Effects of acute caffeine intake on combat sports performance: A systematic review and meta-analysis.

The interest in the benefits of caffeine in combat sports has grown exponentially in the last few years, evidenced by the significant rise of post-competition urine caffeine concentration. We conduct a systematic review and meta-analysis on the effects of caffeine on different performance variables in combat sports athletes. In total, we included 25 studies. All studies included had blinded, and cross-over experimental designs, and we conducted a risk of bias analysis. For nonspecific outcomes, there was an ergogenic effect of caffeine on vertical jump height (SMD: 0.38; 95% CI: 0.04, 0.71) and reaction time (SMD: -0.98, 95% CI: -1.46,-0.50). For outcomes specific to combat sports, there was an increase in the number of throws with caffeine in the Special Judo Fitness Test (SMD: 0.62; 95% CI: 0.14, 1.09). Caffeine ingestion increased the number of offensive actions during combats (SMD: 0.40; 95% CI: 0.06, 0.74). Caffeine ingestion increased the duration of offensive actions during combat (SMD: 0.58; 95% CI: 0.21, 0.96). Finally, caffeine ingestion increased blood lactate concentration after bout 1 (SMD: 1.35) bout 2 (SMD: 1.43) and bout 3 (SMD: 1.98). Overall, athletes competing in combat sports may consider supplementing with caffeine for an acute increase in exercise performance.

The association between reallocations of time and health using compositional data analysis: a systematic scoping review with an interactive data exploration interface.

BACKGROUND: How time is allocated influences health. However, any increase in time allocated to one behaviour must be offset by a decrease in others. Recently, studies have used compositional data analysis (CoDA) to estimate the associations with health when reallocating time between different behaviours. The aim of this scoping review was to provide an overview of studies that have used CoDA to model how reallocating time between different time-use components is associated with health. METHODS: A systematic search of four electronic databases (MEDLINE, Embase, Scopus, SPORTDiscus) was conducted in October 2022. Studies were eligible if they used CoDA to examine the associations of time reallocations and health. Reallocations were considered between movement behaviours (sedentary behaviour (SB), light physical activity (LPA), moderate-to-vigorous physical activity (MVPA)) or various activities of daily living (screen time, work, household chores etc.). The review considered all populations, including clinical populations, as well as all health-related outcomes. RESULTS: One hundred and three studies were included. Adiposity was the most commonly studied health outcome (n = 41). Most studies (n = 75) reported reallocations amongst daily sleep, SB, LPA and MVPA. While other studies reported reallocations amongst sub-compositions of these (work MVPA vs. leisure MVPA), activity types determined by recall (screen time, household chores, passive transport etc.) or bouted behaviours (short vs. long bouts of SB). In general, when considering cross-sectional results, reallocating time to MVPA from any behaviour(s) was favourably associated with health and reallocating time away from MVPA to any behaviour(s) was unfavourably associated with health. Some beneficial associations were seen when reallocating time from SB to both LPA and sleep; however, the strength of the association was much lower than for any reallocations involving MVPA. However, there were many null findings. Notably, most of the longitudinal studies found no associations between reallocations of time and health. Some evidence also suggested the context of behaviours was important, with reallocations of leisure time toward MVPA having a stronger favourable association for health than reallocating work time towards MVPA. CONCLUSIONS: Evidence suggests that reallocating time towards MVPA from any behaviour(s) has the strongest favourable association with health, and reallocating time away from MVPA toward any behaviour(s) has the strongest unfavourable association with health. Future studies should use longitudinal and experimental study designs, and for a wider range of outcomes.

Effect of isolated and combined ingestion of caffeine and citrulline malate on resistance exercise and jumping performance: a randomized double-blind placebo-controlled crossover study.

