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PubMedDate not supplied

Critical bending moment of implant-abutment screw joint interfaces: effect of torque levels and implant diameter.

PURPOSE: Critical bending moment (CBM), the moment at which the external nonaxial load applied overcomes screw joint preload and causes loss of contact between the mating surfaces of the implant screw joint components, was measured with 2 types of implants and 2 types of abutments. MATERIALS AND METHODS: Using 4 test groups of 5 implant-abutment pairs, CBM at the implant-abutment screw joint was measured at 25%, 50%, 75%, and 100% of the manufacturer's recommended torque levels. Regular Platform (RP) Nobel Biocare implants (3.75 mm diameter), Wide Platform (WP) Nobel Biocare implants (5.0 mm diameter), CeraOne abutments, and Multiunit abutments were used. Microstrain was measured as loads were applied to the abutment at various distances from the implant-abutment interface. Strain instrumentation logged the strain data dynamically to determine the point of gap opening. All torque applications and strain measurements were repeated 5 times. RESULTS: For the CeraOne-RP group, the mean CBMs were 17.09 Ncm, 35.35 Ncm, 45.63 Ncm, and 62.64 Ncm at 25%, 50%, 75%, and 100% of the recommended torque level, respectively. For the CeraOne-WP group, mean CBMs were 28.29 Ncm, 62.97 Ncm, 92.20 Ncm, and 127.41 Ncm; for the Multiunit-RP group, 16.08 Ncm, 21.55 Ncm, 34.12 Ncm, and 39.46 Ncm; and for the Multiunit-WP group, 15.90 Ncm, 32.86 Ncm, 43.29 Ncm, and 61.55 Ncm at the 4 different torque levels. Two-way analysis of variance (ANOVA) (P < .001) revealed significant effects for the test groups (F = 2738.2) and torque levels (F = 2969.0). DISCUSSION: The methodology developed in this study allows confirmation of the gap opening of the screw joint for the test groups and determination of CBM at different torque levels. CONCLUSION: CBM was found to differ among abutment systems, implant diameters, and torque levels. The torque levels recommended by the manufacturer should followed to ensure screw joint integrity.

Analysis of Variance↗
PubMed1993

Control of torque direction by spinal pathways at the cat ankle joint.

To study the biomechanics of the calcaneal tendon's complex insertion onto the calcaneus, we measured torque-time trajectories exerted by the triceps surae and tibialis anterior muscles in eight unanesthetized decerebrate cats using a multi-axis force-moment sensor placed at the ankle joint. The ankle was constrained to an angle of 110 degrees plantarflexion. Muscles were activated using crossed-extension (XER), flexion (FWR), and caudal cutaneous sural nerve (SNR) reflexes. Torque contributions of other muscles activated by these reflexes were eliminated by denervation or tenotomy. In two animals, miniature pressure transducers were implanted among tendon fibers from the lateral gastrocnemius (LG) muscle that insert straight into the calcaneus or among tendon fibers from the medial gastrocnemius (MG) that cross over and insert on the lateral aspect of calcaneus. Reflexively evoked torques had the following directions: FWR, dorsiflexion and adduction; SNR, plantarflexion and abduction; and XER, plantarflexion and modest abduction or adduction. The proportion of abduction torque to plantarflexion torque was always greater for SNR than XER; this difference was about 50% of the magnitude of abduction torque generated by tetanic stimulation of the peronei. During SNR, pressures were higher in regions of the calcaneal tendon originating from MG than regions originating from LG. Similarly, pressures within the MG portion of the calcaneal tendon were higher during SNR than during XER, although these two reflexes produced matched ankle plantarflexion forces. Selective tenotomies and electromyographic recordings further demonstrated that MG generated most of the torque in response to SNR, while soleus, LG, and MG all generated torques in response to XER.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1996

The relationship between maximal power and maximal torque-velocity using an electronic ergometer.

