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 865 records · Page 48Linked to original sources
PubMed2002

Task differences with the same load torque alter the endurance time of submaximal fatiguing contractions in humans.

Endurance time, muscle activation, and mean arterial pressure were measured during two types of submaximal fatiguing contractions that required each subject to exert the same net muscle torque in the two tasks. Sixteen men and women performed isometric contractions at 15% of the maximum voluntary contraction (MVC) force with the elbow flexor muscles, either by maintaining a constant force while pushing against a force transducer (force task) or by supporting an equivalent inertial load while maintaining a constant elbow angle (position task). The endurance time for the force task (1402 +/- 728 s) was twice as long as that for the position task (702 +/- 582 s, P < 0.05), despite a similar reduction in the load torque at exhaustion for each contraction. The rate of increase in average electromyographic activity (EMG, % peak MVC value) for the elbow flexor muscles was similar for the two tasks. However, the average EMG was greater at exhaustion for the force task (22.4 +/- 1.2%) compared with the position task (14.9 +/- 1.0%, P < 0.05). In contrast, the rates of increase in the mean arterial pressure, the rating of perceived exertion, anterior deltoid EMG, and fluctuations in motor output (force or acceleration) were greater for the position task compared with the force task (P < 0.05). Furthermore, the rate of bursts in EMG activity, which corresponded to the transient recruitment of motor units, was greater for the brachialis muscle during the position task. These results indicate that the briefer endurance time for the position task was associated with greater levels of excitatory and inhibitory input to the motor neurons compared with the force task.

Acceleration↗
PubMed2004

The effect of glycerol on torque, electromyography, and mechanomyography.

The purpose of this investigation was to determine the effect of hyperhydration on the electromyographic (EMG) and mechanomyographic (MMG) responses during isometric and isokinetic muscle actions of the biceps brachii. Eight (22.1 +/- 1.8 years, 79.5 +/- 22.8 kg) subjects were tested for maximal isometric, submaximal isometric, and maximal concentric isokinetic muscle strength in either a control (C) or hyperhydrated (H) state induced by glycerol ingestion while the EMG and MMG signals were recorded. Although fluid retention was significantly greater during the H protocol, the analyses indicated no change in torque, EMG amplitude, EMG mean power frequency (MPF), MMG amplitude, or MMG MPF with hyperhydration. These results indicated that glycerol-induced fluid retention does not affect the torque-producing capabilities of a muscle, the impulses (EMG) going to a muscle, or muscular vibrations (MMG). It has been suggested that EMG and MMG can be used as direct electrical/mechanical monitoring, which could be presented to trainers and athletes; however, before determining the utility of these signals, the MMG and EMG responses should be examined under a variety of conditions such as in the present study.

Adult↗
PubMed2006

Acute effects of static stretching on maximal eccentric torque production in women.

The purpose of this study was to examine the acute effects of static stretching on peak torque (PT) and the joint angle at PT during maximal, voluntary, eccentric isokinetic muscle actions of the leg extensors at 60 and 180 degrees x s(-1) for the stretched and unstretched limbs in women. Thirteen women (mean age +/- SD = 20.8 +/- 0.8 yr; weight +/- SD = 63.3 +/- 9.5 kg; height +/- SD = 165.9 +/- 7.9 cm) volunteered to perform separate maximal, voluntary, eccentric isokinetic muscle actions of the leg extensors with the dominant and nondominant limbs on a Cybex 6000 dynamometer at 60 and 180 degrees x s(-1). PT (Nm) and the joint angle at PT (degrees) were recorded by the dynamometer software. Following the initial isokinetic assessments, the dominant leg extensors were stretched (mean stretching time +/- SD = 21.2 +/- 2.0 minutes) using 1 unassisted and 3 assisted static stretching exercises. After the stretching (4.3 +/- 1.4 minutes), the isokinetic assessments were repeated. The statistical analyses indicated no changes (p > 0.05) from pre- to poststretching for PT or the joint angle at PT. These results indicated that static stretching did not affect PT or the joint angle at PT of the leg extensors during maximal, voluntary, eccentric isokinetic muscle actions at 60 and 180 degrees x s(-1) in the stretched or unstretched limbs in women. In conjunction with previous studies, these findings suggested that static stretching may affect torque production during concentric, but not eccentric, muscle actions.

