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PubMedDate not supplied

Human torque velocity adaptations to sprint, endurance, or combined modes of training.

We had groups of athletes perform sprint and endurance run training independently or concurrently for 8 weeks to examine the voluntary in vivo mechanical responses to each type of training. Pre- and posttraining angle-specific peak torque during knee extension and flexion were determined at 0, 0.84, 1.65, 2.51, 3.35, 4.19, and 5.03 radian.sec-1 and normalized for lean body mass. Knee extension torque in the sprint-trained group increased across all test velocities, the endurance-trained group increased at 2.51, 3.34, 4.19, and 5.03 radian.sec-1, and the group performing the combined training showed no change at any velocity. Knee flexion torque of the sprint and combined groups decreased at 0.84, 1.65, and 2.51 radian.sec-1. Knee flexion torque in the sprint-trained group also decreased at 0 radian.sec-1 and in the combined group at 3.34 radian.sec-1. Knee flexion torque in the endurance-trained group showed no change at any velocity of contraction. Mean knee flexion:extension ratios across the test velocities significantly decreased in the sprint-trained group. Knee extension endurance during 30 seconds of maximal contractions significantly increased in all groups. Only the sprint-trained group showed a significant increase in endurance of the knee flexors. These data suggest that changes in the voluntary in vivo mechanical characteristics of knee extensor and flexor skeletal muscles are specific to the type of run training performed.

Adaptation, Physiological↗
PubMed1985

The instantaneous torque-angular velocity relation in plantar flexion during jumping.

Torques, angular velocities, and power of the ankle joint during plantar flexion were measured in jumping experiments in order to achieve insight into shape and magnitude of the instantaneous torque-angular velocity relation in a complex movement. Twelve trained subjects performed maximal vertical jumps from a semi-squatting position with 100 degrees of flexion in the knee joint. Ground reaction force measurements and film analyses were used to calculate instantaneous torques, angular velocities, and power outputs during plantar flexion. The shape of the instantaneous torque-angular velocity was different from the well-known hyperbolic force-velocity relation for isolated muscles. Maximal power output (2499 +/- 751 [SD] W) occurred at 60% of the mean maximal torque (301 +/- 62 N X m) and 80% of the mean maximal angular velocity (970 degrees/s). The maximal power output was six times larger than the power output reported in the literature for maximal isokinetic (monoarticular) plantar flexions. Influences like storage of energy in the series elastic component of Hill's muscle model and the role of polyarticular muscles in transporting energy from knee to ankle are discussed. It is concluded that many more selective studies will be necessary before it is possible to relate intrinsic muscle properties to the performance of muscles in poly-articular complex movements.

Ankle Joint↗
PubMed1994

Muscle torque changes caused by inertial exercise training.

Inertial exercise is a unique form of muscle loading with minimal data available regarding its use or efficacy. The purpose of this study was to describe a standardized clinical training program for inertial exercise using the Impulse system and to experimentally examine the influence of an inertial training program on muscle torque performance. The biceps brachii of 40 healthy subjects were pretested and posttested on the Lido Active dynamometer at 60 and 120 degrees/sec using the continuous passive motion mode. Subjects were randomly assigned to a control or training group. The training group exercised only the nondominant arm three times per week for 5 weeks on the Impulse system. Statistical analysis of peak torque measures between pretests and posttests of muscle torque was performed using a repeated measures analysis of variance design of one between-group (control vs. trained group) and three-within group (speed, arm, and movement; eccentric vs. concentric) factors. Posttraining peak torque measures for both the concentric and eccentric modes of exercise at 60 degrees/sec and for the eccentric mode at 120 degrees/sec were statistically significant at the p < .05 level. Complaints of muscle fatigue occurred during early training sessions, with no injuries and only minimal soreness reported. Inertial training appears to be an effective form of clinical muscular training that is measurable by muscle torque assessment.

Adult↗
PubMed1995

Relationship of isokinetic peak torque with work and power for ankle plantar flexion and dorsiflexion.

Past research has analyzed the relationship of peak torque with work and power on the muscles surrounding the knee with correlation coefficients being reported, ranging from .67 to .99. No studies to date have examined this relationship for muscles surrounding the ankle joint. The purpose of this study was to analyze the relationship of peak torque with work and power for the plantar flexor and dorsiflexor muscles of the ankle. Isokinetic data were collected from 15 healthy subjects (six males, nine females; mean age = 26.6 years) on an isokinetic dynamometer across two trials at speeds of 30 and 120 degrees/sec. The results of Pearson product moment correlations between peak torque to work and peak torque to power indicated correlation coefficients ranging from .81 to .97 for all speeds of testing and angular velocities. These findings suggest that peak torque is representative of work and power.

