Search

[Purpose] Changes in the muscle performance of professional motorized athletes using pycnogenol-containing supplements have not been clarified. The purpose of this study was to evaluate the changes in muscle strength and endurance of professional cyclists during 4 weeks of training with the use of PycnoRacerTM. [Participants and Methods] Eight professional cyclists were requested to consume PycnoRacerTM twice/day for 4 weeks. The muscle endurance test consisted of 50 consecutive knee flexion and extension exercises at 180°/sec using an isokinetic torque machine before and after PycnoRacerTM administration. The athletes' body composition, including leg muscle mass, was also measured. [Results] The maximum flexor muscle torque and 41st-50th flexion muscle torque values significantly improved after supplement consumption (average improvement of 8.5%; range, 13.3-67.2%). The leg muscle mass and body composition did not differ significantly between the two conditions. The participants showed an average improvement of 31.8% (range, 0.9-67.8%) in their total work with cycling training. No adverse events were observed. [Conclusion] The use of PycnoRacerTM may improve training, muscle strength, and endurance, but not muscle mass.

In sweep rowers, the lower extremities muscle strength translates into the driving force of the boat. Therefore, isokinetic assessment of muscle torque is used by coaches as an indicator of the level of athletes' preparation for competitions. A total of 22 elite sweep rowers performed an isokinetic test of knee joint flexors and extensors, and a test on an asymmetric ergometer with the electromyography measures. Significantly higher quadriceps peak torque was shown during the beginning than the end of the preparatory period (

The study aimed to analyse the effectiveness of two variants of 8-week strength training (hypertrophy, strength) with different modes of resistance. Healthy male subjects (n=75) were allocated to five groups of equal size: hypertrophy training with a variable cam (Hyp-Cam), hypertrophy training with disc plates (Hyp-Disc), maximal strength training with a variable cam (Str-Cam), maximal strength training with disc plates (Str-Disc), and a control group (CG). The Hyp-Cam and Str-Cam groups trained with a machine where the load was adjusted to the strength capabilities of the elbow flexors. The Hyp-Disc and Str-Disc groups trained on a separate machine in which a load was applied with disc plates. The CG did not train. All groups were assessed for changes and differences in one-repetition (1RM) lifts, isokinetic muscle torque, arm circumference and arm skinfold thickness, and plasma creatine kinase (CK) activity. Within the 8-week training period the 1RM increased (p.05) or Str-Disc (0.2 cm; p>.05) group. Skinfold thickness of the biceps and triceps decreased more within the 8-week period in Str-Cam (by 1.1 and 2.1 cm; p.05 and p.05 and p.05). The 8-week hypertrophy training with a variable cam results in greater peak muscle torque improvement than in the other examined protocols, with an insignificant increase in training-induced muscle damage indices.

Spinal cord injury (SCI) results in deleterious skeletal muscle adaptations, such as relevant atrophy and loss of force. In particular, the relevant loss of lower-limb force-generating capacity may limit functional mobility even if neuronal control was sufficient. Currently, methods of assessing maximal force-generating capacity using neuromuscular electrical stimulation (NMES) are limited in individuals who cannot tolerate higher stimulation amplitudes, such as those with residual sensation and those at risk of fracture. In this study, we examined the relationship between NMES amplitude and muscle torque exerted (recruitment curve) in order to determine whether maximal torque output can be characterized by a submaximal marker. Recruitment curves for knee extensors, knee flexors, and ankle plantarflexors were recorded from 30 individuals with motor complete SCI. NMES was delivered starting with an amplitude of 5 mA, and increasing by 5 mA for every subsequent stimulation until either the participant requested to stop the stimulation or the maximum stimulation amplitude (140 mA) was reached. Significant correlations between peak slope of the recruitment curve and peak torque for all muscle groups were found (knee extensors, r = 0.75; p 0.0001; knee flexors, r = 0.68; p 0.0001; ankle plantarflexors, r = 0.91; p 0.0001), indicating that muscles that show greater peak slope of the recruitment curve tend to generate a greater peak torque. This suggests that peak slope, which was achieved at an average stimulation intensity (55.0 mA) that was 43% smaller than that corresponding to peak torque (97.4 mA), may be used as a submaximal marker for characterizing maximal torque output in individuals with SCI.

The primary objective was to compare hip and knee isometric muscle strength between individuals with a first-time acute lateral ankle sprain and controls. A secondary objective was to investigate hip and knee isometric muscle strength three months post-injury.Cross-sectional and prospective follow-up components.Laboratory environment.Forty-two participants (21 acute lateral ankle sprain and 21 controls) matched for age, sex, physical activity and leg dominance participated.Hip and knee isometric muscle torque was assessed using a rigidly fixated hand-held dynamometer. Testing in acute lateral ankle sprain participants was performed within four weeks of injury and three months post-injury. Controls were tested at one timepoint.There were no differences in hip or knee isometric muscle torque between acute lateral ankle sprain and control participants (mean differences0.08). Hip and knee isometric muscle torque in acute ankle sprain participants did not differ between baseline and three months post-injury testing (mean difference0.06).Proximal lower limb isometric strength is not impaired within the first three months of sustaining a first-time lateral ankle sprain injury. This implies that hip and knee isometric strength deficits in individuals with CAI may occur at some later stage.

Purpose: This study aimed to determine the contribution of metabolic, cardiopulmonary, neuromuscular, and biomechanical factors to the energy cost (ECR) of graded running in well-trained runners. Methods: Eight men who were well-trained trail runners (age: 29 [10] y, mean [SD]; maximum oxygen consumption: 68.0 [6.4] mL·min−1·kg−1) completed maximal isometric evaluations of lower limb extensor muscles and 3 randomized trials on a treadmill to determine their metabolic and cardiovascular responses and running gait kinematics during downhill (DR: −15% slope), level (0%), and uphill running (UR: 15%) performed at similar O2 uptake (approximately 60% maximum oxygen consumption). Results: Despite similar O2 demand, ECR was lower in DR versus level running versus UR (2.5 [0.2] vs 3.6 [0.2] vs 7.9 [0.5] J·kg−1·m−1, respectively; all P r2 = .63; P = .018). Importantly, while ECR was correlated with heart rate, cardiac output, and arteriovenous O2 difference in UR (all r2 > .50; P r2 > .58; P Conclusion: The determining physiological factors of ECR might be slope specific, mainly metabolic and cardiovascular in UR versus mainly neuromuscular and mechanical in DR. This possible slope specificity of ECR during incline running opens the way for the implementation of differentiated physiological evaluations and training strategies to optimize performance in well-trained trail runners.

This study explores the cardiorespiratory and muscular fatigue responses to downhill (DR) vs uphill running (UR) at similar running speed or similar oxygen uptake (⩒O2). Eight well-trained, male, t...

