Significant Main Effect Of Condition Research Articles

An Evaluation of Personal Cooling Systems for Reducing Thermal Strain Whilst Working in Chemical/Biological Protective Clothing.

ObjectiveThe use of personal cooling systems to mitigate heat strain on first-responders achieves two potential performance benefits relative to the absence of such cooling: (1) the completion of a workload with less effort; and/or (2) the completion of a greater workload for the same effort. Currently, claims made by manufacturers regarding the capability of their products for use in conjunction with chemical/biological protective clothing remain largely unsubstantiated. The purpose of this investigation was to evaluate the means by which heat strain can be alleviated during uncompensable heat stress in chemical/biological clothing, using the ASTM F2300-10 methodology.MethodsEight healthy males completed five trials of continuous walking (4.5 km h−1; 35°C; 49% RH) for up to 120 min while wearing one of four cooling systems and/or a National Fire and Protection Association 1994 Class-3 chemical/biological ensemble. The four cooling methods (ice vest [IV], phase-change vest [PCM], water-perfused suit [WS], and combination ice slurry/ice vest [SLIV]) and no cooling (CON).ResultsWe observed significant improvements in trial times for IV (18 ± 10 min), PCM (20 ± 10 min) and SLIV (22 ± 10 min), but no differences for WS (4 ± 7 min). Heart rate, rectal, mean skin, and body temperatures were significantly lower in all cooling conditions relative to control at various matched time points in the first 60 min of exercise. Thermal sensation, comfort and perceived exertion all had significant main effects for condition, and time, there were no differences in their respective interactions.ConclusionThe IV, PCM, and SLIV produced lower heart rate, mean skin, rectal and mean body temperatures in addition to improved work times compared to control. The WS did not improve work times possibly as a result of the cooling capacity of the suit abating, and magnifying thermal insulation. Considering the added time and resources required to implement combination cooling in the form of ice slurry and ice vest (SLIV), there was no significant additive effect for perception, cardiovascular strain, rectal temperature and total trial time relative to the phase change vest or ice vest alone. This may be a product of a “ceiling” effect for work limit set to 120 min as part of ASTM F2300-10.

Exposure to a sex-specific stressor mitigates sex differences in stress-induced eating

Literature suggests that stress-induced consumption of highly palatable food is a behavior pertaining almost exclusively to women. Given the overall association between stress levels and obesity in the United States transcends sex, it seems likely that males also engage in stress-induced consumption of highly palatable food in certain contexts. In the current study, 168 males and females (54.2% female) were randomly assigned to one of three experimental groups: achievement stress, social rejection stress, and a control condition. Stress was measured with cortisol and respiratory sinus arrhythmia (RSA) reactivity. Post stressor food consumption was measured by weighing several categories of food (highly palatable (sweet, salty), nutritious sweet, nutritious non-sweet, and bland) before and after the participant was introduced to the food items. Males demonstrated greater parasympathetic withdrawal and cortisol reactivity in the achievement condition than females; whereas females demonstrated greater parasympathetic withdrawal and cortisol reactivity in the social rejection condition than males. There were no significant differences in parasympathetic withdrawal between males and females in the control condition. Post-stressor highly palatable food consumption followed this trend. While there was no main effect for sex on the amount of post-stressor highly palatable food consumed, there was a significant main effect for condition and an interaction effect for sex and condition on the amount of post-stressor highly palatable food consumed. Our results challenge the prevailing notion that stress-induced eating of hyper palatable food is mainly found among women by finding that males also engage in such behavior if their experience leads to an adequate stress response.

The Experimental Effects of Acute Exercise Intensity on Episodic Memory and Working Memory Function

The purpose of this study was to evaluate the potential intensity-dependent effects of acute exercise on episodic memory and working memory capacity. A counterbalanced, randomized controlled, within-subject design was employed (N=20; Mage=20.8 yrs). The three counterbalanced visits included a control visit, moderate-intensity exercise (40% of HRR) and high-intensity exercise (70% of HRR). Episodic memory was assessed from a word-list task, including an immediate and delayed (20-min delay) assessment. Working memory capacity was assessed from the Brown-Peterson task. Immediate episodic memory recall was similar across the three conditions (8.5-8.7 words). However, for the 20-min delay period, the high-intensity exercise condition had a higher word recall score than the two other conditions (5.7 vs. 4.9). For the working memory task, there was a statistically significant main effect for condition (F=4.3, P=0.02, η2p=0.18), main effect for delay period (F=30.6, P

The Effect of Anodal Transcranial Direct Current Stimulation Over Left and Right Temporal Cortex on the Cardiovascular Response: A Comparative Study.

