Relevant Muscle Groups Research Articles

Comparison of resistance training using barbell half squats and trap bar deadlifts on maximal strength, power performance, and lean mass in recreationally active females: an eight-week randomised trial

BackgroundThe aim of this study was to investigate the effect of high load resistance training using barbell half squats compared with trap bar deadlifts on maximal strength, power performance, and lean mass in recreationally active females.MethodsTwenty-two recreationally active female participants (age: 26.9 ± 7.7 yrs.; height: 166.0 ± 5.1 cm; weight: 68.6 ± 9.9 kg) were randomly assigned to either a barbell half squat group (SG: n = 10) or trap bar deadlift group (DG: n = 12). Training consisted of twice-weekly sessions for eight weeks. Both groups completed one-repetition maximum (1RM) testing for both barbell half squat and trap bar deadlift groups. Countermovement jump (CMJ) and sprint performance were also assessed. Total body (TBLM) and leg lean mass (LLM) were measured with dual-energy x-ray absorptiometry. Between-group differences were analysed using analysis of covariance.ResultsSG tended to improve 1RM half squat (21.0 ± 11.5 kg vs. 13.1 ± 7.5 kg) more than DG (mean difference (MD): 8.0 kg, 95% CI: -0.36 – 16.3 kg). A similar pattern in favour of DG (18.4 ± 11.2 vs. 11.7 ± 8.1 kg) compared to SG was observed (MD: 6.5 kg, 95% CI: -2.5 – 15.6 kg). No between-group differences for sprint, jump or lean body mass changes was observed. For groups combined, the following changes in CMJ (2.0 ± 2.4 cm), 5-m sprint (-0.020 ± 0.039 s), 15-m sprint (-0.055 ± 0.230 s), TBLM (0.84 ± 1.12 kg), and LLM (0.27 ± 0.59 kg) was observed.ConclusionsAn exercise intervention consisting of half squats or trap bar deadlift were associated with improved muscle strength, power, and lean mass. Our findings suggests that in recreationally active females, exercise selection is less of a concern provided that heavy loads are applied, and relevant muscle groups are targeted.

Modern Power Problems Training of Military Officers of Special Purpose Units

Topicality. The growing requirements for the level of functional capabilities of the body of servicemen of special purpose units require scientists, together with specialists from the Armed Forces of Ukraine, to develop effective mechanisms for improving the system of military training. The Goal of the Work. Studying the problem of the feasibility of implementing the results of modern research on adaptive changes in the body in the conditions of different load regimes into the process of military training of military personnel of special purpose units. Research Methods. The work uses a theoretical analysis and generalization of scientific literature and a sociological survey method. 25 physical training instructors in the Armed Forces and 84 servicemen of special purpose units (SPUs) took part in the study. The key issues were related to military training in the Armed Forces. A comparative analysis of the answers of instructors and servicemen with the results of research by leading scientists studying modern mechanisms for improving power capabilities was carried out. Research Results. It was established that the results of the survey of physical training instructors in the Armed Forces and military personnel of the Ukrainian Armed Forces in matters related to the use of control methods for adaptive changes in the body and load correction mechanisms do not fully correspond to the data presented by modern, mostly foreign scientists. Thus, in the modern system of force training of foreign armies, physiological, morphofunctional and biochemical methods of controlling adaptive changes in the body are actively used, and in the Armed Forces of Ukraine, as the results of our survey showed, only the heart rate indicator. Also, the Armed Forces do not use methods of quantitative assessment of force load parameters, which does not allow for the development of optimal load regimes for each category of servicemen. Conclusions. On the basis of the conducted research, it can be stated that the instructors and servicemen of the PSP who participated in the survey only minimally realize the potential that can be obtained in the process of military training. The absence of a mechanism for developing optimal load modes, their correction, and integral control of adaptive changes in the body will not allow to selectively increase the maximum strength or strength endurance indicators of the relevant muscle groups necessary for the implementation of combat tasks in a short period of time.

