muscle actions in factors affecting force development.

Adolescent↗
PubMedDate not supplied

Skeletal muscle strength in heart transplant recipients.

Knee extension (quadriceps) strength, peak oxygen consumption, and body composition were measured in 11 orthotopic heart transplant recipients (50 +/- 14 years of age) 18 +/- 12 months after transplantation and 11 untrained sedentary control subjects closely matched (p > or = 0.05) with respect to age, height, and weight. Peak oxygen consumption and absolute knee extension strength in the transplant recipients were 57% and 69% of control, respectively. Leg strength and peak oxygen consumption were not significantly correlated (p > or = 0.05) with months after transplantation. Peak oxygen consumption was significantly (p < or = 0.05) correlated with leg strength in both groups, but the relationship was greater in transplant recipients (r = 0.90) compared with the control group (r = 0.65). These data indicate that a leg-strength deficit persists up to 18 months after transplantation and the decrement in peak oxygen consumption observed in heart transplant recipients is partially explicable by skeletal muscle weakness. Our results underline the importance of progressive resistance training in comprehensive rehabilitation programs.

Exercise Test↗
PubMed2005

ACTN3 genotype is associated with increases in muscle strength in response to resistance training in women.

The alpha-actinin 3 (ACTN3) gene encodes a protein of the Z disk of myofibers, and a polymorphism of ACTN3 results in complete loss of the protein. The ACTN3 genotype (R577X) has been found to be associated with performance in Australian elite athletes (Yang N, MacArthur DG, Gulbin JP, Hahn AG, Beggs AH, Easteal S, and North K. Am J Hum Genet 73: 627-631, 2003). We studied associations between ACTN3 genotype and muscle size [cross-sectional area of the biceps brachii via magnetic resonance imaging (MRI)] and elbow flexor isometric (MVC) and dynamic [1-repetition maximum (1-RM)] strength in a large group of men (N = 247) and women (N = 355) enrolled in a 12-wk standardized elbow flexor/extensor resistance training program of the nondominant arm at one of eight study centers. We found no association between ACTN3 R577X genotype and muscle phenotype in men. However, women homozygous for the ACTN3 577X allele (XX) had lower baseline MVC compared with heterozygotes (P < 0.05) when adjusted for body mass and age. Women homozygous for the mutant allele (577X) demonstrated greater absolute and relative 1-RM gains compared with the homozygous wild type (RR) after resistance training when adjusted for body mass and age (P < 0.05). There was a trend for a dose-response with genotype such that gains were greatest for XX and least for RR. Significant associations were validated in at least one ethnic subpopulation (Caucasians, Asians) and were independent of training volume. About 2% of baseline MVC and of 1-RM strength gain after training were attributable to ACTN3 genotype (likelihood-ratio test P value, P = 0.01), suggesting that ACTN3 is one of many genes contributing to genetic variation in muscle performance and adaptation to exercise.

Actinin↗
PubMed2002

Chronic inflammation and the effect of IGF-I on muscle strength and power in older persons.

Deregulation of the inflammatory response plays a major role in the age-related decline of physical performance. The causal pathway leading from inflammation to disability has not been fully clarified, but several researches suggest that interleukin-6 (IL-6) causes a reduction of physical performance in elderly through its effect on muscle function. In vitro studies demonstrated that IL-6 inhibits the secretion of insulin-like growth factor I (IGF-I) and its biological activity, suggesting that the negative effect of IL-6 on muscle function might be mediated through IGF-I. We evaluated the joint effect of IGF-I and IL-6 on muscle function in a population-based sample of 526 persons with a wide age range (20-102 yr). After adjusting for potential confounders, such as age, sex, body mass index, IL-6 receptor, and IL-6 promoter polymorphism, IL-6, IGF-I, and their interaction were significant predictors of handgrip and muscle power. In analyses stratified by IL-6 tertiles, IGF-I was an independent predictor of muscle function only in subjects in the lowest IL-6 tertile, suggesting that the effect of IGF-I on muscle function depends on IL-6 levels. This mechanism may explain why IL-6 is a strong risk factor for disability.

Adult↗