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Sports Medicine (Auckland, N.Z.) Jan 2021In accordance with the principle of training specificity, adaptations to vertically or horizontally orientated plyometric training (VPT, HPT) directly transfer to... (Meta-Analysis)
Meta-Analysis
BACKGROUND
In accordance with the principle of training specificity, adaptations to vertically or horizontally orientated plyometric training (VPT, HPT) directly transfer to athletic tasks that are carried out in the same direction as they are performed.
OBJECTIVES
The objective of this systematic review and meta-analysis was to determine the relative effect of VPT and HPT on both vertical and horizontal measures of physical performance.
DATA SOURCES
Google Scholar, CrossRef, Microsoft Academic, PubMed, Web of Science, Scopus.
STUDY ELIGIBILITY CRITERIA
To qualify for inclusion in the meta-analysis, studies must have included a plyometric training intervention that compared jumps executed in a vertical direction [i.e. countermovement jump (CMJ)] to jumps executed in a horizontal direction (i.e. standing horizontal jump).
STUDY APPRAISAL AND SYNTHESIS METHODS
We used the inverse-variance random effects model for meta-analyses. Effect sizes, calculated from measures of horizontally or vertically orientated performance, were represented by the standardised mean difference and presented alongside 95% confidence intervals (CI).
RESULTS
For between-group analysis on horizontal outcomes, there was a moderate, significant effect size (ES) in favour of HPT (0.65 [95% CI 0.12, 1.18], Z = 2.41 [p = 0.02]). For the analysis on vertical outcomes, there was a trivial, non-significant difference between VPT and HPT (- 0.04 [95% CI - 0.33, 0.24], Z = 0.0.29 [p = 0.77]). Within-group analysis showed HPT to be superior to VPT across horizontally- (1.05 [0.38, 1.72] vs. 0.84 [0.37, 1.31]) and vertically-orientated (0.74 [0.08, 1.40] vs. 0.72 [0.02, 1.43]) performance measures. For horizontally-orientated outcomes, single-factor moderator analyses showed that longer programmes (> 7 weeks), more sessions (> 12) and combined bilateral and unilateral training were most effective, favouring HPT in each case. In vertically orientated outcomes, these same variables showed only trivial differences between HBT and VBT.
CONCLUSIONS
HPT is at least as effective as VPT at enhancing vertical performance but is superior at enhancing horizontal performance. This means that HPT might be a more efficient method for enhancing multi-vector performance for sport.
Topics: Acclimatization; Athletic Performance; Humans; Muscle Strength; Plyometric Exercise; Soccer
PubMed: 32897526
DOI: 10.1007/s40279-020-01340-6 -
Frontiers in Plant Science 2020Plants are key to the functionality of many ecosystem processes. The duration and intensity of water stress are anticipated to increase in the future; however, a...
Plants are key to the functionality of many ecosystem processes. The duration and intensity of water stress are anticipated to increase in the future; however, a detailed elucidation of the responses of plants to water stress remains incomplete. For this study, we present a meta-analysis derived from the 1,301 paired observations of 84 studies to evaluate the responses of plants to water stress. The results revealed that although water stress inhibited plant growth and photosynthesis, it increased reactive oxygen species (ROS), plasma membrane permeability, enzymatic antioxidants, and non-enzymatic antioxidants. Importantly, these responses generally increased with the intensity and duration of water stress, with a more pronounced decrease in ROS anticipated over time. Our findings suggested that the overproduction of ROS was the primary mechanism behind the responses of plants to water stress, where plants appeared to acclimatize to water stress, to some extent, over time. Our synthesis provides a framework for better understanding the responses and mechanisms of plants under drought conditions.
PubMed: 32676096
DOI: 10.3389/fpls.2020.00978 -
International Journal of Environmental... Apr 2020The current systematic review evaluated the effects of different pre-cooling techniques on sports performance in highly-trained athletes under high temperature...