Nerve Transfer To Restore Pinch And Grasp For Patients With Tetraplegia

<h3>Research Objectives</h3> To evaluate the efficacy of supinator to anterior interosseous (AIN) transfers for pinch and grasp reconstruction in patients with tetraplegia. Popularization of nerve transfers has increased reconstructive options available to patients with tetraplegia. Outcomes of supinator to posterior interosseous nerve transfers in this patient population have been documented, as well as a variety of other options for restoration of AIN function. However, outcomes of supinator to AIN transfers reconstruction have not been published. <h3>Design</h3> A retrospective review of all patients who received supinator to AIN transfers at our institution with at least one year follow-up was performed. <h3>Setting</h3> This study was performed at a tertiary referral center. <h3>Participants</h3> Ten patients were identified, and four were excluded for inadequate follow-up time. Data for the remaining six patients (seven limbs) was reviewed. <h3>Interventions</h3> Not applicable. <h3>Main Outcome Measures</h3> Charts were reviewed for pre- and post-operative physical exam findings, intraoperative response to nerve stimulation, and complications. The physical exams included Medical Research Council (MRC) manual muscle testing of relevant muscle groups. An MRC grade of 3 or higher was considered a successful outcome. <h3>Results</h3> Of the six patients (seven limbs), six had successful outcomes with MRC grade 3-4 flexor digitorum profundus and/or flexor pollicis longus function. One patient had weaker return of pinch compared to grasp. One patient reported decreased sensation to light touch at the tip of the thumb after surgery. No other donor site deficits or complications were noted. <h3>Conclusions</h3> Six of seven limbs in this cohort regained AIN function. However, one patient did not have any recovery 12 months after surgery. That patient's AIN was within the zone of injury (i.e. lower motor neuron injury), corroborated by the lack of response to stimulation intraoperatively; however, time to surgery was within an appropriate window. These findings suggest that supinator to AIN transfer is a viable option for restoration of pinch and grasp function in patients with spinal cord injury. <h3>Author(s) Disclosures</h3> None.

“When you're down, stay down”: A lesson for all competitive alpine skiers supported by an ACL rupture measured in vivo

BackgroundDuring an experiment, a ski racer equipped with various measurement devices suffered an anterior cruciate ligament (ACL) rupture in his right knee. The aim of this study was to describe the underlying injury mechanism from a functional perspective. MethodsEight giant slalom turns (i.e., 4 left turns), followed by 1 left turn at which the ACL injury occurred, were recorded by 2 video cameras, electromyography of 4 relevant muscle groups, inertial measurement units to measure knee and hip angles, and pressure insoles to determine ground reaction forces. ResultsDue to a loss of balance, the ski racer began to slide sideways at the apex of a left turn. During sliding, his right (outside) leg was actively abducted upward without touching the ground. The ski racer then attempted to stand up again by dropping his leg back towards the snow surface. The end of this dropping was accompanied by a decrease in electromyographic activity in the knee stabilizing muscles. Once the inside edge of the outer ski caught the snow surface, a rapidly increasing peak force, knee flexion, and an aggressive sudden activation of the vastus medialis muscle were observed, while biceps femoris and rectus femoris further decreased their activation levels. This likely resulted in excessive anterior translation of the tibia relative to the femur, causing damage to the ACL. ConclusionOur example emphasizes that ski racers should not get up until they stop sliding. Remember: “When you're down, stay down.”

The Characteristics of Muscle Tone and Stiffness in Young Adults with Chronic Low Back Pain

