763 research outputs found
Examining the ability to track multiple moving targets as a function of postural stability: a comparison between team sports players and sedentary individuals
Background: The ability to track multiple objects plays a key role in team ball sports
actions. However, there is a lack of research focused on identifying multiple object
tracking (MOT) performance under rapid, dynamic and ecologically valid
conditions. Therefore, we aimed to assess the effects of manipulating postural
stability on MOT performance.
Methods: Nineteen team sports players (soccer, basketball, handball) and sixteen
sedentary individuals performed the MOT task under three levels of postural stability
(high, medium, and low). For the MOT task, participants had to track three out of
eight balls for 10 s, and the object speed was adjusted following a staircase procedure.
For postural stability manipulation, participants performed three identical protocols
(randomized order) of the MOT task while standing on an unstable platform, using
the training module of the Biodex Balance System SD at levels 12 (high-stability),
eight (medium-stability), and four (low-stability).
Results: We found that the ability to track moving targets is dependent on the
balance stability conditions (F2,66 = 8.7, p < 0.001, ηÂČ = 0.09), with the disturbance of
postural stability having a negative effect on MOT performance. Moreover, when
compared to sedentary individuals, team sports players showed better MOT scores
for the high-stability and the medium-stability conditions (corrected p-value = 0.008,
Cohenâs d = 0.96 and corrected p-value = 0.009, Cohenâs d = 0.94; respectively)
whereas no differences were observed for the more unstable conditions (lowstability)
between-groups.
Conclusions: The ability to track moving targets is sensitive to the level of postural
stability, with the disturbance of balance having a negative effect on MOT
performance. Our results suggest that expertise in team sports training is transferred
to non-specific sport domains, as shown by the better performance exhibited by team
sports players in comparison to sedentary individuals. This study provides novel
insights into the link between individualâs ability to track multiple moving objects
and postural control in team sports players and sedentary individuals
The shortâterm effects of wearing swimming goggles on corneal biomechanics
Funding for open access charge: Universidad de Granada/CBUA. The authors have no financial or proprietary interest in a product, method or material described herein. The article has not been presented in a meeting.Purpose This study aimed to assess the impact
of wearing swimming goggles (SG) on corneal
biomechanics.
Methods Corneal deformation response, central
corneal thickness (CCT), intraocular pressure (IOP)
and biomechanically corrected intraocular pressure
(bIOP) were measured with the Corvis system (Oculus
OptikgerÀte GmbH, Wetzlar, Germany) in thirtyone
healthy young adults while wearing a drilled
SG. All measurements were obtained before, at 30 s,
2 min, 3.5 min and 5 min of wearing SG, just after
SG removal and after 2 min of SG removal.
Results The corneal biomechanics is sensitive to
SG wear, observing lower corneal deformability
during SG use. Specifically, wearing SG caused an
increase in the time and length of the first applanation
and radius curvature at the highest concavity,
as well as a decrease and in the velocity of the first
applanation and time and deformation amplitude
of the second applanation (p < 0.001 in all cases).
After SG removal, corneal biomechanical parameters
showed a rebound-effect, obtaining a higher corneal
deformability in comparison with baseline reading
(p-corrected < 0.05 in all cases). Additionally, IOP and bIOP significantly increased while wearing SG
(p < 0.001 in both cases), whereas CCT remained stable
(p = 0.850).
Conclusions Wearing SG modifies the biomechanical
properties of the cornea, with reduced corneal
deformability during SG wear. The outcomes of this
study should be taken into consideration when making
clinical decisions in subjects at high risk of developing
corneal ectasias or glaucoma, as well as in the
post-surgical management of these ocular conditions.Universidad de Granada/CBU
Effects of water drinking on corneal biomechanics: The association with intraocular pressure changes
Purpose: We aimed to assess the impact of drinking water (500 and 1000 mL) on corneal biomechanics
and determine the level of association between changes in intraocular pressure and variations in the
different biomechanical properties of the cornea. Methods: A total of 39 healthy young adults ingested
either 1000 mL (n = 21) or 500 mL (n = 18) of tap water in 5 min. The CorVis ST system was used to assess
corneal biomechanics at baseline and at 15, 30, and 45 min after water ingestion. Results: Water drinking
induced statistically significant changes in the deformation amplitude (P < 0.001, ηÂČ = 0.166), highest
concavity time (P = 0.012, ηÂČ = 0.093), peak distance (P < 0.001, ηÂČ = 0.171), time and velocity of the first
applanation (P < 0.001, ηÂČ = 0.288 and P = 0.016, ηÂČ = 0.087, respectively), and time and velocity of the second
applanation (P = 0.030, ηÂČ = 0.074 and P = 0.001, ηÂČ = 0.132, respectively), being independent of the amount
of water ingested (P > 0.05 in all cases). There were significant associations between changes in intraocular
pressure and some parameters of corneal biomechanics. Conclusion: Small variations in wholeâbody
hydration status alter different biomechanical properties of the cornea, with these changes being associated
with intraocular pressure levels. These findings indicate that wholeâbody hydration status can be considered
for the diagnosis and management of different ocular conditions
Changes in accommodation and behavioural performance with a contact lens for myopia management: A comparison between a dual-focus and a single-vision soft contact lens
Introduction: Dual-focus
soft contact lenses for myopia management have demonstrated
to be an effective strategy to reduce myopia progression. However, this
optical design has been shown to alter visual quality and accommodative function.
