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Creatine Supplementation and Lower Limb Strength Performance: A Systematic Review and Meta-Analyses.Sports Medicine (Auckland, N.Z.) Sep 2015Creatine is the most widely used supplementation to increase strength performance. However, the few meta-analyses are more than 10 years old and suffer from inclusion... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Creatine is the most widely used supplementation to increase strength performance. However, the few meta-analyses are more than 10 years old and suffer from inclusion bias such as the absence of randomization and placebo, the diversity of the inclusion criteria (aerobic/endurance, anaerobic/strength), no evaluation on specific muscles or group of muscles, and the considerable amount of conflicting results within the last decade.
OBJECTIVE
The objective of this systematic review was to evaluate meta-analyzed effects of creatine supplementation on lower limb strength performance.
METHODS
We conducted a systematic review and meta-analyses of all randomized controlled trials comparing creatine supplementation with a placebo, with strength performance of the lower limbs measured in exercises lasting less than 3 min. The search strategy used the keywords "creatine supplementation" and "performance". Dependent variables were creatine loading, total dose, duration, the time-intervals between baseline (T0) and the end of the supplementation (T1), as well as any training during supplementation. Independent variables were age, sex, and level of physical activity at baseline. We conducted meta-analyses at T1, and on changes between T0 and T1. Each meta-analysis was stratified within lower limb muscle groups and exercise tests.
RESULTS
We included 60 studies (646 individuals in the creatine supplementation group and 651 controls). At T1, the effect size (ES) among stratification for squat and leg press were, respectively, 0.336 (95 % CI 0.047-0.625, p = 0.023) and 0.297 (95 % CI 0.098-0.496, p = 0.003). Overall quadriceps ES was 0.266 (95 % CI 0.150-0.381, p < 0.001). Global lower limb ES was 0.235 (95 % CI 0.125-0.346, p < 0.001). Meta-analysis on changes between T0 and T1 gave similar results. The meta-regression showed no links with characteristics of population or of supplementation, demonstrating the creatine efficacy effects, independent of all listed conditions.
CONCLUSION
Creatine supplementation is effective in lower limb strength performance for exercise with a duration of less than 3 min, independent of population characteristic, training protocols, and supplementary doses and duration.
Topics: Adolescent; Adult; Aged; Creatine; Dietary Supplements; Female; Humans; Leg; Male; Middle Aged; Muscle Strength; Young Adult
PubMed: 25946994
DOI: 10.1007/s40279-015-0337-4 -
Sports Medicine - Open Dec 2017Brazilian jiu-jitsu is a grappling combat sport that has intermittency as its core element; in other words, actions of high, moderate and low intensity are interspersed... (Review)
Review
BACKGROUND
Brazilian jiu-jitsu is a grappling combat sport that has intermittency as its core element; in other words, actions of high, moderate and low intensity are interspersed during matches, requiring a high level of conditioning to support optimal levels of performance for the total match time. The athletes perform from four to six matches during a day of competition, and this number may increase if the open-class competition, which is held parallel to the competition by weight class, is considered. This systematic review examined the physical and physiological profiles of Brazilian jiu-jitsu athletes.
METHODS
Only scientific researches dealing with the major fitness components of Brazilian jiu-jitsu athletes (i.e. body composition and somatotype, aerobic and anaerobic profiles, muscular strength and power) and using accepted methods that provided relevant practical applications for a Brazilian jiu-jitsu athlete's fitness training and/or performance were included in the current review. A computer literature search was carried out of the PubMed, ISI Web of Knowledge, SportDiscus and Scopus databases (up to January 2016).
RESULTS
The database research generated 205 articles. After the application of inclusion and exclusion criteria, 58 studies were included for the present systematic review. A total of 1496 subjects were involved in all the selected investigations.
