Displaying publications 121 - 140 of 4601 in total

Abstract:
Sort:
  1. The effects of toe-out and toe-in postures on static & dynamic balance, risk of fall and TUG score in healthy adults
    Khan SJ, Khan SS, Usman J
    Foot (Edinb), 2019 Jun;39:122-128.
    PMID: 30580888 DOI: 10.1016/j.foot.2018.06.002
    BACKGROUND: Toe-in and toe-out foot positions have not yet been tested for dynamic balance and risk of fall. The aim of this study was to investigate the effects of these two modifications on static and dynamic postural stability and risk of fall through instrumental (Biodex Balance System®) and functional (timed up and go-TUG test) tools.

    METHODOLOGY: Twenty healthy adults (8 males, 12 females, age: 29±4.10years, BMI: 21.56±2.36kg/m2) participated in this study. Static and dynamic (levels 8 and 2) balance with single stance and double stance and dynamic (level 8 and levels 6-2) for risk of fall with double stance were tested with the Biodex Balance System with three self-selected feet positions: straight (13.8°), toe-out (35.6°) and toe-in (-11.9°) for each test condition. Additionally, TUG test was performed with toe-out and toe-in gait.

    RESULTS: The results of repeated measures ANOVA showed significant differences (p<0.05) between straight and modified toe angles in balance at dynamic level 2 with both double and single stance conditions. Significant differences (p<0.001) were also found in TUG scores for the test conditions.

    CONCLUSION: Toe-in and toe-out gait modifications have significant effects on balance at higher levels of platform tilt and functional balance. Further investigations with knee osteoarthritis patients and electromyography may provide insight in balancing strategies adopted by the body in toe-out and toe-in gait.

    Matched MeSH terms: Postural Balance/physiology*; Motor Activity/physiology; Posture/physiology*; Toes/physiology*
  2. The effects of moisture on ovipositional responses and larval eclosion of Aedes albopictus
    Saifur RG, Dieng H, Hassan AA, Satho T, Miake F, Boots M, et al.
    J Am Mosq Control Assoc, 2010 Dec;26(4):373-80.
    PMID: 21290932
    Moisture plays a major role in the dynamics of mosquito populations, especially those breeding in container habitats. Despite this importance, the role of moisture conditions as they affect oviposition and egg development in Aedes vectors remains largely unexplored. We investigated the effect of exposing gravid female Aedes albopictus mosquitoes and their eggs to different moisture levels (MLs) for various periods on oviposition and hatching. Overall, high-moisture substrates (HMSs; 66% and 72%) provided better environments for egg laying. The timing of initial egg laying was far longer at the lowest substrate moisture level (LSML, 25% and 41.2%) than at HMSs. The numbers of eggs laid were much lower in the drier environments. At LSMLs, gravid females retained increasing numbers of mature eggs until death, and egg retention decreased gradually with increasing ML. The HMSs also provided better environments for larval eclosion. The numbers of eggs hatched were lower at the LSML than the HSML environment. No egg hatching occurred after 1 h exposure to moisture. However, egg hatching occurred by installment, with spontaneous hatching (SH) increasing gradually with increasing ML. High-moisture conditions combined with long exposure (30 h and 48 h) favored SH. These results suggest that Ae. albopictus females can respond to better moisture conditions for increased success of embryonation and larval eclosion. This information may be useful in the colonization of floodwater Aedes species.
    Matched MeSH terms: Aedes/physiology*; Larva/physiology; Oviposition/physiology*; Ovum/physiology
  3. Introduction to the Cognitive Abilities Account for the Reminiscence Bump in the Temporal Distribution of Autobiographical Memory
    Janssen SMJ
    Psychol Rep, 2020 Feb;123(1):12-42.
