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  1. 8 Journal of Human Kinetics

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1
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Acute neuromuscular responses to a resistance exercise session performed using the DeLorme and Oxford techniques

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Pereira R., Mendel M. M. A., Schettino L., Machado M., Augusto-Silva P.
Human Movement
|
2013
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vol. 14
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issue 4
347-352
EN
Purpose. The purpose of this study was to examine and compare acute neuromuscular behavior during a resistance exercise session (RES) conducted with the DeLorme and Oxford techniques. Methods. Seven healthy and trained participants volunteered to carry out two RES, one week apart, of unilateral elbow flexion. Each session was conducted with the DeLorme or Oxford techniques in a counterbalanced order. Electromyographic (EMG) data were recorded from the biceps brachii (BB) and triceps brachii (TRIC) during a maximal isometric voluntary contraction. Normalized EMG amplitude from BB and TRIC and the co-contraction ratio (CCR) during the concentric and eccentric phases were calculated. Results. The EMG amplitude from BB and TRIC as well as the CCR of both the concentric and eccentric phases were similar in both techniques. Additionally, normalized EMG amplitude from BB was higher during the concentric phase when compared with the eccentric phase for both techniques, supporting the hypotheses of distinct neural control for concentric and eccentric phases of movement. The DeLorme and Oxford techniques induced similar acute neuromuscular responses during the RES. Conclusions. Our results may support previous findings on similar strength gains after resistance training performed with both analyzed techniques.
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Neuromuscular Responses of Elite Skaters During Different Roller Figure Skating Jumps

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Pantoja P. D., Mello A., Liedtke G. V., Kanitz A. C., Cadore E. L., Pinto S. S., Alberton C. L., Kruel L. F. M.
Journal of Human Kinetics
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2014
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vol. 41
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issue 1
23-32
EN
This study aimed to describe the neuromuscular activity of elite athletes who performed various roller figure skating jumps, to determine whether the muscle activation is greater during jumps with more rotations and in which phase the muscles are more active. This study also aimed to analyze if there is any difference in the muscle activity pattern between female and male skaters. Four elite skaters were evaluated, and each participated in two experimental sessions. During the first session, anthropometric data were collected, and the consent forms were signed. For the second session, neuromuscular data were collected during jumps, which were performed with skates at a rink. The following four roller figure skating jumps were evaluated: single Axel, double Axel, double Mapes and triple Mapes. The neuromuscular activity of the following seven muscles was obtained with an electromyograph which was fixed to the waist of each skater with a strap: biceps femoris, lateral gastrocnemius, tibialis anterior, rectus femoris, vastus lateralis, vastus medialis and gluteus maximus. The signal was transmitted wirelessly to a laptop. During the roller figure skating jumps, the lateral gastrocnemius, rectus femoris, vastus lateralis, biceps femoris and gluteus maximus, showed more activation during the jumps with more rotations, and the activation mainly occurred during the propulsion and flight phases. Female skaters demonstrated higher muscle activities in tibialis anterior, vastus lateralis, vastus medialis and gluteus maximus during the landing phase of the triple Mapes, when compared to their male counterparts. The results obtained in this study should be considered when planning training programs with specific exercises that closely resemble the roller figure skating jumps. This may be important for the success of elite skaters in competitions.
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Lower Extremity Muscle Activity During a Women's Overhand Lacrosse Shot

100%
Millard B. M., Mercer J. A.
Journal of Human Kinetics
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2014
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vol. 41
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issue 1
15-22
EN
The purpose of this study was to describe lower extremity muscle activity during the lacrosse shot. Participants (n=5 females, age 22±2 years, body height 162.6±15.2 cm, body mass 63.7±23.6 kg) were free from injury and had at least one year of lacrosse experience. The lead leg was instrumented with electromyography (EMG) leads to measure muscle activity of the rectus femoris (RF), biceps femoris (BF), tibialis anterior (TA), and medial gastrocnemius (GA). Participants completed five trials of a warm-up speed shot (Slow) and a game speed shot (Fast). Video analysis was used to identify the discrete events defining specific movement phases. Full-wave rectified data were averaged per muscle per phase (Crank Back Minor, Crank Back Major, Stick Acceleration, Stick Deceleration). Average EMG per muscle was analyzed using a 4 (Phase) x 2 (Speed) ANOVA. BF was greater during Fast vs. Slow for all phases (p<0.05), while TA was not influenced by either Phase or Speed (p>0.05). RF and GA were each influenced by the interaction of Phase and Speed (p<0.05) with GA being greater during Fast vs. Slow shots during all phases and RF greater during Crank Back Minor and Major as well as Stick Deceleration (p<0.05) but only tended to be greater during Stick Acceleration (p=0.076) for Fast vs. Slow. The greater muscle activity (BF, RF, GA) during Fast vs. Slow shots may have been related to a faster approach speed and/or need to create a stiff lower extremity to allow for faster upper extremity movements.
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Kinesiological Analysis of Stationary Running Performed in Aquatic and Dry Land Environments