Adult↗
PubMed1975

[Torque load and types of fractures of threaded holes in cortical bone by lag screw. Mechanic and histological studies (author's transl)].

For the better understanding of fracture fixation by means of screws the torque load and types of fractures from threaded screw holes in cortical bone were studied. The experiments were performed on sheep tibia and femora in vitro and in vivo. We applied the 4.5 mm cortical bone screw (AISF) as lag screw. The screw was threaded in until total destruction of the thread occurred. The process of torque load was registered as a torque-angle of twist curve with 4 typical parts. Histologically in most cases shear fractures with different geometry occurred. In some cases we found conical geometric, and in others cylindrical geometric fragments in the threaded screw holes. The value of the torque at which destruction of a threaded hole occurs is a linear function of the thickness of the cortical bone. The gradient of this linear function is 6.6 kpcm/mm. In practical case, the insertional torque may be estimated by multiplying the cortical bone thickness in mm (if known) by a factor 4.

Animals↗
PubMed1988

Bed rest effect on extremity muscle torque in healthy men.

The purpose of this study was to assess the effect of bed rest on appendicular muscle torque. Fifteen healthy male volunteers between the ages of 21 and 54 participated in the study. The subjects were put on five weeks of strict horizontal bed rest. They were allowed to sit up for bowel movements only; however, no lower extremity weight-bearing was allowed. During bed rest, the subjects were required to ingest a fixed nutritionally adequate diet. Data for muscle torque were obtained using a Cybex II dynamometer, Upper Body Exercise Table (UBXT), and a data analysis computer (HUMAC). The subjects were tested on Cybex at the speed of 60 degrees/sec during the week before starting bed rest and the day after starting reambulation. The muscle groups tested were soleus, gastrocnemius-soleus, dorsiflexors, knee flexors, knee extensors, elbow flexors, and elbow extensors. The torque in all groups but elbow extensors was reduced by 24%, 26%, 8%, 8%, 19%, and 7%, respectively. Student's t-test for paired means demonstrated significant loss of torque in all muscle groups except elbow extensors (p less than 0.05). The results of this study suggest that a strengthening exercise program should be administered to these patients while they are on bed rest, and that the earliest possible attempt should be made to ambulate patients after prolonged bed rest to minimize the loss of muscle torque.

Adult↗
PubMed1979

Isokinetic torque levels for high school football players.

One hundred fifteen high school football players were screened isokinetically for the knee extensor and flexor torque generating capabilities and muscle imbalances. Each player was tested on a Cybex II at speeds of 30 degrees/sec and 180 degrees/sec. The subjects were stratified by age (15, 16, 17) and by position (linemen vs receivers and backs). Significant (p less than 0.05) torque differences were observed at both the slow and fast speeds for the knee extensors and flexors across the 3 age groups. However, the flexion to extension ratios did not differ significantly. On the other hand, when considering the positions, flexor torque and flexion to extension ratio at the slow speed were greater (p less than 0.05) for the linemen than the receivers and backs. Partial correlation analyses showed that body weight had the greatest effect on the knee torque values. It was concluded that basic torque measures differed with age and by position in the sport of football. Also, speed of movement altered the force generating capabilities of the muscle and resultant ratios.

Adolescent↗
PubMed1983

Frictional torque in surface and conventional hip replacement.

UNLABELLED: The frictional torque of the Trapezoidal-28 total hip replacement and the Tharies SR-3 and SR-5 surface replacements were measured in the University of California at Los Angeles hip-joint simulator in calf serum. Loads of as much as 890 newtons were applied while the femoral component oscillated through a 60-degree arc at forty cycles per minute. Frictional torque, as measured by a ring transducer at a fixed distance from the center of rotation, was seen to diminish as the thickness of the polyethylene increased and was found to be relatively proportional to the diameter of the femoral component. The torques measured in this study were found to be twenty to 100 times smaller than the static torques to failure for acetabular fixation that have been reported in the literature. Finally, no permanent deformation of the thin acetabular shells attributable to the cementing process was apparent when the recommended technique of surgical insertion was utilized. CLINICAL RELEVANCE: Surface replacement components have been shown to generate greater frictional torques at the acetabular bone-cement interface than do smaller-diameter conventional hip replacements. This indicates that the local mechanical-loading conditions of the hip joint are not the same for both types of replacements, and this should be considered when selecting the type of arthroplasty for an individual patient.