    PMID: 31039675 DOI: 10.1177/0033294119843221
    Matched MeSH terms: Aging/physiology*; Aptitude/physiology*; Cognition/physiology*; Mental Recall/physiology*
  4. Fulltext Cryptic coloration of Macaranga bancana seedlings: A unique strategy for a pioneer species
    Fadzly N, Zuharah WF, Mansor A, Zakaria R
    Plant Signal Behav, 2016 07 02;11(7):e1197466.
    PMID: 27315145 DOI: 10.1080/15592324.2016.1197466
    Macaranga bancana is considered as a successful pioneer plant species. Usually found in disturbed and open areas, most of the current research focused on its relations with ants. One of the unique feature of the plants is that the seedling leaves are red, resembling and almost matching the background. Using a portable spectrometer, we measured the color reflectance of M. bancana seedlings (less than 20 cm in height). We also measured the leaf litter reflectance, adult M. bancana leaves and also seedlings of several other species found in the vicinity of M. bancana seedlings. The reflectances of M. bancana seedlings are very similar to that of the leaf litter background. We suggest that this cryptic coloration is crucial during the early stages of the plant when it still cannot rely on the protection of ants.
    Matched MeSH terms: Pigmentation/physiology; Plant Leaves/physiology; Euphorbiaceae/physiology; Seedlings/physiology
  5. Fulltext Pollination Services of Mango Flower Pollinators
    Huda AN, Salmah MR, Hassan AA, Hamdan A, Razak MN
    J Insect Sci, 2015;15.
    PMID: 26246439 DOI: 10.1093/jisesa/iev090
    Measuring wild pollinator services in agricultural production is very important in the context of sustainable management. In this study, we estimated the contribution of native pollinators to mango fruit set production of two mango cultivars Mangifera indica (L). cv. 'Sala' and 'Chok Anan'. Visitation rates of pollinators on mango flowers and number of pollen grains adhering to their bodies determined pollinator efficiency for reproductive success of the crop. Chok Anan failed to produce any fruit set in the absence of pollinators. In natural condition, we found that Sala produced 4.8% fruit set per hermaphrodite flower while Chok Anan produced 3.1% per flower. Hand pollination tremendously increased fruit set of naturally pollinated flower for Sala (>100%), but only 33% for Chok Anan. Pollinator contribution to mango fruit set was estimated at 53% of total fruit set production. Our results highlighted the importance of insect pollinations in mango production. Large size flies Eristalinus spp. and Chrysomya spp. were found to be effective pollen carriers and visited more mango flowers compared with other flower visitors.
    Matched MeSH terms: Diptera/physiology; Insects/physiology*; Mangifera/physiology*; Flowers/physiology
  6. Diet and internal physiological changes of female orange mud crabs, Scylla olivacea (Herbst, 1796) in different ovarian maturation stages
    Hidir A, Aaqillah-Amr MA, Noordiyana MN, Ikhwanuddin M
    Anim. Reprod. Sci., 2018 Aug;195:216-229.
    PMID: 29861342 DOI: 10.1016/j.anireprosci.2018.05.026
    Recently, there has been a growing interest in the ovarian maturation of mud crabs, genus Scylla. Studies regarding the factors that affect ovarian maturation in mud crabs, however, are still lacking. This study, therefore, evaluates the relationship between diet and internal physiological changes of female orange mud crabs, Scylla olivacea. Sixty female adult S. olivacea were sampled from Setiu Wetland, Malaysia. Foreguts were sampled to study fullness and content. The hepatopancreas was sampled to study digestive enzyme activity, biochemical composition, and histology. Ovaries were sampled to study ovarian biochemical composition and histology. Foregut fullness data suggest that there is an increase in feeding with advancing ovarian maturation in mud crabs. Data for foregut contents indicated that when the ovary was in Stage 3 of maturation the diet was animal-based. The activity of amylase, cellulase, lipase, and trypsin during Stages 1 and 4 of ovarian maturation were less than during Stage 3 of ovarian maturation. Biochemical composition (protein and lipid) was greater during Stage 3 of ovarian maturation. Histological analysis of the hepatopancreas indicated an increase in hepatopancreas tubules, B and R cells during Stage 3 as compared with Stage 1 of ovarian maturation. Histological analysis of the ovary indicated increases in oocyte diameter due to concentrated large yolk globules. Based on these results, it is concluded that vitellogenesis mainly occurred during Stage 3 of ovarian maturation, based on evidence of increased feeding with the diet being predominantly animal-based. Likewise, digestive enzyme activities, proteins, lipids, B cells, and R cells were all greater during Stage 3 of ovarian maturation.
