Insulin secretion in normal glucose-tolerant relatives of type 2 diabetic subjects. Assessments using hyperglycemic glucose clamps and oral glucose tolerance tests.

OBJECTIVE: To assess insulin secretion in normal glucose-tolerant Caucasian first-degree relatives of type 2 diabetes subjects and in matched normal glucose-tolerant control subjects and to compare insulin secretion as assessed using a hyperglycemic glucose clamp with insulin secretion as assessed using an oral glucose tolerance test (OGTT). RESEARCH DESIGN AND METHODS: Twenty-one first-degree relatives of type 2 diabetic subjects and 21 control subjects without a family history of type 2 diabetes, who were matched for sex, age, BMI, waist-to-hip ratio, and aerobic capacity, underwent a hyperglycemic glucose clamp (10 mmol/l, 180 min). An OGTT (75 g glucose in 300 ml water) was also performed. RESULTS: First-phase insulin release (plasma insulin, 0-10 min) was not different (multiple analysis of variance [MANOVA]: F = 2.63, P = 0.11). Second-phase insulin release was lower (MANOVA: F = 4.18, P = 0.047). Separate analyses of variance showed decreased plasma insulin levels from 120 min onward (all P < 0.05), decreasing to geometric mean (95% CI) levels of 330 (270-402) and 462 (366-582) pmol/l at 180 min in relatives and control subjects, respectively. The insulin sensitivity index (ISI) as assessed using a hyperglycemic clamp was not different between the two groups. Mean +/- SE ISI during the 3rd hour was 27.5 +/- 2.2 and 30.5 +/- 3.0 micrograms.kg-1.min-1.pmol-1.l-1 in relatives and control subjects, respectively (P > 0.20). At 90 min after the OGTT, log plasma insulin levels correlated significantly with second-phase insulin release as assessed using the hyperglycemic glucose clamp. CONCLUSIONS: Normal glucose-tolerant first-degree relatives of type 2 diabetic subjects have a decreased second-phase insulin release, compared with matched control subjects. After an OGTT, 90-min values of log plasma insulin and 90-min values of the ratio of log plasma insulin to blood glucose may be good indicators of insulin secretory properties in normal glucose-tolerant family members of type 2 diabetic subjects.

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. They were also grouped depending on Tanner's breast development classification (M2 and M3). The age at M2 was only marginally correlated with the menarcheal age, but the age at M2 and the time interval from that age to menarche was negatively correlated. Age at the onset of puberty was not related to body fat mass or distribution. The rate of pubertal development after pubertal stage M3 was negatively related to the body fat mass. Age at M2 was only correlated with estrone (E1), while the rate of pubertal development was associated with higher FSH, E1, estradiol (E2), the fraction of E2 that was not bound to sex-hormone-binding globulin (non-sex-hormone-binding globulin bound E2) and androstenedione plasma levels at the onset of puberty. Body fat distribution, rather than body fat mass was related to the total and the non-sex-hormone-binding globulin bound plasma levels of E2 and testosterone at the onset of puberty. Changes in body fat distribution in early female puberty were chiefly related to the waist circumferences. We found no evidence that body fat mass or body fat distribution triggers the onset of puberty. Body fat distribution was related to early pubertal endocrine activity. Body fat mass was negatively related to the rate of pubertal development toward menarche, but no clear indications for an endocrine-related process is found. We conclude that onset of puberty and menarche are not parallel pubertal events, and that early pubertal plasma E1, E2 and androstenedione levels are predictors for the rate of pubertal development toward menarche. We propose that the control of the onset of puberty and maturation of the hypothalamic-pituitary gonadal axis, with regard to negative feedback control, are at least partially independent. This induces on the average a "catch up" pubertal maturation in girls with a late onset of puberty.

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. However, body fat mass was correlated with the fraction of testosterone that was not bound to sex hormone-binding globulin and considered the fraction available for biological activity. Body fat distribution, rather than body fat mass, was different in relation to the total concentrations of estrone, estradiol (E2), and testosterone as well as the percentage of available E2 or testosterone. Girls with fat localized predominantly on the hips had the highest levels of sex steroids and gonadotropins. It seems likely that this type of fat distribution is a result of ovarian activity. Girls with predominantly abdominal fat were also more obese and showed increased plasma levels of total E2 and a lower androgen/estrogen ratio in plasma, possibly due to increased aromatization, especially in abdominal adipose tissue. The findings suggest a reciprocal relationship among body fat distribution, plasma sex hormone levels, and availability of sex steroids in early female puberty.

