Regional variations in the relationship between arterial stiffness and adipocyte volume or number in obese subjects.

BACKGROUND: Cardiovascular disease is associated with multiple risk factors including stiff arteries and large adipocytes. Whether the latter two are interrelated is unknown. We aimed to determine whether arterial stiffness is associated with fat cell size and number in subcutaneous or visceral white adipose tissue (WAT). METHODS: A cross-sectional study of 120 obese subjects scheduled for bariatric surgery in whom WAT mass and distribution was assessed by dual-X-ray absorptiometry. Biopsies from visceral (greater omentum) and subcutaneous (abdominal) WAT were obtained to calculate fat cell volume and number. Arterial stiffness was determined as aortic pulse wave velocity (PWV). RESULTS: Visceral adipocyte volume, but not number, was strongly (P<0.0001) and positively correlated with PWV, explaining 20% of the inter-individual variations in this parameter. This relationship remained significant after correction for clinical confounders. PWV correlated positively (r=0.38, P<0.0001) with visceral (but not subcutaneous) WAT mass. Furthermore, PWV was also positively associated with subcutaneous adipocyte volume (r=0.20, P=0.031) and negatively with fat cell number (r=-0.26, P=0.006). However, the relationships between PWV and visceral WAT mass or subcutaneous fat cell size/number became non-significant when controlling for visceral fat cell volume. In a multiple regression analysis to determine the factors that explain variations in PWV, only visceral fat cell volume, age, pulse rate and diastolic blood pressure entered the model, together explaining 42% of the variation in PWV. CONCLUSIONS: Visceral fat cell volume was the only WAT parameter that constituted an independent and significant, positive regressor for arterial stiffness determined by PWV. Although a causal relationship is not established, visceral fat cell volume may explain the well-known correlation between central fat mass, arterial stiffness and cardiovascular risk, at least in severely/morbidly obese subjects.

Changes in hemoglobin values in elite cross-country skiers from 1987-1999.

Hemoglobin data have been available from ski teams beginning from 1987, and from 1989 to 1999 we have followed hemoglobin values in elite cross-country skiers in international competitions. The mean values at the 1989 World Nordic Ski Championships were lower than population reference values, as would be expected from plasma volume expansion associated with endurance training. However, an increase, particularly in the maximal values, became obvious in 1994 and rose further in 1996. These extreme values provide both a health risk to the individual athlete and unfair competition. After a rule limiting hemoglobin values was introduced, the drop of the highest values was remarkable: among men 15 g/l (0.23 mmol/l) and among women 42 g/l (0.65 mmol/l). It would appear that the rule had achieved its goal of limiting extreme hemoglobin values. Yet the mean hemoglobin concentrations in men and women have continued to rise, suggesting the continued use of artificial methods to increase total hemoglobin mass.

Nasal administration of immunoglobulin as effective prophylaxis against infections in elite cross-country skiers.

15 elite skiers (Swedish olympic team) taking part in the games in Alberville were prophylactically treated with nasal administration of immunoglobulin, mainly IgA. Team coaches served as controls. No infections occurred in the treated group, whereas 9/19 of the coaches developed symptoms of infection. These results suggest that nasal administration of antibodies significantly reduces the incidence of upper respiratory tract infections in elite skiers and may serve as a valuable short-term physiological prophylaxis in the prevention of disease.

Cortisol and androgen concentrations in female and male elite endurance athletes in relation to physical activity.

To evaluate the effect of variations in physical activity on selected hormone concentrations in male versus female athletes, fasting serum concentrations of cortisol (C), total-testosterone, free-testosterone, non sex hormone binding globulin (SHBG) bound testosterone, dehydroepiandrosterone, 4-androstene-3,17-dione and SHBG were studied. The tests were performed in nine male and seven female elite endurance athletes during the off-season (test 1), early in the competition season (test 2) and at the end of the competition season (test 3). The C concentration increased significantly during the competition season in women but not in men. Further, the mean C concentrations at test 3 as well as the mean level during the whole observation period (tests 1, 2, 3) were significantly higher in women than in men. No significant changes were found in androgen concentrations or androgen:cortisol ratios within the two groups. The differences between the sexes in C response may indicate different adaptive mechanisms to similar physical stress.

Endogenous anabolic and catabolic steroid hormones in male and female athletes during off season.

