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At least 343 records · Page 19Linked to original sources

PubMed1993

The influence of fructose feeding on physical performance.

Athletic competition requires great energy expenditure and the ability to maintain performance depends on an adequate supply of metabolic fuels, which has led to the use of dietary supplements. Much of the data concerning fructose supplementation is contradictory in nature, but it shows that fructose feeding before or during exercise can enhance performance under certain conditions. Preexercise nutrition seems to be the most important condition to be met. It has been theorized that prefeeding elevates liver glycogen and spares muscle glycogen, which prolongs activity. There is also good evidence to indicate that the addition of fructose to the diet during ultraendurance events can improve performance by 126%. The gastrointestinal discomfort created by large amounts of fructose can hinder performance and has limited research with this supplement. Therefore, even though positive effects have been demonstrated, more research is needed to determine the role that fructose can play in enhancing athletic performance.

Dietary Carbohydrates↗

PubMed1990

Upper-extremity rehabilitation: conditioning and orthotics for the athlete and performing artist.

Rehabilitation of athletes or musicians with hand injuries begins immediately after injury. Accurate diagnosis of the injury and tissues involved is followed by specific acute and rehabilitative therapies to correct the injury and determine any biomechanical changes that may have occurred. Medication and physical methods aid in decreasing inflammation and pain. Mobility is progressively restored, with the aid of appropriate heating modalities, as soon as signs and symptoms allow. Proprioception and neuromuscular coordination are then retrained. This is followed by balanced muscle strength training. Finally, sport-specific endurance and biomechanical skills are developed. Emotional aspects of the injury may be dealt with by investigating the physical and emotional stresses of the performance, and discussing them with the patient. Some patients may also be helped by psychologic counseling. Orthotics may be used to decrease swelling, decrease pain, and inhibit unwanted motion. Some variations allow for progressive range of motion and strength building. Attention to these details maximizes the chances of successful return to performance in the athlete or performing artist with a hand injury.

Athletic Injuries↗

PubMed2000

Special feature for the Olympics: effects of exercise on the immune system: overtraining effects on immunity and performance in athletes.

Overtraining is a process of excessive exercise training in high-performance athletes that may lead to overtraining syndrome. Overtraining syndrome is a neuroendocrine disorder characterized by poor performance in competition, inability to maintain training loads, persistent fatigue, reduced catecholamine excretion, frequent illness, disturbed sleep and alterations in mood state. Although high-performance athletes are generally not clinically immune deficient, there is evidence that several immune parameters are suppressed during prolonged periods of intense exercise training. These include decreases in neutrophil function, serum and salivary immunoglobulin concentrations and natural killer cell number and possibly cytotoxic activity in peripheral blood. Moreover, the incidence of symptoms of upper respiratory tract infection increases during periods of endurance training. However, all of these changes appear to result from prolonged periods of intense exercise training, rather than from the effects of overtraining syndrome itself. At present, there is no single objective marker to identify overtraining syndrome. It is best identified by a combination of markers, such as decreases in urinary norepinephrine output, maximal heart rate and blood lactate levels, impaired sport performance and work output at 110% of individual anaerobic threshold, and daily self-analysis by the athlete (e.g. high fatigue and stress ratings). The mechanisms underlying overtraining syndrome have not been clearly identified, but are likely to involve autonomic dysfunction and possibly increased cytokine production resulting from the physical stress of intense daily training with inadequate recovery.

Blood Cells↗

PubMed2001

Use of oral creatine as an ergogenic aid for increased sports performance: perceptions of adolescent athletes.

BACKGROUND: Competitive athletes, including adolescents, seek ways to gain advantage over competitors. One ergogenic aid is creatine, a naturally occurring nitrogen compound found primarily in skeletal muscle. Increasing creatine levels may prolong skeletal muscle activity, enhancing work output. METHODS: A questionnaire assessing awareness and use of creatine supplementation was completed by 674 athletes from 11 high schools. Data were statistically analyzed to determine variation among groups. RESULTS: Of those surveyed, 75% had knowledge of creatine supplements, and 16% used creatine to enhance athletic performance. Percentage of use increased with age and grade level. Awareness and use were greater among boys than girls. Adverse effects were reported by 26%. Most athletes consumed creatine using a method inconsistent with scientific recommendations. CONCLUSIONS: Use of creatine by adolescent athletes is significant and inconsistent with optimal dosing. Physicians, athletic trainers, and coaches should disseminate proper information and advise these adolescent athletes.

