The mechanics of walking in children.

Cavagna, G; Franzetti, P.; Fuchimoto, Takafumi

doi:10.1113/jphysiol.1983.sp014895

Cited by 156 publications

(191 citation statements)

References 12 publications

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“…In order to verify that our population sample is representative of normal walking children, we measured walking speed and stride length as standard gait parameters (Cavagna et al 1983;Ledebt et al 1995;Sutherland et al 1980). Exponential functions were fitted to the data either excluding or including the very first steps to verify whether these prefigure the evolution of the rest of the data.…”

Section: Evolution Of Standard Gait Parametersmentioning

confidence: 99%

“…Thus it seems reasonable to hypothesize that children develop kinematic patterns that minimize energy expenditure as they approach adulthood. It is known that, to maintain a given speed, children generally perform a greater amount of work per unit mass per unit time with a greater weight-specific oxygen consumption than the adults (Astrand and Rodahl 1986;Cavagna et al 1983).…”

Section: Mechanics Of Walkingmentioning

confidence: 99%

“…C Relationship between angle θ and pitch (π) and roll (ρ) angles, with correlation coefficients (r) of 0.86 and 0.80 for θ-ρ and θ-π relationships, respectively. Adult means (broken lines) and standard deviations are indexed for θ (a), pitch (a π ) and roll (a ρ ) angles 1985; Thelen and Cooke 1987;Yang et al 1998a, b) and go on long thereafter (Berger et al 1984;Brenière and Bril 1998;Cavagna et al 1983;Cioni et al 1993;Clark and Phillips 1993;Forssberg 1985Forssberg , 1999LaskoMcCarthey et al 1990;Ledebt et al 1995;Leonard et al 1991;Sutherland et al 1980). This is reflected by the gradual acquisition of gait parameters, some of them as early as fetal life (De Vries et al 1984) and some as late as late childhood (Hirschfeld and Forssberg 1992).…”

Section: Mechanics Of Walkingmentioning

confidence: 99%

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Development of a kinematic coordination pattern in toddler locomotion: planar covariation

Chéron

Bouillot

Dan

et al. 2001

Experimental Brain Research

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The purpose of this study is to analyze the coordination patterns of the elevation angles of lower limb segments following the onset of unsupported walking in children and to look for the existence of a planar covariation rule as previously described in adult human locomotion. The kinematic patterns of locomotion were recorded in 21 children (11-144 months of age) and 19 adults. In 4 children we monitored the very first unsupported steps. The extent to which the covariation of thigh, shank, and foot angles was constrained on a plane in 3D space was assessed by means of orthogonal regression and statistically quantified by means of principal component analysis. The orientation of the covariation plane of the children was compared with the mean value of the adults' plane. Trunk stability with respect to the vertical was assessed in both the frontal (roll) and sagittal (pitch) planes. The evolution with walking experience of the plane orientation and trunk oscillations demonstrated biexponential profiles with a relatively fast time constant (<6 months after the onset of unsupported locomotion) followed by a much slower progression toward adult values. The initial fast changes of these walking parameters did not parallel the slow, monotonic maturation of anthropometric parameters. The early emergence of the covariation plane orientation and its correlation with trunk vertical stability reflect the dynamic integration of postural equilibrium and forward propulsion in a gravity-centered frame. The results support the view that the planar covariation reflects a coordinated, centrally controlled behavior, in addition to biomechanical constraints. The refinement of the planar covariation while morphological variables drastically change as the child grows implies a continuous update of the neural command.

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Section: Evolution Of Standard Gait Parametersmentioning

confidence: 99%

Section: Mechanics Of Walkingmentioning

confidence: 99%

Section: Mechanics Of Walkingmentioning

confidence: 99%

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Development of a kinematic coordination pattern in toddler locomotion: planar covariation

Chéron

Bouillot

Dan

et al. 2001

Experimental Brain Research

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“…The mechanical work done during each step in lifting and accelerating the centre of gravity of the body in the forward and vertical directions, W'xt, was measured (347 runs) by means of a platform (4 m long and 0-5 m wide), sensitive to the vertical and forward components of the force exerted by the foot against the ground. The characteristics of this platform, the principle of the method and the procedure followed to compute velocity, displacement and mechanical energy changes of the centre of mass of the body by integration of the force-time platform's records are described in detail by Cavagna (1975) and by Cavagna, Franzetti & Fuchimoto (1983). The mechanical energy changes of the centre of mass of the body are illustrated in the upper part of Fig.…”

Section: Methodsmentioning

confidence: 99%

The two power limits conditioning step frequency in human running.