Background: Stimulation of the right and left anterior insular cortex, increases and decreases the cardiovascular response respectively, thus indicating the brain’s lateralization of the neural control of circulation. Previous experiments have demonstrated that transcranial direct current stimulation (tDCS) modulates the autonomic cardiovascular control when applied over the temporal cortex. Given the importance of neural control for a normal hemodynamic response, and the potential for the use of tDCS in the treatment of cardiovascular diseases, this study investigated whether tDCS was capable of modulating autonomic regulation.Methods: Cardiovascular response was monitored during a post-exercise muscle ischemia (PEMI) test, which is well-documented to increase sympathetic drive. A group of 12 healthy participants performed a PEMI test in a control (Control), sham (Sham) and two different experimental sessions where the anodal electrode was applied over the left temporal cortex and right temporal cortex with the cathodal electrode placed over the contralateral supraorbital area. Stimulation lasted 20 min at 2 mA. The hemodynamic profile was measured during a PEMI test. The cardiovascular parameters were continuously measured with a transthoracic bio-impedance device both during the PEMI test and during tDCS.Results: None of the subjects presented any side effects during or after tDCS stimulation. A consistent cardiovascular response during PEMI test was observed in all conditions. Statistical analysis did not find any significant interaction and any significant main effect of condition on cardiovascular parameters (all ps > 0.316) after tDCS. No statistical differences regarding the hemodynamic responses were found between conditions and time during tDCS stimulation (p > 0.05).Discussion: This is the first study comparing the cardiovascular response after tDCS stimulation of left and right TC both during exercise and at rest. The results of the current study suggest that anodal tDCS of the left and right TC does not affect functional cardiovascular response during exercise PEMI test and during tDCS. In light of the present and previous findings, the effect of tDCS on the cardiovascular response remains inconclusive.

How to Serve Faster in Tennis: The Influence of an Altered Focus of Attention and Augmented Feedback on Service Speed in Elite Players.

Keller, M, Kuhn, YA, Lüthy, F, and Taube, W. How to serve faster in tennis: the influence of an altered focus of attention and augmented feedback on service speed in elite players. J Strength Cond Res 35(4): 1119-1126, 2021-Different approaches, such as providing augmented feedback (AF) or adopting an external focus of attention (EF), have been shown to directly enhance performance in recreational athletes. Furthermore, research has shown that combining AF with EF (AF + EF) results in superior performance compared to AF and EF alone. Here, we tested the influence of AF, EF, AF + EF, and an internal focus of attention (IF) on service speed in elite tennis players. High-level national tennis players (19.2 ± 3.7 years) were asked to serve flat serves to a target zone with maximum speed. With respect to service speed, a significant main effect of condition was found (p ≤ 0.001). Post hoc comparisons revealed faster serves for AF compared to control serves without instruction/feedback (p < 0.01) and compared to EF (p < 0.05), whereas no significant difference was found between EF and IF (p = 0.81). The fastest service speeds were found in the AF condition, whereas the combination of AF + EF did not further promote performance. The number of serves landed in the target zone did not differ between conditions (p = 0.17). Thus, no speed-accuracy trade-off was found, indicating that enhanced service speeds did not result in less serves landed in the target zone. Augmented feedback seems most beneficial to instantly enhance tennis serve performance. In contrast to previous studies with recreational sportsmen, EF did not differ from IF, providing further evidence that expertise level and task-relevant instructions mediate the influence of attentional focus on motor performance.

Effects of knee extension with different speeds of movement on muscle and cerebral oxygenation.

