Abstract
Crawling on hands and knees is an early pattern of human infant locomotion, which offers an interesting way of studying quadrupedalism in one of its simplest form. We investigate how crawling human infants compare to other quadruped mammals, especially primates. We present quantitative data on both the gait and kinematics of seven 10-month-old crawling infants. Body movements were measured with an optoelectronic system giving precise data on 3-dimensional limb movements. Crawling on hands and knees is very similar to the locomotion of non-human primates in terms of the quite protracted arm at touch-down, the coordination between the spine movements in the lateral plane and the limbs, the relatively extended limbs during locomotion and the strong correlation between stance duration and speed of locomotion. However, there are important differences compared to primates, such as the choice of a lateral-sequence walking gait, which is similar to most non-primate mammals and the relatively stiff elbows during stance as opposed to the quite compliant gaits of primates. These finding raise the question of the role of both the mechanical structure of the body and neural control on the determination of these characteristics.
Highlights
Despite the vast variety of quadruped mammals, their locomotion behaviors have a lot in common in terms of gait, kinematics, and neural control [1,2,3,4,5]. Studying these common aspects seems fundamental to the understanding of quadruped locomotion, from the mechanical determinants imposed by physical constraints to the neural control of locomotion
GAIT ANALYSIS Swing and stance durations The crawling gait is characterized by almost synchronous movements between the ipsilateral arm and the contralateral leg
The similarity between the infant standard crawling gait and that of other mammals, especially non-human primates is described by four results
Summary
Despite the vast variety of quadruped mammals, their locomotion behaviors have a lot in common in terms of gait, kinematics, and neural control [1,2,3,4,5]. Studying these common aspects seems fundamental to the understanding of quadruped locomotion, from the mechanical determinants imposed by physical constraints to the neural control of locomotion. Most mammals use very similar gaits that change for different speeds. They have similar periods of flexion and extension of the shoulder and hip, two period flexion/extension of the more peripheral joints, and lateral and sagittal movement of the spine [1, 2, 5, 9]
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