The current systematic review evaluated the effects of different pre-cooling techniques on sports performance in highly-trained athletes under high temperature conditions. PubMed/MEDLINE, EMBASE, Web of Science, CENTRAL, Scopus, and SPORTDiscus databases were searched from inception to December 2019. Studies performing pre-cooling interventions in non-acclimatized highly-trained athletes (>55 mL/kg/min of maximal oxygen consumption) under heat conditions (≥30 °C) were included. The searched reported 26 articles. Pre-cooling techniques can be external (exposure to ice water, cold packs, or cooling clothes), internal (intake of cold water or ice), or mixed. Cooling prior to exercise concluded increases in distance covered (1.5-13.1%), mean power output (0.9-6.9%), time to exhaustion (19-31.9%), work (0.1-8.5%), and mean peak torque (10.4-22.6%), as well as reductions in completion time (0.6-6.5%). Mixed strategies followed by cold water immersion seem to be the most effective techniques, being directly related with the duration of cooling and showing the major effects in prolonged exercise protocols. The present review showed that pre-cooling methods are an effective strategy to increase sports performance in hot environments. This improvement is associated with the body surface exposed and its sensibility, as well as the time of application, obtaining the best results in prolonged physical exercise protocols.
Topics: Athletes; Athletic Performance; Body Temperature; Body Temperature Regulation; Cold Temperature; Hot Temperature; Humans
PubMed: 32344616
DOI: 10.3390/ijerph17082952 -
BMJ Open Apr 2020This review aimed to describe the epidemiology of all heat-related illnesses in women compared with men in the armed forces and to identify gender-specific risk factors...
OBJECTIVES
This review aimed to describe the epidemiology of all heat-related illnesses in women compared with men in the armed forces and to identify gender-specific risk factors and differences in heat tolerance.
DESIGN
A systematic review of multiple databases (MEDLINE, Emcare, CINAHL, PsycINFO, Informit and Scopus) was conducted from the inception of the databases to 1 April 2019 using the preferred reporting items for systematic review and meta-analysis guidelines.
ELIGIBILITY CRITERIA
All relevant studies investigating and comparing heat illness and heat tolerance in women and men in the armed forces were included in the review.
RESULTS
Twenty-four studies were included in the systematic review. The incidence of heat stroke in women ranged from 0.10 to 0.26 per 1000 person-years, while the incidence of heat stroke ranged from 0.22 to 0.48 per 1000 person-years in men. The incidence of other heat illnesses in women compared with men ranged from 1.30 to 2.89 per 1000 person-years versus 0.98 to 1.98 per 1000 person-years. The limited evidence suggests that women had a greater risk of exertional heat illness compared with men. Other gender-specific risk factors were slower run times and body mass index. Although there was a higher proportion of women who were heat intolerant compared with men, this finding needs to be interpreted with caution due to the limited evidence.
CONCLUSION
The findings of this review suggest that men experienced a slightly higher incidence of heat stroke than women in the armed forces. In addition, the limited available evidence suggests that a higher proportion of women were heat intolerant and being a female was associated with a greater risk of exertional heat illnesses. Given the limited evidence available, further research is required to investigate the influence of gender differences on heat intolerance and heat illness.
Topics: Female; Heat Stress Disorders; Heat Stroke; Humans; Incidence; Male; Military Personnel; Risk Factors; Sex Distribution; Sex Factors; Thermotolerance
PubMed: 32265238
DOI: 10.1136/bmjopen-2019-031825 -
Indoor Air May 2020This paper presents a review on thermal comfort research that is informed by changes in occupant behavior, lifestyle, and income leading to rebound or pre-bound effect....
This paper presents a review on thermal comfort research that is informed by changes in occupant behavior, lifestyle, and income leading to rebound or pre-bound effect. It explores the current state of research in thermal comfort domain through a systematic review to identify the gaps and opportunities specifically focusing on energy-intensive developing countries. This review argues that adaptive thermal comfort is a continuously evolving domain owing to dynamic modifications in occupant behavior occurring from changes in the cost of energy services and preference of comfort (rebound/pre-bound effect). A conceptual framework linking thermal comfort, rebound/pre-bound effect, and occupant behavior is forwarded through the introduction of an exogenous factor related to occupant well-being. The results ascertain that there is a need of localized thermal comfort model with an occupant-centric approach that can help in enhancing comfort and reducing energy consumption.
