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1.
Am J Public Health ; 114(S3): S258-S267, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37948054

RESUMO

Objectives. To assess how personal social network characteristics moderated mental health declines during the COVID-19 pandemic in emerging adults compared with other age groups. Methods. The Person to Person Health Interview Study, a representative, probability-based cohort study (n = 2485) in Indiana, collected data through face-to-face (baseline) and phone (follow-up) interviews before and during the pandemic. We used survey-weighted growth curve models to examine network effects on computer-adaptive testing measures of depression and anxiety severity. Results. Respondents reported significantly increased depression and anxiety in 2021, which returned almost to baseline levels for most age groups by 2022 (P < .001). Stronger ties to others and more interconnected ties were significantly associated with lower depression (B = -0.112 [P < .05]; B = -0.086 [P < .001]) and anxiety (B = -0.101 [P < .05]; B = -0.063 [P < .01]) severity across the pandemic. Interaction models revealed disproportionate protective effects of network characteristics on depression (B = -0.456 [P < .001]; B = -0.268 [P < .001]) and anxiety (B = -0.388 [P < .001]; B = -0.284 [P < .001]) for emerging adults. Conclusions. Cohesive and affectively strong personal networks promote resiliency to common mental health challenges during periods of crisis, particularly for emerging adults whose social roles and relationships were disrupted during a critical period of development. (Am J Public Health. 2024;114(S3):S258-S267. https://doi.org/10.2105/AJPH.2023.307426).


Assuntos
COVID-19 , Resiliência Psicológica , Adulto , Humanos , COVID-19/epidemiologia , Estudos de Coortes , Saúde Mental , Pandemias , Ansiedade/epidemiologia , Rede Social , Depressão/epidemiologia
2.
J Sports Sci ; 41(12): 1207-1217, 2023 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-37789670

RESUMO

This study compared the effects of supervised versus unsupervised resistance training (RT) on measures of muscle strength and hypertrophy in resistance-trained individuals. Thirty-six young men and women were randomly assigned to one of two experimental, parallel groups to complete an 8-week RT programme: One group received direct supervision for their RT sessions (SUP); the other group performed the same RT programme in an unsupervised manner (UNSUP). Programme variables were kept constant between groups. We obtained pre- and post-study assessments of body composition via multi-frequency bioelectrical impedance analysis (MF-BIA), muscle thickness of the upper and lower limbs via ultrasound, 1 repetition maximum (RM) in the back squat and bench press, isometric knee extension strength, and countermovement jump (CMJ) height. Results showed the SUP group generally achieved larger increases in muscle thickness for the triceps brachii, all sites of the rectus femoris, and the proximal region of the vastus lateralis. MF-BIA indicated increases in lean mass favoured SUP. Squat 1RM was greater for SUP; bench press 1RM and isometric knee extension were similar between conditions. CMJ increases modestly favoured UNSUP. In conclusion, our findings suggest that supervised RT promotes greater muscular adaptations and enhances exercise adherence in young, resistance-trained individuals.


Assuntos
Treinamento Resistido , Masculino , Humanos , Feminino , Treinamento Resistido/métodos , Músculo Quadríceps/fisiologia , Músculo Esquelético/fisiologia , Extremidade Inferior , Braço , Força Muscular/fisiologia , Adaptação Fisiológica
3.
Alzheimers Dement ; 19(6): 2655-2665, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-37037592

RESUMO

Individuals with more complex jobs experience better cognitive function in old age and a lower risk of dementia, yet complexity has multiple dimensions. Drawing on the Social Networks in Alzheimer Disease study, we examine the association between occupational complexity and cognition in a sample of older adults (N = 355). A standard deviation (SD) increase in complex work with people is associated with a 9% to 12% reduction in the probability of mild cognitive impairment or dementia, a 0.14-0.19 SD increase in episodic memory, and a 0.18-0.25 SD increase in brain reserve, defined as the gap (residual) between global cognitive function and magnetic resonance imaging (MRI) indicators of brain atrophy. In contrast, complexity with data or things is rarely associated with cognitive outcomes. We discuss the clinical and methodological implications of these findings, including the need to complement data-centered activities (e.g., Sudoku puzzles) with person-centered interventions that increase social complexity.


