Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 18.091
Filtrar
1.
Medicina (Kaunas) ; 57(9)2021 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-34577899

RESUMO

Background and Objectives: The passive nature of rest breaks in sport could reduce athletes' performance and even increase their risk of injury. Re-warm-up activities could help avoid these problems, but there is a lack of research on their efficacy. This systematic review aimed at analyzing the results of those randomized controlled trials (RCTs) that provided information on the effects of re-warm-up strategies. Materials and Methods: Four electronic databases (Web of Science, Scopus, PubMed, and SPORTDiscus) were searched from their inception to January 2021, for RCTs on the effects of re-warm-up activities on sports performance. Interventions had to be implemented just after an exercise period or sports competition. Studies that proposed activities that were difficult to replicate in the sport context or performed in a hot environment were excluded. Data were synthesized following PRISMA guidelines, while the risk of bias was assessed following the recommendations of the Cochrane Collaboration. Results: A total of 14 studies (178 participants) reporting data on acute or short-term effects were analyzed. The main outcomes were grouped into four broad areas: physiological measures, conditional abilities, perceptual skills, and sport efficiency measures. The results obtained indicated that passive rest decreases physiological function in athletes, while re-warm-up activities could help to improve athletes' conditional abilities and sporting efficiency, despite showing higher fatigue levels in comparison with passive rest. The re-warm-up exercise showed to be more effective than passive rest to improve match activities and passing ability. Conclusions: Performing re-warm-up activities is a valuable strategy to avoid reducing sports performance during prolonged breaks. However, given that the methodological quality of the studies was not high, these relationships need to be further explored in official or simulated competitions.


Assuntos
Desempenho Atlético , Atletas , Exercício Físico , Humanos , Descanso
2.
Neurosci Biobehav Rev ; 129: 367-388, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34371078

RESUMO

Experience-related brain activity patterns reactivate during sleep, wakeful rest, and brief pauses from active behavior. In parallel, machine learning research has found that experience replay can lead to substantial performance improvements in artificial agents. Together, these lines of research suggest that replay has a variety of computational benefits for decision-making and learning. Here, we provide an overview of putative computational functions of replay as suggested by machine learning and neuroscientific research. We show that replay can lead to faster learning, less forgetting, reorganization or augmentation of experiences, and support planning and generalization. In addition, we highlight the benefits of reactivating abstracted internal representations rather than veridical memories, and discuss how replay could provide a mechanism to build internal representations that improve learning and decision-making.


Assuntos
Hipocampo , Vigília , Humanos , Descanso , Sono
3.
Sensors (Basel) ; 21(15)2021 Jul 31.
Artigo em Inglês | MEDLINE | ID: mdl-34372457

RESUMO

This study sought to evaluate the training load in different age category soccer players associated with distinct pitch size small-sided games (SSGs). Twenty-four soccer players (eight in each age category: U-12, U-15, and U-23) performed three consecutive 4 vs. 4 ball possession SSGs (SSG1: 16 × 24 m; SSG2: 20 × 30 m; and SSG3: 24 × 36 m) all with 3 min duration and 3 min rest. Subjects carried ultra-wideband-based position-tracking system devices (WIMU PRO, RealTrack System). Total distance covered increased from SSG1 to SSG3 in all age categories and predominantly in running speeds below 12 km·h-1. Moreover, distance covered in 12-18 km·h-1 running speed was different in all performed SSGs and age categories. Residual or null values were observed at 18-21 km·h-1 or above running speed, namely in U-12, the only age category where metabolic power and high metabolic load distance differences occurred throughout the performed SSGs. Edwards' TRIMP differences between age categories was only observed in SSG2 (U-12 < U-15). The design of SSGs must consider that the training load of the players differs according to their age category and metabolic assessment should be considered in parallel to external load evaluation in SSGs. Wearable technology represents a fundamental support in soccer.