The aim of this study was to examine the accommodative and behavioural performance
during the execution of a psychomotor vigilance task (PVT) while wearing
dual-focus
and single-vision
soft contact lenses.
Methods: The steady-state
accommodative response was recorded with the
WAM-5500
binocular open-field
autorefractor during the execution of a 10-min
PVT at 50 cm either with the dual-focus
(MiSight 1-day)
or single-vision
(Proclear
1-day)
soft contact lenses, using a sample of 23 healthy young adults. Each experimental
session was performed on two different days in a counterbalanced order.
Results: A greater lag of accommodation, variability of accommodation and reaction
time was found while wearing dual-focus
in comparison with single-vision
soft contact lenses (mean differences during the 10-min
PVT were 0.58 ± 0.81 D,
p < 0.001; 0.31 ± 0.17 D, p < 0.001 and 15.22 ± 20.93 ms, p = 0.002, respectively). Also,
a time-on-
task
effect was found for the variability of accommodation and reaction
time (p = 0.001 and p < 0.001, respectively), observing higher values over time.
However, the lag of accommodation did not change significantly as a function of
time-on-
task
(p = 0.33).
Conclusion: Dual-focus
soft contact lens wear influences the steady-state
accommodative
response and behavioural performance during the execution of a visual
vigilance task in the short-term.
Eye care practitioners should be aware of these effects
when prescribing these lenses for myopia management, and provide specific
recommendations according to the individual visual needs
Short-term effects of text-background color combinations on the dynamics of the accommodative response
The purpose of the present study was to assess the accommodative response and pupillary dynamics while reading passages with different text-background color combinations on an LCD screen. Twenty healthy young adults read fourteen 2-min passages designed with fourteen different color combinations between text and background, while the accommodative and pupil responses were continuously measured with a binocular open-field autorefractometer. Our results revealed that the text-background color combination modulates the accommodative and pupillary dynamics during a 2-minutes reading task. The blue-red combination induced a heightened accommodative response, whereas positive polarities were associated with more variability of the accommodative response and smaller pupil sizes. Participants reported lower perceived ratings of legibility for text-background color combination with lower luminance contrast (white-yellow). The manipulation of text-background color did not have a significant effect on reading speed. These results may have important applications in the design of digital visual interfaces.This research was supported by the Spanish Ministry of Science, Innovation and Universities, with support from European Regional Development Fund (ERDF), RTI2018-094738-B-I00 project
Effect of manipulating the vergence/accommodation and image size mismatches of the ±2D flipper test on the frequency and precision of accommodative facility
Purpose: The ±2.00 D accommodative facility test presents several limitations, in-
cluding the lack of objective information and inherent characteristics such as ver-
gence/accommodative conflict, change in apparent size of the image, subjective
criteria for judging blur and motor reaction time. By using free-space viewing con-
ditions and an open-field autorefractor to monitor the refractive state, we exam-
ined the impact of manipulating these factors on the qualitative and quantitative
assessment of accommodative facility.
Methods: Twenty-five healthy young adults (24.5 ± 4.5 years) took part in this
study. Participants performed three accommodative facility tests (adapted flipper,
4D free-space viewing and 2.5D free-space viewing) under both monocular and
binocular conditions in random order. A binocular open-field autorefractor was
used to assess the accommodative response continuously, and these data were
used to characterise accommodative facility quantitatively and qualitatively.