Objectives We compared hip and knee isometric muscle torque between individuals with chronic ankle instability (CAI), those who have sustained one ankle sprain with no ongoing problems (copers) and healthy controls. Our secondary objective was to compare balance between groups and investigate the relationship between muscle torque and balance. Design Cross-sectional study. Methods 22 CAI, 20 copers and 22 uninjured participants were tested. Isometric torque (normalised to body mass (Nm/kg)) was measured using a rigidly-fixated hand-held dynamometer. Balance was assessed with the Y-balance test. Results Knee and hip flexor and extensor, and hip adductor and abductor muscle torque was less in individuals with CAI compared to controls (standardised mean difference (SMD) >1.2). Hip and knee flexor and extensor muscle torque was less in CAI participants than copers (SMD: 0.69–1.1). Hip external and internal rotator torque did not differ between groups. There was no difference in hip or knee muscle torque between controls and copers (SMD: 0.01–0. 54). Balance was impaired in CAI participants compared to copers and controls in all directions. There was a strong positive correlation between posterolateral Y-balance test performance and torque of the hip adductors (r = 0.53), flexors (r = 0.52) and extensors (r = 0.50). Conclusions Individuals with CAI have weak knee and hip muscles compared to copers and controls. Hip strength was shown to be related to posterolateral balance performance. Future studies may investigate the effect of hip and knee strengthening exercise on ongoing ankle problems, such as episodic giving way in individuals with CAI.

Instrument-assisted soft tissue mobilization (IASTM) is a new technique that has been known to be effective in reducing muscle tightness in athletics. However, little is known about its effect on the range of motion, muscle power, and torque compared to manual stretching among non-athletics. Thus, the study was aimed to compare the effectiveness between IASTM and manual stretching in improving hip flexion active range of motion (ROM), muscle torque and power on hamstring muscle complex (HMC) tightness in one session.Twenty-three young male college students with unilateral hamstring tightness measured via straight leg raising (SLR) test (65°) were randomly assigned to one of two groups. Twelve participants received the application of IASTM (group 1), and eleven received manual stretching (group 2). Hip flexion active ROM was measured via goniometer, the torquepower of the hamstring muscle were measured using Humac isokinetic dynamometer, before and after both interventions. (ISRCTN17693345).There was no significant difference in the improvement of hip flexion active ROM (69.6 ± 6.6 vs 72.5 ± 7.9, p = .34), HMC torque (63.7 ± 14.5 vs 53.2 ± 16.3, p = .14), and HMC power (47.8 ± 11.8 vs 40.9 ± 16.3, p = .34) between group 1 and group 2 respectively. When a comparison was made within each group, significant improvements in hip active flexion ROM was found in both groups (p's .001), and HMC power was significantly improved in group 1 (p = .04) but not in group 2.The current study findings demonstrate that IASTM was as effective as manual stretching in improving hip flexion active ROM, muscle torque and power among non-athletic people with HMC tightness.

Bioelectrical impedance spectroscopy (BIS) can assess intracellular water (ICW) and total water (TW) in limbs. This study aimed to examine whether BIS can explain a part of the inter-individual variation of the muscle size-strength relationship in older adults. We analyzed the data of 79 participants aged 64-86 years. The maximal voluntary isometric torques of dorsiflexion and plantar flexion on the right side were measured. The anterior and posterior muscle thickness (MT) in the right lower leg was assessed using ultrasonography. The length of the right lower leg (L) was measured, and the ICW-to-TW ratio (ICW/TW) in the right lower leg was obtained using BIS. The MT was multiplied by L to represent an index of muscle volume (MV). Correlation and stepwise regression analyses were performed. The anterior and posterior MT × L significantly and positively correlated with the muscle torque of dorsiflexion and plantar flexion (r = 0.710 and 0.649, respectively, P 0.001). In the stepwise regression analyses, ICW/TW was selected as a significant predictor of muscle torque independent of MT × L (P 0.05) for both dorsiflexion and plantar flexion. Electrical parameters of BIS (membrane capacitance, characteristics frequency, and phase angle) in the lower leg also significantly correlated with muscle torques. In addition, the skeletal muscle mass index (appendicular lean mass/height

Study Design A controlled laboratory study, with a single-blind, block-randomization crossover design. Objectives To compare the electrically elicited knee extensor torque produced by 3 clinically available waveforms: 2500-Hz burst-modulated alternating current (BMAC), 1000-Hz BMAC, and 1000-Hz burst-modulated biphasic square-wave pulsed current (BMBPC). Background Neuromuscular electrical stimulation (NMES) is the therapeutic use of electrical current to strengthen muscle. Muscle torque produced by NMES is limited by discomfort. Methods The knee extensor maximal volitional isometric torque (KEMVIT) of 33 able-bodied participants (18 female) was measured and used to normalize the electrically elicited knee extensor torque to produce a percent of KEMVIT (%KEMVIT). Electrically elicited isometric knee extensor torque was measured in response to each of the waveforms at the participants' maximum tolerance. Results The average maximum tolerated stimulation produced 32.0 ± 16.7 %KEMVIT with 2500-Hz BMAC, 38.2 ± 18.4 %KEMVIT with 1000-Hz BMAC, and 42.2 ± 17.1 %KEMVIT with 1000-Hz BMBPC. Tukey honest significant difference (HSD) post hoc testing revealed a statistically significant difference between 2500-Hz BMAC and 1000-Hz BMAC (P = .046), and between 2500-Hz BMAC and 1000-Hz BMBPC (P.001). No statistically significant difference was found between 1000-Hz BMAC and 1000-Hz BMBPC (P = .267). Conclusion For eliciting maximum knee extensor muscle torque, 1000-Hz BMBPC and 1000-Hz BMAC were similarly effective, and 2500-Hz BMAC was less effective. J Orthop Sports Phys Ther 2018;48(3):217-224. Epub 19 Dec 2017. doi:10.2519/jospt.2018.7601.

Introduction . The aim of the study was to determine the changes in the peak torque of the knee extensors and flexors of the dominant lower limb, the shoulder internal and external rotators of the dominant upper limb, and the shoulder extensors and flexors of the dominant upper limb as well as the changes in jump height in volleyball players during the annual training macrocycle. Material and methods . The study involved 13 volleyball players from a Polish second-league team. The measurements were performed five times: before the preparation period (T1), at the beginning of the competitive season (T2), in the middle (T3) and at the end of the first competition period (T4), and after the competitive season (T5). The torque of the knee muscles and shoulder rotators was measured in isokinetic conditions, and the torque of the shoulder extensors and flexors was assessed in isometric conditions. Jumping ability was tested using a piezoelectric platform. Results . We observed statistically significant differences (p < 0.05) in jump height and relative peak torque between the measurements, except for the torque of the shoulder external rotators and flexors. The results of multiple factor analysis based on 5 sets composed of 5 strength variables revealed differences between subjects and measurement sessions. Conclusions . The results obtained indicate that strength and jumping ability should be assessed regularly during the competitive season. The findings of the study suggest that it is necessary to modify the training methods used during the preparation period and individualize the training in the final phase of the competition period.