BackgroundOne of the mechanisms responsible for enhancing muscular hypertrophy is the high metabolic stress associated with a reduced muscular oxygenation occurring during exercise, which can be achieved by reducing the speed of movement. Studies have tested that lowered muscle oxygenation artificially induced by an inflatable cuff, could provoke changes in prefrontal cortex oxygenation, hence, to central fatigue. It was hypothesized that (1) exercising with a slow speed of movement would result in greater increase in cerebral and greater decrease in muscle oxygenation compared with exercises of faster speed and (2) the amount of oxygenation increase in the ipsilateral prefrontal cortex would be lower than the contralateral one.MethodsAn ISS Imagent frequency domain near infrared spectroscopy (NIRS) system was used to quantify oxygenation changes in the vastus lateralis muscle and prefrontal cortex (contra- and ipsilateral) during unilateral resistance exercises with different speeds of movement to voluntary fatigue. After one maximal repetition (1RM) test, eight subjects performed three sets of unilateral knee extensions (∼50% of 1RM), separated by 2 min rest periods, following the pace of 1 s, 3 s and 5 s for both concentric and eccentric phases, in a random order, during separate sessions. The amount of change for NIRS parameters for muscle (ΔHb: deoxyhemoglobin, ΔHbO: oxyhemoglobin, ΔHbT: total hemoglobin, ΔStO2: oxygen saturation) were quantified and compared between conditions and sets by two-way ANOVA RM. Differences in NIRS parameters between contra- and ipsilateral (lobe) prefrontal cortex and conditions were tested.ResultsExercising with slow speed of movement was associated to larger muscle deoxygenation than normal speed of movement, as revealed by significant interaction (set × condition) for ΔHb (p = 0.01), and by significant main effects of condition for ΔHbO (p = 0.007) and ΔStO2 (p = 0.016). With regards to the prefrontal cortex, contralateral lobe showed larger oxygenation increase than the ipsilateral one for ΔHb, ΔHbO, ΔHbT, ΔStO2 in each set (main effect of lobe: p < 0.05). Main effects of condition were significant only in set1 for all the parameters, and significant interaction lobe × condition was found only for ΔHb in set1 (p < 0.05).DiscussionThese findings provided evidence that speed of movement influences the amount of muscle oxygenation. Since the lack of oxygen in muscle is associated to increased metabolic stress, manipulating the speed of movement may be useful in planning resistance-training programs. Moreover, consistent oxygenation increases in both right and left prefrontal lobes were found, suggesting a complementary interaction between the ipsi- and contralateral prefrontal cortex, which also seems related to fatigue.

Influence of Inflatable Anti-fatigue Mats on Center of Pressure Displacement during Prolonged Standing

INTRODUCTION: Many workers are exposed to prolonged periods of standing, which has been linked to musculoskeletal pain, discomfort and other serious health conditions. Additionally, standing desks that do not promote regular bouts of movement may also lead to prolonged standing exposures and increase the risk for pain and discomfort. Traditional foam anti-fatigue mats have been shown to increase foot pressure displacement during prolonged standing and mitigate factors associated with pain and discomfort. However, the purported efficacy of novel inflatable anti-fatigue mats to promote foot pressure displacement has not been investigated. PURPOSE: The aim of this study was to evaluate the effect of inflatable anti-fatigue mats on center of pressure (COP) displacement compared to foam mat and hard surface conditions during prolonged standing. METHODS: 18 healthy individuals (Ht: 1.77±0.11m, Wt: 79.41±19.60kg, Age: 20.5±1.6yrs) stood for one hour on one of three floor conditions: Inflatable mat (IM, 3psi), foam mat (FM; EVA foam, 16mm), and hard surface (HS; force platform). Participants were instructed to stand normally at a standing desk and perform office work tasks with their feet inside the dimensions of the force platform. COP data were collected (1000Hz) for one minute at 0, 15, 30, 45 and 60min. COP data were normalized to foot position, and root mean square COP displacement (RMS) and velocity (RMSv) in the medial-lateral (x) and anterior-posterior (y) directions were calculated as the dependent variables (DV). For each DV a mixed ANOVA was conducted to investigate the between group (condition) and within group (time) differences. RESULTS: A significant main effect of condition was observed for RMSy variable [F (2, 15) = 8.24, p = .004, partial η2 = .52]. Post-hoc tests revealed that IM (2.35±1.10mm) yielded significantly more RMSy than FM (1.13±0.47mm) (p=.016) and HS (0.92±0.32mm) (p=.005). CONCLUSION: The results reveal that inflatable anti-fatigue mats induce greater COP displacement in the anterior-posterior direction compared to hard surfaces and traditional foam mats during one hour of standing. Further research is needed to investigate the relationship between COP displacement and pain/discomfort measures when an inflatable mat is utilized during prolonged standing.