    Matched MeSH terms: Brachyura/physiology*; Feeding Behavior/physiology*; Ovary/physiology*; Gastrointestinal Tract/physiology
  7. Review of numerical methods for simulation of mechanical heart valves and the potential for blood clotting
    Zakaria MS, Ismail F, Tamagawa M, Aziz AFA, Wiriadidjaja S, Basri AA, et al.
    Med Biol Eng Comput, 2017 Sep;55(9):1519-1548.
    PMID: 28744828 DOI: 10.1007/s11517-017-1688-9
    Even though the mechanical heart valve (MHV) has been used routinely in clinical practice for over 60 years, the occurrence of serious complications such as blood clotting remains to be elucidated. This paper reviews the progress that has been made over the years in terms of numerical simulation method and the contribution of abnormal flow toward blood clotting from MHVs in the aortic position. It is believed that this review would likely be of interest to some readers in various disciplines, such as engineers, scientists, mathematicians and surgeons, to understand the phenomenon of blood clotting in MHVs through computational fluid dynamics.
    Matched MeSH terms: Blood Coagulation/physiology*; Blood Flow Velocity/physiology; Heart Valves/physiology*; Pulsatile Flow/physiology
  8. A systematic review of muscle activity assessment of the biceps brachii muscle using mechanomyography
    Talib I, Sundaraj K, Lam CK, Sundaraj S
    J Musculoskelet Neuronal Interact, 2018 12 01;18(4):446-462.
    PMID: 30511949
    This systematic review aims to categorically analyses the literature on the assessment of biceps brachii (BB) muscle activity through mechanomyography (MMG). The application of our search criteria to five different databases identified 319 studies. A critical review of the 48 finally selected records, revealed the diversity of protocols and parameters that are employed in MMG-based assessments of BB muscle activity. The observations were categorized into the following: muscle torque, fatigue, strength and physiology. The available information on the muscle contraction protocol, sensor(s), MMG signal parameters and obtained results were then tabulated based on these categories for further analysis. The review affirms that - 1) MMG is suitable for skeletal muscle activity assessment and can be employed potentially for further investigation of the BB muscle activity and condition (e.g., force, torque, fatigue, and contractile properties), 2) a majority of the records focused on static contractions of the BB, and the analysis of dynamic muscle contractions using MMG is thus a research gap, and 3) very few studies have focused on the analysis of BB muscle activity under externally stimulated contractions. Taken together, the findings of this review on BB activity assessment using MMG affirm the potential of MMG as an alternative tool.
    Matched MeSH terms: Biomechanical Phenomena/physiology; Muscle Contraction/physiology*; Muscle, Skeletal/physiology*; Muscle Fatigue/physiology*
  9. Fulltext Gliding saves time but not energy in Malayan colugos
    Byrnes G, Libby T, Lim NT, Spence AJ
    J Exp Biol, 2011 Aug 15;214(Pt 16):2690-6.