Assuntos
Envelhecimento Cognitivo , Reserva Cognitiva , Demência , Memória Episódica , Carga de Trabalho , Idoso , Feminino , Humanos , Masculino , Atrofia , Encéfalo/diagnóstico por imagem , Encéfalo/patologia , Disfunção Cognitiva/epidemiologia , Disfunção Cognitiva/prevenção & controle , Demência/epidemiologia , Demência/prevenção & controle , Satisfação no Emprego , Fatores Sociais , Interação Social , Carga de Trabalho/psicologia
4.
J Strength Cond Res ; 37(7): 1350-1357, 2023 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-37347940

RESUMO

ABSTRACT: Rosa, A, Coleman, M, Haun, C, Grgic, J, and Schoenfeld, BJ. Repetition performance, rating of perceived discomfort, and blood lactate responses to different rest interval lengths in single-joint and multijoint lower-body exercise. J Strength Cond Res 37(7): 1350-1357, 2023-The purpose of this study was to examine the effects of different rest interval lengths (RILs) on repetition performance, rating of discomfort, and blood lactate responses during lower-body single-joint and multijoint exercises. This study used a counterbalanced design where each subject performed the Smith machine back squat (BS) and leg extension (LE) using 3 different RIL configurations (1, 2, and 3 minutes) in a randomized fashion. Data collection occurred over the span of 3 separate days. Volunteers were randomly allocated to perform the independent variables (RILs and exercises) in 1 of 12 potential configurations. The initial session was allotted for familiarization with the rating of discomfort scale and 10 repetition maximum testing. The other 2 sessions involved training with the different configurations of RIL length using both the BS and LE. Randomization ensured that the BS was performed first in one of the training sessions and the LE was performed first in the other session. Results indicated that longer RILs had a small positive effect on repetition performance, with longer rest durations allowing for more repetitions compared with shorter durations. The largest difference in repetition performance between RILs was observed between 1 minute and 2-3 minutes rest; there were trivial differences in repetition performance between 2 and 3 minutes rest for both the BS and LE. Blood lactate levels were slightly higher with longer RILs. Overall, BS showed greater increases in blood lactate compared with LE, and these differences were magnified over time. Exercise selection and RIL both influenced rating of discomfort, with LE producing less discomfort than BS and longer RILs reducing perceived discomfort. Our findings suggest that RIL influences the repetition performance, blood lactate, and rating of discomfort responses between single-joint and multijoint exercises.


Assuntos
Treinamento Resistido , Humanos , Exercício Físico/fisiologia , Terapia por Exercício , Lactatos , Músculo Esquelético/fisiologia , Treinamento Resistido/métodos , Descanso/fisiologia
5.
Soc Networks ; 70: 393-402, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35665241

RESUMO

When the coronavirus emerged in early 2020, older adults were at heightened risk of contracting the virus, and of suffering mental health consequences from the pandemic and from the precautions designed to mitigate it. In this paper, we examine how social networks prior to the pandemic helped to shape health beliefs, behaviors, and outcomes among older adults during its onset, focusing on (1) perceived risk of COVID-19, (2) preventative health behaviors, and (3) mental health, including loneliness, perceived stress, depression, and anxiety. Drawing on the longitudinal Social Networks in Alzheimer Disease study, we find that networks high in bridging social capital predict greater perceived risk and more precautions taken, but worse mental health. In contrast, networks high in bonding social capital predict less perceived risk and fewer precautions taken, but better mental health. We discuss this apparent tradeoff between physical and mental health.

6.
Alzheimers Dement ; 18(5): 934-941, 2022 05.
Artigo em Inglês | MEDLINE | ID: mdl-34482619

RESUMO

Research suggests social connectedness may help older adults with dementia maintain cognitive functionality and quality of life. However, little is known about its specific social and biological mechanisms. This paper proposes two pathways through social bridging (i.e., cognitive enrichment through expansive social networks) and bonding (i.e., neuroendocrine benefits of integration in cohesive social networks). We provide preliminary evidence for these pathways using neuroimaging, cognitive, and egocentric social network data from the Social Networks and Alzheimer's Disease (SNAD) study (N = 280). We found that network size, density, and presence of weak ties (i.e., social bridging) moderated the association between brain atrophy and cognitive function, while marriage/cohabitation (i.e., social bonding) moderated the association between perceived stress and cognitive function. We argue that social connectedness may have downstream implications for multiple pathophysiological processes in cognitive aging, even negating existing structural damage to the brain, making it a strong candidate for clinical or policy intervention.


