Age-related changes in the activation timing of postural muscles to the prime mover muscle for bilateral arm flexion during standing.

Background: We aimed to obtain the standard values of age-related changes in the activation timing of postural muscles to the prime mover muscle (anterior deltoid [AD]) for bilateral arm flexion during standing.

Methods: The study participants were 276 children (aged 3-14 years) and 32 adults (aged 20-26 years). In response to a visual stimulus, participants raised both arms from a fully extended position as quickly as possible, stopped their arms voluntarily at a horizontal level at the shoulder, and maintained that position for 2 s.

Influence of sports experience on distribution of pro-saccade reaction time under gap condition.

Background: Previous studies indicated that substantial individual variation exists in the distribution of pro-saccade reaction times under gap condition. To investigate the influence of sports experience on the distribution, we examined distribution of the pro-saccade reaction time under overlap and gap conditions, for the basketball club, table tennis club, and non-sporting control groups.

Methods: Subjects performed pro-saccade tasks under the overlap and gap conditions, in which the intentional and reflexive disengagement of fixation are important, respectively.

Developmental changes in shortening of pro-saccade reaction time while maintaining neck flexion position.

Background: We investigated developmental changes in shortening of pro-saccade reaction time while maintaining neck flexion.

Methods: Subjects comprised 135 children (3-14 years) and 29 young adults (19-23 years). Children were divided into six groups in 2-year age strata.

Timings of attentional switching to perturbation and postural preparation during transient forward or backward floor translation.

Background: Relationships between the timings of attentional switching and postural preparation were investigated using a choice-reaction paradigm with transient floor translation (S2), with the direction indicated by a warning auditory signal (S1).

Methods: Thirteen healthy young adults participated in this study. S2 started 2 s after S1 onset while standing on the platform.

Activation timing of postural muscles of lower legs and prediction of postural disturbance during bilateral arm flexion in older adults.

Background: Activation timings of postural muscles of lower legs and prediction of postural disturbance were investigated in young and older adults during bilateral arm flexion in a self-timing task and an oddball task with different probabilities of target presentation. Arm flexion was started from a standing posture with hands suspended 10 cm below the horizontal level in front of the body, in which postural control focused on the ankles is important.

Methods: Fourteen young and 14 older adults raised the arms in response to the target sound signal.

Quantitative analysis of the Trendelenburg test and invention of a modified method.

Background: While the Trendelenburg test has been used for 120 years to detect hip abductor muscle weakness, the methodology has not been standardised.

Purposes: This study undertook to quantitatively analyze the relation between abductor muscle activity and pelvic tilt angle in the Trendelenburg one-leg stance, examine the pitfalls associated with performing the T-test, and develop a modified method that will produce reliable results.

Methods: A convenience sample of 15 healthy males was asked to assume a one-leg stance in ten different postures, five with mild flexion on the unsupported side, and five with severe flexion.

Postural control and contingent negative variation during transient floor translation while standing with the ankle fixed.

Background: Adaptation changes in postural muscle activity and anticipatory attention were investigated with the ankle joint fixed to change postural control strategies during transient floor translation.

Methods: For 15 healthy young adults, 40 transient floor translations (S2) in the anterior direction were applied 2 s after an auditory warning signal (S1), under conditions with or without fixation of the ankle. Activity of the frontal postural muscles (tibialis anterior (TA), rectus femoris (RF), rectus abdominis) and contingent negative variation (CNV, brain potential) were analyzed for 20 trials each of the early and latter halves under each fixation condition.

Event-related brain potential and postural muscle activity during standing on an oscillating table while the knee, hip, and trunk are fixed.

Background: In this study, a cast brace was used to immobilize the knee, hip, and trunk, and relations between the event-related brain potential (ERP) and postural muscle activity were investigated while standing on an oscillating table.

Methods: Twelve healthy young adults maintained a standing posture for 1 min per trial while oscillating in the anteroposterior direction at 0.5 Hz with a 2.

Postural responses to various frequencies of vibration of the triceps surae and forefoot sole during quiet standing.

The purpose of this study was to determine the role of somatosensory input to the sensory reference system in quiet standing. We applied vibration (0.5 mm amplitude, 1-60 Hz) to the triceps surae and the forefoot sole to stimulate the muscle spindles and the mechanoreceptors, respectively, and evaluated postural responses.