Results: There were statistically significant differences between the three testing
methods both quantitatively (p < 0.001) and qualitatively (p = 0.02). For the same
accommodative demand, a lower number of cycles was obtained for the adapted
flipper condition in comparison with the 4D free-space viewing test (corrected
p-value < 0.001, Cohen's d = 0.78). However, this comparison did not reach statisti-
cal significance for qualitative measures of accommodative facility (corrected p-
value = 0.82, Cohen's d 0.05).
Conclusions: These data provide evidence that the qualitative assessment of ac-
commodative facility is not influenced by the inherent limitations of the ±2.00 D
flipper test. The use of qualitative outcomes by incorporating an open-field au-
torefractor allows examiners to increase the validity of the accommodative facility
test in both clinical and research settings
Intraocular pressure responses to a virtual reality shooting simulation in active-duty members of the Spanish Army: The influence of task complexity
Ocular physiology is sensitive to cognitively demanding tasks. However, it is unknown whether the intraocular
pressure is also affected by the cognitive demands of military operations. The main objective was to determine
the impact of a virtual reality shooting simulation with two levels of complexity on intraocular pressure levels in
military personnel. Eighteen active-duty members of the Spanish Army and eighteen civilians performed two 4
min simulated shooting tasks with two levels of complexity using a virtual reality. In the âeasyâ task participants
performed a simulated shoot when the stimulus (military with a rifle) appeared, while in the âdifficultâ task the
stimulus randomly was a military with a rifle or with his hands on the air and participants were instructed to
respond only when the military with a rifle appeared. Intraocular pressure was measured with a rebound
tonometer before and immediately after each task. Complementarily, perceived levels of mental load and
shooting performance (reaction time) were assessed. Intraocular pressure was greater after completing the more
complex task in both military personnel (p-value < 0.01, CohenÂŽs d = 1.19) and civilians (p-value < 0.01, CohenÂŽs
d = 1.16). Also, perceived levels of task load and reaction time were higher in the difficult compared to the easy
shooting tasks (both p < 0.001). The rise in intraocular pressure is positively associated with the cognitive
demands of simulated military operations. The potential application of this finding is the development of
objective tools based on intraocular pressure for the evaluation of the mental state in real-world contexts,
permitting to improve soldiersÂŽsafety and performance.CEMIX (Centro Mixto UGR-MADOC, Army of Spain) 5/4/20 TR-COMBAT
Association of military-specific reaction time performance with physical fitness and visual skills
Background: The aim of the present study was to explore whether military-specific
reaction time (RT) test performance is affected by individualsâ physical and visual
skills.
Method: In a single testing session, the military-specific Simple and Go, No-Go RT,
aerobic power (20-m Multistage Shuttle Run test), maximal upper- and lower-body
mechanical capacities (bench press and squat against different loads), and visual
skills (multiple object tracking and dynamic visual acuity) of 30 young men (15
active-duty military personnel and 15 sport science students) were evaluated.
Results: The main findings revealed that the Simple RT and Go, No-Go RT presented
(1) with aerobic power non-significant small correlations in military personnel
(r = â0.39 and â0.35, respectively) and non-significant negligible correlations in
sport science students (r = â0.10 and 0.06, respectively), (2) inconsistent and
generally non-significant correlations with the maximal mechanical capacities of the
upper- and lower-body muscles (r range = â0.10, 0.67 and â0.27, 0.48, respectively),
(3) non-significant correlations with visual skills (r magnitude â„ 0.58) with the only
exception of the Go, No-Go RT that was significantly correlated to all visual variables
in the group of students (i.e., students who achieved better results during visual tests
had shorter RT; r magnitude â„ 0.58), and (4) none of the physical and visual variables
significantly predicted the Simple RT or Go, No-Go RT.