Topics: Acclimatization; Air Pollution, Indoor; Humans; Temperature
PubMed: 32149411
DOI: 10.1111/ina.12664 -
Journal of Strength and Conditioning... May 2020Cormier, P, Freitas, TT, Rubio-Arias, JÁ, and Alcaraz, PE. Complex and contrast training: Does strength and power training sequence affect performance-based adaptations... (Meta-Analysis)
Meta-Analysis
Cormier, P, Freitas, TT, Rubio-Arias, JÁ, and Alcaraz, PE. Complex and contrast training: Does strength and power training sequence affect performance-based adaptations in team sports? A systematic review and meta-analysis. J Strength Cond Res 34(5): 1461-1479, 2020-The aims of this meta-analysis were to examine the effects of 2 different strength and power training sequences (complex: CPX; and contrast: CNT, training) on performance-based adaptations in team sports {lower-body strength (1 repetition maximum [1RM]), vertical jump (VJ), sprinting, and change of direction (COD) ability}, as well as identify factors potentially affecting said adaptations (i.e., athlete level, type of sport, intensity, and duration). CPX is the combination training that alternates biomechanically similar high load weight training exercises with lighter load power exercises, set for set (e.g., squats followed by countermovement jumps). CNT is the combination training where all high load strength exercises are performed at the beginning of the session and all lighter load power exercises at the end. After an electronic database search (PubMed, SPORTDiscus, and WoS), a total of 27 articles were included in the meta-analysis. The effects on outcomes were expressed as standardized mean differences (SMDs). Baseline to postintervention overall results for the studied variables: (a) 1RM: large effects for CPX (SMD = 2.01, 95% confidence interval [CI] 1.18-2.84) and CNT (SMD = 1.29, 95% CI 0.61-1.98); (b) VJ: large effects for CPX (SMD = 0.88, 95% CI 0.42-1.34) and medium effects for CNT (SMD = 0.55, 95% CI 0.29-0.81); (c) sprint: large effects for CPX (SMD = -0.94, 95% CI -1.33 to -0.54) and small effects for CNT (SMD = -0.27, 95% CI -0.92 to 0.39); and (d) COD: large effects for CPX (SMD = -1.17, 95% CI -1.43 to -0.90) and medium effects for CNT (SMD = -0.68, 95% CI -1.20 to -0.15). Regarding the studies that contained a control group: (a) 1RM: large effects for CPX (SMD = 1.61, 95% CI 1.12-2.10) and CNT (SMD = 1.38, 95% CI 0.30-2.46); (b) VJ: large effects for CPX (SMD = 0.85, 95% CI 0.45-1.25) and medium for CNT (SMD = 0.50, 95% CI 0.19-0.81); (c) sprint: medium effects for CPX (SMD = -0.69, 95% CI -1.02 to -0.36) and CNT (SMD = -0.51, 95% CI -0.90 to -0.11); and (d) COD: large effects for CPX (SMD = -0.83, 95% CI -1.08 to -0.59), and there were no control groups for CNT. In conclusion, both training interventions may lead to positive performance-based adaptations in team-sports with CPX interventions potentially leading to slightly greater effects.
Topics: Acclimatization; Adaptation, Physiological; Athletes; Athletic Performance; Humans; Muscle Strength; Resistance Training; Sports
PubMed: 32084104
DOI: 10.1519/JSC.0000000000003493 -
International Journal of Molecular... Nov 2019Several environmental factors, such as drought, salinity, and extreme temperatures, negatively affect plant growth and development, which leads to yield losses. The... (Comparative Study)
Comparative Study Meta-Analysis
Several environmental factors, such as drought, salinity, and extreme temperatures, negatively affect plant growth and development, which leads to yield losses. The tolerance or sensitivity to abiotic stressors are the expression of a complex machinery involving molecular, biochemical, and physiological mechanisms. Here, a meta-analysis on previously published RNA-Seq data was performed to identify the genes conferring tolerance to chilling, osmotic, and salt stresses, by comparing the transcriptomic changes between tolerant and susceptible rice genotypes. Several genes encoding transcription factors (TFs) were identified, suggesting that abiotic stress tolerance involves upstream regulatory pathways. A gene co-expression network defined the metabolic and signalling pathways with a prominent role in the differentiation between tolerance and susceptibility: (i) the regulation of endogenous abscisic acid (ABA) levels, through the modulation of genes that are related to its biosynthesis/catabolism, (ii) the signalling pathways mediated by ABA and jasmonic acid, (iii) the activity of the "Drought and Salt Tolerance" TF, involved in the negative regulation of stomatal closure, and (iv) the regulation of flavonoid biosynthesis by specific MYB TFs. The identified genes represent putative key players for conferring tolerance to a broad range of abiotic stresses in rice; a fine-tuning of their expression seems to be crucial for rice plants to cope with environmental cues.