    PMID: 21795564 DOI: 10.1242/jeb.052993
    Gliding is thought to be an economical form of locomotion. However, few data on the climbing and gliding of free-ranging gliding mammals are available. This study employed an animal-borne three-dimensional acceleration data-logging system to collect continuous data on the climbing and gliding of free-ranging Malayan colugos, Galeopterus variegatus. We combined these movement data with empirical estimates of the metabolic costs to move horizontally or vertically to test this long-standing hypothesis by determining whether the metabolic cost to climb to sufficient height to glide a given distance was less than the cost to move an equivalent distance horizontally through the canopy. On average, colugos climb a short distance to initiate glides. However, due to the high energetic cost of climbing, gliding is more energetically costly to move a given horizontal distance than would be predicted for an animal travelling the same distance through the canopy. Furthermore, because colugos spend a small fraction of their time engaged in locomotor activity, the high costs have little effect on their overall energy budget. As a result, the energetic economy hypothesis for the origins of gliding is not supported. It is likely that other ecologically relevant factors have played a greater role in the origins of gliding in colugos and other mammals.
    Matched MeSH terms: Energy Metabolism/physiology*; Flight, Animal/physiology*; Lemur/physiology*; Locomotion/physiology
  10. Fulltext In vivo bone strain and finite element modeling of a rhesus macaque mandible during mastication
    Panagiotopoulou O, Iriarte-Diaz J, Wilshin S, Dechow PC, Taylor AB, Mehari Abraha H, et al.
    Zoology (Jena), 2017 10;124:13-29.
    PMID: 29037463 DOI: 10.1016/j.zool.2017.08.010
    Finite element analysis (FEA) is a commonly used tool in musculoskeletal biomechanics and vertebrate paleontology. The accuracy and precision of finite element models (FEMs) are reliant on accurate data on bone geometry, muscle forces, boundary conditions and tissue material properties. Simplified modeling assumptions, due to lack of in vivo experimental data on material properties and muscle activation patterns, may introduce analytical errors in analyses where quantitative accuracy is critical for obtaining rigorous results. A subject-specific FEM of a rhesus macaque mandible was constructed, loaded and validated using in vivo data from the same animal. In developing the model, we assessed the impact on model behavior of variation in (i) material properties of the mandibular trabecular bone tissue and teeth; (ii) constraints at the temporomandibular joint and bite point; and (iii) the timing of the muscle activity used to estimate the external forces acting on the model. The best match between the FEA simulation and the in vivo experimental data resulted from modeling the trabecular tissue with an isotropic and homogeneous Young's modulus and Poisson's value of 10GPa and 0.3, respectively; constraining translations along X,Y, Z axes in the chewing (left) side temporomandibular joint, the premolars and the m1; constraining the balancing (right) side temporomandibular joint in the anterior-posterior and superior-inferior axes, and using the muscle force estimated at time of maximum strain magnitude in the lower lateral gauge. The relative strain magnitudes in this model were similar to those recorded in vivo for all strain locations. More detailed analyses of mandibular strain patterns during the power stroke at different times in the chewing cycle are needed.
    Matched MeSH terms: Bone and Bones/physiology*; Macaca mulatta/physiology*; Mandible/physiology*; Mastication/physiology*
  11. The limits of stability and muscle activity in middle-aged adults during static and dynamic stance
    Ku PX, Abu Osman NA, Wan Abas WAB
    J Biomech, 2016 Dec 08;49(16):3943-3948.
    PMID: 27865478 DOI: 10.1016/j.jbiomech.2016.11.006
    Balance control plays an important role in maintaining daily activity. However, studies on postural control among middle-aged adults are scarce. This study aims (i) to examine directional control (DCL) and electromyography activity (EMG) for different stability levels, and (ii) to determine left-right asymmetry for DCL and muscle activity among sedentary middle-aged adults. Twenty healthy, middle-aged adults (10 males, 10 females; age=50.0±7.5yrs; body height: 1.61±0.10m; body mass: 70.0±14.5kg) participated in the study. EMG for left and right side of rectus femoris (RF), biceps femoris (BF), and medial gastrocnemius (MG) were recorded. Two-way repeated measures analysis of variance was used to assess the effect of dynamic level on DCL and EMG, whereas independent sample t-test was conducted to analyse the asymmetries of DCL and EMG for the left and right leg. When the dynamic tilt surface increased, DCL scores significantly decreased (except forward, forward-rightward, and backward-leftward direction) and only RF muscle indicated significant differences. Left-right asymmetry was found in BF and MG muscles. No significant gender difference was observed in DCL and EMG. These data demonstrated that increased dynamic tilt surface may increase the displacement of center of pressure of certain directions, and stimulate RF activity in dynamic stance among sedentary middle-aged adults. Further studies should be conducted to examine the dynamic stance and muscle activity of the lower limb in age-matched patient groups with balance abnormalities.
