Mitochondrial quality control and apoptosis have been described as key components in the pathogenesis of
nonalcoholic steatohepatitis (NASH); exercise is recognized as a nonpharmacological strategy to counteract NASH-associated consequences. We aimed to analyze the effect of voluntary physical activity (VPA) and
endurance training (ET) against NASH-induced
mitochondrial permeability transition pore (mPTP) opening and mitochondrial and cellular quality control deleterious alterations. Forty-eight male Sprague-Dawley rats were divided into standard-diet sedentary (SS, n = 16), standard-diet VPA (n = 8), high-fat diet sedentary (HS, n = 16), and high-fat diet VPA (n = 8). After 9 weeks of diet treatment, half of the SS and HS groups were engaged in an ET program for 8 weeks, 5 days/week, 1 h/day. Liver
mPTP susceptibility through osmotic swelling,
mPTP-related
proteins (
cyclophilin D, Sirtuin3,
Cofilin-1), markers of mitochondrial biogenesis ((
mitochondrial transcription factor A (Tfam) and
peroxisome proliferator-activated receptor gamma co-activator
protein (PGC-1α)), dynamics (Mitofusin 1 (Mfn1), Mitofusin 2 (Mfn2),
Dynamin related
protein 1, and
Optic atrophy 1)), auto/mitophagy (
Beclin-1,
microtubule-associated protein 1 light chain 3, p62, PINK1, and Parkin), and apoptotic signaling (Bax, Bcl-2) and
caspases-like activities were assessed. HS animals showed an increased susceptibility to
mPTP, compromised expression of Tfam, Mfn1, PINK1, and Parkin and an increase in Bax content (HS vs. SS). ET and VPA improved biogenesis-related
proteins (PGC-1α) and autophagy signaling (
Beclin-1 and
Beclin-1/Bcl-2 ratio) and decreased apoptotic signaling (
caspases 8 activity, Bax content, and Bax/Bcl-2 ratio). However, only ET decreased
mPTP susceptibility and positively modulated Bcl-2, Tfam, Mfn1, Mfn2, PINK1, and Parkin content. In conclusion, exercise reduces the increased susceptibility to
mPTP induced by NASH and promotes the increase of auto/mitophagy and mitochondrial fusion towards a protective phenotype.