Anaerobic threshold determination through ventilatory and electromyographics parameters.

The aim of present study was to compare the alterations in electromyography signs with Ventilatory Threshold (VT). Had been part of the study eight men, amateur cyclists and triathletes (25.25 +/- 6.96 years), that they had exercised themselves in a mechanical cicloergometer, a cadence of 80 RPM and with the increased intensity being in 25 W/min until the exhaustion. The VT was determined by a non-linear increase in VE/VO2 without any increase in VE/VCO2 and compared with the intensity corresponding to break point of amplitude EMG sign during the incremental exercise. The EMG--Fatigue Threshold (FT) and Ventilatory Threshold (VT) parameters used were the power, the time, absolute and relative VO2, ventilation (VE), the heart hate (HH) and the subjective perception of the effort. The results had not shown to difference in none of the variable selected for the corresponding intensity to VT and FT--EMG of the muscles lateralis vastus and femoris rectus. The parameters used in the comparison between the electromyographic indicators and ventilatory were the load, the time, absolute VO2 and relative to corporal mass, to ventilation (VE), the heart frequency (HH) and the Subjective Perception of the Effort (SPE).

Electromyography study of skeletal muscle during locomotion in a treadmill test: a case study.

Recent researches are trying to rebuild an important human history of its posture and march from the anatomic function evolutions of the skeletal muscle (10, 11, 9, 2). The aim of this study is to verify electromyography data of muscles recto femoris, iliocostalis, gluteus maximus, erector spinae, semitendinosus during human locomotion in two different treadmill protocols (Naughton and Bruce). Data analyses, such as mean was calculated on the Word Office Excel. For electromyography data Aqdata program was utilized. Muscles rectus femoris, iliocostalis, gluteus maximus, erector spinae, semitendinosus were studied using electromyography analyses during human locomotion in treadmill. A number of six individuals was selected for this research. For the Bruce test all individuals ended there participation in the test on the fourth or fifth stage. For the Naughton test all individuals completed the 21 minutes walking. For the Bruce test all the muscle had higher RMS mean when compared with Naughton test, due the effort level for each test.

Electromyographical study of the iliocostalis lumborum and gluteus maximus muscles during locomotion on a treadmill and in a ground.

The aim of this work was to study the potential action of the Iliocostalis lumborum and gluteus maximus muscles by electromyography during locomotion in a ground and on a treadmill in 10 male subjects ages 19 to 25 years old. To the locomotion in a ground, the subjects started running in a stationary place for 15 seconds and then ran 10 meters at an average speed of 6.0 mph. To locomotion on a treadmill it was also set 6.0 mph during 60 seconds. The registers presented here refer to the last 5 seconds to treadmill test and during the first 5 seconds to test in a ground. A LYNX- AI 6010 electromyography containing 6 channels was used for this study. It was established a frequency of 1200 Hz to acquire the electromyography's registers, being the low pass filter 600 Hz and the high pass filter 10 Hz. The configuration of the entrance limits of the signals was established at 2000 microV (high limit) and -2000 (low limit)microV for both muscles on a treadmill and in a ground. The results of the muscular potential actions presented in RMS were greater on a treadmill for both muscles, with the predominance of the gluteus maximus muscles when it was compared in a ground. When they were compared between them, the gluteus maximus muscle was more active than the Iliocostalis lumborum muscle.

EMG study of the pectoralis major (sternal portion), teres major, latissimus dorsi and deltoid medial muscles in volleyball players.

