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Wu W, Chen Z, Zhou H, Wang L, Li X, Lv Y, Sun T, Yu L. Effects of Acute Ingestion of Caffeine Capsules on Muscle Strength and Muscle Endurance: A Systematic Review and Meta-Analysis. Nutrients 2024; 16:1146. [PMID: 38674836 PMCID: PMC11054210 DOI: 10.3390/nu16081146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 04/07/2024] [Accepted: 04/10/2024] [Indexed: 04/28/2024] Open
Abstract
This study aimed to explore the effects of acute ingestion of caffeine capsules on muscle strength and muscle endurance. We searched the PubMed, Web of Science, Cochrane, Scopus, and EBSCO databases. Data were pooled using the weighted mean difference (WMD) and 95% confidence interval. Fourteen studies fulfilled the inclusion criteria. The acute ingestion of caffeine capsules significantly improved muscle strength (WMD, 7.09, p < 0.00001) and muscle endurance (WMD, 1.37; p < 0.00001), especially in males (muscle strength, WMD, 7.59, p < 0.00001; muscle endurance, WMD, 1.40, p < 0.00001). Subgroup analyses showed that ≥ 6 mg/kg body weight of caffeine (WMD, 6.35, p < 0.00001) and ingesting caffeine 45 min pre-exercise (WMD, 8.61, p < 0.00001) were more effective in improving muscle strength, with the acute ingestion of caffeine capsules having a greater effect on lower body muscle strength (WMD, 10.19, p < 0.00001). In addition, the acute ingestion of caffeine capsules had a greater effect in moderate-intensity muscle endurance tests (WMD, 1.76, p < 0.00001). An acute ingestion of caffeine capsules significantly improved muscle strength and muscle endurance in the upper body and lower body of males.
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Affiliation(s)
- Weiliang Wu
- Key Laboratory of Physical Fitness and Exercise, Ministry of Education, Beijing Sport University, Beijing 100084, China;
- Department of Strength and Conditioning Assessment and Monitoring, Beijing Sport University, Beijing 100084, China; (Z.C.); (L.W.); (X.L.)
| | - Zhizhou Chen
- Department of Strength and Conditioning Assessment and Monitoring, Beijing Sport University, Beijing 100084, China; (Z.C.); (L.W.); (X.L.)
| | - Huixuan Zhou
- School of Sport Sciences, Beijing Sport University, Beijing 100084, China;
| | - Leiyuyang Wang
- Department of Strength and Conditioning Assessment and Monitoring, Beijing Sport University, Beijing 100084, China; (Z.C.); (L.W.); (X.L.)
| | - Xiang Li
- Department of Strength and Conditioning Assessment and Monitoring, Beijing Sport University, Beijing 100084, China; (Z.C.); (L.W.); (X.L.)
| | - Yuanyuan Lv
- China Institute of Sport and Health Science, Beijing Sport University, Beijing 100084, China;
| | - Tingting Sun
- Key Laboratory of Physical Fitness and Exercise, Ministry of Education, Beijing Sport University, Beijing 100084, China;
| | - Laikang Yu
- Key Laboratory of Physical Fitness and Exercise, Ministry of Education, Beijing Sport University, Beijing 100084, China;
- Department of Strength and Conditioning Assessment and Monitoring, Beijing Sport University, Beijing 100084, China; (Z.C.); (L.W.); (X.L.)