Assuntos
Doença de Alzheimer , Qualidade de Vida , Adolescente , Idoso , Encéfalo/diagnóstico por imagem , Cognição , Humanos , Rede Social
7.
Soc Networks ; 64: 99-108, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32952277

RESUMO

Although it is widely accepted that personal networks influence health and illness, network recall remains a major concern. This concern is heightened when studying a population that is vulnerable to cognitive decline. Given these issues, we use data from the Social Network in Alzheimer Disease project to explore similarities and discrepancies between the network perceptions of focal participants and study partners. By leveraging data on a sample of older adults with normal cognition, mild cognitive impairment, and early stage dementia, we explore how cognitive impairment influences older adults' perceptions of their personal networks. We find that the average individual is more likely to omit weaker, peripheral ties from their self-reported networks than stronger, central ties. Despite observing only moderate levels of focal-partner corroboration across our sample, we find minimal evidence of perceptual differences across diagnostic groups. We offer two broad conclusions. First, self-reported network data, though imperfect, offer a reasonable account of the core people in one's life. Second, our findings assuage concerns that cognitively impaired older adults have skewed perceptions of their personal networks.

8.
Philos Trans A Math Phys Eng Sci ; 377(2137)2018 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-30530535

RESUMO

Carbon capture and storage is a transition technology from a past and present fuelled by coal, oil and gas and a planned future dominated by renewable energy sources. The technology involves the capture of carbon dioxide emissions from fossil fuel power stations and other point sources, compression of the CO2 into a fluid, transporting it and injecting it deep beneath the Earth's surface into depleted petroleum reservoirs and other porous formations. Once injected, the CO2 must be monitored to ensure that it is emplaced and assimilated as planned and that none leaks back to surface. A variety of methods have been deployed to monitor the CO2 storage site and many such methods have been adapted from oilfield practice. However, such methods are commonly indirect, episodic, require active signal generation and remain expensive throughout the monitoring period that may last for hundreds of years. A modelling framework was developed to concurrently simulate CO2 geostorage conditions and background cosmic-ray muon tomography, in which the potential was assessed for using variations in muon attenuation, due to changes in CO2 abundance, as a means of CO2 detection. From this, we developed a passive, continuous monitoring method for CO2 storage sites using muon tomography, the tools for which can be deployed during the active drilling phase (development) of the storage site. To do this, it was necessary to develop a muon detector that could be used in the hostile environment (saline, high temperature) of the well bore. A prototype detector has been built and tested at the 1.1 km deep Boulby potash mine on the northeast coast of England, supported by the existing STFC Boulby Underground Laboratory on the site. The detector is now ready to be commercialized.This article is part of the Theo Murphy meeting issue 'Cosmic-ray muography'.

9.
Anal Chem ; 88(7): 3891-8, 2016 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-26898343

RESUMO

We describe a novel method for measuring stable bromine isotope compositions in saline solutions such as seawater, brines, and formation waters. Bromine is extracted from the samples by ion exchange chromatography on anion exchange resin AG 1-X4 with NH4NO3 and measured by MC-ICP-MS in wet plasma conditions. Sample introduction through a small spray chamber provided good sensitivity and stability of the Br signal compared to direct injection (d-DIHEN) and desolvation (APEX). NH4NO3 media allowed fast (<3 min) washing of the system. Despite Ar2H(+) spectral interference on (81)Br(+), for the first time low-resolution mode (with appropriate tuning of Ar2H(+)/(81)Br(+) sensitivity) gave higher precision (81)Br/(79)Br measurements than high-resolution (HR), due to the narrowness of the (81)Br(+) plateau in HR mode and to slight mass drifting with time. Additionally, 1 µg Br is the lower amount needed for a triplicate determination of δ(81)Br by MC-ICP-MS, with reproducibility often < ± 0.1‰ (2 SD). Four HBr solutions were prepared by evaporation/condensation in order to obtain in-house reference solutions with 3‰ variations in δ(81)Br and to assess the reproducibility and accuracy of the method. Long-term (>3 years) reproducibility between ± 0.11 and ± 0.27‰ (2 SD) was obtained for the four HBr solutions, the international standard reference material NIST SRM 977 (δ(81)BrSMOB = -0.65 ± 1.1‰, 1 SD), and seawaters (synthetic and natural). The accuracy of the MC-ICP-MS method was validated by comparing the δ(81)Br obtained for these solutions with dual-inlet IRMS measurements on CH3Br gas. Finally, the method was successfully applied to 22 natural samples.