UNLABELLED: The pectoralis major (sternal portion), teres major, latissimus dorsi and deltoid medial muscles has been studied through in the electromyography in 8 male individuals, who practice volleyball, youth category, (age between 15 and 17 (average 16.25), right-handed, involved in volleyball for about one year. The objective was to analyze the potential of action of these muscles engaged in the volleyball movements: service, spike, pass, set and blocking with and without ball. The work was developed in the laboratory of Electromyography and Biomechanics of Posture (Physical Education Faculty - State University of Campinas - UNICAMP). To caption the muscles action potential, surface electrodes were set with conductive gel and fixed on the skin, in the center of the muscles. It was used an electromyography Lynx with 6 channels. The apparatus calibration was 3000 microV; 1199.760 Hz. The sequential experiments without ball were performed for 10 seconds, and the sequential experiments with ball in 12 seconds. RESULTS: None of the muscles presented significative difference (p > 0,05) when compared to the sequential movements executed with and without ball. When compared to the sequential movements executed without ball, the only muscles that presented significative differences (p < 0,05) were: pectoralis major / deltoid and latissimus dorsi / deltoid, for another hand when in the comparative of the movements with ball, all muscles when compared to the latissimus dorsi, presented a significance difference (p < 0,05). It is interesting to observe, that the general average and the standard deviation of the deltoid muscle (medial portion), teres major, and latis-simus dorsi were higher in the sequential movements executed without ball.

Electromyographic study of the flexor muscles of the elbow articulation in weightlifting trained subjects.

The purpose of this work was to register the electromyography data of the muscles brachialis, biceps brachii long portion, biceps brachii short portion and brachioradialis in the movements of elbow flexion, in the "Larry Scott" bench, in supination and pronation positions, in weightlifting trained subjects. Ten male right-handed subjects were selected, with at least one-year experience in weightlifting exercises, without previous neuromuscular diseases, age between 21 and 26 years. After taking the "Maximum Load" (M.L.) test, or a maximum repetition, we had the percent pattern to establish the loads used in the tests, which was 80%0 of the M. L. For the electromyography records was used a six-channel electromyography (lynx) and the AqDados software in four different moments for each subject: an isometric phase lasting five seconds in supination (1), keeping a 90 degrees angle between the arm and forearm; another one in isometric pronation (2); ten repetitions lasting fifty seconds in supination (3); and ten repetitions in pronation (4). The results of the normalization showed a level of similar activation between the involved muscles in one same moment, as much in supination as in pronation. From the analysis of variance ANOVA, having as level of significance p < 0,05, concludes that it did not have significant difference in the performance of these muscles. When compared between itself all the values of p were bigger than 0,05. Of this form we can perceive a joint action of all the flexion muscle of the elbow to resist the load imposed during the effort.

Electromyographical study of the pectoralis major (sternocostal part) and deltoid muscles (middle fibers) in volleyball sequential actions.

UNLABELLED: The Pectoralis Major muscles (Sternocostal part) and Deltoid (middle fibers) had been studied using electromyography in 8 male individuals, who practice volleyball, youth category, (age between 15 and 17 average +/- 16,25 years old), right-handed, those involved in volleyball for about one year. The objective was to analyze the potential of action of these muscles engaged in the volleyball movements: service, spike, pass, set and blocking with and without ball. The work was developed in the Electromyography and Biomechanics of Posture Laboratory(Physical Education Faculty--State University of Campinas--UNICAMP). To caption the muscle action potential, surface electrodes were set with conductive gel and fixed on the skin, in the center of the muscles. It was used an electromyography Lynx with 6 channels. The apparatus calibration was 2.500 microV, 1199.760 Hz. The low and high pass filter was set at 600-10 Hz. The sequential experiments without ball were performed for 10 seconds, and the sequential experiments with ball in 12 seconds. RESULTS: The Pectoralis Major muscle (Sternocostal part) revealed active during the basic movements of volleyball, (service and spike) in all movements of the extension of the arm, as well as the arm abduction during the pass movement. The Deltoid muscle (middle fibers), in spite of being primary in the abduction, showed the potential of action in all movements practiced in volleyball, however, they were more intense, in the spike and block actions. It is interesting to observe, that the general average and the standard deviation of the Deltoid muscle (middle fibers), were higher in the sequential movements executed without ball.

Electromyography in cycling: difference between clipless pedal and toe clip pedal.

