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PubMed1987

Effect of inherent muscle length on isometric plantar flexion torque in healthy women.

This study investigated the relationship between inherent muscle length and torque production in 59 healthy women. We recorded nondominant ankle range-of-motion values for each subject. These values were partitioned into quartiles for two knee positions. Women with "loose" plantar flexor muscles comprised the first quartile, and those with "tight" plantar flexor muscles the fourth quartile. Tight- and loose-muscle groups were established for the 0-degree (fully extended) and 90-degree (flexed) knee test positions for data analysis. Torque measurements were obtained using an isokinetic testing apparatus. We asked each subject to perform a maximal isometric (static) plantar flexion contraction at each of three ankle positions: 7 degrees of dorsiflexion (angle A), 0 degrees or neutral (angle B), and 30 degrees of plantar flexion (angle C). Data analysis was performed using an analysis of variance for repeated measures. Results indicated that torque produced by the tight-muscle groups was significantly greater than the torque produced by the loose-muscle groups at both knee positions (p less than .05). Additionally, the ankle ROM data obtained suggest normative data different from those currently prevalent in the literature. Findings of this study may prove valuable in the rehabilitation of ankle injuries and could be beneficial especially to physical therapists in understanding more about normal ankle function.

Adolescent↗
PubMed1987

Relative decreases in knee extension torque with increased knee extension velocities in stroke patients with hemiparesis.

I examined the isokinetic knee extension torque (KET) produced by the paretic and nonparetic lower limbs of 27 stroke patients, with hemiparesis, at knee extension velocities (KEVs) of 30 degrees, 60 degrees, 120 degrees, and 180 degrees/sec. The purpose of this study was to determine whether the relative decreases in KET at velocities greater than 30 degrees/sec were different on the two sides. To further investigate this relative decrease, the relationship between the torque at 30 degrees/sec and those at higher speeds also was examined on each side. Relative decreases in KET differed between speeds, but not between sides. Torques at speeds greater than 30 degrees/sec were correlated significantly with the torque at 30 degrees/sec. These findings suggest that patients with hemiparesis and minimal muscle spasticity may have difficulty moving forcefully at higher speeds because they are weak. Therapeutic interventions, therefore, might be most beneficial when they are directed toward helping patients with hemiparesis activate their weak muscles.

Aged↗
PubMed1988

Comparison of maximal isometric hip abductor muscle torques between hip sides.

A posturally induced "stretch weakness" of the right hip abductor muscles has been reported in many healthy right-handed persons in the literature. The purpose of this study was to test for differences in the maximal isometric hip abduction torque produced between hip sides across multiple hip abduction angles. The torques were measured on 40 healthy right-handed individuals using a specialized torque-testing table at hip abduction angles of -10, 0, 10, 20, 30, and 40 degrees. Statistical analysis of the results did not demonstrate a specific "weakness" of the right hip abductor muscles at the hip angle used to clinically test them. The results, however, did demonstrate statistically significant differences in the torque-hip angle slopes across hip sides. We hypothesized that these slope differences may result from muscle adaptation to lengths imposed by standing posture. We discuss how manual muscle testing procedures may bias the likelihood of encountering stretch weakness in muscles that are habitually maintained at near-maximal elongation.

Adult↗
PubMed1989

Peak torque-to-body weight ratios in the trunk: a critical analysis.

The purpose of this study was to document the relationships between body weight and isokinetic extension and flexion peak torque produced by the trunk musculature. Using a dynamometer, we collected isokinetic measurements during trunk flexion and extension at speeds of 60 degrees and 120 degrees/sec on 61 healthy subjects (29 men, 32 women; 20-60 years old) while standing. Extension and flexion peak torque measurements were calculated for each subject at each speed. Male and female subjects' data were analyzed separately. Each subject's body weight was paired with peak torque at each speed, and Pearson product-moment correlation coefficients (r) were calculated. The correlation coefficients ranged from .27 to .39 for extension and from .66 to .70 for flexion, establishing a positive linear relationship between body weight and each of the isokinetic measurements. Body weight accounted for very small proportions of the variance (as low as 7%-15% in extension isokinetic measurements). In attempting to use a client's body weight to predict isokinetic peak torque measurements, the clinician should be aware that a great deal of unaccounted for variance exists. We recommend that clinicians use other variables (eg, activity level, age) in addition to body weight to control for individual differences among healthy subjects when measuring isokinetic trunk extension muscle performance.