    Matched MeSH terms: Postural Balance/physiology; Leg/physiology; Posture/physiology*; Muscle, Skeletal/physiology*
  12. Newborns are sensitive to the correspondence between auditory pitch and visuospatial elevation
    Walker P, Bremner JG, Lunghi M, Dolscheid S, D Barba B, Simion F
    Dev Psychobiol, 2018 03;60(2):216-223.
    PMID: 29355921 DOI: 10.1002/dev.21603
    Amodal (redundant) and arbitrary cross-sensory feature associations involve the context-insensitive mapping of absolute feature values across sensory domains. Cross-sensory associations of a different kind, known as correspondences, involve the context-sensitive mapping of relative feature values. Are such correspondences in place at birth (like amodal associations), or are they learned from subsequently experiencing relevant feature co-occurrences in the world (like arbitrary associations)? To decide between these two possibilities, human newborns (median age = 44 hr) watched animations in which two balls alternately rose and fell together in space. The pitch of an accompanying sound rose and fell either congruently with this visual change (pitch rising and falling as the balls moved up and down), or incongruently (pitch rising and falling as the balls moved down and up). Newborns' looking behavior was sensitive to this congruence, providing the strongest indication to date that cross-sensory correspondences can be in place at birth.
    Matched MeSH terms: Child Development/physiology*; Motion Perception/physiology*; Pattern Recognition, Visual/physiology*; Pitch Perception/physiology*
  13. Sensory adaptation and inhibition of return: dissociating multiple inhibitory cueing effects
    Lim A, Eng V, Janssen SMJ, Satel J
    Exp Brain Res, 2018 05;236(5):1369-1382.
    PMID: 29520444 DOI: 10.1007/s00221-018-5225-3
    Inhibition of return (IOR) refers to an increase in reaction times to targets that appeared at a previously cued location relative to an uncued location, often investigated using a spatial cueing paradigm. Despite numerous studies that have examined many aspects of IOR, the neurophysiological mechanisms underlying IOR are still in dispute. The objective of the current research is to investigate the plausible mechanisms by manipulating the cue and target types between central and peripheral stimuli in a traditional cue-target paradigm with saccadic responses to targets. In peripheral-cueing conditions, we observed inhibitory cueing effects across all cue-target onset asynchronies (CTOAs) with peripheral targets, but IOR was smaller and arose later with central targets. No inhibition was observed in central-cueing conditions at any CTOAs. Empirical data were simulated using a two-dimensional dynamic neural field model. Our results and simulations support previous work demonstrating that, at short CTOAs, behavioral inhibition is only observed with repeated stimulation-an effect of sensory adaptation. With longer CTOAs, IOR is observed regardless of target type when peripheral cueing is used. Our findings suggest that behaviorally exhibited inhibitory cueing effects can be attributed to multiple mechanisms, including both attenuation of visual stimulation and local inhibition in the superior colliculus.
    Matched MeSH terms: Adaptation, Physiological/physiology*; Attention/physiology*; Reaction Time/physiology*; Saccades/physiology
  14. The reproducibility of physiological responses and performance profiles of youth soccer players in small-sided games
    Hill-Haas S, Rowsell G, Coutts A, Dawson B
    Int J Sports Physiol Perform, 2008 Sep;3(3):393-6.
