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Sports Medicine (Auckland, N.Z.) Jan 2015Protein supplements are frequently consumed by athletes and recreationally active adults to achieve greater gains in muscle mass and strength and improve physical... (Review)
Review
BACKGROUND
Protein supplements are frequently consumed by athletes and recreationally active adults to achieve greater gains in muscle mass and strength and improve physical performance.
OBJECTIVE
This review provides a systematic and comprehensive analysis of the literature that tested the hypothesis that protein supplements accelerate gains in muscle mass and strength resulting in improvements in aerobic and anaerobic power. Evidence statements were created based on an accepted strength of recommendation taxonomy.
DATA SOURCES
English language articles were searched through PubMed and Google Scholar using protein and supplements together with performance, exercise, strength, and muscle, alone or in combination as keywords. Additional articles were retrieved from reference lists found in these papers.
STUDY SELECTION
Studies recruiting healthy adults between 18 and 50 years of age that evaluated the effects of protein supplements alone or in combination with carbohydrate on a performance metric (e.g., one repetition maximum or isometric or isokinetic muscle strength), metrics of body composition, or measures of aerobic or anaerobic power were included in this review. The literature search identified 32 articles which incorporated test metrics that dealt exclusively with changes in muscle mass and strength, 5 articles that implemented combined resistance and aerobic training or followed participants during their normal sport training programs, and 1 article that evaluated changes in muscle oxidative enzymes and maximal aerobic power.
STUDY APPRAISAL AND SYNTHESIS METHODS
All papers were read in detail, and examined for experimental design confounders such as dietary monitoring, history of physical training (i.e., trained and untrained), and the number of participants studied. Studies were also evaluated based on the intensity, frequency, and duration of training, the type and timing of protein supplementation, and the sensitivity of the test metrics.
RESULTS
For untrained individuals, consuming supplemental protein likely has no impact on lean mass and muscle strength during the initial weeks of resistance training. However, as the duration, frequency, and volume of resistance training increase, protein supplementation may promote muscle hypertrophy and enhance gains in muscle strength in both untrained and trained individuals. Evidence also suggests that protein supplementation may accelerate gains in both aerobic and anaerobic power.
LIMITATIONS
To demonstrate measureable gains in strength and performance with exercise training and protein supplementation, many of the studies reviewed recruited untrained participants. Since skeletal muscle responses to exercise and protein supplementation differ between trained and untrained individuals, findings are not easily generalized for all consumers who may be considering the use of protein supplements.
CONCLUSIONS
This review suggests that protein supplementation may enhance muscle mass and performance when the training stimulus is adequate (e.g., frequency, volume, duration), and dietary intake is consistent with recommendations for physically active individuals.
Topics: Adult; Athletic Performance; Dietary Carbohydrates; Dietary Proteins; Dietary Supplements; Humans; Muscle Strength; Muscle, Skeletal; Physical Education and Training; Resistance Training
PubMed: 25169440
DOI: 10.1007/s40279-014-0242-2 -
Sports Medicine (Auckland, N.Z.) May 2018Middle- and long-distance running performance is constrained by several important aerobic and anaerobic parameters. The efficacy of strength training (ST) for distance... (Review)
Review
BACKGROUND
Middle- and long-distance running performance is constrained by several important aerobic and anaerobic parameters. The efficacy of strength training (ST) for distance runners has received considerable attention in the literature. However, to date, the results of these studies have not been fully synthesized in a review on the topic.
OBJECTIVES
This systematic review aimed to provide a comprehensive critical commentary on the current literature that has examined the effects of ST modalities on the physiological determinants and performance of middle- and long-distance runners, and offer recommendations for best practice.
METHODS
Electronic databases were searched using a variety of key words relating to ST exercise and distance running. This search was supplemented with citation tracking. To be eligible for inclusion, a study was required to meet the following criteria: participants were middle- or long-distance runners with ≥ 6 months experience, a ST intervention (heavy resistance training, explosive resistance training, or plyometric training) lasting ≥ 4 weeks was applied, a running only control group was used, data on one or more physiological variables was reported. Two independent assessors deemed that 24 studies fully met the criteria for inclusion. Methodological rigor was assessed for each study using the PEDro scale.
