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PubMedDate not supplied

Body composition of elite American athletes.

Five hundred twenty-eight male athletes participating in 26 Olympic events and 298 female athletes participating in 15 Olympic events underwent determination of body fat percentage (% fat) and lean body mass (LBM) via hydrostatic weighing and/or anthropometric methods. All groups of athletes were below the average values for % fat of college age men and women of 15% and 25%, respectively. In general, athletes involved in a sport where their body weight is supported, such as canoe and kayak (males, 13.0 +/- 2.5%; females, 22.2 +/- 4.6%) and swimming (males, 12.4 +/- 3.7%; females 19.5 +/- 2.8%), tended to have higher % fat values. Athletes involved in sports where a weight class has to be made to compete, such as boxing (males, 6.9 +/- 1.6%) and wrestling (male, Junior World Freestyle 7.9 +/- 2.7%), events such as the 100, 200, and 400 meters in athletes (male 100 and 200 meters, 6.5 +/- 1.2%; female 100, 200 and 400 meters, 13.7 +/- 3.6%) that are very anaerobic in nature and extremely aerobic events such as the marathon (males, 6.4 +/- 1.3%) demonstrated lower % fat values. Athletes involved in sports where body size is a definite advantage, such as basketball (males, 84.1 +/- 6.2 kg; females, 55.3 +/- 4.9 kg) and volleyball (males, 75.0 +/- 6.6 kg; females, 58.4 +/- 4.5 kg) tended to have a larger LBM.

Adipose Tissue↗
PubMedDate not supplied

The muscle fiber composition of skeletal muscle as a predictor of athletic success. An overview.

Human skeletal muscle is composed of varying percentages of fiber types. This percent composition varies widely between muscles and among individuals. The fiber composition of some skeletal muscle could be construed as being advantageous to successful performance in selected athletic event. However, this relationship is not sufficiently close to warrant the conclusion that the fiber composition of the muscle per se is the determinant of the superior performance of elite athletes. Reasonably good evidence exists to support the position that the fiber composition of a muscle is the result of a genetic endowment. Although muscle fibers are mutable, present evidence is equivocal as to whether habitual participation in given type of physical activity is responsible for high percentages of a given fiber type being present in the muscles of some athletes. Although considerable knowledge has come from the study of muscle samples obtained from sedentary individuals, athletes of a wide range of performance capacity, and individuals before and after training, a considerable gap remains for a full understanding of how the characteristics of muscle are related to performance capacity. The observation that considerable variation exists in the percent distribution of the fibers within a muscle and that athletes with a wide range of fiber populations in their muscles can be successful in the same athletic event cautions against the routine application of the biopsy technique to estimate the fiber distribution of muscles and also to use such data as a routine screening procedure for predicting athletic success. The point, as was made in an earlier paper, that the biopsy technique for studying muscle is a research tool, will probably continue to be true for the near future.

Adenosine Triphosphate↗
PubMedDate not supplied

Shoulder pain in wheelchair athletes. The role of muscle imbalance.

Shoulder rotator cuff impingement syndrome is a common and disabling problem for the wheelchair athlete. In this study we investigated the role of shoulder strength imbalance as a factor for the development of this syndrome. Nineteen paraplegic male athletes underwent clinical and isokinetic examination of both shoulders with peak torque values measured in abduction, adduction, and internal and external rotation. Twenty athletic, able-bodied men without shoulder problems were tested as controls. Ten (26%) of the paraplegic athletes had rotator cuff impingement syndrome. The results of the isokinetic testing demonstrated that 1) the paraplegics' shoulders were stronger than the controls in all directions (P < 0.05); 2) the strength ratio of abduction: adduction was higher for paraplegic athletes (P < 0.05); 3) paraplegics' shoulders with rotator cuff impingement syndrome were weaker in adduction and external and internal rotation than the paraplegic athletes without impingement syndrome (P < 0.05); and 4) paraplegics' shoulders with rotator cuff impingement syndrome had higher abduction:adduction and abduction:internal rotation strength ratios than the shoulders of paraplegics without impingement syndrome (P < 0.05). We concluded that shoulder muscle imbalance, with comparative weakness of the humeral head depressors (rotators and adductors), may be a factor in the development and perpetuation of rotator cuff impingement syndrome in wheelchair athletes.