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 0.05; B = -2.6, P less than 0.05, respectively) became more pronounced in a multivariate analysis, after elimination of the linear effects of body height and energy intake. From the multivariate analysis with combinations of vegetable protein, polysaccharides, and fiber in the equation, fiber appeared to be the most important factor. The gonadotropin and estradiol plasma concentrations were higher in girls who consumed less grain fiber. We conclude that a diet rich in vegetable products, especially fiber, may affect the rate of physical and hormonal sexual maturation, possibly mediated by the hypothalamus-pituitary-gonad system.

Resting metabolic rate, body composition and related hormonal parameters in growth hormone-deficient adults before and after growth hormone replacement therapy.

The resting metabolic rate (RMR), and body composition were assessed in 30 growth hormone-deficient (GHD) adults before and after 3 and 6 months of replacement therapy with recombinant human growth hormone (rhGH). In addition, insulin-like growth factor I (IGF-I), IGF binding proteins (IGFBPs) and plasma insulin were measured at baseline and at 6 months in relation to RMR. During 6 months of rhGH replacement therapy, body fat decreased from 18.2 +/- 1.5 (mean +/- SEM) to 14.3 +/- 1.6 kg (p < 0.0001), whereas fat-free mass (FFM) increased from 53.5 +/- 3.3 to 56.3 +/- 3.6 kg (p < 0.0001), RMR increased from 1246 +/- 92 to 1539 +/- 102 kcal/24 h (p < 0.0001) and RMR per kilogram of FFM increased from 23.2 +/- 0.6 to 27.4 +/- 0.5 (p < 0.0001). When RMR data were adjusted for the differences in FFM, it appeared that apart from the increase in FFM, other factors may play a role in the increase in RMR. During rhGH replacement therapy, IGF-I (p < 0.0001) and IGFBP-3 (p = 0.003) levels increased, whereas IGFBP-1 levels decreased significantly (p = 0.004). The FFM explained for about 80% of the variance in RMR. In addition, waist/hip ratio and plasma IGF-I contributed significantly to the explained variance of RMR. This study shows that in GHD adults FFM is the main determinant of RMR and that, next to the increase in FFM, changes in metabolic and hormonal parameters contribute to the increase in RMR during rhGH replacement therapy.

Determinants of insulin sensitivity in chronic heart failure.

OBJECTIVE: To describe the determinants of insulin sensitivity (IS) in chronic heart failure (CHF), we created a model in which the influence of lifestyle factors and etiology of heart failure on IS were incorporated concomitantly with age, left ventricular ejection fraction (LVEF) and parameters of body composition. DESIGN: Observational cohort study. SETTING: Outpatient clinic for chronic heart failure. PATIENTS: Fifty-seven male CHF patients [NYHA class II-III, age 61+/-9 years, body mass index (BMI) 26.9+/-3.3 kg/m2 (mean+/-S.D.)]. INTERVENTIONS: Euglycemic hyperinsulinemic clamp, cycle ergometry, anthropometric measurements, LVEF and a physical activity questionnaire. MAIN OUTCOME MEASURES: A model explaining the variance of IS in CHF. RESULTS: IS was 18.2+/-8.6 microg.kg(-1).min(-1).mU(-1).l(-1), fasting insulin level was 15.9+/-11.0 mU/l and fasting glucose level was 5.5+/-0.6 mmol/l. Peak VO2 was 19.1+/-4.9 ml.kg(-1).min(-1) and LVEF 26.2+/-7.1%. IS was inversely associated with fasting insulin concentration (r=-0.50, P<0.001) and BMI (r=-0.54, P<0.001). After controlling for BMI, IS also revealed a correlation with age (r=-0.36, P<0.01). The model explained 60% of variance in IS: BMI contributed 20%, smoking 17%, age 17% and physical activity in daily life (DPA) 16% (all P<0.05) to the variance of IS, whereas LVEF (9%) and etiology of heart failure (8%) contributed moderately. CONCLUSIONS: In CHF patients, IS is for a major part predicted by BMI, smoking, age, daily physical activity, LVEF and etiology of heart failure.

Lower beta-cell secretion in physically active first-degree relatives of type 2 diabetes patients.

