José Andrés Sánchez

Treadmill walking in Parkinson's disease patients: Adaptation and generalization effect

We examined the adaptation and generalization effect of one familiarization treadmill walking session on gait in patients with Parkinsons disease (PD) with different degrees of disease severity. Eight moderate PD patients (Hoehn and Yahr stage 2–2.5), eight advanced PD patients (Hoehn and Yahr 3), and eight matched control subjects participated in this study. Subjects first walked overground on a 10‐m walkway at a self‐selected speed (pretreadmill). They then performed a 20‐min treadmill training session, followed by three trials of overground walking (Post1, Post2, Post3). Cadence, step length, speed, and coefficient of variation of stride time (CV) were recorded. During the treadmill session the advanced PD patients significantly decreased their cadence (t = 3.9, P ≤ 0.01) and increased their step length (t = 4.27, P ≤ 0.01) compared with pretreadmill walking. After the treadmill, all subjects walked overground significantly faster (F = 16.51 P ≤ 0.001) and with a larger step length (F = 13.03 P ≤ 0.01) than pretreadmill walking. The present study shows a specific adaptation to walk over the treadmill for the advanced PD patients. Moreover, this confirms the potential therapeutic use of the treadmill for PD gait rehabilitation since a single familiarization session lead to an increase in the step length and thus to the improvement of the main gait impairment in PD.

The effects of treadmill or overground walking training program on gait in Parkinson's disease

BACKGROUND Gait impairment in Parkinsons disease (PD) patients is characterized by the inability to generate appropriate stride length. Treadmill training has been proposed as a therapeutic tool for PD patients. However, it remains unknown whether treadmill training effects are different from overground walking training. Thus, our goal was to explore the effects of two training programs, walking on a treadmill and walking overground, in PD patients. METHODS 22 PD patients were randomly assigned to a treadmill or overground training group. The training program consisted of 5 weeks (3 sessions/week). Before and after the program we evaluated gait kinematics during walking at preferred and maximal speed; Timed Up and Go (TUG); static posturography and knee extensors strength. Gait parameters were reevaluated in the treadmill training group one month after the cessation of the training. RESULTS Preferred speed walking improved in both groups after the training program. The treadmill training program, but not the overground, led to an improvement in the stride length at the preferred and maximal walking speed in the PD patients. In addition, the treadmill training group showed improvement of the TUG and static posturography tests. The improvement in gait parameters was maintained one month after the cessation of the treadmill training. CONCLUSIONS This study provides evidence of a specific therapeutic effect of treadmill training on Parkinsonian gait and balance. Walking on a treadmill may be used as an easy, effective and accessible way to improve the stride length and balance in PD patients.

How repeatable are the physiological effects of TENS

OBJECTIVE Several studies suggest that transcutaneous electrical stimulation (TENS) can have a variety of effects on the central nervous system (CNS). In this study, we tried to replicate the physiological effects of TENS and to explore its effects on intracortical circuits. METHODS We used transcranial magnetic stimulation (TMS) and spinal reflex testing to examine excitability of intracortical and spinal cord circuits before and after a 30-min period of TENS over the flexor carpi radialis (FCR) muscle. We measured the amplitude of TMS-evoked muscle responses (MEP), short interval intracortical inhibition (SICI), intracortical facilitation (ICF) and cortical antagonist inhibition (CAI) in flexor and extensor carpial radialis (FCR, ECR) muscles as well as spinal reciprocal inhibition (RI) and presynaptic inhibition (PI) from ECR to FCR. RESULTS TENS had no significant effect on any of these measures apart from a reduction in median nerve induced facilitation of FCR when testing CAI. CONCLUSIONS When compared with previous studies, our results suggest that the effects of TENS are highly variable and unreliable, likely by the difficulty in defining precise parameters of stimulation in individual subjects. SIGNIFICANCE Care should be taken in assuming that effects after TENS observed in small populations of subjects will apply equally to a wider population.

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.

Spatiotemporal parameters of gait during treadmill and overground walking in Parkinson's disease

Despite the increasing number of studies that have examined the therapeutic effect of treadmill training programs in Parkinsons disease (PD), there has been little research to evaluate the modifications of gait induced by treadmill walking. We investigated spatiotemporal differences between treadmill and overground walking in patients with PD. PD patients significantly increased their step length and step height; and reduced their cadence, step width and step width variability on the treadmill in comparison with walking overground. PD patients are able to attenuate their short shuffling steps when walking on a treadmill.

The effects of auditory startle and nonstartle stimuli on step initiation in Parkinson's disease†‡§

Auditory external cues enhance step initiation in Parkinsons disease (PD) patients. We wanted to explore whether a startle reaction has a comparable effect on step initiation in PD.

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.

Low-Intensity Cycling Affects the Muscle Activation Pattern of Consequent Countermovement Jumps

Marquez, GJ, Mon, J, Acero, RM, Sanchez, JA, and Fernandez-del-Olmo, M. Low-intensity cycling affects the muscle activation pattern of consequent countermovement jumps. J Strength Cond Res 23(5): 1470-1476, 2009-Players (eg, basketball, soccer, and football) often use a static bicycle during a game to maintain warming. However, the effectiveness of this procedure has not been addressed in the literature. Thus, it remains unknown whether low-intensity cycling movement can affect explosive movement performance. In this study, 10 male subjects performed countermovement jumps before and after a 15-minutes cycling bout at 35% of their maximal power output. Three sessions were tested for 3 different cadences of cycling: freely chosen cadence, 20% lower than freely chosen cadence (FCC−20%), and 20% higher than freely chosen cadence (FCC+20%). Jump height, kinematics, and electromyogram were recorded simultaneously during the countermovement jumps. The results showed a significant decreasing in the height of countermovement jump after cycling at freely chosen cadence and FCC−20% (p = 0.03 and p = 0.04, respectively), but not for FCC+20% cadences. The electromyographic parameters suggest that changes in the countermovement jump after cycling can be attributed to alteration of the pattern of activation and may be modulated by the preceding cycling cadence. Our study indicates that to avoid a possible negative effect of the cycling in the subsequent explosive movements, a cadence 20% higher than the preferred cadence must be used.

The effects of startle and non-startle auditory stimuli on wrist flexion movement in Parkinson's disease

Startle stimuli lead to shorter reaction times in control subjects and Parkinsons disease (PD) patients. However, non-startle stimuli also enhance movement initiation in PD. We wanted to examine whether a startle-triggered movement would retain similar kinematic and EMG-related characteristics compared to one induced by a non-startle external cue in PD patients. In this study we investigated the electromyography pattern and the reaction time during a wrist flexion movement in response to three different stimuli: a visual imperative stimulus; visual stimulus simultaneous with a non-startle auditory stimulus and with a startle auditory stimulus. Ten PD patients and ten aged matched controls participated in this study. The reaction times were faster for startle and non-startle stimuli in comparison with the visual imperative stimulus, in both patients and control subjects. The startle cue induced a faster reaction than the non-startle cue. The electromyography pattern remained unchanged across the conditions. The results suggest that the startle reaction effect for upper limb movements are unimpaired in PD patients and has different characteristics than the effect of non-startle stimuli.