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PubMed1988

Peak torque and OBLA running capacity in male orienteers.

The isokinetic (30, 60, 120 and 180 degrees s-1) peak torque of m. quadriceps femoris and m. triceps surae, and the running velocity at the onset of blood lactate accumulation (VOBLA) were determined at three different occasions (November, April and September) during a year in 15 male élite orienteers. The amount and type of training for each individual was also registered. At the first test (November) there was no significant intra-individual correlation between peak torque of m. quadriceps and m. triceps surae. A negative correlation was found between VOBLA and peak torque of m. quadriceps at the lower velocities of angular motion, but not at the higher. The peak torque of m. triceps surae increased during the training period and decreased during the competition period back to the original level. Over the whole year the peak torque of m. quadriceps increased while no changes could be demonstrated within the two periods of the study. The running velocity at the onset of blood lactate accumulation increased during both training and competition periods. The changes in VOBLA were negatively associated with the changes in peak torque of m. quadriceps at 180 degrees s-1 during the training period. During the competition period the changes in VOBLA were, for the majority of the orienteers, negatively correlated to the ratio of quality:quantity running, i.e. to a high content of forest running.

Adult↗
PubMed1995

Electrically evoked torque-velocity characteristics and isomyosin composition of the triceps surae in young and elderly men.

The electrically evoked isokinetic torque-velocity relationship of the triceps surae of eight elderly and four non-trained young men was examined in relation to the isomyosin composition of the soleus and the gastrocnemius muscles, determined under non-denaturing conditions using pyrophosphate gel electrophoresis. The angle specific torque-velocity properties of the triceps surae were measured using maximal percutaneous electrical stimulation at 50 Hz and a release technique. The elderly subjects generated significantly (P < 0.05) less absolute torque at all angular velocities when compared with the young subjects. When the isokinetic data were normalized to the isometric torque, the lower normalized torques generated by the elderly subjects were not statistically different from the young. The total fast isomyosin (FM) content of the soleus and gastrocnemius in the elderly subjects was 22 +/- 13 and 35+/- 18%, respectively. This compared with 29 +/- 8 (n.s) and 44 +/- 8% (n.s.) in the young subjects. When the gastrocnemius and soleus muscles were given an equal weighting and considered together to represent the whole triceps surae, the normalized torque at the fixed angular velocity of 5 rads s-1 was significantly associated with %FM (r = 0.90, P < 0.01), and the isomyosin bands %FM1 (r = 0.90, P < 0.01) and %FM2 (r = 0.93, P < 0.001) when only the elderly subjects were considered. No relationships were observed between contractile characteristics and contractile protein profile when only the young subjects were considered. This was despite the inclusion of a further two sprint and three endurance trained athletes to increase the range of contractile characteristics and differences in muscle composition.

Adult↗
PubMed1994

Dynamic measurement of the torque-speed characteristics of dental high speed air turbine handpieces.

The first requirement for adequate performance of an air turbine handpiece is sufficient power. Suppliers of such handpieces do not provide data on the power produced by their equipment. A method for determining the torque, speed and hence power during simulated operation is described. Forty-one new and used handpieces were tested. Maximum speeds up to 500,000 rpm, maximum torques up to 2.33 N.mm and maximum power up to 29.6 watt were observed. The maximum power was produced at between 49 and 79 per cent of the free-running speed. A relationship between maximum power and stall torque was noted. The maximum torque is at stall for ball-bearing units. The stall torque can be easily determined by a simple stall torque test which is described. Using this test, the performance of handpieces can be easily checked in the clinic. The one air-bearing handpiece tested performed in a manner similar to the others, except that stall occurred below 60,000 rpm.

Dental High-Speed Equipment↗
PubMed1996

Torque generation in the flagellar motor of Escherichia coli: evidence of a direct role for FliG but not for FliM or FliN.

