Mechanical Energy Recovery during Walking in Patients with Parkinson Disease

<div><p>The mechanisms of mechanical energy recovery during gait have been thoroughly investigated in healthy subjects, but never described in patients with Parkinson disease (PD). The aim of this study was to investigate whether such mechanisms are preserved in PD patients despite an altered pattern of locomotion. We consecutively enrolled 23 PD patients (mean age 64±9 years) with bilateral symptoms (H&Y ≥II) if able to walk unassisted in medication-off condition (overnight suspension of all dopaminergic drugs). Ten healthy subjects (mean age 62±3 years) walked both at their ‘preferred’ and ‘slow’ speeds, to match the whole range of PD velocities. Kinematic data were recorded by means of an optoelectronic motion analyzer. For each stride we computed spatio-temporal parameters, time-course and range of motion (ROM) of hip, knee and ankle joint angles. We also measured kinetic (W_k), potential (W_p), total (W_totCM) energy variations and the energy recovery index (ER). Along with PD progression, we found a significant correlation of W_totCM and W_p with knee ROM and in particular with knee extension in terminal stance phase. W_k and ER were instead mainly related to gait velocity. In PD subjects, the reduction of knee ROM significantly diminished both W_p and W_totCM. Rehabilitation treatments should possibly integrate passive and active mobilization of knee to prevent a reduction of gait-related energetic components.</p></div

Energy components.

<p>Left column: PD_M and HC_N. Right column: PD_S and HC_S. Black lines refer to one representative PD and grey lines to one HC. Thick and thin lines refer to the average time courses ±SD of different trials, respectively.</p

Energetic, spatio-temporal and kinematic parameters.

<p>Energetic, spatio-temporal and kinematic parameters.</p

Time courses of knee flexion/extension angles.

<p>(A) Comparison between one representative PD_M (black lines) and one HC_N (grey lines). (B) Comparison between one representative PD_S (black lines) and one HC_S (grey lines). Thick and thin lines refer to the average time courses ±SD of different trials, respectively. The intervals of maximum knee extension, reached during the stance phase, are highlighted in grey.</p

EMG recordings (RMS).

<p>Imb. = Imbalance; Unl. = Unloading; SOL = Soleus muscle; TA = Tibialis anterior muscle; p values refers to Wilcoxon-Mann-Whitney U Test.</p

Kinematic measurements.

<p>AP = Antero-posterior; ML = Medio-materal. Imb. = Imbalance; Unl. = Unloading; FL = foot length; BH = body height; SWto = Heel-off of the swing foot. p values refers to Wilcoxon-Mann-Whitney U Test.</p

Demographic and clinical characteristics.

<p>Demographic and clinical characteristics.</p

Recorded data at gait initiation.

<p>Centre of pressure (CoP, black line) and centre of mass (CoM, dashed line) displacement in a healthy subject (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092736#pone-0092736-g001" target="_blank">figure 1</a> left) and child with RTT (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092736#pone-0092736-g002" target="_blank">figure 2</a> left) with corresponding EMG activity of tibialis anterior (TA) and soleus muscles (SOL) of swing and stance foot (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092736#pone-0092736-g001" target="_blank">figure 1</a> right and 2 right). The dotted line (in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092736#pone-0092736-g001" target="_blank">figure 1</a> left and 2 left) shows CoP-CoM distance at toe-off of the swing foot (SWto). In <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092736#pone-0092736-g001" target="_blank">figure 1</a> (right), arrows indicate bilateral suppression of the tonic activity of SOL which, together with the subsequent activation of TA, is responsible for the backward displacement of the CoP. This synergistic activity of pairs of postural muscles (i.e. TA and SOL) is not present in RTT girls (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0092736#pone-0092736-g002" target="_blank">figure 2</a> right). <i>Imbalance phase</i>, from the instant APAonset, at which the CoP start moving backward, to the instant of heel-off of the swing foot (SWho). <i>Unloading phase</i>, from SWho to toe-off of the swing foot (SWto). STto is the instant of toe-off of the stance foot.</p

Demographic and clinical data.

<p>Demographic and clinical data.</p