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Query: UMLS:C0038454 (stroke)
 147,016 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

One of several factors suspected in the development of lateral epicondylitis, often referred to as tennis elbow, is the impact-induced vibration of the racket-and-arm system at ball contact. Using two miniature accelerometers at the wrist and the elbow of 24 tennis players, the effects of 23 different tennis racket constructions were evaluated in a simulated backhand stroke situation. The influences of body weight, skill level, and tennis racket construction onto the magnitude of vibrations at wrist and elbow were investigated. Amplitudes, integrals, and fourier components were used to characterize arm vibration. More than fourfold reductions in acceleration amplitude and integral were found between wrist and elbow. Off-center as compared with center ball impacts resulted in approximately three times increased acceleration values. Between subjects, body weight as well as skill level were found to influence arm vibration. Compared with proficient players, a group of less skilled subjects demonstrated increased vibration loads on the arm. Between different racket constructions, almost threefold differences in acceleration values could be observed. Increased racket head size as well as a higher resonance frequency of the racket were found to reduce arm vibration. The vibration at the arm after ball impact showed a strong inverse relationship (r = -0.88) with the resonance frequency of tennis rackets.
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PMID:Transfer of tennis racket vibrations onto the human forearm. 143 61

Tennis elbow afflicts 40% to 50% of the average, recreational tennis players; most of these players more than 30 years of age. Tennis elbow is thought to be the result of microtrauma, the overuse and inflammation at the origin of the ECRB as a result of repeated large impact forces created when the ball hits the racket in the backhand stroke. Several authors have found that EMG activity in the ECRB, the muscle and tendon complex afflicted in tennis elbow, is high during the acceleration and early follow-through phases of the groundstrokes and during the cocking phase of the serve. Unfortunately, none of the authors gave evidence to support the claim that muscle activity in the ECRB at ball contact is high. In the one-handed backhand, the torques at impact (17-24 nm) will be absorbed by the tendons of the elbow. Giangarra and his colleagues observed that the two-handed backhand "allows the forces at ball impact to be transmitted through the elbow rather than absorbed by the tissues at the elbow." Other authors have reported that players using a two-handed backhand will rarely develop lateral epicondylitis, because the helping arm appears to absorb more energy and changes the mechanics of the swing. As seen by Morris and colleagues, Giangarra and associates, and Leach and colleagues, players who utilize the two-handed backhand have a very low incidence of tennis elbow. These three studies conclude that the two-handed backhand stroke is probably the most effective backhand stroke to prevent lateral tennis elbow. Studies show that wrist extensors are highly involved in all strokes (serve, forehand, and both one- and two-handed backhand strokes). This relatively high involvement (40%-70% MVC) throughout play may result in overload of this muscular group. Thus, tennis elbow may be caused simply by continued use of this muscular system in all strokes, and not just because of the high forces absorbed at impact. Another theory concerning impact states that if the extensor group is already at near maximum contraction, vibrations and twisting movements are transferred directly through the muscle (muscle stiffness at this point would be great) to the tendinous insertion, causing repeated microtrauma. If the muscle is the stiffest element in the system, the force will be transferred to the tendon. It is evident that a need exists for specific study of muscular response during impact. More microanalysis of the impact phase needs to be conducted specifically for the one-handed backhand groundstroke.
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PMID:The biomechanics of tennis elbow. An integrated approach. 771 57