Regular physical activity may prevent or postpone type 2 diabetes, and is thought to be related to an increase of insulin sensitivity. We studied whether physically active, glucose-tolerant first-degree relatives of type 2 diabetes patients differ in glucose tolerance (oral glucose tolerance test [OGTT]) and insulin secretion (hyperglycemic glucose clamp) from less active first-degree relatives. A group of 37 relatives was split into 2 subgroups according to the sex-specific median of the sports index, assessed by a questionnaire, as the cutoff point. Blood glucose levels during the OGTT were lower in the highly active subgroup versus the less active counterparts (multivariate ANOVA [MANOVA], P = .011), but the plasma insulin levels were similar. First-phase secretion was not different in the highly active group versus the less active group, but second-phase secretion (average plasma insulin in the third hour) was significantly lower (P = .016). As expected, the insulin sensitivity index (ISI) was higher in the highly active subgroup (P= .011). Subdivision into subgroups with high or low maximal O2 consumption (VO2max) resulted in similar differences, but these were not significant. In a group of 21 controls, the results resembled the values in the relatives but were less often statistically significant. In conclusion, regular physical activity not only is associated with increased insulin sensitivity but also downregulates the pancreatic beta cell. This downregulation may provide an extra mechanism by which physical activity diminishes the development of type 2 diabetes.

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 ± 0.6 years (mean ± S.D.), participated in the study. During a 3 year follow-up, the following measurements were taken twice a year: stature, weight, and skinfolds. Blood samples for lipids and apoproteins and sex hormone levels, and information on participation in sport activities were also obtained. No relationship was found between participation in organized sport activities and high density lipoprotein cholesterol (HDL-C) or apoprotein A-I (apo A-I). The changes of the profile over time in more active boys (participation rate > 3 hr/wk) were similar to those of less active boys (participation rate < 1 hr/wk) (MANOVA, repeated measures, not significant.) Consistent relationships between sex hormones and lipids and apoproteins were restricted to T with total cholesterol (TC), HDL-C, and apo A-I, respectively. The common variance ranged from 5.8% (rT,TC ) to 18.5% (rT,HDL-C ) (P ⩽ 0.05.) When the boys who reached advanced puberty during the follow-up period (n = 21) were studied apart from those who did not (n =29), differences were found in TC, apo A-I, and HDL-C, TC decreased from 4.6 ± 0.65 to 4.3 ± 0.58 mmol/l in the more advanced pubertal boys, and increased from 4.6 ± 0.90 to 4.8 ± 0.79 mmol/l in the others; apo A-I decreased from 185 ± to 28.3 to 156 ± 20.4 mg/dl and from 179 ± 20.6 to 176 ± 27.7 mg/dl, respectively (MANOVA, repeated measures, P ⩽ 0.05) HDL-C was lower in advanced pubertal boys at the end of follow-up (1.4 ± 0.33 and 1.7 ± 0.38 mmol/l, respectivel; P ⩽ 0.05). The lack of a relationship with regular physical activity may be due to the high levels of HDL-C and apo A-I at the begining of the study. On the other hand, the effect of the increasing T levels on HDL-C and apo A-I may have overwhelmed the presumed effect of regular physical activitiy. © 1995 Wiley-Liss, Inc.

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

Plasma levels of gonadotropins, (sex) steroids, SHBG bound fractions of 17ß-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. When female gymnasts were compared to nonathletic schoolgirls with similar physical characteristics at the same stage of early puberty, the former had significantly lower levels of plasma luteinizing hormone (LH), total and available E2, and T. In conclusion, female gymnasts have significantly lower LH, E2, and T plasma levels than nonathletic schoolgirls in early puberty. The E2 and T plasma levels in early female gymnasts are not related to the individual physical characteristics, i.e., fat mass, short stature, or small bicristal breadth. © 1993 Wiley-Liss, Inc.

Relationships between testosterone, cortisol and performance in professional cyclists.