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Lima Alberton C., Santana Pinto S., Silva Azenha N. A. d., Cadore E. L., Peikriszwili Tartaruga M., Brasil B., Martins Kruel L. F.
Journal of Human Kinetics
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2015
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vol. 49
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issue 1
5-14
EN
The purpose of the present study was to analyze the electromyographic (EMG) signals of the rectus femoris (RF), vastus lateralis (VL), semitendinosus (ST) and short head of the biceps femoris (BF) during the performance of stationary running at different intensities in aquatic and dry land environments. The sample consisted of 12 female volunteers who performed the stationary running exercise in aquatic and dry land environments at a submaximal cadence (80 beats·min-1 controlled by a metronome) and at maximal velocity, with EMG signal measurements from the RF, VL, ST and BF muscles. The results showed a distinct pattern between environments for each muscle examined. For the submaximal cadence of 80 beats·min-1, there was a reduced magnitude of the EMG signal in the aquatic environment, except for the ST muscle, the pattern of which was similar in both environments. In contrast to the submaximal cadence, the pattern of the EMG signal from all of the muscles showed similar magnitudes for both environments and phases of movement at maximal velocity, except for the VL muscle. Therefore, the EMG signals from the RF, VL, ST and BF muscles of women during stationary running had different patterns of activation over the range of motion between aquatic and dry land environments for different intensities. Moreover, the neuromuscular responses of the lower limbs were optimized by an increase in intensity from submaximal cadence to maximal velocity.
5
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The Effects of Bag Style on Muscle Activity of the Trapezius, Erector Spinae and Latissimus Dorsi During Walking in Female University Students

100%
Hardie R., Haskew R., Harris J., Hughes G.
Journal of Human Kinetics
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2015
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vol. 45
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issue 1
39-47
EN
Back pain is common in adolescents which has been associated with carrying a bag. However, there is little research examining the effects of bag style in female adolescents. The aim of the study was to investigate the effects of different bag conditions on muscle activity of the trapezius, erector spinae and latissimus dorsi muscles in female university students during walking. Twelve female university students walked on a treadmill for 5 minutes at 1.1 m/s during five conditions; control, 1 strapped rucksack, 2 strapped rucksack, ipsilateral shoulder strap and contralateral shoulder strap, each containing 10% bodyweight. Electromyography for the trapezius, erector spinae and latissimus dorsi was recorded for the last 30 s of each condition. Two-way ANOVA and paired t-tests were used to identify differences between right and left muscles and between bag conditions. Results showed that muscle activity of the left trapezius was significantly higher than the right trapezius during the 1 strap rucksack condition. For the left trapezius, the 2 strapped rucksack and the control condition had significantly lower muscle activity compared to the 1 strapped rucksack and the ipsilateral shoulder strap. For the left erector spinae muscle, there was significantly greater muscle activity when wearing the contralateral shoulder strap compared to the control. For the right erector spinae, significantly lower muscle activity was observed when wearing the 2 strapped rucksack compared to the ipsilateral shoulder strap and contralateral shoulder strap. There were no significant differences in muscle activity of the latissimus dorsi muscles between any of the bag conditions. These findings suggest that a two strapped rucksack should be used when carrying loads to reduce spinal muscle activity which may, in turn, reduce reports of back pain in female adolescents.
6
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Relations between Bioelectrical Muscles Activity and Isokinetic Strength Parameters in 17-19-Year-Old Judoists

