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PubMed1992

Measurement of torque of trunk flexors at different velocities.

The purpose of this study was to determine the test-retest reliability of recording isometric and isokinetic torque of the trunk flexors and to examine the effect of velocity on the torque curves. Thirty healthy subjects were tested on two occasions for isometric torque of trunk flexion at four angles and eccentric and concentric torque at three velocities. Two subjects repeated these tests in the passive mode to determine the torque produced by the trunk when there was no active flexion effort. Intraclass correlation coefficients were above 0.85 for all isometric and isokinetic measures. Standard errors of measurement ranged from 6.9 to 19.5 Nm. Student t-tests indicated no significant differences between occasions for all outcome measures. Examination of passive and active torque curves indicated that the torque produced by the mass of the trunk increased with increasing velocity. It is concluded that both isometric and isokinetic testing of the trunk flexors are reliable, but that testing at higher velocities may not provide a valid measure of muscle performance.

Abdominal Muscles↗
PubMed1996

Effect of closed chain exercise on quadriceps femoris peak torque and functional performance.

OBJECTIVE: To determine the effect of a 6-week leg press training program on quadriceps femoris peak torque and lower extremity functional performance. DESIGN AND SETTING: A 2 x 3 factorial design. A private university-based outpatient physical therapy clinic was used for testing. The university strength and conditioning center was used for training sessions. SUBJECTS: A volunteer sample of thirty nonathletic, collegeage females participated. All thirty subjects completed the study. MEASUREMENTS: Subjects were randomly assigned to either a control group (G(con)) or an exercise group that performed isotonic unilateral leg presses through either 0 to 60 degrees (G(60)) or 0 to 90 degrees (G(90)) of knee flexion. Subjects trained 3 days/wk for 6 weeks using the DAPRE technique. Pre and post isokinetic testing of the quadriceps femoris at 60 degrees /sec and hop tests for distance and time were measured. RESULTS: Both training groups showed significant pre-post increases (p < .05) for: concentric peak torque, eccentric peak torque, and hop test for distance. G\(60) showed a significant decrease in hop test for time values. Significant increases (p < .05) in eccentric peak torque was seen between training groups and the control group, concentric peak torque was significantly greater only in G(90) as compared to G(con), on. No significant differences were observed between G(60) and G(90) for any of the measured variables. There were no differences between the three groups for any of the functional hop test measurements. CONCLUSIONS: Unilateral leg press exercise performed through 0 to 90 degrees of knee flexion increases concentric and eccentric peak torque while training from 0 to 60 degrees improves eccentric torque. No changes in functional performance as measured by hop tests were seen in any groups. Transference between closed kinetic chain (CKC) exercise and open kinetic chain testing was supported, but not between CKC and functional performance testing.

Journal Article↗
PubMed1991

Influence of two levels of caffeine on maximal torque at selected angular velocities.

The purpose of this study was to determine the effect of two doses of caffeine on peak torque and muscle endurance in the knee extensors and flexors. Twenty males and 16 females were randomly assigned to one of three groups: 600 mg caffeine, 300 mg caffeine, or a control receiving a placebo. Subjects with similar caffeine consumption history were used and all subjects abstained from caffeine usage for 24 hours prior to testing. Subjects were tested for maximal strength and endurance at 75, 180, and 300 degrees per second using a Cybex II Isokinetic Dynomometer interfaced with a Cybex Data Reduction Computer. After pretesting, each subject was given one of three solutions using a double-blind design. Following a one hour rest and absorption period, the subjects were again tested. Data were analyzed using a 3 x 2 repeated measures analysis of variance with a grouping factor at three levels (600 mg vs 300 mg vs 0 mg) and a trial factor at two levels (pre- vs posttest). The following variables were analyzed at all angular velocities: peak torque and subsequent joint angle, peak torque at 30 degrees, and peak torque at 70 degrees. At 300 degrees per second, the dependent variables were total torque for 15 repetitions, total torque for the first 3 repetitions, and total torque for the last 3 repetitions. The results indicated no significant changes from pre- to posttest. It was concluded that maximal strength and endurance was not affected by the two levels of caffeine used in this study and that caffeine may not be considered an ergogenic aid in strength output in subjects naive to resistance training.