In the literature the use of plasma levels of cortisol and the testosterone and testosterone: cortisol ratio for training management is encouraged. Decreased levels of testosterone and increased levels of cortisol are suggested to be indicative for a disturbance in the anabolic-catabolic balance, which may express itself in decreased performance. The purpose of the study was to examine if the acute hormonal response to a bout of exercise and the resting levels of testosterone, luteinizing hormone (LH) and cortisol are correlated to performance in cyclists. In addition, the effect of training on this correlation was studied. Ten professional cyclists participated and measurements took place before and after a defined period of training. Maximum workload (Pmax), determined on a cycle-ergometer with a slowly increasing protocol, increased by 30 watt (p < 0.001). Workload at a lactate level of 4 mmol/l (P4) increased by 18 watt (p < 0.05). Post training, resting testosterone levels decreased from 28.8 +/- 74 nmol/l to 24.6 +/- 90 nmol/l (p < 0.05). Resting cortisol levels increased from 272 +/- 110 nmol/l pre training to 379 +/- 242 nmol/l post training (p < 0.05). These results indicate an increased catabolic state. The acute hormonal response and the resting levels of LH were not changed post training. The resting levels of testosterone and cortisol and the acute response to exercise showed no correlation with performance pre and post training. In spite of an increased catabolic state post training there was an increase in performance. These results suggest that in endurance trained cyclists, decreased testosterone levels, increased cortisol levels and a decreased testosterone: cortisol ratio does not automatically lead to a decrease in performance or a state of overtraining.

Effects of physical training on metabolic control in elderly type 2 diabetes mellitus patients.

1. The specific role of physical activity in the treatment of type 2 diabetes is still subject to discussion. A randomized prospective study was performed, investigating both the influence of physical training on metabolic control and the feasibility of physical training in the elderly. 2. A total of 58 patients (mean age: 62 +/- 5 years; range: 55-75 years) with type 2 diabetes were randomized to either a physical training or a control programme. The training programme consisted of three sessions a week, aiming at 60-80% of the maximal oxygen uptake (VO2max). The 12 week supervised period was followed by a 14 week non-supervised one. The control group followed an educational programme. VO2max was assessed during exercise on a cycle ergometer. Glycosylated haemoglobin (HbA1c) was used as a measure for glucose control, and an insulin tolerance test was performed to test insulin sensitivity. Multivariate analysis of variance, with repeated measures design, was used to test differences between groups. 3. Fifty-one patients completed the study. VO2max was higher in the training group than in the control group both after 6 weeks (P < or = 0.01 between groups) and after 26 weeks [training group: 1796 +/- 419 ml/min (prestudy), 1880 +/- 458 ml/min (6 weeks), 1786 +/- 591 ml/min (26 weeks); control group: 1859 +/- 455 ml/min (prestudy), 1742 +/- 467 ml/min (6 weeks), 1629 +/- 504 ml/min (26 weeks)]. Blood glucose control and insulin sensitivity did not change during the study. Levels of total triacylglycerols, very-low-density lipoprotein-triacylglycerols and apolipoprotein B were significantly lower after 6 weeks (P < or = 0.01, P < or = 0.05, P < or = 0.05 between groups respectively), and so was the level of total cholesterol after 12 weeks of training (P < or = 0.05 between groups). 4. Physical training in obese type 2 diabetic patients over 55 years of age does not change glycaemic control or insulin sensitivity in the short-term. Regular physical activity may lower triacylglycerol and cholesterol levels in this group of patients. 5. Finally, physical training in motivated elderly type 2 diabetic patients without major cardiovascular or musculoskeletal disorders is feasible, but only under supervision.

Height, body composition, biological maturation and training in relation to socio-economic status in girl gymnasts, swimmers, and controls.

This study examined the height, body composition, prevalence of obesity, biological maturation and training in relation to socio-economic status of 78 female gymnasts (age 138 +/- 18 months), 52 girl swimmers (age 134 +/- 24 months) and 116 control girls (age 131 +/- 21 months). The female gymnasts are shorter and lighter than girl swimmers. They are also shorter than control girls comparing the growth percentiles. The weight to height ratio (w/h) and the Quetelet index are the same for the groups. The female gymnasts have less fat, and a later biological maturation than girl swimmers and controls. The socio-economic status of girl swimmers is lower than that of the control group. Nevertheless the girl swimmers are taller and they have the same biological maturation as the controls. The girl swimmers are even more matured than the gymnasts. The gymnasts have the same socio-economic status as the controls, but they are shorter and less matured. Therefore, in the investigated groups no positive relationship between height and socio-economic status exists. Nor is a low socio-economic status accompanied by a late biological maturation or a higher prevalence of obesity. Training did not correlate with socio-economic status in gymnasts or controls, only in the swimming group a weak correlation was found.