Introduction Kinesio taping consists of the attachment of a thin elastic tape over specific muscles, the thickness of which is similar to that of the epidermis. Objective The aim of the present study was to compare the effect of Kinesio taping and placebo taping on muscle torque, muscle activity and jumping performance soccer players. Methods Thirty athletes were randomly allocated to two groups (Group A: Kinesio taping and Group B: placebo taping). The participants were instructed to perform the Hop test's and were submitted to an isokinetic evaluation of the knee extensors as well as an electromyographic evaluation of the retus femoris muscle of the dominant lower limb. Next, Kinesio taping was performed for the activation of the rectus femoris muscle in Group A and placebo taping was performed in Group B. The participants were reevaluated 30 minutes after taping and 24 hours after the first evaluation using the same tests. Intra-group and inter-group comparisons were made considering the three evaluation times. Results No statistically significant differences were found between groups at any evaluation time regarding the Hop test's, root mean square of the electromyographic signal or peak torque of the knee extensors of the dominant lower limb (p>0.05). Conclusion Kinesio taping for the activation of the rectus femoris muscle has no effect on peak muscle torque, muscle activity or jumping performance among soccer players.

International audience; Purpose: Perception of action capabilities can be altered by changes in sensorimotor processes, as showed in previous works in populations dealing with regular and pathological sensorimotor deficits. Misestimating changes in performance ability could lead to risky behavior, injury, and/or reduced performance. However, the relationship between sensorimotor processes, the action-perception coupling, and the related anatomical structures is still a matter of debate. We investigated whether changes in the muscle-tendon system's mechanical properties experimentally induced by eccentric contractions could alter the action-perception coupling (APC) in a reaching-to-grasp task, in which the participants estimated the maximal distance they predicted that they would able to reach a glass.Methods: Based on their repartition, volunteers performed a conditioning session the first day: a series of isokinetic elbow extension in passive condition (control group, n = 11) or when performing elbow flexors eccentric contractions (eccentric group, n = 11). Performance estimates and actual performances in a reaching-to-grasp task were completed before, and immediately, 24 hours and 48 hours after the conditioning session. Alterations of musculo-articular mechanical properties were assessed through global joint stiffness (joint passive torque through load/unload cycles) and local stiffness (muscle elastography).Results: The results showed that the APC related to reaching-to-grasp performance was not impacted by post-exercise changes in mechanical properties of the musculo-articular system.Conclusion: These findings emphasize the central dimension of sensorimotor processing instead of peripheral structures to investigate the APC for an altered sensorimotor environment.

Background Therapeutic management of the upper extremity (UE) function of people with spinal muscular atrophy (SMA) requires sensitive and objective assessment. Therefore, we aimed to measure physiologic UE function of SMA patients with different functional abilities and evaluate the relation between these physiologic measures and functional UE scales. Methods 12 male and 5 female SMA patients (mean age 42 years; range 6–62 years) participated in this explorative study. Concerning the physiologic level, the maximal muscle torque, the maximal and normalized surface electromyography (sEMG) amplitudes, and the maximal passive and active joint angles were measured. Concerning the activity level, the Performance of the Upper Limb (PUL) scale was used, and hand function was examined using the Nine-Hole Peg Test and the Timed Test of In-Hand Manipulation (TIHM). Results Outcome measures that significantly related to the functional ability were: the PUL score (all dimensions); the finger to palm task of the Timed TIHM; biceps, triceps, and forearm extensor strength; and the active range of motion of shoulder abduction, shoulder flexion, and wrist extension. In addition, the following physiologic variables were related to the activity level (PUL score): hand function (the Nine-Hole Peg Test; Rs = − 0.61), the Timed TIHM (Rs = − 0.53), the maximal muscle torque (Rs = 0.74), the maximal sEMG amplitude (Rs = 0.79), and the maximal active joint angle (Rs = 0.88). Conclusions Muscle functions in SMA patients are already affected before activity limitations are noticeable. Consequently, monitoring the maximal muscle strength and the normalized muscle activity during task performance could play a role in the early detection of UE limitations. The mechanism behind the loss of arm activities due to SMA is primarily caused by decreasing muscle capacity, which influences the ability to move an arm actively. In clinical practices, these dimensions should be considered separately when monitoring disease progression in order to better evaluate the need for interventions.

The link between age-related changes in muscle strength and gait is unclear. We tested if knee extensor functional demand differs by age and physical activity status and if functional demand increases with walking speed or after exercise. Gait and knee extensor muscle torque were collected from young adults and highly and less active older adults before and after treadmill walking. Functional demand was the ratio of knee moments during gait to knee extensor muscle torques estimated from participant-specific torque–velocity curves. Functional demand at the peak knee flexion moment was greater in less active older adults than young adults (29.3% [14.3%] vs 24.6% [12.1%]) and increased with walking speed (32.0% [13.9%] vs 22.8% [10.4%]). Functional demand at both knee extension moments increased ∼2% to 3% after exercise. The low functional demand found in this study suggests that healthy adults maintain a reserve of knee extensor strength.

Objectives: Determine the effects of varying frequency, phase duration, and interphase interval (IPI) of symmetrical, biphasic pulsed current (SBPC) on quadriceps femoris muscle torque production, ...

Background Many studies have investigated the correlation between muscle torque and joint position sense (JPS), but few studies have been performed on the correlation between torque ratio and JPS. Objective The aim of this study was to investigate JPS and muscle torque ratios of agonist and antagonist muscles in the ankle and knee joints of young adults. Methods A total of 38 right handed healthy participants, 12 males and 26 females, were recruited. All participants measured their peak torque of knee flexor/extensor and ankle dorsiflexor/plantar flexor by using a Biodex system. They also used the Biodex to assess the proprioception through active joint reposition sense test in knee and ankle joint. Peak torque of each muscle, agonist/antagonist torque ratio and JPS error were collected, and Pearson's correlation analysis was used to examine correlations between peak torque, torque ratio and JPS error. Results For knee joints, correlations were found between flexion and extension torque, extension torque and torque ratio, and torque ratio and JPS error (r= 0.825/p= 0.000, r=-0.482/p= 0.002, and r=-0.685/p= 0.000, respectively). For ankle joints, correlations were found between dorsiflexion and plantar flexion torques, plantar flexion torque and torque ratio, plantar flexion torque and JPS, and torque ratio and JPS (r= 0.654/p= 0.000, r=-0.621/p= 0.000, r=-0.563/p= 0.000, and r=-0.761/p= 0.000, respectively). Conclusions JPS error of lower extremity joint may be more related with agonist/antagonist torque ratio rather than peak torque. Therefore, people who will have training for reducing JPS error need to consider torque ratio, too.

The aim of this study was to evaluate the effect of long-term running training on muscle strength of men aged 50 and above. The study involved two groups of men aged 50 and above: physically active (E, n = 34) and inactive (NE, n = 20). Body composition was assessed with the electrical bioimpedance method. The isometric maximum voluntary contraction (MVC) was the main measurement. The value of muscle torque achieved by a group of synergists (operating in the given joint) during a short isometric contraction was evaluated. Ten groups of flexor and extensor muscles of the elbow, shoulder, hip, knee, and torso joints were measured. In addition, a 3 s measurement of grip strength of the right (F r ) and left (F l ) hand was taken using a hand dynamometer. The obtained values enabled to calculate the symmetry index (SI). Men who had been running regularly were characterized by a significantly lower strength level ( p < .05). Results in the NE group were determined to a great extent by significantly different body weights ( p < .001) and a significantly higher body fat mass (FAT) content ( p < .001). SI was statistically higher in the reference group ( p < .05). Long-distance run training reduces FAT while maintaining a high level of muscle strength. These studies indirectly confirm the effect of strengthening slow-twitch motor units in men aged 50 (Doherty & Brown 1993; Kanda & Hashizume 1989). In addition, stimulating the body through physical effort helps it also to maintain a high level of strength symmetry, which is a preventive factor in reducing the number of injuries.