Biomechanical Phenomena↗
PubMed1980

Isokinetic and isometric torque relationships in the human body.

To study the relationship between isokinetic and isometric torque, maximum voluntary contractions were elicited from 352 male volunteers. Knee extensors, knee flexors, elbow extensors, and elbow flexors were tested isometrically and at isokinetic velocities of 30 degrees/sec, 90 degrees/sec, and 180 degrees/sec on a modified Cybex II apparatus. Isokinetic torque declined with increasing velocity of contraction. Intercorrelations of the isometric and isokinetic torque showed a moderate to high relationship between these 2 modes of testing. A higher relationship was noted between the isometric tests and the low-velocity isokinetic tests and between isokinetic velocities that were closest together. The correlations decreased as the isokinetic velocities became more widely separated. These data suggest that the torque elicited at low-velocity isokinetic contractions can be predictive of the torque elicited during isometric contractions. Faster velocities are less related to isometric strength.

Adolescent↗
PubMed1980

Active muscle torques about long-bone axes of major human joints.

Incorporaton of the activee muscle torques into the multisegmented total-human-body models can be considered the next major improvement of These models. The first step toward achievement of this goal is to obtain active muscle torque data about long-bone axes of major human joints. This paper presents results of research conducted to collect such data at the shoulder, hip, elbow, knee, and ankle joints. Active muscle torques were determined about the long-bone axes of the upper arm, upper leg, lower arm, and lower leg, which are the body segments associated with the major joints mentioned. Numerical results are presented for three male subjects for a specific number of body segment orientations with respect to the joints. It was concluded that, although there are intra- and inter-subject variations for the maximum values of the acrive muscle torques about long-bone axes, there are some trends one can establish for the behavior of the magnitudes of these torques.

Ankle Joint↗
PubMedDate not supplied

The relationship of Periotest values, biomaterial, and torque to failure in adult baboons.

A quantitative measure of implant stability would be beneficial to decision-making regarding the status of the bone anchorage around an implant. The Periotest device has been reported to provide such a measure, but the in vivo data are incomplete and inconclusive in support of this claim. The purpose of this study was to determine in an in vivo model the relationship between Periotest values (PTV), three different implant biomaterials, and torque to failure. A total of 79 screw-shape implants made of commericially pure titanium, titanium alloy, and HA-coated alloy were evaluated in the posterior maxillary and mandibular quadrants of six female baboons following healing for 3 to 4 months. At uncovering, the implants were tested with the Periotest device and torqued to failure using an electronic torque driver. Analysis of the PTV-biomaterial relationship revealed no significant difference among the implants based on the biomaterial (P = .7453). Analysis of PTV-torque revealed a significant relationship (P = .0117), however, the association between PTV and torque was not strong and does not explain 92% of the variation between the parameters (Pearson correlation .2823, R2 = .08).

Analysis of Variance↗
PubMed1993

Effect of preload and range of motion on isokinetic torque in women.

The purposes of this study were to compare the effects of two preload settings (0 N, 75 N) and two ranges of motion (5-90 degrees ROM, 25-70 degrees ROM) on torque output of the knee musculature. Twenty females were randomly assessed for isokinetic concentric (CON) and eccentric (ECC) torque of the knee extensor (EXT) and flexor (FLEX) musculature at a velocity of 1.62 rads.s-1. Two four-way ANOVAs (muscle x mode x range of motion x preload) revealed significant differences in average torque between the preload and range of motion conditions (CONEXT: 5-90 degrees ROM, 75 N = 74.3 +/- 17.2 Nm; 5-90 degrees ROM, 0 N = 68.3 +/- 17.2 Nm; 25-70 degrees ROM, 75 N = 79.0 +/- 13.0 Nm; 25-70 degrees ROM, 0 N = 71.5 +/- 20.8 Nm) (ECCEXT: 5-90 degrees ROM, 75 N = 85.6 +/- 28.6 Nm; 5-90 degrees ROM, 0 N = 82.8 +/- 27.8 Nm; 25-70 degrees ROM, 75 N = 97.7 +/- 23.4 Nm; 25-70 degrees ROM, 0 N = 93.6 +/- 26.5 Nm) (CONFLEX: 5-90 degrees ROM, 75 N = 43.5 +/- 9.2 Nm; 5-90 degrees ROM, 0 N = 43.1 +/- 5.6 Nm; 25-70 degrees ROM, 75 N = 44.2 +/- 8.9 Nm; 25-70 degrees ROM, 0 N = 41.2 +/- 8.9 Nm) (ECCFLEX: 5-90 degrees ROM, 75 N = 56.7 +/- 16.3 Nm; 5-90 degrees ROM, 0 N = 55.6 +/- 17.8 Nm; 25-70 degrees ROM, 75 N = 57.3 +/- 14.0 Nm; 25-70 degrees ROM, 0 N = 51.8 +/- 14.0 Nm) (P < 0.05). No differences in peak torque values were observed. Based on the findings of this study, preload and range of motion should remain constant between and among subjects if average torque is used as a criterion measure.

