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PubMed2002

Utilization and compensation of interaction torques during ball-throwing movements.

The manner in which the CNS deals with interaction torques at each joint in ball throwing was investigated by instructing subjects to throw a ball at three different speeds, using two (elbow and wrist) or three joints (shoulder, elbow, and wrist). The results indicated that the role of the muscle torque at the most proximal joint was to accelerate the most proximal joint and to produce the effect of interjoint interaction on the distal joints. In the three-joint throwing, shoulder muscle torque produced the assistive interaction torque for the elbow, which was effectively utilized to generate large elbow angular velocity when throwing fast. However, at the wrist, the muscle torque always counteracted the interaction torque. By this kinetic mechanism, the wrist angular velocity at the ball-release time was kept relatively constant irrespective of ball speed, which would lead to an accurate ball release. Thus it was concluded that humans can adjust the speed and accuracy of ball-throwing by utilizing interaction torque or compensating for it.

Adult↗
PubMed2004

Humeral torque in professional baseball pitchers.

BACKGROUND: Spontaneous fracture of the humeral shaft in throwers is a rare but well-known phenomenon. Although it has been hypothesized that the biomechanics of the throw cause such fractures, it is not clear how or when the fractures occur in the pitching motion. METHODS: The torque acting about the long axis of the humerus was calculated in 25 professional baseball pitchers throwing in game situations. RESULTS: Peak humeral axial torque reached a mean value of 92 +/- 16 Nm near the time of maximum shoulder external rotation at the end of the cocking phase. This torque tended to externally rotate the distal end of the humerus relative to its proximal end. The direction of the torque was consistent with the external rotation spiral fractures of the humerus noted to occur in throwers. The magnitude of the peak humeral torque averaged 48% of the theoretical torsional strength of the humerus, suggesting that repetitive stress plays a role in humeral shaft fractures. CONCLUSIONS: Fractures are most likely to occur near the time of maximum shoulder external rotation when humeral torque peaks. Pitchers whose elbows were more extended at stride foot contact tended to have lower peak humeral torques.

Adult↗
PubMedDate not supplied

Effects of Theraband and lightweight dumbbell training on shoulder rotation torque and serve performance in college tennis players.

The purpose of this study was to determine whether a 4-week isotonic resistance training program using Theraband elastic tubing and lightweight dumbbells would significantly increase concentric shoulder rotator strength or velocity of serve or both in a group of elite-level tennis players. Twenty-two male and female varsity college tennis players were randomly assigned to control or 4-week training groups. Subjects were pre- and posttested in concentric internal and external rotation torque using an isokinetic dynamometer. Functional performance was assessed before and after training by recording the peak and average velocities of eight maximal serves. The experimental group exhibited significant gains in internal rotation torque at both slow (120 deg/sec) and fast speeds (300 deg/sec) for total work and in peak torque to body weight ratio and torque acceleration energy at the fast speed. This group also exhibited significant gains in external rotation torque for the same parameters at fast speed. Regarding speed to serve, the experimental group exhibited significantly greater increase in peak speed (+6.0% compared with -1.8%) and average speed (+7.9% compared with -2.3%) compared with the control group. Men exhibited greater internal and external rotation torque on all parameters and in peak and mean speed of serve on both evaluations. Men also exhibited greater imbalance in external to internal rotation torque ratios. In conclusion, resistance training using Theraband tubing and lightweight dumbbells may have beneficial effects on strength and functional performance in college-level tennis players.

Acceleration↗
PubMed2003

Reliability of isokinetic dynamometry in assessing plantarflexion torque following Achilles tendon rupture.

BACKGROUND: Research investigating the most effective management of Achilles tendon injury has been limited by a lack of reliable outcome measurements. Calf strength may be a valid outcome measure, not only in terms of identifying possible risk factors for reoccurrence of rupture, but also as an indicator of recovery. Isokinetic dynamometry has been suggested as an effective tool for measuring the torque of the calf muscles. Such measurements have demonstrated high reliability for the assessment of calf muscle torque in healthy subjects. However, there are no published data to demonstrate the reliability of isokinetic dynamometry in subjects with pathology in the Achilles tendon. The purpose of this study was to assess the inter- and intraobserver reliability of isokinetic dynamometry for assessing plantarflexion torque following Achilles tendon rupture. METHODS: Two independent observers used the Kin-com Dynamometer to measure the torque of the plantarflexors in 22 subjects 6 months after unilateral rupture of the Achilles tendon. Twelve subjects had been managed operatively and 10 nonoperatively. Subjects were placed in the prone position with the knee extended. Measurements of peak torque, average torque, and total work were made for both concentric and eccentric plantarflexion movements at 60 degrees per second. RESULTS: Intraclass correlation coefficients were used to calculate reliability of measurements both within and between observers. Reliability was slightly greater on the healthy side (0.74-0.92 ICC) in comparison with the injured side (0.74-0.89 ICC). CONCLUSION: The results of this study suggest that isokinetic dynamometry provides a reliable method of measuring the torque of the plantarflexors following rupture of the Achilles tendon, with levels of reliability comparable with those from healthy subjects. The study concludes that this would be a valuable and reliable outcome measure for use in clinical trials.

