Treadmill training improves overground walking economy in Parkinson's disease: a randomized, controlled pilot study.

Gait disturbances are one of the principal and most incapacitating symptoms of Parkinson's disease (PD). In addition, walking economy is impaired in PD patients and could contribute to excess fatigue in this population. An important number of studies have shown that treadmill training can improve kinematic parameters in PD patients. However, the effects of treadmill and overground walking on the walking economy remain unknown. The goal of this study was to explore the walking economy changes in response to a treadmill and an overground training program, as well as the differences in the walking economy during treadmill and overground walking. Twenty-two mild PD patients were randomly assigned to a treadmill or overground training group. The training program consisted of 5 weeks (3 sessions/week). We evaluated the energy expenditure of overground walking, before and after each of the training programs. The energy expenditure of treadmill walking (before the program) was also evaluated. The treadmill, but not the overground training program, lead to an improvement in the walking economy (the rate of oxygen consumed per distance during overground walking at a preferred speed) in PD patients. In addition, walking on a treadmill required more energy expenditure compared with overground walking at the same speed. This study provides evidence that in mild PD patients, treadmill training is more beneficial compared with that of walking overground, leading to a greater improvement in the walking economy. This finding is of clinical importance for the therapeutic administration of exercise in PD.

Ventral premotor to primary motor cortical interactions during noxious and naturalistic action observation.

Within the motor system, cortical areas such as the primary motor cortex (M1) and the ventral premotor cortex (PMv), are thought to be activated during the observation of actions performed by others. However, it is not known how the connections between these areas become active during action observation or whether these connections are modulated by the volitional component induced by the action observed. In this study, using a paired pulse transcranial magnetic stimulation (ppTMS) method, we evaluated the excitability of PMv-M1 connections during the observation of videos showing a human hand reaching to grasp a ball (naturalistic grasping video) or a switched on soldering iron (noxious grasping video). The results show that the observation of the naturalistic grasping action increased the M1 excitability and changed the strength of the PMv-M1 connections. The observation of the noxious grasping action did not induce any change in the excitability of the PMv-M1 connections throughout the video, but the strength of PMv-M1 connectivity was reduced. These results demonstrate that the PMv-M1 connections are modulated differently depending on whether the action observed would or would not be performed in real life.