Adult↗
PubMed2004

The female athlete triad.

The Female Athlete Triad is a syndrome of the interrelated components of disordered eating, amenorrhea, and osteoporosis. Sometimes inadvertently, but more often by willful dietary restriction, many female athletes do not ingest sufficient calories to adequately fuel their physical or sport activities, which can disrupt menstrual functioning, thereby increasing their risk of bone loss. Although its prevalence is unknown, the Female Athlete Triad is believed to affect many athletes at all ages and all sport competition levels. Even though the Triad affects athletes in all sports, girls and women in sports that emphasize a thin or small body size or shape appear to be most at risk. This article focuses on the risks of the Female Athlete Triad for middle- and high-school-age female athletes as well as the unique issues related to the identification, management, and treatment of the various components of the Triad in this special adolescent subpopulation.

Adolescent↗
PubMed2005

Sports nutrition for young athletes.

Nutritional needs for peak athletic performance include sufficient calorie intake, adequate hydration, and attention to timing of meals. Student athletes and their advisors often are misinformed or have misconceptions about sports nutrition. This paper identifies nutritional needs of young athletes, reviews common misconceptions, and examines the nutrition knowledge of athletes and their sources of nutrition information. Topics covered include energy, carbohydrate, protein, fat and micronutrient needs, hydration requirements, timing of meals, and issues related to age, gender, and specific sports. Other issues addressed include "making weight" and ergogenic aids. Proper nutrition for young athletes is critical not only to their athletic success, but more importantly to their growth, development, and overall health. Nutritional recommendations should be based on the most current scientific data; we provide information about appropriate resources for the school nurse when advising student athletes and their coaches and parents.

Adolescent↗
PubMed2004

Amenorrhea in female athletes is associated with endothelial dysfunction and unfavorable lipid profile.

The aim of this study was to evaluate endothelial function measured as flow-mediated dilatation (FMD) of the brachial artery and blood markers of cardiovascular disease in young female endurance athletes with menstrual disturbance. Age- and body mass index-matched groups of young endurance athletes with amenorrhea (n = 14), oligomenorrhea (n = 9), and regular cycles (n = 12) and sedentary controls (n = 12) were compared with respect to endothelial function, lipid profile, markers of inflammation, and endocrine status. We found a significantly decreased FMD in the amenorrheic athletes, compared with all other groups. Amenorrheic athletes also had the most unfavorable lipid profile with significantly higher total cholesterol and low-density lipoprotein, compared with the other athlete groups. The oligomenorrheic athletes had the lowest levels of total cholesterol, low-density lipoprotein, and apolipoprotein B of all groups and significantly lower in comparison with the amenorrheic group. However, with respect to FMD, the oligomenorrheic group represented an intermediate between amenorrheic and regularly cycling subjects. There was a gradual impairment of FMD and the lipid profile to the degree of menstrual disturbance supporting an association with estrogen status. We conclude that amenorrhea in young endurance athletes is associated with endothelial dysfunction and unfavorable lipid profile. Additional studies are needed to elucidate the clinical implications of these results with regard to long-term risk for cardiovascular disease.

Adolescent↗
PubMed2005

Oral contraceptives improve endothelial function in amenorrheic athletes.

