shoulders, 10 , 12 which led to imbalances between the UT and the other ST muscles. 10 Furthermore, an abnormal muscle activation pattern of the MT and LT has been found in overhand athletes with impingement symptoms. 9 Nevertheless, it is still unclear whether such shoulder girdle muscle impairments are
Samuele Contemori and Andrea Biscarini
João Breno Ribeiro-Alvares, Maurício Pinto Dornelles, Carolina Gassen Fritsch, Felipe Xavier de Lima-e-Silva, Thales Menezes Medeiros, Lucas Severo-Silveira, Vanessa Bernardes Marques and Bruno Manfredini Baroni
. Deficits in hamstring concentric or eccentric strength were marked when a leg presented a deficit >15% compared with the contralateral leg (bilateral asymmetry). 10 , 11 The normative value of 0.6 for the H/Q conventional ratio has been widely used for identifying strength imbalance in football players
Hae-rim Han, Chung-hwi Yi, Sung-hyun You, Heon-seock Cynn, One-bin Lim and Jae-ik Son
imbalance results from an impaired relationship between muscles prone to tightness and muscles prone to weakness. Specifically, the TFL is included in the tonic muscle system (tendency to have muscles prone to tightness; movement group), and the GMED is included in the phasic muscle system (tendency to have
Marcus B. Stone, Jeffrey E. Edwards, Catherine L. Stemmans, Christopher D. Ingersoll, Riann M. Palmieri and B. Andrew Krause
Despite recent evidence to suggest that exercise-associated muscle cramps (EAMC) might be primarily of neuromuscular origin, the authors surmise that most information available to certified athletic trainers (ATCs) emphasizes the role of dehydration and electrolyte imbalance in EAMC.
To investigate ATCs' perceptions of EAMC.
7-question, Web-based, descriptive, cross-sectional survey.
Main Outcome Measures:
Responses to 7 questions regarding the cause, treatment, and prevention of EAMC.
Responders indicated humidity, temperature, training, dehydration, and electrolyte imbalance as causative factors of EAMC. Fluid replacement and stretching the involved muscle were identified as very successful in treating and preventing EAMC. Proper nutrition and electrolyte replacement were also perceived as extremely successful prevention strategies.
ATCs' perceptions of the cause, treatment, and prevention of EAMC are primarily centered on dehydration and electrolyte imbalance. Other prominent ideas concerning EAMC should be implemented in athletic training education.
Nicola Marotta, Andrea Demeco, Gerardo de Scorpio, Angelo Indino, Teresa Iona and Antonio Ammendolia
. Conclusions The combination of surface electromyography with inertial sensor demonstrated differences in male and female muscle activation time during an athletic maneuver that mimics an often-cited mechanism of ACL injury. In this context, the neuromotor imbalance of VM’s late activation in females puts the
James O. Hill and Reneé Commerford
In this paper, we review the impact of physical activity on energy and maeronutrient balances. Stability of body weight and body composition depends on reaching a steady-state where the amount and composition of energy ingested are equal to the amount and composition of energy expended. We describe how a person's level of physical activity can have a significant impact on determining the level of body weight and body fatness at which that steady-state is reached. First, physical activity can directly affect both total energy intake and total energy expenditure. Physical activity can also affect fat balance, and it is becoming clear that imbalances in total energy are largely imbalances in fat. High levels of physical activity should help individuals reach fat and energy balances at lower levels of body fatness than would have been achieved at lower levels of physical activity.
Gary E. Morin, David Tiberio and Gary Austin
A characteristic of scapulothoracic dysfunction is the tendency for the upper regions of the trapezius to hypertrophy in relation to its middle and lower portions. This creates a muscular imbalance that can alter scapular position and subsequently the length–tension relationship of the shoulder muscles. Tape was applied over the right upper trapezius to inhibit electrical activity in the muscles of 10 uninjured subjects. EMG activity was recorded in two locations of the upper trapezius and one location in the middle to lower trapezius region while each subject maintained an isometric contraction designed to activate both muscles. With the tape applied, there was a statistically significant reduction in EMG activity of the upper trapezius with a corresponding increase in the middle/lower trapezius. The ability of the tape to alter trapezius activity in this fashion may help correct muscular imbalances in the trapezius muscle.
Lawrence E. Armstrong
Recreational enthusiasts and athletes often are advised to abstain from consuming caffeinated beverages (CB). The dual purposes of this review are to (a) critique controlled investigations regarding the effects of caffeine on dehydration and exercise performance, and (b) ascertain whether abstaining from CB is scientifically and physiologically justifiable. The literature indicates that caffeine consumption stimulates a mild diuresis similar to water, but there is no evidence of a fluid-electrolyte imbalance that is detrimental to exercise performance or health. Investigations comparing caffeine (100-680 mg) to water or placebo seldom found a statistical difference in urine volume. In the 10 studies reviewed, consumption of a CB resulted in 0-84% retention of the initial volume ingested, whereas consumption of water resulted in 0-81% retention. Further, tolerance to caffeine reduces the likelihood that a detrimental fluid-electrolyte imbalance will occur. The scientific literature suggests that athletes and recreational enthusiasts will not incur detrimental fluid-electrolyte imbalances if they consume CB in moderation and eat a typical U.S. diet. Sedentary members of the general public should be at less risk than athletes because their fluid losses via sweating are smaller.
Gregory G. Billy and Sayers J. Miller
An avid weightlifter presented with complaints of right arm and hand numbness. His workup was consistent with neurologic thoracic outlet syndrome with severe conduction block at the level of the supraclavicular fossa. He chose conservative treatment, which focused on correction of thoracic and cervical segmental dysfunction, upper crossed syndrome muscle imbalances, and upper trunk and anterior forward head postural concerns. Upon completion of the therapy program and continuation of a home exercise program, his conduction block and symptoms resolved. Conservative treatment may be an effective alternative to surgery for neurologic thoracic outlet syndrome.
Donal Murray, Kevin C. Miller and Jeffrey E. Edwards
Although exercise-associated muscle cramps (EAMC) are common in ultradistance runners and athletes in general, their etiology remains unclear. EAMC are painful, sudden, involuntary contractions of skeletal muscle occurring during or after exercise and are recognized by visible bulging or knotting of the whole, or part of, a muscle. Many clinicians believe EAMC occur after an imbalance in electrolyte concentrations, specifically serum sodium concentration ([Na+]s) and serum potassium concentration ([K+]s). Studies that have established a link between EAMC occurrence and serum electrolyte concentrations after an athletic event are unhelpful.
Focused Clinical Question:
Are [Na+]s and [K+]s different in athletes who experience EAMC than noncrampers?