Adult↗
PubMed2006

Effect of diameter of the drill hole on torque of screw insertion and pushout strength for headless tapered compression screws in simulated fractures of the lateral condyle of the equine third metacarpal bone.

OBJECTIVE: To compare variables for screw insertion, pushout strength, and failure modes for a headless tapered compression screw inserted in standard and oversize holes in a simulated lateral condylar fracture model. SAMPLE POPULATION: 6 pairs of third metacarpal bones from horse cadavers. PROCEDURE: Simulated lateral condylar fractures were created, reduced, and stabilized with a headless tapered compression screw by use of a standard or oversize hole. Torque, work, and time for drilling, tapping, and screw insertion were measured during site preparation and screw implantation. Axial load and displacement were measured during screw pushout. Effects of drill hole size on variables for screw insertion and screw pushout were assessed by use of Wilcoxon tests. RESULTS: Drill time was 59% greater for oversize holes than for standard holes. Variables for tapping (mean maximum torque, total work, positive work, and time) were 42%, 70%, 73%, and 58% less, respectively, for oversize holes, compared with standard holes. Variables for screw pushout testing (mean yield load, failure load, failure displacement, and failure energy) were 40%, 40%, 47%, and 71% less, respectively, for oversize holes, compared with standard holes. Screws could not be completely inserted in 1 standard and 2 oversize holes. CONCLUSIONS AND CLINICAL RELEVANCE: Enlarging the diameter of the drill hole facilitated tapping but decreased overall holding strength of screws. Therefore, holes with a standard diameter are recommended for implantation of variable pitch screws whenever possible. During implantation, care should be taken to ensure that screw threads follow tapped bone threads.

Animals↗
PubMed2006

Torque levels, subjective discomfort, and muscle activity associated with four commercially available screwdrivers under static and dynamic work conditions.

This study evaluated screwdrivers with different handle designs and blade lengths. 10 men and 10 women voluntarily participated. A repeated-measures experiment design was employed. The three independent factors were sex of user, handle (four types), and blade length (130, 170, and 210 mm). The dependent measures were the maximum supination torque under a static task and the %MVC of EMG responses in biceps brachii and flexor digitorum, and a discomfort rating for the upper extremity under the dynamic task. Analysis showed that the in-line screwdriver with the combined characteristics of large handle diameter (3.8-4.1 cm), smooth rubber covering handle surface, triangular (or circular) shape, and adequate handle length (11 cm) had the greatest supination torque and a smaller discomfort rating than the screwdriver with the pistol-grip handle. Blade length was not significantly related to any dependent measure.

Adult↗
PubMedDate not supplied

Removal torque and histomorphometric investigation of 4 different titanium surfaces: an experimental study in the rabbit tibia.

This study presents a histomorphometric and biomechanical comparison of bone response to commercially pure titanium screws with 4 different types of surface topographies placed in the tibial metaphysis of 12 rabbits. Each rabbit had 4 implants placed, 2 in each tibia. The 4 surface topographies were a machined surface, a grit-blasted surface, a plasma-sprayed surface, and an acid-etched (Osseotite) surface. After a healing period of 5 weeks, histomorphometric and removal torque data revealed a significantly higher percentage of bone-to-implant contact and removal torque for acid-etched implants compared to machined, blasted, and plasma-sprayed implants. Within the limits of this short-term experimental study, the results indicated that micro-rough titanium surfaces obtained with acid-etching procedures achieved a 33% greater bone-to-implant contact over machined titanium surfaces with an abutment-type roughness and provided enhanced mechanical interlocking.

Animals↗
PubMed2002

Muscle activation and torque development during maximal unilateral and bilateral isokinetic knee extensions.