The prevalence of chronic low back pain (CLBP) in young adults is increasing; however, the biological mechanism of CLBP in this population remains unknown. PURPOSE: To observe the characteristics of muscle tone and stiffness (MTS) of relevant muscle groups in young adults with CLBP, in order to provide reference for rehabilitation and prevention of CLBP. METHODS: Twenty six subjects with CLBP (age: 22±2 years, 14 males and 12 females) were recruited as the experimental (E) group, while 29 healthy subjects (age: 25±2 years, 16 males and 13 females) were recruited as the control (C) group. The degree of pain (Visual Analogue Scale/Score, VAS) was recorded, and the MTS (indicators including F-Frequency, D-Logarithmic Decrement and S-Stiffness) of three muscle groups (para-spinal, hamstring and tensor fascia lata muscles) was assessed using the Myoton-3 equipment. Group differences were determined by using independent-sample t-tests; within the E group, MTS was compared between gender and degree of pain (VAS) using ANOVA. RESULTS:Compared with C group, the E group's MTS of all three muscles were significantly higher(p<0.05), and the differences were 11.4%, 10.0% and 14.9% respectively; E group showed bilateral imbalance in all three muscles, while C group did not show imbalance. With the E group, compared with female subjects, male subjects had higher MTS of tensor fascia lata and para-spinal muscles (p<0.05), and the differences were 12.8% and 20.0%, respectively; in addition, the MTS values of tensor fascia lata, hamstring and para-spinal muscles in the subjects with moderate pain (VAS 4-7) were higher than those with mild pain (VAS 1-3) (p<0.05), and the differences were 12.7%, 14.9% and 22.2% respectively. CONCLUSIONS: MTS is associated with considerable increase of hamstring, para-spinal muscle and tensor fascia lata in young patients with CLBP; Young CLBP patients had significant bilateral MTS imbalance of all these muscles; Young male CLBP patients had higher MTS in para-spinal muscle and tensor fascia lata than female patients; The more painful, the higher of the MTS in young CLBP patients.

Muscular imbalances and balance capability in dance

ObjectiveA high unilateral load to the musculoskeletal system is specific for formation dance. Due to the lack of data the aim of this study was the side-related (right – left) analysis of strength- and balance capability subject to injuries, gender and performance standards.MethodsN = 51 dancers (m: n = 24, f: m = 27) of two performance levels participated in this cross-sectional study. Double-sided tests of the isometric maximal strength of relevant muscle groups and the balance capability were carried out. The tests were supplemented by a self report questionnaire.ResultsTests of the isometric maximal strength in the elite performance level showed significant differences between either side of the body. As to the balance capability, no significant side-related differences could be found in. Correlations between the strength capability and the injuries could be observed in either group.ConclusionThe significant strength differences are presumably caused by the right-sided load in the dance-specific movements. The cautious conclusion that movement patterns challenge the stability of either side of the body likewise may be allowed. The increased injury frequency at the muscularly stronger side of the body primarily results from an overload. An additive muscular training should be considered as a preventive measure.

Functional muscle asymmetries and laterality in Latin American formation dancers.

Despite the high popularity of Latin American dance and the specific movement patterns characteristic of this dance discipline, studies on the physical effects of these dance style specific movement patterns are still lacking. The purpose of the present study is to analyze strength level differences and shortening of relevant muscle groups resulting from formation dance, taking performance standard and gender into consideration. Furthermore, the correlation between the findings of muscle function tests (MFT) and the occurrence of lumbar spine complaints is evaluated. A total of 66 participants (m: n= 31, f: n= 35) volunteered for this cross-sectional study (examination group, n= 39, m: n= 19, f: n= 20). The control group consisted of n= 27 participants (m: n= 12, f: n= 15). Besides isometric maximal strength tests (Digi Max system, mechaTronic), relevant muscle groups were examined for shortenings (hip flexors, hamstrings). The male participants in dance sport reached a significantly higher strength level in the muscles of the spine region (p= 0.011) than the participants of the control group. The female elite dance athletes developed a significantly higher strength level in the knee flexors on the right side than the dancers of the advanced group (NL) (p= 0.021). At that, muscle shortening were observed that seem to be specific to dance sport. In addition, gender specific differences were observed both in strength levels and in tendency to shortenings. The specific requirements profile of Latin American formation dance seems to produce affects in the form of muscular imbalance on both sides of the body. These differences of muscular status were mainly observed between dance sport competitors and non-dancers rather than between performance levels. Future investigations with higher numbers of participants would be necessary here.

Bed Rest, Exercise Countermeasure and Reconditioning Effects on the Human Resting Muscle Tone System.

