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Thomas A. Stoffregen

It is widely assumed that healthy aging includes a decline in the stability of standing body sway. Certainly, the spatial magnitude of postural sway increases with age. However, the interpretation of this effect as a decline in the ability to stabilize posture rests, in part, on assumptions about the nature and definition of stability in stance. In this article, I review data on the control of standing posture in healthy older adults. I focus on a growing list of studies that demonstrate the retention, among healthy older adults, of the ability functionally to modulate postural sway in support of “suprapostural” activities. I address laboratory research, but also field studies carried out in a setting that dramatically challenges the control of stance: life on ships at sea. I argue that it may be possible, and certainly will be useful, to address directly the functional control of stance in older adults.

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Fawaz A. Alwadani, Huaqing Liang and Alexander S. Aruin

The central nervous system assimilates afferent sensory inputs from the visual, proprioceptive, and vestibular systems to maintain a stable bipedal stance ( Ivanenko & Gurfinkel, 2018 ; Massion, 1994 ). When standing still, the vertical projection of the center of gravity rests anteriorly to the

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Semyon M. Slobounov and Karl M. Newell

This study provides a comparative analysis of certain features of upright and inverted stance in collegiate-level competitive gymnastic and diving athletes. A particular focus was the compensatory movement strategies used to maintain inverted stance. The analyses revealed that the motion of the center of pressure was significantly greater in the hand stance as opposed to the upright stance condition. Instability increased over the duration of a 15-s hand stance trial, and it was paralleled by the introduction of a small set of compensatory movement strategies that included enhanced motion at the distal segments of the legs and at the elbow joint. The compensatory movement strategies appeared to be in support of minimizing variability of motion in the head and trunk. The relative contribution of the principal sources of this instability in the hand stance remains to be determined.

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Marianne J.R. Gittoes and Cassie Wilson

This study aimed to develop insight into the lower extremity joint coupling motions used in the maximal velocity phase of sprint running. Two-dimensional coordinate data were used to derive sagittal plane joint angle profiles of sprint running trials. Intralimb joint coupling motions were examined using a continuous relative phase (CRP) analysis. The knee-ankle (KA) coupling was more out of phase compared with the hip-knee (HK) coupling across the step phase (mean CRP: KA 89.9° HK 34.2°) and produced a lower within-athlete CRP variability (VCRP) in stance. Touchdown (TD) produced more out-of-phase motions and a larger VCRP than toe-off. A destabilization of the lower extremity coordination pattern was considered necessary at TD to allow for the swing-to-stance transition. The key role that the KA joint motion has in the movement patterns used by healthy athletes in the maximal velocity phase of sprint running was highlighted.

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Masakazu Matsuoka, Hiroshi Kunimura and Koichi Hiraoka

Humans respond to translation of the support surface under their feet in stance to maintain the center of pressure within the base of support (see Jacobs et al., 2008 ; Jacobs & Horak, 2007 ; Massion, 1994 ). This response is produced by activity of the limb and trunk muscles ( Horak & Nashner

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Patrice R. Rougier, Thibaud Coquard, Thierry Paillard, Clément Ankaoua, Jeanne Dury, Corentin Barthod and Dominic Perennou

statistically significant effect was, however, reported for LU and PD mechanisms between these two feet positions ( Rougier, 2008 ). Our objective in that study was to assess to which extent the postural control strategies, previously reported for characterizing upright stance maintenance with WBA on solid

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Scott Ross, Kevin Guskiewicz, William Prentice, Robert Schneider and Bing Yu

Objective:

T o determine differences between contralateral limbs’ strength, proprio-ception, and kinetic and knee-kinematic variables during single-limb landing.

Setting:

Laboratory.

Subjects:

30.

Measurements:

Hip, knee, and foot isokinetic peak torques; anterior/posterior (AP) and medial/lateral (ML) sway displacements during a balance task; and stabilization times, vertical ground-reaction force (VGRF), time to peak VGRF, and knee-flexion range of motion (ROM) from initial foot contact to peak VGRF during single-limb landing.

Results:

The kicking limb had significantly greater values for knee-extension (P = .008) and -flexion (P = .047) peak torques, AP sway displacement (P = .010), knee-flexion ROM from initial foot contact to peak VGRF (P < .001), and time to peak VGRF (P = .004). No other dependent measures were significantly different between limbs (P > .05).

Conclusion:

The kicking limb had superior thigh strength, better proprioception, and greater knee-flexion ROM than the stance limb.

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Stacy E. Stamm and Loren Z.F. Chiu

When the rear- and forefoot are constrained, calcaneal plantar flexion may occur, deforming the longitudinal arch. Previous research has reported calcaneal motion relative to the tibia or forefoot; these joint rotations may not accurately describe rotation of the calcaneus alone. This investigation: (1) characterized the calcaneus and leg segment and ankle joint rotations during stance in gait, and (2) described the range of calcaneal plantar flexion in different structural arch types. Men (n = 14) and women (n = 16) performed gait in a motion analysis laboratory. From heel strike to heel off, the leg rotated forward while the calcaneus plantar flexed. Before foot flat, calcaneal plantar flexion was greater than forward leg rotation, resulting in ankle plantar flexion. After foot flat, forward leg rotation was greater than calcaneal plantar flexion, resulting in ankle dorsiflexion. Structural arch type was classified using the longitudinal arch angle. The range of calcaneal plantar flexion from foot flat to heel off was small in low (−2° to −8°), moderate in high (−3° to −12°), and large in normal (−2° to −20°) structural arches. Calcaneal plantar flexion in gait during midstance may reflect functional arch characteristics, which vary depending on structural arch type.

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Dawn M. Corbin, Joseph M. Hart, Patrick O. McKeon, Christopher D. Ingersoll and Jay Hertel

Context:

Increased plantar cutaneous afferent information may improve postural control.

Objective:

To compare postural control measures between balance conditions with and without textured insoles.

Design:

crossover trial.

Setting:

Research Laboratory.

Patients or Other Participants:

33 healthy subjects (27.4 ± 9.1yrs, 172.6 ± 10.3 cm, 75.4 ± 16.4 kg).

Intervention(s):

Subjects performed 24, 10-second bipedal and unilateral stance balance trials with eyes opened and eyes closed, with and without a textured insole in subjects’ shoes.

Main Outcome Measures:

Average velocity and area of center of pressure (COP) excursions.

Results:

We observed an interaction among balance conditions during bilateral stance, but not during unilateral stance. On average, subjects exhibited greater area and velocity of COP excursions with eyes closed compared to eyes opened. Significant differences in area and velocity of COP excursions were observed during bilateral stance only when subjects were not wearing textured insoles. There were no significant differences while subjects balanced in bilateral stance with textured insoles.

Conclusions:

Increased afferent information from textured insoles improves postural control in bilateral stance.

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Annick Ledebt, Jules Becher, Janneke Kapper, Rianne M. Rozendaal, Rachel Bakker, Iris C. Leenders and Geert J.P. Savelsbergh

The aim of the present study was to examine the effects of balance training with visual feedback on stance and gait in school-age children with hemiplegic cerebral palsy. Ten participants between 5 and 11 years of age were assigned to either the training or the control group according to an aged-stratified randomization. The training corresponded to three sessions per week during six weeks. Stance and gait parameters, based on force plate data, were assessed three times in both groups: (a) at the beginning of the study (before training); (b) after six weeks; (c) after ten weeks. Spatial and temporal parameters were calculated. The results for stance showed that the training improved the performances on the tasks that were trained. More interesting, the results for gait showed that the walking pattern became more symmetrical after the training.