Achilles Tendon↗
PubMed2003

The effects of antagonist prefatigue on agonist torque and electromyography.

This study assessed the effects of hamstring prefatigue on peak torque, peak power, time to peak torque, knee angle of peak torque, and electromyography (EMG) activity of the hamstrings and quadriceps group during knee extensions at angular velocities of 60 degrees, 180 degrees, and 300 degrees.s(-1). Twenty Division I wrestlers performed 5 maximal knee extensions in prefatigued and nonfatigued conditions of the hamstring group. This study demonstrated that when the hamstrings were prefatigued, the quadriceps produced significant decreases in peak torque of 1.7% (p < 0.05), peak power of 11% (p < 0.05), and rate to peak torque of 6.4% (p < 0.01) as compared with the nonfatigued state. When the hamstrings were prefatigued, they produced a 25% greater amount of EMG activity during knee extension (p < 0.01) than when not prefatigued. There was no significant difference in quadriceps EMG activity whether the hamstring group was prefatigued or not (p > 0.05). The decrease in quadriceps peak torque during the prefatigued condition was more pronounced (p < 0.01) at an angular velocity of 60 degrees.s(-1) than at 180 degrees or 300 degrees.s(-1). In other words, prefatiguing the antagonist appears to be most detrimental to torque output of the quadriceps in the condition that most closely replicates the speed at which "isotonic" weight training occurs (60 degrees.s(-1)) and suggests a limitation to agonist-antagonist superset training.

Adult↗
PubMed2006

Biomechanical analysis of tibial torque and knee flexion angle: implications for understanding knee injury.

Knee injuries are common in sports activities. Understanding the mechanisms of injury allows for better treatment of these injuries and for the development of effective prevention programmes. Tibial torque and knee flexion angle have been associated with several mechanisms of injury in the knee. This article focuses on the injury to the anterior cruciate ligament (ACL), the posterior cruciate ligament (PCL) and the meniscus of the knee as they relate to knee flexion angle and tibial torque. Hyperflexion and hyperextension with the application of tibial torque have both been implicated in the mechanism of ACL injury. A combination of anterior tibial force and internal tibial torque near full extension puts the ACL at high risk for injury. Hyperflexion also increases ACL force; however, in this position, internal and external tibial torque only minimally increase ACL force. Several successful prevention programmes have been based on these biomechanical factors. Injury to the PCL typically occurs in a flexed or hyperflexed knee position. The effects of application of a tibial torque, both internally and externally, remains controversial. Biomechanical studies have shown an increase in PCL force with knee flexion and the application of internal tibial torque, while others have shown that PCL-deficient knees have greater external tibial rotation. The meniscus must endure greater compressive loads at higher flexion angles of the knee and, as a result, are more prone to injury in these positions. In addition, ACL deficiency puts the meniscus at greater risk for injury. Reducing the forces on the ACL, PCL and meniscus during athletic activity through training, the use of appropriate equipment and safe surfaces will help to reduce injury to these structures.

Anterior Cruciate Ligament Injuries↗
PubMed2002

The effect of prolonged static and cyclic stretching on ankle joint stiffness, torque relaxation, and gait in people with stroke.

BACKGROUND AND PURPOSE: Continuous passive motion (cyclic stretching applied to the subject's limb) has been used for the rehabilitation of some orthopedic impairments; however, few researchers have considered its application in the management of neurological disorders such as stroke. The purpose of this study was to examine the short-term effects of prolonged static and cyclic calf stretching on passive ankle joint stiffness, torque relaxation, and gait in people with ischemic stroke. SUBJECTS: Ten community-dwelling people (mean age=64.6 years, SD=8.76, range=53-76) who were diagnosed with a cerebrovascular accident volunteered to be subjects. METHODS: Participants engaged in one 30-minute static stretch and one 30-minute cyclic stretch of the calf muscle, using an isokinetic dynamometer that also collected torque and angle measurements. Before and after treatments, 10-m walking times were collected. Ankle joint stiffness was calculated from the slope of the torque and angle curves before and immediately after treatments, and torque relaxation was calculated as the percentage of decrease in peak passive torque over the 30-minute stretch durations. RESULTS: Ankle joint stiffness decreased by 35% and 30% after the static and cyclic stretches, respectively. Stiffness values and 10-m walk times were not different between conditions. The amount of torque relaxation was 53% greater for static stretching than for cyclic stretching. DISCUSSION AND CONCLUSION: These preliminary data from a very small sample of people with stroke indicate that ankle joint stiffness decreases after both prolonged static and cyclic stretches; however, neither technique appears to be better at reducing stiffness in people with stroke. Torque relaxation is greater after static stretching than after cyclic stretching, and walking speed does not appear to be influenced by the stretching treatments used in our study.