PURPOSE: The aim of this study was to explore the isolated and combined effects of caffeine and citrulline malate (CitMal) on jumping performance, muscular strength, muscular endurance, and pain perception in resistance-trained participants. METHODS: Using a randomized and double-blind study design, 35 resistance-trained males (n = 18) and females (n = 17) completed four testing sessions following the ingestion of isolated caffeine (5 mg/kg), isolated CitMal (12 g), combined doses of caffeine and CitMal, and placebo. Supplements were ingested 60 min before performing a countermovement jump (CMJ) test (outcomes included jump height, rate of force development, peak force, and peak power), one-repetition maximum (1RM) squat and bench press, and repetitions to muscular failure in the squat and bench press with 60% of 1RM. Pain perception was evaluated following the repetitions to failure tests. The study was registered at ISRCTN (registration number: ISRCTN11694009). RESULTS: Compared to the placebo condition, isolated caffeine ingestion and co-ingestion of caffeine and CitMal significantly enhanced strength in 1RM bench press (Cohen's d: 0.05-0.06; 2.5-2.7%), muscular endurance in the squat (d: 0.46-0.58; 18.6-18.7%) and bench press (d: 0.48-0.64; 9.3-9.5%). However, there was no significant difference between isolated caffeine ingestion and caffeine co-ingested with CitMal, and isolated CitMal supplementation did not have an ergogenic effect in any outcome. No main effect of condition was found in the analysis for CMJ-derived variables, 1RM squat and pain perception. CONCLUSION: Caffeine ingestion appears to be ergogenic for muscular strength and muscular endurance, while adding CitMal does not seem to further enhance these effects.

Ergogenic Effects of Sodium Bicarbonate on Resistance Exercise: A Randomized, Double-Blind, Placebo-Controlled Study.

ABSTRACT: Varovic, D, Grgic, J, Schoenfeld, BJ, and Vuk, S. Ergogenic effects of sodium bicarbonate on resistance exercise: a randomized, double-blind, placebo-controlled study. J Strength Cond Res 37(8): 1600-1608, 2023-This study explored the effects of sodium bicarbonate ingestion on muscular endurance, power, and velocity in resistance exercise. Nineteen resistance-trained men ingested either 0.3 g·kg -1 of sodium bicarbonate or 0.21 g·kg -1 of placebo (sodium chloride) 180-60 minutes before exercise. The exercise protocol involved performing 3 sets with 70% of 1 repetition maximum to muscular failure in the bench press and biceps curl exercises. Analyzed outcomes included the number of repetitions performed in every set and throughout all 3 sets. In addition, power and velocity of the repetitions were explored by matching the number of repetitions between the sodium bicarbonate and placebo trials. In the bench press exercise, sodium bicarbonate increased the following: (a) the number of repetitions performed in the third set ( g : 0.30; p = 0.046), (b) the total number of repetitions performed throughout all 3 sets ( g : 0.23; p = 0.04), (c) peak power in the second set ( g : 0.19; p = 0.03), and (d) mean power ( g : 0.23; p = 0.03) and mean velocity ( g : 0.30; p = 0.02) in the third set. We did not find a significant difference between the conditions for any of the analyzed outcomes in the biceps curl exercise. Results indicate that sodium bicarbonate ingestion elicits an ergogenic effect on muscular endurance, power, and velocity in the bench press exercise. Given that ergogenic effects were observed only in the second and third sets, these data suggest that sodium bicarbonate acts by attenuating the suppressive effects of acidosis on muscle contractility.

Repetition Performance, Rating of Perceived Discomfort, and Blood Lactate Responses to Different Rest Interval Lengths in Single-Joint and Multijoint Lower-Body Exercise.

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.

Effects of caffeine on rate of force development: A meta-analysis.