    PMID: 19211950
    Matched MeSH terms: Competitive Behavior/physiology; Physical Fitness/physiology*; Soccer/physiology*; Athletic Performance/physiology*
  15. Effects of rainfall exclusion on leaf gas exchange traits and osmotic adjustment in mature canopy trees of Dryobalanops aromatica (Dipterocarpaceae) in a Malaysian tropical rain forest
    Inoue Y, Ichie T, Kenzo T, Yoneyama A, Kumagai T, Nakashizuka T
    Tree Physiol, 2017 10 01;37(10):1301-1311.
    PMID: 28541561 DOI: 10.1093/treephys/tpx053
    Climate change exposes vegetation to unusual levels of drought, risking a decline in productivity and an increase in mortality. It still remains unclear how trees and forests respond to such unusual drought, particularly Southeast Asian tropical rain forests. To understand leaf ecophysiological responses of tropical rain forest trees to soil drying, a rainfall exclusion experiment was conducted on mature canopy trees of Dryobalanops aromatica Gaertn.f. (Dipterocarpaceae) for 4 months in an aseasonal tropical rain forest in Sarawak, Malaysia. The rainfall was intercepted by using a soft vinyl chloride sheet. We compared the three control and three treatment trees with respect to leaf water use at the top of the crown, including stomatal conductance (gsmax), photosynthesis (Amax), leaf water potential (predawn: Ψpre; midday: Ψmid), leaf water potential at turgor loss point (πtlp), osmotic potential at full turgor (π100) and a bulk modulus of elasticity (ε). Measurements were taken using tree-tower and canopy-crane systems. During the experiment, the treatment trees suffered drought stress without evidence of canopy dieback in comparison with the control trees; e.g., Ψpre and Ψmid decreased with soil drying. Minimum values of Ψmid in the treatment trees decreased during the experiment, and were lower than πtlp in the control trees. However, the treatment trees also decreased their πtlp by osmotic adjustment, and the values were lower than the minimum values of their Ψmid. In addition, the treatment trees maintained gs and Amax especially in the morning, though at midday, values decreased to half those of the control trees. Decreasing leaf water potential by osmotic adjustment to maintain gs and Amax under soil drying in treatment trees was considered to represent anisohydric behavior. These results suggest that D. aromatica may have high leaf adaptability to drought by regulating leaf water consumption and maintaining turgor pressure to improve its leaf water relations.
    Matched MeSH terms: Trees/physiology*; Water/physiology*; Plant Leaves/physiology*; Dipterocarpaceae/physiology*
  16. Patchy stomatal behavior in broad-leaved trees grown in different habitats
    Takanashi S, Kosugi Y, Matsuo N, Tani M, Ohte N
    Tree Physiol, 2006 Dec;26(12):1565-78.
    PMID: 17169896
    Effects of heterogeneity in stomatal behavior on gas-exchange characteristics of leaves from four tree species growing in different climates, including temperate, tropical monsoon and tropical rain forest, were investigated by combining gas-exchange measurements and the pressure-infiltration method. Field observations indicated linear relationships between whole-leaf conductance and the ratio of infiltrated to non-infiltrated leaf area (open stomata area) in Dipterocarpus sublamellatus Foxw. and Neobalanocarpus heimii (King) Ashton in a tropical rain forest in Peninsular Malaysia, whereas the ratio of infiltrated to non-infiltrated area rapidly increased up to the whole-leaf conductance at which the entire leaf was infiltrated in Cinnamomum camphora Sieb. in a temperate evergreen forest in Japan and in Azadirachta indica Juss. in a tropical monsoon area in Thailand. These results strongly suggest small ranges in bell-shaped stomatal conductance distributions in C. camphora and A. indica and bimodal stomatal conductance distributions in D. sublamellatus and N. heimii. The values of normalized maximum carboxylation rate at 25 degrees C (V(cmax25)) derived from gas-exchange measurements were not constant, but decreased with decreasing whole-leaf conductance in D. sublamellatus and N. heimii. A gas-exchange model analysis revealed a linear relationship between whole-leaf conductance and the ratio of infiltrated to non-infiltrated leaf area for bimodal stomatal conductance distributions, whereas for bell-shaped distributions, the relationships were nonlinear. Midday depression of apparent V(cmax25) in these species was mainly caused by bimodal stomatal closure. The bimodal stomatal distribution model could also explain diurnal changes in photosynthetic assimilation and transpiration rates in these species.