The purpose of this study was to verify if there is electromyographic difference in biceps femoris (long portion), semitendinous, semimembranous and gastrocnemius (lateralis and medialis) muscles, using clipless pedal and toe clip pedal. Thirty seven triathletes answered a questionnaire about their preferred type of pedal, which showed that 5.4% used toe clip pedal and 94.6% used clipless pedal. Four male triathletes (age: 21.75 +/- 2.50 years old; cycling experience: 5.00 +/- 2.45 years; preferred cadence: 83.75 +/- 7.5 rpm) rode their own bicycles on a stationary roller at 100 rpm. The subjects performed one trial with each type of pedal. Bipolar surface electrodes placed on right lower limb picked up the EMG signal during 6 s. A band-pass filter (10-600 Hz) was used. Two muscles (semitendinous and semimembranous) presented lower activity with clipless pedal for all subjects. Biceps femoris and gastrocnemius lateralis presented lower activity with clipless pedal for three subjects. This led us to conclude that there is less electromyographic activity with the use of clipless pedal.

Electromyography response of the iliocostalis lumborum muscle during flexion, extension and rotation movements of the trunk in orthostatic and seated position.

The action of the column extensor muscles has been studied through in the electromyography in various corporal postures. We verified the electromyography responses of the iliocostalis lumborum muscle during various movements and positions. 12 individuals males, sedentary, between 36 and 52 years old (average 46.16), weighing an average of 79.66 kilos, and with an average height of 173.0 cm, all working as drivers were studied. Electromyography with six channels and surface electrodes was used. The electrodes were placed on the right side of the trunk in the direction of the third and fifth lumbar vertebrae ICL2 and ICL1 respectively). In orthostatic position, the flexion movement presented RMS 31.18 (+/- 5.73) in ICL1 and 58.10 (+/- 14.81) in ICL2; in extension the RMS 32.46 (+/- 9.17) in ICL1 and 55.31 (+/- 16.70) in ICL2; in homolateral rotation the RMS 30.05 (+/- 10.60) in ICL1 and 53.29 (+/- 19.70) in ICL2; in heterolateral rotation the RMS 24.76 (+/- 5.99) in ICL1 and 44.79 (+/- 15.26) in ICL2. In seated in a chair without a back, the flexion presented RMS 22.42 (+/- 2.89) in ICL1 and 43.39 (+/- 5.68) in ICL2; in extension the RMS 22.47 (+/- 1.95) in ICL1 and 41.28 (+/- 6.20) in ICL2; in homolateral rotation the RMS 24.10 (+/- 3.97) in ICL1 and 47.94 (+/- 5.80) in ICL2; in heterolateral rotation, the RMS 22.59 (+/- 1.95) in ICL1 and 43.15 (+/- 5.71) in ICL2. In the position seated on the ground, the flexion presented RMS 22.83 (+/- 3.00) in ICL1 and 50.99 (+/- 11.19) in ICL2; in extension the RMS 22.39 (+/- 3.22) in ICL1 and 46.44 (+/- 8.19) in ICL2. The results are expressed in RMS, indicating the participation of the iliocostalis lumborum muscle during the movements undertaken. The place identified as ICL2 presented action potential of greater amplitude than the place identified as ICL1 in all movements and positions.

Electromyography study of the hamstring muscles while exercising on a bicycle and the Roman table.