Adult↗
PubMed1990

Reliability of isokinetic measurements of hip muscle torque in young boys.

The purpose of this study was to determine the reliability of measurements of hip muscle torque obtained with the Cybex II isokinetic dynamometer from healthy young boys. Twenty-nine healthy boys, aged 6 to 10 years, were tested two times at one- to two-week intervals. Torque of the hip flexors and extensors and the hip abductors and adductors was assessed at angular velocities of 30 degrees and 90 degrees/sec. The torque generated by each muscle group at 30 degrees/sec was similar to the torque generated at 90 degrees/sec. Intraclass correlation coefficients (ICCs) were used to determine test-retest reliability for measurements of each of the muscle groups at both angular velocities. The ICCs were higher for hip flexion and extension than they were for hip abduction and adduction. The highest ICC (ICC = .84) was found for hip extension at 90 degrees/sec. The ICCs for hip abduction and adduction at both angular velocities were less than .60. Factors that possibly contributed to the relatively low reliability in hip abduction and adduction are discussed.

Biomechanical Phenomena↗
PubMed1990

Relationship of extremity muscle torque and bone mineral density in postmenopausal women.

The purpose of this study was to examine the correlations between the torque of four extremity muscle groups and the bone mineral density (BMD) of the lumbar spine and hip in postmenopausal women. Fifty-six postmenopausal women (means age = 55.4 years, s = 7.1; means height = 162.6 cm, s = 6.4; means weight = 65.9 kg, s = 9.3) served as subjects. Bone mineral density was measured from the L2-L4 vertebral bodies, greater trochanter, femoral neck, and Ward's triangle using dual-photon absorptiometry. Hip abduction, knee extension, hip flexion, and grip force were assessed using the Spark Muscle Examination and Exercise Dosimeter (MEED) 3000 system. The Pearson product-moment correlations between muscle torque and BMD ranged from .07 to .42. The significant (p less than .05) correlations between torque and BMD (r = .27-.42) occurred in functionally and anatomically related areas. Results of this study demonstrate a statistically significant relationship between torque and BMD in anatomically related areas in postmenopausal women. This relationship, however, is not sufficiently strong to allow for prediction of BMD from the four muscle groups tested in this study. The relationship does suggest that strength may be a factor in the determination of BMD. Maintenance of strength in those muscle groups with anatomical or functional relationships to the hip and lumbar spine may play a role in the prevention and cessation of the osteoporotic changes that occur.

Body Weight↗
PubMed1991

Factors influencing quadriceps femoris muscle torque using transcutaneous neuromuscular electrical stimulation.

Quadriceps femoris muscle torque was measured in 40 subjects during transcutaneous neuromuscular electrical stimulation (NMES). Three different electrode types (carbonized rubber, sponge, and adhesive) were used on each subject, permitting determination of the factors that influenced the magnitude of quadriceps femoris muscle torque induced by NMES. This goal was accomplished by entering the various factors into a multiple-regression model. The electrodes differed significantly in their characteristics. The carbonized-rubber electrode delivered the greatest current with the lowest impedance, resulting in the highest knee extension torque. We found that the most important factor in determining torque generation level was the quadriceps femoris muscle's intrinsic ability to be activated (as opposed to electrode size, current, current density, or skin impedance). These data suggest that NMES efficacy is primarily determined by the intrinsic tissue properties of the individual (defined in this study as "efficiency") and is not dramatically changeable by using high stimulation currents or large electrode sizes. The precise physiological basis for interindividual differences in efficiency is not known.

Adult↗
PubMed1995

Relationship of plantar-flexor peak torque and dorsiflexion range of motion to kinetic variables during walking.