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Grgic J, Varovic D. Moderators of Caffeine's Effects on Jumping Performance in Females: A Systematic Review and Meta-Analysis. JOURNAL OF THE AMERICAN NUTRITION ASSOCIATION 2024; 43:92-100. [PMID: 37191618 DOI: 10.1080/27697061.2023.2212740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 05/07/2023] [Indexed: 05/17/2023]
Abstract
We aimed to perform a systematic review and meta-analysis of caffeine's effects on vertical jumping performance in females, with subgroup analyses for potential moderators, including phase of the menstrual cycle, testing time of day, caffeine dose, and test type. Fifteen studies were included in the review (n = 197). Their data were pooled in a random-effects meta-analysis of effect sizes (Hedges' g). In the main meta-analysis, we found an ergogenic effect of caffeine on jumping performance (g: 0.28). An ergogenic effect of caffeine on jumping performance was found when the testing was carried out in the luteal phase (g: 0.24), follicular phase (g: 0.52), luteal or follicular phase (g: 0.31), and when the phase was not specified (g: 0.21). The test for subgroup differences indicated that the ergogenic effects of caffeine were significantly greater in the follicular phase compared to all other conditions. An ergogenic effect of caffeine on jumping performance was found when the testing was carried out in the morning (g: 0.38), evening (g: 0.19), mixed morning or evening (g: 0.38), and when time was not specified (g: 0.32), with no subgroup differences. An ergogenic effect of caffeine on jumping performance was found when the dose was ≤3 mg/kg (g: 0.21), or >3 mg/kg (g: 0.37), with no subgroup differences. An ergogenic effect of caffeine on jumping performance was found in the countermovement jump test (g: 0.26) and squat jump test (g: 0.35), with no subgroup differences. In summary, caffeine ingestion is ergogenic for vertical jumping performance in females, and it seems that the magnitude of these effects is the largest in the follicular phase of the menstrual cycle.
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Affiliation(s)
- Jozo Grgic
- Institute for Health and Sport, Victoria University, Melbourne, Australia
| | - Dorian Varovic
- Faculty of Kinesiology, University of Zagreb, Zagreb, Croatia
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Rodriguez C, Stratton MT, Harty PS, Siedler MR, Boykin JR, Green JJ, Keith DS, White SJ, DeHaven B, Brojanac A, Tinoco E, Taylor LW, Tinsley GM. Effects of a ready-to-drink thermogenic beverage on resting energy expenditure, hemodynamic function, and subjective outcomes. J Int Soc Sports Nutr 2023; 20:2211958. [PMID: 37162193 PMCID: PMC10173796 DOI: 10.1080/15502783.2023.2211958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023] Open
Abstract
BACKGROUND Thermogenic supplements are often consumed by individuals seeking to improve energy levels and reduce body fat. These supplements are sold in powdered or ready-to-drink (RTD) forms and consist of a blend of ingredients such as caffeine, green tea extract, and other botanical compounds. While there is evidence that thermogenic supplements can positively affect resting energy expenditure (REE), the effect varies based on the combination of active ingredients. Additionally, there is some concern that thermogenic supplements may cause unwanted side effects on hemodynamic variables, like heart rate (HR) and blood pressure (BP). Therefore, further investigation into the efficacy and safety of commercially available products is warranted. METHODS Twenty-eight individuals (14 F, 14 M; age: 23.3 ± 3.9 yrs; height: 169.4 ± 8.6 cm; body mass: 73.3 ± 13.1 kg) completed two visits in a randomized, double-blind, crossover fashion. Each visit began with baseline REE, HR, and BP assessments, which were followed by ingestion of an active RTD thermogenic beverage (RTD; OxyShred Ultra Energy) or placebo (PL). Assessments were repeated at the intervals of 35-50- and 85-100-minutes post-ingestion. In addition, subjective outcomes of energy, focus, concentration, alertness, and mood were collected five times throughout each visit. Repeated-measures analysis of variance was performed with condition and time specified as within-subjects factors and sex and resistance training (RT) status as between-subjects factors. Statistical significance was accepted at p < 0.05. RESULTS A significant condition × time interaction was observed for REE (p < 0.001). Higher REE values were demonstrated at 35-50 min (0.08 ± 0.02 kcal/min; p = 0.001; 5.2% difference) and 85-100 min (0.08 ± 0.02 kcal/min; p = 0.001; 5.5% difference) after RTD ingestion as compared to PL. No significant condition × time interactions were observed for respiratory quotient, HR, or BP. Condition main effects indicated lower HR (3.0 ± 0.9 bpm; p = 0.003), higher SBP (3.5 ± 1.1 mm Hg; p = 0.003) and higher DBP (3.5 ± 0.9 mm Hg; p < 0.001) in RTD as compared to PL, irrespective of time. Condition × time interactions were observed for all subjective outcomes (p ≤ 0.02). Post hoc tests indicated statistically significant benefits of the RTD over PL for energy, focus, concentration, and alertness, without significant differences for mood after correction for multiple comparisons. Sex and RT status were not involved in interactions for any outcomes, except for a Sex × RT status interaction for energy, indicating higher energy ratings in non-resistance-trained vs. resistance-trained males. CONCLUSIONS These data suggest that acute ingestion of a thermogenic RTD beverage significantly increases REE, and this elevated caloric expenditure is sustained for at least 100 minutes following ingestion. Furthermore, the RTD beverage increased measures of energy, focus, concentration, and alertness as compared to placebo. While minor differences in hemodynamic variables were observed between conditions, all values stayed within normal ranges. Individuals aiming to increase energy expenditure may benefit from acute ingestion of an RTD thermogenic supplement.