Assuntos
Desempenho Atlético , Corrida , Futebol , Progressão da Doença , Frequência Cardíaca , Humanos , Descanso
4.
Neuroscience ; 472: 25-34, 2021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34333062

RESUMO

Studying the nonlinear synchronization of electroencephalogram (EEG) in type 2 diabetic mellitus (T2DM) to find the EEG characteristics related to cognitive impairment is beneficial to the early prevention and diagnosis of mild cognitive impairment. Correlation between probabilities of recurrence (CPR) is a nonlinear phase synchronization method based on recurrence and recurrence probability, which had shown its superiority in detecting epilepsy. In this study, CPR method was used for the first time to analyze the synchronization of eye-closed resting EEG signals with T2DM. The 27 participants were divided into amnesic mild cognitive impairment (aMCI) group (17 case) and control group (10 cases with age and education matched). The CPR values in two groups were statistically analyzed by Mann-Whitney U test, and the correlation between EEG synchronization and cognitive function was studied by Spearman's correlation. The results showed that aMCI group had lower CPR values at each electrode pair than control group, and two groups had decreased CPR values with the increase of the spatial distance of the electrode pair in inter hemispheric. The CPR values were significantly different in frontal, parietal and temporal regions in intra hemispheric between two groups. The CPR values of C3-F7, F4-C4 and FP2-T6 were significantly positively correlated with the MOCA values. This study showed that the synchronization values of EEG signals obtained by the CPR method were significantly different between aMCI and control group, and they were the EEG characteristics associated with cognitive impairment in T2DM.


Assuntos
Disfunção Cognitiva , Diabetes Mellitus Tipo 2 , Epilepsia , Disfunção Cognitiva/diagnóstico , Disfunção Cognitiva/etiologia , Diabetes Mellitus Tipo 2/complicações , Eletroencefalografia , Humanos , Descanso
5.
Pain ; 162(9): 2397-2404, 2021 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-34448753

RESUMO

ABSTRACT: Pain is a subjective experience with significant individual differences. Laboratory studies investigating pain thresholds and experimental acute pain have identified structural and functional neural correlates. However, these types of pain stimuli have limited ecological validity to real-life pain experiences. Here, we use an orthodontic procedure-the insertion of an elastomeric separator between teeth-which typically induces mild to moderate pain that peaks within 2 days and lasts several days. We aimed to determine whether the baseline structure and resting-state functional connectivity of key regions along the trigeminal nociceptive and pain modulatory pathways correlate with subsequent peak pain ratings. Twenty-six healthy individuals underwent structural and resting-state functional MRI scanning before the placement of a separator between the first molar and second premolar, which was kept in place for 5 days. Participants recorded pain ratings 3 times daily on a 100-mm visual analogue scale. Peak pain was not significantly correlated with diffusion metrics of the trigeminal nerve or gray matter volume of any brain region. Peak pain did, however, positively correlate with baseline resting-state functional connectivity between the thalamus contralateral to the separator and bilateral insula, and negatively correlated with connectivity between the periaqueductal gray (PAG) and core nodes of the default mode network (medial prefrontal and posterior cingulate cortices). The ascending (thalamic) nociceptive and the descending (PAG) pain modulatory pathways at baseline each explained unique variation in peak pain intensity ratings. In sum, preinterventional functional neural architecture of both systems determined the individual pain experience to a subsequent ecologically valid pain stimulus.


Assuntos
Dor Aguda , Descanso , Dor Facial , Humanos , Imageamento por Ressonância Magnética , Modelos Teóricos
6.
Brain Inj ; 35(9): 1086-1094, 2021 07 29.
Artigo em Inglês | MEDLINE | ID: mdl-34334071

RESUMO

BACKGROUND: There is little knowledge about rest-activity cycles (RAC) in patients with severe-acquired brain injury (sABI) during early in-hospital rehabilitation. This study aimed to investigate if patients with sABI displayed unconsolidated RACs at the beginning of in-hospital rehabilitation, and how these changed over time. METHODS: This study was a prospective observational study. All patients consecutively admitted to one ward were screened for eligibility. We recorded accelerometric activity for 20 days. The Daytime Activity Ratio (DAR) of activity between daytime (7-22) and the total activity during the entire day was calculated and used to estimate consolidation. RESULTS: Fifty-five patients were screened and 20 patients were included. Complete day 1 & 2 data was obtained on 18 patients. Fifty-six percentage of these had a consolidated RAC at the beginning of rehabilitation. On day 19 & 20, complete data could be obtained from 15 patients, 80% of these had consolidation of RAC. When comparing these a significant mean increase of 5.8% 95%CI(0.52; 11.01) in DAR was found p < .05, and the model of all data also showed a significant increase in median DAR over time p < .01. CONCLUSION: RAC consolidation improves over time in patients admitted for in-hospital early neurorehabilitation.


