Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Torque”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 469 records · Page 26Linked to original sources
PubMed2000

Direct pelletization in a rotary processor controlled by torque measurements. II: effects of changes in the content of microcrystalline cellulose.

In the present study we investigated the effect of changes in the content of microcrystalline cellulose (MCC) on a direct pelletization process in a rotary processor in which the liquid addition was terminated once a certain increase in torque was produced. Nine different mixtures of MCC and lactose with MCC contents varying from 10% to 100% (w/w) were pelletized using 6 different torque increase levels, and the changes in pellet characteristics were investigated. The pellet characteristics investigated were pellet shape, size, and size distribution as well as the water content of the pellets at the end of liquid addition. To produce spherical agglomerates with suitable characteristics in a reproducible way, a content of at least 20% (w/w) MCC was found necessary. Linear correlations were found between the MCC content and the water content and between the torque increase and the water content, showing that the torque increase is suitable to control the process. A higher torque increase or a higher MCC content was found to increase the water content independently of each other.

Cellulose↗
PubMed2006

Keyswitch orientation can reduce finger joint torques during tapping on a computer keyswitch.

OBJECTIVE: To examine the effects of keyswitch orientation on joint torques. BACKGROUND: The fingertip produces primarily vertical forces during single-finger tapping on a computer keyswitch. However, horizontal force components within the sagittal plane of the finger could reduce net joint torques. METHOD: Eleven participants tapped on a keyswitch oriented in three directions: vertical, tilted 30 degrees such that when pressed it moved away from the user (similar to a positive-tilt keyboard), and tilted 30 degrees such that when pressed it moved toward the user (similar to a negative-tilt keyboard). Participants also tapped on a prototype cantilever keyswitch design in which the key cap moves along the arc of a bending beam gradually away from the user. Miniature electro-optical goniometers measured the finger posture, and a two-axis force sensor measured fingertip forces. RESULTS: Tapping on a keyswitch oriented such that it moves away from the user when pressed reduced net joint torques by 47% relative to tapping on a vertically orientated keyswitch and by 56% relative to tapping on a keyswitch oriented toward the user, whereas the cantilever design resulted in 14% decreases in net joint torque relative to the vertical orientation. CONCLUSION: Reductions of torques resulted from decreasing the moment arm of the fingertip force about the joints. APPLICATION: Keyboard design should incorporate keyswitch mechanism angles along with other postural and geometric constraints to reduce exposure of the finger joints and muscles to force during typing.

Adult↗
PubMed2003

Effect of knee position on hip and knee torques during the barbell squat.

UNLABELLED: Some recommendations suggest keeping the shank as vertical as possible during the barbell squat, thus keeping the knees from moving past the toes. This study examined joint kinetics occurring when forward displacement of the knees is restricted vs. when such movement is not restricted. Seven weight-trained men (mean +/- SD; age = 27.9 +/- 5.2 years) were videotaped while performing 2 variations of parallel barbell squats (barbell load = body weight). Either the knees were permitted to move anteriorly past the toes (unrestricted) or a wooden barrier prevented the knees from moving anteriorly past the toes (restricted). Differences resulted between static knee and hip torques for both types of squat as well as when both squat variations were compared with each other (p < 0.05). For the unrestricted squat, knee torque (N.m; mean +/- SD) = 150.1 +/- 50.8 and hip torque = 28.2 +/- 65.0. For the restricted squat, knee torque = 117.3 +/- 34.2 and hip torque = 302.7 +/- 71.2. Restricted squats also produced more anterior lean of the trunk and shank and a greater internal angle at the knees and ankles. The squat technique used can affect the distribution of forces between the knees and hips and on the kinematic properties of the exercise. PRACTICAL APPLICATIONS: Although restricting forward movement of the knees may minimize stress on the knees, it is likely that forces are inappropriately transferred to the hips and low-back region. Thus, appropriate joint loading during this exercise may require the knees to move slightly past the toes.

Adult↗
PubMed2006

Low flagellar motor torque and high swimming efficiency of Caulobacter crescentus swarmer cells.

We determined the torque of the flagellar motor of Caulobacter crescentus for different motor rotation rates by measuring the rotation rate and swimming speed of the cell body and found it to be remarkably different from that of other bacteria, such as Escherichia coli and Vibrio alginolyticus. The average stall torque of the Caulobacter flagellar motor was approximately 350 pN nm, much smaller than the values of the other bacteria measured. Furthermore, the torque of the motor remained constant in the range of rotation rates up to those of freely swimming cells. In contrast, the torque of a freely swimming cell for V. alginolyticus is typically approximately 20% of the stall torque. We derive from these results that the C. crescentus swarmer cells swim more efficiently than both E. coli and V. alginolyticus. Our findings suggest that C. crescentus is optimally adapted to low nutrient aquatic environments.

