Although gaze during adaptive gait involving obstacle crossing is typically directed two or more steps ahead, visual information of the swinging lower-limb and its relative position in the environment (termed visual exproprioception) is available in the lower visual field (lvf). This study determined exactly when lvf exproprioceptive information is utilised to control/update lead-limb swing trajectory during obstacle negotiation. 12 young participants negotiated an obstacle wearing smart-glass goggles which unpredictably occluded the lvf for certain periods during obstacle approach and crossing. Trials were also completed with lvf occluded for the entirety of the trial. When lvf was occluded throughout, foot-placement distance and toe-clearance became significantly increased; which is consistent with previous work that likewise used continuous lvf occlusion. Both variables were similarly affected by lvf occlusion from instant of penultimate-step contact, but both were unaffected when lvf was occluded from instant of final-step contact. These findings suggest that lvf (exproprioceptive) input is typically used in an online manner to control/update final foot-placement, and that without such control, uncertainty regarding foot placement causes toe-clearance to be increased. Also that lvf input is not normally exploited in an online manner to update toe-clearance during crossing: which is contrary to what previous research has suggested.

BackgroundTo assess the cross-sectional association between self-rated eyesight and physical activity behaviour in a large general population sample of older English adults.MethodsAnalyses of data from the English Longitudinal Study of Ageing. Participants provided information on self-rated eyesight (categorised as: excellent/very good/good/fair–poor) and their own physical activity levels (categorised as: inactive/moderate only at least 1/week, vigorous at least 1/week). Associations between self-rated eyesight and physical activity levels were examined using logistic regression.ResultsA total of 6634 participants (mean age 65.0±9.2 years) were included in the analyses. In adjusted logistic regression models, those with fair–poor and good eyesight were significantly more likely to be inactive than those who reported excellent eyesight (OR 2.07, 95% CI 1.58 to 2.72; OR 1.59, 1.27 to 1.99, respectively).ConclusionIn this sample of older English adults, those with self-rated fair–poor vision were over twice as likely to be physically inactive than those who reported having excellent vision. When consistent data have emerged, interventions to increase physical activity in those who have poor eyesight are needed.

ObjectiveAthletes anticipating sport competition regularly experience distinct emotional and physiological responses as a result of the expected psychosocial and physical stress. Specifically, cortisol, an indicator of hypothalamic-pituitary-adrenal axis activation, prepares the athlete for the psychological and physiological demands of competition. The objective of this meta-analysis is to analyse the magnitude of the anticipatory cortisol response in athletes preparing to participate in sport competition and to examine the influence of gender, level of competition and data collection time.DesignSystematic review with meta-analysis.Data sourcesFour electronic databases were searched to March 2017: PubMed, PsycINFO, SPORTDiscus and Scopus.Eligibility criteria for selecting studies(1) Athletes participating in real sport competition;(2) salivary cortisol concentration collected before competition in addition to baseline sample(s);(3) original research article published in English language.ResultsData from 25 studies provided 27 effect sizes. A significant anticipatory cortisol response of g=0.85, p<0.001 was identified. Males had a stronger trend for greater cortisol reactivity (g=1.07) than females (g=0.56, p=0.07). Females and athletes competing at international level did not demonstrate a significant anticipatory stress response. There were no significant differences between level of competition, type of sport or time of competition. Meta-regression indicated that the anticipatory cortisol response is greater when assessed closer to the start of competition (Q=6.85, p=0.009).Summary/conclusionThe anticipatory cortisol response before sport competition reflects moderate cortisol reactivity that prepares athletes optimally for the demands of sport competition via the influence on cognitive processes and attentional control. However, both female athletes and international competitors did not demonstrate a significant anticipatory cortisol response, possibly due to differences in appraisal of the stress of sport competition.