Athletic amenorrhea has been associated with endothelial dysfunction and unfavorable lipid profile. Estrogen substitution may reverse these metabolic consequences. The aim of this study was to evaluate the effects of oral contraceptives (OCs) on endothelial function measured as flow-mediated dilatation (FMD) of the brachial artery, the lipid profile, and blood markers of endothelial activation (inflammation) in amenorrheic athletes. Age- and body mass index-matched groups of young endurance athletes with amenorrhea (n = 11), regularly cycling athletes (n = 13), and sedentary controls (n = 12) were examined before and after 9 months of treatment with a low dose, monophasic, combined OC (30 mug ethinyl estradiol and 150 mug levonorgestrel). The amenorrheic athletes displayed the lowest FMD at baseline and the largest increase after OC treatment. FMD also increased in the control group, but not in the regularly menstruating athletes, who had the highest values of FMD before treatment. All three groups, particularly the controls, showed moderate unfavorable changes in the lipid profile in accordance with previous known effects of a second generation OC. Furthermore, there was an overall increase in some inflammatory markers (high sensitive C-reactive protein and TNF-alpha) and a decrease in one of the markers (vascular cell adhesion molecule-1). We conclude that amenorrheic athletes benefit from treatment with OC with respect to endothelial function. OC treatment is also associated with some modest alterations in the lipid profile and in markers of inflammation.

Adolescent↗
PubMed1992

Hypothalamic-pituitary-thyroidal function in eumenorrheic and amenorrheic athletes.

The impact of chronic high volume athletic training on thyroid hormone economy has not been defined. We investigated the status of the hypothalamic-pituitary-thyroid axis (H-P-T) in women athletes with regular menstrual cycles (CA) and with amenorrhea (AA). Their data were compared with each other and with those derived from cyclic sedentary women (CS) matched for a variety of confounding factors including the intensity of exercise, caloric intake, and body weight. Alterations of the H-P-T axis were observed in women athletes compared to CS. While serum levels of T4, T3, free T4, free T3 and rT3 were substantially reduced (P less than 0.01) in AA, only serum T4 levels were significantly decreased in CA. Further, remarkable differences were found between CA and AA in that serum levels of free T4 (P less than 0.01), free T3 (P less than 0.01), and rT3 (P less than 0.05) were significantly lower in AA than in CA. Thyroid binding globulin and sex-hormone binding globulin concentrations were within their normal ranges for all groups of subjects. Both 24-h mean TSH levels and the circadian rhythm of TSH secretion were also comparable. However, the TSH response to TRH stimulation was blunted (P less than 0.01) in AA when compared to CA, but not to CS. Whereas the underlying mechanism(s) to account for the "global" reduction of circulating thyroid hormone in the face of normal TSH levels in AA is presently unknown, these observations provide information of clinical significance: 1) chronic high volume athletic training in women athletes with menstrual cyclicity is accompanied by an isolated T4 reduction; 2) an impaired H-P-T axis occurs selectively in athletic women in whom chronic high volume athletic training is associated with compromised hypothalamic-pituitary-ovarian function and amenorrhea.

Adult↗
PubMed1995

Elevated basal adrenocorticotropin and evidence for increased central opioid tone in highly trained male athletes.

Basal cortisol and ACTH levels have previously been shown to be elevated in highly trained athletes, whereas the ACTH response to ovine CRH has been reported to be diminished compared to that in nonathletic controls. Naloxone, a nonselective opioid receptor antagonist, is known to stimulate ACTH and cortisol secretion. The mechanism of this response is thought to be via increased hypothalamic CRH secretion. The aim of this study was to examine basal and naloxone-stimulated levels of hypothalamic-pituitary-adrenal axis hormones in male athletes. Ten highly trained male athletes and 10 nonathletic controls took part in the study. Peripheral venous blood was sampled for cortisol, ACTH, CRH, and arginine vasopressin (AVP) for 2 h before the administration of 20 mg naloxone, i.v., and 15, 30, 45, 60, 90, and 120 min after naloxone treatment. Body mass index was significantly lower in the athletes (P < 0.001). Basal (prenaloxone) ACTH levels were higher in the athletes (P < 0.05), whereas levels of cortisol, CRH, and AVP were similar in both groups. After naloxone treatment, there was a significantly greater rise in ACTH in the athletes (P < 0.02). There was also a trend for the cortisol response to be greater, which was not statistically significant (P < 0.07). Although in both groups, peripheral CRH rose after naloxone treatment (P < 0.005), a rise of similar magnitude occurred over the 2-h period before naloxone (P < 0.0001). Plasma AVP did not change significantly after naloxone treatment. Neither the plasma cortisol level at baseline nor the body mass index correlated significantly with the ACTH or cortisol response to naloxone. The presence of an enhanced ACTH response to naloxone is evidence that central opioid tone may be increased in highly trained athletes. However, there is no associated suppression of the hypothalamic-pituitary-adrenal axis, and basal ACTH levels are raised, without any detectable change in peripheral plasma CRH or AVP. An additional factor (other than CRH) that stimulates ACTH secretion may be released after naloxone administration.

