Aerobic Interval Training Breathing 100% O2 Improves VO2peak Equally as Ambient Air Training in Coronary Patients

Abstract

Elevated aerobic exercise capacity is vital in reducing mortality in both healthy individuals and cardiac heart failure (CAD) patients. High intensity aerobic interval exercise has been shown to be superior to moderate intensity exercise, for increasing aerobic capacity in CAD patients. Further research is needed for perfecting training protocols for this patient group. PURPOSE: The purpose of this study was to investigate if breathing 100% oxygen gas during aerobic interval training in CAD patients improves the quality of training compared to aerobic interval training in ambient air. METHODS: Ten stable CAD patients were recruited to an oxygen training group (OTG). Age: 61.1 ± 7.1 years, Height: 175.5± 11.1 cm, Body Mass: 82.3 ± 13.2 kg. Patients underwent 10 weeks of supervised interval training, with inclined treadmill walking 4x4 minutes, 3 times a week, breathing 100% oxygen gas. Training intensity was set to 80–90% of peak oxygen uptake (VO2peak). An ambient air control training group (ATG) of 11 CAD patients completed the same training regime at a later time point. Several tests were completed before and after the training period, including VO2peak measured in ambient air and while breathing 65% O2, peak cardiac output (QCpeak), peak stroke volume (SVpeak), and blood volume measured by the Evans Blue Dye technique. Nonparametric statistic test were used. RESULLS: VO2peak increased significantly in the OTG and ATG by respectively 15.6% from 25.9 ± 4.2 to 29.9 ± 3.9 ml*kg-1*ml−1, and 9.2 % from 28.6 ± 4.4 to 31.4 ± 5.2 ml*kg-1'min−1 (p< 0.05). VO2peak measured while breathing 65% O2 in the OTG increased significantly by 16.4 % from 25.3 ± 4.0 to 29.7 ± 4.0 ml*kg-1'min−1 (p< 0.05). QCpeak increased significantly by 24.3% from 11.1 ± 2.1 to 13.8 ± 2.8 l*min−1 and by 11.9%, from 11.9 ± 3.2 to 13.6 ± 3.2 mm1 (p< 0.05) in the OTG and ATG respectively. SV eak increased significantly in the OTG and ATG by 13.3% from 99 ± 18.8 to 112.2 ± 25.2 ml*beatpeak−1 and by 13.3% from 91.5 ± 24.8 to 105.5 ± 24.8 ml*beat 1(p< 0.05). Blood and plasma volume were unchanged from before to after training in the OTG. CONCLUSIONS: Breathing 100% oxygenated air during aerobic interval training does not improve exercise capacity to a greater extent than during ambient air training in stable CAD patients.