Medicine and science in sports and exercise
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Med Sci Sports Exerc · Aug 1993
Practice Guideline GuidelineCurrent comment from the American College of Sports Medicine. August 1993--"The prevention of sport injuries of children and adolescents".
Many children and adolescents choose to participate in organized sports for fun and fitness, and to develop sports skills. However, new injury patterns are developing as the number of children and adolescents in organized sports increases--injury patterns that were not apparent when youth spent most of their sport and fitness time in free play. Up to one half of all injuries that are sustained by children and adolescents while playing organized sports are likely preventable. ⋯ It delineates injury prevention strategies that should be included in the pre-participation examination; stresses the importance of adherence to recommended training principles; and discusses appropriate modifications of game rules and sport and fitness activities as needed for individuals who would likely be at risk for injury should adult rules and training methods be followed. Children and adolescents should include fitness exercises in the training routine, rather than devoting all of each training session to the development of specific skills required for a certain sport. The fitness activities may be geared toward the strength, endurance, and flexibility requirements of the specific sport, but should not exclude other components of a well-rounded general fitness program.(ABSTRACT TRUNCATED AT 250 WORDS)
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Med Sci Sports Exerc · May 1993
Effects of iron supplementation and discontinuation on serum copper, zinc, calcium, and magnesium levels in women.
The purpose of this study was: 1) to establish the prevalence of depleted iron stores, iron deficiency, and low serum levels for copper, zinc, calcium, and magnesium in a healthy female population; and 2) to examine the effects of iron supplementation and discontinuation on the serum levels of the above minerals. One hundred eleven healthy women between the ages of 18 and 40 yr reported for fasted morning blood sampling for iron, copper, zinc, calcium, and magnesium status. Forty-five subjects were either iron-deficient as defined by a hemoglobin level below 120 g.l-1 (four subjects) or iron deplete as defined by a serum ferritin value below 20 micrograms.l-1 (43 subjects). ⋯ The main conclusions to be made from this study were that: 1) For this sample population of women, iron depletion was quite common (39%), although low hemoglobin values (< 120 g.l-1) were only seen in 3.6%. No subjects fell below the criteria for low serum copper levels (< 13.3 mumol.l-1) nor low serum magnesium levels (< 0.6 mmol.l-1). Seven subjects (6.5%) fell below the criteria for low serum zinc levels (< 11.5 mumol.l-1) while two subjects (1.8%) were below the criteria for low serum calcium levels (< 2.20 mmol.l-1). 2) Therapeutic oral iron supplementation was successful in raising mean serum ferritin values from 15.9 micrograms.l-1 to 36.5 micrograms.l-1 but was not associated with decrements in serum copper or calcium levels. 3) The treatment did not significantly effect serum zinc and magnesium levels during the supplementation period, but a downward trend continued through the discontinuation phase so that at 18 and 24 wk serum zinc and magnesium levels were significantly lower than baseline. 4) Oral contraceptive use was associated with elevated serum copper and ferritin values and lowered serum magnesium levels.
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Med Sci Sports Exerc · Mar 1993
Relationship of oxygen consumption and cardiac output to work of breathing.
This study examined the relationship between work of breathing and estimated blood flow to and oxygen consumption by the respiratory muscles. Five subjects performed inspiratory loaded breathing and voluntary hyperpnea while ventilatory work, cardiac output, and oxygen consumption were measured. Blood flow to and oxygen consumption by the respiratory muscles were estimated by subtracting the resting from the working values of cardiac output the oxygen consumption, respectively. ⋯ During hyperpnea both cardiac output and oxygen consumption were correlated with work of breathing. Our results indicate that blood flow and oxygen consumption are increased in a regular pattern with increases in work of breathing. These results may be significant in estimating the demand of the respiratory muscles in disease and exercise.
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Med Sci Sports Exerc · Jan 1993
Effects of electrolytes in carbohydrate beverages on gastric emptying and secretion.
Two experiments were done at rest to examine gastric residue and secretion volume and electrolyte composition after ingestion of beverages of varying composition. In the first experiment the effects of two different sport drinks, one isotonic (7% carbohydrate, primarily sucrose) (I) and one hypertonic (18% carbohydrate, primarily maltodextrin) (H), and a control beverage (0.08 g.l-1 aspartame in water) (C) on titratable acid, pH, osmolality, gastric emptying and secretion volume, and Na+, K+, and Cl- content were measured. In a second experiment five solutions were tested all containing 150 g.l-1 maltodextrin, with 28 meq.l-1 Na+ (low Na), 140 meq.l-1 Na+(high Na), 28 meq.l-1 K+(K), or 140 meq.l-1 Na+ and 28 meq.l-1 K+(high NaK). ⋯ Secretion was decreased in these two solutions versus all the others. Although nonsignificant, there was a trend for greater secretion in H versus the other carbohydrate containing solutions in experiment 2. This may be a result of the higher pH maintained after ingestion of this beverage.
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The greatest catastrophy in sports is an athlete's unexpected sudden death. Identifying those athletes at risk remains a great challenge to physicians performing preseason examinations. Hypertrophic cardiomyopathy is the most common cause of nontraumatic sudden death in athletes. ⋯ The case presented exemplifies the attention to detail required to differentiate the borderline diseased heart from the conditioned athletic heart. Once a diagnosis of hypertrophic cardiomyopathy is made, further participation in intense physical exercise is discouraged. This recommendation is necessary despite the unknown relative sudden death risk for the minimal criteria cases.