Adrenocorticotropic Hormone↗
PubMed2006

Epstein-Barr virus serostatus: no difference despite aberrant patterns in athletes and control group.

PURPOSE: To investigate the Epstein-Barr virus (EBV) serostatus in an athletic endurance population, especially the prevalence of complex aberrant EBV antibody patterns. In addition, the purpose was to determine whether serology in athletes is more complex than in the general population. METHODS: The study protocol included serological testing of 202 advanced endurance athletes (biathlon, cycling, nordic skiing (state to international level); mean age 19 +/- 4) and 200 control subjects (mean age 23 +/- 2). Twenty-microliter serum samples were examined using a strip immunoassay with antigens produced by recombinant techniques for detection of EBV IgG antibodies: anti-EBNA-1 (anti-EBV nuclear antigen-1), anti-p18, anti-p23, anti-p138, anti-p54, and anti-BZLF-1. Avidity determination was used to differentiate further between acute, recent, and past infections. RESULTS: Athletes showed 35 negative (17%), 6 unresolvable (3%), 1 acute (0.5%), 11 recent (5%), 122 past (61%), and 27 aberrant past (mainly anti-EBNA-1 negative) (13.5%) cases. The control group showed 31 negative (16%), 4 unresolvable (2%), 1 acute (0.5%), 1 recent (0.5%), 135 past (68%), and 28 (14.0%) aberrant past cases. Although endurance athletes included more recent infections (several months since acute infection), there was no significant difference (P = 0.144) in the total constellation of EBV serostatus between the groups. CONCLUSION: No evidence was found for the assumption that endurance athletes are more susceptible to EBV infections than the general population. In addition, no differences were found with respect to serological classical and aberrant complicated patterns between athletes and the control group. Those cases that may lead to false diagnoses of acute EBV infection in previously used test systems because of a negative anti-EBNA-1 are common in both groups but were unambiguously resolved by the Recomline EBV IgG test applied here.

Acute Disease↗
PubMed2006

Perceptions of empathic accuracy and assumed similarity in the coach-athlete relationship.

Drawing upon the methodology developed by Kenny and Acitelli (2001), this study examined empathic accuracy and assumed similarity in both parties' perceptions of coach-athlete relationships. One hundred and twenty-one coaches and athletes reported on their direct-perceptions and meta-perceptions of closeness, commitment and complementarity (3 Cs; Jowett & Cockerill, 2002), and of satisfaction with instruction, performance and external agents. There was evidence of both empathic accuracy and assumed similarity in coaches' and athletes' perceptions. Athletes were more accurate in identifying the specific content of their coaches' feelings in terms of closeness. Athletes and coaches from newly developed relationships displayed higher levels of empathic accuracy, whereas female athletes displayed higher levels of assumed similarity. Moreover, evidence suggested that athletes' and coaches' assumed similarity led to more accurate perceptions. Implications and future research directions are discussed.

Adult↗
PubMed2004

Comparing jumping ability among athletes of various sports: vertical drop jumping from 60 centimeters.

Drop jumping performance (DJP) is of high importance in order to achieve sporting performance in both team and individual sports. The purpose of the present study was to compare DJP among athletes from various sports. One hundred thirty-eight male athletes (age: 22.3 +/- 3.6 years, body height: 1.87 +/- 0.08 m, body mass: 81.8 +/- 10.8 kg) from 6 different sports performed drop jumps from 60 cm (DJ60) on a force plate. Results revealed that volleyball players jumped higher (p < 0.001) than other athletes. However, track and field athletes produced higher peak force and higher power output using a shorter upward phase (p < 0.001). Further examination using principal components analysis (PCA) revealed that team sport athletes and single scull rowers exhibited DJP utilizing force and time parameters differently than track and field athletes. Conclusively, DJP was different among athletes of various sports. Furthermore, PCA can be a useful method for evaluating the above mentioned differences and for monitoring drop jumping training programs.

