Among these neuroendocrine markers, cortisol, insulin, and klotho may serve as robust biomarkers for assessing exercise benefits in PD because: 1) they exhibit consistent abnormalities in PD; 2) they play key roles in PD-related pathophysiological pathways; and 3) they have been shown to respond significantly to exercise (Fig. 4). Here, INS is linked to Parkinson disease.