100%
Dornowski M.
Baltic Journal of Health and Physical Activity
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2010
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vol. 2
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issue 1
43-48
EN
Background: Muscle strength as an element of preparation and sport competition is one of the most important aspects in technical and tactical efficiency. The aim of this study was to define the level of relation between bioelectrical muscle activity and isokinetic strength parameters in 17-19-year-old judoists.Material/Methods: 30 judo athletes (17-19-year-old) took part in the research. The research was conducted in Gdańsk Academy of Physical Education and Sport Laboratory during 2006-2008. In the research authors used: to evaluate the isokinetic strength level, "Concept 2 Dyno" device was used in the research, along with surface summary electrical bio-potentials reading on EMG AMT-8 CDN BORTEC BIOMEDICAL with ACQ software.Results: In the upper right limb there are more statistical significant correlations between isokinetic strength parameters and electrical muscle activities.In the lower limbs measurement of the left leg shows more significant correlations.Conclusions: Comparing the upper and lower limbs, it was noticed that the isokinetic strength parameters of the upper limbs are more correlated with the measured muscle electrical activities.Regarding the left and the right side comparison, the right side (the upper and the lower limb) isokinetic strength parameters are more correlated with the measured muscle activities.
7
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Content available

Graciloplasty, electrostimulation, electromyography. Clinical implications of electrophysiological phenomena in the neo-sphincter created from the gracilis mus

100%
Romaniszyn M., Wałęga P.
Polish Journal of Surgery
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2016
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vol. 88(2)
68-76
EN
The aim of the study was to compare the electrophysiological phenomena occurring in the gracilis muscle, transposed into the pelvic floor during the graciloplasty procedure, subjected to continuous electrical stimulation by means of implanted stimulator, or regular stimulation by means of an external device, as well as the long-term functional results of the graciloplasty procedure. Material and methods. A total of 27 patients were included in the analysis. The study group consisted of 7 patients after dynamic graciloplasty, 11 patients after graciloplasty followed by transrectal stimulation, 4 patients after graciloplasty with transcutaneous stimulation, and 5 patients after graciloplasty without any stimulation. All patients had a surface electromyographic examination of the transposed gracilis muscle performed, the signal for each patient was compared to the signal acquisited from a non-transposed gracilis in the same patient. In addition, each subject underwent a clinical operation results assessment, as well as an anorectal manometry examination. Results. In the electromiographic examination, the mean frequency of motor units action potentials of the gracilis muscle in the thigh was 64 Hz, and in the muscle after transposition and stimulation period mean frequency was 62 Hz. There was no statistically significant difference in the frequency of action potentials before and after treatment in any of the analyzed groups, or between groups with different methods of stimulation (p> 0.05). We found a significant correlation between the clinical outcome of the procedure, and the average amplitude of the EMG signal from the transposed muscle, as well as between the amplitude of the EMG signal and the basal pressure in the anal canal in manometric examination. There were no significant correlations in the remaining manometric parameters. Conclusions. Despite the different methods of postoperative stimulation, including expensive implantable stimulators, there was no difference in the electrical activity between the transposed gracilis muscle, and the gracilis muscle left in situ. There was no signoficant advantage of the dynamic graciloplasty procedure over the graciloplasty with transanal or transcutaneous stimulation.
8
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Content available

A Single-Blind Randomized Controlled Trial Investigating Changes in Electrical Muscle Activity, Pain, and Function after Shockwave Therapy in Chronic Non-Specific Low Back Pain: Pilot Study

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Elgendy M. H., Mohamed M., Hussein H. M.
|
|
vol. 24(2)
87-94
EN
Background. To investigate the effect of adding r-ESWT to a standard exercise program of chronic non-specific LBP on electrical muscle activity (EMG), pain and function. Materials and methods. Our single-blind randomized controlled trial enrolled 30 patients with chronic non-specific LBP randomly allocated to an r-ESWT (n=15) group and a control group (n=15). All patients received a standard exercise program, while r-ESWT was additionally administered in the r-ESWT group. EMG activity, pain and function were assessed before and after 6 weeks of treatment. Results. After treatment, all outcome measures were significantly different (p < 0.05). The addition of r-ESWT produced a significant increase in EMG activity (of all muscles tested) and a reduction in pain intensity and functional disability scores (p < 0.05) compared to the control group. Conclusions. 1. A standard intervention offered either alone or with r-ESWT increased EMG activities, reduced pain, and enhanced function in patients with chronic non-specific LBP. 2. Adding r-ESWT to the standard intervention program might produce better results.
9
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The Short and Long Term Effects of Tibialis Anterior Local Cooling on Dorsiflexion Force