10.
Sci Justice ; 64(3): 251-257, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38735659

RESUMO

A new method for looking for life outside the Earth is used as an example to demonstrate how ways of presenting complex scientific concepts to the general public, used in planetary science, could be used in forensic science. The work led to a pared down, practical definition of detectable Life for planetary exploration, An organised system capable of processing energy sources to its advantage. For nearly three quarters of Earth's history the only lifeforms were microbes, which are the target for looking for extraterrestrial life. Microbes are microscopic and may be sparsely distributed, but their metabolic products can form large, durable rocks, much easier to find and which may contain the organisms or their remains. There are similar challenges in presenting astrobiological and forensic science. Both may have to deal with very large or very small numbers which are not immediately comprehensible but can be understood by analogy. To increase the impact on the listener or reader, dramatic analogues are valuable, for example, referring to the mineralised microbial metabolic products as, "fossilised breath of bacteria" demands the audience's attention and engages them before more detailed explanations are given. The power of practical experiments or demonstrations is most important to reinforce what might otherwise be a fairly abstract concept. Surprisingly, most of these approaches can be made to work equally well in both spoken and written forms as well as in both sciences.


Assuntos
Exobiologia , Ciências Forenses , Marte , Ciências Forenses/métodos , Humanos , Bactérias/isolamento & purificação , Meio Ambiente Extraterreno
11.
J Health Soc Behav ; 65(1): 94-109, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37864410

RESUMO

Republicans and conservatives report better self-rated health and well-being compared to Democrats and liberals, yet they are more likely to reside in geographic areas with heavy COVID-19 morbidity and mortality. This harmed health on "both sides" of political divides, occurring in a time of rapid sociopolitical upheaval, warrants the revisiting of psychosocial mechanisms linked to political health differences. Drawing on national Gallup data (early 2021), we find that predicted differences in health or well-being vary substantially by ideology, party, voting behavior, and policy beliefs, with model fit depending on how politics are measured. Differences in self-rated health, psychological distress, happiness, trouble sleeping, and delayed health care tend to reveal worse outcomes for Democrats or liberals. Such differences often are reduced to insignificance by some combination of mastery, meritocratic beliefs, perceived social support, and COVID-19-related exposures and attitudes. Policy beliefs predict health differences most robustly across outcomes and mechanism adjustments.


Assuntos
COVID-19 , Pandemias , Humanos , Felicidade , Política , Votação
12.
PeerJ ; 12: e16777, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38274324

RESUMO

Background: Based on emerging evidence that brief periods of cessation from resistance training (RT) may re-sensitize muscle to anabolic stimuli, we aimed to investigate the effects of a 1-week deload interval at the midpoint of a 9-week RT program on muscular adaptations in resistance-trained individuals. Methods: Thirty-nine young men (n = 29) and women (n = 10) were randomly assigned to 1 of 2 experimental, parallel groups: An experimental group that abstained from RT for 1 week at the midpoint of a 9-week, high-volume RT program (DELOAD) or a traditional training group that performed the same RT program continuously over the study period (TRAD). The lower body routines were directly supervised by the research staff while upper body training was carried out in an unsupervised fashion. Muscle growth outcomes included assessments of muscle thickness along proximal, mid and distal regions of the middle and lateral quadriceps femoris as well as the mid-region of the triceps surae. Adaptions in lower body isometric and dynamic strength, local muscular endurance of the quadriceps, and lower body muscle power were also assessed. Results: Results indicated no appreciable differences in increases of lower body muscle size, local endurance, and power between groups. Alternatively, TRAD showed greater improvements in both isometric and dynamic lower body strength compared to DELOAD. Additionally, TRAD showed some slight psychological benefits as assessed by the readiness to train questionnaire over DELOAD. Conclusion: In conclusion, our findings suggest that a 1-week deload period at the midpoint of a 9-week RT program appears to negatively influence measures of lower body muscle strength but has no effect on lower body hypertrophy, power or local muscular endurance.