Adult↗
PubMed1991

Torque development in isokinetic training.

Twenty men were randomized into three groups that performed maximal isokinetic knee extensions five days a week for 12 weeks; a fourth group was a control group. The training protocol was different for the opposite lower extremity of each subject, such that subjects in group I trained at 36 degrees/sec with 20 or 60 repetitions, group II did 20 repetitions at 36 degrees/sec with one limb and 60 repetitions at 108 degrees/sec contralaterally, and group III trained at 108 degrees/sec with 20 or 60 repetitions. Group IV did no training. Bilateral pretraining and posttraining vastus lateralis muscle biopsies were done, and maximal torque-velocity tests (0 degrees to 234 degrees/sec at 18 degrees/sec steps) were performed every two weeks. The muscle biopsies were examined for muscle-fiber area and enzyme activity. Statistical analysis of the torque-velocity curves showed that subjects who trained at 36 degrees/sec made significant overall gains in torque and significantly greater torque gains than those training at 108 degrees/sec. Torque gains were not made uniformly during the 12 weeks of training; they occurred primarily during the initial 4 to 8 weeks. There were no significant increases in muscle-fiber areas in response to training, but there were increases in glycolytic and mitochondrial enzyme activities. These findings suggest that the critical variable for developing strength (maximal torque), at least within the context of isokinetic training, is the amount of torque developed during training.

Adenosine Triphosphatases↗
PubMed1985

[Close interdependence between passive and active soleus muscle torques in man: approach to the coregulation of the number of sarcomeres and length of the connective tissue].

Soleus muscle has, to as great an extent as possible, been functionally isolated in man. A device previously described permitted measurement of the soleus torque as a function of the tibia-calcaneum angle, and not as a function of tibia-foot angle. This latter angle cannot be correctly related to soleus length, since the arch of the foot can not be considered as rigid throughout the experiment. Ankle movements were performed on a horizontal plane by successive increments of 5 degrees from full extension (plantar flexion) up to full flexion (dorsiflexion). Passive torques were measured for every angle. At the same angles, the total torques were recorded while the subject exerted a voluntary constant contraction which corresponded to 45% of the maximum integrated electromyographical activity of soleus muscle. The active torque-angle curve was obtained by subtracting, for the same angle, the passive from the total torques. It must be stressed that, when the muscle is maximally shortened, little or no torque was measured. For the angle corresponding to the top of the sub-maximal active curve (integrated electromyographic activity 45% of the maximum), the passive torque was about 1.75 Nm and showed no significant interindividual variations. This result contrasted with the marked interindividual shifts which affect both passive and active curves. This interdependence of passive and active curves in human soleus muscle is compatible with the results of a previous study in the cat showing the concomitant adaptations of sarcomere number and connective tissue length.

Calcaneus↗
PubMed1985

The relationships of functional capacity, pain, and isometric and isokinetic torque in osteoarthrosis of the knee.

Thirty-nine patients suffering from osteoarthrosis of the knee were repeatedly measured. The relationship was studied for two groups of variables. The first group consisted of subjective assessments of functional capacity and pain and a walking test. The second group consisted of isometric knee extension torque and isokinetic knee flexion and extension torque at 30 degrees/sec, 60 degrees/sec, 120 degrees/sec and 180 degrees/sec. High correlations between each of the static and dynamic torque values were found. Multiple regression analysis showed that isometric and isokinetic torque measures are unsatisfactory predictors of functional capacity, since only 23-35% of the variation of functional capacity, pain and walking test variables was explained by the variation of torque variables. Dynamic torque measurements had very little advantage over static torque tests. It is concluded that outcome measures in studies of osteoarthrosis should be problem-oriented and include direct assessments of functional capacity, pain and walking ability.

Female↗
PubMed1978

The influence of design on the transmission of torque across knee prostheses.