The human resting muscle tone (HRMT) system provides structural and functional support to skeletal muscle and associated myofascial structures (tendons, fascia) in normal life. Little information is available on changes to the HRMT in bed rest. A set of dynamic oscillation mechanosignals ([Hz], [N/m], log decrement, [ms]) collected and computed by a hand-held digital palpation device (MyotonPRO) were used to study changes in tone and in key biomechanical and viscoelastic properties in global and postural skeletal muscle tendons and fascia from a non-exercise control (CTR) and an exercise (JUMP) group performing reactive jumps on a customized sledge system during a 60 days head-down tilt bed rest (RSL Study 2015–2016). A set of baseline and differential natural oscillation signal patterns were identified as key determinants in resting muscle and myofascial structures from back, thigh, calf, patellar and Achilles tendon, and plantar fascia. The greatest changes were found in thigh and calf muscle and tendon, with little change in the shoulder muscles. Functional tests (one leg jumps, electromyography) showed only trends in relevant leg muscle groups. Increased anti-Collagen-I immunoreactivity found in CTR soleus biopsy cryosections was absent from JUMP. Results allow for a muscle health status definition after chronic disuse in bed rest without and with countermeasure, and following reconditioning. Findings improve our understanding of structural and functional responses of the HRMT to disuse and exercise, may help to guide treatment in various clinical settings (e.g., muscle tone disorders, neuro-rehabilitation), and promote monitoring of muscle health and training status in personalized sport and space medicine.

Electromyographic analysis of relevant muscle groups during completion of computer tasks using different computer mouse positions

Background. We analyzed muscular activity for different computer mouse positions during the completion of a timed computer task and determined whether the different mouse positions could affect muscular activity, productivity and perceived fatigue. Methods. The subjects were nine healthy young men. Two mouse positions were studied: the distal position (DP), with the forearm rested on the desk; the proximal position (PP), with only the wrist rested on the desk. The subjects performed a 16-min task in each position. Surface electromyography data were recorded for the upper back and shoulder muscles. Work productivity and muscular activity were measured for each mouse position. A visual analog scale was used to assess subjective fatigue. Results. Muscular activity was higher in muscle (m.) deltoideus (posterior) for the DP, while it was significantly higher in m. inferior infraspinatus for the PP. The visual analog scale score was significantly higher and work productivity was lower in the PP. Conclusions. We found that using a mouse in the DP rather than the PP leads to less activity of the external rotators, less perceived fatigue and more productivity. This suggests that the DP is preferable to the PP for computer work involving a mouse.

Cross-disease comparison of amyotrophic lateral sclerosis and spinal muscular atrophy reveals conservation of selective vulnerability but differential neuromuscular junction pathology.

Neuromuscular junctions are primary pathological targets in the lethal motor neuron diseases spinal muscular atrophy (SMA) and amyotrophic lateral sclerosis (ALS). Synaptic pathology and denervation of target muscle fibers has been reported prior to the appearance of clinical symptoms in mouse models of both diseases, suggesting that neuromuscular junctions are highly vulnerable from the very early stages, and are a key target for therapeutic intervention. Here we examined neuromuscular pathology longitudinally in three clinically relevant muscle groups in mouse models of ALS and SMA in order to assess their relative vulnerabilities. We show for the first time that neuromuscular junctions of the extraocular muscles (responsible for the control of eye movement) were resistant to degeneration in endstage SMA mice, as well as in late symptomatic ALS mice. Tongue muscle neuromuscular junctions were also spared in both animal models. Conversely, neuromuscular junctions of the lumbrical muscles of the hind‐paw were vulnerable in both SMA and ALS, with a loss of neuronal innervation and shrinkage of motor endplates in both diseases. Thus, the pattern of selective vulnerability was conserved across these two models of motor neuron disease. However, the first evidence of neuromuscular pathology occurred at different timepoints of disease progression, with much earlier evidence of presynaptic involvement in ALS, progressing to changes on the postsynaptic side. Conversely, in SMA changes appeared concomitantly at the neuromuscular junction, suggesting that mechanisms of neuromuscular disruption are distinct in these diseases. J. Comp. Neurol. 524:1424–1442, 2016. © 2015 The Authors The Journal of Comparative Neurology Published by Wiley Periodicals, Inc.

