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At least 19 recordsLinked to original sources
PubMed1979

Serial isometric contractions under imposed myotatic stretch conditions in high-strength and low-strength men.

The immediate effects of an imposed myotatic stretch on knee extensor force were studied in 12 high-strength and 12 low-strength men. Under nonfatigued pre-exercise conditions, significant tension increases of 6.5% for the high-strength group and 11.0% for low-strength subjects were observed as a result of the imposed stretch. An exercise treatment involving 28 serial isometic contractions, each of 5 s duration, with an intertrial rest period of 10 s was administered. This fatiguing exercise resulted in significant decrements in strength on the order of 28.0% and 18.5% for the high-strength and low-strength groups, respectively. A Similar treatment which included a 1 s imposed myotatic stretch during each trial resulted in a greater strength decrement for the low-strength group (26.4%) than for the high-strength subjects (15.0%). A neural factor involving the stretch reflex is tentatively suggested as a plausible explanation accounting for the observation that high-strength subjects fatigue faster than low-strength subjects under conditions of isometric exercise, while low-strength subjects fatigue faster than high-strength individuals in isometric exercise which is performed with an imposed stretch.

Adult↗
PubMed1977

[Bond strength between nonprecious metal alloy and porcelain. (Part 2) Effects of the addition of Mn, Mo, Si, Sn, Ta and Ti on bond strength of 80 Ni-20 Cr alloy (author's transl)].

Alloys added 2, 4 and 6 wt% Mn, Mo, Si, Sn, Ta and Ti to 80 wt% Ni-20 wt% Cr alloyand no-added 80 wt% Ni-20 wt% Cr alloy were prepared and casted to obtain the test specimens 3 mm in diameter 25 mm in length. Ceramco porcelain (B.F. Vacuum Porcelain) was fused to each of these specimens, and the bond strength was measured by the pull-out method which applies shear stress to the metal/porcelain interface to investigate the effect of each addition element. The test results may be summarized as presented below. 1) The bond strength between the 80 Ni-20 Cr alloy and the porcelain was 182 +/- 14 kg/cm2. 2) Of the six kinds of addition elements, it was Mo, Sn, Ta and Ti that increased the bond strength. 3) The bond strength between the alloy added 6 wt% Ti to the 80 Ni-20 Cr alloy and the porcelain was 319 +/- 8 kg/cm2, which was increased by about 75% over the strength between the 80 Ni-20 Cr alloy and the porcelain.

Chromium↗
PubMed1976

[Bond strength between nonprecious metal alloy and porcelain. Part (1). Bond strength with press condensing method (author's transl)].

For the purpose of finding out the method which is able to evaluate nonprecious metal/porcelain bond strength easily, Ceramco procelain was fused to casted Wiron "S" (3 mm diameter), by means of 5 types of press condensing methods; the bond strength was measured by pull out method and these condensing methods were compared. Results are follows: (1) No significant difference was observed between conventional condensing method and press condensing method (condensing pressure; 472-1 415 kg/cm2), and the bond strength of Ceramco Paint-O-Pake porcelain to Wiron "S" was about 245-369 kg/cm2. (2) Bond strength was decreased with the decrease of the fused length of procelain. (3) Bond strength was increased approximately three times, when specimens were mounted by dental stone.

Dental Alloys↗
PubMed1978

The shear strength of trabecular bone from the femur, and some factors affecting the shear strength of the cement-bone interface.

The shear strength of trabecular bone from the femur has been studied. In general, the strongest trabecular bone is found close to the cortico-cancellous junction, though its shear strength depends also on the relationship of the trabeculae to the plane of shear. Some factors affecting the shear strength of the cement-bone interface have been investigated. In vitro, maximal cement-bone interface shear strength is obtained by exposing and thoroughly cleaning strong trabecular bone, and then forcing onto it under pressure low viscosity cement.

Adhesiveness↗
PubMed1978

Studies on mechanical strength of bone. II. Torsional strength of cortial bone after rigid plate fixation with and without compression.