Postural control during transient floor translation while standing with the leg and trunk fixed.

Postural movement was restricted above the ankle, and contingent negative variation (CNV) and postural muscle activity were investigated during a transient floor translation (S2) 2s after an auditory warning signal (S1). For 13 healthy young adults, the joints of the knee, hip, and trunk were fixed using a cast brace. Under no-fixation and fixation, a set of 10 translations was repeated at least 4 times, and center of pressure in the anteroposterior direction (CoPap), posterior postural muscle activity of the body (elector spinae (ES), biceps femoris (BF), gastrocnemius (GcM) and soleus (Sol)), and late CNV at Cz were analyzed in the initial two sets (initial set) and last two sets (late set).

Dominant side in single-leg stance stability during floor oscillations at various frequencies.

Background: We investigated lateral dominance in the postural stability of single-leg stance with anteroposterior floor oscillations at various frequencies.

Methods: Thirty adults maintained a single-leg stance on a force platform for 20 seconds per trial. Trials were performed with no oscillation (static condition) and with anteroposterior floor oscillations (2.

Effect of time pressure on attentional shift and anticipatory postural control during unilateral shoulder abduction reactions in an oddball-like paradigm.

Background: The effect of time pressure on attentional shift and anticipatory postural control was investigated during unilateral shoulder abduction reactions in an oddball-like paradigm.

Methods: A cue signal (S1) - imperative signal (S2) sequence was repeated with various S2-S1 intervals (1.0, 1.

Adaptation changes in dynamic postural control and contingent negative variation during repeated transient forward translation in the elderly.

Background: Adaptation changes in postural control and contingent negative variation (CNV) for the elderly were investigated during repeated forward floor translation.

Methods: Fifteen healthy elderly persons, living in the suburban area of Kanazawa City, Japan, underwent backward postural disturbance by a forward-floor translation (S2) 2 s after an auditory warning signal (S1). A set with 20 trials was repeated until a negative peak of late CNV was recognized in the 600-ms period before S2, and the last set was defined as the final set.

Postural responses accompanying Achilles tendon vibration stimulation during various phases of sit-to-stand movement.

The aim of this study was to determine the postural response accompanying Achilles tendon vibration stimulation during various phases of the sit-to-stand movement. Twelve healthy young adults performed the sit-to-stand movement in response to an auditory signal 2 s after a first one. Vibration stimulation with a 100 Hz frequency was applied to both Achilles tendons during the following phases: (1) 10 s of sitting before standing up; (2) 10 s plus a period until the standing position was achieved; and (3) 5 s after standing.

Effect of maintaining neck flexion on anti-saccade reaction time: an investigation using transcranial magnetic stimulation to the frontal oculomotor field.

Background: Reaction time for anti-saccade, in which the gaze is directed to the position opposite to an illuminated target, shortens during maintenance of neck flexion. The present study applied transcranial magnetic stimulation (TMS) to the frontal oculomotor field, and investigated the effect of maintaining neck flexion on information processing time in the anti-saccade neural pathway before the frontal oculomotor field.

Methods: The reaction time was measured with the chin resting on a stand ('chin-on' condition) and with voluntary maintenance of neck flexion ('chin-off' condition) at 80% maximal neck flexion angle, with and without TMS.

Effects of limiting anterior displacement of the center of foot pressure on anticipatory postural control during bilateral shoulder flexion.

In bilateral shoulder flexion with the arms moving from the sides of the body to the horizontal level while standing, no preceding activation of the triceps surae (TS) with respect to focal muscles has been found. Considering that preceding activation would offer a useful indicator of anticipatory postural control, it was attempted to induce preceding activation by limiting the anterior displacement range of the center of foot pressure in the anteroposterior direction (CoPap). Subjects were 13 healthy young adults.

The effects of neck flexion on cerebral potentials evoked by visual, auditory and somatosensory stimuli and focal brain blood flow in related sensory cortices.

Background: A flexed neck posture leads to non-specific activation of the brain. Sensory evoked cerebral potentials and focal brain blood flow have been used to evaluate the activation of the sensory cortex. We investigated the effects of a flexed neck posture on the cerebral potentials evoked by visual, auditory and somatosensory stimuli and focal brain blood flow in the related sensory cortices.