Adult↗
PubMed2001

Creatine use among young athletes.

OBJECTIVE: Creatine is a nutritional supplement that is purported to be a safe ergogenic aid in adults. Although as many as 28% of collegiate athletes admit taking creatine, there is little information about creatine use or potential health risk in children and adolescents. Although the use of creatine is not recommended in people less than 18 years of age, numerous anecdotal reports indicate widespread use in young athletes. The purpose of this study was to determine the frequency, risk factors, and demographics of creatine use among middle and high school student athletes. METHODS: Before their annual sports preparticipation physical examinations, middle and high school athletes aged 10 to 18 in Westchester County, a suburb north of New York City, were surveyed in a confidential manner. Information was collected regarding school grade, gender, specific sport participation, and creatine use. RESULTS: Overall, 62 of 1103 participants (5.6%) admitted taking creatine. Creatine use was reported in every grade, from 6 to 12. Forty-four percent of grade 12 athletes surveyed reported using creatine. Creatine use was significantly more common (P <.001) among boys (53/604, 8.8%) than girls (9/492, 1.8%). Although creatine was taken by participants in every sport, use was significantly more common among football players, wrestlers, hockey players, gymnasts, and lacrosse players (P <.001 for all). The most common reasons cited for taking creatine were enhanced performance (74.2% of users) and improved appearance (61.3%), and the most common reason cited for not taking creatine was safety (45.7% of nonusers). CONCLUSIONS: Despite current recommendations against use in adolescents less than 18 years old, creatine is being used by middle and high school athletes at all grade levels. The prevalence in grades 11 and 12 approaches levels reported among collegiate athletes. Until the safety of creatine can be established in adolescents, the use of this product should be discouraged.

Adolescent↗
PubMed2006

Popular ergogenic drugs and supplements in young athletes.

Ergogenic drugs are substances that are used to enhance athletic performance. These drugs include illicit substances as well as compounds that are marketed as nutritional supplements. Many such drugs have been used widely by professional and elite athletes for several decades. However, in recent years, research indicates that younger athletes are increasingly experimenting with these drugs to improve both appearance and athletic abilities. Ergogenic drugs that are commonly used by youths today include anabolic-androgenic steroids, steroid precursors (androstenedione and dehydroepiandrosterone), growth hormone, creatine, and ephedra alkaloids. Reviewing the literature to date, it is clear that children are exposed to these substances at younger ages than in years past, with use starting as early as middle school. Anabolic steroids and creatine do offer potential gains in body mass and strength but risk adverse effects to multiple organ systems. Steroid precursors, growth hormone, and ephedra alkaloids have not been proven to enhance any athletic measures, whereas they do impart many risks to their users. To combat this drug abuse, there have been recent changes in the legal status of several substances, changes in the rules of youth athletics including drug testing of high school students, and educational initiatives designed for the young athlete. This article summarizes the current literature regarding these ergogenic substances and details their use, effects, risks, and legal standing.

Adolescent↗
PubMed2004

Decrease in neuromuscular control about the knee with maturation in female athletes.

BACKGROUND: Compared with male athletes, female athletes demonstrate increased dynamic valgus angulation of the knee during landing from a jump, although prior to maturation male and female athletes have similar forces and motions about the knee when they land from a jump. Our hypothesis was that musculoskeletal changes that accompany maturation result in poor neuromuscular control of the knee joint in female athletes. METHODS: One hundred and eighty-one middle-school and high-school soccer and basketball players-100 girls and eighty-one boys-participated in the study. Dynamic control of the knee joint was measured kinematically by assessing medial knee motion and the lower-extremity valgus angle and was measured kinetically by assessing knee joint torques; the values were then compared between female and male athletes according to maturational stage. Lower-extremity bone length was measured with three-dimensional kinematic analysis. RESULTS: Following the onset of maturation, the female athletes landed with greater total medial motion of the knees and a greater maximum lower-extremity valgus angle than did the male athletes. The girls also demonstrated decreased flexor torques compared with the boys as well as a significant difference between the maximum valgus angles of their dominant and nondominant lower extremities after maturation. CONCLUSIONS: After girls mature, they land from a jump differently than do boys, as measured kinematically and kinetically.