CONCLUSIONS
Body fat is generally low for these athletes and the mesomorphic component is predominant. The different studies showed VO values between 42 and 52 mL/kg/min, and it seems that aerobic fitness does not discriminate among Brazilian jiu-jitsu athletes of different competitive levels. There is a lack of scientific studies that have investigated anaerobic responses both in lower and upper limbs. Maximal dynamic, isometric and endurance strength can be associated with sporting success in Brazilian jiu-jitsu athletes. Although decisive actions during Brazilian jiu-jitsu matches are mainly dependent on muscular power, more specific studies are necessary to describe it. Studies involving the female sex should be conducted. In addition, further research is needed to analyse whether there are differences between sex, belt ranks and competitive level, and among the different weight categories for different variables.
PubMed: 28194734
DOI: 10.1186/s40798-016-0069-5 -
Nutrients Aug 2020Beta-alanine supplementation (BA) has a positive impact on physical performance. However, evidence showing a benefit of this amino acid in aerobic-anaerobic transition... (Meta-Analysis)
Meta-Analysis
Beta-alanine supplementation (BA) has a positive impact on physical performance. However, evidence showing a benefit of this amino acid in aerobic-anaerobic transition zones is scarce and the results controversial. The aim of this systematic review and meta-analysis is to analyze the effects of BA supplementation on physical performance in aerobic-anaerobic transition zones. At the same time, the effect of different dosages and durations of BA supplementation were identified. The search was designed in accordance with the PRISMA guidelines for systematic reviews and meta-analyses and performed in Web of Science (WOS), Scopus, SPORTDiscus, PubMed, and MEDLINE between 2010 and 2020. The methodological quality and risk of bias were evaluated with the Cochrane Collaboration tool. The main variables were the Time Trial Test (TTT) and Time to Exhaustion (TTE) tests, the latter separated into the Limited Time Test (LTT) and Limited Distance Test (LDT). The analysis was carried out with a pooled standardized mean difference (SMD) through Hedges' g test (95% CI). Nineteen studies were included in the systematic review and meta-analysis, revealing a small effect for time in the TTT (SMD, -0.36; 95% CI, -0.87-0.16; I = 59%; = 0.010), a small effect for LTT (SMD, 0.25; 95% CI, -0.01-0.51; I = 0%; = 0.53), and a large effect for LDT (SMD, 4.27; 95% CI, -0.25-8.79; I = 94%; = 0.00001). BA supplementation showed small effects on physical performance in aerobic-anaerobic transition zones. Evidence on acute supplementation is scarce (one study); therefore, exploration of acute supplementation with different dosages and formats on physical performance in aerobic-anaerobic transition zones is needed.
Topics: Aerobiosis; Anaerobiosis; Dietary Supplements; Humans; Physical Functional Performance; Sports Nutritional Physiological Phenomena; beta-Alanine
PubMed: 32824885
DOI: 10.3390/nu12092490 -
The Journal of Sports Medicine and... Jan 2019The aim of the present systematic review was to profile soccer players' anthropometric, physiological, and physical attributes relative to different competitive levels,...
INTRODUCTION
The aim of the present systematic review was to profile soccer players' anthropometric, physiological, and physical attributes relative to different competitive levels, playing positions and age groups.
EVIDENCE ACQUISITION
The systematic search was conducted using different databases and according to the Population/Intervention or Exposure/Comparison/Outcome(s) [PICO] criteria.
EVIDENCE SYNTHESIS
The present review shows that the somatotype characteristics, percentage (%) of body fat, maximal oxygen uptake (VO2max), repeated-sprint ability (RSA), running speed, strength, and muscular power of the lower limbs were the most powerful discriminators between male soccer players of different competitive levels, playing positions, and age groups. Specifically, higher VO2max, muscle strength, muscular power (vertical jump height), running speed (10-30 m) and agility, and lower % of body fat were identified in elite soccer players (higher-level) compared to all other competitive levels (i.e., lower-level: sub-elite, amateur, recreational). As for the competitive level differences, higher VO2max, mean anaerobic power, RSA and sprint performances (5 to 20 m), and lower % of body fat and lower limbs' explosive capabilities (countermovement jump [CMJ] and squat jump [SJ]) were found in outfielders (forwards, midfielders, and defenders) as compared to goalkeepers, from a very youth age (8 years old). Concerning age-related performance, it appears that physical performance increased significantly with age.
