Comparing The Physiological Responses To Cycle And Treadmill Exercise Between Preterm-born And Term-born Adults

PURPOSE: People born preterm (<37 weeks’ gestation) have lower peak oxygen consumption (peak VO2), a well-established indicator of long-term health outcomes, compared to term-born peers. However, responses to exercise can vary with exercise mode, which has implications for prognostic assessments. No studies have investigated how physiological responses vary with different exercise modes in preterm- versus term-born individuals. This study compared treadmill and cycle ergometry cardiopulmonary exercise test (CPET) outcomes between preterm- and term-born adults. METHODS: Adults born ≤32 weeks’ gestation and term-born adults completed two maximal CPETs using cycle ergometry (Ramp) and a treadmill (Modified Balke) on separate visits, at least 3 days apart. VO2, work rate (WR), heart rate (HR), oxygen pulse (O2P), minute ventilation (VE), tidal volume (Vt), and breathing frequency (fb) were measured at peak exercise. Differences (%) in CPET measurements between mode were compared between term and preterm groups using Mann-Whitney U tests. Significance was set as p ≤ 0.05. RESULTS: 22 preterm-born (mean gestation: 27 weeks, IQR: 24, 30; mean age: 24 years ± SD: 1.5) and 5 term-born (age: 23 ± 1.7 years) adults were tested. For adults born preterm, peak VO2 was higher in CPETs by treadmill (19%) compared with cycle ergometry. Cardiac parameters at peak exercise were also higher in treadmill than cycle ergometer tests (HR: 4%; O2P: 13%). No significant differences were seen for WR, VE, fb, or Vt. The differences in peak outcomes with exercise mode were not significantly different between the term and preterm groups (Table 1) . CONCLUSIONS: Differences between cycle ergometry and treadmill exercise responses were similar between term- and preterm-born individuals. Similar to term-born individuals, CPETs using cycle ergometry can underestimate peak VO2. This should be considered when interpreting assessments of exercise capacity in preterm-born individuals. Supported by: Curtin Strategic PhD Scholarship; Wal-yan Respiratory Research Centre PhD Top-up Scholarship; Western Australia Child Health Research Fund (WACRF)