BACKGROUND: The aim of this study was to investigate whether or not a bilateral strength deficit occurs during bilateral (BL) velocity controlled dynamic knee extensions and if the neural control of the knee extensors and flexors is altered during homologous muscle BL efforts. METHODS: Twenty-eight healthy and habitually active subjects, 13 female and 15 male, performed maximal unilateral (UL) and BL isokinetic leg extensions at a velocity of 60 degrees.s-1 through a 90 degrees range of motion of the knee joint (90 to 180 degrees). Knee extension torque and electromyographic activity (EMG) of the quadriceps and hamstrings muscles were recorded. RESULTS: The mean knee extensor torque produced in the BL condition (168 +/- 52 Nm) was 17% less than the sum of the two UL conditions (Sigma=202 +/- 56 Nm). During BL conditions, quadriceps EMG activity was less in both legs (left, 8.2 +/- 7.4% less and right, 13.9 +/- 9.1% less, respectively). There were no significant differences between BL and UL efforts for either left or right hamstrings activity. Eighteen subjects, who when asked to perform a maximal knee extension simultaneously activated their contralateral hamstrings, had significantly higher bilateral deficits (21%) compared to those who exhibited little or no contralateral hamstrings EMG activity (14%). CONCLUSIONS: The main findings of the study were that a bilateral strength deficit occurred when simultaneously maximally activating the homologous knee extensor muscles. This deficit was in all likelihood due to a less than maximal efferent drive to the quadriceps muscles. Hamstrings EMG activity was not greater during the BL knee extensions, which supports the notion that antagonistic muscle activity was not primarily responsible for the observed bilateral deficit.

Adult↗
PubMed2002

Passive resistive torque of the plantar flexors following eccentric loading as assessed by isokinetic dynamometry.

Isokinetic dynamometers may provide a useful means of measuring muscle stiffness resulting from eccentric exercise because they can measure torque from computer-controlled passive movements of joints (passive resistive torque; PRT). In this study, a Biodex measured increased ankle PRT (52%; p <.001) following heel drop exercise in nine young women. Therefore, isokinetic dynamometers can provide a means to study group changes as a result of eccentric exercise. Future studies are required to determine the reliability of this protocol before it can be advocated in studying single cases.

Adult↗
PubMed2003

Buccal and coronal bone augmentation using forced eruption and buccal root torque: a case report.

The following case report describes the buccal and coronal bone augmentation around an irretrievable tooth using forced eruption and buccal root torque for immediate nonsubmerged implant placement. A mandibular left second premolar with degree 2 mobility, severe buccal bone resorption, and interproximal angular bony defects was subjected to forced eruption and buccal root torque. Five months after this process, the tooth was displaced 15 mm coronally and the root apex faced buccally. Buccal and coronal bone augmentation and soft tissue enlargement were evident at reentry surgery. This technique enabled proper implant placement in a situation where the bone was compromised.

Alveolar Ridge Augmentation↗
PubMed2003

Force-torque input enhances medical VR applications.

Force-torque measuring input devices can significantly enhance the performance of classical simulation environments that are, for example, based on pure passive phantoms. Such devices allow not only the determination of force/torque amplitude and direction but also the contact point, where a torque-free force is applied to the phantom. The force/torque information can be displayed visually or acoustically, drive a realistic graphical animation environment or it can be saved and compared with a haptic library comprising the force/torque history of any medical specialist.

Computer Simulation↗
PubMed2004

The effects of rest interval length and training on quadriceps femoris muscle. Part I: knee extensor torque and muscle fatigue.

