Additive effect of free walking exercise on liver enzymes, fatigue severity, triglycerides, and sleeping quality in obstructive sleep apnea patients with non-alcoholic fatty liver: randomized controlled trial

Introduction
Besides dyslipidemia, insulin resistance, and/or glucose intolerance, nonalcoholic fatty liver disease (NAFLD) - an excessive accumulation of fats/lipoproteins (mainly triglycerides) in the hepatic tissues - is one of common obstructive sleep apneainduced metabolic complications. Studies assessing the efficacy of the first-line therapy, continuous positive airway pressure (CPAP) in patients with obstructive sleep apnea (OSA) and NAFLD report conflicting findings. This study aimed to investigate the efficacy of free walking exercise in OSA patients with NAFLD.

Material and methods
Forty moderate-to-severe OSA patients with NAFLD were randomly assigned to a CPAP group (n = 20) or a group of CPAP plus free walking program (aerobic exercise group, n = 20). The forty patients used the 4-hour night CPAP daily. In the group that received CPAP plus a free daily walking program. Pittsburgh Sleep Quality Index, serum alanine and aspartate transaminases, body mass index (BMI), fatigue severity scale, serum triglycerides, and Epworth sleepiness scale were assessed before and after 12 weeks.

Results
Except for the BMI of the group of CPAP only, within-group analysis showed a statistical improvement in OSA patients' outcomes in both groups [p < 0.001 for all outcomes of both groups, except p-value of serum triglycerides (p = 0.025)], still, these improvements were high in the group of CPAP and free walking. Statistically improved outcomes (p < 0.05) were reported for the group of CPAP and free walking after comparing post-values of outcomes between groups.

Conclusions
Adding free walking to CPAP maximize therapeutic gains of CPAP in OSA patients with NAFLD.