Biomechanical Phenomena↗
PubMed1999

Effect of a static calf-stretching exercise on the resistive torque during passive ankle dorsiflexion in healthy subjects.

STUDY DESIGN: A within-subject experimental design was used with to measure the effect of calf-stretching exercises on the resistive torque during passive ankle dorsiflexion in a group of 20 healthy men (aged 21 to 40). OBJECTIVES: The purpose of this study was to determine if the performance of calf-stretching exercises would produce a decrease in resistive torque during passive ankle dorsiflexion. BACKGROUND: Calf-stretching exercises are widely used in sporting, fitness, and rehabilitation settings yet the effects of stretching on the passive mechanics of the ankle joint are not well understood. METHODS AND MEASURES: A KIN-COM isokinetic dynamometer was used to measure the passive resistive torque of the ankle while the joint complex was moved through return cycles from 10 degrees plantarflexion to 10 degrees dorsiflexion at a constant velocity of 6 degrees/s. Each subject's right or left ankle was randomly assigned to either a control or an experimental condition. The latter underwent a total of 4 static stretches, each lasting 30 seconds. RESULTS: The main findings of the study were that the calf-stretching exercises did not produce a significant reduction in the resistive torque during ankle dorsiflexion, as measured by the peak to peak torque at 10 degrees of ankle dorsiflexion or in the center range of the hysteresis loop at 0 degree dorsiflexion. CONCLUSION: Static calf-stretching exercises of short duration did not reduce the passive resistance of the connective tissue within the surrounding muscle and joint structures in the ankles of healthy young men.

Adult↗
PubMed2002

Effect of rotator cuff exercise on humeral rotation torque in healthy individuals.

Conservative management of rotator cuff pathology often involves certain therapeutic exercises. Although a major goal of these exercises is to increase strength of the rotator cuff, little empirical evidence supports this assertion. In this study, 34 nonpathologic young adults were pretested using a LIDO Multijoint II isokinetic device for average and peak torque generated during internal and external rotation. Subjects were arbitrarily assigned to a right-arm- or left-arm-trained group, exercised for 4 weeks, and then posttested for changes in humeral rotation torque. Moderate but significant increases in torque (8-10%) as well as in total work done were observed in both groups, only in the trained arm. Subjects who trained the nondominant (left) arm experienced gains similar to those who trained the right arm. Gains were significant in the case of both internal and external rotation (also average as well as peak torque), with men and women experiencing the same relative increases. These data, in addition to supporting the use of selected exercises to increase humeral rotation torque in a healthy population, offer a potential model for the rehabilitation of patients with rotator cuff injury.

Adult↗
PubMed2002

[Torque of endosseous dental screw type implants].

The success of osseous and oral implants is partially dependent on the design and on the mechanical way of insertion. The torque moments during manual and machine-insertion and the correlation between torque and design of the implants were topics of this paper. The experiments were separated in two parts using pork-ribs in vitro. The first experiment was done with manual and machine insertion of implants. The second trial dealt with machine overloading of correctly inserted implants. The cylindrical implants showed an initial insertion curve followed by a linear phase which ended in a peak when insertion depth was reached. The conical formed implants did not show an initial curve while being inserted but a steeper linear phase and a defined peak when reaching the insertion depth. The torque moments at deep insertion (normal drilling depth) differed about 80% to the torque moments at normal insertion. The torques of continual machine insertion are 15 to 20% lower than those of discontinual manual insertion. According to these findings the design parameters for an optimal enossal oral dental implant should be of a cylindrical form with step like design, a cylindrical neck and a self cutting function of the symmetrical thread in combination with a blunt implant tip.

Animals↗
PubMed2003

Men's shoes and knee joint torques relevant to the development and progression of knee osteoarthritis.

OBJECTIVE: To determine if men's dress shoes and sneakers increase knee joint torques and play the same role in the development and/or progression of knee osteoarthritis (OA) as women's high-heeled dress shoes. METHODS: Three-dimensional data regarding lower extremity torques and motion were collected during walking in 22 healthy men while (1) wearing dress shoes, (2) wearing sneakers, and (3) barefoot. Data were plotted and qualitatively compared; major peak values were statistically compared between conditions. RESULTS: The external knee varus torque in early stance was slightly greater with the dress shoes and sneakers, but this slight increase can be explained by the faster walking speed with shoes. No significant increases were found in any other of the sagittal, coronal, or transverse knee torques when walking with dress shoes and sneakers compared to barefoot. CONCLUSION: Men's dress shoes and sneakers do not significantly affect knee joint torques that may have relevance to the development and/or progression of knee OA.

