Práce se zabývá popisem postavení předloktí při manipulaci s různými typy počítačových myší během práce u počítače. Cílem studie bylo porovnat aktivitu vybraných svalů horní končetiny pomocí povrchové elektromyografie při práci u počítače vsedě s klasickou a vertikální počítačovou myší. Do výzkumu bylo zahrnuto 8 probandů (věk 43,1 ± 7,8 let, práce u počítače 8,6 ± 1,4 hodin denně), kteří neměli dřívější zkušenost s vertikální počítačovou myší. Pro hodnocení svalové aktivity vybraných svalů horní končetiny byl využit přístroj pro povrchovou elektromyografii TeleMyo 2400T G2 s programem MyoResearch verze 3 (NORAXON, USA Inc., Scottsdale, Arizona). Měřeny byly tyto svaly (musculi): extenzor carpi radialis longus, flexor carpi radialis, triceps brachii – caput laterale a caput longum, biceps brachii – společné svalové bříško, deltoideus – pars anterior, pars acromialis a pars posterior, trapezius – pars superior, pars medialis, pars inferior. U všech probandů proběhla dvě měření se stejnými dopředu stanovenými úkony. První měření probíhalo za užití klasické myši. Poté byla probandům předána vertikální počítačová myš HE-Mouse (R-Go Tools B.V., Nizozemí) s instruktáži, jak s ní manipulovat. Po devíti měsících užívání vertikální počítačové myši následovalo druhé měření. Použitím vertikální počítačové myši došlo k významnému snížení aktivity m. trapezius pars inferior a m. flexor carpi radialis v porovnání s klasickou počítačovou myší. Semipronační postavení předloktí podpořilo centraci ramenního kloubu a relaxaci ruky v porovnání s pronačním nastavením předloktí u klasické počítačové myši. Vertikální počítačová myš se u sledované skupiny probandů jeví jako vhodná volba pro eliminaci muskuloskeletálních potíží v oblasti pletence HK, předloktí a zápěstí.
The work deals with the description of the position of the forearm when handling different types of computer mice while working at the computer. The aim of the study was to compare the activity of selected muscles of the upper limb using surface electromyography during working at a computer while sitting with a classic and vertical computer mouse. 8 probands (age 43.1 ± 7.8 years, working at a computer 8.6 ± 1.4 hours per day) who had no previous experience with a vertical computer mouse were included in the research. A TeleMyo2400TG2 surface electromyography device with the MyoResearch version 3 program (NORAXON, USA Inc., Scottsdale, Arizona) was used to evaluate the muscle activity of selected muscles of the upper limb. The following muscles were measured (musculi): extensor carpi radialis longus, flexor carpi radialis, triceps brachii – caput laterale and caput longum, biceps brachii – common muscle belly, deltoideus – pars anterior, pars acromialis and pars posterior, trapezius – pars superior, pars medialis, pars inferior. All probands underwent two measurements with the same predetermined actions. The first measurement took place using a classic mouse. Afterwards, the probands were given HE-Mouse vertical computer mouse (R-Go Tools B.V., The Netherlands) with instructions on how to handle it. After nine months of using the vertical computer mouse, a second measurement followed. By using the vertical computer mouse there was a significant reduction of the trapezius pars inferior muscle and the flexor carpi radialis muscle compared to a classic computer mouse. The semi-pronated position of the forearm supported the centering of the shoulder joint and the relaxation of the hand compared to the pronated position of the forearm in a classic computer mouse. The vertical computer mouse appears to be a suitable choice for the elimination of musculoskeletal problems in the upper limb girdle area forearm and wrist for the group of probands under investigation.
The aim of this study was to explore the effects of simulated soccer match play on neuromuscular performance in adolescent players longitudinally over a two-year period. Eleven players completed all measurements in both years of the study (1st year: age 16.0 ± 0.4 y; stature 178.8 ± 6.4 cm; mass 67.5 ± 7.8 kg; maturity-offset 2.24 ± 0.71 y). There was a significant reduction in hamstring strength after simulated match by the soccer-specific aerobic field test (SAFT90), with four out of eight parameters compromised in U16s (4.7-7.8% decrease) and six in the U17s (3.1-15.4%). In the U17s all of the concentric quadriceps strength parameters were decreased (3.7-8.6%) as well as the vastus lateralis and semitendinosus firing frequency (26.9-35.4%). In both ages leg stiffness decreased (9.2-10.2%) and reactive strength increased pre to post simulated match (U16 8.0%; U17 2.5%). A comparison of changes between age groups did not show any differences. This study demonstrates a decrease in neuromuscular performance post simulated match play in both ages but observed changes were not age dependent.
