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At least 1,099 records · Page 61Linked to original sources
PubMed1993

The effect of stabilization on isokinetic knee extension and flexion torque production.

The purpose of this study was to examine the effect of four methods of stabilization on maximal reciprocal isokinetic knee extension and flexion. Left knee extension/flexion was tested at 60 degrees /s in 20 subjects. Warm-up consisted of five submaximal and one maximal effort followed by three maximal efforts in each of four randomized stabilization conditions: 1) Hands and back stabilization; the trunk was strapped to the back rest and the hands grasped the seat. 2) Back stabilization; the trunk was strapped to the back rest and the hands were folded across the chest. 3) Hand stabilization; the hands grasped the seat and the back rest was removed. 4) No stabilization; the hands were folded across the chest and the back rest was removed. One-way repeated measures ANOVA showed a significant effect of stabilization for knee extension (F(3,57)=17.44, p=.0001) and knee flexion (F(3,57)= 5.37, p=.002). Paired, two-tailed student's t-tests with Bonferroni correction showed that, in knee extension, no stabilization was significantly less than all others, p<.001. In addition, back stabilization was less than hands and back stabilization, p<.005. In knee flexion, no stabilization was significantly less than all others, p<.01. In conclusion, the method of trunk stabilization significantly affected maximal reciprocal isokinetic knee extension/flexion strength measurements. Maximal knee extension/flexion torque production was achieved when the trunk was strapped to the back support and when the hands grasped the seat.

Journal Article↗
PubMed1991

A removal torque and histomorphometric study of bone tissue reactions to commercially pure titanium and Vitallium implants.

Screw-shaped commercially pure (CP) titanium and Vitallium implants were inserted in the rabbit tibial metaphysis. After a healing period of 3 months, it was demonstrated that a higher torque was needed to remove the CP titanium implants (average 24.9 Ncm) compared to Vitallium implants (average 11.7 Ncm). The histomorphometric part of the study revealed more bone-to-metal contact for the CP titanium implants (average 34.7%) compared to the Vitallium implants (average 21.7%). The results obtained in this study could be explained by differences in the topography or in biocompatibility of the metals, or a combination of these two factors.

Animals↗
PubMed1990

The effect of sports training on the age-related changes of body composition and isokinetic peak torque in knee extensors of junior speed skaters.

To elucidate the effect of sports training on age-related changes of body composition and isokinetic peak torque (IPT) in knee extensors, junior speed skaters were tested in comparison with relatively sedentary age-matched controls. Subjects consisted of 132 male and 71 female junior speed skaters (SSs; aged 10-18 years). Two-hundred and thirty-six males and 265 females between the ages of 10 to 18 in the same geographic area were also tested as controls (Cs). Lean Body Mass (LBM) and relative body fat (%) were estimated from skinfolds, using the equations for preadolescent boys and girls. An isokinetic dynamometer (Cybex II) was used to measure IPT (Nm) produced at angular velocities corresponding to 0, 30, 180, 300 deg.sec-1 during maximal knee extensions. SSs were heavier in body weight and LBM from age 13 for males and from age 16 for females than the Cs, and there were significant differences in LBM between SSs and Cs after age 16 regardless of sex. The female Cs showed a gradual increase in relative body fat (%) after age 14, however, such a trend was absent in female SSs. IPT increased in any angular velocity with age from 10-18 years in the male Cs, and from 10-15 years in the female Cs. On the other hand, male SSs tended to be stronger after age 13 and female SSs stronger after age 16. Significant differences between the two groups were obtained only at lower angular velocities from 16 years of age in both sexes.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

[Torque effect of the forces on the terminal abutment in Kennedy Class II cases].

In this research we have compared the properties of force distribution of some retainers which are used in Kennedy Class II modification 1 cases by using photoelastic stress analysis technique. This research has shown that different retainers vary in their ability to reduce stress to abutments. The results showed that the stressbreaker reduced torque to the abutment teeth induced by the denture and contributed to the preservation of the teeth and their supporting structures. When rigid retainers are used, splinting of the distal abutments on the free-end side and restoring of the abutments on the tooth supported side are usually indicated.

