FNDC5 and Alzheimer disease: This study investigated the effects of 8 weeks of pretreatment with coenzyme Q10 (CoQ10) and high‐intensity interval training (HIIT) alone and in combination on FNDC5, irisin, BDNF, and amyloid‐beta (Aβ) plaque formation in the hippocampus of Aβ‐related AD rats.