Biomechanical properties of intact rabbit tibio-fibulae were investigated with torional loading 1 day to 36 weeks after fixation using 4-hole stainless steel ASIF/DCP plates with and without compression. During the first 12 weeks energy absorption and torque moment increased slightly as a result of subperiosteal new bone formation following application of the plates. There was a concomitant increase in the yielding properties of the bone, reflecting progressive porotic transformation. Thereafter, up to 36 weeks postoperatively, the values for energy absorption, torque moment and angular deformation gradually declined in both groups of bones. The differences between normal control bones and plated bones at 36 weeks were 70.1, 53.0 and 26.3 per cent, respectively. The decay of torsional strength was the same whether or not compression was used in the plate fixation. The results suggest that even in normal bone rigid plates induce a considerable loss of strength due to the cancellous transformation they are known to cause in cortical bone.

Animals↗
PubMed1978

Studies on mechanical strength of bone. I. Torsional strength of normal rabbit tibio-fibular bone.

A method is described for testing torsional strength in small cortical bones at low velocities. The linearity and precision of the testing equipment, and the effect of the dimensions and chemical composition of the bone on torsional properties are analysed. Rabbit tibio-fibular bones exhibited right-to-left differences in energy absorption capacity (up to 10.0 per cent), torsional rigidity (7.1 per cent), torque moment at fracture (6.3 per cent) and angular deformation (5.7 per cent). The scatter in energy absorption was more dependent on differences in angular deformation (strain) than on differences in torque moment (stress). No statistically significant dominance of either side could be observed. The biomechanical properties of the bones were dependent on the body weight of the test animal and the transverse dimensions of the bone, but were not influenced by the small variations measured in the chemical composition of normal bone.

Animals↗
PubMed1979

[Studies of dental methacrylic resin. (Part 7) Adhesive strength of fluid methacrylic resin to polymethylmethacrylates with various cross-linked density (author's transl)].

Heat-curing methacrylic resins cross-linked with three kinds of dimethacrylates, i.e. EDMA, tri-EDMA and nona-EDMA, were prepared, and the tensile adhesive strength of fluid methacrylic resin to them was examined. The results obtained were as follows. (1) To adherent resin cross-linked with EDMA, the adhesive strength of fluid resin showed the maximum at the concentration near 2 mole% and decreased with increasing the concentration. (2) To adherent resin cross-linked with tri-EDMA or nona-EDMA, the effect of the concentration of cross-linking agent on the adhesive strength was little, except that the adhesive strength to the latter adherent resin showed a steep increase in the range of lower concentration. (3) The adhesive strength did not appreciably change in the range of L/P ratio of fluid resin from 0.57 to 0.71 ml/g. (4) The adhesive strength under the wet condition decreased about 40 to 50% compared under the dry condition. (5) To cross-linked adherent resin, the adhesive strength of fluid resin was somewhat higher than that of self-curing resin under the dry condition. But, under the wet condition this difference was little. (6) Contrarily, to non-cross-linked adherent resin, the adhesive strength of fluid resin was somewhat lower than of self-curing resin. This may be because the cracks, which are occured on the surface of non-cross-linked adherent resin by contact with abundant MMA of fluid resin, work as defects to decrease the adhesive strength.

Acrylic Resins↗
PubMed1978

Muscle strengths in relation to fat storage rate in young men.

Hand-grip strength, elbow flexion strength, trunk extension strength and knee extension strength, and body composition (measured by densitometry) were measured in 59 male students (mean 19.2 years) in order to compare the muscle strength of obese men, in relation to fat storage rate (% fat), with those of non-obese men. Their % fat ranged from 6.2-35.6%. Correlations of body weight and lean body mass were found to be significant with each muscle strength. Our findings presented that obese men had lower muscle strengths for body weight and lean body mass than non-obese men do. This might be the result of two characteristics, inactivity and weak willpower, of obese men. Besides, the 20% fat of threshold of obesity for men proposed by Behnke and Wilmore was reasonable from the viewpoint of the muscle strength because of the differences between group D (18.8% fat) and group E (23.8% fat).