Knee prostheses of eight different designs were tested experimentally to determine the axial torque necessary to rotate the tibial component relative to the femoral component with the prosthesis positioned at or near full extension. The results represent transmitted torque as a function of axial rotation. For six designs, the transmitted torque was 11.3 newton-meters (100 inch-pounds) or greater at 6 degrees of rotation, with an axial load of 1556.8 newtons (350 pounds). These prostheses either had close conformation between femoral and tibial components, or were mechanically linked. In these prostheses, the geometry of the articulating surfaces was the primary determinant of torque. For the other two types, under similar loading conditions the transmitted torques were 2.5 newton-meters (twenty-two inch-pounds) at 6 degrees of rotation. These prostheses were designed to allow greater freedom for rotation, and hence for them the primary determinant of torque was friction between the articulating surfaces. The predictive value of this torque characteristic relative to the incidence of loosening will have to be determined by comparison with clinical experience.

Biomechanical Phenomena↗
PubMed1984

Isokinetic torque levels in hemophiliac knee musculature.

The purposes of this study were to 1) measure peak torques generated by knee extensors and flexors in hemophilia patients; 2) describe flexor to extensor; 3) record the point in the arc of motion where peak torque was achieved; 4) correlate results with age, degree of hemophilic arthropathy, and presence of flexion contracture; and 5) compare results with reports on healthy subjects. Forty-seven patients (94 knees) with severe hemophilia were tested with a Cybex II isokinetic dynamometer at a speed of 30 degrees per second. Height, weight, thigh girths, and passive knee range of motion were recorded. Standing roentgenograms of the knee were evaluated to assess degree of arthropathy. Subjects were divided into groups by age and degree of arthropathy. Descriptive statistics were generated for all groups. Average peak extensor and flexor torque was similar for adolescents and adults. Increasing degree of arthropathy was associated with significant decreases in both extensor and flexor torque, an increase in flexor to extensor ratios and increasing knee flexion contractures. Across all groups, flexor to extensor ratios were abnormally high, particularly in patients with type IV arthropathy. The point in arc of motion where peak torques occurred did not differ significantly across groups and compared favorably with measures reported in the literature. For all ages, mean peak extensor and flexor torques were less than values reported in the literature for healthy subjects. Results of this study demonstrate the profound decrease in torque produced by knee musculature in hemophilia patients, particularly those with more severe arthropathy and knee flexion deformity.

Adolescent↗
PubMed1983

Measurement of torque during passive and active ankle movements in patients with muscle hypertonia. A methodological study.

Torque curves were recorded during passive and active ankle joint movements at three preset angular velocities (30, 60 and 120 degrees/s) with the subject in the supine position and 45 degrees hip and knee angles. Recordings were performed in normal subjects (n = 11), patients with clinical spasticity (n = 10) and patients with Parkinson's disease (n = 7). The torque curves recorded during passive dorsiflexion followed by plantar flexion showed a counterclockwise hysteresis loop with minimal area in the normal subjects and a large area in patients, especially at the highest velocity. The torque increase during dorsiflexion was proportional to the angular velocity in the patients with spasticity but not in the patients with Parkinson's disease. In the patients with spasticity, a good correlation was found between clinical assessment of hypertonia and measurements of torque during passive movements but not torque values during maximal voluntary dorsiflexion. A model for data reduction and estimation of instant slope values on different parts of the torque-angle curve is suggested. The use of ankle torque recordings for evaluation of treatment effects is exemplified.

Adolescent↗
PubMed1980

Torque curves produced at the knee during isometric and isokinetic exercise.

Torque curves recorded during knee extension and flexion at various speeds of isokinetic effort and at selected positions of isometric effort were studied to determine the amount of torque generated at selected speeds of motion, the point in the arc of motion where maximal torque output occurred, the relationship between isometric and isokinetic torques, the relative value of knee flexion and extension torques at various speeds, and the constancy of results in isokinetic testing. The isokinetic torques produced were less than isometric values and decreased as the rate of motion increased. Production of peak torque output occurred later in the arc of motion as the speed of contraction increased in extension. No significant change in the relative ability of the flexors and extensors was seen as a rate of motion increased. Isokinetic test-retest differences were similar at the rates of motion tested.