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Affiliation(s)
- Christian Rodriguez
- Texas Tech University, Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Lubbock, TX, USA
| | - Matthew T Stratton
- Texas Tech University, Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Lubbock, TX, USA
| | - Patrick S Harty
- Texas Tech University, Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Lubbock, TX, USA
| | - Madelin R Siedler
- Texas Tech University, Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Lubbock, TX, USA
| | - Jake R Boykin
- Texas Tech University, Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Lubbock, TX, USA
| | - Jacob J Green
- Texas Tech University, Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Lubbock, TX, USA
| | - Dale S Keith
- Texas Tech University, Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Lubbock, TX, USA
| | - Sarah J White
- Texas Tech University, Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Lubbock, TX, USA
| | - Brielle DeHaven
- Texas Tech University, Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Lubbock, TX, USA
| | - Alexandra Brojanac
- Texas Tech University, Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Lubbock, TX, USA
| | - Ethan Tinoco
- Texas Tech University, Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Lubbock, TX, USA
| | - Lem W Taylor
- University of Mary Hardin-Baylor, Human Performance Laboratory, School of Exercise and Sport Science, Belton, TX, USA
| | - Grant M Tinsley
- Texas Tech University, Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Lubbock, TX, USA
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Kerksick CM, Pugh JN. Editorial: Pre-workout nutrition. Front Sports Act Living 2023; 5:1257740. [PMID: 37547822 PMCID: PMC10402752 DOI: 10.3389/fspor.2023.1257740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 07/13/2023] [Indexed: 08/08/2023] Open
Affiliation(s)
- Chad M. Kerksick
- Exercise and Performance Nutrition Laboratory, College of Science, Technology, and Health, Lindenwood University, St. Charles, MO, United States
| | - Jamie N. Pugh
- Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Liverpool, United Kingdom
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López-Torres O, Rodríguez-Longobardo C, Capel-Escoriza R, Fernández-Elías VE. Ergogenic Aids to Improve Physical Performance in Female Athletes: A Systematic Review with Meta-Analysis. Nutrients 2022; 15:nu15010081. [PMID: 36615738 PMCID: PMC9823656 DOI: 10.3390/nu15010081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2022] [Revised: 12/17/2022] [Accepted: 12/20/2022] [Indexed: 12/29/2022] Open
Abstract
Most intervention studies investigating the effects of ergogenic aids (EAs) on sports performance have been carried out in the male population. Thus, the aim of this systematic review and meta-analysis was to summarize the effects in the existing literature of EAs used by female athletes on performance. A literature research was conducted, and a descriptive analysis of the articles included in the systematic review was carried out. Meta-analyses could be performed on 32 of the included articles, evaluating performance in strength, sprint, and cardiovascular capacity. A random-effects model and the standardized mean differences (SMD) ± 95% confidence intervals (CI) were reported. The results showed that caffeine helped to improve jumping performance, isometric strength values, and the number of repetitions until failure. Caffeine and sodium phosphate helped to improve sprint performance. Aerobic tests could be improved with the use of taurine, caffeine, and beta-alanine. No conclusive effects of beetroot juice, polyphenols, or creatine in improving aerobic performance were shown. In terms of anaerobic variables, both caffeine and sodium phosphate could help to improve repeated sprint ability. More studies are needed in female athletes that measure the effects of different EAs on sports performance, such as beetroot juice, beta-alanine or sodium phosphate, as the studies to date are scarce and there are many types of EA that need to be further considered in this population, such as creatine and taurine.