BACKGROUND AND PURPOSE: Limited ankle plantar-flexor moments and power during walking have been documented in several patient populations and are believed to contribute to gait deviations. The primary purpose of this study was to determine the relationship of plantar-flexor peak torque (PFPT) and dorsiflexion range of motion (ROM) to peak ankle moments and power during walking in a group of subjects without diabetes mellitus (DM) and in a group of subjects with DM and associated peripheral neuropathies. SUBJECTS: Nineteen subjects, 9 with DM and associated peripheral neuropathies (mean age = 58 years, SD = 14, range = 35-75 years) and 10 without DM (mean age = 57 years, SD = 11, range = 37-68 years), were evaluated. METHODS: The following data were collected on all subjects: PFPT, dorsiflexion ROM, and ankle moments and power during walking (using a two-dimensional link-segment model). Hierarchical multiple regression was used for data analysis. RESULTS: Plantar-flexor peak torque made substantial contributions to the ankle moment (40%) and ankle plantar-flexor power (53%) during walking. There also was a high correlation between PFPT and dorsiflexion ROM (r = .78) and between dorsiflexion ROM and ankle power (r = .72). CONCLUSION AND DISCUSSION: Plantar-flexor peak torque and dorsiflexion ROM are interrelated and appear to be important factors that contribute to ankle plantar-flexor moments and power during walking. This finding suggests that increasing PFPT and dorsiflexion ROM may help decrease gait deviations such as decreased step length and walking speed. When increasing PFPT is not possible, the natural occurrence of limited dorsiflexion ROM may help to maximize ankle moments during walking. Further research is needed to test whether these proposed treatment strategies can have a clinically useful effect. [Mueller MJ, Minor SD, Schaaf JA, et al. Relationship of plantar-flexor peak torque and dorsiflexion range of motion to kinetic variables during walking.

Adult↗
PubMedDate not supplied

Effect of cutting flute design on cortical bone screw insertion torque and pullout strength.

OBJECTIVE: To determine the effect of the number and length of cutting flutes on the insertion torque and pullout strength for self-tapping 4.5-millimeter cortical bone screws. DESIGN: Screws were self-tapped in the diaphysis of human cadaver femurs. Each of the six screw types studied had different designs with varying cutting flute lengths and numbers. Bone mineral density, insertion torque, and pullout strength were measured. SETTING: The study was conducted at an experimental biomechanics laboratory associated with a university medical center. OUTCOME MEASUREMENTS: Insertion torque and pullout strength were normalized by the local bone mineral density. RESULTS: The mean normalized insertion torque of the design with four full-length cutting flutes was less than the design with three full-length flutes and the two designs with one-third length flutes (p < 0.05). The mean normalized pullout strength of the screw with four full-length flutes was significantly greater than that of all screws with fewer than three flutes (p < 0.05). CONCLUSIONS: Priorities for a cutting flute design should ideally include ease of screw insertion, minimal soft tissue irritation, and maximal screw holding power. Screws with more than two flutes were easier to insert and did not cause cortical damage during insertion. The screw with four full-length flutes showed a trend toward being the easiest to insert and having the greatest holding strength.

Biomechanical Phenomena↗
PubMed1996

Age, fat-free weight, and isokinetic peak torque in high school female gymnasts.

The purpose of this study was to examine the covariate influence of fat-free weight (FFW) on age-related increases in isokinetic peak torque for leg flexion and extension in high school female gymnasts. Seventy-two gymnasts (X age +/- SD = 15 7 +/- 1.2 yr) volunteered to be measured for isokinetic leg flexion and extension strength using a calibrated Cybex II dynamometer at 30, 180, and 300 degrees*s(-1) as well as for body composition from underwater weighing. The results indicated that there were significant (P < 0.05) zero-order correlations for age versus leg flexion (r = 0.36-0.47) and extension (r = 0.51-0.57) peak torque, as well as FFW versus leg flexion (r = 0.50-0.66) and extension (r = 0.620.73) peak torque. There were also significant (P < 0.05) first-order partial correlations between age and peak torque (covaried for FFW) for leg extension at 30 (r = 0.25), 180 (r = 0.36-0.39), and 300 degrees*s(-1) (r = 0.25-0.28) but not for leg flexion. These findings indicated that for the high school female gymnasts in the present study, there were age-related increases in strength that could not be accounted for by changes in FFW. It is possible that factors such as an increase in muscle mass per unit of FFW and/or neural maturation contribute to strength increases during adolescence in female athletes.