Adult↗
PubMed1994

Knee disorders in carpet and floor layers and painters. Part I. Isometric knee extension and flexion torques.

Knee morbidity, knee extension torque and knee flexion torque were examined among 168 actively working carpet and floor layers and 146 painters. The study included a questionnaire concerning knee disorders and knee symptoms, a clinical examination of the knees and measurement of isometric knee extension and flexion torque. Knee accidents were reported more frequently by carpet and floor layers than by painters. Tenderness of the knees was noted to an equal extent in the two groups. Knee extension torques gradually decreased by increasing age among carpet and floor layers, but not among painters. Body weight and thigh girth were not related to age among carpet and floor layers, but gradually increased with age among painters. Analysis of covariance showed that the torques were most consistently related to thigh girth and age. In addition, the right knee extension torque was related to occupation and tenderness of the patellofemoral joint; the left knee extension torque was related to the knee pain index. These results suggest that occupational kneeling and internal derangement of the knee affect thigh muscles among actively working house builders.

Adult↗
PubMed1993

[Isokinetic torque of quadriceps in patients with untreated anterior cruciate ligament injury of the knee joint].

UNLABELLED: In order to study the role of muscle strength in patients with untreated anterior cruciate ligament (ACL) injury of the knee joint, the torque of the quadriceps was isokinetically measured during concentric contraction (CC) and passive eccentric contraction (PEC). The results were compared with those in normal individuals and sports players. Ninety patients with untreated ACL injury were subjected for the study. There were 50 men and 40 women. The normal group consisted of 20 students and the sports player group consisted of 20 soccer players. The peak torque and the torque at 30 degrees flexion of the quadriceps were isokinetically measured during CC and PEC by using a BIODEX machine. RESULTS: In patients with ACL injury, the peak torque was smaller in the injured side as compared with the uninjured side. At the same angle velocity, decrease of PEC in the injured side was larger than that of CC. These results were compared with the normal group and the sports player group. There was significant difference in the peak torque per body weight among each groups. But, the torque per body weight at 30 degrees flexion was almost consistent in these three groups. DISCUSSION: A considerable quadriceps atrophy occurs following ACL injury. In our experience, patients with functional absence of ACL are much more difficult to return to vigorous sports which require explosive eccentric contraction than to return to endurance sports which require repetitive concentric contractile efforts of the quadriceps. In the present study, decrease of the passive eccentric contraction in the injured side was more pronounced than that of the concentric contraction. From these results, the significantly decreased passive eccentric torque in the patients with untreated ACL injury can be a factor to cause instability of the knee joint in active daily life as well as in sports activities.

Adolescent↗
PubMed2004

Changes in voluntary torque and electromyographic activity following oral baclofen.

The consequences of baclofen intake on voluntary motor behaviors remain unclear. We studied the effects of single oral doses of baclofen on voluntary, isometric knee extension torques and surface and single motor unit (MU) electromyographic (EMG) activity from the vastus lateralis in 11 individuals without neurological injury. Examination of submaximal to maximal contractions of varying duration performed pre- and post-baclofen ingestion revealed significant decreases in maximal knee torques and EMG magnitude, accompanied by an increase in slope of the torque-EMG relation. A decreased slope of the torque-MU firing rate relation was also demonstrated post-baclofen, but without changes in minimal firing rates or recruitment forces. During sustained contractions at < or =25% of maximal voluntary torque elicited after baclofen ingestion, increased EMG activity was observed without significant differences in MU firing rates. Our results demonstrate a clear reduction in the maximal torque-generating ability following baclofen. Specific changes in MU firing patterns indicate that weakness may be due partly to reduced motoneuronal excitability, although use of MU discharge patterns to assess these effects is limited in its sensitivity.