Different metabolic adaptation of heart and skeletal muscles to moderate-intensity treadmill training in the rat.

The effect was investigated of treadmill training of moderate intensity on the fatty acid-binding protein (FABP) content in relation to parameters of oxidative and glycolytic metabolism. To this end, the cytoplasmic FABP content and the activity of beta-hydroxyacyl-coenzyme A dehydrogenase (HAD), citrate synthase (CS), and 6-phosphofructokinase (PFK) were measured in heart, fast-twitch extensor digitorum longus (EDL) and slow-twitch soleus muscles (SOL) of male Wistar rats. To investigate the influence of the amount of training (defined as the product of exercise duration, intensity and frequency), two training groups were created that differed in training frequency (HF, high frequency 5 days x week(-1), n = 9; LF, low frequency 2 days x week(-1), n = 9; the exercise being 20 m x min(-1) for 2 h with no gradient, over 6 weeks) and compared with SC, sedentary controls (n = 7). In heart muscle, the cytoplasmic FABP content was 34% higher in HF than in SC but was the same as in LF. The CS and HAD activities were no different in the three groups, suggesting that the capacity to oxidize fatty acids (FA) was not affected by training. The PFK activity was higher (43%) in HF, suggesting a shift towards carbohydrate utilization. The FABP content and HAD activity did not change in SOL and EDL after training whereas the CS activity increased (27%) in SOL and decreased (21%) in EDL in both training groups. In addition, PFK activity in EDL was much higher (113%) in the HF than in SC group. The HF training was associated with a fine-tuning of FA availability and use in heart muscle, and with a more efficient energy production. It is suggested therefore that cytoplasmic FABP could be an early marker of muscle adaptation to training in heart but not in skeletal muscle. The training reinforced the metabolic profile of the skeletal muscles, in particular that of the fast-twitch glycolytic muscle. We concluded that a large amount of training is needed when the effect on both oxidative and glycolytic parameters is to be studied.

Apolipoprotein and lipid profiles in young female athletes.

The apolipoprotein and lipid profiles were investigated in 22 female gymnasts, 20 girl swimmers, and 12 controls. The average age of all groups was about 12 years, and the girls were matched for sexual development, i.e., breast development stage m = 1 or m = 2. The gymnasts appeared to have the highest level of HDL cholesterol and the highest HDL cholesterol / total cholesterol, HDL cholesterol / LDL cholesterol and HDL cholesterol/apo A-I ratios in comparison to both the swimmers and the control group. The swimmers had the highest level of apo A-I, but a lipid profile similar to that of the controls. It is concluded that in children, as in adults, regular physical activity affects the lipid and apolipoprotein profiles. In addition, it appears that the apolipoproteins discriminate between trained and nontrained subjects as well as (apo B) or better (apo A-I) than the lipid components of the corresponding lipoproteins (LDL cholesterol or HDL cholesterol).

Response to exercise of patients with idiopathic hyper-CK-emia.

Patients with an idiopathic increase in serum creatine kinase (CK) levels (hyper-CK-emia) have a benign prognosis, but symptoms may be disabling in daily life. Previous studies have suggested that physical exercise increases the severity of complaints in these patients. We studied whether maximal and submaximal bouts of exercise on a cycle ergometer are harmful for patients with idiopathic hyper-CK-emia. Such dynamic exercise did not lead to larger increases in serum CK activity or more complaints in 11 patients with idiopathic hyper-CK-emia, compared with 11 age-matched healthy controls. Our data suggest that exercise does not result in more extensive muscle damage in patients with idiopathic hyper-CK-emia than in healthy subjects.

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 +/- 1.6 (SD) year), 42 non-talented, low achievement gymnasts (age 12.0 +/- 1.2 (SD) year), 12 high achievement swimmers (age 10.3 +/- 1.6 (SD) year), and 24 low achievement swimmers (age 10.8 +/- 1.6 (SD) year). With respect to socio-economic factors, no significant differences were observed between the two gymnastic groups nor between the two swimming groups. The blood lipid values revealed a significantly higher low density lipoprotein-cholesterol level and significantly lower high density lipoprotein-cholesterol/total cholesterol and high density lipoprotein-cholesterol/low density lipoprotein cholesterol ratios in the talented gymnasts as compared to the non-talented gymnasts. In the high achievement swimmers, low density lipoprotein-cholesterol and triglyceride levels were significantly lower and high density lipoprotein-cholesterol/total cholesterol was significantly higher as compared to the other swimmers. The Spearman rank order correlation coefficients for the relationships between socio-economic factors and blood lipid values were mostly weak or inconsistent. Therefore, no major influence of socio-economic factors on blood lipid values could be demonstrated in the groups investigated.