Effects of Aerobic Cycling Exercise in the Heat on Neuromuscular Activation and Fatigue

PURPOSE: To examine the effects of heat on neuromuscular activation and fatigue during aerobic cycling exercise. METHODS: Five recreationally active men (24.8 + 2.9 years; 183.1 + 2.2cm; 80.5 + 4.4kg; 11.3 + 2.8%BF; 3.97 + 0.34 L[BULLET OPERATOR]min-1) visited the laboratory on three separate occasions. Participants completed a VO max test on a Velotron cycle ergometer and underwent skinfold assessment. The remaining two visits consisted of cycling for 60 min at 60% of their previously determined VO2max in either a high- temperature (35°C / 45%RH) (HT), or a moderate-temperature (22°C / 45%) (MT) in a counterbalanced fashion. Electromyography (EMG) of the vastus lateralis of the right leg was recorded during the 60-min exercise protocol during the first two min, and during the last two min of every 10-min period (0-2 min, 8-10 min, 18-20 min, 28-30 min, 38-40 min, 48-50 min, 58-60 min). Raw EMG recordings were normalized to maximal voluntary isometric contractions (MVICs), and analyzed for root mean square (RMS), mean power frequency (MPF) and median power frequency (MEDPF). Data were analyzed using a within-subjects repeated measures ANOVA. RESULTS: No significant interaction (F = 0.519; p = 0.788) or main effects (Time: F = 2.069; p = 0.095; Condition: F = 2.742; p = 0.173) were observed for RMS. Additionally, no interaction was observed for MPF (F = 1.310; p = 0.291), however, a significant main effect of condition was observed for MPF (F = 15.325; p = 0.017), with a significantly higher MPF in HT (91.27 + 3.03%) compared to MT (p = 0.017; 85.00 + 3.07%). A significant main effect of time was also observed for MPF (F = 3.282; p = 0.017), with a significantly higher MPF at 58-60 min (89.30 + 2.86%) compared to 8-10 min (p = 0.039; 86.34 + 2.34%). No significant interaction was observed for MEDPF (F = 1.214; p = 0.333), though a significant main effect of time was observed (F = 2.841; p = 0.031). Pairwise comparisons indicate this difference occurred between 0-2min (82.469 + 3.098%) and 28-30min (p = 0.023; 85.834 + 2.638%). CONCLUSION: Exercise in the heat resulted in a significantly higher MPF, with an increased MPF towards the end of exercise. These data suggest that heat exposure, as well as continuous aerobic exercise, may elicit an increase in action potential conduction velocity over the vastus lateralis.

The Effect of Mental Fatigue on Postural Stability in Young and Older Women

Allocation of attentional resources is required for maintaining postural stability. Fewer attentional resources are available for balance control when individuals perform a dual task paradigm involving concurrent performance of a cognitive task. However, these effects have not been studied under conditions of mental fatigue. PURPOSE To determine if mental fatigue influences postural stability and if there are age differences in stability in response to mental fatigue. METHODS Center of pressure (COP) displacement in response to standing platform perturbations was recorded at the beginning and end of 20 minutes of the psychomotor vigilance task (PVT; mental fatigue condition) and 20 minutes of watching a nature video (control condition) in 16 young (22.4 ± 3.72 years) and 16 older females (72.6 ± 6.50 years). The PVT is a sustained attention task that induces mental fatigue, as indicated by increases in reaction time (RT) to visual stimuli. RESULTS Older adults had a significantly longer RT (325.17 ± 30.90 ms) than young (287.95 ± 29.53 ms) at baseline (p=0.002). Both groups had significantly longer RTs by the end of the PVT task (young 11% increase, p=0.002; older 7% increase, p=0.03), indicating the presence of mental fatigue in the mental fatigue condition. Older adults had a significantly larger anterior-posterior (AP) COP displacement (7.37 ± 0.75 cm) than young adults (5.77± 1.67 cm) at baseline (p =0.001). Nine young and 8 old adults had increases of 0.7-54% in AP COP displacement after the mental fatigue condition. However, there was no significant main effect of condition (p=0.12) nor an interaction of age and condition (p = 0.85) for the percent change in AP COP from the beginning to the end of the session. CONCLUSION These results indicate that although postural control and reaction time performance was worse in older than young at baseline, there was no significant effect of mental fatigue on postural stability in either group.

