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We performed ergometric tests on a bicycle ergometer at the beginning and at the end of a nine month training period of track-and field athletics at school in 21 10 to 11 year old boys (8 hours training per week) and in 12 control subjects (3 1/2 hours training per week). With the exception of total work both groups had similar results at the first test. After nine months most test parameters were significantly improved in both groups. Total working time, total and maximal work, systolic blood pressure at maximal work and relative VO2max. were significantly different in the boys with 8 hours training from values obtained in the control subjects. VO2max. per kg body weight increased from a mean of 48.03 to 57.43 ml x min-1 x kg-2 (19.6%) in the boys with 8 hours training and from 44.70 tp 49.20 ml x min-1 x kg-1 (10.1%) in the control subjects. VO2-max. per kg lean body mass increased only in the boys with 8 hours training. VO2max. related to heart rate increased by 33% in the boys with 8 hours training and by 12% in the controls. The maximal minute ventilation and the minute ventilation at different submaximal working loads decreased in both groups. We conclude that the higher physical activity significantly improved the physical performance and the performance of the cardiovascular and respiratory system in preadolescent boys.

We examined the iron nutritional status of healthy term infants in a longitudinal study from 15 through 365 days of age. All infants were fed according to the present austrian recommendations. Serum hemoglobin (Hb) decreased from 15 through 122 days of age and remained constant thereafter. At 365 days of age, only 4.7% of the infants had hemoglobin levels below 11 g/dl, which is considered the borderline value for anemia. Mean corpuscular volume (MCV) of erythrocytes was changing during infancy. Free erythrocyte protoporphyrin (FEP) was constant from 122 days through 365 days of age. The upper normal value of 3 micrograms/gHb for infants older than 122 days of age corresponded to that for children older than one year and adults. Serum ferritin (SF) decreased from 15 through 183 days of age and remained constant thereafter. At 365 days of age, only 9.3% of the infants had SF below 10 micrograms/l, which is considered the borderline concentration for depletion of iron stores. We found no differences of iron nutritional status between infants who were breastfed longer than 122 days and infants who were breastfed shorter than 122 days or were fed formula. Our findings indicate that the prevalence of iron deficiency anemia and depletion of the iron stores is lower than in previous studies. Changes in infant nutrition during the last years resulted in higher iron intake and lower prevalence of iron deficiency.

We compared body composition (measured by total-body water determination), skinfolds, body circumferences and diameters and the muscle arm area of 10 to 11-year-old boys (n = 21) at the beginning and the end of a 9-months training period (track-and field athletics) with data obtained in 12 control subjects of corresponding ages. Urinary creatinine excretion was measured as a parameter of muscle mass at the end of the training period. Boys engaged in training gained (mean: + 2,6 kg) significantly less (p less than 0,05) weight than controls (mean: + 3,9 kg). Fat-free mass (FFM) as percentage of weight significantly increased in boys engaged in training (mean: + 1,8%; p less than 0,005) at the expense of fat whereas in controls (mean: + 0,6%; p: n.s.) there was no significant change. Decreasing skinfold thickness in boys engaged in training indicated reduction of subcutaneous fat. In controls, subcutaneous fat increased at the trunk and decreased at the periphery. Regression analysis indicated that changes of triceps skinfold thickness did not reflect changes in body fat content (r = 0.30; p: n.s.). A significant relation was established between changes of the subcapular skinfold thickness (r = 0,46; p less than 0,005) and of the sum of 5 skinfolds on the one hand (r = 0,51; p less than 0,005) and the changes of body fat content on the other hand. High standard deviations from the regression lines, however, indicated that accurate prediction of changes in body fat content was not possible in an individual subject.(ABSTRACT TRUNCATED AT 250 WORDS)