Локальные гипертонические эффекты сосудистой нагрузки сердца при выполнении упражнений гимнастики «Пилатес»

The effects of adaptation of cardiovascular system during muscular work and after completion are characterized by a certain agreed set of indicators of central hemodynamics, vascular workload of the heart and its contractility. The coordinated changing of hemodynamics and interactions indices of heart and vessels are determined by a functional subject&amp;#180;s state and also by capacity of the work performed by the relevant muscle groups. It is shown that when performing certain exercises of gymnastics Pilates, the values of vascular resistance (under normal systolic and diastolic blood pressure) can reach values of hypertensive level (over 2000 din-c/cm5 for peripheral vascular resistance - R and over 2000 din/cm5 for elastic vascular resistance - Ea). Such values of vascular resistance, as vascular load of the heart, are obtained during a transitional process with proper voltage group of postural muscles that provide the ability to perform certain exercises Pilates. In contrast to dynamic physical exercises, for example cycling, exercises Pilates are performed in quasi-static mode. In both cases, there is the growth of elastic vascular resistance, but in dynamic mode there is a fairly dramatic decrease in peripheral resistance, and in the quasi-static regime - an increasing EA simultaneously with the increase in peripheral resistance R.

Relationship between muscle strength and front crawl swimming velocity

PurposeCompetitive performance in swimming depends on a number of factors including, among others, the development of relevant muscle groups. The aim of the study was to clarify the relationship between muscle strength and swimming velocity and the role of individual muscle groups in front crawl swimming.MethodsSixteen physical education university students participated in the study. The strength values, defined as torque produced during isometric contractions, of eight upper and lower extremity muscle groups were measured. Data were compared with participants' front crawl swim times in the 25m and 50m distances.ResultsCorrelation analysis demonstrated a relationship between muscle strength and swimming velocity. statistically significant relationships were observed between swimming velocity and the torque values of the elbow flexor and shoulder extensor muscles as well as the sum of upper extremity muscle torque values (&lt;i&gt;p&lt;/i&gt; &lt; 0.05).ConclusionsThe results indicate the need for a focus on training those muscle groups identified as having a statistically significant relationship with swimming velocity for a given distance, as the sample showed deficiencies in the strength of those muscle groups responsible for generating propulsive force in the front crawl. Additionally, the collected data can serve as a diagnostic tool in evaluating the development of muscle groups critical for swimming performance.

Exercise-Training Intervention Studies in Competitive Swimming

Competitive swimming has a long history and is currently one of the largest Olympic sports, with 16 pool events. Several aspects separate swimming from most other sports such as (i) the prone position; (ii) simultaneous use of arms and legs for propulsion; (iii) water immersion (i.e. hydrostatic pressure on thorax and controlled respiration); (iv) propulsive forces that are applied against a fluctuant element; and (v) minimal influence of equipment on performance. Competitive swimmers are suggested to have specific anthropometrical features compared with other athletes, but are nevertheless dependent on physiological adaptations to enhance their performance. Swimmers thus engage in large volumes of training in the pool and on dry land. Strength training of various forms is widely used, and the energetic systems are addressed by aerobic and anaerobic swimming training. The aim of the current review was to report results from controlled exercise training trials within competitive swimming. From a structured literature search we found 17 controlled intervention studies that covered strength or resistance training, assisted sprint swimming, arms-only training, leg-kick training, respiratory muscle training, training the energy delivery systems and combined interventions across the aforementioned categories. Nine of the included studies were randomized controlled trials. Among the included studies we found indications that heavy strength training on dry land (one to five repetitions maximum with pull-downs for three sets with maximal effort in the concentric phase) or sprint swimming with resistance towards propulsion (maximal pushing with the arms against fixed points or pulling a perforated bowl) may be efficient for enhanced performance, and may also possibly have positive effects on stroke mechanics. The largest effect size (ES) on swimming performance was found in 50 m freestyle after a dry-land strength training regimen of maximum six repetitions across three sets in relevant muscle-groups (ES 1.05), and after a regimen of resisted- and assisted-sprint training with elastic surgical tubes (ES 1.21). Secondly, several studies suggest that high training volumes do not pose any immediate advantage over lower volumes (with higher intensity) for swim performance. Overall, very few studies were eligible for the current review although the search strategy was broad and fairly liberal. The included studies predominantly involved freestyle swimming and, overall, there seems to be more questions than answers within intervention-based competitive swimming research. We believe that this review may encourage other researchers to pursue the interesting topics within the physiology of competitive swimming.