Adipose Tissue↗
PubMed1977

Factors relating to the strength of male adolescents.

Factors relating to the strength of 53 postpubertal adolescent males have been examined. A strength index, composed of left and right handgrip and back strengths, was related to the following: anthropometric measurements and their derivatives; level of habitual activity; body shape as characterized by Heath-Carter and Sheldonian somatotype ratings; and anthropometric ratios. Strength was found to be positively related to all anthropometric measurements with the exception of skinfold thicknesses. When body weight was held constant, strength was positively related to arm circumference, bicondylar diameters of the humerus and femur, thigh volume, and biacromial diameter, and negatively related to percentage of fat. Strength was not related to the level of habitual activity. The relative contributions of overall body size and body shape to predictions of strength are approximately 57 and 47%. Measures of overall size appear to make no independent contribution to strength, beyond that contributed by limb segment volumes, or a combination of linear limb dimensions and measures of body shape.

Adolescent↗
PubMed2026

Handgrip strength and risk of common infections and sepsis: Two prospective cohorts with proteomic mediation analysis.

BACKGROUND: Recent evidence links adiposity with the risk of severe infections, but whether muscle strength may also be an independent risk factor is less studied. We investigated the association between handgrip strength and risk of common infections and sepsis and explored potential mediation by plasma proteomic biomarkers. METHODS: We analyzed data from 405,451 UK Biobank participants and replicated the main findings in 4474 Chinese adults from the Hong Kong Osteoporosis Study (HKOS). Baseline handgrip strength was measured by a dynamometer. Cox models were used to estimate its association with incidence of pneumonia, urinary tract infection (UTI), skin infection, and sepsis, adjusting for sociodemographic, lifestyle, and health-related factors. Mediation analyses were performed using 2912 plasma proteins in a UK Biobank subsample (n = 42,414) to identify biological pathways. RESULTS: In UK Biobank (median follow-up 13.6-15.3 years), lower handgrip strength was associated with significantly increased risk of pneumonia (hazard ratio per 5-kg decrement=1.10; 95% CI=1.09-1.11), UTI (1.10; 1.09-1.11), skin infection (1.05; 1.04-1.05), and sepsis (1.08; 1.07-1.10). Associations were largely consistent in HKOS, and the relative risks associated with low grip strength were generally most pronounced in underweight individuals. GDF15 and PLAUR were identified as the most important proteins which mediated 12-14% of these associations. CONCLUSION: Low handgrip strength is associated with increased risks of common infections and sepsis, particularly in underweight individuals, with partial mediation by proteins related to inflammation and immune-related pathways. Handgrip strength assessment may provide prognostic value beyond body mass index for clinical risk stratification.

Humans↗
PubMed1977

Bond strength studies of precious, semiprecious, and nonprecious ceramic-metal alloys with two porcelains.

One-hundred cylindrical pull-through ceramic-metal test specimens were subjected to shear loading forces. Two porcelain systems were treated in association with five ceramic alloys--one precious, one semiprecious, and three nonprecious alloys. 1. There was no significant difference in bond strength between Ceramco and Vita porcelains. 2. The various alloys tested demonstrated significantly different bond strengths. 3. Differential statistical tests suggested that nonprecious alloys performed better with Ceramco porcelain than with Vita porcelain. 4. The bond strength of Ceramco porcelain fused to nonprecious alloy N-C2 was significantly greater than that of Ceramic and traditional gold-based alloys. 5. Nonprecious alloy N-C1 produced significantly less bond strength than the traditional gold-based alloys. 6. Semiprecious alloy W produced high bond strengths with both Ceramco and Vita porcelains. 7. The cylindrical pull-through test was a reliable, reproducible method of testing ceramic-metal bond shear strength. 8. The surface roughness appears to be the one common factor in nonprecious alloys that relates to large differences in bond strength. Additional tests must be made to verify this hypothesis.

Ceramics↗