The Impact of Music and Attentional Focus on Muscular Activation

Neuromuscular efficiency is improved during exercise when attention is focused externally on the effects of movement, rather than internally on the generation of movement. Music is a form of external attentional focus which may yield additional psychological benefits during exercise. The impact of music on neuromuscular efficiency remains to be fully investigated. PURPOSE: To determine the effects of music and other attentional focus conditions on muscular activation and psychological response to single-joint isometric exercise. METHODS: Apparently healthy subjects (N = 23; 12 men) completed an isometric elbow flexion task (40% of predetermined 3RM) for 1 min in three randomized, counterbalanced conditions: internal focus (INT), external focus with a simple distraction task (EXT), and external focus listening to music (MUS). Muscle activation of the biceps (BI) and triceps (TRI) brachii were recorded at 15 s intervals using a 4 channel Delsys EMG system, and were used to compute cocontraction ratio (CCN). Heart rate (HR) was measured throughout the exercise tasks and recorded at 15 s intervals. Psychological characteristics of perceived exertion (RPE), affective valence, task-motivation, and attentional focus were measured at the end of each trial using single-item scales. Repeated measures 3 (condition) x 4 (time) ANOVAs were used to analyze the physiological variables (BI, TRI, CCN, and HR). Psychological variables were compared across conditions using a series of one-way repeated measures ANOVAs. RESULTS: No significant interaction effect or main effect for condition was found for any of the physiological variables (p > .05), though there was a trend (p = .071, η2 = .12) for decreased HR with MUS (91.41 bpm) compared to INT (93.87 bpm). There was a significant main effect of condition on RPE (p = .002, η2 = .25), with a greater RPE in INT (13.87) compared to EXT (12.39) and MUS (12.61). CONCLUSIONS: The primary finding from the current study was that external focus, through both music and a distraction task, reduced the perception of effort during brief single-joint isometric exercise, despite the fact that muscle activation and physiological demand were unchanged.

P.3.008 - N-acetyl cysteine does not modify cognitive markers of compulsivity and impulsivity in an ‘at-risk’ eating-disorder group

N-acetyl cysteine (NAC) is a dietary supplement and glutathione precursor which has shown benefit in the treatment of psychiatric disorders that feature prominent compulsive behaviours such as excoriation and trichotillomania [1]. Eating disorders such as anorexia nervosa and bulimia nervosa also possess compulsive features: both in terms of observed symptoms (binge eating, compulsive exercise, compulsive body-checking), as well as their profile on psychological tasks assessing compulsivity [2]. The aim of this study was to investigate whether performance on cognitive tasks measuring compulsivity, or the related construct of impulsivity [3], could be altered using sub-acute dosing of N-acetyl cysteine in a non-clinical participant group enriched for eating disorder symptomatology. We used a randomised, placebo-controlled, cross-over design with 23 participants (females aged 18-40), who were selected to score between 9 and 19 on the EAT-26 questionnaire [3]. All participants had a BMI of over 18.5, were not taking any psychotropic medication and did not have any formal current psychiatric disorders. Participants received 9 days of either NAC or placebo in randomised order, with a seven-day wash-out period in between. The dose was 1200mg for the first two days, followed by 2400mg for the remaining 7 days. At the end of each 9 day drug/placebo administration period participants completed questionnaires and a number of cognitive tasks. Data were analysed using mixed models, with condition (NAC/Placebo) and order (NAC first or Placebo first) as fixed effects, and participant as a random effect. This was specified in R syntax as lmer(y~order*condition + (1| participants)). Task outcome measures were z-scored. There was no significant main effect of condition on the primary task outcome measure, which was defined as perseverative errors on the WCST: F(1,20) = 1.05, p=0.317. Additionally, there was no significant main effect of condition in the MANOVA of key task outcome measures: F(6,35) = 0.599, p=0.729, see table 1 for data.

A moderate dose of alcohol selectively reduces empathic accuracy

RationaleDrinking alcohol is associated with various interpersonal effects, including effects on cognitive empathy. Empathic accuracy (EA) is a form of cognitive empathy concerned with perceivers’ accuracy in inferring a target’s thoughts and feelings. The effects of alcohol on EA have not previously been studied.ObjectivesWe examined the effect of a moderate alcohol dose on EA in social drinkers.MethodsFifty-four men with varying levels of hazardous drinking according to the Alcohol Use Disorders Identification Test (AUDIT) participated in a randomized, double-blind, between-group study. The alcohol group received 0.56 g/kg alcohol in a vodka and tonic-mixed drink. The placebo group received tonic, with 4 ml of vodka sprayed on top. All participants performed an EA task that involved watching 16 videos of people narrating positive and negative emotional autobiographical events and continuously rating how targets felt while narrating.ResultsThere were no significant main effects of beverage condition on the EA task. There was an effect of the condition by AUDIT interaction for EA on the positive videos. Post-hoc simple contrasts revealed that in participants with lower AUDIT scores, the alcohol condition had lower EA for positive videos than the placebo condition. No significant main effect for condition occurred in the participants with higher AUDIT scores.ConclusionsThe effect of condition in participants with lower AUDIT scores indicates alcohol selectively reduced EA in individuals low on hazardous drinking. This suggests either alcohol-induced impairments of EA for positive events or a positivity bias in men at low risk for alcohol dependency.