Older females experience higher rates of disability than males, potentially due to sex-specific differences in gait and muscle function. The authors evaluated the effects of age and physical activity (PA) on gait mechanics and knee extensor muscle function in males and females. Three groups of 20 individuals (each 10 females) participated: young (21–35 y) and highly and less active older (55–70 y) adults. Knee extensor strength and joint mechanics during preferred speed gait were collected before and after 30 minutes of walking. Age by sex and PA by sex interactions indicated older and less active older females had lower concentric knee extensor muscle power and larger hip extension moments than males. After 30 minutes of walking, older less active adults had larger decreases in knee extensor power than their highly active older counterparts, and older adults of both sexes had decreases in ankle dorsiflexion moments while young adults did not. These results suggest that older, particularly less active, adults are susceptible to knee extensor muscle fatigue from moderate activity. For older adults, high levels of PA may be necessary to preserve gait mechanics in response to a bout of exercise. This new information may be important for targeting interventions in at-risk older adults.

Background:Long-term maintenance of sports participation is important for young men undergoing anterior cruciate ligament (ACL) reconstruction. Identifying biomechanical characteristics in patients who achieve this goal can assist in elaborating rehabilitation programs and in identifying successful recovery, but this has rarely been investigated.Purpose:To test the association between maintenance of sports participation at 5 to 10 years after ACL reconstruction and measures of force production and landing biomechanics in men.Study Design:Cross-sectional study; Level of evidence, 3.Methods:A total of 30 men who underwent isolated ACL reconstruction were examined. At 5- to 10-year follow-up, associations were tested between reported outcomes of sports maintenance and objective biomechanical measures. The biomechanical tests included isokinetic knee torque and lower limb kinetics and kinematics during landing tasks. Measurements for each limb were conducted separately, and side-to-side symmetry indices (SI) were calculated. Subgroups included SI greater than +10% (ie, extreme positive), SI lower than –10% (ie, extreme negative), and SI between –10% and +10% (ie, symmetric).Results:At follow-up, concentric knee torque in the operated limb correlated with Tegner and Marx scores ( r = 0.42-0.47; P ≤ .05). Regarding the SI of knee torque, the highest Tegner, Marx, and KOOS (Knee injury and Osteoarthritis Outcome Score) results were associated with symmetry, as opposed to patients with extreme positive or extreme negative SIs ( P < .05). As for landing kinematics, Tegner score negatively correlated with knee range of motion (ROM) in the operated limb ( r = –0.38; P ≤ .05). With regard to SI, hip and knee ROM correlated with Tegner, IKDC, and KOOS scores ( r = 0.41-0.51; P ≤ .05). Specifically, the highest sports participation levels were associated with achieving symmetric hip and knee ROM but also with extreme positive SIs, as opposed to patients with extreme negative SIs ( P < .03), indicating substantially higher ROM in the uninjured limb as compared with the operated limb.Conclusion:At 5 to 10 years after ACL reconstruction, maintenance of sports participation was associated with symmetric side-to-side concentric knee torque and with producing greater attenuation of hip and knee ROM during the drop jump landing in the operated limb. Therefore, eccentric load programs that can improve attenuation-phase kinematics during landing tasks may be valuable in addition to concentric training and may facilitate enhanced long-term outcomes.

Research background and hypothesis. There is much research information about the relationship between the knee joint angle and the quadriceps muscle torque (Mohamed et al., 2002), but still we lack evidence about the relationship between ankle angle and calf muscle torque. Research aim. The purpose of this research was to establish the dependence of maximal voluntary contraction (MVC) and electrical stimulation (ES)-evoked torque and calf muscle electrical activity (EMG) on different ankle plantar and dorsal fl exion angles. We hypothesized that the calf muscle MVC and ES-evoked torque as well as muscle EMG amplitude would increase with increasing muscle length (i. . increasing ankle angle). Research methods. The subjects in the research were ten non-trained men. Calf plantar and dorsal fl exors muscle ES and MVC torque were tested at eight different ankle angles (–25 o ; –15 o ; –5 o ; 0 o ; 15 o ; 25 o ; 35 o ; 45 o ) which were chosen in randomized sequence. The tibialis anterior, soleus, gastrocnemius lateralis and medialis muscle EMG were measured during muscle MVC. Research results. The results showed that the highest ES-evoked and MVC developed torque of plantar fl exion muscles was at –25° ankle angle (149.1 ± 31.6 N·m and 207.8 ± 38.1 N·m, respectively), while the highest dorsal fl exion MVC muscle torque was at 25° ankle angle (47.2 ± 8.1 N·m). However, dorsal fl exion muscle MVC torque increased with the muscle length only until 25° ankle angle. Discussion and conclusions. Plantar flexion muscle electrical stimulation evoked and plantar / dorsal fl exion muscle maximal voluntary contraction torques are highest at that ankle angle where muscle length is the longest. Keywords: maximal voluntary contraction, electrical stimulation, EMG.

The torque-sharing strategies between synergistic muscles may have important functional consequences. This study involved two experiments. The first experiment ( n = 22) aimed 1) to determine the relationship between the distribution of activation and the distribution of torque-generating capacity among the heads of the hamstring, and 2) to describe individual torque-sharing strategies and to determine whether these strategies are similar between legs. The second experiment ( n = 35) aimed to determine whether the distribution of activation between the muscle heads affects endurance performance during a sustained submaximal knee flexion task. Surface electromyography (EMG) was recorded from biceps femoris (BF), semimembranosus (SM), and semitendinosus (ST) during submaximal isometric knee flexions. Torque-generating capacity was estimated by measuring muscle volume, fascicle length, pennation angle, and moment arm. The product of the normalized EMG amplitude and the torque-generating capacity was used as an index of muscle torque. The distributions of muscle activation and of torque-generating capacity were not correlated significantly (all P > 0.18). Thus, there was a torque imbalance between the muscle heads (ST torque > BF and SM torque; P < 0.001), the magnitude of which varied greatly between participants. A significant negative correlation was observed between the imbalance of activation across the hamstring muscles and the time to exhaustion ( P < 0.001); i.e., the larger the imbalance of activation across muscles, the lower the muscle endurance performance. Torque-sharing strategies between the heads of the hamstrings are individual specific and related to muscle endurance performance. Whether these individual strategies play a role in hamstring injury remains to be determined. NEW & NOTEWORTHY The distribution of activation among the heads of the hamstring is not related to the distribution of torque-generating capacity. The torque-sharing strategies within hamstring muscles vary greatly between individuals but are similar between legs. Hamstring coordination affects endurance performance; i.e., the larger the imbalance of activation across the muscle heads, the lower the muscle endurance.

