Regular impact exercise does not cause persistent alterations in bone turnover emphasizing necessity of continuous training to achieve bone benefits. Impact exercise training lowers the serum basal PTH levels and possibly enables greater difference between the basal PTH and transient exercise-induced PTH peaks leading to osteogenic effects.

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AND SummaryThe fetal pituita.ry-adrenal axis plays an important role in the regulation of fetal development. In order to obtain information about fetal ACTH secretion at different gestational ages, a total of 109 amniotic fluid ACTH determinations was performed by ra.dioimmunoassay. There was a significantly higher level of ACTH during 26 to 30 weeks of pregnancy (4291180.4 pg/ml) than in early (208-7&90.6 pg/ml) and in late (172-7197.4 pg/ml) pregnancy; fetal sex, uterine contractions and maternal complications in pregnancy did not affect levels. The ACTH level in the first urine of six newborn infants (160.0f40.6 pg/ml) approximated to that in the amniotic fluid in late pregnancy. Our results support the assumption of a fetal origin for ACTH in amniotic fluid. The high secretion of ACTH at tht: beginning of the last trimester of pregnancy may stimulate the development of the adrenal cortex and result in the increased cortisol secretion necessary for fetal lung maturation.

Summary Plasma concentrations of ACTH (by radioimmunoassay) and cortisol (by competitive protein binding) were measured in eight healthy parturients during labour and vaginal delivery. The concentration of both ACTH and cortisol increased during labour; the maximum values were recorded immediately prior to delivery. The changes correlated well with the degree of cervical dilatation. Both the mean (±SEM) ACTH (275.3±39.5 pg./ml.) and cortisol (2.33±0.49 μmol./l.) recorded before delivery were significantly elevated compared with the initial values (ACTH: 89.3±39.5 pg./ml.; cortisol: 0.86±0.20 μmol./l.).

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