Biological maturation, body composition, and growth of female gymnasts and control groups of schoolgirls and girl swimmers, aged 8 to 14 years: a cross-sectional survey of 1064 girls.

The aim of this study was primarily to investigate differences in onset and progression of puberty, body composition, and growth between groups of young female gymnasts, schoolgirls and girl swimmers, and secondly to determine the relations between the pubertal events and body composition, especially the amount of body fat, or training activities. In 1980, 1981, and 1982, 668 female gymnasts, 298 schoolgirls and 98 girl swimmers were examined. The gymnasts were subdivided into three different groups, namely, the talented, the nontalented, and the selection group. The onset of puberty and menarche was delayed in the gymnastic groups by about 1 or 2 years compared to the schoolgirls and girl swimmers. The gymnasts were on average smaller than the schoolgirls and girl swimmers. These differences became even more pronounced after the age of 10 years. This may be caused by a delayed growth spurt within the gymnastic groups in combination with self-selection. Furthermore, the gymnasts were leaner than the other two groups: the girl swimmers had a greater fat mass and a greater lean body weight, while the schoolgirls had more fat mass. Relations were found between the parameters of pubertal development and calculated fat mass and also between breast development, pubic hair growth and age, body height, body weight, and calculated lean body weight. Only in the swimming group were training hours per week related to body height, body weight, lean body weight, and pubic hair growth.

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. Thirty-six elite gymnasts, 21 recreational gymnasts, 27 girl swimmers, and 25 very little active control girls participated. Their age was about 12 years. The sex hormone profiles of all groups were similar. The swimmers had the lowest level of TC, LDL-C, and TG (P less than or equal to 0.05), and apo A-I was elevated in this group as compared with the others (P less than or equal to 0.05). HDL-C was highest in the recreational gymnasts (P less than or equal to 0.05). The elite group and the control group had similar lipoprotein profiles. After adjustment for T and E-2, no change in variance of the lipoproteins was found. A low correlation existed between apo A-I, E-2, and T (P less than or equal to 0.05). Thus, in this pediatric population, the sex hormones did not play a significant role relative to the levels of plasma lipids or apo A-I. As the body composition correlated very weakly with TG, it is tentative to conclude that the variance found in the lipoprotein profile might be due to differences in physical activity. Moreover, genetic factors may have contributed to the variance.

Endothelial markers in chronic heart failure: training normalizes exercise-induced vWF release.

BACKGROUND: Chronic heart failure (CHF) is characterized by endothelial dysfunction. Vascular endothelium is important for control of haemostasis and vasoregulation. The aim of the present study was to investigate plasma levels of several endothelial markers and the exercise-induced changes on these plasma levels in CHF patients. Subsequently, the effect of a 6-month training programme on these markers is described. MATERIALS AND METHODS: Twenty-nine male CHF patients (NYHA II/III, age 60 +/- 8 year, body mass index 26.7 +/- 2.3 kg m(-2), left ventricular ejection fraction 26.3-7.2%; mean +/- SD) participated. Patients were randomly assigned to a training or control group. Training (26 weeks; combined strength and endurance exercises) was four sessions/week: two sessions supervised and two sessions at home. Before and after intervention, anthropometry, endothelial markers (haemostasis and vasoregulation), maximal workload and peak oxygen uptake were assessed. RESULTS: Physical training positively affected maximal workload. Plasma levels of endothelial markers were not affected by physical training and not related to exercise tolerance. After training, stimulated (maximal exercise) plasma von Willebrand Factor (vWF) release was present, whereas at baseline this release was absent. CONCLUSION: Physical training led to normalization of the stimulated plasma vWF release. Plasma levels of other endothelial markers were not affected by physical training either at rest or under stimulated (maximal exercise) conditions.

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. Significant differences existed in weight as percentage of normal weight for height between the gymnasts and the swimmers. No relations existed between the standard deviation scores, weight percentage, and socioeconomic status. Contrary to general belief, there was no evidence that physical activity from a young age on directly influences growth until puberty.