AIM: The purpose of this study was to examine the effects of rest interval on quadriceps femoris (QF) muscle strength and fatigue during short-term, high-intensity training. METHODS: Fifteen healthy males were assessed for isokinetic QF strength, via peak torque (PT), work (WK) and power (PW), at a pre-set angular velocity of 180 deg x s(-1). Quadriceps femoris muscle fatigue was evaluated as the decline in isokinetic work and power (slope) across 30 maximal concentric contractions. Subjects were randomly assigned to 1 of 3 groups: Group 1 (short rest interval), Group 2 (long rest interval), and Group 3 (control-no training). Subjects in Group 1 received a rest period of 40 s in between exercise sets corresponding to a 2:1 rest:work ratio. Subjects in Group 2 received a rest period of 160 s corresponding to an 8:1 rest:work ratio. Groups 1 and 2 performed isokinetic knee extension contractions at 180 deg x s(-1) 2 days per week for 6 weeks. RESULTS: The results demonstrated a significant increase in QF muscle PT across the 6 week training period in the long rest interval group, and no significant changes in the short rest interval and control groups. Quadriceps femoris muscle work and power were observed to not change significantly across the training period in all 3 groups. The reduction in QF muscle work across the single set of 30 repetitions was observed to decrease significantly in the control group across the 6 week duration; no other significant changes in QF muscle fatigue for work and power were observed. CONCLUSION: The major findings of this study suggests that the possibility of different physiological mechanisms of adaptation exist for QF muscle peak torque, work and power, while changes in muscle fatigue resistance may be present when assessed across multiple, rather than a single, bouts of activity.

Adaptation, Physiological↗
PubMed2005

Comparison of Fourier and wavelet transform procedures for examining mechanomyographic and electromyographic frequency versus isokinetic torque relationships.

The purpose of this study was to compare the isokinetic torque-related patterns for mechanomyographic (MMG) and electromyographic (EMG) center frequency [wavelet center frequency (CF), mean power frequency (MPF), and median frequency (MDF)] determined by the fast Fourier transform (FFT) and discrete wavelet transform (DWT). Ten adults [mean +/- SD age = 22.0 +/- 3.4 yrs] performed submaximal to maximal, isokinetic muscle actions of the biceps brachii on a Cybex II dynamometer. For both MMG and EMG, the CF, MPF, and MDF values were intercorrelated at (r = 0.91-0.98). Quadratic models provided the best fit for the absolute and normalized CF, MPF, and MDF versus isokinetic torque relationships for MMG (R2 = 0.67-0.83) and EMG (R2 = 0.72-0.90). The similarities among the CF, MPF, and MDF patterns suggested that Fourier or wavelet transform procedures can be used to examine the patterns of MMG and EMG responses during dynamic muscle actions.

Adult↗
PubMed2005

Contractile torque as a steering mechanism for orientation of adherent cells.

It is well established that adherent cells change their orientation in response to non-uniform substrate stretching. Most observations indicate that cells orient away from the direction of the maximal substrate strain, whereas in some cases cells also align with the direction of the maximal strain. Previous studies suggest that orientation and steering of the cell may be closely tied to cytoskeletal contractile stress but they could not explain the mechanisms that direct cell reorientation. This led us to develop a simple, mechanistic theoretical model that could predict a direction of cell orientation in response to mechanical nonuniformities of the substrate. The model leads to a simple physical mechanism--namely the contractile torque--that directs the cell toward a new orientation in response to anisotropic substrate stretching or substrate material anisotropy. A direction of the torque is determined by a dependence of the contractile stress on substrate strain. Model predictions are tested in the case of simple elongation of the substrate and found to be consistent with experimental data from the literature.

Cell Adhesion↗
PubMed2006

[The compensation of post-treatment incisor torque in sagittal jaw relationship].

OBJECTIVE: To investigate the dental compensation in different sagittal jaw relationships. METHODS: One hundred and fifty-seven post-treatment cases with satisfied outcome were chosen. Computerized cephalometric analysis was performed to evaluate the sagittal jaw relationship. Incisor torque were measured based on study models. Correlation analysis was performed. RESULTS: Compared with skeletal class I cases, the upper incisors of skeletal class III cases were more proclined, and lower incisors were more retroclined; the opposite result was found in skeletal class II cases. Dental compensation in class I cases took place primarily at lower incisors. CONCLUSIONS: Incisor torque control was important in patients with various sagittal jaw relationships.

Cephalometry↗
PubMedDate not supplied

Removal torque values of titanium implants in the maxilla of miniature pigs.