Adult↗
PubMedDate not supplied

Relationships between head fixation pins for radiosurgery and the skull bone--usefulness of a torque wrench.

BACKGROUND: In stereotactic radiosurgery (SRS), fixation devices are secured to the patient's head with pins. However, there have been no standards for the use of such pins, which must be inserted with appropriate torque based on the surgeon's clinical judgment. Therefore, the pins may sometimes be tightened excessively and penetrate too deeply into the patient's skull. PURPOSE: To improve safety in SRS, a torque wrench was used for pin insertion. The usefulness of the torque wrench was then evaluated by examining the relationships between the pins and skull bone and identifying differences according to the wrench used and the patient's bone thickness. METHODS: CT images of patients who had previously undergone SRS were used to assess the relationships between the pins and skull bone. Differences according to the wrench used and pin insertion site were investigated. RESULTS: Compared with a standard wrench, use of the torque wrench decreased the insertion depth of pins in the skull bone. In terms of site, pins in the forehead were inserted more deeply. No differences related to the frontal sinus were observed. CONCLUSION: The use of a torque wrench improved safety during pin insertion for SRS procedures.

Adolescent↗
PubMed2003

Isokinetic peak torque and hamstring/quadriceps ratios in young basketball players. Effects of age, velocity, and contraction mode.

AIM: The purpose of this study was to provide an extensive isokinetic profile, including peak torque and "functional" and "conventional" muscle group ratios, of basketball players throughout the developmental years 12-17. Furthermore, we investigated the effects of age and angular velocity on peak torque and reciprocal muscle group ratios, and observed the force-velocity pattern. METHODS: Basketball players (n=180) 12 to 17 years. were divided according to their age in 6 equal (n=30) groups aged 12, 13, 14, 15, 16, 17 years. All subjects performed maximum knee extension and flexion efforts at 60 inverted exclamation mark /s and 180 inverted exclamation mark /s angular velocities under eccentric and concentric conditions. The absolute (Nm) peak torque was measured, and the relative peak torque (PT/BW) and "functional" and "conventional" reciprocal muscle group ratio (%) were calculated. RESULTS: PT/BW values of knee flexors ranged from 0.98 to 2.29 Nm/kg and of extensors from 1.53 to 3.69 Nm/kg, across all age, velocity, and muscle action levels. PT/BW was higher at slow speed and during eccentric contraction irrespective of age and angular velocity/muscle action. The results indicated a significant (p<0.05) age-related increase in peak torque independent of changes in BW. The force-velocity patterns were similar across ages. The "functional" and "conventional" ratios were not affected by age, but increased with increase in angular velocity, except the CON(KF)/ECC(KE) ratio that was higher (p<0.05) at slow speed. CONCLUSION: The present study provides an extensive isokinetic profile of a knee joint in basketball players throughout developmental years 12-17. Coaches and physical therapist may use these information when evaluating and planning exercise programs during training and rehabilitation.

Adolescent↗
PubMedDate not supplied

Angle- and velocity-specific alterations in torque and semg activity of the quadriceps and hamstrings during isokinetic extension-flexion movements.

The purpose of this study was to investigate the effect of movement velocity (100 degrees, 200 degrees , 300 degrees s(-1), and 400 degrees s(-1)) and joint position (0 degrees - 15 degrees [L0], 25 degrees - 40 degees [L25], 55 degrees - 70 degrees [L55], and 75 degrees - 90 degrees [L75]) on peak torque (PT) parameters and surface electromyography (SEMG) of the knee-joint muscles during reciprocal isokinetic extension and flexion movements. Thirteen subjects (age = 22.7 +/- 2.1 years, mean height = 161.1 +/- 6.6 cm, mean weight = 63.5 +/- 5.8 kg) participated in the study. Bipolar surface electrodes were placed over the vastus medialis, vastus lateralis, biceps femoris, and medial hamstrings for determination of the root mean square (SEMGrms) and median frequency (SEMGmf) of the SEMG. Peak torque, angle of peak torque (PTang), percentage of peak torque (PTper), SEMGrms, and SEMGmf were analyzed using separate repeated measures analysis of variance (ANOVA). The following main results, significant at p < or = 0.05 or better, were found: The PTang was influenced by movement velocity (in extension there was a decrease in PTang moving from 300 degrees x s(-1) to 400 degrees x s(-1) and inflexion there was an increase in PTang moving from 300 degrees x s(-1) to 400 degrees x s(-1)). Secondly, a greater percentage of peak torque (PTper) was maintained during knee flexion than knee extension. And thirdly, both the quadriceps and hamstrings exhibited changing amplitudes and spectral frequencies based on joint position and movement velocity. There was a trend of decreasing SEMGrms for the quadriceps as the knee moved into extension, and a lower SEMGmf during early (L75) and end stages of knee extension (L0). For the hamstrings, SEMGrms was lowest at the more shortened position (L75) and highest near the mid-position (L25); the lowest SEMGmf occurred at the more lengthened position (L0) and the highest occurred at the more shortened position (L75). Finally, velocity influenced hamstrings and quadriceps muscle amplitude such that SEMGrms was highest at the slower velocities and lowest at the higher velocities. Velocity had no impact on quadriceps spectral properties (p > 0.05), but had a cyclic effect on hamstrings spectral properties. Changes in amplitude and frequency spectrum in tested muscles could be explained, in part, by neural drive to these muscles. Data support the hypothesis of lower activation levels of the quadriceps muscle in the extended position espoused by several authors as a way to protect the knee-joint in the knee-extended position.