Administration, Oral↗

PubMed1990

Endurance running performance in athletes with asthma.

Laboratory assessment was made during maximal and submaximal exercise on 16 endurance trained male runners with asthma (aged 35 +/- 9 years) (mean +/- S.D.). Eleven of these asthmatic athletes had recent performance times over a half-marathon, which were examined in light of the results from the laboratory tests. The maximum oxygen uptake (VO2max) of the group was 61.8 +/- 6.3 ml kg-1 min-1 and the maximum ventilation (VEmax) was 138.7 +/- 24.7 l min-1. These maximum cardio-respiratory responses to exercise were positively correlated to the degree of airflow obstruction, defined as the forced expiratory volume in 1 s (expressed as a percentage of predicted normal). The half-marathon performance times of 11 of the athletes ranged from those of recreational to elite runners (82.4 +/- 8.8 min, range 69-94). Race pace was correlated with VO2max (r = 0.863, P less than 0.01) but the highest correlation was with the running velocity at a blood lactate concentration of 2 mmol l-1 (r = 0.971, P less than 0.01). The asthmatic athletes utilized 82 +/- 4% VO2max during the half-marathon, which was correlated with the %VO2max at 2 mmol l-1 blood lactate (r = 0.817, P less than 0.01). The results of this study suggest that athletes with mild to moderate asthma can possess high VO2max values and can develop a high degree of endurance fitness, as defined by their ability to sustain a high percentage of VO2max over an endurance race. In athletes with more severe airflow obstruction, the maximum ventilation rate may be reduced and so VO2max may be impaired. The athletes in the present study have adapted to this limitation by being able to sustain a higher %VO2max before the accumulation of blood lactate, which is an advantage during an endurance race. Therefore, with appropriate training and medication, asthmatics can successfully participate in endurance running at a competitive level.

Adult↗

PubMed1994

Effects of bodyweight reduction on sports performance.

Athletes reduce bodyweight for several reasons: to compete in a lower weight class; to improve aesthetic appearance; or to increase physical performance. Rapid bodyweight reduction (dehydration in 12 to 96 hours), typically with fluid restriction and increased exercise, is used by athletes competing in weight-class events. Gradual bodyweight reduction (over > 1 week) is usually achieved by cutting energy intake to 75 to 130 kJ/kg/day. An intake of 100 kJ/kg/day results in a weekly bodyweight loss of roughly 1kg. Aerobic endurance capacity decreases after rapid bodyweight reduction, but might increase after gradual bodyweight reduction. Maximal oxygen uptake (VO2max) measured as L/min is unchanged or decreased after bodyweight loss, but VO2max measured as ml/kg/min may increase after gradual bodyweight reduction. Anaerobic performance and muscle strength are typically decreased after rapid bodyweight reduction with or without 1 to 3 hours rehydration. When tested after 5 to 24 hours of rehydration, performance is maintained at euhydrated levels. A high carbohydrate diet during bodyweight loss may help in maintaining performance. Anaerobic performance is not affected and strength can increase after gradual bodyweight reduction. Reductions in plasma volume, muscle glycogen content and the buffer capacity of the blood explain decreased performance after rapid bodyweight reduction. During gradual bodyweight loss, slow glycogen resynthesis after training, loss of muscle protein and stress fractures (caused by endocrinological disorders) may affect performance. Athletes' bodyweight goals should be individualised rather than by comparing with other athletes. If the time between weigh-in and competition is < 5 hours, rapid bodyweight reduction should not exceed 4% of bodyweight. If the time interval is longer, a bodyweight reduction < or = 8% might be acceptable. A moderate-energy (100 to 120 kJ/kg/day) and high-carbohydrate (60 to 70% of total energy intake) diet is recommended. Gradual bodyweight reduction may be 0.5 to 1.5 kg/week. Energy intake should be 80 to 120 kJ/kg/day, with a high carbohydrate (60 to 70%) and a low fat (15 to 25%) content.

