Performance training in pregnancy. Report of respiratory and cardiovascular physiologic changes in a pregnant high-performance athlete in comparison with a sample of normal pregnant patients

Abstract

Against the background of dramatic changes that took place in the history of sports during the past one hundred years, we are today discussing with regard to the compatibility of sport and pregnancy whether the extent of sports activities before pregnancy contributes to the amount of stress tolerated during pregnancy. Animal experimental studies on the effect of physical stress on the foetus cannot always be transferred to man, and hence recommendations made to pregnant women are often purely empirical. The article reports on the results of an examination of a professional woman athlete during pregnancy: Various maternal circulatory and respiratory parameters were recorded in this primigravida of 25 years of age, who had been regularly active as a competitive runner for 12 years, during the 24th week of pregnancy and from the 28th week of pregnancy onwards, at intervals of 14 days and post partum, at rest and during steady-state load on a bicycle ergometer (6 minutes each at 40 and 70 watts load, respectively) and a step-by-step load increasing every minute by 15 watts until attainment of a maternal heart rate of 150 beats per minute. The results were compared with those in a group of pregnant women who had not been competitive sportswomen. During continued training as per schedule up to the 36th week of pregnancy of the athlete, there was hardly any change in performance, and there was a marked difference against the other women. The pulse at rest was lower by a mean of 30 beats in the athlete during pregnancy, clearly indicating maintenance of the economic cardiac mechanism known to occur in trained persons, which produces a greater cardiac output via an increased stroke volume at a lower heart rate. This difference was impressively demonstrated under different loads. Another example of more economic management of an identical load is also seen, for instance, in the lower oxygen uptake and lower respiratory rate. Even at a maternal heart rate of 150 beats per minute the foetus of the athlete did not show any signs of stress under test conditions. In a measurement "at site" during the 38th week of pregnancy under routine and training conditions with relevant sprints and a maternal heart rate increase to more than 170 beats per minute, however, foetal behaviour displaying bradycardia clearly showed the existence of tolerance limits for foetal supply.(ABSTRACT TRUNCATED AT 400 WORDS)