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The purpose of this study was to describe the force/velocity and power/velocity relationships obtained during squat exercise. The maximal force (F0) was extrapolated from the force/velocity relationship and compared to the isometric force directly measured with the aid of a force platform placed under the subject's feet. Fifteen international downhill(More)
The spring-mass model, representing a runner as a point mass supported by a single linear leg spring, has been a widely used concept in studies on running and bouncing mechanics. However, the measurement of leg and vertical stiffness has previously required force platforms and high-speed kinematic measurement systems that are costly and difficult to handle(More)
The objective of the study was to examine whether and how an additional load affects the Anticipatory Postural Adjustments (APA) in gait initiation in able-bodied individuals. Nineteen healthy participants initiated gait at a self-selected speed in two conditions: unloaded and with an overload of 15% body weight. The APA duration, the forward impulse of the(More)
A new method to measure the leg stiffness in hopping and bouncing, with simple technical equipment and under field conditions, is introduced and validated. The leg stiffness (K (N)) was calculated from only contact and flight times measured by a contact mat. It was compared to the reference stiffness (K (R)) obtained from force platform measurements. Eight(More)
This study investigated the influence of gait speed on the control of mediolateral dynamic stability during gait initiation. Thirteen healthy young adults initiated gait at three self-selected speeds: Slow, Normal and Fast. The results indicated that the duration of anticipatory postural adjustments (APA) decreased from Slow to Fast, i.e. the time allocated(More)
Adolescent idiopathic scoliosis girls are known to display standing imbalance. In addition to a motor deficit problem, the axial torsion of the spine and trunk torsion could reflect an imbalance around the vertical axis. Unlike the excursion of the center of pressure (COP), the forces and moments were rarely addressed to characterize the quiet standing(More)
This study investigated the accuracy and reliability of four methods using force-plate data for detecting the swing heel-off (HO) time in gait initiation. Results of these methods were compared to those obtained by means of a reference method using a footswitch. Ten young healthy adults performed 18 forward gait initiation trials at self-selected speed and(More)
This study was done to determine whether leg stiffness (Kleg) during running was related to rearfoot-to-forefoot angle in standing (RFAst) and running (RFArun). Footprints obtained from 32 subjects were used to calculate RFAst and RFArun, defined as positive when forefoot axis was abducted from rearfoot axis. A spring-mass model was used to calculate Kleg(More)
Adolescent idiopathic scoliosis (AIS) is the most common form of scoliosis and usually affects young girls. Studies mostly describe the differences between scoliotic and non-scoliotic girls and focus primarily on a single set of parameters derived from spinal and pelvis morphology, posture or standing imbalance. No study addressed all these three(More)
In adolescent idiopathic scoliotic girls, postural imbalance is attributed to a sensory rearrangement of the motor system on the representation of the body in space. The objectives of this study were to test if the anteroposterior (AP), mediolateral (ML) and resultant body-head and trunk center of mass (COM) horizontal offsets were similar in able-bodied(More)