Case Report: Metabolic adaptations to intensive aerobic training in Parkinson's disease: autonomic and...

Aerobic exercise is a key non-pharmacological intervention in Parkinson's disease (PD), yet the physiological mechanisms underlying its therapeutic effects remain incompletely understood. This case report aimed to investigate metabolic and cardiovascular adaptations to an intensive aerobic training programme in a person with PD, with particular focus on metabolic efficiency and insulin-like growth factor 1 (IGF-1) response.

A 72-year-old man with idiopathic PD (Hoehn & Yahr stage II, ON medication) participated in a 4-week intensive treadmill training programme (20 sessions) within the METEX-PD protocol. Exercise was performed at a constant external workload (5.0-5.5 km·h⁻¹; 6.0-8.8 METs). Heart rate (HR) was continuously monitored, oxygen uptake ( $\dot{V}$ O₂) was assessed using a portable metabolic analyser, post-exercise blood lactate concentration was measured, and serum IGF-1 levels were evaluated. Assessments were conducted at baseline, mid-intervention, and post-training.

Progressive reductions in HR, $\dot{V}$ O₂, measured METs, and energy cost were observed throughout the intervention, indicating improved aerobic efficiency despite the maintenance of a constant external workload. HR responses across training sessions showed a peculiar pattern suggestive of chronotropic incompetence and cardiovascular drift. Non metabolic Hyperventilation occurred during post training testing. Serum IGF-1 levels increased following the training period, whereas no acute exercise-induced changes were detected. Blood lactate responses remained consistent with the prescribed exercise intensity.

Intensive aerobic training induced favourable metabolic adaptations in this individual with PD, as evidenced by improved aerobic efficiency and increased circulating IGF-1 levels. These adaptations occurred despite potential autonomic dysfunction affecting cardiovascular responses. The findings support the use of direct metabolic measurements to better characterise training adaptations and optimise individualised aerobic exercise prescription in people with PD. Further studies are warranted to confirm these observations in larger cohorts.