# The Relationship between Gait Velocity and Walking Pattern in Hemiplegic Patients
## 1 Introduction  
Stroke is a major public health issue worldwide [1], as it is the second leading cause of death and the third leading cause of disability [2]. The mobility limitations resulting from a stroke, due mostly to hemiparesis, have a significant impact on a patient's independent ambulation [1]. Several studies have shown the effectiveness of rehabilitation in the acute, post-acute and chronic phases of stroke, as it improves walking speed, physical fitness and balance and reduces the risk of falling, fractures and a further decline in mobility [3; 4; 5]. Furthermore, in chronic stroke survivors, an adaptive physical activity (APA) program is also an effective approach to maintain and improve activities of daily living and reduce falls and recourse to rehabilitation services. Additionally, it makes it possible to perform the exercises at home, which increases patient compliance and improves quality of life perception [6]. One of the primary goals in stroke rehabilitation is regaining locomotor ability. Change in gait speed is the most commonly used parameter to evaluate patients because it is easy to measure, cost effective and reliable. Moreover, it is a great functional walking status predictor and an impairment severity index [7]. Spatiotemporal, kinematic and kinetic parameters, widely studied in the existing literature, show a decreased cadence, prolonged swing duration on the paretic side, prolonged stance duration on the non-paretic side and step length asymmetry in post-stroke patients [8]. Previous studies also support that gait asymmetry ratios are more sensitiveoutcome measures [9; 10; 11]. Furthermore, the inadequate propulsion force is correlated to an alteration of the leg extension angle, knee flexion angle and foot dorsiflexion in the paretic side [12]. Strength deficit in the lower limbs appears to be one of the main factors slowing the recovery of walking ability, strictly dependent on abnormal posture and stretching reflexes and loss of voluntary movement resulting from paresis [13]. Hemiparesis leads to impaired motion patterns, abnormal muscle activities and abnormal joint trajectories. Common features are decreased peak hip flexion, peak knee flexion-extension and foot dorsiflexion [14], which generally determine a problem with foot-floor clearance. Compensatory gait strategies to enhance progression and foot-floor clearance, such as circumduction, hip hiking and vaulting, have been described and recognized to increase energy expenditure [14; 15; 16] (Figure 1). All these gait patterns have some common features, but also some significant variations in terms of group muscles weakness and spasticity. In the daily clinical practice, usually hemiplegic or hemiparetic patients adopt one of these gait patterns, but it is not unusual to find their combinations, with a prevalence of some features despite others in the activation sequence of muscles and strategy of progression. Gait modification is part of all three plans for movement of lower limbs. To attain a proper understanding, it is essential to focus on each one. Circumduction gait is an abnormal walking pattern in which a patient, to avoid hitting the ground with the foot in order to achieve its adequate clearance, lifts and moves away from the body the affected lower limb and takes it forward, performing a semi-circular movement. It occurs during the swing phase on the affected side, the compensation consisting in the activation of the leg abduction, and the principal muscles involved are the glutei minimus and medius, assisted by the tensor fasciae latae and adductor muscles. Circumduction is commonly seen in hemiplegic patients but could occur also in severe knee osteoarthritis/arthosis, peripheral nerve injuries with foot drop and hetero-metry of lower limbs. In all these cases, the patient cannot produce a sufficient hip or knee flexion or ankle dorsiflexion.