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Affiliation(s)
- Olga López-Torres
- Faculty of Sport Sciences, Universidad Europea de Madrid, 28670 Madrid, Spain
| | - Celia Rodríguez-Longobardo
- Social Sciences of Physical Activity, Sport and Leisure Department, Faculty of Physical Activity and Sport Sciences, Universidad Politécnica de Madrid, 28040 Madrid, Spain
- Correspondence:
| | - Raquel Capel-Escoriza
- Faculty of Sport Sciences, Universidad Europea de Madrid, 28670 Madrid, Spain
- Raquel Wellness Instituto de Nutrición y Salud, 28050 Madrid, Spain
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Tamilio RA, Clarke ND, Duncan MJ, Morris RO, Tallis J. How Repeatable Is the Ergogenic Effect of Caffeine? Limited Reproducibility of Acute Caffeine (3 mg.kg -1) Ingestion on Muscular Strength, Power, and Muscular Endurance. Nutrients 2022; 14:nu14204416. [PMID: 36297102 PMCID: PMC9611362 DOI: 10.3390/nu14204416] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 10/17/2022] [Accepted: 10/19/2022] [Indexed: 11/16/2022] Open
Abstract
This study aimed to determine the effect of 3 mg.kg−1 acute caffeine ingestion on muscular strength, power and strength endurance and the repeatability of potential ergogenic effects across multiple trials. Twenty-two university standard male rugby union players (20 ± 2 years) completed the study. Using a double-blind, randomized, and counterbalanced within-subject experimental design. Participants completed six experimental trials (three caffeine and three placebo) where force time characteristic of the Isometric Mid-Thigh Pull (IMTP), Countermovement Jump (CMJ) and Drop Jumps (DJ) were assessed followed by assessments of Chest Press (CP), Shoulder Press (SP), Squats (SQ), and Deadlifts (DL) Repetitions Until Failure (RTF at 70% 1 RM). ANOVA indicated that caffeine improved both the CMJ and DJ (p < 0.044) and increased RTF in all RTF assessments (p < 0.002). When individual caffeine trials were compared to corresponding placebo trials, effect sizes ranged from trivial-large favoring caffeine irrespective of a main effect of treatment being identified in the ANOVA. These results demonstrate for the first time that the performance enhancing effects of caffeine may not be repeatable between days, where our data uniquely indicates that this is in part attributable to between sessions variation in caffeine’s ergogenic potential.
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Kaufman MW, Roche M, Fredericson M. The Impact of Supplements on Sports Performance for the Trained Athlete: A Critical Analysis. Curr Sports Med Rep 2022; 21:232-238. [PMID: 35801724 DOI: 10.1249/jsr.0000000000000972] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
ABSTRACT Elite athletes often use nutritional supplements to improve performance and gain competitive advantage. The prevalence of nutrient supplementation ranges from 40% to 100% among trained athletes, yet few athletes have a trusted source of information for their supplement decisions and expected results. This critical analysis review evaluates systematic reviews, meta-analyses, randomized control trials, and crossover trials investigating commonly used supplements in sport: caffeine, creatine, beta-alanine (β-alanine), branched chain amino acids (BCAAs), and dietary nitrates. By reviewing these supplements' mechanisms, evidence relating directly to improving sports performance, and ideal dosing strategies, we provide a reference for athletes and medical staff to personalize supplementation strategies. Caffeine and creatine impact power and high-intensity athletes, β-alanine, and BCAA mitigate fatigue, and dietary nitrates improve endurance. With each athlete having different demands, goals to maximize their performance, athletes and medical staff should collaborate to personalize supplementation strategies based on scientific backing to set expectations and potentiate results.