Assuntos
Lesões Encefálicas , Reabilitação Neurológica , Ciclos de Atividade , Hospitalização , Humanos , Descanso
7.
Am J Cardiol ; 155: 45-51, 2021 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-34284867

RESUMO

Resting heart rate (RHR) has been an established predictor for atrial fibrillation (AF). However, the association of visit-to-visit heart rate variability (VVHRV) with new-onset AF risk over long term remains unclear. Our study investigates the relation of VVHRV to new-onset AF in general population in the prospective study of the Kailuan cohort. A total of 46,126 individuals without arrhythmia were included. They underwent 3 health examinations from 2006 to 2010 and performed follow up. VVHRV was measured by coefficient of variation (CV), variability independent of the mean (VIM), and standard deviation (SD). Participants were separately divided into 5 categories by quintiles of visit-to-visit RHR-CV, RHR-VIM and RHR-SD. Multivariate Cox regression and restricted cubic spline models were performed to establish the association between VVHRV and new-onset AF. 241 new-onset AF occurred during a median follow-up of 7.54 years. The incidence of new-onset AF in the group of the lowest (Q1) and highest quintiles (Q5) of RHR-CV were higher than that in other groups. The HRs for the new-onset AF were 2.07 (95% CI, 1.34-3.21, p < 0.01), in the highest quintile group(Q5) compared with group Q2, and 1.89(95% CI, 1.20-2.97, p < 0.01) in the lowest quintile group(Q1) compared with group Q2. The risk for new-onset AF showed a similar trend using RHR-VIM (p < 0.01) and RHR-SD (p < 0.05) parameters. Further sensitivity analyses indicated the consistent results in subjects without prior cardiovascular disease and without taking beta blockers or CCB. To match the covariates, analyses were also performed by propensity score matching, and prominent trends were also found in RHR-SD and RHR-VIM. In conclusion, the study indicated that higher and lower VVHRV were associated with the increasing risk of new-onset AF, which supporting a U-shaped curve existence.


Assuntos
Fibrilação Atrial/epidemiologia , Frequência Cardíaca/fisiologia , Visita a Consultório Médico/estatística & dados numéricos , Vigilância da População , Descanso/fisiologia , Fibrilação Atrial/fisiopatologia , China/epidemiologia , Feminino , Seguimentos , Humanos , Incidência , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Fatores de Risco
8.
Radiology ; 301(1): 178-184, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34282966

RESUMO

Background Resting-state functional MRI (rs-fMRI) is a potential alternative to task-based functional MRI (tb-fMRI) for somatomotor network (SMN) identification. Brain networks can also be generated from tb-fMRI by using independent component analysis (ICA). Purpose To investigate whether the SMN can be identified by using ICA from a language task without a motor component, the sentence completion functional MRI (sc-fMRI) task, compared with rs-fMRI. Materials and Methods The sc-fMRI and rs-fMRI scans in patients who underwent presurgical brain mapping between 2012 and 2016 were analyzed, using the same imaging parameters (other than scanning time) on a 3.0-T MRI scanner. ICA was performed on rs-fMRI and sc-fMRI scans with use of a tool to separate data sets into their spatial and temporal components. Two neuroradiologists independently determined the presence of the dorsal SMN (dSMN) and ventral SMN (vSMN) on each study. Groups were compared by using t tests, and logistic regression was performed to identify predictors of the presence of SMNs. Results One hundred patients (mean age, 40.9 years ± 14.8 [standard deviation]; 61 men) were evaluated. The dSMN and vSMN were identified in 86% (86 of 100) and 76% (76 of 100) of rs-fMRI scans and 85% (85 of 100) and 69% (69 of 100) of sc-fMRI scans, respectively. The concordance between rs-fMRI and sc-fMRI for presence of dSMN and vSMN was 75% (75 of 100 patients) and 53% (53 of 100 patients), respectively. In 10 of 14 patients (71%) where rs-fMRI did not show the dSMN, sc-fMRI demonstrated it. This rate was 67% for the vSMN (16 of 24 patients). Conclusion In the majority of patients, independent component analysis of sentence completion task functional MRI scans reliably demonstrated the somatomotor network compared with resting-state functional MRI scans. Identifying target networks with a single sentence completion scan could reduce overall functional MRI scanning times by eliminating the need for separate motor tasks. © RSNA, 2021 Online supplemental material is available for this article. See also the editorial by Field and Birn in this issue.