Adolescent↗
PubMed1989

Comparison of compression and torque measurements of self-tapping and pretapped screws.

The choice of an internal fixation system for maxillofacial surgery is made difficult because of lack of information with respect to functional load. This study attempted to clarify some of the controversy with respect to maxillofacial use of these implants. Maximal compressive force to torque values were measured in standardized bone thicknesses of 1, 2, 3, and 4 mm. The screws tested were pretapped AO 1.5-, 2.0-, 2.7-, and 3.5-mm rescue screws and self-tapping Luhr, Champy, and AO 1.5- and 2.0-mm screws. Ten measurements were made for each screw type/bone thickness combination using a piezoelectric washer and torque screwdriver. It was apparent that for 1- and 2-mm bone thicknesses the use of self-tapping screws resulted in the highest compression values. In 3- and 4-mm bone thicknesses, pretapped screws offered the highest compression values. As expected, self-tapping screws had the highest torque values on insertion owing to torque loss in cutting the screw threads. The 2.7-mm screw offered no advantage over the 2.0-mm screws in 1- and 2-mm bone thicknesses but resulted in higher compression values in 3- and 4-mm bone thicknesses.

Animals↗
PubMed1990

The effect of facet geometry on the axial torque-rotation response of lumbar motion segments.

The objective of this study is to examine the effect of the facet geometry on the axial torque-rotation response of lumbar motion segments. The three-dimensional facet geometry of 35 L2-3 and 35 L4-5 specimens has been quantified in terms of seven parameters from computed tomographic transverse sections taken at 2-mm intervals. The motion segments have then been subjected to axial torque, for a variety of preload conditions, to establish the axial torque-rotation response. There exists significant variation of facet geometry between the segment levels; however, the degree of facet asymmetry is identical for each level. No significant correlation exists between the lumbar facet geometry and the axial torque-rotation response. The facet joints do, however, act as a "positive stop" to axial rotation, regardless of their orientation. Therefore, axial rotation sufficient to cause disc injury may only be possible after facet failure.

Cadaver↗
PubMed1993

Isometric maximal and submaximal trunk extension at different flexed positions in standing. Triaxial torque output and EMG.

Thirty-one healthy men were tested for the effects of trunk-flexion positions (0 degrees, 15 degrees, and 35 degrees) in standing on triaxial torques and electromyogram of 10 trunk muscles during voluntary maximal and submaximal isometric trunk extension. At a more flexed position, both erector spinae and latissimus dorsi showed significantly higher RMS-EMG. The abdominal obliques were coactivated only during 100% maximum voluntary exertion at each posture. In all tests, the rectus abdomini were quiet. Mean maximum extension torque increased significantly at 15 degrees and 35 degrees of trunk flexion. The ratio of extension torque over RMS-EMG of the trunk extensor muscles, called the neuromuscular efficiency ratio (NMER), also increased in the more flexed posture. However, NMER has to be interpreted with caution because it is affected both by posture and exertion levels. The effects of posture on the torque generation capability of the trunk question the validity of the current lifting recommendations.

Abdominal Muscles↗
PubMed1994

Effect of preload torque on the ultimate tensile strength of implant prosthetic retaining screws.

The preload concept proposes that an optimal torque exists to which implant prosthetic retaining screws should be tightened. According to this theory, the preload prevents separation of implant components, thus protecting the screw from fracture. Recent research suggests that most implant-retained prostheses in function today were placed using improper preloads. The purpose of this investigation was to determine whether or not improper preloading of prosthetic implant-retaining screws would adversely affect their ultimate tensile strength. Fifteen Nobelpharma-slotted gold screws from one lot were tightened to 6, 10, and 15 N/cm with a torque gauge and ultimate tensile strength values determined. The procedure was duplicated using 15 Nobelpharma gold screws from another lot tightened to 0, 10, and 20 N/cm. Within each of the test groups, there was no significant difference in the ultimate tensile strength among the three preload torques. However, a paired t test (P = 0.005) determined that there was a significant difference between the two lots with respect to the ultimate tensile strength of the screws preloaded to 10 N/cm. Altering the preload torque applied to Nobelpharma gold-retaining screws does not affect their ultimate tensile strength. The ultimate tensile strength of the screws from the two lots differed, suggesting an unannounced change in component specifications.