Anaerobic Threshold↗

PubMed1994

Disordered eating in active and athletic women.

In an attempt to improve athletic performance, some female athletes develop patterns of disordered eating. The spectrum of disordered eating ranges from mild to severe, with the severe form resulting in anorexia nervosa or bulimia nervosa. Disordered eating can result in decreased athletic performance, increased morbidity, and occasional mortality.

Adult↗

PubMed1977

Anaerobic performance capacity in athletes.

Anaerobic performance characteristics of the whole body and at muscle tissue level were studied in 89 athletes and 31 reference subjects. The main parameters were vertical velocity during running up the stairs, maximal isometric force of leg extensor muscles, blood lactate concentration after maximal treadmill running test, percentage of fast twitch muscle fibers (% FT fibers), lactate dehydrogenase (LDH) and creatine phosphokinase (CPK) activity in vastus lateralis muscle. These parameters tended to divide the athletes and their sport events into neuromuscular, anaerobic and aerobic types. The specific needs of the different sport events might have masked the expected characteristics of energy and power utilization. However, a high percentage of FT fibers might be a prerequisite for a successful athlete in certain neuromuscular-anaerobic type events ("power events"). The main parameters describing the anaerobic performance capacity of the whole body (vertical velocity, leg force, blood lactate) were found to be related to muscle fiber composition (% FT fibers). The running velocity rather than muscle strength seemed to be more influenced by activity of enzymes LDH and CPK.

Adult↗

PubMed1996

The effects of semirigid Air-Stirrup bracing vs. adhesive ankle taping on motor performance.

The impact on athletic performance is a critical consideration when choosing ankle support devices for competitive athletes. The purpose of this study was to determine if Air-Stirrup ankle bracing and adhesive ankle taping differed in their effects on motor performance. An additional purpose was to determine if there was a subjective preference toward the use of one support method over the other. Twenty-six male athletes performed an agility run, a 40-yard sprint, and a vertical jump while wearing: 1) adhesive tape, 2) Air-Stirrup brace, and 3) no support (control). Observed data suggest that both taping and bracing have no substantial effect on agility, sprinting speed, or vertical jumping ability. The difference in perceived comfort ratings reported by subjects with respect to support system shows that subjects were more comfortable using the brace over a standard ankle taping procedure. These results suggest that both the Air-Stirrup brace and conventional tape do not impede athletic performance. This study may assist athletes and clinicians in making a more informed selection of a prophylactic ankle support device when considering the effect on performance and comfort.

Adhesives↗

PubMed1985

Normalizing the performances of athletes in Olympic weightlifting.

A method of comparing the performances of athletes of disparate bodyweights in Olympic weightlifting is developed that is able to accommodate the fact that, of the ten bodyweight classes contested, the lighter nine have upper limits assigned to them while the heaviest has only a lower limit. The results are presented so as to answer the question "What would a given athlete weighing x kilograms total if he were a +110 kg. athlete of the same level of ability?"

Body Weight↗

PubMed1985

The use and abuse of anabolic steroids in Olympic-caliber athletes.

Self-medication with anabolic steroids by athletes, particularly in the sports of weight lifting and track and field, has become increasingly popular. In the 1983 Pan American Games, 15 athletes were disqualified for taking anabolic steroids. Athletes take steroids believing the steroids will allow increased periods of intensive training and will increase muscle strength with proper weight training. The athletes assume this increased strength and training will translate into better athletic performance. Most athletes taking anabolic steroids are taking very large doses with no thought as to the potential adverse side effects. They ignore the possibility of long-term problems relating to hypertension, liver dysfunction, and atherosclerosis for what they see as the immediate performance benefits. In an attempt to keep sports competition "clean" and to help protect athletes from harmful drugs, the International Olympic Committee (IOC) and the United States Olympic Committee have rules stating that the use of anabolic steroids is illegal. Drug testing is performed in Olympic and in many international competitions. Those people found using anabolic steroids are disqualified. This use of anabolic steroids indicates that for some athletes the need to win or to maximize performance supersedes any worries about future health.

Anabolic Agents↗

PubMed2006

Sex differences in baseline neuropsychological function and concussion symptoms of collegiate athletes.