Assuntos
Mapeamento Encefálico/métodos , Neoplasias Encefálicas/diagnóstico por imagem , Imageamento por Ressonância Magnética/métodos , Córtex Motor/diagnóstico por imagem , Adulto , Encéfalo/diagnóstico por imagem , Feminino , Humanos , Idioma , Masculino , Reprodutibilidade dos Testes , Descanso
10.
J Psychiatr Res ; 141: 233-240, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34256274

RESUMO

For several decades, resting electroencephalogram (EEG) alpha oscillations have been used to characterize neurophysiological alterations related to major depressive disorder. Prior research has generally focused on frontal alpha power and asymmetry despite resting alpha being maximal over posterior electrode sites. Research in depressed adults has shown evidence of hemispheric asymmetry for posterior alpha power, however, the resting posterior alpha-depression link among adolescents remains unclear. To clarify the role of posterior alpha among depressed adolescents, the current study acquired eyes-closed 128-channel resting EEG data from 13 to 18 year-old depressed (n = 31) and healthy (n = 35) female adolescents. Results indicated a significant group by hemisphere interaction, as depressed adolescents exhibited significantly larger posterior alpha (i.e., lower brain activity) over the right versus left hemisphere, whereas healthy adolescents showed no hemispheric differences. Relatively greater alpha over the right versus left hemisphere correlated with depression symptoms, anhedonia symptoms, rumination, and self-criticism. Further, depressed adolescents had reduced overall posterior alpha compared to healthy youth; though, no associations with symptoms and related traits emerged. Resting posterior alpha may be a promising neurophysiological index of adolescent depression, and more broadly, may relate to risk factors characterized by enhanced perseveration.


Assuntos
Transtorno Depressivo Maior , Adolescente , Adulto , Ritmo alfa , Eletroencefalografia , Feminino , Humanos , Descanso , Fatores de Risco
11.
Sensors (Basel) ; 21(13)2021 Jul 04.
Artigo em Inglês | MEDLINE | ID: mdl-34283143

RESUMO

Freehand exercises help improve physical fitness without any requirements for devices or places. Existing fitness assistant systems are typically restricted to wearable devices or exercising at specific positions, compromising the ubiquitous availability of freehand exercises. In this paper, we develop MobiFit, a contactless freehand exercise assistant using just one cellular signal receiver placed on the ground. MobiFit passively monitors the ubiquitous cellular signals sent by the base station, which frees users from the space constraints and deployment overheads and provides accurate repetition counting, exercise type recognition and workout quality assessment without any attachments to the human body. The design of MobiFit faces new challenges of the uncertainties not only on cellular signal payloads but also on signal propagations because the sender (base station) is beyond the control of MobiFit and located far away. To tackle these challenges, we conducted experimental studies to observe the received cellular signal sequence during freehand exercises. Based on the observations, we constructed the analytic model of the received signals. Guided by the insights derived from the analytic model, MobiFit segments out every repetition and rest interval from one exercise session through spectrogram analysis and extracts low-frequency features from each repetition for type recognition. Extensive experiments were conducted in both indoor and outdoor environments, which collected 22,960 exercise repetitions performed by ten volunteers over six months. The results confirm that MobiFit achieves high counting accuracy of 98.6%, high recognition accuracy of 94.1% and low repetition duration estimation error within 0.3 s. Besides, the experiments show that MobiFit works both indoors and outdoors and supports multiple users exercising together.