100%
Pereira L., Pereira R., Neto O., Magini M.
Journal of Human Kinetics
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2010
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vol. 26
65-71
EN
The goal of this study was to analyze and compare the superficial temperature, dorsiflexion force and electromyographic (EMG) signal of tibialis anterior muscle before and after superficial cooling application. Seventeen healthy untrained volunteers were divided into two groups. Subjects were submitted to seven procedures of maximal voluntary isometric contractions of dorsiflexion, once before and six times after thirty minutes of either superficial cooling of the anterolateral side of the leg with an ice pack (LC group) or rest (control group). Superficial temperature, dorsiflexion force and EMG of the tibialis anterior muscle were evaluated immediately, 5, 15, 30, 45 and 60 minutes after cooling intervention. The results showed that the superficial temperature reduced significantly for 60 minutes post cooling, dorsiflexion force and amplitude of EMG signal was reduced only immediately after cooling application, whereas median frequency of EMG signal was significantly reduced up to 60 minutes post cooling application. The study concludes that superficial cooling with ice pack for thirty minutes can decrease the dorsiflexion force and EMG activity only immediately after the cooling application, while it causes a prolonged decrement on the superficial local temperature and on the median frequency of the EMG signal. These findings suggest that clinicians should be aware of the immediately alterations in motor output performance that result from muscle local cooling interventions which are followed by rapid recovery.
10
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Differences in bioelectrical activity of quadriceps muscle during various types of contraction

100%
Niespodzinski B., Lukowicz M., Mieszkowski J.
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EN
Background: The aim of the study was to estimate differences in bioelectrical activity between rectus femoris (RF) and vastus medialis (VM) muscles of each lower limb. Material/Methods: 29 female and 18 male adult subjects participated in the study. Each subject performed the following quadriceps contractions with each lower limb: concentric, isometric, eccentric and 30-sec. long maximal voluntary isometric contraction. 3 parameters were obtained in surface electromyography (SEMG): mean RMS amplitude (RMS), mean percentage value of maximal voluntary contraction (%MVC) and mean frequency (MF). Results: RF occurred to have a lower percentage activity (-28.43%) and absolute amplitude (- 36.57%) value than VM during all three basic forms of contraction against gravity. Except the RMS values for concentric contraction, all the mentioned parameters were significantly different. In contrast, RF had a higher MF rate than VM. Differences were at the mean level of 22.57% for all activities. Conclusions: There are no differences in SEMG of quadriceps muscle between both lower limbs. VM and RF differ from each other in RMS, %MVC and MF during all types of studied contractions.
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Effects of Fatigue Induced by Prolonged Gait When Walking on the Elderly

88%
Pereira M., Gonçalves M.
Human Movement
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2011
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vol. 12
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issue 3
242-247
EN
Purpose. Fatigue has been pointed as a fall risk in the elderly; however, the effects of prolonged gait on neuromuscular recruitment and on its pattern remain unknown. The aim of this study was to evaluate the effects of prolonged gait on neuromuscular recruitment levels and spatial-temporal gait variables. Methods. Eight healthy older women (age: 72.63 ± 6.55 years) walked at their preferred walking speed for twenty minutes on a treadmill. The Root Mean Square (RMS) from the vastus-lateralis, femoral biceps, tibialis anterior and lateral gastrocnemius muscles were determined at the first and last minute of the test during the moments of Heel Strike (HS), Terminal Stance and Terminal Swing (TS). In addition, coactivation in the knee and ankle as well as the stride cadence and length were measured in the test. The two RMS data (taken at the first and last minute) were compared by means of a Student's t-test. Results. Twenty minutes of walking induced fatigue in the subjects, as observed through an increase in RMS, notably during the HS and TS. Coactivation was also influenced by the prolonged gait test. The only gait phase where a risk of falling was enhanced was the HS. Nonetheless, subjects developed strategies to maintain a safe motor pattern, which was evidenced by an increase in stride length and a decrease in stride cadence. Conclusion. Tests lasting just twenty minutes on a treadmill were enough to induce fatigue in older adults. However, the level of fatigue was not enough to present a danger or fall risk to elderly individuals.
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Effects of Elbow Flexor Muscle Resistance Training on Strength, Endurance and Perceived Exertion