This review aimed to conduct a meta-analysis of studies examining the effects of caffeine on rate of force development (RFD). Ten databases were searched to find relevant studies. Risk of bias (RoB) of the included studies was evaluated. Data were analyzed in a random-effects meta-analysis. Eleven studies with "some concerns" regarding RoB were included. In the main meta-analysis, there was a significant ergogenic effect of caffeine ingestion on RFD (Hedges' g = 0.37; 95% confidence interval [CI]: 0.21, 0.52; p < 0.0001). An ergogenic effect of caffeine was also found on RFD during resistance exercises (Hedges' g = 0.49; 95% CI: 0.30, 0.67; p < 0.0001), but not during the countermovement jump test (Hedges' g = 0.18; 95% CI: -0.02, 0.39; p = 0.08), with a significant difference between the subgroups (p = 0.03). Small-to-moderate (3-5 mg/kg; Hedges' g = 0.25; 95% CI: 0.09, 0.41; p = 0.002) and moderate-to-high caffeine doses (6-10 mg/kg) enhanced RFD (Hedges' g = 0.57; 95% CI: 0.30, 0.85; p < 0.0001), even though the effects were larger with higher caffeine doses (p = 0.04). Overall, caffeine ingestion increases RFD, which is relevant given that RFD is commonly associated with sport-specific tasks. From a practical perspective: (1) individuals interested in the acute enhancement of RFD in resistance exercise may consider supplementing with caffeine; and (2) given that evaluation of RFD is most commonly used for testing purposes, caffeine ingestion (3-10 mg/kg 60 min before exercise) should be standardized before RFD assessments.

Effects of high-intensity interval training (HIIT) and sprint interval training (SIT) on fat oxidation during exercise: a systematic review and meta-analysis.

OBJECTIVE: To investigate the effects of high-intensity interval training (HIIT) and sprint interval training (SIT) on fat oxidation during exercise (FatOx) and how they compare with the effects of moderate-intensity continuous training (MICT). DESIGN: Systematic review and meta-analysis. DATA SOURCES: Academic Search Ultimate, CINAHL, Networked Digital Library of Theses and Dissertations, Open Access Theses and Dissertations, OpenDissertations, PubMed/MEDLINE, Scopus, SPORTDiscus and Web of Science. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Studies using a between-group design, involving adult participants who were not trained athletes, and evaluating effects of HIIT or SIT on FatOx (vs no exercise or MICT) were included. RESULTS: Eighteen studies of fair-to-good quality were included; nine comparing HIIT or SIT with no exercise and eleven comparing HIIT or SIT with MICT. A significant pooled effect of these types of interval training on FatOx was found (mean difference in g/min (MD)=0.08; 95% confidence interval (CI) 0.04 to 0.12; p<0.001). Significant effects were found for exercise regimens lasting ≥4 weeks, and they increased with every additional week of training (ß=0.01; 95% CI 0.00 to 0.02; p=0.003). HIIT and/or SIT were slightly more effective than MICT (MD=0.03; 95% CI 0.01 to 0.05; p=0.005). The effects on FatOx were larger among individuals with overweight/obesity. CONCLUSION: Engaging in HIIT or SIT can improve FatOx, with larger effects expected for longer training regimens and individuals with overweight/obesity. While some effects seem small, they may be important in holistic approaches to enhance metabolic health and manage obesity.

A comprehensive assessment of caffeine's effects on components of countermovement jump performance.

The aim of this study was to conduct a comprehensive examination of caffeine's effects on countermovement jump (CMJ) performance. In this randomized, double-blind, crossover study, twenty-two resistance-trained men (age: 28 ± 5 years; height: 183 ± 5 cm; weight: 79 ± 10 kg; habitual caffeine intake: 127 ± 102 mg/day) performed the CMJ test on two occasions, following the ingestion of capsule containing 3 mg/kg of caffeine or placebo (3 mg/kg of dextrose). Fifteen outcomes derived from the force plate during the CMJ test were analyzed. As compared to placebo, there was a significant ergogenic effect of caffeine for peak force, force at eccentric to concentric action transition, time to peak force, peak power, maximum rate of power development, peak velocity, power at peak force, velocity at peak power, velocity at peak force, and vertical jump height. Effect sizes ranged from 0.11 to 0.38, p-values ranged from 0.048 to 0.002. There were no significant differences between caffeine and placebo for mean force, mean power, time to peak power, impulse at 300 ms, and force at peak power. This study shows that caffeine ingestion impacts a wide array of outcomes derived from the force plate during the CMJ test, not only jump height. From a practical perspective, the findings suggest that: (1) individuals interested in acute increases in CMJ performance may consider caffeine supplementation; and, (2) caffeine intake should be standardized before CMJ testing.