Assuntos
Exercício Físico , Dispositivos Eletrônicos Vestíveis , Terapia por Exercício , Humanos , Monitorização Fisiológica , Descanso
12.
J Alzheimers Dis ; 82(3): 1085-1114, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34151788

RESUMO

BACKGROUND: In relaxed adults, staying in quiet wakefulness at eyes closed is related to the so-called resting state electroencephalographic (rsEEG) rhythms, showing the highest amplitude in posterior areas at alpha frequencies (8-13 Hz). OBJECTIVE: Here we tested the hypothesis that age may affect rsEEG alpha (8-12 Hz) rhythms recorded in normal elderly (Nold) seniors and patients with mild cognitive impairment due to Alzheimer's disease (ADMCI). METHODS: Clinical and rsEEG datasets in 63 ADMCI and 60 Nold individuals (matched for demography, education, and gender) were taken from an international archive. The rsEEG rhythms were investigated at individual delta, theta, and alpha frequency bands, as well as fixed beta (14-30 Hz) and gamma (30-40 Hz) bands. Each group was stratified into three subgroups based on age ranges (i.e., tertiles). RESULTS: As compared to the younger Nold subgroups, the older one showed greater reductions in the rsEEG alpha rhythms with major topographical effects in posterior regions. On the contrary, in relation to the younger ADMCI subgroups, the older one displayed a lesser reduction in those rhythms. Notably, the ADMCI subgroups pointed to similar cerebrospinal fluid AD diagnostic biomarkers, gray and white matter brain lesions revealed by neuroimaging, and clinical and neuropsychological scores. CONCLUSION: The present results suggest that age may represent a deranging factor for dominant rsEEG alpha rhythms in Nold seniors, while rsEEG alpha rhythms in ADMCI patients may be more affected by the disease variants related to earlier versus later onset of the AD.


Assuntos
Envelhecimento/fisiologia , Ritmo alfa/fisiologia , Doença de Alzheimer/diagnóstico por imagem , Amnésia/diagnóstico por imagem , Cognição/fisiologia , Disfunção Cognitiva/diagnóstico por imagem , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/psicologia , Doença de Alzheimer/fisiopatologia , Doença de Alzheimer/psicologia , Amnésia/fisiopatologia , Amnésia/psicologia , Disfunção Cognitiva/fisiopatologia , Disfunção Cognitiva/psicologia , Eletroencefalografia/métodos , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Pessoa de Meia-Idade , Descanso/fisiologia , Descanso/psicologia
13.
Biol Psychol ; 163: 108137, 2021 07.
Artigo em Inglês | MEDLINE | ID: mdl-34139311

RESUMO

Resting frontal EEG alpha asymmetry has been extensively examined as a marker of motivational disposition. Recent research has examined how this trait-level marker of motivation influences an individual's internal error monitoring (indexed by the error-related negativity; ERN), with mixed findings as to whether more negative ERNs are associated with greater left or right alpha power. Data from 339 children who completed an incentivized Go/No-Go task annually from Kindergarten through 2nd grade were examined for an association between ERN amplitude and EEG asymmetry, and for whether the association was developmentally stable. Results indicate an association between left-dominant activation and a more negative amplitude in Kindergarten, with an inversion of this association emerging by 2nd grade, such that a more negative ERNs were associated with right-dominant activation. We suggest that the association between EEG asymmetry and ERN amplitude is likely modulated by task condition (e.g., incentivization) and experience over time (e.g., habituation).


Assuntos
Eletroencefalografia , Motivação , Criança , Potenciais Evocados , Humanos , Personalidade , Descanso
14.
PLoS Biol ; 19(6): e3001275, 2021 06.
Artigo em Inglês | MEDLINE | ID: mdl-34077415

