睡眠时体位对儿童阻塞性睡眠呼吸暂停低通气综合征的影响

目的评估阻塞性睡眠呼吸暂停低通气综合征(OSAHS)患儿与正常儿童在睡眠时体位上的差异及体位对儿童睡眠呼吸紊乱的影响。方法比较358例经多导睡眠检测(PSG)诊断为OSAHS的儿童(OSAHS组)与161例在年龄、性别上相匹配的儿童(对照组)的PSG结果,并进一步比较睡眠时不同体位对睡眠呼吸暂停低通气指数(AHI)和暂停指数(AI)的影响。结果睡眠时OS-AHS组儿童采用仰卧位、侧卧位和俯卧位的时间占总的睡眠时间的百分比分别为45·4%±36·3%、39·5%±34·5%和15·1%±32·6%,而对照组则分别为32·8%±24·5%、54·7%±23·9%和12·5%±17·2%。OSAHS组仰卧位睡眠时间比对照组儿童明显增加(P<0·01),侧卧位的时间明显减少(P<0·01),但俯卧位的睡眠时间没有差异(P>0·05)。OSAHS组在3种不同体位睡眠时平均AHI为14·5/h,平均阻塞性AI为3·80/h。仰卧位时的AHI和AI较侧卧位和俯卧位时明显增加(P<0·01),而对照组的AHI和AI在3种睡眠体位中无明显差异。结论睡眠时,OSAHS儿童更多采用仰卧位,提示这种体位可能是促使OSAHS儿童发生上气道阻塞的原因。     

Electrocortical activity during stretch reflex in athletes

Background

To evaluate timing and characteristics of electrocortical activity during stretch reflex evocation of the quadriceps femoris at different body postures.

Methods

Twenty athletes were subjected to reflex hammer percussions on patellar tendon, in a random time sequence, in seated and supine decubitus postures. 745 ms of acquisition were evaluated for data analysis: 200 ms of pre-stimulation, 45 ms relative to the elapsed time from stimulation to the end of the muscular contraction, and 500 ms of post-stimulation. First, a scalp-map analysis, considering channels data, was performed; second, independent component analysis decomposition was applied to all 16 channels. To highlight the differences among two conditions (pre- and post-stimulation) and two sessions (seated and supine decubitus postures), a two-way analysis of variance was used. Time–frequency analysis has been applied to identify the density of the frequencies as a function of the time, instant by instant.

Results

Fast alpha, beta, and gamma frequency bands showed a greater electroencephalographic activity after the stimulation. Seated posture showed a greater activation than the decubitus supine posture. Time frequency analysis highlighted an higher electrocortical activation for 160 ms as well as from about 250–300 ms at all frequency bands after the stimulation.

Conclusions

Our findings improve the understanding of the neurophysiological dynamics following the stretch reflex after concussion of the patellar tendon, executed in different postures, considering scalp-map, power spectra, and timing of activation. The use of scalp-map and power spectra analysis techniques represents a sophisticated use of advanced signal processing methodologies to analyze brain activity during movement and in specificity in sport science.

     

复杂度在立位期间心率变异分析中的应用

目的 介绍非线性指标复杂度,并将之应用于心率变异分析。分析立位测试过程中心血管系统复杂性的变化。方法 对8名被试者进行立位耐力测试。记录心电信号并用复杂度进行心率变异分析。结果 与立位前平卧位相比,立位0-5min,5-10min,10-15min和15-20min心脏R-R间期,R-R间期标准差和相临R-R间期差值的标准差（RMSSD）显著降低。立位0-5min,15-20min复杂度和近似熵显著低于平卧位。结论 立位期间心率变异降低。心血管系统复杂性降低。复杂度应用于心率变异的分析是可行的。     

Abnormality of standing posture improves in patients with bilateral spastic cerebral palsy following lower limb surgery