Aged↗
PubMedDate not supplied

Removal torque of immediately loaded transitional endosseous implants in human subjects.

PURPOSE: Transitional implants were designed to support provisional restorations and to allow for load-free osseointegration of conventional implants while a patient was provided with immediate esthetics and function. The purpose of this study was to evaluate the removal torque values of immediately loaded transitional implants in human subjects. MATERIALS AND METHODS: Thirty-one 1.8-mm-diameter transitional implants were placed in 4 patients to support provisional restorations and were subjected to immediate loading. Removal torque values were recorded using a modified ITI torque driver, which was calibrated on an Instron test machine. Torque values were subjected to analysis of variance and post hoc comparisons of means (P < .05). RESULTS: Twenty-six implants were removed intact with torque values between 10.5 and 22.9 Ncm, while 5 fractured at the bone crest at values between 27.1 and 35.4 Ncm. Mean torque values increased with time in function. These values were significantly lower in the maxilla (16.1 +/- 4.8 Ncm) than in the mandible (24.0 +/- 7.3 Ncm). DISCUSSION: Results suggest that these transitional implants may be safely removed from the maxilla after 7 to 15 months, but there is a risk of implant fracture during removal from the mandible after 10 months. CONCLUSION: Removal torque levels for these implants indicate varying degrees of integration even though they were subjected to immediate loading.

Aged↗
PubMed1996

Torque: an appraisal of misuse of terminology in chiropractic literature and technique.

OBJECTIVE: To assess the use of the term "torque" in the chiropractic literature and to analyze its usage in chiropractic technique procedures. DATA SOURCES, STUDY SELECTION AND DATA EXTRACTION: Articles were retrieved through literature searches of several indexing services [(MEDLINE, Index to Chiropractic Literature, Chiropractic Research Archives Collection (CRAC) and Chiropractic Literature Analysis and Retrieval System (ChiroLARS)] and hand searches in the technique section of a chiropractic college library. From textbooks, key terms included: Torque, Torsion, Biomechanics, Physics, Chiropractic, Nomenclature and Manipulation. For MEDLINE: Torque, Chiropractic Methods, Manipulation-Spinal Methods, Biomechanics, Nomenclature and Chiropractic Terminology. Texts and papers that discussed the word "torque" were reviewed for their association with the thrust of a spinal adjustment. Inferences of "torque" and its application were included to represent the present-day usage of the term in chiropractic. CONCLUSIONS: We believe that the term torque is misused in chiropractic literature. This misuse has been perpetuated in chiropractic college courses, student clinic examinations and state and national board examinations. We strongly suggest that references to the term torque that are not biomechanically correct must be removed from all such sources.

Chiropractic↗
PubMed1996

Velocity-dependent ankle torque in the normal rat.

We evaluated the velocity-dependent ankle torque and associated activity of the ankle extensor muscle stretch reflexes in normal rats. A 287% increase in velocity-dependent ankle torque was observed at the highest velocity tested compared with the lowest velocity. Low velocity torques were minimally altered during general anesthesia that depressed EMG activity by up to 90%. However, velocity-dependent torque during higher velocity ankle rotations (306-612 degrees s-1 correlated with parallel increases in EMG magnitude recorded from the triceps surae muscles. General anesthesia (pentobarbital) abolished 61% of the velocity-dependent ankle torque at 612 degrees s-1. We conclude that ankle torque and ankle extensor muscle activity display velocity enhancement over a broad range. These observations indicate that protocols designed to assess ankle torque in the rat should use instrumentation to produce a broad range of velocities up to at least 600 degrees s-1.

Anesthesia, General↗
PubMed1997

Assessment of primary and salvage lateral mass screw insertion torque in a cadaveric model.