Assuntos
Treinamento Resistido , Masculino , Humanos , Feminino , Treinamento Resistido/métodos , Músculo Esquelético/fisiologia , Músculo Quadríceps/fisiologia , Força Muscular/fisiologia , Adaptação Fisiológica
13.
Psychol Addict Behav ; 37(6): 734-745, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37668564

RESUMO

OBJECTIVE: People with substance use disorders (SUDs) are faced with pervasive stigma. Education-based interventions tend to emphasize biological causes of dependency; however, health care professionals still stigmatize people who use substances despite being more knowledgeable about biological causes. There may be an important moderating role of personal contact since health care professionals may treat people in the throes of dependency. METHOD: We tested how substance use stigma may be explained by causal attributions, working in health care, and personal contact. A nationally representative sample of the U.S. general population (N = 6,812) was collected with targeted oversampling of health care professionals (N = 788). Using a vignette paradigm, desire for social distance was measured along with causal attributions and contact. RESULTS: Health care professionals were no less stigmatizing than the general population. However, attributing substance dependency to bad character was robustly associated with stigma, but these beliefs were moderated by the interaction between working in health care and contact. Mediation decomposition confirmed that contact transmitted its effect by lowering bad character attributions, and this mediation was significantly stronger for health care professionals. CONCLUSIONS: Health care professionals and the general population may hold similar levels of stigma when accounting for attributions, and personal contact plays an important role. We discuss the implications of these results for stigma-reduction campaigns and emphasize deconstructing personal culpability narratives surrounding substance use disorders. (PsycInfo Database Record (c) 2023 APA, all rights reserved).


Assuntos
Percepção Social , Transtornos Relacionados ao Uso de Substâncias , Humanos , Pessoal de Saúde
14.
Sports Med Open ; 9(1): 87, 2023 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-37730925

RESUMO

BACKGROUND: Deloading is a ubiquitous yet under-researched strategy within strength and physique training. How deloading should be integrated into the training programme to elicit optimal training outcomes is unknown. To aid its potential integration, this study established consensus around design principles for integrating deloading in strength and physique training programmes using expert opinion and practical experience. METHODS: Expert strength and physique coaches were invited to an online Delphi consisting of 3 rounds. Thirty-four coaches completed the first round, 29 completed the second round, and 21 completed the third round of a Delphi questionnaire. In the first round, coaches answered 15 open-ended questions from four categories: 1: General Perceptions of Deloading; 2: Potential Applications of Deloading; 3: Designing and Implementing Deloading; and 4: Creating an Inclusive Deloading Training Environment. First-round responses were analyzed using reflexive thematic analysis, resulting in 138 statements organized into four domains. In the second and third rounds, coaches rated each statement using a four-point Likert scale, and collective agreement or disagreement was calculated. RESULTS: Stability of consensus was achieved across specific aspects of the four categories. Findings from the final round were used to develop the design principles, which reflect the consensus achieved. CONCLUSIONS: This study develops consensus on design principles for integrating deloading into strength and physique sports training programmes. A consensus definition is proposed: "Deloading is a period of reduced training stress designed to mitigate physiological and psychological fatigue, promote recovery, and enhance preparedness for subsequent training." These findings contribute novel knowledge that might advance the current understanding of deloading in strength and physique sports.

15.
J Funct Morphol Kinesiol ; 8(2)2023 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-37218848

RESUMO

Emerging evidence indicates that the use of low-load resistance training in combination with blood flow restriction (LL-BFR) can be an effective method to elicit increases in muscle size, with most research showing similar whole muscle development of the extremities compared to high-load (HL) training. It is conceivable that properties unique to LL-BFR such as greater ischemia, reperfusion, and metabolite accumulation may enhance the stress on type I fibers during training compared to the use of LLs without occlusion. Accordingly, the purpose of this paper was to systematically review the relevant literature on the fiber-type-specific response to LL-BFR and provide insights into future directions for research. A total of 11 studies met inclusion criteria. Results of the review suggest that the magnitude of type I fiber hypertrophy is at least as great, and sometimes greater, than type II hypertrophy when performing LL-BFR. This finding is in contrast to HL training, where the magnitude of type II fiber hypertrophy tends to be substantially greater than that of type I myofibers. However, limited data directly compare training with LL-BFR to nonoccluded LL or HL conditions, thus precluding the ability to draw strong inferences as to whether the absolute magnitude of type I hypertrophy is indeed greater in LL-BFR vs. traditional HL training. Moreover, it remains unclear as to whether combining LL-BFR with traditional HL training may enhance whole muscle hypertrophy via greater increases in type I myofiber cross-sectional area.