Adult↗
PubMed1983

A longitudinal analysis of torque and its relationship to achievement and educational classification among normal, disturbed, and learning-disabled children.

Torque (clockwise circlings with either hand on a visual-motor task) has been shown to be related to a variety of academic, personal, and adjustment difficulties (Blau, 1977b). A longitudinal analysis was conducted for 948 third-grade students, selected randomly from various special and nonspecial education programs from a large, urban/suburban school system. Current measures of achievement, grade retention, and special education categorization were related to torque data obtained 4 years previously. Only grade retention was found to differ significantly between the torque and no torque groups. While the overall findings indicate no clear relationship between torque and various academic variables, some significant findings and trends in the data warrant further investigation.

Achievement↗
PubMed1996

Optimization of torque-balanced asymmetric head gradient coils.

Local gradient coils can improve the performance of echo-planar, diffusion, and short TE imaging in the brain. A modified singular value decomposition algorithm, which allows the rapid optimization and comparison of designs, was employed to optimize head size gradient coils. A theoretical expression for the torque on a cylindrical coil is presented and used to design coils that are free from torque while pulsed within a magnetic field. Gradient coils of various lengths both with and without torque constraints were compared; although torque-free coils do not perform as well as unbalanced coils, asymmetric torque-balanced coils can achieve comparable homogeneity with only a modest increase in inductance and resistance. Both types of coils outperform body size gradient coils by a dramatic margin. A three-axis head gradient designed using these techniques was constructed and used for brain imaging on a clinical scanner.

Brain↗
PubMed1997

Charged residues of the rotor protein FliG essential for torque generation in the flagellar motor of Escherichia coli.

The FliG protein of Escherichia coli is essential for assembly and function of the flagellar motor. Certain mutations in FliG give a non-motile, or Mot-, phenotype, in which flagella are assembled but do not rotate. Mutations with this property are clustered in a C-terminal segment of FliG that is stable when expressed alone, and thus probably constitutes an independently folded domain. Previously, we suggested that this domain forms the rotor portion of the active site for torque generation in the motor. In this work, we have used a mutational approach to identify the amino acid residues in the C-terminal domain of FliG that are most important for motor function. Site-directed mutagenesis was used to replace each of the conserved residues in this domain with alanine, and the effects on motor function were measured. Because charged residues have often been suggested to have important roles in torque generation, conserved charged residues were changed individually and in all pairwise combinations. The results show that three charged residues of FliG, Arg279, Asp286 and Asp287, are directly involved in torque generation. Mutations in these residues cause motility defects that suggest that they function jointly, in an active site whose most important property is a specific arrangement of charges. Two other charged residues, Lys262 and Arg295, may also be involved in torque generation, but are less critical than Arg279, Asp286 or Asp287. Unchanged residues of the FliG motility domain do not appear to have direct roles in torque generation, although some are needed for the stability of the protein or for normal clockwise/ counter-clockwise switching. The Mot- mutations of fliG isolated previously by random mutagenesis do not alter the putative active-site residues, but render the proteins abnormally susceptible to proteolysis, suggesting significantly altered conformations or reduced stabilities.

Bacterial Proteins↗
PubMed1991

Effects of torque disturbances on elbow joint movements evoked in unanesthetized cats by microstimulation of the motor cortex.