Adult↗
PubMed1997

Loss of twitch torque following muscle compression.

With the elbow flexed, compression of the human biceps brachii has been found to reduce twitch torque, with an approximately linear relationship being observed between the loss of torque and the applied pressure (up to 45 kPa). The decline in torque could no longer be demonstrated when the biceps muscle was stretched, by extending the elbow from a flexed position. The loss of torque in the flexed position appeared to be due to an inability of muscle sarcomeres to bulge sufficiently to take up the series elasticity at the fiber ends.

Adult↗
PubMed2001

Measurement of the force and torque produced in the calcium response of reactivated rat sperm flagella.

Rat sperm that are demembranated with Triton X-100 and reactivated with Mg-ATP show a strong mechanical response to the presence of free calcium ion. At pCa < 4, the midpiece region of the flagellum develops a strong and sustained curvature that gives the cell the overall appearance of a fishhook [Lindemann and Goltz, 1988: Cell Motil. Cytoskeleton 10:420-431]. In the present study, the force and torque that maintain the calcium-induced hook have been examined quantitatively. In addition, full-length and shortened flagella were manipulated to evaluate the plasticity of the hooks and determined the critical length necessary for maintaining the curvature. The hooks were found to be highly resilient, returning to their original configuration (>95%) after being straightened and released. The results from manipulating the shortened flagella suggest that the force holding the hook in the curved configuration is generated in the basal 60 microm of the flagellum. The force required to straighten the calcium-induced hooks was measured with force-calibrated glass microprobes, and the bending torque was calculated from the measured force. The force and torque required to straighten the flagellum were found to be proportional to the change in curvature of the hooked region of the flagellum, suggesting an elastic-like behavior. The average torque to open the hooks to a straight position was 2.6 (+/-1.4) x 10(-7) dyne x cm (2.6 x 10(-14) N x m) and the apparent stiffness was 4.3 (+/-1.3) x 10(-10) dyne x cm(2) (4.3 x 10(-19) N x m(2)). The stiffness of the hook was determined to be approximately one quarter the rigor stiffness of a rat sperm flagellum measured under comparable conditions.

Animals↗
PubMed2003

Effects of superimposed electrical stimulation on perceived discomfort and torque increment size and variability.

Superimposed electrical stimulation techniques can be used to detect central activation failure (CAF), that is, incomplete central nervous system recruitment or suboptimal activation of motor units. The purpose of this study was to evaluate the effects of two stimulation parameters on perceived discomfort and torque increment size and variability. Discomfort was evaluated using a visual analog scale (0-100 mm) for pain. The rectus femoris muscle of the dominant leg of 24 young healthy men was stimulated during submaximal (80% maximal) voluntary contractions. The size and variability of torque increments and perceived discomfort were assessed following stimulation with: (1) pulse trains (100 HZ, 150 V, 0.2-ms pulse duration) of different lengths (50 ms and 100 ms); and (2) pulse trains (100 HZ, 100 ms, 150 V) with different pulse durations (0.2 ms and 0.1 ms). Pulse trains of 100 ms generated larger torque increments and produced less variability, but caused more discomfort than pulse trains of 50 ms. Average discomfort ratings for pulse trains of 100 ms were 43.1 mm, and of 50 ms were 53.2 mm. There was no difference in torque increment size or in variability between pulse trains with pulse durations of 0.1 ms and 0.2 ms, whereas discomfort was less for the shorter pulse durations; average discomfort ratings were 53.1 mm and 58.1 mm for pulse durations of 0.1 ms and 0.2 ms, respectively. Thus, the appropriate selection of stimulation parameters can reduce discomfort but maintain the ability to detect CAF.

Adult↗
PubMed1997

Residues of the cytoplasmic domain of MotA essential for torque generation in the bacterial flagellar motor.