16.
J Funct Morphol Kinesiol ; 9(1)2023 Dec 29.
Artigo em Inglês | MEDLINE | ID: mdl-38249086

RESUMO

Regimented resistance training (RT) has been shown to promote increases in muscle size. When engaging in RT, practitioners often emphasize the importance of appropriate exercise technique, especially when trying to maximize training adaptations (e.g., hypertrophy). This narrative review aims to synthesize existing evidence on what constitutes proper RT exercise technique for maximizing muscle hypertrophy, focusing on variables such as exercise-specific kinematics, contraction type, repetition tempo, and range of motion (ROM). We recommend that when trying to maximize hypertrophy, one should employ a ROM that emphasizes training at long muscle lengths while also employing a repetition tempo between 2 and 8 s. More research is needed to determine whether manipulating the duration of either the eccentric or concentric phase further enhances hypertrophy. Guidelines for body positioning and movement patterns are generally based on implied theory from applied anatomy and biomechanics. However, existing research on the impact of manipulating these aspects of exercise technique and their effect on hypertrophy is limited; it is therefore suggested that universal exercise-specific kinematic guidelines are followed and adopted in accordance with the above recommendations. Future research should investigate the impact of stricter versus more lenient exercise technique variations on hypertrophy.

17.
Sci Rep ; 13(1): 8212, 2023 05 22.
Artigo em Inglês | MEDLINE | ID: mdl-37217559

RESUMO

The purpose of this study was to compare the effects of electromagnetic resistance alone, as well as in combination with variable resistance or accentuated eccentric methods, with traditional dynamic constant external resistance exercise on myoelectric activity during elbow flexion. The study employed a within-participant randomized, cross-over design whereby 16 young, resistance-trained male and female volunteers performed elbow flexion exercise under each of the following conditions: using a dumbbell (DB); using a commercial electromagnetic resistance device (ELECTRO); variable resistance (VR) using a setting on the device that attempts to match the level of resistance to the human strength curve, and; eccentric overload (EO) using a setting on the device that increases the load by 50% on the eccentric portion of each repetition. Surface electromyography (sEMG) was obtained for the biceps brachii, brachioradialis and anterior deltoid on each of the conditions. Participants performed the conditions at their predetermined 10 repetition maximum. " The order of performance for the conditions was counterbalanced, with trials separated by a 10-min recovery period. The sEMG was synced to a motion capture system to assess sEMG amplitude at elbow joint angles of 30°, 50°, 70°, 90°, 110°, with amplitude normalized to the maximal activation. The anterior deltoid showed the largest differences in amplitude between conditions, where median estimates indicated greater concentric sEMG amplitude (~ 7-10%) with EO, ELECTRO and VR compared with DB. Concentric biceps brachii sEMG amplitude was similar between conditions. In contrast, results indicated a greater eccentric amplitude with DB compared to ELECTRO and VR, but unlikely to exceed a 5% difference. Data indicated a greater concentric and eccentric brachioradialis sEMG amplitude with DB compared to all other conditions, but differences were unlikely to exceed 5%. The electromagnetic device tended to produce greater amplitudes in the anterior deltoid, while DB tended to produce greater amplitudes in the brachioradialis; amplitude for the biceps brachii was relatively similar between conditions. Overall, any observed differences were relatively modest, equating to magnitudes of ~ 5% and not likely greater than 10%. These differences would seem to be of minimal practical significance.