During the past few years electromyography has been used a lot in developing research in the science of sports; it has made a great contribution to what is called muscle biomechanics. The Biceps Femoris (long head), Semitendinosus and Semimembranosus bi-articulated muscles make up the muscle group called Hamstring; they act in articulated movements of the hip (extensors) and in articulated movement of the knee (flexors). In this sense, the Hamstring have been the object of many investigations, precisely because they are bi-articulated. All the Hamstring pass through the knee's articulation producing flexing as well as leg rotation and their effectiveness as hip extensors depends on the positioning of the knee's articulation, Hamill, Knutzen (1999). The knee's flexor muscles (Biceps Femoris - long head, Semimembranosus and Semitendinosus) were studied using electromyography with surface electrodes in 10 male subjects between 19 and 25 years old. They included five who used a stationary bicycle and five doing activities on the roman table. Knee flexing on the roman table (concentric and eccentric action) was performed in the ventral decubitus position. Surface electrodes with electro-conductive gel were used to register the action potentials; they we fixed on the skin covering the areas of interest to this study in each ventral muscle. For each type of experiment, a laboratory with all the apparatus needed for the study was created. Results, expressed in RMS, demonstrate that on the bicycle the Biceps Femoris (long head) showed an RMS of 31.81 (+/- 10.15), the Semimembranosus 65.15 (+/- 18.76) and the Semitendinosus 44.33 (+/- 44.33 (+/- 22.34). In flexing the knee the values were 188.54 (+/- 46.10) for the Biceps Femoris (long head) muscle, 480.00 (+/- 130.13) for the Semimembranosus and 303.50 (+/- 63.31) for the Semitendinosus. The verified data demonstrated greater values for the bicycle activities. The Semimembranosus muscle showed greater values in RMS for all activities studied, followed by the Semitendinosus and Biceps Femoris (long head).

Analysis of knee movements on leg extension machine: an electromyography study of the rectus femoris muscle.

The Rectus Femoris muscle was analyzed by electromyography in 10 female subjects between 19 and 22 years old. Surface electrodes were utilized by placing them at the middle of the muscle. The course of the flexing/extending movements of the knee were analyzed on a Leg Extension Machine. The results showed that the MIC value was greater in the series with loads than in the series without loads. For the Maximum Isometric Contraction (MIC) the value was 144.00. In the movement executed without load the value was 73.96. In the first series with the initial 15 Kg load the value was 163.7 and in the last series of the initial load the value was 194.9. With the 19 Kg load in the first series the value was 182.5 and in the last series the value was 205.1. In the first series with the 21 Kg load the value was 165.1 and in the last series with the 21 Kg load the value was 23.09. The values reflecting the need to recruit more muscle fibers to continue executing the movement. The value 23.09 shows the difficulty in proceeding with the movements and can be considered the beginning of a muscular fatigue process in the Rectus Femoris muscle.

Electromyographical study of the iliocostalis lumborum, longissimus thoracis and spinalis thoracis muscles in various positions and movements.

The iliocostalis lumborum, longissimus thoracis and spinalis thoracis muscles were studied electromyographically in six male individuals between 18 and 23 years old. They were connected to co-axial needle electrodes while in orthostatic, kneeling and sitting positions performing movements of flexing, extending and rotating the trunk. In the total flexing of the trunk the muscles did not present any action potential. The results showed intense potential for action while flexing the trunk 45 degrees, extending the trunk beginning at 45 degrees of flexing and in homolateral rotation for the muscles analyzed in the orthostatic position, emphasizing the iliocostalis lumborum muscle in the extension of the trunk which registered very strong action potentials in all individuals. There were similar results for movements of flexing and extending the trunk in the kneeling position, emphasizing the longissimus thoracis muscle in the movement of hyperextension. In the sitting position the more intense potentials were for the movements of extension, flexing with rotation and homolateral rotation of the trunk, emphasizing the longissimus thoracis muscle with strong potentials.

Study of the explosive strength of the rectus femoris muscle using electromyography.

The rectus femoris muscle was electromyographically studied in eleven individuals of the masculine sex. The objective was to study the action potential and the explosive strength of this particular muscle in the movement utilized to kick the field soccer ball and in other exercises of the orthostatic position. The following movements were analyzed: flexibility of the hip with the knee bent, flexibility and extension of the knee (completely crouched), flexibility of the hip with the knee extended, movement of the kick without contact with the ball and movement of the kick in contact with the ball. The results were: the rectus femoris muscle showed much stronger action potential in flexing the hip with the knee flexed more than 90 degrees; with the knee extended 60 to 90 degrees; in the movement extending the knee from a complete crouch and at the moment of the kick in contact with the ball. The action potential was strong in the movements flexing the knee (crouch) and in the initial movement of the kick.