OBJECTIVE: After spinal cord injury (SCI), hybrid stimulation patterns that interpose paired-pulse doublets over a constant-frequency background may enhance the metabolic “work” (muscle torque) performed by paralyzed muscle. This study examined the effect of background stimulation frequency on the torque contribution of the doublet before and after fatigue. DESIGN: Cross-sectional study. SETTING: Research laboratory in an academic medical center. PARTICIPANTS: Five men with chronic sensory and motor-complete SCI and ten non-SCI controls (6 males, 4 females). SCI subjects were recruited from a long-term study of unilateral plantar-flexor training; both limbs were tested for the present study. INTERVENTIONS: Subjects underwent plantar flexor stimulation at 5, 7, 9, and 12 Hz. The four background frequencies were overlaid with 6 ms doublets delivered at the start, middle, or at both the start and middle of each train. The 5 Hz and 12 Hz frequencies were analyzed after fatigue. OUTCOME MEASURES: Mean torque, peak torque, torque fusion index, doublet torque. RESULTS: Trains with doublets at both the start and middle yielded the most consistent enhancement of torque (all P

Introduction: In this investigation we aimed to deter- mine whether: (1) physical activity protects rat skeletal muscle from ischemia/reperfusion (I/R) injury; and (2) continued activity after I/R improves the rate of healing. Methods: Rats were divided into sedentary or active (voluntary wheel running) groups. Active rats ran for 4 weeks before I/R or 4 weeks before plus 4 weeks after I/R. Results: Activity before I/R resulted in 73.2% less mus- cle damage (Evans blue dye inclusion). Sedentary and active rats had a similar decline in neural-evoked (� 99%) and directly stimulated (� 70%) in vivo muscle torque, and a similar reduction in junctophilin 1. Active rats produced 19% and 15% greater neural-evoked torque compared with sedentary rats at 14 and 28 days postinjury, respectively, although the rate of recovery appeared similar. Conclusions: Activity protects against long- term muscle damage, but not short-term neural injury or excita- tion-contraction uncoupling. Continued activity neither acceler- ates nor hinders the rate of functional recovery. Muscle Nerve 52: 640-648, 2015 Extremity injuries are highly prevalent in both mili- tary 1 and civilian 2 trauma, and they often involve skeletal muscle. 3 In many cases, prolonged blood flow disruption due to concomitant vascular dam- age and/or acute compartment syndrome induces tissue ischemia, and subsequent surgical repair pro- motes reperfusion of the tissue. 4 Tissue reperfusion is necessary for limb salvage, although free radicals generated during this process further injure vascu- lar, neural, and muscular structures (i.e., ischemia/ reperfusion (I/R) injury 5-7 ). The underlying molec- ular mechanisms of I/R injury are fairly well under- stood, and a number of protective agents 8-10 and

The aim of this study is to compare values of force-velocity and functional walking capacity in elderly patients with intermittent claudication with respect to the control group.The study involved 135 individuals: 85-peripheral arterial disease (PAD) group diagnosed with stage II chronic lower limb ischemia, according to Fontaine's classification, and 50-control group. The studies included an assessment of walking capacity using a six-minute walk test (6MWT) and measurement of force-velocity parameters (peak torque-PTQ, total work-TW, average power-AVGP) of the lower limbs obtained by means of a functional dynamometry under isokinetic conditions.The peripheral arterial disease group is characterized by significantly lower values of force-velocity parameters compared to the control group (p0.005). Walking capacity in this group is significantly reduced due to significant differences in the distance covered (p0.0001), walking speed (p0.01), and its intensity (p0.01). Further, a positive correlation was found between the maximum distance specified in the six-minute walk test and lower limb muscle strength in the isokinetic test.Mean values of all force-velocity parameters and walk distance were significantly higher in the control group than in the peripheral arterial disease group. In the PAD group, in both men and women, the value of the agonist/antagonist ratio of both lower limbs are lower in men and women comparing to the control group. A rehabilitation program for patients with intermittent claudication must consider exercises improving strength, exercise capacity, and endurance in patients with PAD.

WOS: 000446805000006 PubMed ID: 25960982 After anterior cruciate ligament (ACL) reconstruction, which muscle groups are more affected from frequently developing thigh muscle atrophy is a matter of debate. We evaluate the effect of thigh circumference difference between patients' knees who were administered the ACL reconstruction with hamstring tendon autograft and intact knees, on torque between the hamstring and quadriceps muscles. Fifty-five patients at least 6 months follow-up period available were included in our study. Power measurements of quadriceps and hamstring muscle groups in patients' extremities were done by using isokinetic dynamometer. The maximum torque values at 60 degrees/sec, 240 degrees/sec in frequency, positions of flexion and extension were determined. In accordance with our findings it is still possible to encounter the thigh atrophy in average 28 months after ACL reconstruction surgery even under physical rehabilitation programs and appropriate follow-up. It is inevitable for the clinician to consider these changes in diagnosis and rehabilitation stages. It can't be ignored that muscle weakness mechanisms developing in the thigh circumference vary according to the thigh muscle group and knee flexors play an important role in thigh atrophy when determining an appropriate rehabilitation program after reconstruction application.

The aim of this study was to perform a comparative analysis of maximal muscle torques at individual stages of development of athletes and to determine the relationship between muscle torques, fighting methods and the level of sports performance. The activity of 25 judo contestants during judo combats and the effectiveness of actions were evaluated. Maximum muscle torques in flexors/extensors of the body trunk, shoulder, elbow, hip and knee joints were measured. The level of significance was set at p≤0.05; for multiple comparisons the Mann-Whitney U test, p≤0.016, was used. Intergroup differences in relative torques in five muscle groups studied (elbow extensors, shoulder flexors, knee flexors, knee extensors, hip flexors) were not significant. In cadets, relative maximum muscle torques in hip extensors correlated with the activity index (Spearman's r=0.756). In juniors, maximum relative torques in elbow flexors and knee flexors correlated with the activity index (r=0.73 and r=0.76, respectively). The effectiveness of actions correlated with relative maximum torque in elbow extensors (r=0.67). In seniors, the relative maximum muscle torque in shoulder flexors correlated with the activity index during the second part of the combat (r=0.821).

[Purpose] The purpose of this study was to clarify the influence of static stretching at warm-up on the isokinetic muscle torque (at 60°/sec) and muscle power (at 180°/sec) of the flexor muscle and extensor muscle of the knee joint. [Subjects and Methods] The subjects of this study were 10 healthy students with no medically specific findings. The warm-up group and warm-up with stretching group performed their respective warm-up prior to the isokinetic muscle torque evaluation of the knee joint. One-way ANOVA was performed by randomized block design for each variable. [Results] The results were as follows: First, the flexor peak torque and extensor peak torque of the knee joint tended to decrease at 60°/sec in the warm-up with stretching group compared with the control group and warm-up group, but without statistical significance. Second, extensor power at 180°/sec was also not statistically significant. However, it was found that flexor power increased significantly in the warm-up with stretching group at 180°/sec compared with the control group and warm-up group in which stretching was not performed. [Conclusion] Therefore, it is considered that in healthy adults, warm-up including two sets of stretching for 20 seconds per muscle group does not decrease muscle strength and muscle power.