Assuntos
Eletromiografia , Músculo Esquelético , Treinamento Resistido , Estudos Cross-Over , Humanos , Masculino , Feminino , Músculo Esquelético/fisiologia , Cotovelo/fisiologia , Braço/fisiologia , Contração Muscular , Adulto Jovem , Adulto
18.
J Funct Morphol Kinesiol ; 8(2)2023 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-37218855

RESUMO

The present paper aimed to systematically review case studies on physique athletes to evaluate longitudinal changes in measures of body composition, neuromuscular performance, chronic hormonal levels, physiological adaptations, and psychometric outcomes during pre-contest preparation. We included studies that (1) were classified as case studies involving physique athletes during the pre-contest phase of their competitive cycle; (2) involved adults (18+ years of age) as participants; (3) were published in an English-language peer-reviewed journal; (4) had a pre-contest duration of at least 3 months; (5) reported changes across contest preparation relating to measures of body composition (fat mass, lean mass, and bone mineral density), neuromuscular performance (strength and power), chronic hormonal levels (testosterone, estrogen, cortisol, leptin, and ghrelin), physiological adaptations (maximal aerobic capacity, resting energy expenditure, heart rate, blood pressure, menstrual function, and sleep quality), and/or psychometric outcomes (mood states and food desire). Our review ultimately included 11 case studies comprising 15 ostensibly drug-free athletes (male = 8, female = 7) who competed in various physique-oriented divisions including bodybuilding, figure, and bikini. The results indicated marked alterations across the array of analyzed outcomes, sometimes with high inter-individual variability and divergent sex-specific responses. The complexities and implications of these findings are discussed herein.

19.
Nutrients ; 15(9)2023 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-37432300

RESUMO

The purpose of this paper was to carry out a systematic review with a meta-analysis of randomized controlled trials that examined the combined effects of resistance training (RT) and creatine supplementation on regional changes in muscle mass, with direct imaging measures of hypertrophy. Moreover, we performed regression analyses to determine the potential influence of covariates. We included trials that had a duration of at least 6 weeks and examined the combined effects of creatine supplementation and RT on site-specific direct measures of hypertrophy (magnetic resonance imaging (MRI), computed tomography (CT), or ultrasound) in healthy adults. A total of 44 outcomes were analyzed across 10 studies that met the inclusion criteria. A univariate analysis of all the standardized outcomes showed a pooled mean estimate of 0.11 (95% Credible Interval (CrI): -0.02 to 0.25), providing evidence for a very small effect favoring creatine supplementation when combined with RT compared to RT and a placebo. Multivariate analyses found similar small benefits for the combination of creatine supplementation and RT on changes in the upper and lower body muscle thickness (0.10-0.16 cm). Analyses of the moderating effects indicated a small superior benefit for creatine supplementation in younger compared to older adults (0.17 (95%CrI: -0.09 to 0.45)). In conclusion, the results suggest that creatine supplementation combined with RT promotes a small increase in the direct measures of skeletal muscle hypertrophy in both the upper and lower body.


Assuntos
Creatina , Treinamento Resistido , Humanos , Idoso , Hipertrofia , Músculos , Suplementos Nutricionais
20.
Proc Natl Acad Sci U S A ; 106(24): 9548-55, 2009 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-19515817

RESUMO

The approximately 3,450-million-year-old Strelley Pool Formation in Western Australia contains a reef-like assembly of laminated sedimentary accretion structures (stromatolites) that have macroscale characteristics suggestive of biological influence. However, direct microscale evidence of biology--namely, organic microbial remains or biosedimentary fabrics--has to date eluded discovery in the extensively-recrystallized rocks. Recently-identified outcrops with relatively good textural preservation record microscale evidence of primary sedimentary processes, including some that indicate probable microbial mat formation. Furthermore, we find relict fabrics and organic layers that covary with stromatolite morphology, linking morphologic diversity to changes in sedimentation, seafloor mineral precipitation, and inferred microbial mat development. Thus, the most direct and compelling signatures of life in the Strelley Pool Formation are those observed at the microscopic scale. By examining spatiotemporal changes in microscale characteristics it is possible not only to recognize the presence of probable microbial mats during stromatolite development, but also to infer aspects of the biological inputs to stromatolite morphogenesis. The persistence of an inferred biological signal through changing environmental circumstances and stromatolite types indicates that benthic microbial populations adapted to shifting environmental conditions in early oceans.


Assuntos
Biodiversidade , Evolução Biológica , Biologia Marinha , Paleontologia , Animais , Austrália Ocidental
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