Flexion and extension movements were evoked in the elbow joint of unanesthetized cats by intracortical microstimulation (ICMS) applied to deep layers of the motor cortex (areas 4 and 6). Pulse trains with duration up to 3-4 s, current intensities of 15-50 microA and rates of approximately 100/s were used. Cortically evoked movements (CEMs) were tested mechanically by applying servo-controlled torque disturbances to the joint. The disturbances consisted of two reciprocating sinusoidal pulses of torque with fixed frequencies (1.2 or 3.2 Hz). A pronounced torque-angle hysteresis with long-lasting after-effects was revealed in the presence of the torque disturbances that opposed the CEMs and/or assisted them. Two parameters were introduced to describe the mechanical testing of the CEMs quantitatively: (1) the resulting stiffness (RS) defined during the forward and reverse phases of the disturbed movement as a ratio between the amplitudes of torque wave and the overall change of angle at these phases; (2) uncertainty index (UI) defined as the subtraction of forward and reverse angle changes, which was normalized by the first of these two values. RS was shown to be dependent on the immediate past movement history of the joint, it increased with changes in the direction of movement, and its magnitude during such changes could be several times higher than when the disturbance was in the same direction as the movement.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

A comparison of voluntary and electrically evoked isokinetic plantar flexor torque in males.

The angle-specific isokinetic torque- and power-velocity relationships of the triceps surae were examined in ten male sprint athletes aged [mean (SD)] 22.4 (3.2) years, ten non-trained adult men aged 27.4 (4.8) years and six elderly male subjects aged 68.5 (2.4) years. Normal voluntary contractions were compared with those obtained using maximal tetanic stimulation and a release technique which standardised the level of muscle activation during isokinetic contractions. When the isokinetic data was normalized to the maximum isometric torque the stimulated release contractions at 5.18-5.29 rad.s-1 produced significantly (P < 0.05) greater torque than the voluntary no-release contractions at the same angular velocity in each group of subjects. The three subject groups generated their peak power at 3.07 rad.s-1 during the voluntary no release contractions. However, with the stimulated release contractions, power had still not reached a peak at 5.29 rad.s-1, the highest angular velocity that could be tested. It appears that at higher angular velocities the triceps surae is capable of greater torque and power generation when contractions are evoked using a stimulated release technique. It is suggested that the stimulated release technique gives a more complete picture of the torque-velocity characteristics of the contractile component of the triceps surae.

Adult↗
PubMed1991

The effect of range of motion and isometric pre-activation on isokinetic torques.

The effect of an increased angle of excursion and isometric pre-activation on isokinetic torques of knee extensors was investigated in five male subjects, mean age 35.0 years, SD 9.6. Peak torque and isoangular torque at 0.52 rad from full knee extension (FKE) were measured when contractions were carried out at 3.14, 4.19 and 5.24 rad.s-1 starting: 1) from a standard knee angle (SA) of 1.57 rad from FKE, 2) from the same starting angle as SA, plus an isometric preload (P) equivalent to 25% of isometric maximal voluntary contraction and 3) from an increased angle of knee flexion (IA), 2.09 rad from FKE plus P. Surface integrated electromyograms (iEMG) of the vastus lateralis muscle in SA and IA + P were also recorded. The IA + P had the effect of increasing peak torque, as compared to SA, on average by 12.0%, SD 7.5% (P less than 0.001) at 3.14 rad.s-1, 19.5%, SD 5.5% (P less than 0.001) at 4.19 rad.s-1, 21.6%, SD 10.7% (P less than 0.001) at 5.24 rad.s-1 and of increasing mean iEMG by 15.7%, SD 7.0% (P less than 0.001) at 5.24 rad.s-1. The IA + P also had the effect of increasing the angle from FKE at which peak torque occurred: from means of 0.80 rad, SD 0.11 to 1.00 rad, SD 0.07 at 3.14 rad.s-1, from 0.65 rad, SD 0.11 to 0.92 rad, SD 0.09 at 4.19 rad.s-1 and from 0.60 rad, SD 0.11 to 0.88 rad, SD 0.11 at 5.24 rad.s-1 (P less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Torque, lateral preference, and cognitive ability in primary-grade children.

It has been suggested that torque, the tendency to draw circles in the clockwise direction, is related to left-handedness and is a marker for psychopathology. Results of recent studies conflict with this hypothesis but are weakened by imprecise definition and unreliable assessment of torque. Measures of torque, lateral preference, and cognitive ability were administered to 181 children in kindergarten and first grade. As reported previously, rate of torque decreased with age and was greater among males. Children with complete clockwise or counter-clockwise circling at both assessments differed in pattern but not in overall level of cognitive ability. No differences were found in strength, direction, or concordance of hand and foot preference. Results of this and other studies are seen as inconsistent with proposals that torque is symptomatic of psychopathology.

Art↗