    Matched MeSH terms: Photosynthesis/physiology*; Trees/physiology*; Plant Leaves/physiology*; Angiosperms/physiology*
  17. Interspecific variation of photosynthesis and leaf characteristics in canopy trees of five species of Dipterocarpaceae in a tropical rain forest
    Kenzo T, Ichie T, Yoneda R, Kitahashi Y, Watanabe Y, Ninomiya I, et al.
    Tree Physiol, 2004 Oct;24(10):1187-92.
    PMID: 15294766
    Photosynthetic rate, nitrogen concentration and morphological properties of canopy leaves were studied in 18 trees, comprising five dipterocarp species, in a tropical rain forest in Sarawak, Malaysia. Photosynthetic rate at light saturation (Pmax) differed significantly across species, varying from 7 to 18 micro mol m(-2) s(-1). Leaf nitrogen concentration and morphological properties, such as leaf blade and palisade layer thickness, leaf mass per area (LMA) and surface area of mesophyll cells per unit leaf area (Ames/A), also varied significantly across species. Among the relationships with leaf characteristics, Pmax had the strongest correlation with leaf mesophyll parameters, such as palisade cell layer thickness (r2 = 0.76, P < 0.001) and Ames/A (r2 = 0.73, P < 0.001). Leaf nitrogen concentration and Pmax per unit area also had a significant but weaker correlation (r2 = 0.46, P < 0.01), whereas Pmax had no correlation, or only weakly significant correlations, with leaf blade thickness and LMA. Shorea beccariana Burck, which had the highest P(max) of the species studied, also had the thickest palisade layer, with up to five or more layers. We conclude that interspecific variation in photosynthetic capacity in tropical rain forest canopies is influenced more by leaf mesophyll structure than by leaf thickness, LMA or leaf nitrogen concentration.
    Matched MeSH terms: Photosynthesis/physiology*; Trees/physiology*; Plant Leaves/physiology*; Theales/physiology*
  18. Central effects of mouth rinses on endurance and strength performance
    Tan SH, Khong TK, Selvanayagam VS, Yusof A
    Eur J Appl Physiol, 2024 Feb;124(2):403-415.
    PMID: 38038740 DOI: 10.1007/s00421-023-05350-w
    Rinsing the mouth with a carbohydrate (CHO) solution has been shown to enhance exercise performance while reducing neuromuscular fatigue. This effect is thought to be mediated through the stimulation of oral receptors, which activate brain areas associated with reward, motivation, and motor control. Consequently, corticomotor responsiveness is increased, leading to sustained levels of neuromuscular activity prior to fatigue. In the context of endurance performance, the evidence regarding the central involvement of mouth rinse (MR) in performance improvement is not conclusive. Peripheral mechanisms should not be disregarded, particularly considering factors such as low exercise volume, the participant's fasting state, and the frequency of rinsing. These factors may influence central activations. On the other hand, for strength-related activities, changes in motor evoked potential (MEP) and electromyography (EMG) have been observed, indicating increased corticospinal responsiveness and neuromuscular drive during isometric and isokinetic contractions in both fresh and fatigued muscles. However, it is important to note that in many studies, MEP data were not normalised, making it difficult to exclude peripheral contributions. Voluntary activation (VA), another central measure, often exhibits a lack of changes, mainly due to its high variability, particularly in fatigued muscles. Based on the evidence, MR can attenuate neuromuscular fatigue and improve endurance and strength performance via similar underlying mechanisms. However, the evidence supporting central contribution is weak due to the lack of neurophysiological measures, inaccurate data treatment (normalisation), limited generalisation between exercise modes, methodological biases (ignoring peripheral contribution), and high measurement variability.Trial registration: PROSPERO ID: CRD42021261714.