Test-retest reliability of isometric mid-thigh pull maximum strength assessment: a systematic review.

The aim of this systematic review was to explore the test-retest reliability of isometric mid-thigh pull maximum strength assessment. We searched through five databases to find studies that examined the test-retest reliability of peak force in the isometric mid-thigh pull exercise. From each included study, we extracted intra-class correlation coefficients (ICC) and/or coefficient of variation (CV). The methodological quality of the included studies was evaluated using the COSMIN checklist. A total of 16 good-to-excellent quality studies were included in the review. When considering results from all included studies, ICCs ranged from 0.73 to 0.99 (median ICC = 0.96), where 78% of ICCs were ≥ 0.90, and 98% of ICCs were ≥ 0.75. The range of reported CVs was from 0.7% to 11.1% (median CV = 4.9%), where 58% of CVs were ≤ 5%. Reliability was also good-to-excellent for both relative and absolute peak force and for both bilateral and unilateral isometric mid-thigh pull tests. The majority of studies did not find significant differences between testing sessions. It can be concluded that the isometric mid-thigh pull maximum strength assessment has good-to-excellent test-retest reliability. The isometric mid-thigh pull maximum strength assessment can be used as a reliable test in sports practice and for research purposes.

CYP1A2 genotype and acute ergogenic effects of caffeine intake on exercise performance: a systematic review.

PURPOSE: To systematically review studies that examined the influence of the CYP1A2 -163C>A polymorphism on the ergogenic effects of caffeine and to discuss some of the reasons for the discrepancies in findings between the studies. METHODS: This review was performed in accordance with the PRISMA guidelines. The search for studies was performed through nine databases. RESULTS: Seventeen studies were included in the review. Based on the included studies, it seems that individuals with the AA or AC/CC genotype may experience an increase in performance following caffeine ingestion. Significant differences between genotypes were found in four studies, and all four reported a more favorable response in the AA vs. AC/CC genotype. These results suggest that if there is an actual genotype-related effect of acute caffeine supplementation, it might be in that direction. In the studies that reported such data for aerobic endurance, the findings are specific to male participants performing cycling time trials (distances of ≥ 10 km) and ingesting caffeine 60 min before exercise. For high-intensity exercise, two studies reported that genotype variations determined the response to caffeine ingestion, even though the differences were either small (~ 1 additional repetition in high-load resistance exercise set performed to muscular failure) or inconsistent (i.e., observed only in one out of eight performance tests). CONCLUSIONS: CYP1A2 genotype variations may modulate caffeine's ergogenic effects, but the differences between genotypes were small, inconsistent, or limited to specific exercise scenarios. Future studies with larger sample sizes are needed to fully elucidate this research area.

Wake up and smell the coffee: caffeine supplementation and exercise performance-an umbrella review of 21 published meta-analyses.

OBJECTIVE: To systematically review, summarise and appraise findings of published meta-analyses that examined the effects of caffeine on exercise performance. DESIGN: Umbrella review. DATA SOURCES: Twelve databases. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Meta-analyses that examined the effects of caffeine ingestion on exercise performance. RESULTS: Eleven reviews (with a total of 21 meta-analyses) were included, all being of moderate or high methodological quality (assessed using the Assessing the Methodological Quality of Systematic Reviews 2 checklist). In the meta-analyses, caffeine was ergogenic for aerobic endurance, muscle strength, muscle endurance, power, jumping performance and exercise speed. However, not all analyses provided a definite direction for the effect of caffeine when considering the 95% prediction interval. Using the Grading of Recommendations Assessment, Development and Evaluation criteria the quality of evidence was generally categorised as moderate (with some low to very low quality of evidence). Most individual studies included in the published meta-analyses were conducted among young men. SUMMARY/CONCLUSION: Synthesis of the currently available meta-analyses suggest that caffeine ingestion improves exercise performance in a broad range of exercise tasks. Ergogenic effects of caffeine on muscle endurance, muscle strength, anaerobic power and aerobic endurance were substantiated by moderate quality of evidence coming from moderate-to-high quality systematic reviews. For other outcomes, we found moderate quality reviews that presented evidence of very low or low quality. It seems that the magnitude of the effect of caffeine is generally greater for aerobic as compared with anaerobic exercise. More primary studies should be conducted among women, middle-aged and older adults to improve the generalisability of these findings.