Administration, Oral↗
PubMed1996

Effect of fatigue on maximal velocity and maximal torque during short exhausting cycling.

A group of 24 subjects performed on a cycle ergometer a fatigue test consisting of four successive all-out sprints against the same braking torque. The subjects were not allowed time to recover between sprints and consequently the test duration was shorter than 30 s. The pedal velocity was recorded every 10 ms from a disc fixed to the flywheel with 360 slots passing in front of a photo-electric cell linked to a microcomputer which processed the data. Taking into account the variation of kinetic energy of the ergometer flywheel, it was possible to determine the linear torque velocity relationship from data obtained during the all-out cycling exercise by computing torque and velocity from zero velocity to peak velocity according to a method proposed previously. The maximal theoretical velocity (v(0)) and the maximal theoretical torque (T(0)) were estimated by extrapolation of each torque-velocity relationship. Maximal power (P(max)) was calculated from the values of T(0) and v(0) (P(max) = 0.25v(0)T(0). The kinetics of v(0), T(0) and P(max) was assumed to express the effects of fatigue on the muscle contractile properties (maximal shortening velocity, maximal muscle strength and maximal power). Fatigue induced a parallel shift to the left of the torque-velocity relationships. The v( 0), T(0) and P(max) decreases were equal to 16.3 percent, 17.3 percent and 31 percent, respectively. The magnitude of the decrease was similar for v(0) and T(0) which suggested that P max decreased because of a slowing of maximal shortening velocity as well as a loss in maximal muscle strength. However, the interpretation of a decrease in cycling v(0) which has the dimension of a maximal cycling frequency is made difficult by the possible interactions between the agonistic and the antagonistic muscles and could also be explained by a slowing of the muscle relaxation rate.

Adult↗
PubMed1996

Influence of age on concentric isokinetic torque and passive extensibility variables of the calf muscles of women.

The purpose of this study was to investigate the influence of age on concentric isokinetic torque (CIT) and passive extensibility (PE) variables of the calf muscles of healthy women. Ten younger women [31.9 (SD 6.1) years] and ten older women [71.1 (SD 6.6) years] were tested using a KIN-COM 500H dynamometer. The PE was tested by stretching the muscles from relaxed plantarflexion to the maximal dorsiflexion (DF) angle at 5 degrees.s-1 without raw electromyogram (EMG) activity exceeding 0.05 mV. The maximal CIT was tested from the maximal DF angle 60 degrees into plantarflexion at four randomly ordered velocities of 30,60, 120, and 180 degrees.s-1. Separate analysis of variance (ANOVA) tests showed that the standardized (% body mass) concentric peak and mean torques were lower for the older women for all isokinetic velocities (p < 0.001). The "angular delay" from the onset of concentric activation to peak torque was smaller for the older women at 120 and 180 degrees.s-1 (p < 0.05). Age showed negative relationships (Pearson r) with all standardized peak torques (p < or = 0.001) and mean torques (p < 0.001), and the "angular delay" at 120 and 180 degrees.s-1 (p < or = 0.05). Independent t-tests showed that the maximal DF angle and the change in the PE angle from an initial angle (defined at 10% of the maximal passive torque) to the maximal DF angle were less for the older women (p < 0.05). Age was negatively related to the maximal DF angle and the change in the PE angle (p < 0.01). The results suggest an age-related decrease in calf muscle CIT, muscle length and PE. The smaller "angular delay" for the older women at 120 and 180 degrees.s-1 indicates that CIT testing at rapid velocities can be used to examine age-related changes in calf muscle contractile properties in relation to rapid velocities of movement.

Adult↗
PubMed2006

Position-dependent torque coupling and associated muscle activation in the hemiparetic upper extremity.

