Blunted cardiac output response to exercise in adolescents born preterm.

Purpose: Premature birth is associated with lasting effects, including lower exercise capacity and pulmonary function, and is acknowledged as a risk factor for cardiovascular disease. The aim was to evaluate factors affecting exercise capacity in adolescents born preterm, including the cardiovascular and pulmonary responses to exercise, activity level and strength.
Methods: 21 preterm-born and 20 term-born adolescents (age 12-14 years) underwent strength and maximal exercise testing with thoracic bioimpedance monitoring. Baseline variables were compared between groups and ANCOVA was used to compare heart rate, cardiac output (Q) and stroke volume (SV) during exercise between groups while adjusting for body surface area.
Results: Preterm-borns had lower maximal aerobic capacity than term-borns (2.0 ± 0.5 vs. 2.5 ± 0.5 L/min, p = 0.01) and lower maximal power (124 ± 26 vs. 153 ± 33 watts, p < 0.01), despite similar physical activity scores. Pulmonary function and muscular strength did not differ significantly. Although baseline Q and SV did not differ between groups, preterm adolescents had significantly lower cardiac index (Qi) at 50, 75 and 100% of maximal time to exhaustion, driven by SV volume index (SVi, 50% max time: 53.0 ± 9.0 vs. 61.6 ± 11.4; 75%: 51.7 ± 8.4 vs. 64.3 ± 11.1; 100%: 51.2 ± 9.3 vs. 64.3 ± 11.5 ml/m ² , all p < 0.01), with similar heart rates.
Conclusion: Otherwise healthy and physically active adolescents born very preterm exhibit lower exercise capacity than term-born adolescents. Despite similar baseline cardiovascular values, preterm-born adolescents demonstrate significantly reduced Qi and SVi during incremental and maximal exercise.