Among the many proteins needed for assembly and function of bacterial flagella, FliG, FliM, and FliN have attracted special attention because mutant phenotypes suggest that they are needed not only for flagellar assembly but also for torque generation and for controlling the direction of motor rotation. A role for these proteins in torque generation is suggested by the existence of mutations in each of them that produce the Mot- (or paralyzed) phenotype, in which flagella are assembled and appear normal but do not rotate. The presumption is that Mot- defects cause paralysis by specifically disrupting functions essential for torque generation, while preserving the features of a protein needed for flagellar assembly. Here, we present evidence that the reported mot mutations in fliM and fliN do not disrupt torque-generating functions specifically but, instead, affect the incorporation of proteins into the flagellum. The fliM and fliN mutants are immotile at normal expression levels but become motile when the mutant proteins and/or other, evidently interacting flagellar proteins are overexpressed. In contrast, many of the reported fliG mot mutations abolish motility at all expression levels, while permitting flagellar assembly, and thus appear to disrupt torque generation specifically. These mutations are clustered in a segment of about 100 residues at the carboxyl terminus of FliG. A slightly larger carboxyl-terminal segment of 126 residues accumulates in the cells when expressed alone and thus probably constitutes a stable, independently folded domain. We suggest that the carboxyl-terminal domain of FliG functions specifically in torque generation, forming the rotor portion of the site of energy transduction in the flagellar motor.

Bacterial Proteins↗
PubMed1979

Torque-velocity relationships and muscle fiber composition in elite female athletes.

The relationship between the predominance of fast and slow muscle fibers of the vastus lateralis and "in vivo" torque velocity properties in 22 female athletes was studied. Fiber types were classified according to the histochemical myofibrillar adenosine triphosphatase technique at a basic pH. Maximal extensor troques were recorded at 30 degrees from full extension at four selected velocities. While results confirm earlier reports on muscle fiber type and performance, an additional finding was that as knee extension velocities increased from 0 to 95 degrees/s angle specific extensor torque production did not decline as seen in in vitro muscle preparations. The difference in extensor torque between 0 and 96 degrees/s appeared far more critical than the differences observed between 96 and 288 degrees/s. Significant differences in torque were seen at 96, 192, and 288 degrees/s in thos with greater than 50% and less than 50% slow-twitch fibers. When expressed per kilogram of body weight the subjects with greater than 50% fast-twitch fiber produced the greatest torque at 192 degrees/s. These results suggest that the velocity at which torque begins to decline in vivo is related to the proportion of slow-twitch fibers in the vastus lateralismuscle.

Adolescent↗
PubMed1985

Torque-velocity relationship in isokinetic cycling exercise.

Seven healthy female subjects performed brief (less than 10 s) periods of maximal exercise on a constant-velocity cycle ergometer, over the functional range of pedaling velocities, and an isometric contraction with each leg. There was an inverse relationship between peak torque and pedal crank velocity in all subjects; isometric torque was (mean +/- SE) 19.8 +/- 8.3% greater than the torque recorded at the slowest velocity of 11 rpm. The torque-velocity relationship was described best by a single exponential equation: y = 189.6 X e-0.0834x, where y is peak torque in Newton . meters and x is crank velocity in revolutions per minute. Peak power was a parabolic function of crank velocity; the data were fitted suitably by a second-order polynomial equation: y = -0.0589x2 + 14.504x + 47.092, where y is peak power in watts and x is crank velocity in revolutions per minute. Maximal peak power occurred at crank velocities ranging from 120 to 160 rpm, when the torque was 0.36 +/- 0.06 of the maximal isometric tension. These results demonstrate the importance of recording velocity in measurements of dynamic maximal power.

Adult↗
PubMed2006

Nonuniform distribution of reach-related and torque-related activity in upper arm muscles and neurons of primary motor cortex.

The present study examined the activity of primate shoulder and elbow muscles using a novel reaching task. We enforced similar patterns of center-out movement while the animals countered viscous loads at their shoulder, elbow, both joints, or neither joint. Accordingly, we could examine reach-related activity during the unloaded condition and torque-related activity by comparing activity across load conditions. During unloaded reaching the upper arm muscles exhibited a bimodal distribution of preferred hand direction. Maximal reach-related activity occurred with hand movements mostly toward or away from the body. Arm muscles also exhibited a bimodal distribution of their preferred torque direction. Maximal torque-related activity typically occurred with shoulder-extension/elbow-flexion torque or shoulder-flexion/elbow-extension torque. Similar biases in reach-related and torque-related activity could be reproduced by optimizing a global measure of muscle activity. These biases were also observed in the neural activity of primary motor cortex (M1). The parallels between M1 and muscular activity demonstrate another link between motor cortical processing and the motor periphery and may reflect an optimization process performed by the sensorimotor system.

Algorithms↗
PubMed1996

Coordinating two degrees of freedom during human arm movement: load and speed invariance of relative joint torques.