ObjectivesThe degree of abnormality of the gait pattern of children with bilateral spastic cerebral palsy (BSCP) can be reduced by lower limb orthopaedic surgery. However, little attention is paid to the effects of surgery on standing posture. Here, we investigated the abnormality of standing posture in young people with BSCP as well as the effects of surgery on standing posture.MethodsWe have developed an index of standing posture, the Standing Posture Score (SPS), which is similar in composition to the gait profile score (GPS). We applied SPS retrospectively to 32 typically developing children and 85 children with BSCP before and after surgery to the lower limbs aimed at improving gait. We investigated the relationship between SPS and GPS before surgery and also the relationship between changes in these variables before and after surgery.ResultsSPS is significantly higher in young people with BSCP. SPS reduces after surgery and this reduction is correlated with the reduction in GPS.InterpretationSuccessful surgery improves the alignment of the lower limbs in BSCP in standing and may have a positive impact on the activities of daily living which depend on a stable and efficient standing posture.     

近似熵及其在心率变异分析中的应用

目的：介绍近似熵;并将之应用于心率变异分析,分析立位测试过程中心血管系统复杂性的变化。方法：对８名被试者进行立位耐力测试,记录心电信号并用近似熵进行心率变异分析。结果：与立位前平卧位相比,立位０￣５ｍｉｎ、５￣１０ｍｉｎ、１０￣１５ｍｉｎ和１５￣２０ｍｉｎ心脏Ｒ－Ｒ间期显著降低,而立位０￣５ｍｉｎ近似熵显著低于平卧位和立位１５￣２０ｍｉｎ,立位１５￣２０ｍｉｎ近似熵显著低于平卧位,说明立位测试过程中心血管系统复杂性降低,心血管系统的调节模式有改变。结论：近似熵应用于心率变异的分析是可行的。     

Influence of thoracic posture on scapulothoracic and glenohumeral motions during eccentric shoulder external rotation

BackgroundThrowing injuries to the shoulder joint often occur during shoulder external rotation. An appropriate combination of thoracic, scapular, and humeral motion during throwing is important to prevent such injuries, but it is unclear how thoracic posture contributes to shoulder motion during throwing.Research questionThe purpose of this study, therefore, was to clarify the influence of thoracic posture on scapulothoracic and glenohumeral motion during shoulder external rotation.MethodsEccentric external rotation at 90° of shoulder abduction in thoracic flexion and extension postures was performed by 15 asymptomatic participants. Three-dimensional scapulothoracic and glenohumeral movements were measured with an electromagnetic tracking device at 75°, 80°, 85°, and maximum shoulder external rotation. The thoracic angle and maximum shoulder external rotation in absolute coordination were measured with a three-dimensional motion capture system.ResultsThe results showed that scapular posterior tilting and external rotation in the thoracic extension posture were significantly greater than those in the flexion posture (p < 0.05). Glenohumeral horizontal extension was significantly less in the thoracic extension posture than in the flexion posture (p < 0.05), whereas maximum shoulder external rotation was significantly greater (p < 0.01). Thus, thoracic extension increased scapulothoracic posterior tilting and external rotation and reduced glenohumeral horizontal extension during shoulder external rotation, as well as increasing maximum shoulder external rotation.SignificanceThese findings suggest that thoracic extension may contribute to reduction of mechanical demand in the glenohumeral joint during throwing, potentially reducing shoulder injuries.     

The influence of smartphone use on spinal posture – A laboratory study

BackgroundSmartphones have become increasingly more popular and complicated tasks can be performed with these devices. However, the increasing use is associated with shoulder and neck pain, as well as with psychological addiction.Research questionDo different smartphone tasks lead to changes in spinal posture and pelvic position? Is there a relationship between smartphone addiction and changes in posture?MethodsA cross-sectional study including 50 participants was performed. Test subjects completed the Smartphone Addiction Scale and the SF-36 health questionnaire. Subjects spinal posture and pelvic position during different smartphone tasks were measured through a surface topography system. The different tasks were: standing in an upright position, simulating a phone call, texting with one or two hands during standing or while walking on a treadmill. Paired T-tests and ANOVA tests were performed to evaluate differences. The Kendall rank test was used to investigate the association between clinical scores and changes in spinal posture.ResultsAll smartphone tasks lead to a significant increase in thoracic kyphosis and trunk inclination during standing and while walking. A significant increased lumbar lordosis was also found. Texting with one or two hands correlated with increased surface rotation. No associations between smartphone addiction and changes of the spinal posture were reported.SignificanceThis represents the first surface topography study that investigated the influence of different smartphone tasks on the spinal posture and pelvic position during standing and while walking. With the results of this study we demonstrated that smartphone use leads to significant changes of sagittal and frontal spine parameters. Further research should focus on the evaluation of possible detrimental effects of long-term smartphone use on the spinal posture and on the development of preventive measures.     