88%
Gonçalves M., Souza Castelo Oliveira A.
Human Movement
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2013
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vol. 14
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issue 2
110-115
EN
Purpose. To verify the effects of resistance training at the electromyographic fatigue threshold (EMGFT) based on one-repetition maximum strength (1RM), heart rate (HR), rate of perceived exertion (PE) and endurance time (EndT). Methods. Nineteen subjects (training group [TG]: n = 10; control group [CG]: n = 9), performed 1-min bicep curl exercises sets at 25%, 30%, 35% and 40% 1RM. Electromyography (biceps brachii and brachiorradialis), HR and PE were registered. Biceps brachii EMGFT was used to create a load index for an eight-week resistance training programme (three sets until exhaustion/session, two sessions/week) for the TG. The CG only attended one session in the first week and another session in the last week of the eight-week training period for EndT measurement. EndT was determined from the number of repetitions of each of the three sets performed in the first and last training sessions. After training, 1RM, EMGFT, EndT, HR and PE at the different bicep curl load intensities were again measured for both groups. Results. Increases in 1RM (5.9%, p < 0.05) and EndT (> 60%, p < 0.001) after training were found. In addition, PE was reduced at all load intensities (p < 0.05), while no changes were found for HR and EMGFT after training. Conclusions. Strength-endurance training based on the EMGFT improved muscular endurance and also, to a lesser extent, muscular strength. Moreover, the reduced levels of physical exertion after training at the same intensity suggest that endurance training exercises may improve comfort while performing strength exercises.
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The Effects of a Perturbation-Based Balance Training on the Reactive Neuromuscular Control in Community- -Dwelling Older Women: A Randomized Controlled Trial

88%
Rossi L. P., Pereira R., Brandalize M., Gomes A. R. S.
Human Movement
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2013
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vol. 14
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issue 3
238-246
EN
Purpose. The purpose of this study was to evaluate the effects of short-term perturbation-based balance training and a detraining period on postural control in older adults. Methods. A group of healthy older women were recruited and divided into two groups: an exercise group (EG, n = 21, age = 67.0 ± 2.0 y) that performed balance-based exercises three times a week over a sixweek period and a control group (CG, n = 20, age = 67.9 ± 3.1 y). Center-of-pressure displacement (CoP) and electromyographic data (EMG onset, time-to-peak and amplitude) were assessed during forward and backward perturbations for six leg muscles. All variables were analyzed before the training program began, at its end, and after a six-week period of detraining. A mixed ANOVA model was used to analyze the within- and between-subject results. Results. A decrease in backward CoP displacement, EMG onset and time-to-peak of the ankle muscles, especially the tibialis anterior (TA) and gastrocnemius (MG), was observed. Improvement in muscle EMG amplitude for the ankle muscles (TA, MG and Soleus - SO) at the early phase (0-200 ms) of the perturbation test, with the SO also showing an increase in amplitude at the intermediate phase (201-400 ms). After the detraining period, only the TA muscle maintained an improvement in reaction time. Conclusions. Perturbation-based balance training improved neuromuscular responses such as muscle reaction time and ankle muscle activation and consequently aided the body’s ability to maintain correct center of pressure, although after a period of detraining this gain was not maintained for most of the assessed variables.
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The Gluteus Medius Vs. Thigh Muscles Strength Ratio and Their Relation to Electromyography Amplitude During a Farmer’s Walk Exercise

88%
Stastny P., Lehnert M., Zaatar A., Svoboda Z., Xaverova Z., Pietraszewski P.
Journal of Human Kinetics
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2015
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vol. 45
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issue 1
157-165
EN
The strength ratio between hamstrings and quadriceps (H/Q) is associated with knee injuries as well as hip abductor muscle (HAB) weakness. Sixteen resistance trained men (age, 32.5 ± 4.2 years) performed 5 s maximal isometric contractions at 75° of knee flexion/extension and 15° of hip abduction on a dynamometer. After this isometric test they performed a Farmer´s walk exercise to find out if the muscle strength ratio predicted the electromyography amplitude expressed as a percentage of maximum voluntary isometric contraction (%MVIC). The carried load represented a moderate intensity of 75% of the exercise six repetitions maximum (6RM). Electromyography data from the vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF) and gluteus medius (Gmed) on each leg were collected during the procedure. The groups selected were participants with H/Q ≥ 0.5, HQ < 0.5, HAB/H ≥ 1, HAB/H < 1, HAB/Q ≥ 0.5 and HAB/Q < 0.5. One way ANOVA showed that Gmed activity was significantly greater in the group with HAB/H < 1 (42 ± 14 %MVIC) as compared to HAB/H ≥ 1 (26 ± 10 %MVIC) and HAB/Q < 0.5 (47 ± 19 %MVIC) compared to HAB/Q ≥ 0.5 (26 ± 12 %MVIC). The individuals with HAB/H < 1 were found to have greater activation of their Gmed during the Farmer’s walk exercise. Individuals with HAB/Q < 0.5 had greater activation of the Gmed. Gmed strength ratios predict the muscle involvement when a moderate amount of the external load is used. The Farmer’s walk is recommended as an exercise which can strengthen the gluteus medius, especially for individuals with a HAB/H ratio < 1 and HAB/Q < 0.5.
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Muscle Activation Profiles of Lower Extremities in Different Throwing Techniques and in Jumping Performance in Elite and Novice Greek Judo Athletes