Eight subjects performed a single allout sprint on a cycle ergometer with strain gauges bonded to the cranks. The crank angle-torque curves of the left and right legs were recorded during ten revolutions using the software package supplied with the ergometer. Torque data were stored every 2 degrees (180 angletorque data per pedal revolution for each leg). The ergometer was used in the linear mode with the lowest available linear factor (F1 = 0.01). In this mode, the braking torque (TB) was proportional to cycling velocity v(TB = F1v) and mechanical power was equal to F1v2. The relationship between the torque averaged over one revolution and the average velocity of one pedal revolution was studied during the acceleration phase of short allout exercise on an electronic ergometer (eight subjects) and a friction-loaded ergometer (four subjects). The present study showed that it is possible to determine the maximal torque-velocity relationship and to calculate maximal anaerobic power during a single allout sprint using an electronic cycle ergometer provided that strain gauges are bonded to the cranks. The torque-velocity relationships calculated were linear as for a friction loaded ergometer. As expected, the values of torque and maximal power measured with the strain gauges were higher than the corresponding values computed from the data collected during an allout test on a friction loaded ergometer. The torque-angle data collected during a single allout cycling exercise would suggest that angular accelerations of the leg segments and gravitational forces play the main role at high velocity.

Adult↗
PubMed1983

A comparison of peak and constant angle torque-velocity curves in fast and slow-twitch populations.

Peak and constant angle torque-velocity (T-V) curves were measured on a group of fast-twitch (FT, n = 10) and slow-twitch (ST, n = 6) subjects using a Cybex dynamometer. The T-V curve was plotted from 10 randomly assigned velocities ranging from 0.52 to 5.24 rad s-1 (30 to 300 degrees s-1). Each subject was tested four times with at least 24 h between testing sessions. Torque-velocity curves were plotted from the peak torque generated throughout the range of motion and from torque produced at a constant angle (150 degrees). When all subjects were combined into a single group, no significant difference existed between the normalized T-V curves even though they differed significantly in absolute amounts. When subjects were grouped according to muscle fiber type the T-V curves produced from constant angle torque differed significantly while those generated from peak torque did not. This finding suggests that T-V curves generated from peak torque are not as sensitive to influences produced by muscle fiber type as those curves generated from constant angle torque.

Adult↗
PubMed1996

A functional knee brace alters joint torque and power patterns during walking and running.

Individuals with anterior cruciate ligament (ACL) injury use greater extensor torques at the hip and ankle and lower extensor torques and joint power at the knee during gait compared to healthy subjects. These adaptations may be mediated by (1) altered neuromuscular strategies due to the injury, (2) training effects produced by rehabilitation protocols, and (3) training effects due to the functional knee brace (FKB) used during rehabilitation. The purpose of the study was to test the hypothesis that a FKB can cause individuals to walk and run with the torque and power patterns observed in rehabilitated ACL-injured individuals. Ten healthy subjects were tested walking and running with and without a FKB. Kinematic and ground reaction data were collected and combined with inverse dynamics to estimate the joint torques and powers. Data were analyzed with a two-way repeated measures ANOVA (gait vs knee condition). In walking, the hip and ankle extensor torques were 14.3% (p < 0.038) and 5.1% (p < 0.003) greater with FKB. In running, the hip extensor torque was 17.0% greater with FKB (p < 0.023). Knee torque was not different between conditions. In walking, the work performed at the hip and knee were 11.6% greater (p < 0.013) and 17.7% lower with FKB (p < 0.025), respectively. Results supported the hypothesis and it was concluded that a FKB may be one causative factor in the development of the unique joint torque and power patterns seen in ACL-injured gait.

Adult↗
PubMed2004

Correlation of interference screw insertion torque with depth of placement in the tibial tunnel using a quadrupled semitendinosus-gracilis graft in anterior cruciate ligament reconstruction.

PURPOSE: To evaluate the insertion torque of a soft-tissue interference screw in relation to depth of insertion into the tibial tunnel when used for fixation of a quadrupled semitendinosus-gracilis autograft in anterior cruciate ligament reconstruction. TYPE OF STUDY: Biomechanical cadaver study. METHODS: Ten quadrupled semitendinosus-gracilis grafts were harvested from fresh-frozen cadaver knees and fixed in donor proximal tibias using 10-mm bioabsorbable interference screws (Arthrex, Naples, FL). A cannulated torque screwdriver was used to measure screw insertion torque at 3 depths in the tibial tunnel: the outer cortex (distal third), the articular surface (proximal third), and between these 2 points (middle third). RESULTS: The mean insertion torques for the distal third, middle third, and proximal third were 8.7, 4.7, and 4.3 in/lb, respectively. The insertion torque was significantly higher at the outer cortex (distal third) than the middle third and proximal third (joint line of the tibial tunnel) ( P < .05). CONCLUSIONS: Our results indicate a correlation between insertion torque and depth of placement of bioabsorbable interference screws used for fixation of a semitendinosus-gracilis graft. Lower insertion torque at the articular surface, resulting in lower peak load or pullout strength, may outweigh the proposed benefits of joint-line fixation of a semitendinosus-gracilis graft used for anterior cruciate ligament reconstruction. CLINICAL RELEVANCE: Studies have suggested that anatomic proximal fixation of ACL grafts in the tibial tunnel produces stability similar to intact knees. The results of our study indicate that lower insertion torque at the articular surface results in lower peak load and pullout strength of the graft, which may outweigh the proposed benefits of joint-line fixation.