OBJECTIVE: To investigate sex differences in baseline neuropsychological function and concussion symptoms between male and female collegiate athletes. METHODS: A post-test only design was used to examine baseline neuropsychological test scores and concussion symptoms. A total of 1209 NCAA Division I collegiate athletes from five northeastern universities in the USA completed a baseline ImPACT test. ImPACT, a computerised neuropsychological test battery, was administered during an athlete's pre-season. RESULTS: Female athletes performed significantly better than male athletes on baseline verbal memory scores (p = 0.001), while male athletes performed significantly better than female athletes on baseline visual memory scores (p = 0.001). Female athletes endorsed a significant number of mild baseline symptoms as compared to male athletes. CONCLUSIONS: Male and female athletes exhibit differences on baseline neuropsychological test performance and concussion symptoms.

Athletic Injuries↗

PubMed2000

A perspective on fat intake in athletes.

Performance in endurance events is dependent upon the maximal aerobic power, the percentage of that power that can be sustained and the availability of substrates (carbohydrates [CHO] and fats). The purpose of this paper is to present a perspective of recent studies that demonstrate the role of fat intake and oxidation on endurance performance. Studies have shown that fatigue is associated with reduced muscle glycogen and that increasing muscle glycogen or blood glucose prolongs performance while increasing fat and decreasing CHO decreases performance. This has led to an emphasis on CHO intake in athletes in endurance sports, which quite often leads to low caloric intake. It is well known that trained subjects have higher levels of fat oxidative capacity, which spares glycogen during endurance sports. Data from recent studies in trained athletes, who were fed iso-caloric high-fat diets (42% to 55%) that maintained adequate CHO levels, have shown an increase in endurance in both men and women when compared to diets composed of low fat intake (10% to 15%). The magnitude of the effect on endurance was significant at high percentages of maximal aerobic power and increased as the percentage of maximal aerobic power decreased. Based on this review, a baseline diet comprising 20% protein, 30% CHO and 30% fat, with the remaining 20% of the calories distributed between CHO and fat based on the intensity and duration of the sport, is recommended for discussion and future research.

Adult↗

PubMed2002

Intermittent hypoxic training: fact and fancy.

Intermittent hypoxic training (IHT) refers to the discontinuous use of normobaric or hypobaric hypoxia, in an attempt to reproduce some of the key features of altitude acclimatization, with the ultimate goal to improve sea-level athletic performance. In general, IHT can be divided into two different strategies: (1) providing hypoxia at rest with the primary goal being to stimulate altitude acclimatization or (2) providing hypoxia during exercise, with the primary goal being to enhance the training stimulus. Each approach has many different possible application strategies, with the essential variable among them being the "dose" of hypoxia necessary to achieve the desired effect. One approach, called living high-training low, has been shown to improve sea-level endurance performance. This strategy combines altitude acclimatization (2500 m) with low altitude training to ensure high-quality training. The opposite strategy, living low-training high, has also been proposed by some investigators. The primacy of the altitude acclimatization effect in IHT is demonstrated by the following facts: (1) living high-training low clearly improves performance in athletes of all abilities, (2) the mechanism of this improvement is primarily an increase in erythropoietin, leading to increased red cell mass, V(O2max), and running performance, and (3) rather than intensifying the training stimulus, training at altitude or under hypoxia leads to the opposite effect - reduced speeds, reduced power output, reduced oxygen flux - and therefore is not likely to provide any advantage for a well-trained athlete.

Acclimatization↗

PubMed2002

Effect of mandibular orthopedic repositioning appliance on kinematic pattern in golf swing.

Experience has shown that repositioning the mandible may have an influence on the athletic performance. Many athletes with or without occlusal problems are now using mandibular orthopedic repositioning appliance (MORA) supposedly to optimize their performance. In golf, the players do not have any direct opponent and they have different clubs to reach various distances. Therefore, an automatic swing permits the uncertainty of the movement to be restricted. The aim of this study was to analyze if the use of the MORA could have an effect on the stability of the kinematic pattern in golf swing, connected to the capacity of the golfers to reproduce their swing from kinematic perspective. The measures of kinematic data have been established with the optoelectronic system VICON (Oxford's Metrix, Oxford, UK) with five cameras operating at 50 frames per second. Measurements of the speed of the ball at impact were obtained with a radar (Bridgestone HD.01, Science eye, USA). Six professional (current handicap ranging from 0 to 4) right-handed golfers participated in the study. Six MORA were made and adjusted to fit each player. Each golfer performed five swings without mouthpiece and five with the MORA. The results of this study show that there was no difference related to the MORA on kinematic pattern of the golf swing. Moreover, there were significant differences concerning the ball speed at the impact, among the two test conditions, with or without the appliance (p < 0.03). The percentage of variability indicates that the speed with MORA was more regular than the speed without the appliance.

