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At least 127 records · Page 7Linked to original sources

Assessment of vitamin B2 status in performance athletes of various types of sports.

To determine the vitamin B2 supply, 62 athletes in various types of sports and 16 non-athletes were examined, using a weighed food record (7-day), alpha-EGR determination, microbiological blood, and HPLC urinary measurements. If the guidelines of 1.5 or 1.7 mg/day vitamin B2 or 0.6 mg/4,184 kJ (GRDA) are defined for adequate status, all sports groups (M +/- SEM) are above this level. The vitamin B2 blood concentrations show a range (mean) from 303-372 nmol/liter, which indicates that more than 90% of the athletes are above the reference value of 327 nmol/liter (mean). There is a correlation of r = 0.49 between the vitamin B2 intake (mean over 7 days) and the vitamin B2 blood level. Determination of vitamin B2 blood concentration is characterized by good precision (C.V. +/- 3.2%) and recovery (95.7%). The enzyme activation measurement (alpha-EGR) shows that all of the athletes are below the alpha-EGR reference value of < 1.50 (good supply). No significant correlations could be determined between alpha-EGR and vitamin B2 intake, blood concentrations, and urinary excretion. The measurement also shows high precision (C.V. 1.7%). The Vitamin B2 excretion in urine (mumol/g Cr.) was higher than the reference values for non-athletes in more than 90% of the athletes. There is a correlation of r = 0.89 between the vitamin B2 intake on the last day (Day 7) of the food record and the riboflavin excretion, and between vitamin B2 in blood and urinary excretion of r = 0.52. The C.V. of vitamin B2 urinary measurement using HPLC is 2.5%, with recovery of 98.2%. Combined measurement of vitamin B2 intake, blood concentration, and urine excretion appears to be a suitable procedure for determining the vitamin B2 status. Most of the performance athletes were sufficiently supplied with vitamin B2, compared to the reference values for non-athletes.

Adolescent↗

Respiratory mechanics in Standardbred horses with sub-clinical inflammatory airway disease and poor athletic performance.

The aim of this study was to investigate and quantify respiratory mechanical dysfunctions in Standardbred horses with both poor performance and bronchoalveolar lavage fluid cytology characteristic of inflammatory airway disease (IAD). A control group of healthy Standardbred horses was compared. Respiratory mechanics and breathing pattern were examined at rest and during hyperventilation induced using a rebreathing method. At rest, respiratory mechanics and breathing pattern were superimposable in both groups. In IAD horses, rebreathing increased ventilation, with larger tidal volumes and lower respiratory frequencies. During hyperventilation, IAD animals showed frequency-dependent dynamic lung compliance, and had greater viscous lung resistance and rate of dynamic work of breathing. As IAD alters pulmonary mechanics, the ventilatory load increases and horses requiring significantly higher energy for breathing may suffer restrictions in their athletic performance. This rebreathing method permits early evaluation of respiratory mechanical dysfunction in poorly performing horses with sub-clinical IAD.

Animals↗

The role of vitamin C in athletic performance.

There is widespread belief among athletes that special nutritional practices--in particular high-protein diets--will enhance their achievements in competition. Supplementation with vitamins, especially vitamin C, is equally popular. But because genetic predisposition, hard physical training and psychological factors play a most important role in determining performance, and because any potential difference in achievement will be small, it is almost impossible to obtain scientific evidence of a beneficial effect of a particular nutrient. There have been many investigations during the past four decades of the potential effect of high-dose vitamin C supplementation on physical performance. The variables used have included maximum oxygen uptake, blood lactic acid levels, and heart rate after exercise, and in some cases performance was assessed in competitive events. The results have been equivocal: Most studies could not demonstrate an effect. On the other hand, a suboptimal vitamin C status results in an impaired working capacity which can be normalized by restoring vitamin C body pools. Athletes, who follow irrational, unhealthy eating patterns often not including vitamin-C-containing fruit and vegetables, are in need of nutrition education.

Animals↗

The effect of 7 to 8 months of vitamin/mineral supplementation on athletic performance.

The effect of vitamin and mineral supplementation was studied over 7 to 8 months of training and competition in 82 athletes from four sports: basketball, gymnastics, rowing, and swimming. Matched subgroups were formed and a double-blind design used, with subgroups being given either the supplementation or a placebo. All athletes were monitored to ensure that the recommended daily intakes (RDI) of vitamins and minerals were provided by diet alone. Sport-specific and some common tests of strength as well as aerobic and anaerobic fitness were performed. Coaches' assessment of improvement was also obtained. The only significant effect of supplementation was observed in the female basketball players, in which the supplementation was associated with increased body weight, skinfold sum, and jumping ability. A significant increase in skinfold sum was also demonstrated over the whole group as a result of supplementation. In general, however, this study provided little evidence of any effect of supplementation to athletic performance for athletes consuming the dietary RDIs.

Adolescent↗

Predicting athletic performance with self-confidence and somatic and cognitive anxiety as a function of motor and physiological requirements in six sports.