Adaptation changes in dynamic postural control and contingent negative variation during backward disturbance by transient floor translation in the elderly.

Background: We investigated adaptation changes in dynamic postural control and contingent negative variation (CNV) in 13 young and 12 elderly adults. Subjects repeatedly underwent backward postural disturbance by a forward floor translation (S2) 2 s after an auditory warning signal (S1). Initial and second sets were conducted, each set with 20 trials.

Effects of neck flexion on discriminative and cognitive processing in anticipatory postural control during bilateral arm movement.

We investigated the effect of neck flexion on discriminative and cognitive processing in postural control during bilateral arm movement while standing, using event-related potential (ERP) and electromyogram. Fourteen healthy subjects flexed their arms to the target stimuli with a 20% probability in neck resting and flexion positions. Amplitude and latency of N2 and P3, anterior deltoid (AD) reaction time, onset time of postural muscles with respect to AD activation, and peak amplitude and latency of all muscles were measured.

Effects of attentional dispersion on sensory-motor processing of anticipatory postural control during unilateral arm abduction.

Objective: We investigated effects of attentional dispersion on sensory-motor processing of anticipatory postural control during unilateral arm abduction.

Methods: Thirteen adults performed arm abduction under two types of attentional dispersion conditions. A target stimulus was presented with 30% probability in two- or three-positions.

Effects of anticipation certainty on preparatory brain activity and anticipatory postural adjustments associated with voluntary unilateral arm movement while standing.

We examined the effects of anticipation certainty concerning which voluntary movement is required in response to a stimulus while standing on preparatory brain activity and anticipatory postural adjustments (APAs). Ten right-handed adults abducted their left or right arm rapidly in response to a visual imperative stimulus, based on the type of stimulus. A warning cue, which did or did not contain information about the side of arm abduction, was presented 2000ms before the imperative stimulus.

Age-related changes and sex differences in postural control adaptability in children during periodic floor oscillation with eyes closed.

We investigated age-related changes and sex differences in adaptability of anticipatory postural control in children. Subjects comprised 449 children (4-12 years old) and 109 young adults (18-29 years old). Subjects stood with eyes closed on a force-platform fixed to a floor oscillator.

Effects of experimentally induced low back pain on the sit-to-stand movement and electroencephalographic contingent negative variation.

It is becoming increasingly evident that people with chronic, recurrent low back pain (LBP) exhibit changes in cerebrocortical activity that associate with altered postural coordination, suggesting a need for a better understanding of how the experience of LBP alters postural coordination and cerebrocortical activity. To characterize changes in postural coordination and pre-movement cerebrocortical activity related to the experience of acutely induced LBP, 14 healthy participants with no history of LBP performed sit-to-stand movements in 3 sequential conditions: (1) without experimentally induced LBP; NoPain1, (2) with movement-associated LBP induced by electrocutaneous stimulation; Pain, and (3) again without induced LBP; NoPain2. The Pain condition elicited altered muscle activation and redistributed forces under the seat and feet prior to movement, decreased peak vertical force exerted under the feet during weight transfer, longer movement times, as well as decreased and earlier peak hip extension.

Effects of regular heel-raise training aimed at the soleus muscle on dynamic balance associated with arm movement in elderly women.

The effects of low-intensity muscle training with heel-raises on dynamic balance associated with bilateral arm flexion were investigated in postmenopausal elderly women. Twenty-six elderly women were evenly grouped into training and control groups. Training group subjects performed 100 heel raises per day for 2 months.

Activation timing of postural muscles during bilateral arm flexion in self-timing, oddball and simple-reaction tasks.

Background: We investigated the effect of time constraint on activation timing of postural muscles during bilateral arm flexion in self-timing, oddball and simple-reaction tasks.

Methods: Thirteen healthy adults flexed their arms from a suspended position with maximum speed and stopped at the shoulder level. For erector spinae-longissimus (ES), biceps femoris (BF), and gastrocnemius (GcM), onset timing of burst activation with respect to the anterior deltoid (AD), and the displacement of the center of pressure in the anteroposterior direction (CoPy) were analyzed.