Dental Abutments↗
PubMed1989

A wheelchair ergometer with a device for isokinetic torque measurement.

A wheelchair ergometer has been developed for the study of wheelchair work. At each propulsion the peak torque can be examined, and there is an opportunity to directly study angular amplitude, power output, work etc. The physical capacity of the subject as well as the importance of chair adjustments upon performance can be evaluated.

Equipment Design↗
PubMed1989

[Torque measurement of self-threading bone screws. Test procedure for new surgical screws].

Different systems of self-cutting screws are tested by a measuring instrument to test the torsional strain. Modern methods of measuring techniques are applied to get results of the torsional force and the torque by screwing into the bones. To get a self-cutting screw system several methods of biomechanical properties must be applied. A variety of quality tests, of biomechanical screws, are used, before performing the operations, that flaws may be detected.

Bone Screws↗
PubMed1989

[Slowing of turbine under different pressures (torque)].

A comparative examination of in vivo measured revolutions proves that turbines with torque have a 100% wider usable revolution band than conventional ones. The resulting increased grinding capacity may seen at first sight as a positive effect, but is combined with a more than proportional increasing heat development. Literature, research and own considerations allow the statement, that revolutions used today and the possible pressures make a sufficient cooling of the grinded surface a problem. In order to reduce the recent distinct increase of preparation damages, a reduction of the possible exerted pressure as well as the current level of revolutions must be called for. In the same way as usual in the production industry the optimum rate of grinding capacity to heat development should be determined for each grinding instrument. In this respect not only the turbine is a step into a wrong direction.

Dental Cavity Preparation↗
PubMed1985

Isometric torque of the quadriceps femoris after concentric, eccentric and isometric training.

Twenty-seven normal, healthy women participated in this study, which investigated three methods of increasing the isometric strength of the quadriceps femoris through a six-week training program. Three experimental exercise groups were formed: A, eccentric, B, concentric, and C, isometric. The peak isometric torque of the quadriceps femoris was determined on the Cybex II Isokinetic Dynamometer before and after training. A total of 18 exercise sessions per subject were held. A two-way ANOVA with repeated measures revealed that while all three experimental groups significantly increased in isometric strength, no one method of training was superior. No interaction occurred in the population between the effects of pre- and posttraining scores and the type of training. The relationship between the experimental design and knee joint biomechanics may have precluded significant differences in strength gain among the experimental groups.

Adult↗
PubMedDate not supplied

An experimental model to measure the torque of pin insertion and extraction for external fixation.

An original system used to measure torque of pin insertion and extraction in external fixation is presented. The system is made up of an electronic dynamometric key and an analogic/digital switchboard that may be linked up to a personal computer. The in vitro results show the simplicity of use and the versatility of the system, that is capable of providing the surgeon with accurate indicative values as to the mechanical resistance of the bone-pin interface during implantation of any fixator.

Biomechanical Phenomena↗
PubMed1995

Torque generation by the flagellar rotary motor.

A review is given of the structure and dynamics of the flagellar rotary motor. Force-generating elements in a motor driving a tethered bacterium (a cell fixed to the substratum by a single flagellum) exert forces of order 20 pN while moving at speeds of order 1 micron/s. Force-generating elements in a motor driving a flagellar filament in a bundle exert forces some 10-fold lower but move at speeds more than 10-fold higher. The motor torque-speed relationship has been measured over a wide dynamic range. Motors strongly resist being driven backwards and are easily broken.

Bacterial Proteins↗
PubMedDate not supplied

Forearm pronation and supination: reliability of absolute torques and nondominant/dominant ratios.