Auditory cues behind congenitally blind subjects improve their balance control in bipedal upright posture

BackgroundCongenitally blind subjects developed postural adaptations improving somatosensory and vestibular systems to maintain upright stability and auditory skills to orient them in environment. However, the influence of auditory cues on upright stability in congenitally blind subjects stays unknown.Research questionThe aim of this study is to define the influence of an auditory cue in congenitally blind subjects back space on their balance posture.MethodsEleven sighted subjects and eleven congenitally blind subjects performed upright bipedal and unipedal quiet stances on a force plate with two conditions of auditory cue played by a loudspeaker placed 2 m behind them. Mean CoP velocity were recorded. Student test was used to compare significant difference between blind and sighted subjects bipedal and unipedal postures stability in both conditions of auditory cue.Results and significanceResults showed that congenitally blind subjects had no significant difference in mean sway velocity compared to sighted subjects in bipedal upright posture in auditory signal condition. However, blind subjects had significant lower mean sway velocity than sighted subjects in bipedal upright posture without sound. Blind subjects had significant increased mean sway velocity during unipedal quiet standing in both auditory cue conditions (with and without sound). The results showed that congenitally blind subjects used auditory cues placed behind them in order to improve their balance control in bipedal upright posture. In this case, blind subjects could better use compensatory mechanisms to perform quiet standing as sighted subjects. Without sound or in unipedal upright posture, congenitally blind subjects probably have sensory perturbations or limitations that impose them adaptations in order to avoid falling risk. Auditory cues should be study in the aim to better understand the compensatory mechanisms used by congenitally blind subjects to perform postural balance in usual environment.     

Differences in body positional bilateral symmetry between stance and supine positions,and the impact of attention and awareness on postural symmetry

Background and purposePostural asymmetries may cause structural pathological conditions and impaired movement pattern. The influence of body position and awareness towards symmetry has not yet been elucidated. The aim of this study was twofold: First, to compare the body positional bilateral symmetry between standing and supine positions, and second, to examine whether the awareness to symmetry can modify posture perception and body positional bilateral symmetry.MethodsWe analyzed the degree of anterior postural alignment symmetry of 34 healthy subjects by photogrammetric method (three photographs in a standing position and three in a supine position). Each photo captured different state of awareness: Subjective Comfortable Posture (SCP), Subjective Perceived Symmetrical Posture (SPSP), and Guided Posture Protocol (GPP).ResultsThe standing position increased the symmetrical alignment of the neck (p < 0.013) and the upper limbs (p < 0.011). However, the supine position demonstrated increased symmetrical alignment of the upper trunk (p < 0.019) and the feet (p < 0.002). In the standing position, GPP showed greater symmetry of the neck (p < 0.022), the shoulders (p < 0.014), the thorax midline (p < 0.009), the upper trunk (p < 0.000) and the upper limbs (p < 0.029). No significant changes were observed in the supine position between the three states of awareness.ConclusionsStudy results indicate that the supine position shows greater degree of upper trunk's symmetrical alignment than the standing position. It also indicates that while standing, focusing attention into symmetry improves body positional bilateral symmetry. These results might have clinical implications when working with patients who suffer from asymmetric posture.     

