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 (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.

Safety and Feasibility of Neuromuscular Electrical Stimulation in Patients with Extracorporeal Membrane Oxygenation.

Background/Objectives: The aim of this study was to investigate the feasibility and safety of neuromuscular electrical stimulation (NMES) in patients on extracorporeal membrane oxygenation (ECMO) and thoroughly assess any potential adverse events. Methods: We conducted a prospective observational study assessing safety and feasibility, including 16 ICU patients on ECMO support who were admitted to the cardiac surgery ICU from January 2022 to December 2023. The majority of patients were females (63%) on veno-arterial (VA)-ECMO (81%), while the main cause was cardiogenic shock (81%) compared to respiratory failure. Patients underwent a 45 min NMES session while on ECMO support that included a warm-up phase of 5 min, a main phase of 35 min, and a recovery phase of 5 min. NMES was implemented on vastus lateralis, vastus medialis, gastrocnemius, and peroneus longus muscles of both lower extremities. Two stimulators delivered biphasic, symmetric impulses of 75 Hz, with a 400 µsec pulse duration, 5 sec on (1.6 sec ramp up and 0.8 sec ramp down) and 21 sec off. The intensity levels aimed to cause visible contractions and be well tolerated. Primary outcomes of this study were feasibility and safety, evaluated by whether NMES sessions were successfully achieved, and by any adverse events and complications. Secondary outcomes included indices of rhabdomyolysis from biochemical blood tests 24 h after the application of NMES. Results: All patients successfully completed their NMES session, with no adverse events or complications. The majority of patients achieved type 4 and 5 qualities of muscle contraction. Conclusions: NMES is a safe and feasible exercise methodology for patients supported with ECMO.