Adult↗
PubMed2005

Automatic analysis of cerebral asymmetry: an exploratory study of the relationship between brain torque and planum temporale asymmetry.

Leftward occipital and rightward frontal lobe asymmetry (brain torque) and leftward planum temporale asymmetry have been consistently reported in postmortem and in vivo neuroimaging studies of the human brain. Here automatic image analysis techniques are applied to quantify global and local asymmetries, and investigate the relationship between brain torque and planum temporale asymmetries on T1-weighted magnetic resonance (MR) images of 30 right-handed young healthy subjects (15 male, 15 female). Previously described automatic cerebral hemisphere extraction and 3D interhemispheric reflection-based methods for studying brain asymmetry are applied with a new technique, LowD (Low Dimension), which enables automatic quantification of brain torque. LowD integrates extracted left and right cerebral hemispheres in columns orthogonal to the midsagittal plane (2D column maps), and subsequently integrates slices along the brain's anterior-posterior axis (1D slice profiles). A torque index defined as the magnitude of occipital and frontal lobe asymmetry is computed allowing exploratory investigation of relationships between this global asymmetry and local asymmetries found in the planum temporale. LowD detected significant torque in the 30 subjects with occipital and frontal components found to be highly correlated (P<0.02). Significant leftward planum temporale asymmetry was detected (P<0.05), and the torque index correlated with planum temporale asymmetry (P<0.001). However, torque and total brain volume were not correlated. Therefore, although components of cerebral asymmetry may be related, their magnitude is not influenced by total hemisphere volume. LowD provides increased sensitivity for detection and quantification of brain torque on an individual subject basis, and future studies will apply these techniques to investigate the relationship between cerebral asymmetry and functional laterality.

Adult↗
PubMed1997

Shoulder rotator torque and wheelchair dependence differences of National Wheelchair Basketball Association players.

OBJECTIVE: Shoulder rotator muscle imbalances can contribute to subacromial impingement. The forces and movement patterns of wheelchair locomotion may contribute to these imbalances. This study attempted to determine whether National Wheelchair Basketball Association players of differing classifications had significant differences (p < or = .05) in concentric isokinetic peak shoulder rotator torque and torque ratios, and wheelchair locomotion dependence. DESIGN: Fifty-seven (class 1 = 12, class 2 = 24, class 3 = 21) of 117 total tournament participants (class 1 = 25, class 2 = 49, class 3 = 43) served as the convenience sample of volunteers for the survey portion, and 33 of these subjects (class 1 = 11, class 2 = 12, class 3 = 10) also entered the isokinetic portion of this study. SETTING: National wheelchair basketball tournament. RESULTS: Class 1 and 2 players had greater wheelchair dependence than class 3 players (p < or = .05). Peak torque or torque ratios generally did not differ among player classifications or with other populations. Class 1 players had weaker nondominant shoulder external rotator torque production at 60 degrees/sec (p < or = .03) compared with other classes and at 180 degrees/sec compared with class 3 players (p = .02), suggesting an inability to develop the "attenuation of dominance" noted among other groups. Diminished torque-producing capacity at 60 degrees/sec related to greater wheelchair dependence among class 1 players (p = .034). CONCLUSIONS: Class 1 players failed to demonstrate the acquired shoulder external rotator torque symmetry evident among class 2 and 3 players (with specific weakness of the nondominant shoulder external rotators). This torque symmetry difference was related to their greater dependence on wheelchair locomotion.

Adult↗
PubMed2001

Training-related changes in the maximal rate of torque development and EMG activity.