The effect of modifying foot progression angle on the knee loading parameters in healthy participants with different static foot postures

BackgroundStudies have found that toe-in gait reduced the peak knee adduction moment (KAM) during early stance, while toe-out gait reduced the peak KAM during late stance. However, some other studies found that toe-in or toe-out gait could reduce the KAM throughout stance phase. There is still a divergence of opinion on the use of toe-in or toe-out gait for reducing the KAM.Research questionThis study aimed to investigate whether static foot posture affected participants’ biomechanical responses to three self-selected foot progression angles (FPA): neutral, toe-out and toe-in.MethodsTwenty-seven healthy participants were recruited for this FPA gait modification experiment and classified into three groups: neutral (n = 8), supination (n = 9) and pronation (n = 10), based on the Foot Posture Index (FPI). The kinematic and kinetic data were recorded with Vicon motion capture system and three force plates. The knee adduction moment and ankle eversion moment were calculated using an inverse dynamics model. The effect of the FPA modification on the knee loading parameters was analysed by the Friedman non-parametric test.ResultsThe KAM results in the neutral group showed that the toe-in gait modification reduced the first peak of the KAM (KAM1), while the KAM1 was increased in the supination group. The effect of the FPA modification on the KAM1 did not reach significance in the pronation group. The toe-out gait modification reduced the second peak (KAM2) regardless of the static posture.SignificanceDifferent static foot postures were correlated with different peak KAM during the early stance phase due to FPA modification. These data suggest that the assessment of static foot posture provides a reference on how to offer adequate FPA modification for knee OA patients with different foot postures.     

Sagittal standing posture and relationships with anthropometrics and body composition during childhood

BackgroundAnthropometry and body composition are plausible influences on pediatric sagittal standing posture. Despite that, the relationship of anthropometrics since birth and body composition with individual postural parameters in children has never been assessed.Research questionTo assess the associations between anthropometrics since birth and body composition parameters, and angles of sagittal standing posture in children.MethodsThe sample included 1021 girls and 1096 boys, evaluated in the population-based birth cohort Generation XXI, Portugal. Weight and height were obtained at birth, 4 and 7 years of age. At age 7, total body less head fat/fat-free mass and bone properties were estimated from whole body dual energy X-ray absorptiometry scans and posture was assessed through right-side photographs during habitual standing with retro-reflective markers placed on body landmarks.ResultsGirls showed increased values of lumbar angle, head and neck flexion, and craniocervical angle with the largest mean (standard deviation) difference in lumbar angle [281.7° (7.4) vs. 276.8° (7.1) in boys, p < 0.001]. In both genders, weight and body mass index were weakly associated with lumbar angle: 0.24 ≥ r ≤ 0.31 in girls and 0.16 ≥ r ≤ 0.26 in boys, all p < 0.001. Fat and fat-free mass and bone mineral density were weakly associated with lumbar angle in both genders.SignificanceOur study showed clear postural heterogeneity between girls and boys in early ages. Lumbar angle is likely to be the single most relevant proxy of overall posture based on the associations with the exposures reported in this study.     

Self-selection of gestational lumbopelvic posture and bipedal evolution

BackgroundNot all pregnant women seem to select the more curved lumbopelvic posture that their sexual dimorphic anatomy allows even though many previous researchers have assumed lumbopelvic curvature to be standard during pregnancy. This study is vital to understanding coevolution of lumbopelvic sexual dimorphism and bipedalism, and understanding some clinical implications of intervening in gestational posture changes.Research questionsAre there anthropometric changes that correspond with selection of lumbopelvic curvature change during pregnancy? What are the biomechanical costs and benefits of gestational lumbopelvic curvature change?MethodsTwenty pregnant women were tested at five different times in the 2nd and 3rd trimesters of pregnancy. Lumbopelvic posture, standing kinetics and gait kinetics were measured longitudinally. Additionally, we modeled the effects on standing and gait without lumbopelvic postural changes, but with anthropometric changes, for each individual.ResultsWe found greater lumbopelvic angulation to correspond with a shorter body height (6 cm difference between groups, p = 0.048) and deeper 2nd trimester abdomen (2 cm difference between groups, p = 0.013). Lumbopelvic angulation lowers support requirements (in standing and walking (6% lower support impulse, p = 0.056), but at the cost of shifting the propulsive actions to a less efficient pulling action rather than pushoff (13 % reduction in pushoff time, p = 0.001). We observed minimal effects on walking kinematics and balance control.SignificanceOur findings suggest the evolutionary advantage of the female lumbopelvic unit is the adaptability it provides to adjust for the individual needs of the pregnant woman. We discuss multiple potential contributing factors that may have shaped hominin female lumbopelvic evolution and are involved in self-selecting lumbopelvic posture.     