Poor neuromuscular control and fatigue have been proposed as a risk factor for non-contact injuries especially around peak height velocity (PHV). This study explored the effects of competitive soccer match-play on neuromuscular performance and muscle damage in male youth soccer players. 24 youth players aged 13-16y were split into a PHV group (-0.5 to 0.5y) and post PHV group (1.0-2.5y) based on maturity off-set. Leg stiffness, reactive strength index (RSI), muscle activation, creatine kinase (CK), and muscle soreness were determined pre and post a competitive soccer match. Paired t-tests were used to explore differences pre and post competitive match play and independent sample t-tests for between groups differences for all outcome measures. There was no significant fatigue-related change in absolute and relative leg stiffness or muscle activation in both groups, except for the gastrocnemius in the post PHV group. RSI, CK and perceived muscle soreness were significantly different after soccer match-play in both groups with small to large effects observed (ES:0.41-2.82). There were no significant differences between the groups pre match-play except for absolute and relative leg stiffness (P < 0.001; ES = 1.16 and 0.63 respectively). No significant differences were observed in the fatigue related responses to competitive match play between groups except for perceived muscle soreness. The influence of competitive match-play on neuromuscular function and muscle damage is similar in male youth around the time of PHV and those post-PHV indicating that other factors must contribute to the heightened injury risk around PHV.
- MeSH
- fotbal * MeSH
- kompetitivní chování MeSH
- kosterní svaly patofyziologie MeSH
- kreatinkinasa krev MeSH
- lidé MeSH
- mladiství MeSH
- myalgie patofyziologie MeSH
- sport pro děti a mládež MeSH
- sportovní výkon * MeSH
- svalová únava * MeSH
- věkové faktory MeSH
- Check Tag
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
The aim of this study was to examine the acute effects of soccer specific fatigue on muscular and neuromuscular function in male youth soccer players. Elite soccer players (n = 20; age 15.7 ± 0.5 y; body height 177.75 ± 6.61 cm; body mass 67.28 ± 8.29 kg) were measured before and after soccer specific exercise (SAFT90). The reactive strength index (RSI) was determined by a drop jump test, leg stiffness (LS) by a 20 sub-maximal two-legged hopping test, and a functional hamstring to quadriceps strength ratio from isokinetic concentric and eccentric strength of the dominant and non-dominant leg (measured at angular velocities of 1.05 rad · s-1 and 3.14 rad · s-1). Metabolic response to the SAFT90 was determined by blood lactate and perceived exertion was assessed by the Borg scale. After simulated match play, a significant decrease in absolute LS (t = 4.411; p < 0.001; ω2 = 0.48) and relative LS (t = 4.326; p < 0.001; ω2 = 0.49) was observed and the RSI increased significantly (t = 3.806; p = 0.001; ω2 = 0.40). A reduction in LS found after the SAFT90 indicates possible reduction in dynamic knee stabilization. However, if we consider the changes in other observed variables, the present study did not clearly confirm that fatigue induced by a soccer specific protocol increased the risk of ACL and hamstring injury. This may be attributed to the simulated rather than actual match play used in the present study.
- Publikační typ
- časopisecké články MeSH
- MeSH
- bederní obratle fyziologie patofyziologie MeSH
- lidé MeSH
- mladiství MeSH
- raketové sporty MeSH
- rozsah kloubních pohybů MeSH
- sportovní úrazy prevence a kontrola MeSH
- strečink metody MeSH
- terapie cvičením metody metody MeSH
- zádové svalstvo fyziologie patofyziologie MeSH
- Check Tag
- lidé MeSH
- mladiství MeSH
Poor neuromuscular control has been proposed as a risk factor for non-contact injuries, thus this study aimed to explore the effects of soccer-specific fatigue on leg muscle activation, reactive strength, leg stiffness, and functional hamstring/quadriceps ratio (H/QFUNC ) in elite male youth soccer players. Outcome measures were determined in 18 youth players (age 14.4 ± 0.5 years; stature 169.4 ± 9.9 cm; mass 59.3 ± 8.9 kg; maturity offset 0.86 ± 0.88 years) pre and post simulated soccer match play (SAFT90 ). There was no fatigue-related change in the H/QFUNC ; however, reactive strength and leg stiffness were both compromised (P < 0.001) after soccer-specific fatigue. Muscle activation was also locally compromised (P < 0.001) in the medial hamstring and quadriceps but not in the lateral muscles. Where statistically significant changes were observed, the effect sizes ranged from small to large (0.33-0.97). Compromised stiffness when fatigue is present suggests an increased yielding action, greater ground contact times, greater center of mass displacement, and less efficient movement when the limb comes into contact with the ground. This combined with a reduction in medial quadriceps muscle activation may reflect poor kinetic chain control at the hip and an increase in knee injury risk.
