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At least 1,117 records · Page 62Linked to original sources
PubMed1992

Intact conduction of fastest corticospinal efferents is not sufficient for normal voluntary muscle strength: transcranial motor cortex stimulation in patients with tetraplegia.

In six patients with chronic severe tetraparesis, caused by closed head injury (3 cases), basilar thrombosis (2 cases) or global hypoxia (1 case), responses of suprathreshold transcranial magnetic stimulation of motor cortex to thenar and abductor hallucis muscles on both sides were studied. Results showed in most patients normal thresholds and latencies (17 out of 24 latencies within normal +/- 2 S.D., 20 thresholds within normal +/- 1 S.D.) and amplitudes of even higher than normal values. Latencies or thresholds did not correlate with severity of pareses and were in marked contrast to the severe pareses of the muscles under investigation. Despite different etiology CT-scans showed diffuse atrophy of cerebral white matter as a common finding. It is concluded that intact descending corticospinal motor pathways are a necessary but not a sufficient condition for voluntary motor function.

Adolescent↗
PubMed2004

Gene powered? Where to go from heritability (h2) in muscle strength and power?

The importance of genetic and environmental factors in muscular strength and power variation has been reported in the last two decades. However, there is a paucity of data on gender- and age-specific estimates of heritabilities. Linkage and association studies that aim to identify genes and gene variants for muscular strength are only emerging.

Environment↗
PubMed1979

Increase of muscle strength from isometric quadriceps exercises at different knee angles.

Isometric quadriceps exercises were performed at two different knee angles, 15 and 60 degrees respectively. The maximal torque was measured in both positions before and after training in 10 healthy females. Both legs were exercised, one at each position. The purpose was to develop practical recommendations for choice of training position. The strength increase was mainly specific according to the angle at which the knee was exercised. It was suggested that isometric exercise would preferably be performed at different knee angles to secure an optimal total strength increase. Isometric exercises improved dynamic strength at a low velocity but not at a high velocity.

Adult↗
PubMed2002

Interplay among the changes of muscle strength, cross-sectional area and maximal explosive power: theory and facts.

A model has recently been proposed to predict the changes of mechanical power (W) during a maximal explosive effort (such as a standing high jump off both feet) following an adaptation (e.g. training/de-training). The model is based on the assumption that, all other things being equal (ceteris paribus), the predicted changes in W depend on the measured changes of muscle force (F) or cross-sectional area (CSA) only. It follows that, if the measured changes in W are not equal to those predicted by the model, factors other than a change in F (or CSA) must be responsible for this difference. The model does not allow the determination of factors specifically involved in the adaptation process but it helps in discriminating whether an adaptation has taken place at a local level (when the observed changes in F would be attributed to factors other than the observed changes in CSA, e.g. co-contractions, fibre type modifications...), or at a central level (when the observed changes in W would be attributed to other factors than the observed changes in F, e.g. co-ordination of multiple joints and muscle groups...), or in both regions. In this paper the model has been applied to data reported in the literature on disuse (BR, bed rest), de-conditioning (SF, space flight), strength training (ST) and de-training (DT). The results of these calculations have confirmed previous observations on the determinants of the adaptation process and further suggest: (1) that training for one specific motor task (e.g. ST) could affect the performance of a second task (e.g. a maximal explosive jump) but that, as soon as the trained motor task is terminated (DT), this ability is re-gained; and (2) that neuromuscular impairment in disuse (BR) is closer to de-training than to the de-conditioning brought about by weightlessness (SF).

Anatomy, Cross-Sectional↗
PubMed1975

Enzyme activities and muscle strength after "sprint training" in man.