Intertask comparison of frontal plane knee position and moment in female athletes during three distinct movement tasks

Gender differences in dynamic frontal plane knee posture during functional tasks contribute to increased anterior cruciate ligament injury risk in female athletes. Many tasks have been used to assess frontal plane movement patterns, but few studies compare patterns across tasks or evaluate the influence of static alignment on dynamic postures. The purpose of our study was to (1) establish the intertask differences in frontal plane knee posture during step down, single leg land, and drop vertical jump tasks; (2) determine intra‐athlete correlations in knee posture across tasks; and (3) investigate the intra‐athlete correlations between frontal plane knee posture while standing and during movement. Thirty‐seven female athletes from high demand sports participated in a motion analysis assessment. Substantial differences in the frontal plane knee angles and moments occurred between tasks. However, there were strong relationships in frontal plane knee angles (r=0.72–0.76) and moderate to good relationships in knee moments across tasks (r=0.426–0.627). No relationship existed between the standing and dynamic knee abduction angles (r<0.06). Female athletes who demonstrate at‐risk knee position and loading are likely to do so across tasks. The lack of relationship between static and dynamic frontal plane knee posture suggests that neuromuscular mechanisms contribute to the consistency in movement patterns across tasks.     

Effects of compression tights on calf muscle oxygenation and venous pooling during quiet resting in supine and standing positions

AIM: We applied near-infrared spectroscopy (NIRS) to evaluate in resting conditions the effects of compression tights (CT) on calf muscle oxygenation and venous pooling compared with Lycra(R) elastic tights (ET) and shorts (no compression) according to the body posture (supine vs standing). METHODS: Twelve sportsmen regularly involved in endurance training volunteered to this study. Their average age, height and weight (+/-SD) were 26.5+/-2.6 years, 177+/-6 cm and 70.1+/-4 kg, respectively. Tissue oxygenation index (TOI), deoxyhemoglobin (HHb), and blood pooling (Hbtot) of the right gastrocnemius medialis were continuously monitored at 2 Hz using a NIRS device (NIRO-300, Hamamatsu Photonics, Japan). A home made transducer was used to measure applied pressure at the interface between skin and clothing over the calf area. Subjects were asked to realize a supine-standing protocol (5 min for each position) by wearing CT, ET or shorts in a counterbalanced order on the same day. RESULTS: HHb and Hbtot concentration changes were significantly lower whereas TOI was significantly higher by wearing CT compared with shorts and ET (P<0.001) as did supine compared to upright postures. The mean pressures applied over the calf were 5.6 and 23.2 mmHg during supine and 5 and 24.1 mmHg during standing for ET and CT, respectively. Pressures were significantly different among clothing according to the following rank order: CT>ET>shorts (P<0.001). CONCLUSIONS: CT compared to ET have positive effects on calf muscle oxygenation and venous pooling in quiet resting positions.     