The temporal structure, or complexity, of muscle torque output decreases with neuromuscular fatigue. The role of central fatigue in this process is unclear.We tested the hypothesis that caffeine administration would attenuate the fatigue-induced loss of torque complexity.Eleven healthy participants performed intermittent isometric contractions of the knee extensors to task failure at a target torque of 50% maximal voluntary contraction, with a 60% duty factor (6-s contraction, 4-s rest), 60 min after ingesting 6 mg·kg caffeine or a placebo. Torque and surface EMG signals were sampled continuously. Complexity and fractal scaling of torque were quantified using approximate entropy (ApEn) and the detrended fluctuation analysis (DFA) α scaling exponent. Global, central, and peripheral fatigue was quantified using maximal voluntary contractions with femoral nerve stimulation.Caffeine ingestion increased endurance by 30% ± 16% (mean ± SD; P = 0.019). Complexity decreased in both trials (decreased ApEn, increased DFA α; both P0.01), as global, central, and peripheral fatigue developed (all P0.01). Complexity decreased significantly more slowly after caffeine ingestion (ApEn, -0.04 ± 0.02 vs -0.06 ± 0.01 (P = 0.004); DFA α, 0.03 ± 0.02 vs 0.04 ± 0.03 (P = 0.024)), as did the rates of global (-18.2 ± 14.1 vs -23.0 ± 17.4 N·m·min, P = 0.004) and central (-3.5 ± 3.4 vs -5.7 ± 3.9 %·min, P = 0.02) but not peripheral (-6.1 ± 4.1 vs -7.9 ± 6.3 N·m·min, P = 0.06) fatigue.Caffeine ingestion slowed the fatigue-induced loss of torque complexity and increased the time to task failure during intermittent isometric contractions, most likely through central mechanisms.

Background: Many therapeutic uses for Pulsed magnetic fields have been extensively studied. Beneficial effects on the musculoskeletal system were established including bone healing, pain relief, and inflammatory conditions. The study aimed at investigating the possible effects of the pulsed magnetic field on quadriceps muscle torque, hamstring muscle torque and knee proprioception accuracy in athletic subjects. Methods: A randomized controlled trial which was carried out at the Faculty of Medical Rehabilitation Sciences, Taibah University, Saudi Arabia. Thirty healthy male athletic subjects, aging from 18 – 24 years were divided into two groups, study group (15 subjects) & control group (15 subjects). The pulsed magnetic field was applied for subjects of intervention group, while control group participants received sham pulsed magnetic field for 12 sessions over a period of 4 weeks. Quadriceps muscle torque, hamstring muscle torque & knee proprioception accuracy were measured before & after treatment for all participants using Biodex system 4 pro isokinetic dynamometer. Results: Multiway ANOVA was carried out to detect any significant differences within and between groups. Statistically significant differences between study and control groups were found after pulsed magnetic field application in quadriceps peak torque (at 60 and 120deg/sec) & hamstring peak torque (at 60 and 120deg/sec) and in knee proprioception accuracy (p-value was 0.004, 0.0001, 0.02, 0.03, 0.0001 respectively). Conclusion: Pulsed magnetic field has beneficial effects on quadriceps muscle peak torque, hamstring muscle peak torque and knee proprioception accuracy in healthy athletic subjects and can be advised as an adjunctive tool in rehabilitation programs.

Many studies have shown that unilateral transfemoral amputation involves asymmetric gait. Transfemoral amputation leads to muscle atrophy in a tight stump resulting in asymmetry in muscle torque between the amputated and intact limb. This research is aimed at verifying if a relationship between torque values of hip joint flexors and extensors and gait asymmetry in patients with TFA exists. Fourteen adult subjects with unilateral TFA took part in the experiment. Gait symmetry was evaluated based on the ground reaction force (GRF). Measurements of muscle torque of hip flexors and extensors were taken with a Biodex System. All measurements were taken under isokinetic (60°/s and 120°/s) and isometric conditions. The symmetry index of vertical GRF components was from 7.5 to 11.5%, and anterio-posterior GRF from 6.2 to 9.3%. The symmetry index for muscle torque was from 24.3 to 44% for flexors, from 39 to 50.5% for extensors, and from 28.6 to 50% in the flexor/extensor ratio. Gait asymmetry correlated with muscle torque in hip joint extensors. Therapy which enhances muscle torque may be an effective form of patient therapy. The patient needs to undergo evaluation of their muscle strength and have the therapy programme adjusted to their level of muscle torque deficit.

Background: Gait speed declines with increasing age, but it is unclear if gait speed preferentially correlates with leg muscle strength or mass. Objective: We determined the relationship between gait speed and (1) leg muscle strength measured at 3 lower extremity joints and (2) leg lean tissue mass (LTM) in healthy young (age: 25 years, n = 20) and old (age: 70 years, n = 20) adults. Methods: Subjects were tested for maximal isokinetic hip, knee, and ankle extension torque, leg LTM by bioimpedance, and gait performance (i.e., gait speed, stride length) at preferred and maximal gait speeds. Results: We found no evidence for a preferential relationship between gait performance and leg muscle strength compared with gait performance and leg LTM in healthy young and old adults. In old adults, hip extensor strength only predicted habitual gait speed (R2 = 0.29, p = 0.015), whereas ankle plantarflexion strength only predicted maximal gait speed and stride length (both R2 = 0.40, p = 0.003). Conclusions: Gait speed did not preferentially correlate with leg muscle strength or leg LTM, favoring neither outcome for predicting mobility. Thus, we recommend that both leg muscle strength and leg LTM should be tested and trained complementarily. Further, hip and ankle extension torque predicted gait performance, and thus we recommend to test and train healthy old adults by functional integrated multiarticular rather than monoarticular lower extremity strength exercises.

The purpose of this study is to investigate changes in leg joint coordination, intersegmental dynamics, and their relation in infants born preterm (PT) during the first months of life. Kicking actions were analyzed of 11 infants born PT at 6 and 15-weeks corrected age (CA) using three-dimensional kinematics and kinetics; results were compared to the kicking actions of 10 infants born full-term (FT). Both groups changed from a predominately in-phase coordination at 6-weeks CA to a less in-phase coordination at 15-weeks CA, however, at 6-weeks CA, infants born PT demonstrated less in-phase coordination of their ankle joints with their hip and knee joints. Between groups and across ages, both groups demonstrated consistent net and partitioned joint torque profiles, however, at 6-weeks CA infants born PT demonstrated more complex patterns of torque components. In both groups, less in-phase hip-knee coordination was associated with reduced active knee muscle torque and increased passive knee torques, however, passive knee torques had a greater influence on the kicks of infants born PT at 6-weeks CA. At 6-weeks CA, infants born PT, compared to FT, generated kicks with less in-phase hip-knee coordination, hip excursion, hip angular velocity, and hip muscle torque impulse. By 15-weeks CA, differences resolved in all variables except hip muscle torque impulse. These results highlight a different trajectory of leg joint coordination and torque production for infants born PT compared to FT.