Topics: Dehydration; Disease Resistance; Gene Expression Profiling; Gene Expression Regulation, Plant; Oryza; Osmoregulation; Plant Proteins; Salt Tolerance; Transcription Factors
PubMed: 31726733
DOI: 10.3390/ijms20225662 -
International Journal of Environmental... Nov 2019The population of older people is increasing at a rapid rate, with those 80 years and older set to triple by 2050. This systematic review aimed to examine older people's...
The population of older people is increasing at a rapid rate, with those 80 years and older set to triple by 2050. This systematic review aimed to examine older people's perceptions and behaviours against existing heatwaves prevention measures and systematically categorize and analyse those measures using the Ottawa charter for health promotion framework. Peer-reviewed published literature between 22nd September 2006 and 24th April 2018 was retrieved, according to the PRISMA guidelines, from five different databases. Eighteen articles were finally included. There is a lack of published studies from developing countries. Results were categorized and analysed using the Ottawa charter five action areas. Mitigation strategies from current heat action plans are discussed and gaps are highlighted. A lack of systematic evaluation of heat action plans efficacy was identified. Older people are not demonstrating all recommended preventative measures during heatwaves. Support personnel and health professionals are not being pro-active enough in facilitating prevention of adverse effects from heatwaves. Governments are beginning to implement policy changes, but other recommended support measures outlined in the Ottawa charter are still lacking, and hence require further action. Linkage between specific components of heat action plans and outcomes cannot be ascertained; therefore, more systematic evaluation is needed.
Topics: Acclimatization; Aged; Aged, 80 and over; Developing Countries; Health Promotion; Hot Temperature; Humans
PubMed: 31717424
DOI: 10.3390/ijerph16224370 -
Nature Communications Jul 2019Biological responses to climate change have been widely documented across taxa and regions, but it remains unclear whether species are maintaining a good match between... (Meta-Analysis)
Meta-Analysis
Biological responses to climate change have been widely documented across taxa and regions, but it remains unclear whether species are maintaining a good match between phenotype and environment, i.e. whether observed trait changes are adaptive. Here we reviewed 10,090 abstracts and extracted data from 71 studies reported in 58 relevant publications, to assess quantitatively whether phenotypic trait changes associated with climate change are adaptive in animals. A meta-analysis focussing on birds, the taxon best represented in our dataset, suggests that global warming has not systematically affected morphological traits, but has advanced phenological traits. We demonstrate that these advances are adaptive for some species, but imperfect as evidenced by the observed consistent selection for earlier timing. Application of a theoretical model indicates that the evolutionary load imposed by incomplete adaptive responses to ongoing climate change may already be threatening the persistence of species.
Topics: Acclimatization; Animals; Birds; Climate Change; Phenotype; Selection, Genetic; Time Factors
PubMed: 31337752
DOI: 10.1038/s41467-019-10924-4 -
Human Factors Dec 2019In this review, we detail the impact of environmental stress on cognitive and military task performance and highlight any individual characteristics or interventions...
OBJECTIVE
In this review, we detail the impact of environmental stress on cognitive and military task performance and highlight any individual characteristics or interventions which may mitigate any negative effect.
BACKGROUND
Military personnel are often deployed in regions markedly different from their own, experiencing hot days, cold nights, and trips both above and below sea level. In spite of these stressors, high-level cognitive and operational performance must be maintained.
METHOD
A systematic review of the electronic databases Medline (PubMed), EMBASE (Scopus), PsycINFO, and Web of Science was conducted from inception up to September 2018. Eligibility criteria included a healthy human cohort, an outcome of cognition or military task performance and assessment of an environmental condition.
RESULTS
The search returned 113,850 records, of which 124 were included in the systematic review. Thirty-one studies examined the impact of heat stress on cognition; 20 of cold stress; 59 of altitude exposure; and 18 of being below sea level.
CONCLUSION
The severity and duration of exposure to the environmental stressor affects the degree to which cognitive performance can be impaired, as does the complexity of the cognitive task and the skill or familiarity of the individual performing the task.
APPLICATION
Strategies to improve cognitive performance in extreme environmental conditions should focus on reducing the magnitude of the physiological and perceptual disturbance caused by the stressor. Strategies may include acclimatization and habituation, being well skilled on the task, and reducing sensations of thermal stress with approaches such as head and neck cooling.
Topics: Cognition; Environment; Humans; Military Personnel; Psychomotor Performance; Stress, Physiological
PubMed: 31002273
DOI: 10.1177/0018720819839817