Assisted Physical Exercise and Stress in Preterm Neonates

To evaluate the markers of stress before and after a session of assisted physical exercise in infants born before 35 weeks' gestation. 25 infants born at 28(0/7) to 34(6/7) weeks were subjected to assisted physical exercise daily for about 10-15 min at one week of postnatal age or 33 weeks of post menstrual age, whichever was later. Primary outcome was salivary cortisol and secondary outcome was Premature infant pain profile (PIPP) score. Outcomes were measured, on day 5 (+/- 1) of exercise. There was no difference in salivary cortisol between baseline and immediately after (P=0.16), at 90 min (P=0.6) or 120 min (P=0.7) after exercise. Salivary cortisol was lower at 30 min after exercise as compared to baseline (mean difference -0.08 mu g/dL; 95% CI -0.16 to -0.002; P=0.04). The median (IQR) PIPP score was significantly higher at 5 min into exercise (4 (3-6) vs 4 (3-5); P=0.04) and at completion of exercise 6 (4-8) vs 4 (3-5); P < 0.01), as compared to baseline. Assisted physical exercise does not seem to result in stress in premature infants.