Investigators have suggested that the greater prevalence of lateral humeral epicondylitis (tennis elbow, TE) in novice tennis players compared to expert players may reflect the novice players' use of faulty mechanics for the backhand stroke. We investigated the wrist kinematics (flexion/extension), grip pressures, and wrist muscle electromyographic activity in novice (N = 8) and expert (N = 8) tennis players performing the backhand stroke. Experts performed the backhand stroke with the wrist extended (re: neutral alignment of the forearm and hand dorsum). Collision of the ball and racket occurred with the wrist extended on average of 0.41 rad (about 23 degrees from neutral alignment) in the expert players; moreover, their wrists were moving further into extension at impact. In contrast, novice subjects struck the ball with the wrist flexed 0.22 rad (about 13 degrees) while moving their wrists further into flexion. Wrist extensor EMGs showed similar levels of activity during the 500 ms interval before ball-racket impact, whereas expert subjects displayed greater EMG levels after contact, consistent with the accompanying wrist extension. The wrist kinematic and EMG data together show that the novice subjects eccentrically contracted their wrist extensor muscles throughout the stroke. We argue that conditions exist for novice subjects that assist stretch of wrist extensor muscles upon collision of the ball and racket. The resulting eccentric contraction of wrist extensor muscles may contribute to lateral TE in novice players, given previous research indicating that eccentric muscle contraction facilitates muscle fiber injury.
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PMID:Wrist kinematics differ in expert and novice tennis players performing the backhand stroke: implications for tennis elbow. 802 87

Lateral epicondylitis occurs frequently in tennis players and appears to be caused by tears in the extensor aponeurosis. The purpose of this study was to compare the electromyographic activities of 5 muscles in players with lateral epicondylitis with those of injury-free players during the single-handed backhand tennis stroke. Finewire electrodes were placed into the extensor digitorum communis, extensor carpi radialis longus and brevis, pronator teres, and flexor carpi radialis muscles in competitive tennis players; 8 players had lateral epicondylitis and 14 had normal upper extremities. The backhand stroke then was recorded on high-speed film and synchronized with the electromyographic signal. The injured players had significantly greater activity for the wrist extensors and pronator teres muscles during ball impact and early follow-through. This activity increase may have been caused by the abnormal mechanics evident on film, including a "leading elbow," wrist extension and an open racquet face near the time of ball impact, and ball contact in the lower half of the strings. These mechanics not only result in a lower level of play but also leave the wrist extensors and the pronator teres muscles vulnerable to injury. This is the first study that documents increased activity in muscles that have been previously injured.
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PMID:Electromyographic and cinematographic analysis of elbow function in tennis players with lateral epicondylitis. 803 77

It is generally believed that tennis players using a double-handed backhand rarely develop lateral epicondylitis since the helping arm appears to absorb more energy and changes the mechanics of the swing. The purpose of this paper was to compare muscle activity about the elbow in single- and double-handed backhand strokes in competitive tennis players. Muscle activity in 3 elbow extensors, a wrist flexor, and a forearm pronator of the dominant arm was compared during the single-handed (N = 14) and double-handed (N = 13) backhand ground strokes using indwelling electromyography and high-speed cinematography. Significantly higher activity was seen in the double-handed technique in the flexor carpi radialis muscle in the preparation phase and in the pronator teres muscle in the acceleration phase. Higher flexor carpi radialis muscle activity in preparation of the double-handed stroke appeared to be a function of the double-handed grip used on the racquet, and the increased pronator teres muscle activity in acceleration indicated maintenance of greater pronation provided by the grip of the non-dominant hand. The decreased occurrence of lateral epicondylitis in players using a double-handed backhand may not be caused by decreased extensor activity, but rather by factors associated with flawed stroke mechanics more often seen in the single-handed technique.
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PMID:Electromyographic and cinematographic analysis of elbow function in tennis players using single- and double-handed backhand strokes. 834 54