Effect of default menus on food selection and consumption in a college dining hall simulation study.

To test an obesity prevention strategy derived from behavioural economics (optimal defaults plus delay), focused on changing the college dining hall service method. After a uniform pre-load, participants attended an experimental lunch in groups randomized to one of three conditions: a nutrient-dense, lower-fat/energy lunch as an optimal default (OD); a less-nutrient-dense, higher-fat/energy lunch as a suboptimal default (SD); or a free array (FA) lunch. In the OD condition, students were presented a menu depicting healthier vegetarian and omnivore foods as default, with opt-out alternatives (SD menu) available on request with a 15 min wait. In the SD condition, the same menu format was used with the positioning of food items switched. In the FA condition, all choices were presented in uniform fonts and were available immediately. Private rooms designed to provide a small version of a college dining hall, on two campuses of a Northeastern US university. First-year college students (n 129). There was a significant main effect for condition on percentage of optimal choices selected, with 94 % of food choices in the OD condition optimal, 47 % in the FA condition optimal and none in the SD condition optimal. Similarly, energy intake for those in the SD condition significantly exceeded that in the FA condition, which exceeded that in the OD condition. Presenting menu items as optimal defaults with a delay had a significant impact on choice and consumption, suggesting that further research into its long-term applicability is warranted.

The acute effects of a multi-ingredient pre-workout supplement on resting energy expenditure and exercise performance in recreationally active females

BackgroundThe use of dietary supplements to improve performance is becoming increasingly popular among athletes and fitness enthusiasts. Unfortunately, there is a tremendous lack of research being done regarding female athletes and the use of sport supplements. The purpose of this study was to examine the acute effects of multi-ingredient pre-workout supplement (MIPS) ingestion on resting metabolism and exercise performance in recreationally-active females.MethodsFifteen recreationally-active females participated in a randomized, double-blind, placebo controlled study. Subjects completed baseline, and two experimental testing sessions in a cross-over design fashion. Experimental testing included assessment of resting energy expenditure (REE), heart rate, and blood pressure following the ingestion of a MIPS or placebo. Subjects also completed a repetition to failure test for the back squat (BS) and bench press (BP) at 85% of their 5-repetition maximum followed by the assessment of anaerobic power using a counter-movement vertical jump test and a sprint test on a force-treadmill. Subjective measurements of energy, focus, and fatigue were also assessed using a 5-point Likert scale. Separate repeated measures analysis of variance (ANOVA) were used to assess differences in REE, cardiovascular responses, and subjective markers between conditions. Performance data were analyzed using paired Student’s T-tests.ResultsA significant main effect for condition was observed for REE (p = 0.021) and diastolic blood pressure (p = 0.011) following ingestion of the MIPS. The supplement condition resulted in a greater number of BP repetitions to failure and total work completed during treadmill test (p = 0.039) compared to placebo (p = 0.037). A significant condition x time interaction for focus was observed with the supplement treatment exhibiting improved focus at 80-min post ingestion (p = 0.046).ConclusionsConsumption of a MIPS increased resting metabolism following a single dose accompanied by an increase in diastolic blood pressure. Furthermore, acute MIPS ingestion improved upper body muscular endurance and anaerobic capacity while improving feelings of focus following high-intensity exercise in recreationally active females.