The MotA protein of Escherichia coli is a component of the flagellum that functions, together with MotB, in transmembrane proton conduction. MotA and MotB are believed to form the stator of the flagellar motor. They are integral membrane proteins; MotA has a large (ca 22 kDa) domain in the cytoplasm, and MotB a much smaller one (ca 3 kDa). Recent work suggests that cytoplasmically located parts of MotA and/or MotB might be present at the active site for torque generation in the motor. To test the proposal that the cytoplasmic domain of MotA functions in torque generation, and to identify the amino acid residues most important for function, we have carried out a mutational analysis of this domain. Using random mutagenesis, many mutations of cytoplasmic residues of MotA were isolated, which either abolish or impair torque generation. In most cases the residues affected are not conserved, and many of the replacements involve loss or gain of a proline residue, which suggests that these mutations disrupt function by altering the protein conformation rather than by directly affecting residues of an active site. Using site-directed mutagenesis, the conserved residues in the cytoplasmic domain of MotA were replaced, either singly or, in the case of charged residues, in various combinations. The results identify four residues of MotA that are important for motor function. These are Arg90 and Glu98, located in the cytoplasmic domain, and Pro173 and Pro222, located at the interface between the cytoplasmic domain and the membrane-spanning domain. Possible roles for these residues in torque generation are discussed.

Amino Acid Sequence↗
PubMed2005

Decrease of knee flexion torque in patients with ACL reconstruction: combined analysis of the architecture and function of the knee flexor muscles.

A decrease of deep knee flexion torque after anterior cruciate ligament (ACL) reconstruction, using a semitendinosus (and gracilis) tendon, has been reported. However, the cause of this weakness remains controversial. Architectural and functional differences in the knee flexor muscles influence this weakness. the fiber length of the semitendinosus, gracilis, semimembranosus, and biceps femoris were directly measured in six human cadavers. The flexion torque and EMG of the hamstrings were measured in both limbs of 16 patients (23+/-5 years) after ACL reconstruction (12-43 months post-operation), using ipsilateral semitendinosus tendon. Magnetic resonance imagings were taken, over both the thighs of those patients, to measure muscle volume and to confirm a state of semitendinosus tendon regeneration. The position of the musculotendinous junction of the semitendinosus was also analyzed. The fiber length of the semitendinosus and gracilis were three to four times longer than that of the semimembranosus and biceps femoris. The difference of flexion torque between the normal and ACL reconstructed limbs significantly increased as the knee flexion angle increased. The EMG value for the semimembranosus and biceps femoris of both limbs as well as the semitendinosus of the ACL reconstructed limbs, significantly reduced as the knee flexion angle was increased. The volume of the semitendinosus in the reconstructed limb was significantly smaller than in normal limbs. The regeneration of the semitendinosus tendon was confirmed in all subjects, and the musculotendinous junction position of the reconstructed limb in almost all subjects was found in further image from the knee joint space than that for the normal limb. The decrease of deep knee flexion torque, after ACL reconstruction, could be due to the atrophy and shortening of the semitendinosus after its tendon has been harvested, as well as the lack of compensation from the semimembranosus and biceps femoris, due to the architectural differences between the semitendinosus and the semimembranosus and biceps femoris.

Achilles Tendon↗
PubMed2002

Prehension synergies: effects of object geometry and prescribed torques.

We studied the coordination of forces and moments exerted by individual digits in static tasks that required balancing an external load and torque. Subjects ( n=10) stabilized a handle with an attachment that allowed for change of external torque. Thumb position and handle width systematically varied among the trials. Each subject performed 63 tasks (7 torque values x 3 thumb locations x 3 widths). Forces and moments exerted by the digit tips on the object were recorded. Although direction and magnitude of finger forces varied among subjects, each subject used a similar multidigit synergy: a single eigenvalue accounted for 95.2-98.5% of the total variance. When task parameters were varied, regular conjoint digital force changes (prehension synergies) were observed. Synergies represent preferential solutions used by the subjects to satisfy mechanical requirements of the tasks. In particular, chain effects in force adjustments to changes in the handle geometry were documented. An increased handle width induced the following effects: (a). tangential forces remained unchanged, (b). the same tangential forces produced a larger moment T (t), (c). the increased T (t) was compensated by a smaller moment of the normal forces T(n), and (d). normal finger forces were rearranged to generate a smaller moment. Torque control is a core component of prehension synergies. Observed prehension synergies are only mechanically necessitated in part. The data support a theory of hierarchical organization of prehension synergies.

Adult↗