This study monitored the effects of a short-term elbow flexor training program on surface electromyographic (SEMG) spike activity. The experimental paradigm consisted of three test sessions separated by 2-week intervals. At the beginning of each session, participants (N=13) performed five maximal effort isometric contractions of the elbow flexors to serve as baseline. After 5 min of rest, the participants then engaged in a 30-trial isometric fatigue protocol during which maximal elbow flexion torque was measured with a load-cell, and the maximal rate of change in the torque (dtau/dt(max)) was obtained from the differentiated torque-time curve. Bipolar electrodes were used to monitor the SEMG spike activity of the biceps brachii. Mean spike amplitude (MSA) and mean spike frequency (MSF) were calculated for the torque development and constant-torque phases of the isometric contraction, termed Segment 1 and Segment 2, respectively. Mean power frequency (MPF) was also calculated for Segment 2. The five baseline contractions of the second and third sessions were compared with those of the first session and analyzed for training-related changes. Training increased dtau/dt(max) but failed to change maximal elbow flexion torque or MSA. However, there was an increase in the MSF during the torque development phase of the contraction (Segment 1). Both MSA and MSF were greatest during the constant-torque phase of the isometric contraction (Segment 2). There was a strong linear correlation (r=0.90, P<0.05) between MSF and MPF during (Segment 2). We hypothesize that the increase in dtau/dt(max) is due to enhanced motor-unit rate-coding. The demonstrated correlation between MSF and MPF measures will allow investigators to use spike analysis to examine the frequency content of the SEMG signal under non-stationary conditions.

Biomechanical Phenomena↗
PubMed1992

Clinical progress and quadriceps torque ratios during training of meniscectomy patients.

A prospective study of 21 patients after a meniscectomy is presented. During a standardized training program, consisting of static and dynamic exercises five times a week during 8 weeks, the following clinical signs were monitored: pain, swelling and limitation of the range of motion of the knee joint. Furthermore, isometric and isokinetic maximal torque of the knee extensors of both legs was determined in the patient group, as well as in a control group of healthy subjects (n = 11). We found that swelling of the knee joint seems to be the major cause of inhibition of muscle strength, resulting in low torque values in the initial phase of the training program. Mean maximal isometric torque of the operated knee increased from 151 Nm (SD = 50) to 282 Nm (SD = 50). Isokinetic mean maximal torque increased from 77 Nm (SD = 32) to 164 Nm (SD = 28). Isometric and isokinetic mean maximal torque of the nonoperated leg increased 15% and 10%, respectively. In the control group torque output of the knee extensors remained at about the same level. It appeared that the torque differences between both legs are more pronounced in the isokinetic tests than in the isometric tests. At the end of the training program isometric and isokinetic maximal torque of the knee extensors of the operated knee still showed a deficit of 12% and 21%, respectively. Isokinetic testing is more sensitive for small strength differences than isometric testing.

Exercise Therapy↗
PubMed1977

Maximum isometric knee flexor and extensor muscle contractions: normal patterns of torque versus time.

Isometric torque of the knee flexor and extensor muscles were recorded for 5 seconds at three knee joint positions. The subjects included healthy men in age groups from 20 to 35 and 45 to 65 years of age. The amplitudes and duration of peak torque and the time to peak torque were measured for each contraction. Peak torque was usually maintaned less than 0.1 second and never longer than 0.9 second. At each of the three angles, the mean extensor muscle torque was higher than the mean flexor muscle torque in both age groups, and the mean torque for both muscle group was higher among the younger than among the older man. The highest average torque was recorded at the knee angle of 60 degrees for the extensor muscles and 45 degrees for the flexor muscles, but this was not always a stereotyped response either for a given individual or among individuals.

Adult↗
PubMed1987

Effect of electrical stimulation current frequencies on isometric knee extension torque.

The purpose of this study was to compare the isometric knee extension torques of male and female subjects during maximal voluntary contractions (MVCs), electrical stimulation only, and electrical stimulation superimposed onto MVCs at electrical stimulation current frequencies of 20, 50, and 100 Hz. An asymmetrical, bidirectional, nonionizing waveform of 1-msec pulse duration was delivered through the femoral nerve and the superficial quadriceps femoris muscles at maximally tolerated intensity for each subject. The male subjects (n = 20) demonstrated significantly greater absolute torques under all contraction conditions than did the female subjects (n = 20) (p less than .01); when the torques were expressed as a percentage of each subject's MVC torque, however, no significant differences were observed between the sexes. Overall, the superimposed contractions at 50 and 100 Hz and the MVCs had similar torque values, all being significantly greater than the torque values produced by electrical stimulation only at frequencies of 20, 50, and 100 Hz and by the superimposed contractions at 20 Hz. Superimposing electrical stimulation onto MVCs did not result in greater torques than those produced by the MVCs alone. The three most effective contraction conditions, in terms of subject comfort (minimal discomfort) and increased torque, were the superimposed contractions at 50 and 100 Hz and MVCs alone, all of which involved a voluntary component.