- MeSH
- čtyřhlavý sval stehenní fyziologie MeSH
- cvičení * MeSH
- fotbal fyziologie MeSH
- lidé MeSH
- mladiství MeSH
- poranění kolena patofyziologie MeSH
- rizikové faktory MeSH
- sportovní úrazy patofyziologie MeSH
- svalová únava fyziologie MeSH
- Check Tag
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
The forward walking lunge (WL) and split squat (SSq) are similar exercises that have differences in the eccentric phase, and both can be performed in the ipsilateral or contralateral carrying conditions. This study aimed to determine the effects of dumbbell-carrying position on the kinematics and electromyographic (EMG) amplitudes of the gluteus medius (Gmed), vastus medialis (VM), vastus lateralis (VL), and biceps femoris during WLs and SSqs. The resistance-trained (RT) and the non-resistance-trained (NT) groups (both n = 14) performed ipsilateral WLs, contralateral WLs, ipsilateral SSqs, and contralateral SSqs in a randomized order in a simulated training session. The EMG amplitude, expressed as a percentage of the maximal voluntary isometric contraction (%MVIC), and the kinematics, expressed as the range of motion (ROM) of the hip and knee, were measured during 5 repetition maximum for both legs. The repeated measure analyses of variance showed significant differences between the RT and NT groups. The NT group showed a smaller knee flexion ROM (p < 0.001, η = 0.36) during both types of WLs, whereas the RT group showed a higher eccentric Gmed amplitude (p < 0.001, η = 0.46) during all exercises and a higher eccentric VL amplitude (p < 0.001, η = 0.63) during contralateral WLs. Further differences were found between contralateral and ipsilateral WLs in both the RT (p < 0.001, η = 0.69) and NT groups (p < 0.001, η = 0.80), and contralateral WLs resulted in higher eccentric Gmed amplitudes. Contralateral WLs highly activated the Gmed (90% MVIC); therefore, this exercise can increase the Gmed maximal strength. The ipsilateral loading condition did not increase the Gmed or VM activity in the RT or NT group.
- MeSH
- biomechanika fyziologie MeSH
- chůze fyziologie MeSH
- dolní končetina fyziologie MeSH
- dospělí MeSH
- elektromyografie * MeSH
- isometrická kontrakce fyziologie MeSH
- kosterní svaly fyziologie MeSH
- lidé MeSH
- mladý dospělý MeSH
- odporový trénink * MeSH
- průřezové studie MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mladý dospělý MeSH
- mužské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
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.
- Publikační typ
- časopisecké články MeSH
Článek poukazuje na některá základní doporučení pro aplikaci povrchové elektromyografie v rehabilitačním výzkumu a praxi. Upozorňuje na úskalí spojená se snímáním, zpracováním, hodnocením a interpretací elektromyografického signálu. Podnětem pro vznik tohoto článku jsou některé dříve publikované články v časopisu Rehabilitace a fyzikální lékařství.
The article refers to a few basic recommendations for the use of surface electromyography in rehabilitation research and practice. It indicates difficulties associated with detection, processing, assessment and interpretation of electromyographic signal. This article is the reaction to articles published in journal the Rehabilitation and Physical Therapy (Rehabilitace a fyzikální lékařství in the Czech language).
This study compares the electromyographic (EMG) peak amplitude changes of gluteus medius (Gmed), vastus medialis (VMO), vastus lateralis (VL) and biceps femoris (BF) during load carrying walking due to the increased load. The percentage of maximum isometric voluntary contractions (%MVIC) of both limbs and 3D kinematic of lower limbs were detected on eighteen resistance-trained men (mean age ± SD, 31 ± 3.4 years) while carrying loads of 25, 50 and 75% of their body mass (BM). The repeated measurement ANOVA was used to evaluate the differences in muscles %MVIC and 3D kinematics at all load conditions. Significant differences were found for Gmed %MVIC (F3,99 = 19.8, p < 0.001). Gmed activity was significantly different between load carrying walking with 25% of BM (mean ± SD, 20 ± 12%MVIC), 50% of BM (32 ± 17%MVIC) and 75% of BM (45 ± 26%MVIC) condition. Differences were found in hip flexion at Gmed EMG peak (F3,96 = 14, p < 0.001), between 25% of BM (18 ± 11°) and 50% of BM (29 ± 7°). No significant differences were found for thigh muscles, when thigh muscle activity did not exceed 30%MVIC even at 75% of BM condition. Load carrying walking is an exercise which activates Gmed more than thigh muscles. This exercise increases the Gmed activity along with increased loads and it should be regarded as a complex Gmed strengthening exercise. This exercise is recommended for strengthening the Gmed with low activation of VL and VMO.
- MeSH
- biomechanika MeSH
- chůze * fyziologie MeSH
- dospělí MeSH
- elektromyografie * MeSH
- hýždě MeSH
- isometrická kontrakce fyziologie MeSH
- kosterní svaly * MeSH
- lidé MeSH
- stehno MeSH
- svalová kontrakce MeSH
- zatížení muskuloskeletálního systému * MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- mužské pohlaví MeSH
- Publikační typ
- práce podpořená grantem MeSH