88%
Zaggelidis G., Lazaridis S.
Journal of Human Kinetics
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2013
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vol. 37
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issue 1
63-70
EN
The aim of this study was to examine the neuromuscular adaptations of knee muscles during hip throwing techniques and vertical jumps in elite and novice Greek judokas. Ten elite and ten novice judokas performed two hip throws and different vertical jumping tasks. Surface electromyograms were recorded from vastus lateralis and biceps femoris muscles along with generated kinetics. Elite judokas revealed higher EMG activity of agonist muscles during throws and jumps but lower co-activation levels. Better jumping performance, better utilisation of the stretch-shortening cycle mechanism, higher and earlier generated pushoff forces and shorter contact time periods characterized elite judokas. Total neuromuscular activation that adopt elite judokas reveals a more mature and skill dependent strategy compared to novice ones.
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Effects of workload level on muscle recruitment in cycling

88%
Priego J. I., Bini R. R., Lanferdini F. J., Carpes F. P.
Human Movement
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2014
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vol. 15
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issue 1
45-50
EN
Purpose. Despite the volume of studies addressing muscle activation during pedaling, it is unclear whether changes in workload level during cycling could dictate motor unit recruitment. The present study investigated the frequency content of lower limb muscle activation during submaximal workloads. Methods. Twelve male competitive cyclists pedaled at three workload levels: (1) maximum aerobic power output (POMAX), (2) first ventilatory threshold (POVT1), and (3) second ventilatory threshold (POVT2). Muscle activation was recorded from the right vastus medialis (VM), rectus femoris (RF), long head of biceps femoris (BF), tibialis anterior (TA), gastrocnemius medialis (GM), and soleus (SOL) muscles. Data from muscle activation were assessed using frequency band analysis. High and low frequencies and overall muscle activation were normalized to that collected at POMAX. Results. Greater overall activation was observed for VM (27%, p < 0.01, d = 1.22), RF (24%, p < 0.01, d = 0.96), BF (33%, p < 0.01, d = 1.43), GM (10%, p < 0.05, d = 0.91), and SOL (16%, p < 0.05, d = 0.81) at POVT2 than POVT1. No differences were observed in the high or low frequencies relative to overall muscle activation. Conclusions. Cyclists sustain changes at submaximal workloads via an equally distributed increase in muscle activation with no potential changes in motor unit recruitment.
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Influence of Static Stretching Duration on Quadriceps Force Development and Eletromyographic Activity

88%
Rossi L., Pereira R., Simão R., Brandalize M., Gomes A.
Human Movement
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2010
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vol. 11
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issue 2
137-143
EN
Purpose. The purpose of the present study was to analyze the influence of static stretching duration on quadriceps muscle isometric force and electromyographic (EMG) activity of the rectus femoris and vastus lateralis. Basic procedures. Twenty recreationally-active healthy men were selected for the study. On two separate days, participants took part in two stretching protocols of different durations. Following a specific warmup, participants performed isometric strength assessments of the dominant leg before and after a bout of quadriceps stretching. The stretching protocol consisted of two stretches for the quadriceps muscle for three repetitions of 30 seconds on one visit, and 60 seconds on the other. Main findings. The results revealed a significant reduction in quadriceps muscle mean and peak forces and EMG activity for the rectus femoris with both 30- and 60-second stretching protocols (p ≤ 05). However, EMG activity of the vastus lateralis decreased significantly only in the 60-second protocol (p ≤ 05). Conclusions. Both stretching protocols induced significant decreases in strength and EMG activity, although the stretching duration (60 × 30) did not appear to be a major influencing factor for the current strength reductions. In this perspective, coaches and athletes should avoid flexibility training which consists in stretching repetitions of 30 seconds or longer prior to competitions.
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The Reliability of Electromyographic Normalization Methods for Cycling Analyses

