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 (HIIT), 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/m2) participated in either an HIIT (AER) or an HIIT 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-1Ea, IGF-1Eb, IGF-1Ec), type-1 receptor (IGF-1R), and binding protein 3 (IGFBP-3). Increased expression of IGF-1Ea, IGF-1Eb, IGF-1Ec, 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-1Ea and IGF-1Εb.
Conclusions: HIIT 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.
Keywords: Heart failure; insulin-like growth factor; interval training; skeletal muscle.
Copyright © 2016 Elsevier Inc. All rights reserved.