This study was performed to determine the insertion torques of three types of lateral mass screws and to explore their relationship to bone mineral density (BMD). The peak insertion torque of primary articular screws was measured, and the holes were then stripped by overtightening. Larger diameter "salvage" screws were placed in the stripped holes, and peak insertion torque was measured. Peak primary screw insertion torque and BMD were positively correlated (r = 0.48, p = 0.00001). The ratio of salvage to primary screw insertion torque varied significantly among the systems (p = 0.0003). The positive correlation between BMD and primary screw peak insertion torque confirms the importance of bone density for satisfactory screw purchase. The large variation in the ratio of salvage to primary screw insertion torque among systems may be due to differences in primary and salvage screw design.

Bone Density↗
PubMed1993

Torque history of electrically stimulated human quadriceps: implications for stimulation therapy.

The time course of knee extension torque was measured in human quadriceps muscles during 30 min of transcutaneous neuromuscular electrical stimulation (NMES). Ninety subjects were divided into six experimental groups (n = 15 per group), which received stimulation at one of the following frequency/duty cycle combinations: 10 Hz/50%, 30 Hz/50%, 50 Hz/50%, 10 Hz/70%, 30 Hz/70%, and 50 Hz/70%. Two-way analysis of variance revealed that the magnitude of the relative torque decrease (the percentage of decrease in torque relative to the initial value) was significantly different between frequencies (p < 0.005) and duty cycles (p < 0.02), with no significant interaction (p > 0.6). Increasing either frequency or duty cycle caused a greater decrease in torque. In spite of this result, there was no significant difference between groups in the total activity (torque-time integral) achieved during the 30 min treatment session. The magnitude of this activity corresponded to only about 7-14 maximum voluntary contractions. Finally, the average torque during the treatment session was significantly different among groups (p < 0.001), being greatest for the 50 Hz/50% group and least for the 10 Hz/70% group. Taken together, these data suggest that a smaller number of longer duration contractions produces the greatest muscle tension. They also suggest that the absolute torque levels achieved with NMES are relatively low compared with voluntary muscular activity.

Adult↗
PubMed2003

Time and magnitude of torque generation is impaired in both arms following stroke.

Muscle strength, usually measured as the peak torque during maximal contraction, is impaired in persons with stroke. Time-dependent properties of muscle contraction may also be altered but have not been quantified. We quantified both magnitude (peak torque) and time-dependent parameters (times to develop and reduce torque) in eight different isometric joint actions. Parameters were compared among the more and less affected arms of 20 persons with chronic stroke and the nondominant arms of 10 similarly aged healthy persons. Torque-generation parameters were independent from one another (i.e., low correlations) and highly reliable between trials and days. All parameters were impaired in the more affected arm, whereas peak torque and time to develop torque were impaired in the less affected arm. Following stroke, torque-generation impairments include both magnitude and time-dependent properties and exist not only in the more affected but also in the less affected arm. Clinicians attempting to improve upper-extremity function should employ therapeutic exercises that challenge patients to improve both their strength and speed of muscle contraction.

Aged↗
PubMed1991

Functional torque-velocity and power-velocity characteristics of elite athletes.

Technical limitations of some isokinetic dynamometers have called into question the validity of some data on human muscle mechanics. The Biodex dynamometer has been shown to minimize the impact artefact while permitting automatic gravity correction. This dynamometer was used to study quadriceps muscle torque and power generation in elite power (n = 6) and elite endurance (n = 7) athletes over 12 randomly assigned isokinetic velocities from 30 degrees.s-1 to 300 degrees.s-1. The angle at peak torque varied as a negative, linear function of angular velocity, with the average angle across test velocities being 59.5 degrees (SD 10.2 degrees). Power athletes developed greater peak torque at each angular velocity (P less than 0.05) and experienced a 39.7% decrement in torque over the velocity range tested. Endurance athletes encountered a 38.8% decline in peak torque. Torques measured at 60 degrees of knee flexion followed a similar trend in both groups; however the greatest torques were recorded at 60 degrees.s-1 rather than at 30 degrees.s-1. Leg extensor muscle power increased monotonically with angular velocity in both power (r2 = 0.728) and endurance athletes (r2 = 0.839); however these curves diverged significantly so that the power athletes produced progressively more power with each velocity increment. These inter group differences probably reflected a combination of natural selection and training adaptation.

Adult↗
PubMed1997

Torque-velocity relationship during cycle ergometer sprints with and without toe clips.