RESULTS
PEDro scores revealed internal validity of 4, 5, or 6 for the studies reviewed. Running economy (RE) was measured in 20 of the studies and generally showed improvements (2-8%) compared to a control group, although this was not always the case. Time trial (TT) performance (1.5-10 km) and anaerobic speed qualities also tended to improve following ST. Other parameters [maximal oxygen uptake ([Formula: see text]), velocity at [Formula: see text], blood lactate, body composition] were typically unaffected by ST.
CONCLUSION
Whilst there was good evidence that ST improves RE, TT, and sprint performance, this was not a consistent finding across all works that were reviewed. Several important methodological differences and limitations are highlighted, which may explain the discrepancies in findings and should be considered in future investigations in this area. Importantly for the distance runner, measures relating to body composition are not negatively impacted by a ST intervention. The addition of two to three ST sessions per week, which include a variety of ST modalities are likely to provide benefits to the performance of middle- and long-distance runners.
Topics: Adolescent; Adult; Female; Humans; Male; Muscle Strength; Oxygen Consumption; Physical Endurance; Plyometric Exercise; Resistance Training; Running; Young Adult
PubMed: 29249083
DOI: 10.1007/s40279-017-0835-7 -
International Journal of Sports... Jun 2022This review aimed to determine (1) performance and training characteristics such as training intensity distribution (TID), volume, periodization, and methods in highly...
PURPOSE
This review aimed to determine (1) performance and training characteristics such as training intensity distribution (TID), volume, periodization, and methods in highly trained/elite distance runners and (2) differences in training volume and TID between event distances in highly trained/elite distance runners.
METHODS
A systematic review of the literature was carried out using the PubMed/MEDLINE, Scopus, and Web of Science databases.
RESULTS
Ten articles met the inclusion criteria. Highly trained/elite distance runners typically follow a pyramidal TID approach, characterized by a decreasing training volume from zone 1 (at or below speed at first ventilatory/lactate threshold [LT]) to zone 2 (between speeds associated with either both ventilatory thresholds or 2 and 4 mmol·L-1 LTs [vLT1 and vLT2, respectively]) and zone 3 (speed above vVT2/vLT2). Continuous-tempo runs or interval training sessions at vLT2 in zone 2 (ie, medium and long aerobic intervals) and those in zone 3 (ie, anaerobic or short-interval training) were both used at least once per week each in elite runners, and they were used to increase the number of either vLT2 or z3 sessions to adopt either a pyramidal or a polarized approach, respectively. More pyramidal- and polarized-oriented approaches were used by marathoners and 1500-m runners, respectively.
CONCLUSIONS
Highly trained and elite middle- and long-distance runners are encouraged to adopt a traditional periodization pattern with a hard day-easy day basis, consisting in a shift from a pyramidal TID used during the preparatory and precompetitive periods toward a polarized TID during the competitive period.
Topics: Humans; Lactic Acid; Oxygen Consumption; Physical Endurance; Running
PubMed: 35418513
DOI: 10.1123/ijspp.2021-0435 -
Cardiovascular Therapeutics 2022The purpose of this study is to compare the effects of high-intensity interval training (HIIT) versus moderate-intensity continuous training (MICT) on exercise capacity... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
The purpose of this study is to compare the effects of high-intensity interval training (HIIT) versus moderate-intensity continuous training (MICT) on exercise capacity and several prognostic markers in patients with coronary artery disease (CAD) and heart failure (HF).
METHODS
This systematic review is registered on the INPLASY website (number: INPLASY202080112). We conducted a comprehensive search in eight databases of literature before September 13, 2019. Trials comparing HIIT and MICT in participants with CAD or HF aged 52-78 years were included. Exercise capacity (peak oxygen consumption (peak VO)) and prognostic markers, such as the anaerobic threshold (AT), minute ventilation/carbon dioxide production (VE/VCO) slope, left ventricular ejection fraction (LVEF), and prognostic value of the predicted VO max per cent (the predicted VO peak (%)) were examined.
RESULTS
A total of 15 studies were included comprising 664 patients, 50% of which were male, with an average age of 60.3 ± 13.2 years. For patients with CAD, HIIT significantly improved peak VO values (95% CI 0.7 to 2.11) compared with MICT, but peak VO values in patients with HF did not seem to change. For training lasting less than eight weeks, HIIT significantly improved peak VO values (95% CI 0.70 to 2.10), while HIIT lasting 12 weeks or longer resulted in a modestly increased peak VO value (95% CI 0.31 to 5.31). High-intensity interval training significantly increased the AT when compared with MICT (95% CI 0.50 to 1.48). High-intensity interval training also caused a moderate increase in LVEF (95% CI 0.55 to 5.71) but did not have a significant effect on the VE/VCO slope (95% CI -2.32 to 0.98) or the predicted VO peak (95% CI -2.54 to 9.59) compared with MICT.