RESUMO

Episodic memory depends on interactions between the hippocampus and interconnected neocortical regions. Here, using data-driven analyses of resting-state functional magnetic resonance imaging (fMRI) data, we identified the networks that interact with the hippocampus-the default mode network (DMN) and a "medial temporal network" (MTN) that included regions in the medial temporal lobe (MTL) and precuneus. We observed that the MTN plays a critical role in connecting the visual network to the DMN and hippocampus. The DMN could be further divided into 3 subnetworks: a "posterior medial" (PM) subnetwork comprised of posterior cingulate and lateral parietal cortices; an "anterior temporal" (AT) subnetwork comprised of regions in the temporopolar and dorsomedial prefrontal cortex; and a "medial prefrontal" (MP) subnetwork comprised of regions primarily in the medial prefrontal cortex (mPFC). These networks vary in their functional connectivity (FC) along the hippocampal long axis and represent different kinds of information during memory-guided decision-making. Finally, a Neurosynth meta-analysis of fMRI studies suggests new hypotheses regarding the functions of the MTN and DMN subnetworks, providing a framework to guide future research on the neural architecture of episodic memory.


Assuntos
Hipocampo/fisiologia , Rede Nervosa/fisiologia , Humanos , Memória/fisiologia , Descanso/fisiologia , Análise e Desempenho de Tarefas , Lobo Temporal/fisiologia , Vias Visuais/fisiologia
15.
Neurosci Biobehav Rev ; 128: 406-414, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34186152

RESUMO

Supernatural fears, although common, are not as well-understood as natural fears and phobias (e.g., social, blood, and animal phobias) which are prepared by evolution, such that they are easily acquired through direct experience and relatively immune to cognitive mediation. In contrast, supernatural fears do not involve direct experience but seem to be related to sensory or cognitive biases in the interpretation of stimuli as well as culturally driven cognitions and beliefs. In this multidisciplinary synthesis and collaborative review, we claim that supernatural beliefs are "super natural." That is, they occur spontaneously and are easy to acquire, possibly because such beliefs rest on intuitive concepts such as mind-body dualism and animism, and may inspire fear in believers as well as non-believers. As suggested by psychological and neuroscientific evidence, they tap into an evolutionarily prepared fear of potential impending dangers or unknown objects and have their roots in "prepared fears" as well as "cognitively prepared beliefs," making fear of supernatural agents a fruitful research avenue for social, anthropological, and psychological inquires.


Assuntos
Medo , Transtornos Fóbicos , Cognição , Humanos , Descanso
16.
J Sci Med Sport ; 24(8): 793-799, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34112612

RESUMO

OBJECTIVES: To examine, 1) optimal structure of break periods to mitigate physiological heat strain during rugby league play (Stage 1); and ii) effectiveness of three different cooling strategies applied during breaks (Stage 2). DESIGN: Counter-balanced crossover design. METHODS: In 37 °C, 50% RH, 11 males completed six simulated 80-min (two 40-min halves) rugby league matches on a treadmill with different break structures: regular game (RG) (12-min halftime), 1-min or 3-min "quarter-time" breaks halfway through each half with a 12-min halftime break (R1C and R3C), a 20-min halftime break (EH), or 1-min or 3-min quarter-time breaks with a 20-min halftime break (E1C and E3C) [Stage 1]. Nine participants completed Stage 2, which assessed the application of either ice towels (ICE), an electric fan (FAN) or a misting fan (MST) during breaks in the E3C protocol which, in Stage 1, prevailed as the optimal break structure. RESULTS: Stage 1: Irrespective of quarter-time break duration, reductions in rectal temperature (-0.24 °C ±â€¯0.24) and heart rate (-61 ±â€¯10 bpm) during the halftime break were greater with a 20-min compared to a 12-min break (-0.08 ±â€¯0.13 °C, p = 0.005; -55 ±â€¯-9 bpm, p = 0.021). Stage 2: End-game rises in rectal temperature were smaller (p < 0.006) in MST (1.41 ±â€¯0.22 °C), FAN (1.55 ±â€¯0.36 °C) and ICE (1.60 ±â€¯0.21 °C) than in CON (1.80 ±â€¯0.39 °C). The end-halftime heart rate was lower (p < 0.001) in ICE (89 ±â€¯13 bpm), MST (90 ±â€¯10 bpm) and FAN (92 ±â€¯13 bpm) than in CON (99 ±â€¯18 bpm). CONCLUSIONS: Combining an extended halftime period and quarter-time breaks with MST application is the optimal cooling strategy for rugby league players in hot, humid conditions.