The torque-velocity relationship in cycling has been studied during all-out sprints (n = 6 subjects) with and without toe clips on an electronic Lode ergometer with strain gauges, to estimate the importance of the expected decrease in torque, velocity and power output. As previously found with different cycling protocols, the torque-velocity relationship was linear for all-out sprints with toe clips. A similar relationship was observed when cycling without toe clips but the torque-velocity relationship was inflected downwards at low or high velocities in several subjects who were not regular cyclists. The pulling action during the rise of the pedal at low velocities cannot explain why the torque-velocity relationship is not hyperbolic for cycling exercises with toe clips because similar relationships were observed without toe clips. The maximal power output was significantly higher during cycling with toe clips (782 W vs 668 W, P < 0.05), probably because of the pulling action at low and medium velocities as indicated by the higher value of the extrapolated maximal torque T0 (138 N x m vs 122 N x m, P < 0.05). In contrast, the maximal extrapolated velocity, V0 and peak velocity were not significantly improved by the use of toe clips. The comparison of the angle-torque patterns at low and high velocities suggested that the kinetic energy of the legs can be transformed into power output when cycling without toe clips as well as it can when cycling with toe clips.

Adult↗
PubMed1982

Influence of arch shape on the transverse effects of transpalatal arches of the Goshgarian type during application of buccal root torque.

Previous studies reveal that the application of buccal root torque to upper molars by means of a transpalatal arch without appropriate adjustments of the arch width can produce, initially, an adverse buccal tipping of the molar crowns. Clinical observation suggests that the amount of this buccal crown tipping depends on the arch form of the palatal bar. In order to determine the influence of the arch width and height, an in vitro experiment was performed on the forces and moments produced by transpalatal arches of the Golshgarian type when symmetrical buccal root torque was applied. The torque moments and expansive lateral forces developed by nine different arch forms of varying height and width were measured and the corresponding moment-to-force ratios were calculated at three different torque levels. It was found that the moment-to-force ratio acting on the upper molars depended mainly on the amount of torque applied and the arch height. This indicates that when low palatal bars are used, the application of buccal root torque of clinically relevant amounts leads to an initial buccal crown tipping, whereas the same amounts of torque, when applied by means of high arches, bring about an initial buccal root tipping. The clinical implications of these findings are discussed.

Biomechanical Phenomena↗
PubMed1993

A static dynamometer measuring multidirectional torques exerted simultaneously at the hip and knee.

The function of a static dynamometer measuring torques exerted simultaneously in the different anatomical planes of the hip (flexion-extension, abduction-adduction and internal-external rotation) and knee (flexion-extension) is described. Muscular torques were calculated in real time using a desktop computer from measurements of orthogonal forces applied at two locations and the lever arm values measured in each subject. The reliability of the force transducers was explored by examining their output, using calibrated weights, on three different days. The results were identical over this period of time, indicating that the transducers are highly reliable. A mechanical simulator of a lower limb was constructed to generate specific or combined torques of known values at the hip and knee. The torques measured by the dynamometer were found to be highly concordant with the known torques applied by the simulator, indicating that the torque measurements were valid. The usefulness of the dynamometer is demonstrated by evaluating the activity of the rectus femoris and biceps femoris muscles during static efforts exerted in various directions at the hip. In addition, the mechanical action of biarticular muscles at the hip was evaluated by quantification of hip torques during efforts exerted at the knee. From these results, it has been concluded that the present biarticular and multidirectional dynamometer is a valid, reliable and precise instrument that may prove to be useful in evaluating the muscular function of the lower limb.

Biophysics↗
PubMed1995

Errors in alignment of center of pressure and foot coordinates affect predicted lower extremity torques.

The purpose of the study was to quantify the effect of errors in spatial alignment between the center of pressure recorded from a force platform and the coordinates of the foot recorded from film on resultant joint torques in the lower extremity during the stance phase of gait. Two-dimensional kinematic and kinetic data from eight subjects performing walking and running were analyzed using inverse dynamics with the obtained center of pressure values and with +/- 0.5 and +/- 1.0 cm shifts in the anteroposterior location of the center of pressure under the support foot. Shifting the center of pressure posteriorly increased the flexor (dorsiflexor) torques at the hip and ankle and decreased the extensor (plantarflexor) torques at these joints. This shift also caused an increase in the extensor and a decrease in the flexor torques at the knee. Shifting the center of pressure anteriorly caused the opposite effects at each joint. The +/- 0.5 and +/- 1.0 cm shifts in the location of the center of pressure caused, on average, 7 and 14% changes, respectively, in maximum joint torque and angular impulse values. Relative transition times between flexor and extensor torques were either increased or decreased, on average, by 7 and 13%, respectively for the two conditions over all trials. Based on these results, it is concluded that due to potential errors in the spatial alignment of kinetic and kinematic data, joint torques in the literature on gait should be considered as approximations of the true values.

Adult↗