Effect of low back posture on the morphology of the spinal canal

Objective. To define the possible mechanism of posture-dependent symptoms of spinal stenosis by measuring the effect of low back posture on morphologic changes of the intervertebral discs and spinal canal in healthy young people. Design.Twenty healthy young volunteers underwent magnetic resonance imaging while supine with their spine in neutral, flexed, extended, and right and left rotational positions. The axial MR images at the middle of the intervertebral discs of L3–4 and L4–5 were analyzed to measure the difference in the size and shape of the intervertebral discs and spinal canal in each posture. Results.  Extension or rotation decreased the sagittal diameters and cross-sectional areas of the dural sac and spinal canal and increased the thickness of the ligamentum flavum, whereas flexion had the opposite effects. The gap between the convex posterior disc margin and the anterior margin of the facet joint on each side, represented as the subarticular sagittal diameter, increased with flexion and decreased with extension or rotation. The direction of rotation did not result in asymmetry of the subarticular sagittal diameter, but right rotation caused thickening of the right ligamentum flavum, and vice versa. The shape and dimensions of the disc did not change significantly according to the positions of the low back. Conclusions.With extension or rotation, the thickness of the ligamentum flavum increased and the posterior margin of the intervertebral disc was approximated to the facet joint without any change in shape and size of the disc. These phenomena result in a decrease in the size of the spinal canal and dural sac in extension or rotation postures in young healthy people without disc degeneration, and may explain the posture-dependent symptom of spinal stenosis. Received: 18 October 1999 Revision requested: 9 November 1999 Revision received: 13 December 1999 Accepted: 17 January 2000     

Validity of the ActivPAL monitor to distinguish postures: A systematic review

BackgroundPosture has been recently integrated into activity guidelines, advising people to limit their sedentary time and break up sedentary postures with standing/stepping as much as possible. The thigh-worn activPAL is a frequently used objective measure of posture, but its validity has only been investigated by individual studies and has not been systematically reviewed.Research QuestionCan the activPAL accurately characterize different postures?MethodsA rigorous systematic review protocol was conducted, including multiple study screeners and determiners of study quality. To be included, validation studies had to examine the accuracy of an activPAL posture outcome relative to a criterion measure (e.g., direct observation) in adults (>18 years). Citations were not restricted to language or date of publication. Sources were searched on May 16, 2021 and included Scopus, EMBASE, MEDLINE, CINAHL, and Academic Search Premier. The study was pre-registered in Prospero (ID# CRD42021248240). Study quality was determined using a modified Hagströmer Bowles checklist. The results are presented narratively.ResultsTwenty-four studies (18 semi-structured laboratory arms, 8 uncontrolled protocol arms; 476 participants) met the inclusion criteria. Some studies (5/24) incorporated dual-monitor (trunk: 4/5; shin: 1/5) configurations. While heterogenous statistical procedures were implemented, most studies (n = 22/24) demonstrated a high validity (e.g., percent agreement >90%, no fixed bias, etc.) of the activPAL to measure sedentary and/or upright postures across semi-structured (17/18 arms) and uncontrolled study designs (7/8 arms). Specific experimental protocol factors (i.e., seat height, fidgeting, non-direct observation criterion comparator) likely explain the divergent reports that observed valid versus invalid findings. The study quality was 11.3 (standard deviation: 2.3) out of 19.ConclusionDespite heterogeneous methodological and statistical approaches, the included studies generally provide supporting evidence that the activPAL can accurately distinguish between sedentary and standing postures. Multiple activPAL monitor configurations (e.g., thigh and torso) are needed to better characterize sitting versus lying postures.     

Effects of bag holding with one hand on lower leg muscles and postural control

Abstract This study examined the influence of holding a load with one hand on the tissue oxygenation kinetics in the flexor digitorum superficialis muscle of the forearm, the electromyographic responses in the lower leg antigravity muscles, and the center of foot pressure (COP) sway. Ten healthy young men participated in this study. They kept an upright standing posture while holding a load with the dominant hand under four load weight conditions (0%, 15%, 30%, and 45% of maximal voluntary contraction (MVC) of the jerk strength). Sway factors were mainly significantly higher at 45% MVC than the other conditions. There was little relationship between tissue oxygenation kinetics in the forearm and COP sway during upright standing posture. Holding a load below 30% MVC did not affect postural stability. When holding a 45% MVC load, activities of the antigravity muscles of the lower leg on the side holding bag largely increased, fatigue in antigravity muscles of both legs was induced, and these phenomena increased wiggling and quick body sway.     