Peripheral serum hormone levels during the off season were analysed in 10 male and 10 female athletes, all belonging to the Swedish national teams in skiing and orienteering and in age matched sedentary controls (15 males, 13 females). No clinical signs of overuse strain were observed in any of the athletes. No significant differences in hormone variables were found between male athletes and controls. The female athletes had significantly higher levels of cortisol and significantly lower ratios between total testosterone and cortisol, between non-SHBG-bound testosterone and cortisol and between 4-androstene-3, 17-dione and cortisol than the sedentary controls. The increased levels of cortisol found in the female athletes probably reflect an adaptation to several years of hard training. A decrease of the free T/cortisol ratio has earlier been shown to indicate an overuse distress. One may speculate that the low androgen/cortisol ratios found in the female athletes in contrast to the males could indicate that the female athletes might need longer time to recover from hard exercise than male athletes, or could suggest an insufficient dietary intake.

Serum erythropoietin in cross-country skiers.

Serum erythropoietin concentration and hemoglobin concentration were determined during the winter season in 41 male and 31 female well-trained, cross-country skiers. The athletes both lived and trained at low altitude (below 300 m above sea level). No significant differences in serum erythropoietin concentration were seen between male skiers (13.6 +/- 5.0 mU.ml-1), female skiers, (14.9 +/- 5.6 mU.ml-1), and normal controls (12.6 +/- 3.9 mU.ml-1) (mean +/- SD). In 18 of the skiers (12 males and 6 females), a second sample was taken after 2.3 +/- 0.18 months. No significant difference in either serum erythropoietin concentration or hemoglobin concentration was detected between the two samples in this combined group of skiers. The present study indicates that normal serum erythropoietin concentration is to be expected during the winter season at sea level in cross-country skiers living and training at low altitude.

Detection of autologous blood transfusions in cross-country skiers.

Transfusion of autologous blood (blood doping) has been used by athletes to improve performance in sports events. This practice has been banned by the International Ski Federation (FIS) and the International Olympic Committee (IOC). So far, no reliable method for detection of blood doping has been available. In the present study, a group of six elite cross-country skiers, who were phlebotomized and retransfused with 1350 ml of blood 4 weeks later, was compared with a control group (n = 7) in whom no blood doping was performed. The blood was stored at +4 degrees C for 4 weeks. Hemoglobin increased by 7.9% from the prephlebotomy level and by 14% from the preinfusion level. The reinfusion of blood caused a 60% reduction (P less than 0.001) in serum erythropoietin in 24 h and a sharp increase (P less than 0.05) in serum iron and bilirubin after a test race performed on the day of reinfusion. It is therefore concluded that a combination of measurements of hemoglobin and bilirubin, iron, and erythropoietin in serum could detect 50% of the blood-doped athletes by a single test sample during the 1st week after reinfusion. If two test samples were used, an increase in Hb of more than 5%, and a decrease in serum erythropoietin by more than 50%, would be discussed in 50% of the blood-doped athletes throughout the first 2 weeks after reinfusion and without implicating any of the controls.

Effects of caffeine ingestion on exercise performance at low and high altitudes in cross-country skiers.

The effect of caffeine on exercise time over a specified distance (approx. 21 km) was investigated in well-trained cross-country skiers (14 subjects) both at low (300 m above sea level) and high (2900 m above sea level) altitudes. Each subject participated in two races at both altitudes--one after caffeine ingestion (6 mg/kg body weight) and one after placebo on a double-blind basis. In each race 50% of the participants were medicated with caffeine, thereby after normalization (where the mean time was set at 100%), when the influence of weather and snow conditions were minimized, the difference between the race time with caffeine and placebo could be calculated for each individual and expressed as a percentage of the mean. At low altitudes, after half the distance, the race time with caffeine was decreased 0.94% of the mean time (corresponding to approx. 33 s) as compared to placebo (P less than 0.05), whereas after the full distance the corresponding decrease was 1.7% of the mean time (corresponding to approx. 59 s) (0.05 less than P less than 0.10). At high altitudes, the race time was significantly faster with caffeine than with placebo (P less than 0.001), both after one and two laps, 2.19% and 3.18% of the mean time, respectively (corresponding to approx. 101 s and 152 s). The perceived exertion was similar at low and high altitudes independent of medication. In conclusion, there are indications that caffeine induces an increased performance capacity for cross-country skiers at low altitudes. Furthermore, an even more marked improvement after caffeine as compared to placebo was found at high altitudes.