Assuntos
Regulação da Temperatura Corporal , Crioterapia/métodos , Futebol Americano/fisiologia , Transtornos de Estresse por Calor/prevenção & controle , Resposta ao Choque Térmico , Temperatura Alta , Estudos Cross-Over , Frequência Cardíaca , Humanos , Umidade , Gelo , Masculino , Percepção/fisiologia , Esforço Físico/fisiologia , Descanso , Sensação Térmica , Fatores de Tempo
17.
J Sci Med Sport ; 24(8): 774-780, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34158232

RESUMO

OBJECTIVES: To investigate the efficacy of heat acclimation (HA) in the young (YEX) and elderly (EEX) following exercise-HA, and the elderly utilising post-exercise hot water immersion HA (EHWI). DESIGN: Cross-sectional study. METHOD: Twenty-six participants (YEX: n = 11 aged 22 ±â€¯2 years, EEX:n = 8 aged 68 ±â€¯3 years, EHWI: n = 7 aged 73 ±â€¯3 years) completed two pre-/post-tests, separated by five intervention days. YEX and EEX exercised in hot conditions to raise rectal temperature (Trec) ≥38.5 °C within 60 min, with this increase maintained for a further 60 min. EHWI completed 30 min of cycling in temperate conditions, then 30 min of HWI (40 °C), followed by 30 min seated blanket wrap. Pre- and post-testing comprised 30 min rest, followed by 30 min of cycling exercise (3.5 W·kg-1 Hprod), and a six-minute walk test (6MWT), all in 35 °C, 50% RH. RESULTS: The HA protocols did not elicit different mean heart rate (HR), Trec, and duration Trec ≥ 38.5 °C (p > 0.05) between YEX, EEX, and EHWI groups. Resting Trec, peak skin temperature, systolic and mean arterial pressure, perceived exertion and thermal sensation decreased, and 6MWT distance increased pre- to post-HA (p < 0.05), with no difference between groups. YEX also demonstrated a reduction in resting HR (p < 0.05). No change was observed in peak Trec or HR, vascular conductance, sweat rate, or thermal comfort in any group (p > 0.05). CONCLUSIONS: Irrespective of age or intervention, HA induced thermoregulatory, perceptual and exercise performance improvements. Both exercise-HA (EEX), and post-exercise HWI (EHWI) are considered viable interventions to prepare the elderly for heat stress.


Assuntos
Aclimatação , Envelhecimento/fisiologia , Exercício Físico/fisiologia , Resposta ao Choque Térmico , Temperatura Alta , Imersão , Idoso , Pressão Sanguínea , Estudos Transversais , Feminino , Frequência Cardíaca , Transtornos de Estresse por Calor/prevenção & controle , Humanos , Masculino , Percepção/fisiologia , Esforço Físico/fisiologia , Descanso , Temperatura Cutânea , Sudorese , Sensação Térmica , Adulto Jovem
18.
Neuroimage Clin ; 31: 102726, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34153687

RESUMO

Understanding the interrelationships of clinical manifestations of Alzheimer's disease (AD) and functional connectivity (FC) as the disease progresses is necessary for use of FC as a potential neuroimaging biomarker. Degradation of resting-state networks in AD has been observed when FC is estimated over the entire scan, however, the temporal dynamics of these networks are less studied. We implemented a novel approach to investigate the modular structure of static (sFC) and time-varying (tvFC) connectivity along the AD spectrum in a two-sample Discovery/Validation design (n = 80 and 81, respectively). Cortical FC networks were estimated across 4 diagnostic groups (cognitively normal, subjective cognitive decline, mild cognitive impairment, and AD) for whole scan (sFC) and with sliding window correlation (tvFC). Modularity quality (across a range of spatial scales) did not differ in either sFC or tvFC. For tvFC, group differences in temporal stability within and between multiple resting state networks were observed; however, these differences were not consistent between samples. Correlation analyses identified a relationship between global cognition and temporal stability of the ventral attention network, which was reproduced in both samples. While the ventral attention system has been predominantly studied in task-evoked designs, the relationship between its intrinsic dynamics at-rest and general cognition along the AD spectrum highlights its relevance regarding clinical manifestation of the disease.


