Benefits of High-Intensity Interval Training in a Young and in an Older De Novo Heart Transplant Recipient- Cases from the HITTS Study

Purpose: High-intensity interval training (HIT) is an effective method to increase exercise capacity in de novo heart transplant recipients, as shown in the recently published HITTS study (High-intensity Interval Training in de novo Heart Transplant recipients in Scandinavia). We were interested to scrutinize the potential effect of HIT in different age categories. The main effects of HIT in one young and one older medically stable de novo heart transplant recipients are reported. Methods: The HITTS study is a randomized controlled study comparing HIT versus moderate intensity continuous training (MICT) in de novo heart transplant recipients (mean 11 weeks after heart transplantation). Eighty-one participants were randomized (1:1) to 9 months of HIT or MICT. The primary endpoint was the change in VO2peak. Secondary endpoints included: Heart rate response, muscle strength and self-reported physical function measured by the Short-Form-36. One of the youngest and one of the oldest participants with the highest changes in VO2peak in the HIT intervention group were selected for this case report. Results: The youngest male (< 25 years old) increased his VO2peak with 15.3 mL/kg/min from baseline to follow-up (from 23.5 to 38.8 mL/kg/min), while the older male (> 55 years old) increased his VO2peak with 12.6 mL/kg/min (from 15.6 to 28.3 mL/kg/min). Muscle strength, heart rate response, O2 pulse and self-reported physical function also increased substantially (Table). The young heart transplant recipient completed 51 exercise sessions whereas the older heart transplant recipient completed 72 sessions. Conclusion: Both the young and the older de novo heart transplant recipient increased their VO2peak with at least 4 METS (> 12 mL/kg/min) after a 9-month long HIT intervention. The results show that both young and older individuals can derive substantial benefit from HIT soon after heart transplantation.