Is running associated with a lower risk of all-cause, cardiovascular and cancer mortality, and is the more the better? A systematic review and meta-analysis.

OBJECTIVE: To investigate the association of running participation and the dose of running with the risk of all-cause, cardiovascular and cancer mortality. DESIGN: Systematic review and meta-analysis. DATA SOURCES: Journal articles, conference papers and doctoral theses indexed in Academic Search Ultimate, CINAHL, Health Source: Nursing/Academic Edition, MasterFILE Complete, Networked Digital Library of Theses and Dissertations, Open Access Theses and Dissertations, PsycINFO, PubMed/MEDLINE, Scopus, SPORTDiscus and Web of Science. ELIGIBILITY CRITERIA FOR SELECTING STUDIES: Prospective cohort studies on the association between running or jogging participation and the risk of all-cause, cardiovascular and/or cancer mortality in a non-clinical population of adults were included. RESULTS: Fourteen studies from six prospective cohorts with a pooled sample of 232 149 participants were included. In total, 25 951 deaths were recorded during 5.5-35 year follow-ups. Our meta-analysis showed that running participation is associated with 27%, 30% and 23% lower risk of all-cause (pooled adjusted hazard ratio (HR)=0.73; 95% confidence interval (CI) 0.68 to 0.79), cardiovascular (HR=0.70; 95% CI 0.49 to 0.98) and cancer (HR=0.77; 95% CI 0.68 to 0.87) mortality, respectively, compared with no running. A meta-regression analysis showed no significant dose-response trends for weekly frequency, weekly duration, pace and the total volume of running. CONCLUSION: Increased rates of participation in running, regardless of its dose, would probably lead to substantial improvements in population health and longevity. Any amount of running, even just once a week, is better than no running, but higher doses of running may not necessarily be associated with greater mortality benefits.

Is Coffee a Useful Source of Caffeine Preexercise?

Caffeine is a well-established ergogenic aid, with its performance-enhancing effects demonstrated across a wide variety of exercise modalities. Athletes tend to frequently consume caffeine as a performance enhancement method in training and competition. There are a number of methods available as a means of consuming caffeine around exercise, including caffeine anhydrous, sports drinks, caffeine carbohydrate gels, and gum. One popular method of caffeine ingestion in nonathletes is coffee, with some evidence suggesting it is also utilized by athletes. In this article, we discuss the research pertaining to the use of coffee as an ergogenic aid, exploring (a) whether caffeinated coffee is ergogenic, (b) whether dose-matched caffeinated coffee provides a performance benefit similar in magnitude to caffeine anhydrous, and (c) whether decaffeinated coffee consumption affects the ergogenic effects of a subsequent isolated caffeine dose. There is limited evidence that caffeinated coffee has the potential to offer ergogenic effects similar in magnitude to caffeine anhydrous; however, this requires further investigation. Coingestion of caffeine with decaffeinated coffee does not seem to limit the ergogenic effects of caffeine. Although caffeinated coffee is potentially ergogenic, its use as a preexercise caffeine ingestion method represents some practical hurdles to athletes, including the consumption of large volumes of liquid and difficulties in quantifying the exact caffeine dose, as differences in coffee type and brewing method may alter caffeine content. The use of caffeinated coffee around exercise has the potential to enhance performance, but athletes and coaches should be mindful of the practical limitations.

Alterations in Body Composition, Resting Metabolic Rate, Muscular Strength, and Eating Behavior in Response to Natural Bodybuilding Competition Preparation: A Case Study.