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Affiliation(s)
- Matthew W Kaufman
- Department of Orthopedic Surgery, Case Western Reserve University, Cleveland, OH
| | - Megan Roche
- Department of Orthopaedic Surgery, Stanford University, Redwood City, CA
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Kreutzer A, Graybeal AJ, Moss K, Braun-Trocchio R, Shah M. Caffeine Supplementation Strategies Among Endurance Athletes. Front Sports Act Living 2022; 4:821750. [PMID: 35463835 PMCID: PMC9030507 DOI: 10.3389/fspor.2022.821750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Accepted: 03/18/2022] [Indexed: 11/21/2022] Open
Abstract
Caffeine is widely accepted as an endurance-performance enhancing supplement. Most scientific research studies use doses of 3–6 mg/kg of caffeine 60 min prior to exercise based on pharmacokinetics. It is not well understood whether endurance athletes employ similar supplementation strategies in practice. The purpose of this study was to investigate caffeine supplementation protocols among endurance athletes. A survey conducted on Qualtrics returned responses regarding caffeine supplementation from 254 endurance athletes (f = 134, m =120; age = 39.4 ± 13.9 y; pro = 11, current collegiate athlete = 37, recreational = 206; running = 98, triathlon = 83, cycling = 54, other = 19; training days per week = 5.4 ± 1.3). Most participants reported habitual caffeine consumption (85.0%; 41.2% multiple times daily). However, only 24.0% used caffeine supplements. A greater proportion of men (31.7%) used caffeine supplements compared with women (17.2%; p = 0.007). Caffeine use was also more prevalent among professional (45.5%) and recreational athletes (25.1%) than in collegiate athletes (9.4%). Type of sport (p = 0.641), household income (p = 0.263), education (p = 0.570) or working with a coach (p = 0.612) did not have an impact on caffeine supplementation prevalence. Of those reporting specific timing of caffeine supplementation, 49.1% and 34.9% reported consuming caffeine within 30 min of training and races respectively; 38.6 and 36.5% used caffeine 30–60 min before training and races. Recreational athletes reported consuming smaller amounts of caffeine before training (1.6 ± 1.0 mg/kg) and races (2.0 ± 1.2 mg/kg) compared with collegiate (TRG: 2.1 ± 1.2 mg/kg; RACE: 3.6 ± 0.2 mg/kg) and professional (TRG: 2.4 ± 1.1 mg/kg; RACE: 3.5 ± 0.6 mg/kg) athletes. Overall, participants reported minor to moderate perceived effectiveness of caffeine supplementation (2.31 ± 0.9 on a four-point Likert-type scale) with greatest effectiveness during longer sessions (2.8 ± 1.1). It appears that recreational athletes use lower caffeine amounts than what has been established as ergogenic in laboratory protocols; further, they consume caffeine closer to exercise compared with typical research protocols. Thus, better education of recreational athletes and additional research into alternative supplementation strategies are warranted.
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Affiliation(s)
- Andreas Kreutzer
- Department of Kinesiology, Texas Christian University, Fort Worth, TX, United States
- *Correspondence: Andreas Kreutzer
| | - Austin J. Graybeal
- Department of Kinesiology, Texas Christian University, Fort Worth, TX, United States
- School of Kinesiology and Nutrition, College of Education and Human Sciences, University of Southern Mississippi, Hattiesburg, MS, United States
| | - Kamiah Moss
- Department of Kinesiology, Texas Christian University, Fort Worth, TX, United States
| | - Robyn Braun-Trocchio
- Department of Kinesiology, Texas Christian University, Fort Worth, TX, United States
| | - Meena Shah
- Department of Kinesiology, Texas Christian University, Fort Worth, TX, United States
- Meena Shah
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Stratton MT, Siedler MR, Harty PS, Rodriguez C, Boykin JR, Green JJ, Keith DS, White SJ, DeHaven B, Williams AD, Tinsley GM. The influence of caffeinated and non-caffeinated multi-ingredient pre-workout supplements on resistance exercise performance and subjective outcomes. J Int Soc Sports Nutr 2022; 19:126-149. [PMID: 35599920 PMCID: PMC9116396 DOI: 10.1080/15502783.2022.2060048] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Background There is substantial consumer and practitioner interest in an emerging supplement class known as multi-ingredient pre-workout supplements (MIPS), largely due to their prevalence in resistance training communities as well as research findings demonstrating the ergogenic impact of caffeine on muscular performance. However, limited research has examined the potential efficacy of non-caffeinated MIPS, despite their growing popularity among those who are caffeine-sensitive or who train later in the day. Methods Twenty-four resistance-trained college-aged males (n = 12) and females (n = 12) completed three visits in which they ingested either a caffeinated MIPS (C), an otherwise identical non-caffeinated MIPS (NC), or placebo in a