Adolescent↗
PubMed1996

Force, torque, and stress relaxation with direct laryngoscopy.

The anesthetist exerts axial force on the laryngoscope handle to expose the glottis. The anesthetist must also apply a perpendicular force to balance the torque on the laryngoscope. Several studies have measured axial force during direct laryngoscopy, but none has measured torque. This study used a newly designed laryngoscope handle to measure force and torque simultaneously during direct laryngoscopy of ASA grade I and II patients requiring general anesthesia and endotracheal intubation for elective surgery. In 58 patients, peak force averaged 38 +/- 2 newtons. Peak torque averaged 4 +/- 0.2 newton-meters, and the perpendicular force was estimated as 40 +/- 2 newtons. The peak torque that can be balanced by the wrist is approximately 6 newton-meters, suggesting that torque may be a limiting factor for laryngoscopy in some situations. Peak force and torque demonstrated stress relaxation, a viscous property of biologic tissues. Force and torque decreased monoexponentially to approximately 70% of peak values with a half-time of 4 +/- 0.3 s. The phenomenon occurred in spite of administration of muscle relaxants, and was probably due to stress relaxation of pharyngeal tissues that are passively stretched during laryngoscopy.

Adult↗
PubMed1992

The influence of lordosis on axial trunk torque and trunk muscle myoelectric activity.

Force contributions from the facet complex and posterior ligaments during the generation of axial torque are a function of lordosis, and it has been speculated that these forces together with muscular contributions play a role in axial trunk twisting. This study investigated the electromyographic activity of the trunk musculature and torque-generating capacity of the lumbar spine under the conditions of normal lordosis, hyperlordosis, and hypolordosis. Eleven male subjects volunteered for this study. The subjects performed isometric twisting efforts and maximum dynamic twisting efforts at 30 degrees/sec. The myoelectric activity levels (normalized to maximal amplitude obtained from nontwist activities) were quite low despite maximal efforts to generate axial torque (for example: approximately 60% maximum voluntary contraction for latissimus dorsi and even lower for the abdominals). Furthermore, changes in lordosis did not produce any consistent changes in muscle activity, although a hyperlordotic spine produced significantly smaller axial torques, and a hypolordotic spine smaller still. Larger torques were measured during all three conditions of lordosis, as the subjects rotated toward an untwisted position, and lower torques as the subjects rotated away. The opposite trend was observed, however, in myoelectric activity of the agonistic side of latissimus dorsi, the thoracic level of erector spine, and the lumbar level of erector spinae, i.e., larger amplitudes were observed as the trunk was twisted away from the untwisted position. These data suggest that tissues other than muscle (i.e., passive tissue) contribute significantly to axial torque production and that the flexed and twisted spine is less able to resist applied axial torques, possibly increasing the risk of torsional injury.

Abdominal Muscles↗
PubMed1993

Pedicle screw pullout strength. Correlation with insertional torque.

This study was designed to correlate several parameters regarding pedicle screw bone/metal interface strength. The insertional torque measured during tapping and placement of pedicle screws was correlated with the bone mineral density of the vertebral body, the dimensions of the pedicle, the method of preparation of the pedicle, and the amount of load and number of cycles to failure of the bone/metal interface. Thirty human cadaveric lumbar vertebrae were instrumented with 6.5-mm pedicle screws. The maximum torque achieved during insertion was digitally recorded. A cyclic pedicle screw pullout test was performed. A linear correlation existed between both the insertional torque when tapping or when inserting a screw and the number of cycles to ultimate pedicle screw pullout. An inverse linear relationship was found between the pedicle width and cycles to failure. There was no linear correlation found when comparing the number of cycles to failure to bone mineral density. These findings suggest that insertional torque is a good predictor of bone-metal interface failure. Bone mineral density of the vertebral body was less effective as a predictor of failure. Smaller pedicle width correlated with increased insertional torque and cycles to failure. This may explain why patients with osteoporosis on radiography may still obtain stable fixation with pedicle screws. Other factors, such as pedicle dimensions and shape, affect screw purchase as much as vertebral body bone density. Insertional torque less than 4.0 inch-pounds led to early pedicle screw pullout. This study forms the basis for the authors' clinical use of an instrumented torque screwdriver to measure insertional torque in the operating room.