1. Eight subjects performed three series of pointing tasks with the unconstrained arm. Series one and two required subjects to move between two fixed targets as quickly as possible with different weights attached to the wrist. By specifying initial and final positions of the finger tip, the first series was performed by flexion of both shoulder and elbow and the second by shoulder flexion and elbow extension. The third series required flexion at both joints, and subjects were instructed to vary movement speed. We examined how variations in load or intended speed were associated with changes in the amount and timing of the electromyographic (EMG) activity and the net muscle torque production. 2. EMG and torque patterns at the individual joints varied with load and speed according to most of the same rules we have described for single-joint movements. 1) Movements were produced by biphasic torque pulses and biphasic or triphasic EMG bursts at both joints. 2) The accelerating impulse was proportional to the load when the subject moved "as fast and accurately as possible" or to speed if that was intentionally varied. 3) The area of the EMG bursts of agonist muscles varied with the impulse. 4) The rates of rise of the net muscle torques and of the EMG bursts were proportional to intended speed and insensitive to inertial load. 5) The areas of the antagonist muscle EMG bursts were proportional to intended movement speed but showed less dependence on load, which is unlike what is observed during single-joint movements. 3. Comparisons across joints showed that the impulse produced at the shoulder was proportional to that produced at the elbow as both varied together with load and speed. The torques at the two joints varied in close synchrony, achieving maxima and going through zero almost simultaneously. 4. We hypothesize that "coordination" of the elbow and shoulder is by the planning and generation of synchronized, biphasic muscle torque pulses that remain in near linear proportionality to each other throughout most of the movement. This linear synergy produces movements with the commonly observed kinematic properties and that are preserved over changes in speed and load.

Arm↗
PubMedDate not supplied

Torque production in the shoulder of the normal young adult male. The interaction of function, dominance, joint angle, and angular velocity.

Shoulder torque measurements were obtained from 36 normal young adult males during flexion, abduction, internal rotation, and external rotation. Normative, angle-specific torque measurements were determined under isometric conditions and isokinetically at 48 deg/sec. The effects of dominance, angular velocity, and joint position were determined and a method provided for determining the expected maximal torque at a specific speed and position based upon torque measurements from the contralateral shoulder. This method can be used in cases of unilateral shoulder abnormalities to predict normative torque values for the affected side based on torque measurements from the unaffected shoulder.

Adult↗
PubMed1999

The relationship between leg stepping pattern and yaw torque oscillations in curve walking of two crayfish species

Curve walking in two species of crayfish, Procambarus clarkii and Astacus leptodactylus, was investigated to test whether the mechanism underlying curve walking is the synchronous action of a centrally pre-programmed leg tripod or whether it is the action of one principal leg that produces the main body yaw torque. Curve walking was induced by an optomotor visual stimulus, and the yaw torque produced by the tethered animals was measured in open-loop conditions. Our main results suggest that the yaw torque oscillations in both P. clarkii and A. leptodactylus are related to the movement of outer leg 4 (i.e. leg 4 on the outside of the turn). That is, the peaks in the yaw torque occur, on average, in synchrony with the power stroke of outer leg 4. When comparing the results of this open-loop experiment on P. clarkii with results previously obtained for curve walking in untethered individuals of the same species, we found a much higher variability in leg coordination in the open-loop situation. Similarly, here we did not find the same level of synchrony in the tripod (formed by outer leg 4 and inner legs 2 and 5) observed during untethered free walking. Therefore, we suggest that tethered conditions may diminish the need for stability and thus allow outer leg 4 to produce a body rotation regardless of the leg stepping configuration. The characteristics of leg 4 are in line with its major role in turning. According to previous studies, legs 4 provide the largest force and the largest step amplitude during walking, and their force includes both a pulling and a pushing component which can facilitate the control of turning. Although it is apparent that outer leg 4 is not the only leg that can produce an inward yaw torque, its major role in modulating the yaw torque suggests that there may be a specific, centrally generated control of outer leg 4 during curve walking in crayfish.

Journal Article↗
PubMed1994

Effect of hip position on gravity effect torque.

