59 research outputs found
The acute effects of plyometric and sled towing stimuli with and without caffeine ingestion on vertical jump performance in professional soccer players
Abstract Background Post-activation potentiation (PAP) is the phenomenon by which muscular performance is enhanced in response to a conditioning stimulus. PAP has typically been evidenced via improved counter movement jump (CMJ) performance. This study examined the effects of PAP, with and without prior caffeine ingestion, on CMJ performance. Methods Twelve male professional soccer players (23 ± 5 years) performed two trials of plyometric exercises and sled towing 60 min after placebo or caffeine ingestion (5 mg.kg− 1) in a randomized, counterbalanced and double-blinded design. CMJ performance was assessed at baseline and 1, 3 and 5 min after the conditioning stimulus (T1, T3 and T5, respectively). Results Two way ANOVA main effects indicated a significant difference in jump height after the PAP protocol (F[3, 11] = 14.99, P 0.05) compared to placebo. Conclusions The results of this study suggest that acute plyometric and sled towing stimuli enhances jump performance and that this potentiation is augmented by caffeine ingestion in male soccer players
Pre-Operative Cognitive Functioning and Inflammatory and Neuroendocrine Responses to Cardiac Surgery.
BACKGROUND: Cognitive functioning is linked to cardiac mortality and morbidity, but the mechanisms underlying this relationship are unclear. PURPOSE: To examine the relationship between pre-operative cognitive functioning and post-operative inflammatory and neuroendocrine responses in patients undergoing coronary artery bypass graft (CABG) surgery. METHODS: One-hundred ninety-three outpatients were screened to assess their cognitive function using the Montreal Cognitive Assessment (MoCA) on average 30 days prior to CABG surgery and provided blood samples for the measurement of interleukin (IL)-6 and C-reactive protein (CRP) and saliva samples for the measurement of diurnal cortisol. Participants were followed-up 4-8 days following surgery for the repeat measurement of IL-6 and CRP and 60 days after surgery for the measurement of diurnal salivary cortisol. RESULTS: Patients with low cognitive function (MoCA < 26) prior to surgery reached higher IL-6 concentrations in the days after surgery (β = -0.212, p = 0.021) and had greater cortisol output across the day 2 months after surgery (β = -0.179, p = 0.044). CONCLUSIONS: Low cognitive functioning is associated with a more negative pattern of biological response to surgery, indicative of poorer physical recovery. These pathways may contribute to the links between cognitive function and cardiovascular pathology
Inheritance of DNA methylation level in healthy human tissues
DNA methylation (DNAm) is the covalent modification of DNA by addition of a
methyl group primarily at the cytosine directly upstream of a guanine. DNAm level
plays a central role in transcriptional regulation and is linked to disease. Therefore,
understanding genetic and environmental influences on DNAm level in healthy
tissue is an important step in the elucidation of trait and disease etiology. However,
at present only a minority of easy to access human tissues and ethnicities have been
investigated.
Therefore, we studied DNAm level measured in five human tissues: cerebellum,
frontal cortex, pons, temporal cortex and colon in either North American or South
American samples. We applied a novel statistical approach to estimate the
heritability attributable to genomic regions (regional heritability, ĥ²/r,g ) for DNAm
level at thousands of individual DNAm sites genome-wide.
In all five tissues, DNAm level was significantly associated with the local genomic
region for more DNAm sites than expected by chance. Moreover, DNAm level could
be predicted from the local sequence variants with an accuracy that scaled with the
estimated ĥ²/r,g .
Our results inform on molecular mechanisms regulating DNAm level and trait
etiology in several ways. Firstly, DNAm level at DNAm sites located in genomic risk
regions and measured in a tissue relevant to the disease can be influenced by the
local genetic variants. Specifically, we found that genetic variation within a region
associated with Fluid Intelligence was also associated with local DNAm level at the
proline-rich coiled-coil 1 (PRRC1) gene in healthy temporal cortex tissue.
