I just found this study made on rats only unfortunattely not humans. But since some people in this forums report that exercise benefits on relieving ssri widhdrawal symptoms. Upon looking to this study, i found that exercise could contribute to homeostasis of the brain. It seems to help upregulate the serotonin autoreceptors wish are downregulated on SSR chronic use.
Exercise, Energy Intake, Glucose Homeostasis, and the Brain
Additionally, wheel running facilitates the recovery of stress-evoked disruptions in diurnal rhythms of physiology and sleep architecture (Fleshner et al., 2013; R.S. Thompsonand M.F., unpublished observations), improves corticosterone response habituation (Sasse et al., 2008), and elicits plasticity in serotonergic, noradrenergic, and dopaminergic stress-responsive brain circuitry
Regular, moderate physical activity (6 weeks wheel running) produces adaptations in the circuit that include upregulation of 5HT1A inhibitory autoreceptors on DRN cell bodies and a downregulation in 5HT2C receptors in DRN projection sites, amygdala (AMG) and dorsal striatum (DS). Together, these changes constrain the 5HT response to uncontrollable stress and prevent neural sensitization and the expression of learned helplessness behaviors.