Exercise performance as a function of semi-solid and liquid carbohydrate feedings during prolonged exercise.

Aim of this study was to examine the effects of a semi-solid and a liquid carbohydrate feeding on exercise performance. Thirty-two male triathletes performed three exercise trials (3 hours maximal at 75% VO2max) with either a semi-solid feeding (S), an iso-caloric liquid feeding (F) or a liquid placebo (P). Exercise consisted of cycling (bout 1 and 3) and running (bout 2 and 4).

Lipids and apoproteins in relation to participation in organized sport activities and pubertal development in boys.

This study considers changes in the plasma lipid and apoprotein profiles of boys in relation to participation in organized sport activities and to testosterone (T) levels. Fifty boys, aged 9.9 ± 0.

Gastrointestinal problems as a function of carbohydrate supplements and mode of exercise.

The aim of the study was to examine prevalence and duration/seriousness of gastrointestinal (GI) problems as a function of carbohydrate-rich (CHO) supplements and mode of exercise. The relationship between GI problems and a variety of physiological and personal factors (age, exercise experience) was also examined. Thirty-two male tri-athletes performed three experimental trials at 1-wk intervals, each trial on a different supplement: a conventional, semisolid supplement (S; 1.

The onset of puberty and the availability of sex steroids in female gymnasts.

Plasma levels of gonadotropins, (sex) steroids, SHBG bound fractions of 17β-estradiol (E2) and testosterone (T), and sex-hormone-binding globulin (SHBG) were compared at the onset of puberty in female gymnasts (n = 7) and two groups of schoolgirls with similar anthropometric characteristics. Ten schoolgirls were matched to the gymnasts on the basis of a sum of skinfolds and the waist/hip ratio, while 12 other girls were selected on the basis of the stature and bicristal breadth of the female gymnasts. All girls were in the second stage of breast development (M2) and were classified as being in the first stage (M1) 6 months earlier.

Body fat mass, body fat distribution, and pubertal development: a longitudinal study of physical and hormonal sexual maturation of girls.

The rate at which girls progress through the stages of puberty in relation to body fat mass and body fat distribution and its relation to their hormonal profiles was studied. Sixty-eight schoolgirls participated in a longitudinal study during 3 yr. The girls were divided into subgroups with increasing skinfold thicknesses and waist-hip ratio.

Body fat distribution in pubertal girls quantified by magnetic resonance imaging.

We examined body fat distribution in relation to anthropometrically derived variables in 24 girls in early and late stages of puberty. The amounts of subcutaneous and intra-abdominal body fat were derived from transverse slices at the levels of the waist, hip and trochanter using magnetic resonance imaging (MRI), and were compared to the related circumferences, the circumference ratios and the trunk-to-extremity skinfold ratios. Waist, hip and trochanter circumferences were highly correlated to the respective related MRI total fat surface area both in early and late pubertal girls (r = 0.

Seasonal changes in performance and free testosterone: cortisol ratio of elite female rowers.

The aim of this study was to investigate the seasonal behaviour of the plasma free testosterone: cortisol ratio (FTCR) and to relate hormonal changes to daily training volume and performance parameters on a rowing ergometer in elite female rowers. During 9 months of training preceding the 1988 Olympic Games the resting values of the FTCR in six elite female rowers were regularly (ten times) studied. Daily training volume was analysed in terms of rowed distance (lrowed) and time (t).

Analysis of seasonal training volume and working capacity in elite female rowers.

Preceding the 1988 Olympic Games 6 elite female rowers were regularly subjected to an exercise test on a rowing ergometer (REM-test) with a time interval of about 5 weeks. Daily training volume was analysed in terms of rowed kilometres (RKM) and training time (TOTMIN, rowing and land training). The purpose of this study was to investigate the training volume during a season and to study possible changes in the working capacity of elite female rowers.

Dietary habits, sexual maturation, and plasma hormones in pubertal girls: a longitudinal study.

The relationships between dietary components and physical or hormonal sexual maturation in 63 pubertal girls were examined. The effects of vegetable protein and dietary fiber on breast development (B = -2.0, P less than 0.

The behaviour of the plasma free testosterone/cortisol ratio during a season of elite rowing training.

During nine months of training preceding the 1988 Olympic Games, six elite male rowers were regularly subjected to an investigation to changes in the rest values of the free testosterone/cortisol ratio (FTCR). In addition, the rowers were subjected to an exercise test on rowing ergometer. When comparing the FTCR levels through the season with the initial level, the results show that during periods of heavy training (training camp) the rest levels of the FTCR decrease (range 5-50%) in most of the rowers.

Injuries in high-risk persons and high-risk sports. A longitudinal study of 1818 school children.

In this Dutch population-based study we attempted to determine the incidence and severity of sports injuries occurring during different kind of sports in a longitudinal way. The study included 1818 school children aged 8 to 17 years. Over a period of 7 months, 399 sports injuries were reported in 324 youngsters.

