Muscle maintenance by volitional contraction against applied electrical stimulation

Changes in diffusion tensor imaging (DTI) eigenvalues of skeletal muscle due to hybrid exercise training

Several studies have proposed the cell membrane as the main water diffusion restricting factor in the skeletal muscle cell. We sought to establish whether a particular form of exercise training (which is likely to affect only intracellular components) could affect water diffusion. The purpose of this study is to characterise prospectively the changes in diffusion tensor imaging (DTI) eigenvalues of thigh muscle resulting from hybrid training (HYBT) in patients with non-alcoholic fatty liver disease (NAFLD). Twenty-one NAFLD patients underwent HYBT for 30 minutes per day, twice a week for 6 months. Patients were scanned using DTI of the thigh pre- and post-HYBT. Fractional anisotropy (FA), apparent diffusion coefficient (ADC), the three eigenvalues lambda 1 (λ1), λ2, λ3, and the maximal cross sectional area (CSA) were measured in bilateral thigh muscles: knee flexors (biceps femoris (BF), semitendinosus (ST), semimembranous (SM)) and knee extensors (medial vastus (MV), intermediate vastus (IV), lateral vastus (LV), and rectus femoris (RF)), and compared pre- and post-HYBT by paired t-test. Muscle strength of extensors (P<0.01), but not flexors, increased significantly post-HYBT. For FA, ADC and eigenvalues, the overall picture was of increase. Some (P<0.05 in λ2 and P<0.01 in λ1) eigenvalues of flexors and all (λ1-λ3) eigenvalues of extensors increased significantly (P<0.01) post-HYBT. HYBT increased all 3 eigenvalues. We suggest this might be caused by enlargement of muscle intracellular space.

Hybrid training of voluntary and electrical muscle contractions reduces steatosis, insulin resistance, and IL-6 levels in patients with NAFLD: a pilot study

BACKGROUND

Physical inactivity is a risk factor for the development of non-alcoholic fatty liver disease (NAFLD). "Hybrid training", a training that involves both voluntary and electrical muscle contractions, causes beneficial alterations in muscles even after short durations of exercise. The aim of this study was to investigate the therapeutic efficacy of hybrid training in patients with NAFLD.

METHODS

Thirty-five patients with NAFLD who were resistant to lifestyle counseling were assigned to a hybrid-training group (n = 12) or a control group (n = 23). In the hybrid-training group, quadriceps and hamstrings were contracted voluntarily or electrically for 19 min twice a week. In the control group, patients received lifestyle counseling. The therapeutic efficacy of the hybrid training was evaluated after 12 weeks of the intervention.

RESULTS

Serum alanine aminotransferase (ALT) levels and hepatic steatosis grade were significantly decreased in the hybrid-training group compared to that of the control group (-14.1 ± 5.8 vs. 3.5 ± 5.4 IU/mL; P < 0.05, -0.67 ± 0.19 vs. 0.09 ± 0.06 grade; P < 0.01, respectively). No significant changes were seen between the two groups in skeletal muscle mass. The decreases in homeostasis model assessment of insulin resistance (HOMA-IR) value and in serum IL-6 levels were significantly greater in the hybrid-training group than in the control group (-6.2 ± 3.2 vs. 0.4 ± 0.6; P < 0.05, -3.1 ± 1.1 vs. 1.1 ± 0.5 pg/mL; P < 0.01, respectively).

CONCLUSION

Hybrid training of voluntary and electrical muscle contractions improved hepatic steatosis and reduced insulin resistance and serum IL-6 levels in NAFLD patients who are resistant to lifestyle counseling.