Adolescent↗

PubMed2000

Colic surgery in 206 juvenile thoroughbreds: survival and racing results.

The purpose of our study was to determine the types of lesions that cause colic in juvenile Thoroughbreds, factors associated with these lesions and the subsequent survival and athletic performance of the juveniles. The age of juvenile Thoroughbreds requiring surgical exploration for abdominal pain has an influence on the type of lesion causing colic. The short-term survival rate (discharge from the hospital) after colic surgery for foals was 85% and was strongly influenced by the lesion causing colic. Thirteen percent of juveniles recovered from the first surgery experienced another severe colic episode requiring additional surgery or euthanasia. Eight percent of foals recovered from the first celiotomy developed adhesions. Adhesion formation was related to the initial lesion causing colic and the foals' age at the first surgery. Foals being suckled (15 days to 6 months) were at greatest risk for adhesions and more frequently required multiple surgeries. Juvenile Thoroughbreds that had a celiotomy were significantly less able to race (63%) than their unaffected siblings (82%), and age at the initial surgery was associated with the percentage of horses that raced. However, affected foals able to race won as much money, raced as often, and made as many starts as their siblings. Colic and surgical treatment have a negative impact on athletic performance, but the majority of foals discharged from the hospital after colic surgery will perform athletically as adults.

Animals↗

PubMed1995

Macronutrients and performance.

Athletes should eat a well-balanced diet made up of a wide variety of foods in sufficient quantity to cover their daily energy expenditures. Carbohydrate-containing foods should provide approximately 60-70% of their daily energy intake, protein approximately 12-15%, with the remainder being provided by fat. The higher carbohydrate intakes, however, are only recommended during preparation for, and immediate recovery from, heavy training and competition. Adopting nutritional strategies to increase muscle and liver glycogen stores before, during and after exercise can improve performance. The protein requirements of most athletes are fulfilled when their daily intake is between 1.2 and 1.7 g per kg body mass. This amount of protein is provided by a diet which covers the athlete's daily energy expenditure. Although fat metabolism contributes to energy production during exercise, and the amount increases with endurance training, there is no evidence to suggest that athletes should increase their fat intake as a means of improving their performance.

Dietary Carbohydrates↗

PubMed2006

The use of nutritional supplements among master athletes.

We assessed the use of nutritional supplements among master athletes focusing on their source of information and source of supply of nutritional supplements. 1560 standardized, anonymous questionnaires were distributed among participants of the World Masters Athletics Championships Indoors 2004. These questions were related to biometric parameters, social indicators, training parameters, illicit drugs, and nutritional supplements. Chi2-tests were computed to reveal meaningful associations between basic information (age, gender, family status, children, education, country of origin, disciplines, training years, smoking, and the use of alcohol, illicit drugs, and doping) and the intake of nutritional supplements. Descriptive information on the history of their use of nutritional supplements was also provided. 60.5 % of all participants reported the actual use of nutritional supplements. We found no significant differences between nutritional supplement users and non-users with regard to basic information. The substances predominantly used were vitamins (35.4 %) and minerals (29.9 %). In contrast to elite athletes who use nutritional supplements to increase their athletic performance, master athletes use these substances predominantly for health reasons and, thus, have a closer contact to the health care system. Physicians are their preferred source of information about nutritional supplements. More than half of the interviewed athletes obtain their nutritional supplements from pharmacies or physicians. The results of this study indicate that nutritional supplement users in master athletics show no specific user profile. Since it is not rare for nutritional supplements to contain trace contaminations of anabolic androgenic steroids or pro-hormones, physicians should also inform master competitive athletes of the dangers of testing positive for doping substances due to their intake of nutritional supplements and advise them accordingly.

Adult↗