CONCLUSIONS
These data, together with the fact that each position, age category, and playing level has a different physiological background in male soccer players, demonstrate that training programs should be individualized to each position, playing level and age category, as is already done with goalkeepers.
Topics: Adolescent; Anthropometry; Athletes; Athletic Performance; Body Composition; Child; Humans; Lower Extremity; Male; Muscle Strength; Oxygen Consumption; Running; Soccer; Somatotypes
PubMed: 29199782
DOI: 10.23736/S0022-4707.17.07950-6 -
Sports Medicine (Auckland, N.Z.) Nov 2022Sleep loss may influence subsequent physical performance. Quantifying the impact of sleep loss on physical performance is critical for individuals involved in athletic... (Meta-Analysis)
Meta-Analysis
BACKGROUND
Sleep loss may influence subsequent physical performance. Quantifying the impact of sleep loss on physical performance is critical for individuals involved in athletic pursuits.
DESIGN
Systematic review and meta-analysis.
SEARCH AND INCLUSION
Studies were identified via the Web of Science, Scopus, and PsycINFO online databases. Investigations measuring exercise performance under 'control' (i.e., normal sleep, > 6 h in any 24 h period) and 'intervention' (i.e., sleep loss, ≤ 6 h sleep in any 24 h period) conditions were included. Performance tasks were classified into different exercise categories (anaerobic power, speed/power endurance, high-intensity interval exercise (HIIE), strength, endurance, strength-endurance, and skill). Multi-level random-effects meta-analyses and meta-regression analyses were conducted, including subgroup analyses to explore the influence of sleep-loss protocol (e.g., deprivation, restriction, early [delayed sleep onset] and late restriction [earlier than normal waking]), time of day the exercise task was performed (AM vs. PM) and body limb strength (upper vs. lower body).
RESULTS
Overall, 227 outcome measures (anaerobic power: n = 58; speed/power endurance: n = 32; HIIE: n = 27; strength: n = 66; endurance: n = 22; strength-endurance: n = 9; skill: n = 13) derived from 69 publications were included. Results indicated a negative impact of sleep loss on the percentage change (%) in exercise performance (n = 959 [89%] male; mean % = - 7.56%, 95% CI - 11.9 to - 3.13, p = 0.001, I = 98.1%). Effects were significant for all exercise categories. Subgroup analyses indicated that the pattern of sleep loss (i.e., deprivation, early and late restriction) preceding exercise is an important factor, with consistent negative effects only observed with deprivation and late-restriction protocols. A significant positive relationship was observed between time awake prior to the exercise task and % in performance for both deprivation and late-restriction protocols (~ 0.4% decrease for every hour awake prior to exercise). The negative effects of sleep loss on different exercise tasks performed in the PM were consistent, while tasks performed in the AM were largely unaffected.
CONCLUSIONS
Sleep loss appears to have a negative impact on exercise performance. If sleep loss is anticipated and unavoidable, individuals should avoid situations that lead to experiencing deprivation or late restriction, and prioritise morning exercise in an effort to maintain performance.
Topics: Humans; Male; Female; Physical Endurance; Exercise; Physical Functional Performance; Sleep
PubMed: 35708888
DOI: 10.1007/s40279-022-01706-y -
Journal of Human Kinetics Aug 2019Beta-hydroxy-beta-methylbutyrate (HMB) has been used extensively as a dietary supplement for athletes and physically active people. HMB is a leucine metabolite, which is...