The phenomenon of twisted growth: humeral torsion in dominant arms of high performance tennis players

This manuscript is driven by the need to understand the fundamental mechanisms that cause twisted bone growth and shoulder pain in high performance tennis players. Our ultimate goal is to predict bone mass density in the humerus through computational analysis. The underlying study spans a unique four level complete analysis consisting of a high-speed video analysis, a musculoskeletal analysis, a finite element based density growth analysis and an X-ray based bone mass density analysis. For high performance tennis players, critical loads are postulated to occur during the serve. From high-speed video analyses, the serve phases of maximum external shoulder rotation and ball impact are identified as most critical loading situations for the humerus. The corresponding posts from the video analysis are reproduced with a musculoskeletal analysis tool to determine muscle attachment points, muscle force vectors and overall forces of relevant muscle groups. Collective representative muscle forces of the deltoid, latissimus dorsi, pectoralis major and triceps are then applied as external loads in a fully 3D finite element analysis. A problem specific nonlinear finite element based density analysis tool is developed to predict functional adaptation over time. The density profiles in response to the identified critical muscle forces during serve are qualitatively compared to X-ray based bone mass density analyses.

Relationships between Upper Limb Loading, Physical Findings, and Discomfort Associated with Keyboard Use

This paper presents findings of a preliminary investigation of the relationship between upper limb muscle loading, reported discomfort, and clinical findings associated with keyboard use. Surface electromyography (SEMG) was recorded bilaterally from the digit flexors (FDS), digit extensors (EDC), and m. trapezius of 52 employees of a large insurance company during their normal work activities involving keyboarding. Normalized SEMG amplitude served as a measure of loading on the relevant muscle groups. Physical examinations were conducted on these employees within 14 days of the EMG recording session, as was the administration of a discomfort questionnaire. The EMG measures of upper limb muscle loading did not predict MSD cases as well as the presence of current symptoms for forearm extensor cases (OR = 9.66), the duration of symptoms for neck/shoulder cases (OR = 2.5), or the intensity of symptoms for forearm flexor cases (OR = 3.72). However, the prediction of forearm extensor case status was improved by including the median EDC normalized EMG (OR = 1.39). The prediction of forearm flexor and neck/shoulder cases was not appreciably improved by including the FDS and trapezius EMG loading variables.

