Effects of High-Intensity Interval Exercise Training on Skeletal Myopathy of Chronic Heart Failure

Background: It remains controversial which type of exercise elicits optimum adaptations on skeletal myopathy of heart failure (HF). Our aim was to evaluate the effect of high-intensity interval training (HUT), with or without the addition of strength training, on skeletal muscle of HF patients. Methods and Results: Thirteen male HF patients (age 51 +/- 13 years, body mass index 27 +/- 4 kg/m(2)) participated in either an HIIT (AER) or an HILT combined with strength training (COM) 3-month program. Biopsy samples were obtained from the vastus lateralis. Analyses were performed on muscle fiber type, cross-section area (CSA), capillary density, and mRNA expression of insulin-like growth factor (IGF) 1 isoforms (ie, IGF-lEa, IGF-lEb, IGF-lEc), type-1 receptor (IGF-1R), and binding protein 3 (IGFBP-3). Increased expression of IGF-lEa, IGF-lEb, IGF-lEc, and IGFBP-3 transcripts was found (1.7 +/- 0.8, 1.5 +/- 0.8, 2.0 +/- 1.32.4 +/- 1.4 fold changes, respectively; P <.05). Type I fibers increased by 21% (42 +/- 10% to 51 +/- 7%; P <.001) and capillary/fiber ratio increased by 24% (1.27 +/- 0.22 to 1.57 +/- 0.41; P =.005) in both groups as a whole. Fibers' mean CSA increased by 10% in total, but the increase in type I fibers' CSA was greater after AER than COM (15% vs 6%; P <.05). The increased CSA correlated with the increased expression of IGF-lEa and IGF-lEb. Conclusions: HTIT reverses skeletal myopathy of HF patients, with the adaptive responses of the IGF-1 bioregulation system possibly contributing to these effects. AER program seemed to be superior to COM to induce muscle hypertrophy.