Increasing mediolateral standing sway is associated with increasing corticospinal excitability, and decreasing M1 inhibition and facilitation

In standing, corticospinal excitability increases and primary motor cortex (M1) inhibition decreases in response to anterior posterior or direction unspecific manipulations that increase task difficulty. However, mediolateral (ML) sway control requires greater active neural involvement. Therefore, the primary purpose of this study was to determine the pattern of change in neural excitability when ML postural task difficulty is manipulated and to test whether the neural excitability is proportional to ML sway magnitude across conditions. Tibialis anterior corticospinal excitability was quantified using motor evoked potential (MEP) and postural sway was indexed using ML center of pressure (COP) velocity. Additionally, we examined inhibition and facilitation processes in the primary motor cortex using the paired pulse short interval intracortical inhibition (SICI) and intracortical facilitation (ICF) techniques respectively. Measurements were repeated in four conditions with quiet stance as a control. Differences between conditions were tested using one-way repeated measures ANOVAs, on log transformed data. Associations were quantified using Spearman’s Rank Correlation Coefficient. There was a significant main effect of condition on all the neural excitability measures with MEP (p<0.001) being highest in the most difficult condition, and SICI (p=0.01), ICF (p<0.001) being lowest in the most difficult condition. Increasing ML COP velocity was significantly associated with increasing MEP amplitude (r=0.68, p<0.001), but decreasing SICI (r=0.24, p=0.03) and ICF (r=−0.54, p<0.001). Our results show that both corticospinal and M1 excitability in standing are scaled in proportion to ML task difficulty.

A test of two alternative cognitive processing models: Learning styles and dual coding

This study tested two cognitive models, learning styles and dual coding, which make contradictory predictions about how learners process and retain visual and auditory information. Learning styles-based instructional practices are common in educational environments despite a questionable research base, while the use of dual coding is less ubiquitous, and thus measured examination of the two methods has implications for practical application. The study involved 204 university students who were surveyed on their preferred learning style and then presented with information that they were prompted to process via either imagery or linguistic means. The results showed there was no significant interaction effect between learning style and condition, suggesting the most basic prediction of the learning styles hypothesis should be rejected. In a regression analysis, none of the four learning styles (visual, auditory, read/write, or kinesthetic) predicted students’ retention of the material. However, there was a highly significant main effect of condition with those in the visual condition retaining twice as much information as those in the auditory condition regardless of learning style, a result that strongly supports dual coding theory. Implications of the findings would suggest that learning styles instruction is an ineffective method for teachers to employ, and that, instead, incorporating principles of dual coding would have a much greater benefit to student learning.

Reduced water intake deteriorates glucose regulation in patients with type 2 diabetes

Epidemiological research has demonstrated that low daily total water intake is associated with increased diagnosis of hyperglycemia. Possible mechanisms for this increase include hormones related to the hypothalamic pituitary axis as well as the renin-angiotensin-aldosterone system (RAAS). Therefore, the hypothesis of the present study was that acute low water intake would result in differential hormonal profiles and thus impaired blood glucose regulation during an oral glucose tolerance test (OGTT) in people with type 2 diabetes mellitus (T2DM). Nine men (53 ± 9 years, 30.0 ± 4.3 m∙kg−2, 32% ± 6% body fat) diagnosed with T2DM completed OGTTs in euhydrated (EUH) and hypohydrated (HYP) states in counterbalanced order. Water restriction led to hypohydration of −1.6% of body weight, with elevated plasma (EUH: 288 ± 4, HYP: 298 ± 6 mOsm·kg−1; P < .05) and urine (EUH: 512 ± 185, HYP: 994 ± 415 mOsm·kg−1; P < .05) osmolality. There was a significant main effect of condition for serum glucose (at time 0 minute 9.5 ± 4.2 vs 10.4 ± 4.4 mmol∙L−1 and at time 120 minutes 19.1 ± 4.8 vs 21.0 ± 4.1 mmol∙L−1 for EUH and HYP, respectively; P < .001) but not insulin (mean difference between EUH and HYP −12.1 ± 44.9 pmol∙L−1, P = .390). An interaction between time and condition was observed for cortisol: decrease from minute 0 to 120 in EUH (−85.3 ± 82.1 nmol∙L−1) vs HYP (−25.0 ± 43.0 nmol∙L−1; P = .017). No differences between conditions were found within RAAS-related hormones. Therefore, we can conclude that 3 days of low total water intake in people with T2DM acutely impairs blood glucose response during an OGTT via cortisol but not RAAS-mediated glucose regulation.