Schoenfeld, BJ, Alto, A, Grgic, J, Tinsley, G, Haun, CT, Campbell, BI, Escalante, G, Sonmez, GT, Cote, G, Francis, A, and Trexler, ET. Alterations in body composition, resting metabolic rate, muscular strength, and eating behavior in response to natural bodybuilding competition preparation: A case study. J Strength Cond Res 34(11): 3124-3138, 2020-We carried out a prospective case study in a high-level amateur natural male bodybuilder throughout preparation for 4 competitions and during the ensuing postcontest recovery period. Laboratory testing was conducted monthly over a 1-year period, which included the following assessments: B-mode ultrasound evaluation of muscle thickness (MT), multifrequency bioelectrical impedance analysis, blood pressure and heart rate assessment, resting metabolic rate via indirect calorimetry, skinfold testing, vertical jump height, isometric lower-body strength testing, and a 3-factor eating questionnaire. Blood work (including testosterone, thyroid hormone, sex hormone binding globulin, glomerular filtration rate, blood urea nitrogen, aspartate aminotransferase, alanine aminotransferase, white blood count, albumin to globulin ratio, and lipoprotein A) was obtained separately from an outside laboratory at 4 time points. We also assessed the effectiveness of a carbohydrate (carb) deplete and carb load peaking strategy employed immediately before competition. The subject employed a high-volume, high-frequency, whole-body training program throughout the study period. Average daily nutritional intakes ranged from 1,953 to 3,415 kcal: 104-386 g carb; 253-263 g protein, and; 57-95 g lipid. Body fat was reduced to very low levels (∼5%) immediately before competition, but this corresponded with a loss of lean mass. Alterations in metabolism, hormonal status, explosive strength, and psychological aspects of eating were observed during precontest preparation; however, all of these variables recovered quickly postcompetition. The implementation of a carb depleteand carb load peaking strategy acutely increased MT and thus may be a viable precontest approach to maximize muscular aesthetics.

Effectiveness of interventions for reducing non-occupational sedentary behaviour in adults and older adults: a systematic review and meta-analysis.

BACKGROUND: No systematic reviews of the effectiveness of interventions for reducing non-occupational sedentary behaviour are available. Therefore, the aim of this systematic review was to assess the effectiveness of interventions for reducing non-occupational sedentary behaviour in adults and older adults. METHODS: An electronic search of nine databases was performed. Randomised controlled trials (RCT) and cluster RCTs among adults testing the effectiveness of interventions aimed to reduce non-occupational sedentary behaviour were considered for inclusion. Two review authors independently screened studies for eligibility, completed data extraction and assessed the risk of bias. RESULTS: Nineteen studies that evaluated multicomponent lifestyle interventions, counselling or education, television (TV) control devices and workplace interventions were included. Evidence from the meta-analyses suggested that interventions can reduce leisure sitting time in adults in the medium term (-30 min/day; 95% CI -58 to -2), and TV viewing in the short term (-61 min/day; 95% CI -79 to -43) and medium term (-11 min/day; 95% CI -20 to -2). No significant pooled effects were found for transport sitting time, leisure-time computer use and longer term outcomes. No evidence was available on the effectiveness of interventions for reducing non-occupational sedentary time in older adults. CONCLUSIONS: The findings of this systematic review suggest the interventions may be effective in reducing non-occupational sedentary behaviour in the short to medium term in adults. However, no significant effect was found on longer term outcomes. The quality of evidence was, however, low to very low. No evidence was available on the effectiveness of non-occupational interventions on reducing sedentary time in older adults. Further high-quality research with larger samples is warranted.

How many times per week should a muscle be trained to maximize muscle hypertrophy? A systematic review and meta-analysis of studies examining the effects of resistance training frequency.

Training frequency is considered an important variable in the hypertrophic response to regimented resistance exercise. The purpose of this paper was to conduct a systematic review and meta-analysis of experimental studies designed to investigate the effects of weekly training frequency on hypertrophic adaptations. Following a systematic search of PubMed/MEDLINE, Scoups, and SPORTDiscus databases, a total of 25 studies were deemed to meet inclusion criteria. Results showed no significant difference between higher and lower frequency on a volume-equated basis. Moreover, no significant differences were seen between frequencies of training across all categories when taking into account direct measures of growth, in those considered resistance-trained, and when segmenting into training for the upper body and lower body. Meta-regression analysis of non-volume-equated studies showed a significant effect favoring higher frequencies, although the overall difference in magnitude of effect between frequencies of 1 and 3+ days per week was modest. In conclusion, there is strong evidence that resistance training frequency does not significantly or meaningfully impact muscle hypertrophy when volume is equated. Thus, for a given training volume, individuals can choose a weekly frequency per muscle groups based on personal preference.