Plasma lipids and apoproteins, body fat distribution and body fatness in early pubertal children.

Besides body fatness, the body fat distribution is associated with coronary risk in adults, but little has been reported on this aspect in children. This study describes body fatness, body fat distribution (waist-to-hip ratio, WHR) and the plasma lipid and apoprotein profile (TC, HDL-C, LDL-C, TG, apo A-I and apo B) in 60 boys (age 10.8 +/- 0.

[Athletic injuries in children].

Sports participation can have both beneficial and negative effects. Specific effects are injuries. The change of incidence is dependent on a number of personal and environmental factors.

[Healthy children and sports].

Sport can be considered as an excellent alternative for unhealthy consumption habits and can compensate far the outcome of a sedentary lifestyle. The youngster can improve technique, coordination and flexibility in an easy way by training programs. Specific weight training programs are not recommended for those under the age of fifteen years.

Body fat mass, body fat distribution, and plasma hormones in early puberty in females.

We examined whether there is a relationship between body fat mass or body fat distribution and hormonal profiles in the plasma of early pubertal girls. Thirty-five apparently healthy caucasian schoolgirls were selected for Tanner's breast development stage M2; they had all been classified as being stage M1 6 months earlier. Body fat mass had no relationship with the total plasma sex steroid concentration or gonadotropins.

Sex-linked variation in creatine kinase release, and its dependence on oestradiol, can be demonstrated in an in-vitro rat skeletal muscle preparation.

Creatine kinase (CK) release from male and female rat soleus muscles was studied for 4.5 h in vitro, under basal conditions and after electrical stimulation. Basal CK release was greater from male than from female muscles, and CK release from male muscles increased significantly when the muscle tension in the in-vitro set-up was increased.

Sports injuries in school-aged children. An epidemiologic study.

In November 1982, epidemiologic data were collected in a unique, large scale, population-based survey on sports injuries in school-aged children living in Holland. A total of 7,468 pupils, aged 8 to 17, completed questionnaires covering a retrospective period of 6 weeks. Seven hundred ninety-one sports injuries were registered, amounting to an incidence of 10.

Plasma lipoprotein profile in relation to sex hormones in premenarcheal athletes.

Physical activity of an endurance nature is supposed to affect the lipoprotein profile in adults as well as in children. When examining this profile in premenarcheal athletes, regard has to be paid to an interfering effect of the rising sex hormone levels due to puberty. Therefore, the purpose of this study was to investigate the plasma lipoprotein levels of premenarcheal athletes in relation to their sex hormone profile.

Nutrition of premenarcheal athletes: relation with the lipid and apolipoprotein profiles.

The lipid and apolipoprotein profiles in plasma and the nutritional intake were investigated in 25 female elite gymnasts, 23 recreational gymnasts, 21 girl swimmers, and 16 controls. The girls were matched for sexual development, assessed by means of breast development. The age of the girls varied from 10.

Renin-angiotensin system: oral contraception and exercise in healthy female subjects.

The effect of oral contraception and of exercise on the renin-angiotensin system was studied in 20 highly trained athletes, of whom 10 were ingesting oral contraceptives (users) and 10 were not (nonusers), and in 24 sedentary age-matched healthy female subjects, of whom 13 were users and 11 were nonusers. No training-related effects were observed with the exception of renin substrate, which was significantly higher in the athletes. The plasma concentrations of active renin and of trypsin-activatable prorenin were significantly lower in the subjects taking oral contraceptives.

Socio-economic factors in relation to lipid profiles in young girl athletes.

The influence of socio-economic factors on blood lipid values was studied in 4 groups of young female athletes. Based on type of sport (gymnastics and swimming) and of training intensity, the participants were subdivided into 25 talented, high achievement gymnasts (age 12.3 +/- 1.

The influence of physical exercise on growth and sexual maturation in young female rats.

This investigation deals with the influence of physical activity on the growth and sexual maturation of weanling female Wistar rats. It involves three groups of rats, namely an intensively trained group (n = 45), a moderately trained group (n = 49) and a nontrained group (n = 49). The trained groups were forced to perform physical exercise from the age of 15 days on, on a treadmill.

A retrospective growth study of female gymnasts and girl swimmers.

The aim of this investigation was to retrospectively evaluate growth patterns of different groups of gymnasts as compared to schoolgirls and girl swimmers from 1 until 11 years of age. The gymnastic groups (recreative, young talented, and older talented gymnasts) were smaller than the groups of girl swimmers and schoolgirls already from a young age on. The differences in body height between the groups of sports participants and schoolgirls in the prepubertal period appeared to be mainly based on the genetic growth regulation and seemed to be largely dependent in the gymnastic groups on inheritance of the mothers' height.