Electromyography analysis of the rectus abdominis and external oblique muscles of children 8 to 10 years old.

The objective of this work was to study through in the electromyography the upper and lower umbilical rectus abdominis and the anterior and posterior parts of the external oblique muscles of children 8 to 10 years old. The children studied practice artistic and rhythmical gymnastic sports at the training and learning level and the study was made during abdominal exercise in the dorsal decubitus position on the ground and on a board. The children were divided into 2 groups: Group I - ten already trained children; Group II - nineteen learners. The participants in Group I practiced an average of 5 times a week and those in Group II practiced 2 times a week. The exercises analyzed were: on the ground, lifting the legs 30, 20 and 10 cm high with the knees flexed 90 degrees; flexing the trunk while maintaining the legs elevated and the knees flexed; flexing the trunk with homo and heterolateral rotation of the trunk while maintaining the legs elevated and the knees flexed. On the board, flexing the trunk with the knees flexed 90 degrees on top of the board inclined 30, 20 and 10 cm; flexing the trunk with rotation of the trunk homo and heterolateral with the knees flexed on the board inclined 30, 20 and 10 cm. The results showed that the superior umbilical part of the rectus abdominis muscle presented more intense action potential than the inferior-umbilical part; the more intense action potential occurred at the flexing of the trunk and at the flexing of the trunk with homo and heterolateral rotation. The anterior part of the external oblique muscle presented more intense action potential than the posterior part; the more intense action potential occurred at the flexing of the trunk and at the flexing of the trunk with heterolateral rotation. In both of the muscles the more intense action potential occurred between 45 and 60 degrees of flexing the trunk; the children in Group I presented more intense action potential than those in Group II; the exercise of lifting the flexed legs did not prove efficient for strengthening the analyzed abdominal muscle structure.

Using weights in abdominal exercises: electromyography response of the Rectus Abdominis and Rectus Femoris muscles.

Among persons who do regular exercises, many include abdominal exercises in their customary routine. For this, there are a growing variety of movements being created for strengthening the abdominal muscles. This work aims to know, through electromyography analysis, the action potencies of the supra and infra umbilical of the Rectus Abdominis and Rectus Femoris muscles during the execution of abdominal exercises with and without the addition of weights. Lying on the backside, seven flexing movements of the trunk--one without weight, three with 2 Kg on the neck, elbow and chest and three with 4 Kg on the same points--were executed. Nine female university students between 18 and 23 years old participated in the study. Surface electrodes were fixed to the supra and infra umbilical areas of the Rectus Abdominis and Rectus Femoris muscles. The results showed that the utilization of weights in the abdominal exercises did not appear to be effective for the Rectus Abdominis muscle since greater action potencies were only verified in the Rectus Femoris muscle. We concluded that the differences observed in the RMS were not relevant to the point of indicating the utilization of weights to improve abdominal exercises because greater action potencies were only observed in the Rectus Femoris muscle.

Análise eletromiográfica do músculo reto femoral durante a execução de movimentos do joelho na mesa extensora / Electromyographic analysis of the rectus femoris muscle during the execution of movements of the knee in leg extension machine

O músculo reto femoral foi analisado por meio da eletromiografia, utilizando eletrodos de superfície, durante os movimentos de flexão e extensão do joelho. Participaram do estudo dez sujeitos do sexo feminino, na faixa etária entre 19 e 22 anos. Inicialmente, foi realizada uma máxima contração isométrica (MCI). Posteriormente, realizou-se uma série de 12 repetições sem carga (SC); 12 séries de 12 repetições com diferentes cargas (15, 17, 19 e 21 kg). Para este trabalho selecionamos os dados referentes à MCI, movimentos sem cargas, movimento com 15 Kg, com 19 Kg e 21Kg. Os valores médios, expressos em RMS, demonstraram que na MCI o RMS foi de 139,55; no movimento realizado sem carga foi de 51,54; na carga de 15 kg foi de 134,65; na carga de 19 Kg foi de 136,54 e com 21Kg o RMS foi de 10,09. Os valores de RMS obtidos no movimento SC e com 21 kg foram inferiores aos encontrados nas condições MCI, 15 kg e 19 kg. O valor de 10,09 referente à carga de 21 Kg reflete a dificuldade em prosseguir a execução dos movimentos, podendo ser considerado o início do processo de fadiga muscular do músculo reto femoral.