Beta-hydroxy-beta-methylbutyrate (HMB) has been used extensively as a dietary supplement for athletes and physically active people. HMB is a leucine metabolite, which is one of three branched chain amino acids. HMB plays multiple roles in the human body of which most important ones include protein metabolism, insulin activity and skeletal muscle hypertrophy. The ergogenic effects of HMB supplementation are related to the enhancement of sarcolemma integrity, inhibition of protein degradation (ubiquitin pathway), decreased cell apoptosis, increased protein synthesis (mTOR pathway), stimulation of the growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis and enhancement of muscle stem cells proliferation and differentiation. HMB supplementation has been carried out with various groups of athletes. In endurance and martial arts athletes, HMB supplementation revealed positive effects on specific aerobic capacity variables. Positive results were also disclosed in resistance trained athletes, where changes in strength, body fat and muscle mass as well as anaerobic performance and power output were observed. The purpose of this review was to present the main mechanisms of HMB action, especially related to muscle protein synthesis and degradation, and ergogenic effects on different types of sports and physical activities.
PubMed: 31531146
DOI: 10.2478/hukin-2019-0070 -
International Journal of Surgery... Sep 2016Hepatic ischemia reperfusion injury (IRI) is not only a pathophysiological process involving the liver, but also a complex systemic process affecting multiple tissues... (Review)
Review
Hepatic ischemia reperfusion injury (IRI) is not only a pathophysiological process involving the liver, but also a complex systemic process affecting multiple tissues and organs. Hepatic IRI can seriously impair liver function, even producing irreversible damage, which causes a cascade of multiple organ dysfunction. Many factors, including anaerobic metabolism, mitochondrial damage, oxidative stress and secretion of ROS, intracellular Ca(2+) overload, cytokines and chemokines produced by KCs and neutrophils, and NO, are involved in the regulation of hepatic IRI processes. Matrix Metalloproteinases (MMPs) can be an important mediator of early leukocyte recruitment and target in acute and chronic liver injury associated to ischemia. MMPs and neutrophil gelatinase-associated lipocalin (NGAL) could be used as markers of I-R injury severity stages. This review explores the relationship between factors and inflammatory pathways that characterize hepatic IRI, MMPs and current pharmacological approaches to this disease.
Topics: Animals; Antioxidants; Biomarkers; Cytokines; Genetic Therapy; Hepatectomy; Kupffer Cells; Leukocytes; Liver; Liver Diseases; Liver Transplantation; Male; Matrix Metalloproteinases; Mitochondria, Liver; Oxidative Stress; Prognosis; Reperfusion Injury; Risk Assessment
PubMed: 27255130
DOI: 10.1016/j.ijsu.2016.05.050 -
Cureus Sep 2023Using the guidelines from the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), this meta-analysis (MA) tried to figure out how well creatine... (Review)
Review
Using the guidelines from the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), this meta-analysis (MA) tried to figure out how well creatine (Cr) improves metabolic performance. We searched Google Scholar, PubMed, and the Cochrane Library to identify relevant randomized clinical trials (RCTs) exploring the various effects of Cr across different age groups compared to a placebo (PLA). We also investigated the synergistic effects of combining other supplements with Cr. In order to emphasize the different ways and sports where Cr has been used in the past years, we found from the selected articles that Cr demonstrated a more pronounced effect during aerobic or anaerobic exercise compared to PLA groups in the studies. Furthermore, in sports that demand significant cumulative energy, such as long-distance races, biking, or triathlons, athletes have observed performance enhancements with Cr supplementation. We also stipulate that Cr enhances resistance training in people over 50 years old and that adding other training supplements, such as β-hydroxy β-methylbutyrate (HMB), synergistically improves training outcomes when combined with Cr. The current MA was based on a thorough analysis of 10 separate studies. When these results were added together, we found that taking Cr supplements demonstrated statistically significant benefits over PLA. In conclusion, the present MA has found evidence that Cr has positive effects on metabolic outcomes for people who consume it.
PubMed: 37720119
DOI: 10.7759/cureus.45282 -
Nutrients Jul 2022Although the effects of caffeine supplementation on combat sports performance have been extensively investigated, there is currently no consensus regarding its ergogenic... (Meta-Analysis)
Meta-Analysis Review
Acute Effects of Caffeine Supplementation on Physical Performance, Physiological Responses, Perceived Exertion, and Technical-Tactical Skills in Combat Sports: A Systematic Review and Meta-Analysis.