Pedestrians regularly engage with their mobile phone whilst walking. The current study investigated how mobile phone use affects where people look (visual search behaviour) and how they negotiate a floor based hazard placed along the walking path. Whilst wearing a mobile eye tracker and motion analysis sensors, participants walked up to and negotiated a surface height change whilst writing a text, reading a text, talking on the phone, or without a phone. Differences in gait and visual search behaviour were found when using a mobile phone compared to when not using a phone. Using a phone resulted in looking less frequently and for less time at the surface height change, which led to adaptations in gait by negotiating it in a manner consistent with adopting an increasingly cautious stepping strategy. When using a mobile phone, writing a text whilst walking resulted in the greatest adaptions in gait and visual search behaviour compared to reading a text and talking on a mobile phone. Findings indicate that mobile phone users were able to adapt their visual search behaviour and gait to incorporate mobile phone use in a safe manner when negotiating floor based obstacles.

BackgroundDescending kerbs during locomotion involves the regulation of appropriate foot placement before the kerb-edge and foot clearance over it. It also involves the modulation of gait output to ensure the body-mass is safely and smoothly lowered to the new level. Previous research has shown that vision is used in such adaptive gait tasks for feedforward planning, with vision from the lower visual field (lvf) used for online updating. The present study determined when lvf information is used to control/update locomotion when stepping from a kerb.Methodology/Principal Findings12 young adults stepped down a kerb during ongoing gait. Force sensitive resistors (attached to participants' feet) interfaced with an high-speed PDLC ‘smart glass’ sheet, allowed the lvf to be unpredictably occluded at either heel-contact of the penultimate or final step before the kerb-edge up to contact with the lower level. Analysis focussed on determining changes in foot placement distance before the kerb-edge, clearance over it, and in kinematic measures of the step down. Lvf occlusion from the instant of final step contact had no significant effect on any dependant variable (p>0.09). Occlusion of the lvf from the instant of penultimate step contact had a significant effect on foot clearance and on several kinematic measures, with findings consistent with participants becoming uncertain regarding relative horizontal location of the kerb-edge.Conclusion/SignificanceThese findings suggest concurrent feedback of the lower limb, kerb-edge, and/or floor area immediately in front/below the kerb is not used when stepping from a kerb during ongoing gait. Instead heel-clearance and pre-landing-kinematic parameters are determined/planned using lvf information acquired in the penultimate step during the approach to the kerb-edge, with information related to foot placement before the kerb-edge being the most salient.

The study assessed the ability of the central nervous system (CNS) to use echoic information from sensory substitution devices (SSDs) to rotate the shoulders and safely pass through apertures of different width. Ten visually normal participants performed this task with full vision, or blindfolded using an SSD to obtain information regarding the width of an aperture created by two parallel panels. Two SSDs were tested. Participants passed through apertures of +0, +18, +35 and +70 % of measured body width. Kinematic indices recorded movement time, shoulder rotation, average walking velocity across the trial, peak walking velocities before crossing, after crossing and throughout a whole trial. Analyses showed participants used SSD information to regulate shoulder rotation, with greater rotation associated with narrower apertures. Rotations made using an SSD were greater compared to vision, movement times were longer, average walking velocity lower and peak velocities before crossing, after crossing and throughout the whole trial were smaller, suggesting greater caution. Collisions sometimes occurred using an SSD but not using vision, indicating that substituted information did not always result in accurate shoulder rotation judgements. No differences were found between the two SSDs. The data suggest that spatial information, provided by sensory substitution, allows the relative position of aperture panels to be internally represented, enabling the CNS to modify shoulder rotation according to aperture width. Increased buffer space indicated by greater rotations (up to approximately 35 % for apertures of +18 % of body width) suggests that spatial representations are not as accurate as offered by full vision.

The results indicate important areas of rehabilitation to address in addition to orientation and mobility in those with RP, including work-related activities and goals involving good central vision. Both people with RP and those supporting them could benefit from help addressing difficulties with communication.

Use of single-vision distance spectacles led to improvements in landing control, consistent with individuals' being more certain regarding the precise height of the lower floor level. This enhanced control was attributed to having a view of the foot, step edge, and immediate floor area that was not blurred, magnified, or doubled and that did not suffer from image jump or peripheral distortions. These findings provide further evidence that use of single-vision distance lenses in everyday locomotion may be advantageous for elderly multifocal wearers who have a high risk of falling.