Effect of Interset Strategies on Acute Resistance Training Performance and Physiological Responses: A Systematic Review.

Latella, C, Grgic, J, and Van der Westhuizen, D. Effect of interset strategies on acute resistance training performance and physiological responses: a systematic review. J Strength Cond Res XX(X): 000-000, 2019-The purpose of this systematic review was to evaluate the evidence surrounding the implementation of interset strategies to optimize acute resistance training performance. Searches of PubMed/MEDLINE, Scopus, and SPORTDiscus electronic databases were conducted. Studies that met the following criteria were included: (a) compared an interset strategy with a traditional passive rest interval in resistance training, (b) the assessed outcomes included performance or physiological responses, (c) resistance training was performed in a traditional dynamic fashion, (d) the study had an acute design, and (e) was published in English and in a peer-reviewed journal. A total of 26 studies were included in the review. When a given interset strategy was used, several studies reported improvements in the number of performed repetitions (i.e., greater total volume load), attenuation of the loss in velocity and power, reduced lactate levels, and in some cases, a decrease in perceived exertion. Dynamic agonist/static antagonist stretching, cooling, aerobic exercise, vibration, and individualized heart rate-based intervals seem to be the most effective strategies. However, the heterogeneity between study designs and methodologies suggests that careful consideration should be given to the type and specific application of the interset method being used. Given the acute nature of studies, extrapolation to any long-term benefits of using a given interset strategy remains limited. Collectively, coaches and sports scientists may consider using the most effective strategies based on practicality and equipment availability to optimize performance during the resistance training component of strength and conditioning programs.

Resistance Training Frequencies of 3 and 6 Times Per Week Produce Similar Muscular Adaptations in Resistance-Trained Men.

Saric, J, Lisica, D, Orlic, I, Grgic, J, Krieger, JW, Vuk, S, and Schoenfeld, BJ. Resistance training frequencies of 3 and 6 times per week produce similar muscular adaptations in resistance-trained men. J Strength Cond Res 33(7S): S122-S129, 2019-We examined the effects of resistance training (RT) frequency performed 3 times per week (RT3) vs. RT performed 6 times per week (RT6) under volume-equated conditions in resistance-trained men. Twenty-seven men were randomly allocated to RT3 (n = 14) or RT6 (n = 13). The supervised training intervention lasted for 6 weeks. Upper- and lower-body strength were assessed using the 1 repetition maximum test. Also, muscular endurance (60% 1 repetition maximum performed to momentary failure) and muscle thickness (elbow flexors, elbow extensors, rectus femoris, and vastus intermedius) were measured before and after intervention. Pre-to-post intervention, both groups increased upper-body strength (RT3: +4%; RT6: +6%) and lower-body strength (RT3: +22%; RT6: +18%) with no significant between-group differences. No significant pre-to-post intervention increases in muscular endurance were seen in either of the training groups. Both groups increased elbow extensor thickness (RT3: +14%; RT6: +11%), rectus femoris thickness (RT3: +5%; RT6: +6%), and vastus intermedius thickness (RT3: +10%; RT6: +11%) with no significant between-group differences. Only the RT3 group significantly increased elbow flexor thickness from pre-to-post intervention (+7%). When training volume is equated, it seems that RT performed either 3 or 6 times per week can result in similar strength gains over a 6-week training period. Furthermore, under volume-equated conditions, comparable hypertrophy results may also be expected with both RT frequencies. Finally, no changes were seen in muscular endurance possibly because of the considerable interindividual variability in responses. The findings presented herein might be of interest to coaches, exercise practitioners, athletes, and recreational trainees.