Although the effects of caffeine supplementation on combat sports performance have been extensively investigated, there is currently no consensus regarding its ergogenic benefits.This systematic review with meta-analysis aimed to summarize the studies investigating the effects of caffeine supplementation on different aspects of performance in combat sports and to quantitatively analyze the results of these studies to better understand the ergogenic effect of caffeine on combat sports outcomes. A systematic search for randomized placebo-controlled studies investigating the effects of caffeine supplementation on combat sports' performance was performed through Scopus, Pubmed, Web of Science and Cochrane Library databases up to 18 April 2022. Random-effects meta-analyses of standardized mean differences (Hedge's g) were performed to analyze the data. Twenty-six studies of good and excellent methodological quality (based on the Pedro scale) fulfilled the inclusion criteria. The meta-analysis results revealed caffeine has a small but evident effect size (ES) on handgrip strength (ES = 0.28; 95% CI: 0.04 to 0.52; = 0.02), and total number of throws during the special judo fitness test (SJFT) (ES = 0.42; 95% CI: 0.06 to 0.78; = 0.02). Regarding the physiological responses, caffeine increased blood lactate concentration ([La]) in anaerobic exercise (ES = 1.23; 95% CI: 0.29 to 2.18; = 0.01) and simulated combat (ES = 0.91; 95% CI: 0.34 to 1.47; = 0.002). For Heart Rate (HR), caffeine increased HR final (ES = 0.31; 95% CI: 0.11 to 0.52; = 0.003), and HR 1min (ES = 0.20; 95% CI 0.004 to 0.40; = 0.045). However, caffeine had no impact on the countermovement jump height, the SJFT index, the judogi strength-endurance test, the number and duration of offensive actions, HR at the end of the fight, and the rating of perceived exertion. Caffeine supplementation may be ergogenic for a range of combat sports aspects involving isometric strength, anaerobic power, reaction time, and anaerobic metabolism. However, supplementation effects might be ineffective under certain circumstances, indicating supplementation needs to take into account the performance metric in question prior to creating a dosing protocol.
Topics: Athletic Performance; Caffeine; Dietary Supplements; Hand Strength; Performance-Enhancing Substances; Physical Exertion; Physical Functional Performance
PubMed: 35889953
DOI: 10.3390/nu14142996 -
Frontiers in Cellular and Infection... 2021, first described in 1999, is a prevalent bacterial species of the vaginal microbiome. As does not easily grow on de Man-Rogosa-Sharpe agar, but can grow anaerobically... (Review)
Review
, first described in 1999, is a prevalent bacterial species of the vaginal microbiome. As does not easily grow on de Man-Rogosa-Sharpe agar, but can grow anaerobically on blood agar, it has been initially overlooked by traditional culture methods. It was not until the wide application of molecular biology techniques that the function of in the vaginal microbiome was carefully explored. has the smallest genome among known and it has many probiotic characteristics, but is partly different from other major vaginal species, such as , in contributing to the maintenance of a healthy vaginal microbiome. It is not only commonly present in the healthy vagina but quite often recovered in high numbers in bacterial vaginosis (BV). Increasing evidence suggests that is a transitional species that colonizes after the vaginal environment is disturbed and offers overall less protection against vaginal dysbiosis and, subsequently, leads to BV, sexually transmitted infections, and adverse pregnancy outcomes. Accordingly, under certain conditions, is a genuine vaginal symbiont, but it also seems to be an opportunistic pathogen. Further studies are necessary to identify the exact role of this intriguing species in vaginal health and diseases.
Topics: Dysbiosis; Female; Humans; Lactobacillus; Pregnancy; Vagina; Vaginosis, Bacterial
PubMed: 34881196
DOI: 10.3389/fcimb.2021.792787