Conclusion: Altogether, these results indicate that military-specific RT performance
is generally independent of physical and visual skills in both military personnel and
active university students.CEMIX (Centro Mixto UGR-MADOC, Army of Spain) 5/4/20 TR-COMBATEMinistry of Education, Science & Technological Development, Serbia 451-03-9/2021-14/20015
Repositioning of the global epicentre of non-optimal cholesterol
High blood cholesterol is typically considered a feature of wealthy western countries(1,2). However, dietary and behavioural determinants of blood cholesterol are changing rapidly throughout the world(3) and countries are using lipid-lowering medications at varying rates. These changes can have distinct effects on the levels of high-density lipoprotein (HDL) cholesterol and non-HDL cholesterol, which have different effects on human health(4,5). However, the trends of HDL and non-HDL cholesterol levels over time have not been previously reported in a global analysis. Here we pooled 1,127 population-based studies that measured blood lipids in 102.6 million individuals aged 18 years and older to estimate trends from 1980 to 2018 in mean total, non-HDL and HDL cholesterol levels for 200 countries. Globally, there was little change in total or non-HDL cholesterol from 1980 to 2018. This was a net effect of increases in low- and middle-income countries, especially in east and southeast Asia, and decreases in high-income western countries, especially those in northwestern Europe, and in central and eastern Europe. As a result, countries with the highest level of non-HDL cholesterol-which is a marker of cardiovascular riskchanged from those in western Europe such as Belgium, Finland, Greenland, Iceland, Norway, Sweden, Switzerland and Malta in 1980 to those in Asia and the Pacific, such as Tokelau, Malaysia, The Philippines and Thailand. In 2017, high non-HDL cholesterol was responsible for an estimated 3.9 million (95% credible interval 3.7 million-4.2 million) worldwide deaths, half of which occurred in east, southeast and south Asia. The global repositioning of lipid-related risk, with non-optimal cholesterol shifting from a distinct feature of high-income countries in northwestern Europe, north America and Australasia to one that affects countries in east and southeast Asia and Oceania should motivate the use of population-based policies and personal interventions to improve nutrition and enhance access to treatment throughout the world.Peer reviewe
Height and body-mass index trajectories of school-aged children and adolescents from 1985 to 2019 in 200 countries and territories: a pooled analysis of 2181 population-based studies with 65 million participants
Summary Background Comparable global data on health and nutrition of school-aged children and adolescents are scarce. We aimed to estimate age trajectories and time trends in mean height and mean body-mass index (BMI), which measures weight gain beyond what is expected from height gain, for school-aged children and adolescents. Methods For this pooled analysis, we used a database of cardiometabolic risk factors collated by the Non-Communicable Disease Risk Factor Collaboration. We applied a Bayesian hierarchical model to estimate trends from 1985 to 2019 in mean height and mean BMI in 1-year age groups for ages 5â19 years. The model allowed for non-linear changes over time in mean height and mean BMI and for non-linear changes with age of children and adolescents, including periods of rapid growth during adolescence. Findings We pooled data from 2181 population-based studies, with measurements of height and weight in 65 million participants in 200 countries and territories. In 2019, we estimated a difference of 20 cm or higher in mean height of 19-year-old adolescents between countries with the tallest populations (the Netherlands, Montenegro, Estonia, and Bosnia and Herzegovina for boys; and the Netherlands, Montenegro, Denmark, and Iceland for girls) and those with the shortest populations (Timor-Leste, Laos, Solomon Islands, and Papua New Guinea for boys; and Guatemala, Bangladesh, Nepal, and Timor-Leste for girls). In the same year, the difference between the highest mean BMI (in Pacific island countries, Kuwait, Bahrain, The Bahamas, Chile, the USA, and New Zealand for both boys and girls and in South Africa for girls) and lowest mean BMI (in India, Bangladesh, Timor-Leste, Ethiopia, and Chad for boys and girls; and in Japan and Romania for girls) was approximately 9â10 kg/m2. In some countries, children aged 5 years started with healthier height or BMI than the global median and, in some cases, as healthy as the best performing countries, but they became progressively less healthy compared with their comparators as they grew older by not growing as tall (eg, boys in Austria and Barbados, and girls in Belgium and Puerto Rico) or gaining too much weight for their height (eg, girls and boys in Kuwait, Bahrain, Fiji, Jamaica, and Mexico; and girls in South Africa and New Zealand). In other countries, growing children overtook the height of their comparators (eg, Latvia, Czech Republic, Morocco, and Iran) or curbed their weight gain (eg, Italy, France, and Croatia) in late childhood and adolescence. When changes in both height and BMI were considered, girls in South Korea, Vietnam, Saudi Arabia, Turkey, and some central Asian countries (eg, Armenia and Azerbaijan), and boys in central and western Europe (eg, Portugal, Denmark, Poland, and Montenegro) had the healthiest changes in anthropometric status over the past 3·5 decades because, compared with children and adolescents in other countries, they had a much larger gain in height than they did in BMI. The unhealthiest changesâgaining too little height, too much weight for their height compared with children in other countries, or bothâoccurred in many countries in sub-Saharan Africa, New Zealand, and the USA for boys and girls; in Malaysia and some Pacific island nations for boys; and in Mexico for girls. Interpretation The height and BMI trajectories over age and time of school-aged children and adolescents are highly variable across countries, which indicates heterogeneous nutritional quality and lifelong health advantages and risks
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