The purpose of the present study is to examine the ability of certain psychological attributes to predict performance in six National Collegiate Athletic Association Division I collegiate sports. Eighty-four athletes from the varsity sports teams of cross country running, alpine and nordic skiing, tennis, basketball, and track and field at the University of Colorado completed a questionnaire adapted from Martens (1977; Martens et al., 1983) that measured their trait levels of self-confidence (Bandura, 1977), somatic anxiety, and cognitive anxiety (Martens, 1977; Martens et al., 1983). In addition, at three to six competitions during the season, the members of the cross country running and tennis teams filled out a state measure (Martens et al., 1983) of the three attributes from one to two hours prior to the competition. Following each competition, subjective and objective ratings of performance were obtained, and, for all sports, coaches' ratings of performance and an overall seasonal team ranking were determined as seasonal performance measures. The sports were dichotomized along motor and physiological dimensions. Results indicate that all three psychological attributes were significant predictors of performance in both fine motor, anaerobic sports and gross motor, aerobic sports. Further, clear differences in these relationships emerged as a function of the dichotomization. In addition, unexpected sex differences emerged. The findings are discussed relative to prior research and their implications for future research.

Anxiety↗

Delayed menarche in swimmers in relation to age at onset of training and athletic performance.

Competitive swimmers have been considered to be different from other female athletes in that their mean age at menarche is similar to that of nonathletes. However, it was hypothesized that if the delayed menarche observed in athletes of other sports is caused by prepubertal training, then swimmers should also exhibit delayed menarche as the majority of swimmers begin training prior to puberty. Furthermore, if early prepubertal training is the important factor in delaying menarche, then it was hypothesized that a relationship between performance and age at menarche in swimming is unlikely to exist. Thus, 345 competitive female swimmers and 549 control subjects completed questionnaires concerning general health, athletic training history, and age at menarche. Results indicated that, as a population, the mean age at menarche of the swimmers (13.4 yr) was significantly later than the controls (13.0 yr). When swimmers and controls were compared on an age-group basis, it was found that the difference in age at menarche was due to the data obtained from the older and more highly competitive swimmers. Assigning swimmers to different competitive levels or by performance in specific swimming events (50- or 100-yd freestyle; 45.7- or 91.4-m, respectively) indicated a significantly later age at menarche for the more competitive swimmers. Thus, there is evidence that the age at menarche and subsequent athletic performance in swimming are related; the later menarche observed in swimmers appears to be associated with factors that select for superior performance.

Adolescent↗

RSR13, a potential athletic performance enhancement agent: detection in urine by gas chromatography/mass spectrometry.

RSR13 (2-[4-[[(3,5-dimethylanilino)carbonyl]methyl]phenoxyl]-2-methylpropionic acid) is a synthetic allosteric modifier of hemoglobin that is currently in a phase III clinical trial as a radio-enhancing agent. RSR13 has been shown to increase maximum oxygen uptake (VO(2max)) in a canine skeletal model, which makes it a potential performance-enhancing agent for endurance athletes, since VO(2max) is an index of aerobic capacity. In this study we present a method for the detection of RSR13-bis-TMS in human urine by gas chromatography/electron impact ionization mass spectrometry (GC/EI-MS) suitable for doping control laboratories. The presence of RSR13 is detected by monitoring the ions m/z 485 ([M](+.)) and 470 ([M - CH3](+)). The limit of detection (LOD) is less than 2 ng/mL in urine. Urine samples collected from clinical trial subjects immediately prior to receiving an infusion of RSR13 showed no evidence of RSR13, whereas post-infusion urine samples contained up to 1181 microg/mL. A urine sample collected 36 h after administration of a small dose (10 mg/kg) and diluted 100-fold showed a signal 80 times higher than the LOD. Urine samples obtained from 100 randomly selected athletes in our routine testing program did not show any traces of RSR13. Sport authorities may wish to add RSR13 to the list of prohibited substances.

Aniline Compounds↗

[Modification of bone quality by extreme physical stress. Bone density measurements in high-performance athletes using dual-energy x-ray absorptiometry].

The treatment of osteoporosis is still controversial. Rehabilitation programs which stress strengthening exercises as well as impact loading activities increase the bone mass. On the other side activity level early in life has not been proven to correlate with increased bone mineral content later in life. Little is known on the influence of high performance sports on the bone density especially in athletes with high demands on weight bearing of the spine. In (n = 40) internationally top ranked high performance athletes of different disciplines (n = 28 weight-lifters, n = 6 sports-boxers and n = 6 bicycle-racers) bone density measurements of the lumbar spine and the left hip were performed. The measurements were carried out by dual-photonabsorptiometry (DEXA; QDR 2000, Siemens) and evaluated by an interactive software-programme (Hologic Inc.). The results were compared to the measurements of 21 age-matched male control individuals. In the high performance weight lifters there was an increase of bone density compared to the control individuals of 23% in the Ward's triangle (p < 0.01). The sports-boxers had an increase up to 17% (lumbar spine), 9% (hip) and 7% (Wards' triangle). In the third athletes group (Tour de France-bikers) BMD was decreased 10% in the lumbar spine, 14% in the hip and 17% in the Wards' triangle. Our results show that training programs stressing axial loads of the skeletal system may lead to an increase of BMD in the spine and the hip of young individuals. Other authors findings, that the BMD of endurance athletes may decrease, is confirmed. Nevertheless the bikers BMD-loss of 10 to 17% was surprisingly high.

Absorptiometry, Photon↗