Cavagna

Willems

Franzetti

et al. 1991

The Journal of Physiology

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SUMMARY1. At high running speeds, the step frequency becomes lower than the apparent natural frequency of the body's bouncing system. This is due to a relative increase of the vertical component of the muscular push and requires a greater power to maintain the motion of the centre of gravity, Wext. However, the reduction of the step frequency leads to a decrease of the power to accelerate the limbs relatively to the centre of gravity, Wint, and, possibly, of the total power Wtot -Wext + Wint -2. In this study we measured Wext using a force platform, Wint by motion picture analysis, and calculated WtOt during human running at six given speeds (from 5 to 21 km h-') maintained with different step frequencies dictated by a metronome. The power was calculated by dividing the positive work done at each step by the duration of the step (step-average power) and by the duration of the positive work phase (push-average power).3. Also in running, as in walking, a change of the step frequency at a given speed has opposite effects on Wext5 which decreases with increasing step frequency, and Wint, which increases with frequency; in addition, a step frequency exists at which Wtot reaches a minimum. However, the frequency for a minimum of WtOt decreases with speed in running, whereas it increases with speed in walking. This is true for both the step-average and the push-average powers. 4. The frequency minimizing the step-average power equals the freely chosen step frequency at about 13 km h-': it is higher at lower speeds and lower at higher speeds. The frequency minimizing the push-average power approaches the freely chosen step frequency at high speeds (around 22 km h-' for our subjects).5. It is concluded that the increase of the vertical push does reduce the stepaverage power, but that a limit is set by the increase of the push-average power. Between 13 and 22 km h-' the freely chosen step frequency is intermediate between a frequency minimizing the step-average power, eventually limited by the maximum oxygen intake (aerobic power), and a frequency minimizing the push-average power, set free by the muscle immediately during contraction (anaerobic power). The first need prevails at the lower speed, the second at the higher speed.

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“…The procedure followed to determine the curves in Figure 6 and 7, and the external work, has been described in detail in several studies [34][35][36]. In short: the horizontal force and the vertical force minus the body weight were integrated electronically to determine the instantaneous velocity of the center of mass of the body to yield the instantaneous kinetic energy, E k = E kf + E kv .…”

Section: External Workmentioning

confidence: 99%

Symmetry and Asymmetry in Bouncing Gaits

Cavagna

2010

Symmetry

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Abstract:In running, hopping and trotting gaits, the center of mass of the body oscillates each step below and above an equilibrium position where the vertical force on the ground equals body weight. In trotting and low speed human running, the average vertical acceleration of the center of mass during the lower part of the oscillation equals that of the upper part, the duration of the lower part equals that of the upper part and the step frequency equals the resonant frequency of the bouncing system: we define this as on-offground symmetric rebound. In hopping and high speed human running, the average vertical acceleration of the center of mass during the lower part of the oscillation exceeds that of the upper part, the duration of the upper part exceeds that of the lower part and the step frequency is lower than the resonant frequency of the bouncing system: we define this as on-off-ground asymmetric rebound. Here we examine the physical and physiological constraints resulting in this on-off-ground symmetry and asymmetry of the rebound. Furthermore, the average force exerted during the brake when the body decelerates downwards and forwards is greater than that exerted during the push when the body is reaccelerated upwards and forwards. This landing-takeoff asymmetry, which would be nil in the elastic rebound of the symmetric spring-mass model for running and hopping, suggests a less efficient elastic energy storage and recovery during the bouncing step. During hopping, running and trotting the landing-takeoff asymmetry and the mass-specific vertical stiffness are smaller in larger animals than in the smaller animals suggesting a more efficient rebound in larger animals.

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The mechanics of walking in children.

Cited by 156 publications

References 12 publications

Development of a kinematic coordination pattern in toddler locomotion: planar covariation

Development of a kinematic coordination pattern in toddler locomotion: planar covariation

The two power limits conditioning step frequency in human running.

Symmetry and Asymmetry in Bouncing Gaits

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