Hip position has been hypothesized to influence gravity effect torque (GET) at the knee during isokinetic testing; however, no data exist to support or refute this hypothesis. Therefore, the purposes of this study were 1) to determine if a significant difference exists between GET in seated and supine positions, 2) to determine the effect of the supine and seated GET on isokinetic peak torque values, and 3) to determine the relationship between hamstring flexibility and GET. Gravity effect torque was recorded in supine and seated positions. Peak torque values in flexion and extension were obtained on a isokinetic dynamometer at 1.047 and 5.235 rads.s-1 (60 and 300 degrees.s-1, respectively). Hamstring flexibility was assessed by the active knee extension test (AKET). The mean seated GET value was 5.64 Nm higher than the mean supine GET value (F(1,82) = 97.85, P = 0.0001). Significant correlations existed between hamstring flexibility and GET values measured in the seated and supine positions (r = 0.45, P = 0.0001, and r = 0.30, P = 0.0058, respectively). Significant differences in peak torque values occurred for three of the four isokinetic conditions when using different GET values (P-value 0.0002-0.0049). Although mean differences in peak torque values were only 2.43-4.23 Nm, these differences may translate to significant errors in the isokinetic measurement of the injured population undergoing rehabilitation. Furthermore, every attempt should be made to improve the validity of isokinetic testing. Therefore, we recommend the supine position for GET determination.

Adult↗
PubMed1996

A biomechanical study of torque and accuracy of halo pin insertional devices.

The purpose of the present study was to assess the accuracy and repeatability of the torque achieved with a variety of devices used for the insertion of halo pins. We found that equivalent devices from the same manufacturer did not reliably achieve the same torque, that the same device used by different surgeons did not reliably achieve the same torque, and that the devices achieved varying levels of accuracy and repeatability. The proportion of trials in which the achieved torque was within +/- 10 per cent of the intended torque averaged 64 per cent (range, less than 1 to 100 per cent). Our data suggest that the insertion of halo pins with use of most currently available torque-setting devices is an inherently inaccurate process.

Biomechanical Phenomena↗
PubMed1988

Torque and cerebral lateralization: a questionable link.

Past research has suggested that torque (the tendency to draw circles in a clockwise direction) may be indicative of less cerebral lateralization. This notion is based on the finding that left-handers demonstrate a greater incidence of torque than right-handers. The present study attempted to investigate this relationship using both conjugate lateral eye movements (CLEM) and handedness as indices of cerebral lateralization. Subjects were 40 male and 40 female right-handed and 16 male and 16 female nonright-handed university students. Consistent with past studies, torque was significantly related to handedness, with nonright-handers demonstrating a greater incidence of torque. However, no relationship between torque and CLEM was found. On the basis of these findings, it is argued that the observed relationship between torque and handedness may be due more to muscle mechanics of the hands rather than any relationship with cerebral lateralization.

Adult↗
PubMed1992

[Isokinetic torque of the knee extensor and flexor in patients with recurrent patellar dislocation].

UNLABELLED: In order to establish the role of muscle strength in the recurrent dislocation of the patella, an isokinetic study was performed using BIODEX, by which the concentric (CC) and passive eccentric (PEC) torques of the quadriceps and hamstrings were measured. The angle velocity was set at 30 degrees and 90 degrees/sec. The subjects were divided into three groups: (I) non-surgical, (II) surgical and (III) normal control. In each group 20 knees were tested, and the following results were obtained. 1. Peak torque: At either 30 degrees/sec or 90 degrees/sec of velocity, it was significantly smaller in group I. On the other hand, the torque in group II was similar to that of group III. 2. E/C (eccentric torque/concentric torque) ratio: PEC was divided by CC to express a muscular strength balance. At 30 degrees/sec velocity, group I showed a significantly high E/C ratio. CONCLUSION: The knees with recurrent dislocation of the patella exhibited significantly lower peak torque and irregular curve patterns. The muscle strength, has been restored to a near-normal level in the surgical group, therefore, the muscle weakness in this disorder can be considered to be a secondary factor. The eccentric torque appeared to play a major role in the development of recurrent dislocation of the patella.

Biomechanical Phenomena↗
PubMed1991

Effect of activation force on knee extensor torques.