CONCLUSIONS
High-intensity interval training is an effective therapy for improving peak VO values in patients with CAD. High-intensity interval training in the early stage (eight weeks or fewer) is superior to MICT. Finally, HIIT significantly improved prognostic markers, including the AT and LVEF in patients with CAD and HF.
Topics: Aged; Coronary Artery Disease; Exercise Tolerance; Female; Heart Failure; High-Intensity Interval Training; Humans; Male; Middle Aged; Oxygen Consumption; Prognosis; Stroke Volume; Ventricular Function, Left
PubMed: 35801132
DOI: 10.1155/2022/4273809 -
Nutrients Mar 2019Studies have shown that creatine supplementation increases intramuscular creatine concentrations, favoring the energy system of phosphagens, which may help explain the... (Meta-Analysis)
Meta-Analysis
Studies have shown that creatine supplementation increases intramuscular creatine concentrations, favoring the energy system of phosphagens, which may help explain the observed improvements in high-intensity exercise performance. However, research on physical performance in soccer has shown controversial results, in part because the energy system used is not taken into account. The main aim of this investigation was to perform a systematic review and meta-analysis to determine the efficacy of creatine supplementation for increasing performance in skills related to soccer depending upon the type of metabolism used (aerobic, phosphagen, and anaerobic metabolism). A structured search was carried out following the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines in the Medline/PubMed and Web of Science, Cochrane Library, and Scopus databases until January 2019. The search included studies with a double-blind and randomized experimental design in which creatine supplementation was compared to an identical placebo situation (dose, duration, timing, and drug appearance). There were no filters applied to the soccer players' level, gender, or age. A final meta-analysis was performed using the random effects model and pooled standardized mean differences (SMD) (Hedges's ). Nine studies published were included in the meta-analysis. This revealed that creatine supplementation did not present beneficial effects on aerobic performance tests (SMD, -0.05; 95% confidence interval (CI), -0.37 to 0.28; = 0.78) and phosphagen metabolism performance tests (strength, single jump, single sprint, and agility tests: SMD, 0.21; 95% CI, -0.03 to 0.45; = 0.08). However, creatine supplementation showed beneficial effects on anaerobic performance tests (SMD, 1.23; 95% CI, 0.55⁻1.91; <0.001). Concretely, creatine demonstrated a large and significant effect on Wingate test performance (SMD, 2.26; 95% CI, 1.40⁻3.11; <0.001). In conclusion, creatine supplementation with a loading dose of 20⁻30 g/day, divided 3⁻4 times per day, ingested for 6 to 7 days, and followed by 5 g/day for 9 weeks or with a low dose of 3 mg/kg/day for 14 days presents positive effects on improving physical performance tests related to anaerobic metabolism, especially anaerobic power, in soccer players.
Topics: Athletic Performance; Creatine; Dietary Supplements; Humans; Male; Soccer
PubMed: 30935142
DOI: 10.3390/nu11040757 -
Scandinavian Journal of Medicine &... May 2022The effects of short sprint interval training (sSIT) with efforts of ≤10 s on maximal oxygen consumption (V̇O max), aerobic and anaerobic performances remain... (Meta-Analysis)
Meta-Analysis Review
The effects of short sprint interval training (sSIT) with efforts of ≤10 s on maximal oxygen consumption (V̇O max), aerobic and anaerobic performances remain unknown. To verify the effectiveness of sSIT in physically active adults and athletes, a systematic literature search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The databases PubMed/MEDLINE, ISI Web of Science, and SPORTDiscus were systematically searched on May 9, 2020, and updated on September 14, 2021. Inclusion criteria were based on PICO and included healthy athletes and active adults of any sex (≤40 years), performing supervised sSIT (≤10 s of "all-out" and non-"all-out" efforts) of at least 2 weeks, with a minimum of 6 sessions. As a comparator, a non-sSIT control group, another high-intensity interval training (HIIT) group, or a continuous training (CT) group were required. A total of 18 studies were deemed eligible. The estimated SMDs based on the random-effects model were -0.56 (95% CI: -0.79, -0.33, p < 0.001) for V̇O max, -0.43 (95% CI: -0.67, -0.20, p < 0.001) for aerobic performance, and -0.44 (95% CI: -0.70, -0.18, p < 0.001) for anaerobic performance after sSIT vs. no exercise/usual training. However, there were no significant differences (p > 0.05) for all outcomes when comparing sSIT vs. HIIT/CT. Our findings indicate a very high effectiveness of sSIT protocols in different exercise modes (e.g., cycling, running, paddling, and punching) to improve V̇O max, aerobic, and anaerobic performances in physically active young healthy adults and athletes.