Effects Of Lower-body Versus Upper- And Lower-body Resistance Exercise On Lower-body Intramuscular Temperature

PURPOSE: Intramuscular temperatures above 38.6° C are associated with impaired endurance. However, the effects of resistance exercise on intramuscular temperature has not been studied. Further, some studies have shown that exercise in one muscle group can impair performance in other muscles. Thus, the purpose of this study was to compare the effects of lower-body (LB) only and lower-body with upper-body (UB) resistance exercise on intramuscular temperature of the vastus lateralis. METHODS: Ten subjects (age=19.9±2.4 y; height=179.1±8.6 cm; mass=81.4±7.7 kg) participated in the study. Experimental visits consisted of either a LB or (UB) condition. During UB, participants completed three circuits of 90% one-repetition maximum (1RM) hip sled and 80% 1RM lat pull-down exercises to failure followed by a final 90% 1RM hip sled set to failure. During LB, participants completed four sets of hip sled to failure at 90% of 1RM. The beginning of each hip sled set was separated by 4-minutes. For all sets a thermocouple sampled vastus lateralis temperature. For all statistical analyses, alpha was set at .05. RESULTS: A 2 (condition) by 4 (set) by 2 [intra-set change (start versus end)] repeated measures ANOVA revealed a significant interaction between set and intra-set change on muscle temperature (p=.001; η2=.647); there were no other significant interactions. Collapsed across conditions, intra-set muscle temperature increases were progressively attenuated (highest p=.006) from a maximum of .5°±.2 in set 1 to .2°±.2 in set 4. There was no significant main effect of condition on muscle temperature (p=.257; η2=.140). Two one-sample t-tests showed that muscle temperature at the end of set 4 was significantly less than 38.6° in the LB (CI=35.6-37.2°; p<.001) and UB (CI=35.2-36.6°; p<.001) conditions. A 2 (condition) by 4 (set) repeated measures ANOVA yielded no significant main effect of condition on total number of completed hip sled repetitions (p=.494; η2=.053; LB CI=6.5-10.8 reps; UB CI=5.7-10.5). CONCLUSIONS: During resistance exercise, it is unlikely that muscle temperatures get high enough to enhance the rate of fatigue development. Furthermore, the addition of UB resistance exercise does not appear to significantly increase LB muscle temperature or affect performance under these conditions.

Attentional capture by physically salient stimuli in the gamma frequency is associated with schizophrenia symptoms

Objectives: Aberrant salience mainly is attributed to excessive dopaminergic processing in the ventral striatum. Increased gamma power during sensory processing of physical salience has been shown to be associated with positive trait schizotypy. In the present study, this is assessed in patients with schizophrenia.Methods: The early evoked visual gamma-band response (GBR) at 40 Hz was assessed for a schizophrenia patient group (N = 22) and a matched healthy control group (N = 22) applying EEG time-frequency analysis. The GBR was assessed for two conditions within a visual detection paradigm: a target with or without a physically salient distracter and evaluated in relation to the PANSS.Results: A 2 × 2 ANOVA revealed a significant main effect of condition and a trend interaction of group and condition for the GBR, with highest power for schizophrenia patients in the physically salient distracter condition. Moreover, evoked GBR power in this condition was correlated with positive (r = 0.664; P = 0.001**) and disorganised (r = 0.618; P = 0.002**) schizophrenia symptoms.Conclusions: Evoked GBR power during processing of physical salience in schizophrenia was associated with positive symptoms. We suggest that abnormal processing of physically salient stimuli might be involved in the pathophysiological genesis of positive symptoms.

Effect of acute contract-relax proprioceptive neuromuscular facilitation stretching on static balance in healthy men

Summary Objective Muscle stretching is plenty used prior to training and competition. Considering the importance of balance control in performance, muscle stretching is expected to have positive effects on balance. However, there is a lack of studies investigating the effects of contract-relax proprioceptive neuromuscular facilitation (CR PNF) stretching on balance control. The purpose of this study was to investigate the effects of CR PNF stretching on static postural balance. Methods Fourteen subjects were tested before and after a 5-minute cycle warm-up followed by 10 minutes of CR PNF stretching (stretching condition) and the same cycle warm-up with 10-minute rest periods (control condition). The four muscle groups stretched were the quadriceps, hamstrings, anterior tibialis, and calf muscles of both legs in an alternating manner. Postural balance was assessed in a bipedal static stance before and after each condition with eyes opened (EO) and eyes closed (EC). Results No significant interactions for any postural parameters. However, there was a significant main effect of condition for sway area (P 0.05). Conclusion It appears that the stretching and control conditions impaired static balance control by increasing postural sway. CR PNF stretching was unable to compensate for the warm-up and its effects of induced alteration in postural balance.