double-blind, counterbalanced, crossover fashion. Squat isometric peak force (PFiso), rate of force development (RFD), and isokinetic performance were assessed. Upper and lower body maximal muscular strength and endurance were evaluated using the bench press and leg press, respectively. Visual analog scales for energy, focus, and fatigue were completed five times throughout the testing protocol. The effects of supplementation and biological sex on all variables were examined using linear mixed effects models. Results Significantly greater PFiso was observed in both C (b: 0.36 transformed units [0.09, 0.62]) and NC (b: 0.32 transformed units [95% CI: 0.05, 0.58]) conditions, relative to placebo. Early RFD (RFD50) may have been higher with supplementation, particularly in females, with no effects for late RFD (RFD200) or peak RFD. In addition, increases in subjective energy after supplement ingestion were noted for C, but not NC. No effects of supplementation on traditional resistance exercise performance or isokinetic squat performance were observed, other than a lower leg press one-repetition maximum for males in the NC condition. Conclusions These data indicate that acute ingestion of either a caffeinated or non-caffeinated pre-workout formulation improved maximal force production during an isometric squat test but did not provide additional benefit to leg press, bench press, or isokinetic squat performance over placebo, within the context of a laboratory environment. The consumption of a caffeinated, but not non-caffeinated, MIPS increased subjective ratings of energy over placebo when assessed as part of a testing battery.
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Affiliation(s)
- Matthew T. Stratton
- Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Madelin R. Siedler
- Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Patrick S. Harty
- Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Christian Rodriguez
- Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Jake R. Boykin
- Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Jacob J. Green
- Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Dale S. Keith
- Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Sarah J. White
- Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Brielle DeHaven
- Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Abegale D. Williams
- Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
| | - Grant M. Tinsley
- Energy Balance & Body Composition Laboratory; Department of Kinesiology & Sport Management, Texas Tech University, Lubbock, TX, USA
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Effects of Caffeine on Resistance Exercise: A Review of Recent Research. Sports Med 2021; 51:2281-2298. [PMID: 34291426 DOI: 10.1007/s40279-021-01521-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/07/2021] [Indexed: 02/06/2023]
Abstract
In the last few years, a plethora of studies have explored the effects of caffeine on resistance exercise, demonstrating that this field of research is growing fast. This review evaluates and summarizes the most recent findings. Given that toxic doses of caffeine are needed to increase skeletal muscle contractility, the binding of caffeine to adenosine receptors is likely the primary mechanism for caffeine's ergogenic effects on resistance exercise. There is convincing evidence that caffeine ingestion is ergogenic for (i) one-repetition maximum, isometric, and isokinetic strength; and (ii) muscular endurance, velocity, and power in different resistance exercises, loads, and set protocols. Furthermore, there is some evidence that caffeine supplementation also may enhance adaptations to resistance training, such as gains in strength and power. Caffeine ingestion is ergogenic for resistance exercise performance in females, and the magnitude of these effects seems to be similar to that observed in men. Habitual caffeine intake and polymorphisms within CYP1A2 and ADORA2A do not seem to modulate caffeine's ergogenic effects on resistance exercise. Consuming lower doses of caffeine (e.g., 2-3 mg/kg) appears to be comparably ergogenic to consuming high doses of caffeine (e.g., 6 mg/kg). Minimal effective doses of caffeine seem to be around 1.5 mg/kg. Alternate caffeine sources such as caffeinated chewing gum, gel, and coffee are also ergogenic for resistance exercise performance. With caffeine capsules, the optimal timing of ingestion seems to be 30-60 min before exercise. Caffeinated chewing gums and gels may enhance resistance exercise performance even when consumed 10 min before exercise. It appears that caffeine improves performance in resistance exercise primarily due to its physiological effects. Nevertheless, a small portion of the ergogenic effect of caffeine seems to be placebo-driven.
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Selected Literature Watch. J Caffeine Adenosine Res 2021. [DOI: 10.1089/caff.2021.29019.slw] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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