The purpose of this study was to evaluate the efficacy of inertial training with different external loads using a new original device - the Inertial Training and Measurement System (ITMS). Forty-six physical education male students were tested. The participants were randomly divided into three training groups and a control group (C group). The training groups performed inertial training with three different loads three times weekly for four weeks. The T0 group used only the mass of the ITMS flywheel (19.4 kg), the T5 and T10 groups had an additional 5 and 10 kg on the flywheel, respectively. Each training session included three exercise sets involving the shoulder joint adductors. Before and after training, the maximal torque and power were measured on an isokinetic dynamometer during adduction of the shoulder joint. Simultaneously, the electromyography activity of the pectoralis major muscle was recorded. Results of the study indicate that ITMS training induced a significant increase in maximal muscle torque in the T0, T5, T10 groups (15.5%, 13.0%, and 14.0%, respectively). Moreover, ITMS training caused a significant increase in power in the T0, T5, T10 groups (16.6%, 19.5%, and 14.5%, respectively). The percentage changes in torque and power did not significantly differ between training groups. Electromyography activity of the pectoralis major muscle increased only in the T0 group after four weeks of training. Using the ITMS device in specific workouts allowed for an increase of shoulder joint adductors torque and power in physical education students.

Neuromuscular electrical stimulation (NMES) is a physical therapy intervention used to treat muscle weakness. NMES-elicited forces during therapy are correlated with strength gains. Patient discomfort limits NMES-elicited forces potentially compromising strength gains and the efficacy of this invention. The purpose of this study was to determine if NMES containing two different electrical stimulation pulse durations (200 or 500 μs) affected the knee extensor muscle torques subjects tolerated. Other NMES characteristics were identical in the two conditions: monophasic square-wave pulses; 75 pulses per second; and electrical stimulation train duration of one second. The primary dependent variable of interest was the percentage of maximum voluntary isometric contraction (MVIC) tolerated. The two pulse duration conditions were tested during a single session on the opposing lower extremities of 15 subjects. Subjects tolerated 49.3 ± 18.7% of MVIC torques in the 500-μs condition versus 44.5 ± 17.9% of MVIC torques in the 200-μs condition, which was a statistically significant difference (p = 0.02). Further research is needed to explore if the differences observed in this study would lead to clinically significant differences in strength gains and to see if the findings of this study can be generalized to other forms of NMES that contain other types of wave forms.

BACKGROUND: Although a number of studies have compared the influence of different electrical pulse parameters on maximum electrically induced torque (MEIT) and discomfort, the role of phase duration has been poorly investigated. OBJECTIVE: To examine the variation in muscle torque and discomfort produced when electrically stimulating quadriceps femoris using pulsed current with three different phase durations in order to establish whether there are any advantages or disadvantages in varying the phase duration over the range examined. METHOD: This is a two repeated-measures, within-subject study conducted in a research laboratory. The study was divided into 2 parts with 19 healthy young adults in each part.In part 1, MEIT was determined for each phase duration (400, 700, and 1000 µs), using a biphasic pulsed current at a frequency of 50 Hz. In part 2, stimulus amplitude was increased until the contractions reached 40% of maximum voluntary isometric contraction (MVIC) and the associated discomfort produced by each phase duration was measured. RESULTS: In part 1 of the study, we found that the average MEITs generated with each phase duration (400, 700, and 1000 µs) were 55.0, 56.3, and 58.0% of MVIC respectively, but the differences were not statistically significant (p=.45). In part 2, we found a statistically significant increase in discomfort over the same range of phase durations. The results indicate that, for a given level of torque production, discomfort increases with increasing phase duration (p=.008). CONCLUSIONS: Greater muscle torque cannot be produced by increasing the stimulus phase duration over the range examined. Greater discomfort is produced by increasing the stimulus phase duration.

INTRODUÇÃO: A influência dos efeitos do calor no torque em indivíduos de ambos os gêneros é desconhecida, principalmente quando associado à estimulação elétrica. OBJETIVOS: Analisar o efeito da diatermia por ondas curtas no torque do músculo quadríceps femoral gerado pela contração voluntária e eletricamente induzida em indivíduos assintomáticos de ambos os gêneros e avaliar o desconforto gerado pela corrente elétrica. MÉTODOS: Participaram do estudo 26 voluntários, onde foi avaliada a capacidade de produção de torque em um dinamômetro isocinético através de contrações isométricas voluntárias máximas (CIVM) e eletricamente induzida (TEI). Os voluntários foram submetidos a quatro momentos: mensuração do torque através de contração voluntária, contração voluntária após aplicação do calor, contração eletricamente induzida e contração eletricamente induzida após aplicação do calor. O desconforto sensorial durante a estimulação elétrica foi avaliado com a escala visual analógica (EVA). RESULTADOS: O torque no sexo masculino foi maior quando submetido à aplicação da corrente elétrica associado ao calor (p = 0,030). Em relação ao desconforto gerado pela corrente elétrica, foi observado aumento no sexo feminino quando associado ao calor (p = 0,044) comparado ao sexo masculino. CONCLUSÃO: A diatermia por ondas curtas não influenciou o torque produzido pela contração voluntária, porém houve aumento do torque eletricamente induzido (TEI) após aplicação de calor em indivíduos do sexo masculino e aumento do desconforto sensorial gerado pela corrente apenas nos sujeitos do sexo feminino. INTRODUCTION: The influence of the heat effects on muscle torque in males and females is still unknown, especially when associated with electrical stimulation. OBJECTIVES: To assess the effects of shortwave diathermy on voluntary and electrically induced torque in healthy males and females, and to assess the discomfort produced by electrical stimulation. METHODS: Twenty-six subjects participated in the study. Voluntary and electrically induced torque was assessed using an isokinetic dynamometer. The subjects were asked to attend 4 different sessions: measurement of maximal voluntary contraction (MVC); MVC after SWD; maximal electrically induced torque (MEIT); MEIT after SWD. Discomfort during MEIT was measured using a visual analogue scale. RESULTS: MEIT was higher in males after SWD (p = 0.030) Females presented more discomfort during MEIT after SWD application (p = 0.044) when compared to males. CONCLUSION: SWD did not affect the MVC; however, there was increase in MEIT after SWD in males and discomfort increase in females.

