The effects of rigidity on energy expenditure during walking in Parkinson Disease

Parkinson’s disease (PD) is a neurodegenerative disorder associated with the loss of dopamine producing cells, resulting in motor symptoms including rigidity. There is little known on how the mechanical symptoms of PD are related to metabolic efficiency. The purpose of this study was to investigate the effects of rigidity on energy expenditure during walking. We hypothesized that rigidity would positively correlate to metabolic cost of walking. 20 participants were recruited (10 PD; 10 controls). Equipment involved included a metabolic cart to perform indirect calorimetry (TrueOne, ParvoMedics, Sandy, UT), and an isokinetic dynamometer for passive rigidity assessments (HUMAC, CSMi Inc, Boston, MA). PD observed significant differences in rigidity measurements where PD had higher rigidity compared to controls. No significant differences were observed for energy expenditure. A positive moderate correlation between total rigidity work score and absolute VO2 was observed, where greater rigidity relates to greater energy expenditure during walking