Health outcomes associated with reallocations of time between sleep, sedentary behaviour, and physical activity: a systematic scoping review of isotemporal substitution studies.

BACKGROUND: During a 24-h day, each given period is spent in either sedentary behaviour, sleeping, light physical activity (LPA), or moderate-to-vigorous physical activity (MVPA). In epidemiological research most studies have traditionally analysed the associations of these behaviours in isolation from each other; that is, without taking into account the displacement of time spent in the remaining behaviours. In recent years, there has been a growing interest in exploring how all the behaviours across the energy expenditure spectrum influence health outcomes. A statistical model used to investigate these associations is termed an isotemporal substitution model (ISM). Considering the increasing number of ISM-based studies conducted in all age groups, the present paper aimed to: (i) review and summarise findings from studies that employed ISM in sleep, sedentary behaviour, and physical activity research; (ii) appraise the methodological quality of the studies; and (iii) suggest future research directions in this area. METHODS: A systematic search of ten databases was performed. The Newcastle-Ottawa scale was used to assess the methodological quality of the included studies. RESULTS: Fifty-six studies met the inclusion criteria, all being of moderate or high methodological quality. Associations were reported for exchanged time varying from one minute to 120 min/day across the studies, with 30 min/day being the most common amount of time reallocated. In total, three different ISM methodologies were used. The most commonly studied health outcomes in relation to isotemporal substitutions were mortality, general health, mental health, adiposity, fitness, and cardiometabolic biomarkers. It seems that reallocations of sedentary time to LPA or MVPA are associated with significant reduction in mortality risk. Current evidence appears to consistently suggest that reductions in mortality risk are greater when time spent sedentary is replaced with higher intensities of physical activity. For adiposity, it seems that reallocating sedentary time to physical activity may be associated with reduced body mass index, body fat percentage, and waist circumference in all age groups, with the magnitude of associations being greater for higher intensities of physical activity. While there is a relatively large body of evidence reporting beneficial associations between the reallocation of time from sedentary behaviour to LPA or MVPA and cardiometabolic biomarkers among adults, there is a lack of studies among children, adolescents, and older adults. Although some studies investigated general health, mental health, and fitness outcomes, further investigation of these topics is warranted. In general, it seems that the strongest association with health outcomes is observed when time is reallocated from sedentary behaviour to MVPA. Most studies did not account for sleep time, which is a major limitation of the current evidence. CONCLUSIONS: The current evidence indicates that time reallocation between sleep, sedentary behaviour, LPA, and MVPA may be associated with a number of health outcomes. Future studies should employ longitudinal designs, take into account all movement behaviours, and examine a wider range of health, psychological, social, economic, and environmental outcomes.

Tapering Practices of Croatian Open-Class Powerlifting Champions.

Grgic, J and Mikulic, P. Tapering practices of Croatian open-class powerlifting champions. J Strength Cond Res 31(9): 2371-2378, 2017-The aim of this study was to explore tapering practices among 10 Croatian open-class powerlifting champions (mean ± SD: age 29.2 ± 3.2 years; Wilks coefficient 355.1 ± 54.8). The athletes were interviewed about their tapering practices using a semi-structured interview after which the audio content was transcribed. The athletes reported decreasing training volume during the taper by 50.5 ± 11.7% using a step type or an exponential type of taper with a fast decay. Training intensity was maintained or increased during the taper, and it reached its highest values 8 ± 3 days before the competition. Training frequency was reduced or maintained during the taper. The final week included a reduction in training frequency by 47.9 ± 17.5% with the last training session performed 3 ± 1 days before the competition. The participants typically stated that the main reasons for conducting the taper were maintaining strength and reducing the amount of fatigue. They also stated that (a) the taper was structured identically for the squat, bench press, and the deadlift; (b) the training during the taper was highly specific, the assistance exercises were removed, and the same equipment was used as during competition; (c) the source of information for tapering was their coach, and training fluctuated based on the coach's feedback; and (d) nutrition, foam rolling, static stretching, and massage were all given extra attention during the taper. These results may aid athletes and coaches in strength sports in terms of the optimization of tapering variables.