# A Novel Wearable Foot and Ankle Monitoring System for the Assessment of Gait Biomechanics
###### Abstract
The tibialis anterior activity during the gait cycle is described as follows: eccentric contraction during heel strike; it continues to contract eccentrically during loading response (initial double limb support) to control plantar flexion moment; inactive during the remainder of the stance phase; and concentric contraction during the swing phase. The gastrocnemius muscle is active in most of the stance phase, initially in eccentric contraction and afterwards in concentric contraction. It acts mostly towards stabilizing the knee joint and controlling the fall of the center of mass during the single support phase of the gait [10; 17]. The research of [PERSON] et al., among others, studied the tibialis anterior during gait, investigating the muscular activity during the stance phase [18]. [PERSON] et al. [19] and [PERSON] et al. [20], among others, have studied the Gastrocnemius during gait. The movement of one segment implies the balanced action of the agonist-antagonist muscles, e.g., flexors-extensors, abductor-adductors, internal-external rotators. Due to faulty posture and movements, as well as diseases, when the function of a muscular coupled with action on a specific joint is altered or unbalanced, one must take into account that there will be disfunctions in other joints of the kinetic chain as well. As far as gait is concerned, this implies all joints of the lower kinetic chain of the body, namely ankle, knee, hip and spine, and their muscles, namely calf muscles, pretibial muscles for the ankles, quadriceps, hamstring muscles for the knee, iliopsoas and gluteus maximus for the hip [10]. Our work is motivated by the fact that a series of body conditions can be inferred from foot biomechanics. For exemplification, the impact of foot position and foot posture on the body balance is assessed by [PERSON] et al. in [21] and [PERSON] et al. in [22], indicating correlations with defective body posture. When considering normal posture, one looks for the proper alignment of the head and shoulders, the normal curves of the spine, the neutral posture of the pelvis, hips and knees and the 90 deg angle of the ankle joints which are the first weight bearing joints implied in locomotion [2]. Additionally, numerous studies use foot posture as an indicator of the state of health. For exemplification, [PERSON] et al. correlates foot posture index and core stability with the body mass index in the adult segment [23]. A similar study is presented by [PERSON] et al. for the elderly segment [24]. Further correlation of foot posture to age and joint flexibility for children is discussed in [25]. Postural conditions further enable the analysis of locomotor dynamics, in terms of core stability, balance and sway [22; 26; 27]. Locomotion is the movement of the body by a coordinated series of muscle activities, in a particular direction, while the relation of the body as a whole to the ground is maintained. As such, based on the kinetic link principle, the human body can be regarded in terms of a series of interrelated links or segments. Movement of one segment affects both the proximal and the distal segments respectively [28]. As such, further considerations which motivate our work regard the integration of foot biomechanics and foot kinematics assessment into the analysis of locomotor patterns [29]. For the assessment of foot kinematics, the scientific literature proposes several models, the most employed being the three-segments Oxford foot model [30; 31; 32], the Rizzoli foot \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Gait Phase** & **Acceleration** & **Midswing** & **Deceleration** \\ \hline
**Duration—\% of Total** & **0–2\%** & **0–10\%** & **10–30\%** \\ \hline  & & & \\  & & & \\ \hline  & & & \\ \end{tabular}
\end{table} 
Table 2: Muscular activity throughout the swing phases of the gait cycle [10]. model [32; 33], and the Heidelberg measurement method [32; 34].