The purpose of this study was to determine whether the magnitude of the activation force, defined as the force that must be applied to the load cell in order to activate the resistance arm of an isokinetic dynamometer, affected knee extensor torques. Twenty-four healthy female subjects performed resisted knee extension through the range of 95 degrees to 5 degrees knee flexion, with a 5-s rest between concentric and eccentric muscle actions. Six exercise sets, composed of the combinations of activation force (20,50, and 100 N) and angular velocity (45 and 135 degrees.s-1), were randomly assigned on each of two occasions, completed within a 10-d period. Although peak torques were not affected by the activation force, average torques, eccentric torques at mid-range (50 degrees knee flexion), and torques during the initial portion of each muscle action (80 degrees knee flexion during concentric muscle actions and 20 degrees flexion during eccentric actions) increased as the activation force increased. The effect of the activation force tended to be more pronounced during eccentric than during concentric muscle actions, and at the faster angular velocity. Comparisons of torques should be based on similar test protocols, including activation force.

Adult↗
PubMed1983

A force-torque analysis of the kip on the horizontal bar.

The purpose of this study was to determine the forces and torques on the horizontal bar during the kip. Six Canadian male gymnasts were filmed using a high speed camera during a short gymnastic routine including a kip on a horizontal bar which was wired with strain and torque gauges. During the performance, voltage outputs representing force and torque were amplified and recorded on tape. The force-torque data were then subjected to computer analysis. Maximum forces and torques were determined and force-angle plots were normalized by dividing force by body weight. The range of maximum forces was 1344-1563 N with a mean of 1444 N, which was approximately 2.3 times the body weight. The maximum forces were obtained when the center of mass was almost directly below the bar with the timing of maximum force application ranging +/- 0.1 sec from either side of 180 degrees. Maximum torques ranged from 10.0-21.0 N X m (Mean 17.3 N X m).

Adult↗
PubMed1983

The effect of varied hip angles on the generation of internal tibial rotary torque.

Previous researchers have determined that 90 degrees of knee flexion is an appropriate angle to condition the internal tibial rotators. Because the majority of internal tibial rotators are two-joint muscles crossing both the knee and the hip, the influence of the hip angle on the generation of rotary torque was examined. The purpose of this study was to investigate the effect of four hip angles on the generation of internal tibial rotational torque with the knee positioned at 90 degrees of flexion. Forty subjects, 20 males and 20 females, were tested at four positions of hip flexion (120 degrees, 90 degrees, 45 degrees, 10 degrees) using a modified Cybex II isokinetic dynamometer, and their maximal mean internal rotary torque values were recorded. The subjects were placed in a custom-made orthotic-type boot to minimize the motions of the talo-calcaneal joint. Sixty percent of the males and 65% of the females generated their greatest absolute torque value at 120 degrees of hip flexion. A procedure investigating the rankings of the maximal mean torque values at each of the tested hip positions revealed a significant difference between the hip positions of 120 and 10 degrees for both populations (P less than 0.001), and the male population also demonstrated significance between the angles of 120 and 45 degrees and 90 and 10 degrees (P less than 0.05). The practical significance of this study offers some additional information regarding the appropriate positioning for rehabilitation of the internal tibial rotators. The data suggests that if maximal torque generation is desired, the internal tibial rotators should be tested and exercised with the hip flexed to 120 degrees to take advantage of the length-tension relationship and the biomechanical principles of the rotary muscles.

Adolescent↗
PubMed1982

The nature of torque "overshoot" in Cybex isokinetic dynamometry.

Transient peaks or "spikes" frequently appear in the initial segments of torque curves recorded with the Cybex isokinetic dynamometer. The purpose of this investigation was to determine whether these spikes represent artifact or transient initial surges of true muscular force output. Cinematographic analysis using both inert weights and a human subject as the source of torque input to the Cybex revealed that the dynamometer's input lever initially exceeded the pre-set angular velocity by an amount ranging from 11% (inert weight; pre-set Cybex velocity = 180 degrees/s) to 200% (human hip abduction; pre-set velocity = 30 degrees/s). The majority of this "overspeeding" occurred in the latter part of the free acceleration period, prior to the engagement of the dynamometer's resistance mechanism. The remainder occurred in the initial part of the elastic loading phase, just after resistance had engaged. A sharp deceleration of the overspeeding lever and the affixed weight or limb then followed in response to the dynamometer's continuing build-up of resistance. Simultaneous with this deceleration, a prominent torque spike was recorded that superseded the correct (mechanical equilibrium) torque value. Within our error of measurement, the deceleration observed in the film quantitatively accounted for all of the "overshoot" torque, i.e., that amount of the spike that exceeded the correct value. It was concluded that such prominent, initial torque spikes represent inertial forces and should not be confused with true muscular tension development.

Biomechanical Phenomena↗