Adolescent↗
PubMed1990

Athletic performance following rapid traversal of multiple time zones. A review.

Athletes travel across multiple time zones in order to engage in national or international competition. It has often been assumed that rapid transmeridian translocation has a negative impact on athletic performance. However, the available studies are characterised by major methodological problems. Consequently, no compelling evidence exists demonstrating that air travel adversely influences athletic performance. Evidence suggests that distance and sprint running performance, as well as dynamic muscular strength and endurance of the elbow flexors, is impaired following west-east travel across 6 times zones in untrained individuals. However, there is no evidence that these findings for untrained subjects generalise to athletes. Both physiological and psychological mechanisms might account for potential effects of travel on athletic performance, but little is known about these potential mechanisms with regards to athletic performance. Systematic research is needed if the relationship between air travel and athletic performance is to be elucidated.

Aircraft↗
PubMed1991

Enhancement of athletic performance with drugs. An overview.

Drug use among athletes has become a recognised problem in sports. Athletes may use drugs for therapeutic indications, for recreational or social reasons, as ergogenic aids or to mask the presence of other drugs during drug testing. Stimulants were some of the first drugs used and studied as ergogenic aids. Amphetamines may increase time to exhaustion by masking the physiological response to fatigue. Caffeine may improve utilisation of fatty acids as a fuel source thereby sparing muscle glycogen. Cocaine and other sympathomimetic drugs have little or no effect on athletic performance. Anabolic steroids appear to have the potential to increase lean muscle mass and strength under certain conditions. Human growth hormone may also be used for an anabolic effect, but data on this effect are lacking. Erythropoietin may represent a pharmacological alternative to blood doping by increasing red blood cell mass. The use of narcotic analgesics is not necessarily ergogenic but can be harmful if used to allow participation of an athlete with a severe injury. According to the American College of Sports Medicine alcohol does not possess an ergogenic effect. However, it may be used to reduce anxiety or tremor prior to competition. Marijuana does not increase strength. Tobacco products may produce psychomotor effects or control appetite which may be beneficial to some athletes. Other drugs used by athletes include beta-blocking agents, diuretics, and a variety of nutritional supplements. In addition, diuretics and probenecid may be taken to mask drug contents in the urine. Whether the ergogenic effects are real or perceived, the potential for adverse effects exists for all of these drugs. Potential health complications represent a serious risk to an otherwise healthy population. Further research on the long term health risks in athletes taking ergogenic drugs is needed.

Adrenergic beta-Antagonists↗
PubMed1997

Cardiovascular evaluation of the athlete. Issues regarding performance, screening and sudden cardiac death.

Recent studies have reported ECG anomalies and a high prevalence of exercise-related arrhythmias among well trained, apparently healthy endurance athletes with superior levels of cardiorespiratory fitness. The occurrence of sudden and premature cardiac deaths in amateur and professional athletes, who appear to embody all of the virtues of health and fitness, ahs raised our consciousness regarding the underlying atherosclerotic or nonatherosclerotic causes, and the need for, and extent of, preparticipation screening in competitive athletes. It appears that strenuous physical activity may trigger acute cardiovascular events in some athletes. Coronary artery disease is the most frequent autopsy finding in those over the age of 35 years who die suddenly. In contrast, structural cardiovascular abnormalities, including hypertrophic cardiomyopathy and malformations of the coronary arteries, are the major cause of sudden death in younger athletes. This article reviews these issues, with specific reference to the assessment of cardiorespiratory fitness, legal and prohibited performance-altering medications, the pathophysiological basis of exertion-related untoward events, the athlete at risk, limitations of conventional screening programmes and contemporary recommendations to identify latent cardiovascular disease in athletic populations.

Anaerobic Threshold↗