75%
Sinclair J., Taylor P. J., Hebron J., Brooks D., Hurst H. T., Atkins S.
Journal of Human Kinetics
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2015
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vol. 46
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issue 1
19-27
EN
Electromyography (EMG) is normalized in relation to a reference maximum voluntary contraction (MVC) value. Different normalization techniques are available but the most reliable method for cycling movements is unknown. This study investigated the reliability of different normalization techniques for cycling analyses. Twenty-five male cyclists (age 24.13 ± 2.79 years, body height 176.22 ± 4.87 cm and body mass 67.23 ± 4.19 kg, BMI = 21.70 ± 2.60 kg·m−1) performed different normalization procedures on two occasions, within the same testing session. The rectus femoris, biceps femoris, gastrocnemius and tibialis anterior muscles were examined. Participants performed isometric normalizations (IMVC) using an isokinetic dynamometer. Five minutes of submaximal cycling (180 W) were also undertaken, allowing the mean (DMA) and peak (PDA) activation from each muscle to serve as reference values. Finally, a 10 s cycling sprint (MxDA) trial was undertaken and the highest activation from each muscle was used as the reference value. Differences between reference EMG amplitude, as a function of normalization technique and time, were examined using repeated measures ANOVAs. The testretest reliability of each technique was also examined using linear regression, intraclass correlations and Cronbach’s alpha. The results showed that EMG amplitude differed significantly between normalization techniques for all muscles, with the IMVC and MxDA methods demonstrating the highest amplitudes. The highest levels of reliability were observed for the PDA technique for all muscles; therefore, our results support the utilization of this method for cycling analyses.
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Simple Clinical Tests in Severe Carpal Tunnel Syndrome

75%
Nowak M., Noszczyk B.
Polish Journal of Surgery
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2012
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vol. 84
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issue 10
502-508
EN
Patients with severe carpal tunnel syndrome may be characterised by an atypical clinical picture. They assess complaints as becoming less bothersome than in the past. It seems that this may influence the diagnostic value of some clinical tests used in physical examinations. was the selection of the most reliable clinical tests in a group of patients with severe carpal tunnel syndrome. Material and methods. The material comprised 38 cases of severe form of the disease in a group of 37 prospective patients. The methods consisted in the evaluation of the rate of positive results of selected clinical tests, and in the comparison of their statistical correlation with selected parameters of median nerve conduction. Results. The study results indicated that high incidence of two-point discrimination disorders showed a correlation with the sensory conduction parameters, including the median-ulnar sensory latency difference. The Durkan's and Phalen's tests were positive in almost all patients with advanced carpal tunnel. The Katz hand diagram revealed significantly enhanced sensitivity in the “probable” pattern. Conclusions. We speculate that the two-point discrimination, evaluated with the use of a simple paper clip, enables the selection of a group of patients with severe form of the syndrome for further differentiation. The tool used for facilitating the differential diagnosis is the Katz hand diagram. The Durkan's and Phalen's tests have an equally high value. However, they show no correlation with the conduction parameters, as measured by EMG.
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A Study of Electromyography of Lower Extremities and Comparison of Effects of Plyometric and Isotonic Weight Training

75%
Mehdipour A., Ferdowsi M., Alijani A., Goharpey S.
Human Movement
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2008
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vol. 9
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issue 2
103-106
EN
Purpose. The purpose of this study was to investigate and compare the effects of plyometric and weight (isotonic) training on lower extremity electromyography in physical education students. Basic procedures. In this study, 45 students from the physical education and sport sciences faculty of Shahid Chamran University were selected and divided in 3 groups (plyometric - 15, weight - 15, control - 15). Two experimental groups participated in a 6 week and a 3 week period sessions. The electrical changes of muscles were measured using sergeant test for explosive power and squat test for absolute power. Main findings. The data was collected via MT8 and analyzed using MBM. The results of the variance analysis test (ANOVA) were compared with the average values of electromyography changes (explosive and absolute power) and it was shown that electrical changes (explosive and absolute power) of biceps femoris muscle in all groups were non-significant whereas electrical changes (explosive and absolute power) of rectus femoris and gastrocenimus muscles were significant.
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