The rectus femoral muscle was analyzed by electromyography, in 10 female subjects between 19 and 22 years old, during the flexing/extending movements of the knee. Surface electrodes were utilized. Initially a maximum isometric contraction (MIC) was performed. Afterwards, a series of 12 repetitions without load, and then 12 series of 12 repetitions with different loads (15, 17, 19, and 21kg) were performed. For this study, we chose data referring to the MCI, the movements without load, and those with 15kg, 19kg, and 21kg loads. The average values, expressed in RMS, were: for the Maximum Isometric Contraction (MIC), 136.55; for the movements executed without load, 51. 54; for the first series with the initial 15kg load, 134.65; for that with the 19kg load, 136.54; and for the last series with the 21kg load, 10.09. RMS values obtained from the movements without load and those with the 21kg load, reflects the difficulty in proceeding with the execution of movements and can be considered the beginning of the muscular fatigue process of the rectus femoral muscle.

Influência dos hormônios testiculares sobre a regeneraçâo óssea em fraturas da tíbia de ratos / Influence of testicular hormones over bone regeneration in rats tibial fractures

Foram estudados 32 ratos machos Wistar, com aproximadamente 120 dias, pesando em média 280 gramas. Os animais foram divididos em dois grupos (grupo controle e grupo submetido a orquiectomia) de 16 ratos cada um, e cada rato foi mantido em gaiola individual, durante toda a experiência. O trabalho foi desenvolvido em 3 etapas distintas 1ª etapa: Os animais do grupo controle, foram mantidos em condiçöes normais de um biotério, sem restriçöes. Os animais do grupo submetido a orquiectomia, foram anestesiados com éter etilico por inalaçäo, e posteriormente submetidos a orquiectomia bilateral através de uma incisäo longitudinal mediana na bolsa escrotal 2ª etapa: Os animais petencentes à ambos os grupos foram anestesiados com éter etílico por inalaçäo e submetidos a fratura na porçäo média da diáfise tibial. Os animais pertencentes ao grupo orquiectomizados foram submetidos à 2ª etapa trinta dias após a primeira cirúrgia (orquiectomia). 3ª etapa: Metade dos animais de ambos os grupos, após o 8§ dia e a outra metade após o 12§ da fratura, foram sacrificados e a tibia fraturada foi retirada. Após a remoçäo estas foram fixadas em formol a 10% durante 48 horas, em seguida foram colocadas no descalcificados (E.D.T.A. 10%), onde permaneceram 45 dias. Após a descalcificaçäo as peças foram incluidas em parafina, cortadas numa espessura de 7 micrômetros e os cortes corados pela Hematoxilina Eosina. Observando as lâminas, montadas pelos métodos histológicos convencionais, verificamos que: 1§ o calo ósseo consequente à fratura dos animais orquiectomizados, era constituído de fibrocartilagem, e dos animais näo orquiectomizados, era constituído por cartilagem calcificada apresentando regiöes osteogênicas; 2§ o periósteo e o endosteo parecem participar ativamente no processo de regeneraçäo do tecido ósseo; 3§ o processo de ossificaçäo foi mais intenso e mais acentuado em animais näo orquiectomizados. 4§ Portanto, houve diferença acentuada no processo de fraturar entre os animais dos dois grupos; em decorrencia disto talvez possamos sugerir que, os hormonios testiculares agem diretamento sobre o tecido ósseo em relaçäo a síntese da matriz orgânica