Additionally, we replicated the finding of a Colorectal Cancer risk variant
(rs4925386) associated with two DNAm sites in healthy colon tissue. More
generally, we showed that DNAm sites located within a susceptibility region and
measured in a relevant tissue exhibit a similar overall pattern of estimated ĥ²/r,g to
DNAm sites outwith a susceptibility region. Secondly, the propensity for DNAm
level to be associated with the local sequence variation differs with respect to CpG
dinucleotide density and genic location. Most notably, DNAm sites located in CpG
dense regions of the genome are less likely to be heritable than DNAm sites located
in CpG sparse regions of the genome. Additionally, within both CpG dense and CpG
sparse regions of the genome intergenic DNAm sites are more likely to be heritable
than intragenic DNAm sites. Overall, our study suggests that variation in DNAm
level at some DNAm sites is at least partially controlled by nuclear genetic variation.
Moreover, DNAm level in healthy tissue has the potential to act as an intermediary in
trait variation and etiology
Effect of carbohydrate mouth rinsing on multiple sprint performance
BACKGROUND: Research suggests that carbohydrate mouth rinsing (CMR) improves endurance performance; yet, little is known regarding the effect of CMR on multiple sprint efforts. As many sports involve multiple sprinting efforts, followed by periods of recovery, the aim of our current study was to investigate the influence of CMR on multiple sprint performance. METHODS: We recruited eight active males (Age; 22 ± 1 y; 75.0 ± 8.8 kg; estimated VO2(max) 52.0 ± 3.0 ml/kg/min) to participate in a randomly assigned, double-blind, counterbalanced study administering a CMR (6.4% Maltodextrin) or similarly flavoured placebo solution. Primary outcomes for our study included: (a) time for three repeated sprint ability tests (RSA) and (b) the Loughborough Intermittent Shuttle Test (LIST). Time was expressed in seconds (sec). Secondary outcomes included ratings of perceived exertion (RPE) and blood glucose concentration. Tertiary outcomes included two psychological assessments designed to determine perceived activation (i.e., arousal) and pleasure-displeasure after each section of the LIST. We analysed our data using a two-way analysis of variance (ANOVA) for repeated measures, a Bonferroni adjusted post hoc t-test to determine significant differences in treatment, and a liberal 90% confidence interval between treatment conditions. Effect sizes were calculated between trials and interpreted as ≤ 0.2 trivial, > 0.2 small, > 0.6 moderate, > 1.2 large, > 2 very large and > 4 extremely large. Data are means ± SD. Overall statistical significance was set as P < 0.05; yet, modified accordingly when Bonferroni adjustments were made. RESULTS: Overall, we observed no significant difference in average (3.46 ± 0.2 vs. 3.44 ± 0.17; P = 0.11) or fastest time (3.38 ± 0.2 vs. 3.37 ± 0.2; P = 0.39) in the RSA test for the placebo vs. CMR conditions, respectively. Similar findings were also noted for the placebo vs. CMR, respectively, during the LIST test (3.52 ± 0.2 vs. 3.54 ± 0.2 sec; P = 0.63). Despite a significantly higher within group RPE during the 3rd and 4th sections of the LIST (< 0.05), no between group differences were otherwise noted. No differences were noted for blood glucose concentrations throughout the testing protocol. Lastly, from a psychological perspective, we observed no differences in pleasure-displeasure or perceived activation. CONCLUSIONS: The results of our current study suggest that CMR does not improve exercise performance, RPE or perceived pleasure-displeasure during high intensity activity requiring repeated, intermittent, sprint efforts
Unspoken inequality: How COVID-19 has exacerbated existing vulnerabilities of asylum-seekers, refugees, and undocumented migrants in South Africa
An estimated 2 million foreign-born migrants of working age (15-64) were living in South Africa (SA) in 2017. Structural and practical xenophobia has driven asylum-seekers, refugees, and undocumented migrants in SA to abject poverty and misery. The Coronavirus Disease 2019 (COVID-19) containment measures adopted by the SA government through the lockdown of the nation have tremendously deepened the unequal treatment of asylum-seekers and refugees in SA. This can be seen through the South African government's lack of consideration of this marginalized population in economic, poverty, and hunger alleviation schemes. Leaving this category of our society out of the national response safety nets may lead to negative coping strategies causing mental health issues and secondary health concerns. An effective response to the socioeconomic challenges imposed by the COVID-19 pandemic should consider the economic and health impact of the pandemic on asylum-seekers, refugees, and undocumented migrants
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