Topics: Adult; Anaerobiosis; Exercise Test; High-Intensity Interval Training; Humans; Oxygen Consumption; Running
PubMed: 35090181
DOI: 10.1111/sms.14133 -
Scandinavian Journal of Medicine &... May 2018The effects of nutrition on exercise metabolism and performance remain an important topic among sports scientists, clinical, and athletic populations. Recently, fasted... (Meta-Analysis)
Meta-Analysis Review
The effects of nutrition on exercise metabolism and performance remain an important topic among sports scientists, clinical, and athletic populations. Recently, fasted exercise has garnered interest as a beneficial stimulus which induces superior metabolic adaptations to fed exercise in key peripheral tissues. Conversely, pre-exercise feeding augments exercise performance compared with fasting conditions. Given these seemingly divergent effects on performance and metabolism, an appraisal of the literature is warranted. This review determined the effects of fasting vs pre-exercise feeding on continuous aerobic and anaerobic or intermittent exercise performance, and post-exercise metabolic adaptations. A search was performed using the MEDLINE and PubMed search engines. The literature search identified 46 studies meeting the relevant inclusion criteria. The Delphi list was used to assess study quality. A meta-analysis and meta-regression were performed where appropriate. Findings indicated that pre-exercise feeding enhanced prolonged (P = .012), but not shorter duration aerobic exercise performance (P = .687). Fasted exercise increased post-exercise circulating FFAs (P = .023) compared to fed exercise. It is evidenced that pre-exercise feeding blunted signaling in skeletal muscle and adipose tissue implicated in regulating components of metabolism, including mitochondrial adaptation and substrate utilization. This review's findings support the hypothesis that the fasted and fed conditions can divergently influence exercise metabolism and performance. Pre-exercise feeding bolsters prolonged aerobic performance, while seminal evidence highlights potential beneficial metabolic adaptations that fasted exercise may induce in peripheral tissues. However, further research is required to fully elucidate the acute and chronic physiological adaptations to fasted vs fed exercise.
Topics: Adaptation, Physiological; Adipose Tissue; Athletic Performance; Energy Metabolism; Exercise; Fasting; Fatty Acids, Nonesterified; Humans; Muscle, Skeletal
PubMed: 29315892
DOI: 10.1111/sms.13054 -
Nutrients Jun 2022Nutritional ergogenic aids (NEAs) are substances included within the group of sports supplements. Although they are widely consumed by athletes, evidence-based analysis... (Meta-Analysis)
Meta-Analysis Review
Nutritional ergogenic aids (NEAs) are substances included within the group of sports supplements. Although they are widely consumed by athletes, evidence-based analysis is required to support training outcomes or competitive performance in specific disciplines. Combat sports have a predominant use of anaerobic metabolism as a source of energy, reaching peak exertion or sustained effort for very short periods of time. In this context, the use of certain NEAs could help athletes to improve their performance in those specific combat skills (i.e., the number of attacks, throws and hits; jump height; and grip strength, among others) as well as in general physical aspects (time to exhaustion [TTE], power, fatigue perception, heart rate, use of anaerobic metabolism, etc.). Medline/PubMed, Scopus and EBSCO were searched from their inception to May 2022 for randomised controlled trials (RCTs). Out of 677 articles found, 55 met the predefined inclusion criteria. Among all the studied NEAs, caffeine (5-10 mg/kg) showed strong evidence for its use in combat sports to enhance the use of glycolytic pathways for energy production during high-intensity actions due to a greater production of and tolerance to blood lactate levels. In this regard, abilities including the number of attacks, reaction time, handgrip strength, power and TTE, among others, were improved. Buffering supplements such as sodium bicarbonate, sodium citrate and beta-alanine may have a promising role in high and intermittent exertion during combat, but more studies are needed in grappling combat sports to confirm their efficacy during sustained isometric exertion. Other NEAs, including creatine, beetroot juice or glycerol, need further investigation to strengthen the evidence for performance enhancement in combat sports. Caffeine is the only NEA that has shown strong evidence for performance enhancement in combat sports.