    Matched MeSH terms: Physical Endurance/physiology; Exercise/physiology; Muscle, Skeletal/physiology; Evoked Potentials, Motor/physiology
  19. Fulltext Allometry and Scaling of the Intraocular Pressure and Aqueous Humour Flow Rate in Vertebrate Eyes
    Zouache MA, Eames I, Samsudin A
    PLoS One, 2016;11(3):e0151490.
    PMID: 26990431 DOI: 10.1371/journal.pone.0151490
    In vertebrates, intraocular pressure (IOP) is required to maintain the eye into a shape allowing it to function as an optical instrument. It is sustained by the balance between the production of aqueous humour by the ciliary body and the resistance to its outflow from the eye. Dysregulation of the IOP is often pathological to vision. High IOP may lead to glaucoma, which is in man the second most prevalent cause of blindness. Here, we examine the importance of the IOP and rate of formation of aqueous humour in the development of vertebrate eyes by performing allometric and scaling analyses of the forces acting on the eye during head movement and the energy demands of the cornea, and testing the predictions of the models against a list of measurements in vertebrates collated through a systematic review. We show that the IOP has a weak dependence on body mass, and that in order to maintain the focal length of the eye, it needs to be an order of magnitude greater than the pressure drop across the eye resulting from gravity or head movement. This constitutes an evolutionary constraint that is common to all vertebrates. In animals with cornea-based optics, this constraint also represents a condition to maintain visual acuity. Estimated IOPs were found to increase with the evolution of terrestrial animals. The rate of formation of aqueous humour was found to be adjusted to the metabolic requirements of the cornea, scaling as Vac(0.67), where Vac is the volume of the anterior chamber. The present work highlights an interdependence between IOP and aqueous flow rate crucial to ocular function that must be considered to understand the evolution of the dioptric apparatus. It should also be taken into consideration in the prevention and treatment of glaucoma.
    Matched MeSH terms: Anterior Chamber/physiology; Aqueous Humor/physiology*; Cornea/physiology; Intraocular Pressure/physiology*
  20. Fulltext Local context influences memory for emotional stimuli but not electrophysiological markers of emotion-dependent attention
    Barnacle GE, Tsivilis D, Schaefer A, Talmi D
    Psychophysiology, 2018 04;55(4).
    PMID: 29023754 DOI: 10.1111/psyp.13014
    Emotional enhancement of free recall can be context dependent. It is readily observed when emotional and neutral scenes are encoded and recalled together in a "mixed" list, but diminishes when these scenes are encoded separately in "pure" lists. We examined the hypothesis that this effect is due to differences in allocation of attention to neutral stimuli according to whether they are presented in mixed or pure lists, especially when encoding is intentional. Using picture stimuli that were controlled for semantic relatedness, our results contradicted this hypothesis. The amplitude of well-known electrophysiological markers of emotion-related attention-the early posterior negativity (EPN), the late positive potential (LPP), and the slow wave (SW)-was higher for emotional stimuli. Crucially, the emotional modulation of these ERPs was insensitive to list context, observed equally in pure and mixed lists. Although list context did not modulate neural markers of emotion-related attention, list context did modulate the effect of emotion on free recall. The apparent decoupling of the emotional effects on attention and memory, challenges existing hypotheses accounting for the emotional enhancement of memory. We close by discussing whether findings are more compatible with an alternative hypothesis, where the magnitude of emotional memory enhancement is, at least in part, a consequence of retrieval dynamics.
    Matched MeSH terms: Attention/physiology*; Brain/physiology*; Emotions/physiology*; Evoked Potentials/physiology*
Related Terms
Filters
Contact Us

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links