Sprint type strength training was performed 3-4 times a week for 8 weeks by 4 healthy male students (16-18 yrs). The training was carried out on a treadmill at high speed and with high inclination. Muscle biopsies were obtained from vastus lateralis before and after the training period for histochemical classification of slow and fast twitch muscle fibres and for biochemical determination of metabolites and enzyme activities. Muscle fibre type distribution was unchanged, whereas fibre area indicated an increase for both fibre types in 3 subjects after training. The muscle enzyme activities of Mg2+ stimulated ATPase, myokinase and creatine phosphokinase increased 30, 20, and 36 percent, respectively. Muscle concentration of ATP and creatine phosphate (CP) did not change with training. Sargent's jump increased with on average 4 cm (from 47 to 51 cm), maximal voluntary contraction (MVC) with 19 kp (from 165 to 184 kp), and endurance at 50 percent of MVC with 9 s (from 47 to 56 s), respectively. After training all subjects showed a gain in body weight (mean 1.4 kg) and in thigh circumference (mean 1.5 cm) indicating a larger leg muscle volume and consequently also an increase in total ATP and CP.

Actomyosin↗
PubMedDate not supplied

The effect of physical training on patients with rheumatoid arthritis: changes in disease activity, muscle strength and aerobic capacity. A clinically controlled minimized cross-over study.

For decades, physical training of rheumatoid arthritis (RA)-patients has been controversial, especially for patients with active disease. The aim of this study was to investigate whether RA-patients could receive graduated training without increasing the activity of the disease. In a controlled cross-over study the effect of graduated progressive training has been evaluated in 18 RA-patients with moderately active disease. The training was performed twice weekly with aerobic conditioning and strength exercises progressing to strenuous exercises over an 8-week period. The design was a crossover project with two groups obtained by minimisation. After training the patients had significantly fewer swollen joints than before. Training of the muscles acting over the swollen joints resulted in more than a 35% decrease in the number of swollen joints. The hemoglobin level increased significantly after the training period. The erythrocyte sedimentation rate, the complement factor C3d, and the number of sore joints remained unchanged. A decrease in the need for medicine was non-significant. From this study it appears that RA-patients with some activity are trainable without aggravating the disease, even in the chronically swollen joints. The rheumatoid arthritis activity decreased with fewer swollen joints and higher hemoglobin level after training.

Adult↗
PubMed1985

Isokinetic measurements of muscle strength in hysterical paresis.

The torque during isokinetic knee extensions and flexions was determined in repeated tests at 3 speeds of angular rotation in 25 patients with pareses considered to be hysterical after relevant examinations and follow-up. The torque records were combined with surface EMG from the quadriceps and the hamstring muscles in some patients. Besides the weakness, 3 signs were observed that are not usually seen in patients with pareses due to verified peripheral or central lesions. These signs were: Enlarged variability of torque in repeated tests of the same movement (larger than 20% of maximum torque in 22 patients). Higher torque in fast movements than in slow movements (8 patients). Force production in knee flexion less than that expected from the weight of leg and lever arm due to restraining activation of the quadriceps muscle (12 patients). The restraint was present although there was no spasticity. The signs reflect inconsistent and contradictory motor performance that is not compatible with a genuine paresis. Thus, they aid the identification of weakness of functional origin.

Adult↗
PubMed1979

Muscle strength and body composition as determinants of blood pressure in young men.

The correlations of blood pressure to various indices of muscularity and fatness were studied in 183 young healthy men (mean age 19.7, SD 2.1 years). Systolic pressure showed significant positive correlations with body fat percentage, isometric strength of trunk extensors, body mass index, lean body mass, strength of leg extensors, heart rate, and the sum of four skinfolds. Diastolic pressure had significant positive correlations with body mass index, lean body mass, body fat percentage, sum of skinfolds, strength of leg extensors, strength of trunk extensors, and age. A stepwise selective multiple regression analysis for systolic pressure resulted in four significantly correlating variables: body fat percentage (p less than 0.001), heart rate (p less than 0.01), lean body mass (p less than 0.05), and strength of trunk extensors per kg body weight (p less than 0.05). For diastolic pressure the analysis resulted in two explaining variables: body mass index (p less than 0.001) and age (p less than 0.05). In a regression equation with 13 variables the strength of trunk flexors was negatively correlated with diastolic pressure. It is concluded that both fatness and muscularity are factors related to blood pressure in young men. The muscularity effect is more clearly associated with trunk and leg extensor strength.

Adipose Tissue↗