Dental Implants↗
PubMed2005

Radiation torque on a birefringent sphere caused by an electromagnetic wave.

We present an exact ab initio calculation of the optical torque on a spherical uniaxially birefringent particle of arbitrary size illuminated by plane electromagnetic wave of arbitrary polarization mode and direction of propagation. The calculation is based on the extended Mie theory and the Maxwell stress tensor formalism. The expression for evaluating radiation torque is derived for arbitrary (absorbing and lossless) isotropic surrounding medium. The dependence of the optical torque on the incident angle, the polarization mode, the material birefringence, as well as the particle size, has been systematically investigated. For normal illumination, namely, with the incident wave vector perpendicular to the extraordinary axis (EA) of the particle, the optical torque caused by a linearly polarized (LP) incident wave always shows the angle dependence . Here, is the angle between the EA and the incident electric field, whereas may take positive or negative values, dependent on , and the particle size. In the small particle limit, versus particle radius displays different power law behaviors, and , for LP and circularly polarized (CP) incident waves, respectively, while for small material birefringence , linear and square laws, and , are found for the LP and the CP incident modes, respectively.

Journal Article↗
PubMed2003

Torque on an ideal plasma.

Ripples in the confining field may exert a torque on a rotating plasma. Time reversal symmetry implies that this torque should vanish for an ideal plasma. However, even in an apparently ideal plasma, singularities can give rise to a nonzero torque. This torque is evaluated for a simple configuration. Although the primary force is magnetic, an essential contribution arises from other nonlinear terms in the equations of motion. The net force is confined to the singular layer, in the direction of the ripple wave vector and related to the energy absorbed in the layer.

Journal Article↗
PubMed1992

Longitudinal study on torque transmitted from a denture base to abutment tooth of a distal extension removable partial denture with circumferential clasps.

Not only forces but also torque exerted on abutment teeth are important factors for planning the construction of distal extension removable partial dentures. The purpose of this study was to make longitudinal analysis of torque transmitted from denture base to a direct abutment tooth of these dentures with circumferential clasps. The results are summarized as follows: (i) Vertical Max. MT (maximal mean value of torque) was decreased and became constant after one or one and half months of the insertion of new dentures. (ii) Lateral Max. MT in one subject was changed from the lingual direction to the buccal direction while in another subject it was constant. (iii) In the vertical direction, there were no remarkable differences of Max. MT and Ave. T (average value of torque) between subjects. Max. MT was 5-10 x 10(-3) kgm-1 in the downward. Ave. T was 2-3 x 10(-3) kgm ss-1 in the downward and 0.3 x 10(-3) kgm ss-1 in the upward. (iv) In the lateral direction, there were considerable differences of Max. MT and Ave. T between subjects. Max. MT was less than 20 x 10(-3) kgm. Ave. MT was 2-8 x 10(-3) kgm ss-1.

Aged↗
PubMed1995

Intramuscular pressure and torque during isometric, concentric and eccentric muscular activity.

Intramuscular pressures, electromyography (EMG) and torque generation during isometric, concentric and eccentric maximal isokinetic muscle activity were recorded in 10 healthy volunteers. Pressure and EMG activity were continuously and simultaneously measured side by side in the tibialis anterior and soleus muscles. Ankle joint torque and position were monitored continuously by an isokinetic dynamometer during plantar flexion and dorsiflexion of the foot. The increased force generation during eccentric muscular activity, compared with other muscular activity, was not accompanied by higher intramuscular pressure. Thus, this study demonstrated that eccentric muscular activity generated higher torque values for each increment of intramuscular pressure. Intramuscular pressures during antagonistic co-activation were significantly higher in the tibilis anterior muscle (42-46% of maximal agonistic activity) compared with the soleus muscle (12-29% of maximal agonistic activity) and was largely due to active recruitment of muscle fibers. In summary, eccentric muscular activity creates higher torque values with no additional increase of the intramuscular pressure compared with concentric and isometric muscular activity.

Adult↗