Right ventricular metabolic adaptations to high-intensity interval and moderate-intensity continuous training in healthy middle-aged men

: Marja A. Heiskanen, Tuija Leskinen, Ilkka H. A. Heinonen, Eliisa Löyttyniemi, Jari-Joonas Eskelinen, Kirsi Virtanen, Jarna C. Hannukainen, Kari K. Kalliokoski

: 2016

: American journal of physiology : heart and circulatory physiology

: American journal of physiology. Heart and circulatory physiology

: Am J Physiol Heart Circ Physiol

: 311

: 3

: H667

: H675

: 9

: 1522-1539

DOI: https://doi.org/10.1152/ajpheart.00399.2016(external)

BACKGROUND
Despite the recent studies on structural and functional adaptations of the right ventricle (RV) to exercise training, adaptations of its metabolism remain unknown. We investigated the effects of short-term high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on RV glucose and fat metabolism.
METHODS
Twenty-eight untrained, healthy 40-55 years old men were randomized into HIIT (n = 14) and MICT (n = 14) groups. Subjects performed six supervised cycle ergometer training sessions within two weeks (HIIT session: 4-6 x 30 s all-out cycling / 4min recovery, MICT session: 40-60 min at 60% VO2peak). Primary outcomes were insulin-stimulated RV glucose uptake (RVGU) and fasted state RV free fatty acid uptake (RVFFAU) measured by positron emission tomography. Secondary outcomes were changes in RV structure and function determined by cardiac magnetic resonance.
RESULTS
RVGU decreased after training (-22% HIIT, -12% MICT, p=0.002 for training effect) but RVFFAU was not affected by the training (p=0.74). RV end-diastolic and end-systolic volumes increased +5% and +7% for HIIT and +4% and +8% for MICT (p=0.002 and 0.005 for training effects, respectively), but ejection fraction mildly decreased (-2% HIIT, -4% MICT, p=0.034 for training effect). RV mass and stroke volume remained unaltered. None of the observed changes differed between the training groups (p > 0.12 for group*training interaction).
CONCLUSIONS
Only two weeks of physical training in previously sedentary subjects induces changes in RV glucose metabolism, volumes, and ejection fraction, which precede exercise-induced hypertrophy of RV.