Impact of endurance exercise on levodopa-associated cortisol release and force increase in patients with Parkinson's disease.

Levodopa (LD) application improves motor symptoms and reduces cortisol levels in patients with Parkinson's disease (PD). Endurance exercise enhances cortisol release in proportion to the intensity of the effort and thus may counteract the LD associated cortisol decrease. We measured levels of cortisol and LD over an 1-h long interval following administration of soluble 200 mg LD/50 mg benserazide with concomitant maximal grip strength assessment in 16 PD patients under cued conditions during rest and endurance exercise. The motor response, the plasma levels of cortisol and LD did not significantly differ between both conditions. Cortisol concentrations significantly decreased even during exercise. Grip strength only significantly went up during rest. Endurance exercise did not counteract the LD associated decreased cortisol release. Since cortisol improves muscle function, the lack of increase in maximal grip strength following LD administration during exercise may contribute to reduced exercise capacity, which is reported by PD patients.