Participation in the sport of rowing has been steadily increasing in recent decades, yet few studies address the specific injuries incurred. This article reviews the most common injuries described in the literature, including musculoskeletal problems in the lower back, ribs, shoulder, wrist and knee. A review of basic rowing physiology and equipment is included, along with a description of the mechanics of the rowing stroke. This information is necessary in order to make an accurate diagnosis and treatment protocol for these injuries, which are mainly chronic in nature. The most frequently injured region is the low back, mainly due to excessive hyperflexion and twisting, and can include specific injuries such as spondylolysis, sacroiliac joint dysfunction and disc herniation. Rib stress fractures account for the most time lost from on-water training and competition. Although theories abound for the mechanism of injury, the exact aetiology of rib stress fractures remains unknown. Other injuries discussed within, which are specific to ribs, include costochondritis, costovertebral joint subluxation and intercostal muscle strains. Shoulder pain is quite common in rowers and can be the result of overuse, poor technique, or tension in the upper body. Injuries concerning the forearm and wrist are also common, and can include exertional compartment syndrome, lateral epicondylitis, deQuervain's and intersection syndrome, and tenosynovitis of the wrist extensors. In the lower body, the major injuries reported include generalised patellofemoral pain due to abnormal patellar tracking, and iliotibial band friction syndrome. Lastly, dermatological issues, such as blisters and abrasions, and miscellaneous issues, such as environmental concerns and the female athlete triad, are also included in this article.Pathophysiology, mechanism of injury, assessment and management strategies are outlined in the text for each injury, with special attention given to ways to correct biomechanical or equipment problems specific to rowing. By gaining an understanding of basic rowing biomechanics and training habits, the physician and/or healthcare provider will be better equipped to treat and prevent injuries in the rowing population.
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PMID:Rowing injuries. 1597 36

We review the evidence of botulinum toxins in the treatment of pain. Main indications of botulinum toxin treatment, dystonia and spasticity, involve pain. Increasing evidence suggests direct analgesic effects of botulinum. Botulinum inhibits release of pain mediators (substance P, CGRP, excitatory amino acids, ATP, noradrenaline). Clinical trials have consistently shown analgesic effect of botulinum toxin in post-stroke shoulder pain, bladder dysfunction, chronic migraine, neuropathic pain, bruxism and lateral epicondylitis. Other pain conditions have been studied with yet uncertain results. It seems that the number of patients who would benefit from botulinum toxin treatment will increase considerably in the future.
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PMID:[Botulinum toxins for pain]. 2223 20

Botulinum toxin (BTX) is used for multiple clinical indications due to its ability to induce temporary chemodenervation and muscle paralysis. This property has supported its application in treating a variety of musculoskeletal conditions, especially those involving muscular hyperactivity and contractures such as cerebral palsy and dystonia. However, off-label use of BTX injection in other musculoskeletal disorders is gaining increased acceptance, such as in neurogenic thoracic outlet syndrome, epicondylitis, and shoulder pain after stroke. This review discusses the mechanism of action, best practices, and current indications of BTX injections in the musculoskeletal system. We also discuss the state of the science regarding BTX injections for musculoskeletal disorders and the available evidence supporting its use.
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PMID:Botulinum Toxin Injections in Musculoskeletal Disorders. 2800 66

Bee venom acupuncture is a form of acupuncture in which bee venom is applied to the tips of acupuncture needles, stingers are extracted from bees, or bees are held with an instrument exposing the stinger, and applied to acupoints on the skin. Bee venom is a complex substance consisting of multiple anti-inflammatory compounds such as melittin, adolapin, apamin. Other substances such as phospholipase A2 can be anti-inflammatory in low concentrations and pro-inflammatory in others. However, bee venom also contains proinflammatory substances, melittin, mast cell degranulation peptide 401, and histamine. Nevertheless, in small studies, bee venom acupuncture has been used in man to successfully treat a number of musculoskeletal diseases such as lumbar disc disease, osteoarthritis of the knee, rheumatoid arthritis, adhesive capsulitis, and lateral epicondylitis. Bee venom acupuncture can also alleviate neurological conditions, including peripheral neuropathies, stroke and Parkinson's Disease. The treatment has even been piloted in one series to alleviate depression. An important concern is the safety of bee venom. Bee venom can cause anaphylaxis, and several deaths have been reported in patients who successfully received the therapy prior to the adverse event. While the incidence of adverse events is unknown, the number of published reports of toxicity is small. Refining bee venom to remove harmful substances may potentially limit its toxicity. New uses for bee venom acupuncture may also be considered.
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PMID:To bee or not to bee: The potential efficacy and safety of bee venom acupuncture in humans. 3026 93