Aesthetic surgery: Coming of age

lation has resulted in a growing demand for such interventions to ameliorate the visible signs of ageing. Particular concerns are imperfections in the appearance of the skin, including unevenness in colour and texture, raised or depressed scars, wrinkles, sagging accumulations of subcutaneous fat, and hair loss. Fine wrinkling, photodamage caused by lifelong sun exposure, and scars caused by acne, chickenpox, surgery, or trauma can now be treated by laser resurfacing. High-energy shortpulsed or scanned carbondioxide lasers and pulsed erbium yttrium-aluminiumgarnet (YAG) lasers precisely remove skin tissue of uniform depth with little bleeding, while limiting the heat-related damage to surrounding tissues and so minimising the risk of scars and pigmentary changes. With proper selection of patients and wound care, the results of laser resurfacing are dramatic. Wrinkles round the eyes and mouth, typically unresponsive to face-lifting, can be successfully treated. Vascular lesions, such as superficial blood vessels, %elangiectasias, port-wine stains, haemangiomas, and leg veins, as well as scars, striae, and diffuse skin redness, can be treated quickly and effectively with several lasers, including the potassium-titanylphosphate laser and the newestgeneration pulsed-dye lasers, which can eliminate vascular patches with little or no bruising. Pigmented lesions, including tattoos and dark brown birthmarks, can be lightened with lasers that selectively destroy the pigment while sparing the adjacent tissue by emitting very short intense bursts of laser energy called Q-switched pulses. Qswitched lasers of specific wavelengths (Q-switched ruby, alexandrite, or neodymium YAG lasers) are best suited for removing tattoos of particular colours. Unwanted hair can also be treated quickly with lasers adapted for this purpose. Best results are seen in dark-haired, light-skinned patients, in whom a few treatments can result in a sharp permanent reduction in hair growth. Injectable or implantable filler substances are available for correction of soft-tissue losses from ageing, scarring, or skin disease. These materials can help reduce grooves between the cheeks and the nose as well as wrinkles, improve the contour of thinning lips, and fill deep acne scars. Bovine dermal collagen implants were approved in the USA by the Food and Drug Administration (FDA) in the early 1980s. Since then, autologous collagen products that may offer longer duration of correction and lower risk of allergic reactions have been developed, as have various Lower face before (top) and I month after C02 laser resurfacing other injectable substances, none of which are yet approved for use in the USA. Alternatively, fat can be taken from a non-facial site and implanted into facial sites in the same individual, thus eliminating the risk of immune reaction. Synthetic implantable agents--eg, expanded polytetrafluoroethylene--are available in various shapes and sizes and offer a permanent filling effect while being immunologically inert. Frown lines of the forehead and around the eyes respond well to treatment with botulinum A exotoxin. This substance, which is not yet approved for this indication by the FDA, is injected into the relevant muscle groups to provide relaxation of dynamic skin creases for 3-6 months. Age-related fat redistribution can occur in the cheeks and below the chin and jaw. Cervicofacial liposuction effectively removes fat from these regions and improves the contour of the neck and face. Liposuction also removes larger volumes of fat from other body areas that are resistant to diet and exercise, such as the upper arms, abdomen, hips, and thighs. Liposuction is safest and most effective with the tumescent anaesthetic technique--ie, injection of several litres of dilute lidocaine, epinephrine, and sodium bicarbonate into the subcutaneous fat before liposuction. The effects of fluid compression and epinephrine on the subcutaneous compartment allow use of high concentrations of lidocaine and decrease the need for sedation. Liposuction can now be done with little blood loss and with mild postoperative pain, swelling, and bruising. Improved techniques for hair transplantation have enabled a more natural appearance. Dermatological surgeons have learned to transplant hair singly or in groups of two or three into the balding scalp in the same configurations as on normal scalps. The technology is available to transplant even large bald patches within only one or two sessions. Given the demand for aesthetic procedures and the improvements that are increasing their efficacy, cosmetic dermatological surgery can be expected to remain a growing area within dermatology.

Influence of material handling devices on the physical load during the end assembly of cars

The effect of using a mechanical device on physical load was analysed during the end assembly of cars. Five tasks, further sub-divided into lifting and positioning, were performed by someone experienced in working with and without the mechanical tool. A practical methodology was used: the subjective walk and talk through method, the NIOSH equation (1991), a three-dimensional goniometer (Back Tracker) and surface electromyography (EMG) of the relevant muscle groups. According to the NIOSH equation, 8 out of 10 of the tasks should only be performed by trained workers and preferably with tools. The Back Tracker revealed that the mechanical tools reduced posture angles significantly ( p⩽0.05) for installing the windows, but not for left lateroflexion during pre-assembly of windows. It was clear from the EMG analysis that using tools did not always decrease muscular activity significantly. In general, the appropriateness of each tool needs to be evaluated separately taking the subjective criteria into account. Relevance to industry In this study, the relevance of using a mechanical device to reduce the physical load during car assembly, is evaluated. As the tools are expensive, it is important to the industry whether they are being used and how efficient they are.