Aged↗
PubMed1993

Providing optimum torque to implant prostheses: a pilot study.

Ten N/cm torque has been proposed as the optimum level for the tightening of implant retaining gold screws in order to preload the implant components to limit loosening and fracture. The purpose of this study was to determine the influence of instrumentation and operator experience on the torque generated during manual tightening of slotted gold screws. Sixteen subjects, divided into four groups based on experience, were instructed to tighten five screws into implant analogs with 20-mm and 37-mm slotted screwdrivers. The screws were then removed with a torque gauge. All of the groups of subjects were able to generate significantly greater torque with the 37-mm screwdriver. Dentists with no implant treatment experience generated significantly less torque than the other three groups. Of the 12 dentist subjects, only 3 generated the optimal amount of torque when using the 20-mm screwdriver. Operators who had little experience dealing with implant prostheses were not able to provide the recommended torque and experienced operators tended to generate more than the recommended amount. None of the subjects were able to generate consistent torque values.

Analysis of Variance↗
PubMed1990

Effects of electrical stimulation on eccentric and concentric torque-velocity relationships during knee extension in man.

The purpose of this study was to examine the effects of electrical stimulation on torque output during knee extension. Nine well-trained males (19-43 years) performed maximal voluntary, electrically evoked and superimposed eccentric and concentric knee extensions at velocities of 60, 180 and 360 degrees s-1, plus an isometric test (torque was always recorded at a 60 degree knee angle). Fifty-hertz stimulation was applied percutaneously at the maximum tolerated voltage (140-200 V). By superimposing electrical stimulation, eccentric torque could be increased by an average of 21-24% above the voluntary level (P less than 0.05). No corresponding differences were observed between superimposed and voluntary torques under isometric or concentric conditions. Electrically evoked torque also exceeded voluntary torque under eccentric conditions (11-12%, P less than 0.05), but was less under isometric and concentric conditions (-10 to -52%, P less than 0.05). Within the limitations of the study, it was concluded that eccentric knee extension torque under maximal voluntary conditions does not represent the maximal torque-producing capacity. The action of a neural inhibitory mechanism was proposed as an explanation for this finding. If active, this mechanism may protect against the extreme muscle tension that could otherwise develop under truly maximal eccentric conditions.

Adult↗
PubMed2005

Gender comparisons of mechanomyographic amplitude and mean power frequency versus isometric torque relationships.

This study compared the patterns of mechanomyographic (MMG) amplitude and mean power frequency vs. torque relationships in men and women during isometric muscle actions of the biceps brachii. Seven men (mean age 23.9 +/- 3.5 yrs) and 8 women (mean 21.0 +/- 1.3 yrs) performed submaximal to maximal isometric muscle actions of the dominant forearm flexors. Following determination of the isometric maximum voluntary contraction (MVC), they randomly performed submaximal step muscle actions in 10% increments from 10% to 90% MVC. Polynomial regression analyses indicated that the MMG amplitude vs. isometric torque relationship for the men was best fit with a cubic model (R(2) = 0.983),,where MMG amplitude increased slightly from 10% to 20% MVC, increased rapidly from 20% to 80% MVC, and plateaued from 80% to 100% MVC. For the women, MMG amplitude increased linearly (r(2) = 0.949) from 10% to 100% MVC. Linear models also provided the best fit for the MMG mean power frequency vs. isometric torque relationship in both the men (r(2) = 0.813) and women (r(2) = 0.578). The results demonstrated gender differences in the MMG amplitude vs. isometric torque relationship, but similar torque-related patterns for MMG mean power frequency. These findings suggested that the plateau in MMG amplitude at high levels of isometric torque production for the biceps brachii in the men, but not the women, may have been due to greater isometric torque, muscle stiffness, and/or intramuscular fluid pressure in the men, rather than to differences in motor unit activation strategies for modulating isometric torque production.

Adult↗