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Characteristics of walking techniques with different pelvic height and pelvic rotation: effect on muscle activation and energy consumption

100%

Kapeleti M. , Ubović M. , Ilić D. , Mrdaković V.

Acta of Bioengineering and Biomechanics

2024

tom Vol. 26, no. 1

165--179

Previous studies have proven that modifications in the natural walking technique alter muscle activation and energy consumption. This research aimed to determine the differences in muscle activation, energy consumption, kinematic characteristics, perceived muscular exertion and perceived cardio-respiratory fatigue between natural and modified walking techniques with altered pelvic height and rotation. Methods: Nine physically active, non-injured males walked on a treadmill. Modified walking techniques assumed maintenance of constant pelvic height and application of maximal pelvic rotation. Walking speed was subtransit – 0.4 km/h less than the transit. Sampled variables were: average normalized maximal activation during contact and swing phase relativized to maximal voluntary activation, average submaximal oxygen consumption relativized to body mass and subtransit speed, average step length and frequency, rating of perceived muscular exertion and perceived cardio-respiratory fatigue. Muscle activation, energy consumption and kinematic characteristics were assessed throughout each walking session. Perceived muscular exertion and perceived cardio-respiratory fatigue were evaluated post-session. Electromyographic activity was assessed for rectus femoris, gluteus maximus, vastus medialis, biceps femoris, tibialis anterior and gastrocnemius lateralis. Results: The most significant changes in muscle activation were observed during the contact phase. A decrease in pelvic height increased muscle activation of rectus femoris, vastus medialis and gastrocnemius lateralis. An increase in pelvic rotation increased muscle activation of all monitored muscles except for gluteus maximus. Both modifications increased energy consumption, perceived muscular exertion and perceived cardio-respiratory fatigue, and altered kinematic characteristics. Conclusions: Modifications in pelvic height and rotation at the same walking speed alter muscle activation, energy consumption, kinematic characteristics, perceived exertion and fatigue.

Studying of movement kinematics of dynamically active sieve

63%

Popolov D. , Shved S. , Zaselskiy I. , Pelykh I.

Mechanics and Mechanical Engineering

2019

tom Vol. 23, nr 1

94--97

The article presents the movement kinematics of the modular bar element of a dynamically active polymer sieve of a vibrating screen. On the basis of analytical methods, the mathematical model was obtained, which makes it possible to determine the law and trajectory of the modular bar element movement depending on its geometric characteristics, physico-mechanical properties of the polymer material, the regime and technological parameters of the vibrating screen. The results of this research show that in the working frequency range of the vibrating screen grate, modular bar element of the dynamically active sieve moves along the trajectories, the envelope of which is represented by Cassini’s ovals, which along with the generation of the amplitude component in the horizontal and vertical directions allows one to obtain the selfcleaning effect of the sowing surface.