Previous studies have demonstrated abnormal joint torque coupling and associated muscle coactivations of the upper extremity in individuals with unilateral stroke. We investigated the effect of upper limb configuration on the expression of the well-documented patterns of shoulder abduction/elbow flexion and shoulder adduction/elbow extension. Maximal isometric shoulder and elbow torques were measured in stroke subjects in four different arm configurations. Additionally, an isometric combined torque task was completed where subjects were required to maintain various levels of shoulder abduction/adduction torque while attempting to maximize elbow flexion or extension torque. The dominant abduction/elbow flexion pattern was insensitive to changes in limb configuration while the elbow extension component of the adduction/extension pattern changed to elbow flexion at smaller shoulder abduction angles. This effect was not present in control subjects without stroke. The reversal of the torque-coupling pattern could not be explained by mechanical factors such as muscle length changes or muscle strength imbalances across the elbow joint. Potential neural mechanisms underlying the sensitivity of the adduction/elbow extension pattern to different somatosensory input resultant from changes in limb configuration are discussed along with the implications for future research.

Adult↗
PubMed2002

Relationship between passive properties of the calf muscles and plantarflexion concentric isokinetic torque characteristics.

The purpose of this study was to use a model of aging to examine the relationships between passive properties of the calf muscles and plantarflexion concentric isokinetic torque characteristics. Eighty-one active women 20-84 years of age were tested using a Kin-Com isokinetic dynamometer interfaced with electromyography (EMG). The passive properties were tested by stretching the muscles from relaxed plantarflexion to a maximal dorsiflexion (DF) angle at a rate of 5 degrees.s(-1) (0.087 rad.s(-1)) with minimal raw EMG activity (<0.05 mV). The maximal concentric torque was tested from maximal passive DF into plantarflexion at four randomly ordered velocities of 30, 60, 120, and 180 degrees.s(-1). Pearson correlation coefficients (Bonferroni adjusted) indicated a hierarchical order of high to moderate positive correlations between four passive properties and the peak and mean concentric torque for all test velocities. Correlation coefficients for the four passive properties ranged from 0.50 to 0.78 ( P<0.001), and the coefficients of determination ( r(2)) from higher to lower were: (1) maximal DF passive resistive torque ( r(2): 0.50-0.62), (2) length extensibility ( r(2): 0.40-0.49), (3) maximal muscle length ( r(2): 0.28-0.41), and (4) passive elastic stiffness in the last half of the full-stretch range of motion ( r(2): 0.25-0.31). The maximal DF passive resistive torque and the length extensibility accounted for 50-62% and 40-49% of the variability in the concentric torque, respectively. The results indicate that the concentrically stronger calf muscles of active women were positively correlated with passively stronger, longer, and stiffer calf muscles, which are characteristics of the calf muscles of younger women. Further studies are needed to examine whether therapeutic interventions, such as stretching and strengthening, can promote adaptations in the calf muscles of older women to attain these more youthful characteristics.

Adult↗
PubMed2002

Muscle force and muscle torque in humans require different methods when adjusting for differences in body size.

Different methods for adjusting muscle strength ( S) to normalise for differences in various estimates of body size [such as body mass ( m) or, infrequently, some other anthropometrical measurements] have been either proposed or applied when presenting the results of muscle function tests in various medical, ergonomic, and sport related studies. However, the fact that the relationship between S and body size may differ when muscle torque (measured using a standard isokinetic apparatus) and muscle force (measured using a dynamometer) are recorded has not been taken into account. To address this problem, we tested both muscle force and muscle torque under isometric conditions in six different muscle groups. The relationship assumed between S and m was S=k.m(b) and, according to a simple mechanical model based on geometrical similarity we developed, the exponential parameter b would be expected to equal 1.00 and 0.67 for torque and force, respectively. The experimentally obtained values for the parameter b were higher for muscle torque than for muscle force in five out of the six muscle groups tested ( P=0.068; Wilcoxon matched pairs test). Despite a relatively wide scatter, the mean (SD) values were also close to those predicted, being b=0.67 (0.19) (corresponding to the allometric scaling method) and b=1.02 (0.34) (corresponding to the ratio standards method) for muscle force and for muscle torque, respectively. Therefore, we concluded that the ratio standards and allometric scaling should be employed to adjust S for body size when muscle torque and muscle force, respectively, are tested.

Adult↗