Hemodynamic effects of high intensity interval training in COPD patients exhibiting exercise-induced dynamic hyperinflation

• Interval exercise training improves cardiac output at peak levels of exercise in COPD.
• Interval exercise training reduces the magnitude of dynamic hyperinflation in COPD.
• Mitigation of dynamic hyperinflation improves central hemodynamic responses to a given power output in hyperinflated COPD.
• Rehabilitative exercise training induces a more efficient hemodynamic response to a given power output in patients with COPD.
• Non-invasive measurement of cardiac output in patients with COPD may improve the evaluation of the efficacy of pharmacological and non-pharmacological interventions.

Dynamic hyperinflation (DH) has a significant adverse effect on cardiovascular function during exercise in COPD patients. COPD patients with (n = 25) and without (n = 11) exercise-induced DH undertook an incremental (IET) and a constant-load exercise test (CLET) sustained at 75% peak work (WRpeak) prior to and following an interval cycling exercise training regime (set at 100% WRpeak with 30-s work/30-s rest intervals) lasting for 12 weeks. Cardiac output (Q) was assessed by cardio-bio-impedance (PhysioFlow, enduro, PF-O7) to determine Q mean response time (QMRT) at onset (QMRTON) and offset (QMRTOFF) of CLET. Post-rehabilitation only those patients exhibiting exercise-induced DH demonstrated significant reductions in QMRTON (from 82.2 ± 4.3 to 61.7 ± 4.2 s) and QMRTOFF (from 80.5 ± 3.8 to 57.2 ± 4.9 s). These post-rehabilitation adaptations were associated with improvements in inspiratory capacity, thereby suggesting that mitigation of the degree of exercise-induced DH improves central hemodynamic responses in COPD patients.