Walking and Jogging: Quantification of Muscle Activity of the Lower Extremities

Abstract

Basmajian (1967) defined locomotion as “the translation of the centre of gravity through space along a path requiring the least expenditure of energy”. Taking as reference the centre of gravity (CG) of the body, it has been already established that the trajectory while walking or jogging follows a sinusoidal course (Inman 1968), with two vertical summits per stride (one cycle of locomotion). During locomotion, the movement of translation of the body is produced by the spatial angular movement of the lower extremities that shows support and non-support phases. The basic unit of measurement in gait analysis is the gait cycle (GC) or stride. The gait cycle is commonly divided into two phases: 1) stance phase, and 2) non-support phase. In walking, in the stance phase there are two periods of double support. In jogging cycle (JC) the phase of non support is composed of two float periods (when both feet are airborne) and between both periods there is one period of swing of the ipsilateral leg. Walking and jogging present differences at: 1) the velocity pattern, which is higher in jogging, as it implies joint movements of higher amplitude and speed; 2) the duration of cycles and of their respective phases; 3) the kinematics of: a) the peaks of the body CG trajectory (its amplitude and time of appearance), and b) of the joints, as there are wider angular joints displacements and different distribution of arches movements during cycle phases (Novacheck, 1998); 4) the kinetic: a) amplitude, duration, and evolution of the ground reaction force (Mann, 1982), external moments of force, and muscle power (Winter, 1983a and 1983b); b) misalignment of CG between the segments of the leg and of the upper part of the body (head, trunk, and arms); c) inertia; and 5) the mechanisms for saving energy structures (Cavagna & Kaneko, 1977; van Ingen Schenau et al., 1987). Several studies have compared the muscle activity of the legs during walking and jogging or running. In the works of Mann & Hagy (1980), and Mann (1982), the subjects were trained athletes, and in the work of Ounpuu (1994) they were children. In all the above-mentioned papers the muscle activity was recorded from only one leg, and the muscular activity was qualitatively described rather than quantified. Nilsson et al. (1985) and Gazendam and Hof (2007) quantified the profiles of averaged rectified EMGs at different speeds of locomotion and mode of progression in humans on motor-driven treadmill.