Academic journal article Journal of Physical Education and Sport

Detection of Bilateral Asymmetries in the Lower Extremities under Various Loading Conditions in Healthy Subjects: An Experimental Study

Academic journal article Journal of Physical Education and Sport

Detection of Bilateral Asymmetries in the Lower Extremities under Various Loading Conditions in Healthy Subjects: An Experimental Study

Article excerpt

(ProQuest: ... denotes formulae omitted.)

Introduction

The human body presents a specific characteristic when it performs various movements. The scientific term for this phenomenon was first introduced as "laterality" and according to Schenk (1980) it is "the functional dominance of one limb or one side of the human body over the opposite limb or side" (In: Salonikidis K., 2002). Laterality lies on the fact that the two sides of the human body differ principally. Each side is controlled by the contra-lateral brain hemisphere. Although the origin of this phenomenon is yet to be found, its functional effects regarding many movement tasks, like writing and kicking, have been documented (Gabbard C. and Hart S., 1996).

In the case of lower limbs, the lack of fundamental knowledge regarding their lateralisation leads to a behavioral approach in order to document and generalise their roles and differentiation. Sadeghi H. et al. (1997), based on observation, pointed out in their study that one lower limb has mainly power absorption behavior while the other has mainly power generation behavior. In earlier studies these functions have been appointed to the left and right leg respectively, as were observed in large sample groups (Matsusaka N. et al, 1985, Hirokawa S., 1989). These studies support the fact that the dominant leg is responsible for the propulsion during the displacement of the human body while the non-dominant leg is responsible for supporting the bodyweight and maintaining balance.

Like other movements, gait has stabilising and mobilising features. However, unlike other motor skills like kicking a ball or jumping, gait requires a more symmetrical sequence of movements of the two sides, due to the continuity of its coordination. In normal gait, the movements of the two legs seem identical and several studies present findings that corroborate this. The vertical and horizontal ground reaction forces, joint angle time histories, EMG patterns of lower limb muscles and energy consumption were found to be symmetrical in relative studies (Claeys R., 1983, Hamill et al, 1984, Hannah R.E. et al. 1984, Chou L.S. et al. 1995, Hesse S. et al. 1997, Wall, J.C. and Turnbull, G.I 1986, Pierotti, S.E et al., 1991, Arsenault A.B., 1986).

On the contrary, there are several studies which indicate gait asymmetries. Many of them have measured the same variables with the ones that reported symmetry and came to different conclusions (Arsenault A.B. 1986, Ounpuu S. and Winter D.A, 1989). Law H.T. (1987) found asymmetry in the velocities, stride lengths and stride times between the two lower limbs. Also, Seeley M.K. et al. (2008) investigated the vertical and anteroposterior GRFs and found that the propulsive impulse of the dominant limb is 7% larger than the non-dominant limb in fast speed gait, a fact which partially verifies the observations of Matsusaka N. et al. (1985).

The Center of Mass (CoM) as a major determinant of gait is being reasoned in the early study of Saunders J.B. et al. (1953), where its movement is considered to be the resultant action of all the ground reaction forces applied upon the human body and thus, it is feasible to observe the patterns developed throughout any activity by just measuring the change of every variable relatively to the CoM: "ideally, the CoM can be regarded as the summation of all forces acting upon the body" (Saunders J.B. et al. 1953).

The study of the motion of the CoM was used for the analysis of asymmetric gait. One study which is particularly related to the current project reported asymmetries in the lateral, vertical and anterior posterior oscillations of the CoM within the gait cycle (Crowe A. et al., 1995).

Objectives

The aim of the project was to investigate the gait of young healthy adults under the effect of large evenly distributed loads and test the assumption of existing asymmetries between the two lower limbs during the activity, under the effect of large evenly distributed loads. …

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