Topics: Athletes; Athletic Performance; Caffeine; Dietary Supplements; Humans; Performance-Enhancing Substances; Sports Nutritional Physiological Phenomena
PubMed: 35807770
DOI: 10.3390/nu14132588 -
Journal of Clinical Medicine Mar 2023Aspiration pneumonia is increasingly recognised as a common condition. While antibiotics covering anaerobes are thought to be necessary based on old studies reporting... (Review)
Review
INTRODUCTION
Aspiration pneumonia is increasingly recognised as a common condition. While antibiotics covering anaerobes are thought to be necessary based on old studies reporting anaerobes as causative organisms, recent studies suggest that it may not necessarily benefit prognosis, or even be harmful. Clinical practice should be based on current data reflecting the shift in causative bacteria. The aim of this review was to investigate whether anaerobic coverage is recommended in the treatment of aspiration pneumonia.
METHODS
A systematic review and meta-analysis of studies comparing antibiotics with and without anaerobic coverage in the treatment of aspiration pneumonia was performed. The main outcome studied was mortality. Additional outcomes were resolution of pneumonia, development of resistant bacteria, length of stay, recurrence, and adverse effects. The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines were followed.
RESULTS
From an initial 2523 publications, one randomised control trial and two observational studies were selected. The studies did not show a clear benefit of anaerobic coverage. Upon meta-analysis, there was no benefit of anaerobic coverage in improving mortality (Odds ratio 1.23, 95% CI 0.67-2.25). Studies reporting resolution of pneumonia, length of hospital stay, recurrence of pneumonia, and adverse effects showed no benefit of anaerobic coverage. The development of resistant bacteria was not discussed in these studies.
CONCLUSION
In the current review, there are insufficient data to assess the necessity of anaerobic coverage in the antibiotic treatment of aspiration pneumonia. Further studies are needed to determine which cases require anaerobic coverage, if any.
PubMed: 36902779
DOI: 10.3390/jcm12051992 -
International Journal of Sport... Mar 2021CrossFit® is a high-intensity functional training method consisting of daily workouts called "workouts of the day." No nutritional recommendations exist for CrossFit®...
CrossFit® is a high-intensity functional training method consisting of daily workouts called "workouts of the day." No nutritional recommendations exist for CrossFit® that are supported by scientific evidence regarding the energetic demands of this type of activity or dietary and supplement interventions. This systematic review performed in accordance with PRISMA guidelines aimed to identify studies that determined (a) the physiological and metabolic demands of CrossFit® and (b) the effects of nutritional strategies on CrossFit® performance to guide nutritional recommendations for optimal recovery, adaptations, and performance for CrossFit® athletes and direct future research in this emerging area. Three databases were searched for studies that investigated physiological responses to CrossFit® and dietary or supplementation interventions on CrossFit® performance. Various physiological measures revealed the intense nature of all CrossFit® workouts of the day, reflected in substantial muscle fatigue and damage. Dietary and supplementation studies provided an unclear insight into effective strategies to improve performance and enhance adaptations and recovery due to methodological shortcomings across studies. This systematic review showed that CrossFit® is a high-intensity sport with fairly homogenous anaerobic and aerobic characteristics, resulting in substantial metabolic stress, leading to metabolite accumulation (e.g., lactate and hydrogen ions) and increased markers of muscle damage and muscle fatigue. Limited interventional data exist on dietary and supplementation strategies to optimize CrossFit® performance, and most are moderate to very low quality with some critical methodological limitations, precluding solid conclusions on their efficacy. High-quality work is needed to confirm the ideal dietary and supplemental strategies for optimal performance and recovery for CrossFit® athletes and is an exciting avenue for further research.
Topics: Athletic Performance; Biomedical Research; Diet; Dietary Supplements; Energy Metabolism; Forecasting; Heart Rate; Humans; Lactic Acid; Muscle Fatigue; Myalgia; Oxygen Consumption; Physical Conditioning, Human
PubMed: 33513565
DOI: 10.1123/ijsnem.2020-0223