The purpose of this study was to compare side-by-side two different titanium screw-type implants in the maxillae of miniature pigs. The test implants had a machined and acid-etched surface (Osseotite) whereas the control implants were sandblasted and acid-etched (SLA). After 4, 8, and 12 weeks of healing, removal torque testing was performed to evaluate the shear strength of the bone-implant interface for both implant types. The results demonstrated significant differences between both implant types (P < .01). Osseotite implants revealed mean removal torque values (RTV) of 62.5 Ncm at 4 weeks, 87.6 Ncm at 8 weeks, and 95.7 Ncm at 12 weeks of healing. In contrast, the SLA implants demonstrated mean RTV of 109.6 Ncm, 196.7 Ncm, and 186.8 Ncm at corresponding healing periods. The mean RTV for SLA implants was 75% to 125% higher than for Osseotite implants up to 3 months of healing.

Analysis of Variance↗
PubMed2000

External forces and torques generated by the brachiating white-handed gibbon (Hylobates lar).

We compared the kinetics of brachiation to bipedal walking and running. Gibbons use pectoral limbs in continuous contact with their overhead support at slow speeds, but exhibit aerial phases (or ricochetal brachiation) at faster speeds. This basic interaction between limb and support suggests some analogy to walking and running. We quantified the forces in three axes and torque about the vertical axis generated by a brachiating White-handed gibbon (Hylobates lar) and compared them with bipedal locomotion. Handholds oriented perpendicular to the direction of travel (as in ladder rungs) were spaced 0.80, 1.20, 1.60, 1.72, 1.95, and 2.25 m apart. The gibbon proportionally matched forward velocity to stride length. Handhold reaction forces resembled ground reaction forces of running humans except that the order of horizontal braking and propulsion were reversed. Peak vertical forces in brachiation increased with speed as in bipedal locomotion. In contrast to bipedalism, however, peak horizontal forces changed little with speed. Gait transition occurred within the same relative velocity range as the walk-run transition in bipeds (Froude number = 0.3-0.6). We oriented handholds parallel to the direction of travel (as in a continuous pole) at 0.80 and 1.60 m spacings. In ricochetal brachiation, the gibbon generated greater torque with handholds oriented perpendicular as opposed to parallel to the direction of travel. Handhold orientation did not affect peak forces. The similarities and differences between brachiation and bipedalism offer insight into the ubiquity of mechanical principles guiding all limbed locomotion and the distinctiveness of brachiation as a unique mode of locomotion.

Animals↗
PubMed1989

A testing technique allowing cyclic application of axial, bending, and torque loads to fracture plates to examine screw loosening.

Orthopaedic internal fracture fixation plates are subjected to combined axial, bending, and torsional loads in vivo which can cause screw loosening and implant failure. This paper outlines a relatively simple technique which allows controlled application of combined axial, bending, and torsional loading to examine the loosening rate of cortical screws used to attach these plates. Fiber reinforced polycarbonate rods with a tensile strength similar to that of cortical bone were cut at half their length to simulate fractured tibii. These were compression plated using a standardized technique and placed in a loading fixture. Joint loads at the knee determined from force plate analysis and statics were applied to a plated fixture during testing. The design of the fixture allowed adjustment of the proportion of bending and torsional loads applied to the test samples. It also allowed a reproducible means of applying a predetermined axial, bending, and torsional load. Screw loosening following cyclical loading was evaluated by measuring the amount of angular displacement required to retighten screws to a prescribed torque value. A torque wrench was modified to allow the measurement of these displacements.

Bone Plates↗
PubMed1994

Torque free asymmetric gradient coils for echo planar imaging.

In this work, we present a new torque-free asymmetric gradient coil that is capable of generating high quality axial, sagittal, and coronal echo planar images of the human head. This gradient set was calculated using the Biot-Savart law and least square approaches to optimize the field in the region of interest and to minimize net torques. The resulting structure has excellent shoulder-to-coil clearance and, as such, has the advantage of providing good patient access to the linear portion of the gradient while minimizing patient discomfort from claustrophobia.

Echo-Planar Imaging↗