Assuntos
Doença de Alzheimer , Disfunção Cognitiva , Doença de Alzheimer/diagnóstico por imagem , Cognição , Disfunção Cognitiva/diagnóstico por imagem , Humanos , Imageamento por Ressonância Magnética , Descanso
19.
Depress Anxiety ; 38(8): 836-845, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34157177

RESUMO

BACKGROUND: Based on findings from adults with obsessive-compulsive disorder (OCD), this study examined alterations in resting-state functional connectivity (rs-fc) between the basolateral amygdala (BLA) and the ventromedial prefrontal cortex (vmPFC) in children and adolescents with OCD. We also assessed whether such BLA-vmPFC connectivity changed with or predicted response to exposure and response prevention (E/RP), the first-line treatment for pediatric OCD, given the involvement of these regions in fear processing, regulation, and extinction learning-a probable mechanism of action of E/RP. METHODS: Resting state functional magnetic resonance imaging scans were acquired from 25 unmedicated, treatment-naïve pediatric patients with OCD (12.8 ± 2.9 years) and 23 age- and sex-matched healthy controls (HCs; 11.0 ± 3.3 years). Patients completed a 12-16-week E/RP intervention for OCD. Participants were rescanned after the 12-16-week period. ANCOVAs tested group differences in baseline rs-fc. Cross-lagged panel models examined relationships between BLA-vmPFC rs-fc and OCD symptoms pre- and posttreatment. All tests were adjusted for participants' age, sex, and head motion. RESULTS: Right BLA-vmPFC rs-fc was significantly reduced (more negative) in patients with OCD relative to HCs at baseline, and increased following treatment. In patients, more positive (less negative) right BLA-vmPFC rs-fc pretreatment predicted greater OCD symptoms reduction posttreatment. Changes in BLA-vmPFC rs-fc was unassociated with change in OCD symptoms pre- to posttreatment. CONCLUSIONS: These results provide further evidence of the BLA-vmPFC pathway as a potential target for novel treatments or prevention strategies aimed at facilitating adaptive learning and fear extinction in children with OCD or subclinical OCD symptoms.


Assuntos
Terapia Cognitivo-Comportamental , Transtorno Obsessivo-Compulsivo , Adolescente , Adulto , Mapeamento Encefálico , Criança , Extinção Psicológica , Medo , Humanos , Imageamento por Ressonância Magnética , Vias Neurais , Transtorno Obsessivo-Compulsivo/diagnóstico por imagem , Transtorno Obsessivo-Compulsivo/terapia , Descanso
20.
Artigo em Inglês | MEDLINE | ID: mdl-34069110

RESUMO

The aim of this study was to evaluate the acute and adaptive effects of passive extreme heat (100 ± 3 °C) exposition in combination with a strength training protocol on maximal isometric handgrip strength. Fifty-four untrained male university students participated in this investigation. Twenty-nine formed the control group (NG) and 25 the heat-exposed group (HG). All the participants performed a 3-week isotonic handgrip strength training program twice a week with a training volume of 10 series of 10 repetitions with 45-s rest between series, per session. All the subjects only trained their right hand, leaving their left hand untrained. HG performed the same training protocol in hot (100 ± 3 °C) conditions in a dry sauna. Maximal isometric handgrip strength was evaluated each training day before and after the session. NG participants did not experience any modifications in either hand by the end of the study while HG increased maximal strength values in both hands (p < 0.05), decreased the difference between hands (p < 0.05), and recorded higher values than the controls in the trained (p < 0.05) and untrained (p < 0.01) hands after the intervention period. These changes were not accompanied by any modification in body composition in either group. The performance of a unilateral isotonic handgrip strength program in hot conditions during the three weeks induced an increase in maximal isometric handgrip strength in both hands without modifications to bodyweight or absolute body composition.


Assuntos
Calor Extremo , Treinamento de Força , Mãos , Força da Mão , Humanos , Masculino , Músculo Esquelético , Descanso
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...