A novel multi-study intervention investigating the short and long term effects of a posture bra on whole body and breast kinematics

BackgroundPoor standing posture has been reported in women with larger breasts, increasing the risk of back pain. Whilst breast reduction surgery can improve posture, conservative measures such as special bras may offer short or long-term relief of symptoms without surgical intervention.Research questionThis study aimed to utilise a multi-study intervention to investigate the short and long-term kinematic effects of wearing a posture bra.MethodsStudy one utilised biomechanics and physiotherapy expertise to modify the design of a prototype bra to improve posture and breast kinematics; resulting in a second-generation posture bra. To test this bra, 24 females were randomly assigned to control and intervention groups. The control group wore their everyday bra; the intervention group wore the generation 2 posture bra in place of their everyday bra for three months. Pre and post intervention, posture (spine curvature, scapula position, whole body alignment) and breast kinematics were assessed during sitting, standing and walking. Short-term effects of the posture bra were compared to an everyday bra and no bra (study two), whilst the long-term effects were compared using the no bra condition (study three).ResultsBiomechanical intervention improved posture and breast kinematics in a prototype posture bra resulting in a second-generation prototype. Pre-intervention, the generation 2 posture bra significantly improved scapula retraction by 6° during both sitting and standing, but also increased deviation of whole body alignment compared to everyday bra and no bra conditions. During walking the posture bra reduced breast motion by 17 % compared to the everyday bra. Following the three-month wearer intervention, scapula depression significantly improved in the intervention group.SignificanceA biomechanically informed posture bra was able to effectively support the breasts and improve scapula position without compromising spinal curvature, reducing the risk of musculoskeletal pain associated with poor posture.     

Postural control adaptation to optic flow in children and adults with autism spectrum disorder

BackgroundSensory reweighting is important for humans to flexibly up-weigh and down-weigh sensory information in dynamic environments. There is an element of time involved in the sensory reweighting process. A longer time spent on sensory reweighting may increase the destabilizing effect of postural control. Individuals with autism spectrum disorder (ASD) are reported to have poor postural control. It is uncertain if a different sensory reweighting process underlies the postural control deficit in children and adults with ASD.Research questionTo explore the sensory reweighting capability in ASD, the present study examined whether the temporal domains of postural control differed in children and adults, with and without ASD under various optic flow conditions.MethodsThirty-three children (8–12 years old) and 33 adults (18–50 years old) with and without ASD underwent quiet standing in six radial optic flow conditions. Each condition lasted for 60 s and was shown twice to all participants. For each optic flow condition, changes in postural response within-trial and between-trials were measured.ResultsUnder various optic flow illusions, both children with and without ASD took a longer time to restore their posture compared with adults with and without ASD. Nonetheless, all groups demonstrated comparable abilities to adjust their posture to one that is close to the baseline position after one exposure to the optic flow stimulation.SignificanceThe present study showed that the temporal domains of postural control under different optic flow conditions were similar between individuals with and without ASD from the same age group. The ability to down-weigh visual information efficiently comes with the developmental progression of the sensory reweighting system. These findings suggest that the sensory reweighting process does not elucidate the postural control deficits in individuals with ASD and thus alternative explanations to determine the underlying mechanism for postural instability are needed.     

Normative values for the foot posture index between right and left foot: A descriptive study

BackgroundThe foot posture index (FPI) is a commonly used method to quantify standing foot posture. No normative data have, however, been presented to establish the range of a normal difference and asymmetrical differences between FPI score in the right foot and in the left foot.PurposeThe purpose of the present study was to establish normative values for the difference between the FPI scores across the two feet.MethodsAmong 930 healthy adults, FPI score was quantified in both feet. Difference between the two feet was calculated as FPI score on the right foot minus the FPI score on the left foot. Based on a normal distribution of the differences, asymmetry was defined as values below or above one standard deviation (SD) from the mean. Severe asymmetry was below and above ±2 SD from the mean. Normal difference was defined as the range between ±1 SD.ResultsA reference range for normal difference in FPI score between left foot and right foot was ?2 to +2. Asymmetry scores ranged from ?2 to ?4 and +2 to +4, while severe asymmetry was <?4 and >4.ConclusionNormative values for the difference between FPI scores in right foot and left foot have been presented from a large sample of healthy adults. These normative values can be used to identify a normal difference or an asymmetrical difference in foot posture across feet in one individual.