Contains fulltext : 174808.pdf (Publisher’s version ) (Open Access) BACKGROUND: Therapeutic management of upper extremity (UE) function of boys and men with Duchenne Muscular Dystrophy (DMD) requires sensitive and objective assessment. Therefore, we aimed to measure physiologic UE function of healthy subjects and DMD patients in different disease stages, and to evaluate the relation between these physiologic measures and functional UE scales. METHODS: Twenty-three DMD patients and twenty healthy controls (7-23 years) participated in this explorative case-control study. Maximal muscle torque, maximal and normalized surface electromyography (sEMG) amplitudes, muscle thickness, echogenicity and maximal passive and active joint angles were measured. At activity level, Brooke upper extremity rating scale and the Performance of Upper Limb (PUL) scale were used. RESULTS: Outcome measures related to proximal UE function could discriminate between disease stages. Increased normalized sEMG amplitudes were found in patients, even in early disease stages. Maximal active joint angles showed the strongest relation to Brooke scale (R 2 = 0.88) and PUL scale (R 2 = 0.85). CONCLUSIONS: The decline of muscle functions precedes the decline in performance of UE activities, and therefore may play a role in early detection of UE limitations. Increased sEMG levels demonstrate that DMD patients use more of their muscle capacity compared to healthy subjects, to perform daily activities. This might result in increased fatigability. Active maximal joint angles are highly related to functional scales, so preserving the ability to use the full range of motion is important for the performance of daily activities. Close monitoring of active joint angles could therefore help in starting interventions that minimize functional UE decline in DMD patients timely.

Determining muscle contractile properties following exercise is critical in understanding neuromuscular function. Following high intensity training, individuals often experience exercise induced muscle damage (EIMD). The purpose of this investigation was to determine the effect of whole-body vibration (WBV) on muscle contractile properties following EIMD. Twenty-seven females volunteered for 7 sessions and were randomly assigned to a treatment or control group. Muscle contractile properties were assessed via voluntary torque (VT), peak twitch torque (TT), time to reach peak torque, half relaxation time of twitch torque, percent activation (%ACT), rate of rise (RR), rate of decline (RD), mean and peak electromyography during maximum voluntary isometric contraction. Two testing sets were collected each day, consisting of pre measures followed by WBV or control and post measures. A mixed factor analysis of variance was conducted for each variable. %ACT measures found baseline being less than day 1 in both measures in the control group. TT was found to be greater in the control group compared to WBV group. TT and VT baseline measures were greater than all other time points. RR showed control group had higher values than WBV group. These results indicate that WBV following EIMD had some positive effects on muscle contractile properties.

Detection of the moment when a muscle begins to activate on the basis of EMG signal is important task for a number of biomechanical studies. In order to provide high accuracy of EMG onset detection, we developed novel method, that give results similar to that obtained by an expert. By means of this method, EMG is processed in two stages. The first stage gives rough estimation of EMG onset, whereas the second stage performs local, precise searching. The method was applied to support signal processing in biomechanical study concerning effect of body position on EMG activity and peak muscle torque stabilizing spinal column under static conditions

This study was conducted to identify factors other than morphological muscle strength factors that affect injured and uninjured sides of knee flexors with anterior cruciate ligament (ACL) lesions.The study population consisted of 22 patients with ACL lesions. Their hamstring muscle volume was measured on MRI, and muscle torque per muscle volume was calculated as the peak torque of knee flexion divided by hamstring muscle volume.The mean muscle torque per unit volume of hamstrings in patients with ACL rupture was 0.09 ± 0.02 Nm/cm(3) at 60°/s and 0.08 ± 0.01 Nm/cm(3) at 180°/s on the injured side, and 0.11 ± 0.02 Nm/cm(3) at 60°/s and 0.08 ± 0.01 Nm/cm(3) at 180°/s on the uninjured side. The mean muscle torque per unit volume of hamstrings in control subjects was 0.11 ± 0.02 Nm/cm(3) at 60°/s and 0.08 ± 0.03 Nm/cm(3) at 180°/s. One-factor ANOVA analysis found no significant differences between the three groups at either flexion velocity.Neurological dysfunction does not appear to exist in knee flexor muscles after ACL injury, unlike the quadriceps. Since the mechanism of muscle weakness will differ depending on the muscle, it is important for clinicians to take this discrepancy into consideration.II.

We hypothesized that patella eversion during total knee arthroplasty (TKA) reduces early return of active knee extension and flexion, quadriceps muscle strength, and postoperative pain. In 100 conventional TKA knees and 100 minimally invasive TKA (MIS TKA) knees, we compared knee range of motion (ROM), postoperative pain, and quadriceps muscle strength at 1 day, 4 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 12 weeks, 1 year, and 5 years after surgery. The differences of surgical approach between MIS TKA and conventional TKA of this study are length of skin incision with subcutaneal flap and patella eversion. In MIS TKA, skin incision is shorter than conventional TKA. Furthermore, patella is not everted in MIS TKA procedure. There were no significant differences in preoperative factors. Postoperative improvement of ROM, postoperative muscle strength recovery, and postoperative improvement of visual analog scale were faster in patients with MIS TKA when compared to that in patients with conventional TKA. On the other hand, no significant difference was observed in complication, 5-year clinical results of subjective knee function score, and the postoperative component angle and lower leg alignment. These results indicate that patella eversion may affect muscle strength recovery and postoperative pain.

Purpose: This study investigated whether muscle fatigue during functional electrical stimulation (FES)-induced cycling was associated with changes occurring in evoked electromyographic signals (eEMG, M-waves) in individuals with spinal cord injury. We also explored the effects of recovery intervals between exercise sessions on the relationship between eEMG and muscle torque. Methods: Eight individuals with spinal cord injury performed three FES-cycling sessions of 15-min duration, with 5 min of recovery between them. The quadriceps muscles were electrically stimulated as the prime agonist to produce cycling. Pedal torques and surface eEMG signals were synchronously processed and recorded for offline analysis. Results: Large Torque decreases (20–44%) were observed in the first 5 min of cycling during the three exercise bouts, while changes of similar magnitude did not occur on any of the M-wave time-series (less than 19%). Between 5 and 15 min of cycling, muscle fatigue lowered the plateau baselines of Torque (ranging from 41% to 62%), M-wave peak-to-peak amplitude (PtpA) and Area (ranging from 60% to 98%) time-series, yet the magnitudes of these reductions were not consistent between them. Conclusion: We concluded that muscle fatigue during FES-cycling was not associated with, nor could be predicted by, eEMG signals. Nonetheless, the consistency between M-waves and Torque time-curves in their direction of change clearly warrants further investigation.

The purpose of this study was to evaluate motor unit recruitment in the quadriceps femoris (QF) after anterior cruciate ligament (ACL) rupture and repair. Subjects included 24 patients at ≥ 18 months after ACL reconstruction and 22 control subjects with no history of knee injury. A series of cross-sectional magnetic resonance images were obtained to compare the QF of patients' injured side with that of their uninjured sides and that of uninjured control subjects. Muscle torque per muscle volume was calculated as isokinetic peak torque divided by QF muscle volume (cm(3)). The mean muscle torque per unit volume of the injured side of patients was not significantly different from that of the uninjured side or control subjects (one-way ANOVA) Results of the present study were contrary to the results of a previous study that evaluated patients at ≤ 12 months after ACL reconstruction. The present study found that high-threshold motor unit recruitment was restored at ≥ 18 months after ACL reconstruction. Thus, clinicians must develop techniques that increase the recruitment of high-threshold motor units in the QF from the period immediately after the injury until approximately 18 months after ACL reconstruction.