This study examined the reliability of pronation and supination measurements expressed in absolute units (newton-meters [Nm]) and nondominant/dominant ratios (%), and determined isometrically using the BTE (WS20) and the Cybex (340) dynamometers. Twenty-one healthy men and 22 healthy women were tested twice on each machine, within 14 days. Twelve of 16 reliability coefficients for absolute torques were considered acceptable (> 0.75) when determined as the reliability of two repetitions on one occasion, while 14 of 16 coefficients were acceptable when determined as the reliability of two repetitions on each of two occasions. However, reliability coefficients for the nondominant/dominant ratios were not acceptable on one (0 of 8 coefficients > 0.75) or two (2 of 8 coefficients > 0.75) occasions. Ratio data were also characterized by larger standard errors of measurement (SEMs) and wider 95% confidence intervals, relative to the sample mean and standard deviation. Overall, reliability coefficients, SEMs, and 95% confidence intervals were similar for men and women, pronation and supination movements, and the BTE and Cybex dynamometers. The authors suggest that absolute scores be used when possible, as these data tend to provide more reliable measurements--especially when the clinician has only limited test occasions to establish baseline scores.

Bias↗
PubMed2006

Gender differences in hip adduction motion and torque during a single-leg agility maneuver.

The purpose of this study was to identify gender differences in hip motion and kinetics during a single leg bidirectional deceleration maneuver. The rationale for the development of this maneuver was to test dynamic hip control during the deceleration of three different types of single-leg landings. The hypothesis was that female athletes would display increased hip adduction angles and moments during the maneuver compared to male athletes. Thirty-six collegiate soccer players (19 female, 17 male) volunteered to participate. Subjects were instructed to start the maneuver balancing on one foot, to hop through an agility-speed ladder on the same leg "up two boxes, back one, and then up one and hold it." Hip kinematics and kinetics during all three landings were examined. Females demonstrated significantly greater hip adduction angles at initial contact during all three landings and greater maximal hip adduction during landings 1 and 2 compared to male athletes. Females also exhibited significantly increased external hip adduction moments during landing 1, however, no differences were found between genders during landings 2 and 3.

Adult↗
PubMed2003

Eccentric exercise, isokinetic muscle torque and delayed onset muscle soreness: the role of reactive oxygen species.

There is growing evidence that reactive oxygen species (ROS) are involved in the muscular damage and soreness that is observed following strenuous or unaccustomed exercise. This study investigated the relationship between delayed onset muscle soreness (DOMS), muscle function and ROS following downhill running using electron spin resonance (ESR) spectroscopy and plasma malonaldehyde (MDA) concentrations. Eight physically active male subjects participated in two trials consisting of 30 min of running at approximately 65% VO(2max) on the flat (FLA) or a 15% downhill (DWN) gradient. Venous blood samples were drawn before, immediately after, and then 24, 48 and 72 h post exercise, and at the same time DOMS and muscle function were assessed. Blood was analysed for markers of ROS, total and differential white blood cell count, and creatine kinase. Muscle function was measured on an isokinetic dynamometer, whilst DOMS was assessed using a visual analogue scale. An increase in ROS, detected via ESR spectroscopy and MDA, was observed following DWN ( P<0.05) but not following FLA. Increased DOMS and loss of muscle function were observed following DWN ( P<0.05) but not following FLA ( P>0.05). DWN resulted in a transient leukocytosis ( P<0.05) occurring immediately post-exercise but returning to pre-exercise levels by 24 h. Although DWN resulted in an increase in ROS production, the increase occurred after the peak decline in muscle function and DOMS, suggesting that there may be a disassociation in the temporal relationship between ROS, loss of muscle function and DOMS.

Adult↗
PubMed2005

Charnley low-frictional torque arthroplasty for avascular necrosis of the femoral head.

Forty-nine patients (mean age, 37 years; 20-50 years) had had 69 Charnley low-frictional arthroplasties for avascular necrosis of the femoral head. Their mean follow-up was 13.4 years (2-25 years). Five patients (8 hips) had no continuing follow-up, 5 (8 hips) are known to have died, 6 (7 hips) had had a revision at a mean follow-up of 16.4 years (11-25 years): 6 for cup loosening and 1 for a fractured stem and a loose cup. The remaining 33 patients (46 hips) had an excellent clinical result with all stems remaining soundly fixed, but 6 cups were radiologically loose at a mean follow-up of 16 years and 4 months. Wear and cup loosening are the main problems limiting the survival of the arthroplasty.

Adult↗