Favorable movements of the hand-arm system in the horizontal plane assessed by electromyographic investigations and subjective rating

A study was carried out in order to analyze the influence of different movement directions on muscular strain of the hand–arm system when handling light weights. 11 female subjects had to perform a one-handed lifting task in the horizontal plane, moving repetitively objects of approximately 0 kg and of 1 kg on a table. Thirteen different directions in the frontal area had been provided. Electromyographic activity (EA) was continuously recorded from 8 muscles of the left hand–arm–shoulder system and the upper trunk. All data were standardized by the activity arising under maximum voluntary contractions (MVC). The EA-values were separated into static and dynamic components. Before the test, the subjects had to assess their preference of each direction. After each working direction the actually felt strain was rated on a scale. Both static and dynamic components of the muscular activity show a strong dependence on the moving direction. The directions around 30° (measured from the body plane) cause less than half of the muscular load in comparison with directions between 90° and 160°, which are often found in real work situations. When moving the weight of 1 kg EA-values up to 30% of the maximum EA were found. According to these findings the strain in the relevant muscle groups dependent on the working direction is not neglectable. When moving the nearly weightless object the recorded strain was also essential. The pure arm movement seems to be already responsible for a relatively high strain during this kind of work. The subjective ratings before the tests differed considerably from the physiological findings. The ratings after each test, however, corresponded with the measured strain in some important muscles which represent bottlenecks in repetitive manual movements. Relevance to industry The repetitive handling of light weights is often found in industrial workplaces, as for example in supermarket checkouts and in assembly-lines. The layout of these workplaces normally refers to static anthropometric data and not to the dynamics of the movements. Especially the direction of the movements is an important parameter for the muscular strain. Almost half of the static strain and a considerable part of the dynamic strain of some relevant muscles can be reduced if the workplaces are reconstructed according to the findings of this study.

Biology and medicine of sailing. An update.

The sport scientist's understanding of the biomechanics and physiology of sailing, together with its application to nutrition, training and injury prevention in the elite competitor, has continued to develop over the past decade. Very large mechanical forces are imposed in the vertical axis of the body, which give rise to frequent complaints to low back and knee pain and, occasionally, even to muscle rupture. Training programmes should emphasise the development of isometric endurance in the relevant muscle groups, such preparation continuing throughout the winter months. The oxygen cost of sailing is relatively light, and development of aerobic fitness should be advocated for reasons of general health rather than competitive success. Because of the intense muscle contractions that are developed during competition, heart rates and blood pressures are high in relation to oxygen consumption. However, during normal sailing, tacking and fluctuations of wind speed limit the development of muscle fatigue. In contrast to the operation of small craft, the crew of large ocean-going vessels may have a very high daily energy expenditure, probably related to difficulty in relaxing at any point of day or night. Windsurfers face similar physiological demands to the dinghy sailor and they also have frequent complaints of back pain. Knowledge of the relevant health issues remains limited, even among elite competitors, and there remains substantial scope for increased education of team members.

Analysis of the Tony!™ Variable Geometry VDT Keyboard

This study utilizes a variable geometry keyboard to analyze the optimal configuration for a split QWERTY-type keyboard. The measured criteria were muscle activity as measured by EMG and reported operator discomfort. A variable geometry keyboard, simultaneously adjustable in opening angle (yaw) and lateral angle (roll) was obtained. The upward slope (tilt) was preset at 10%. The study manipulated the keyboard geometry to assess the difference in musculoskeletal activity between using (1) a conventional, flat, linear keyboard; (2) a neutral, undeviated wrist position; and (3) two forearm positions that essentially eliminate pronation. Eight experienced subjects with no prior history of wrist injury or other pathology were tested. EMG activity of four relevant muscle groups was measured on each subject for each of the four keyboard positions. The study suggested an 18° opening angle and a 30°–60° lateral angle as optimal when compared with a flat, standard keyboard (they minimize objective EMG activity and subjective discomfort).