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Ambrozy CA, Hawes NE, Hayden OL, Sortz I, Malek MH. Caffeine Expectancy Does Not Influence the Physical Working Capacity at the Fatigue Threshold. J Strength Cond Res 2024; 38:1056-1062. [PMID: 38781467 DOI: 10.1519/jsc.0000000000004742] [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: 05/25/2024]
Abstract
ABSTRACT Ambrozy, CA, Hawes, NE, Hayden, OL, Sortzi, I, and Malek, MH. Caffeine expectancy does not influence the physical working capacity at the fatigue threshold. J Strength Cond Res 38(6): 1056-1062, 2024-The placebo effect occurs when a desired outcome is experienced due to the belief that a treatment is effective, even in the absence of an active ingredient. One explanation for this effect is based on a person's expectations of a drug or supplement. Although caffeine's effects on sports performance have been studied, little is known about how expectations of caffeine affect neuromuscular fatigue during continuous muscle action. The physical working capacity at the fatigue threshold (PWCFT) can be used to assess neuromuscular fatigue noninvasively using surface electromyography. Thus, the purpose of this study was to investigate whether caffeine expectancy influences PWCFT. We hypothesized that regardless of expectancy, caffeine consumption would delay neuromuscular fatigue. The study involved 8 healthy college-aged men (mean ± SEM: age, 25.6 ± 1.0 years) who visited the laboratory on 4 occasions, each separated by 7 days. The subjects completed 4 experimental conditions, in random order, where they were told that they were consuming caffeine or placebo and either received caffeine or placebo. After consuming the drink, the subjects remained in the laboratory for an hour and then performed an incremental exercise test. The results showed that the condition where subjects were told that they were consuming caffeine and received caffeine had significantly higher mean values for maximal power output (F(3, 21) = 11.75; p < 0.001), PWCFT (F(3, 21) = 12.28; p < 0.001), PWCFT (%maximal power output; F(3, 21) = 8.75; p < 0.001), and heart rate at end exercise (%predicted; F(3, 21) = 3.83; p = 0.025) compared with the 2 conditions where placebo was received. However, no statistically significant mean differences were found from the condition where subjects were told that they were consuming placebo but consuming caffeine. This suggests that a person's expectancy and potential somatic response may serve as a cue for how an ergogenic aid or placebo could affect subsequent performance.
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Affiliation(s)
- Christina A Ambrozy
- Physical Therapy Program, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan; and
- Integrative Physiology of Exercise Laboratory, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan
| | - Nicole E Hawes
- Physical Therapy Program, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan; and
- Integrative Physiology of Exercise Laboratory, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan
| | - Olivia L Hayden
- Physical Therapy Program, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan; and
- Integrative Physiology of Exercise Laboratory, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan
| | - Isabella Sortz
- Physical Therapy Program, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan; and
- Integrative Physiology of Exercise Laboratory, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan
| | - Moh H Malek
- Physical Therapy Program, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan; and
- Integrative Physiology of Exercise Laboratory, Department of Health Care Sciences, College of Pharmacy and Health Sciences, Wayne State University, Detroit, Michigan
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Taheri Karami G, Hemmatinafar M, Koushkie Jahromi M, Nemati J, Niknam A. Repeated mouth rinsing of coffee improves the specific-endurance performance and jump performance of young male futsal players. J Int Soc Sports Nutr 2023; 20:2214108. [PMID: 37190757 DOI: 10.1080/15502783.2023.2214108] [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: 05/17/2023] Open
Abstract
BACKGROUND Mouth-rinsing with ergogenic solutions such as carbohydrate and caffeinated drinks has been considered among athletes as a practical nutritional strategy. Therefore, this study aimed to determine the effect of repeated coffee mouth-rinsing (CMR) doses on specific performances of futsal players. METHOD Twenty-four male futsal players randomly participated in this randomized, double-blind, and crossover design study. During the intervention, participants were randomly placed in four different conditions including 1. low-dose CMR (LDC, n = 6, ~60 mg caffeine); 2. high-dose CMR (HDC, n = 6, ~125 mg caffeine); 3. decaffeinated CMR (PLA, n = 6, ~10 mg caffeine); and 4. no CMR (CON, n = 6). Vertical jump height was measured at baseline, baseline after CMR (baseline-CMR), immediately after the intermittent futsal endurance test (FIET) (IA-FIET), 5 min after the FIET (5"A-FIET) and 10 min after the FIET (10"A-FIET). Perceived fatigue was also measured by visual analogue scale (VAS) at baseline, IA-FIET, 5"A-FIET, and 10"A-FIET. CMR was also performed at baseline, during FIET (Repeated between levels), and 10'A-FIET. The collected data were analyzed (with SPSS software) by one- and two-way repeated measure ANOVA and Bonferroni post hoc test at P < 0.05 level. RESULTS The findings of the present study illustrated that the perceived fatigue in IA-FIET increased significantly compared to the baseline which was accompanied by a significant decrease in 5"A-FIET and 10"A-FIET compared to IA-FIET (P < 0.05), and no significant difference was observed between conditions in the baseline, IA-FIET, 5"A-FIET, and 10"A-FIET (P > 0.05). However, HDC and LDC rose significantly the distance covered in FIET compared to CON and PLA (P < 0.05). In addition, HDC increased the FIET performance more than LDC (P < 0.05). Although there was no difference between any of the conditions at baseline (P > 0.05), baseline-CMR increased significantly the vertical jump height (P < 0.05). At IA-FIET, vertical jump height decreased to baseline levels in CMR conditions but increased in 5"A-FIET, which remained constant until 10"A-FIET (P < 0.05). In addition, vertical jump height in HDC and LDC conditions was significantly higher than CON in IA-FIET, 5"A-FIET, and 10"A-FIET. CONCLUSION This study showed that repeated CMR with low and high doses is a useful strategy to improve specific futsal performance. However, higher dose CMR appears to have more profound effects on performance improvement than lower doses.
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Affiliation(s)
- Ghasem Taheri Karami
- Department of Sport Science, Faculty of Education and Psychology, Shiraz University, Shiraz, Iran
| | - Mohammad Hemmatinafar
- Department of Sport Science, Faculty of Education and Psychology, Shiraz University, Shiraz, Iran
| | - Maryam Koushkie Jahromi
- Department of Sport Science, Faculty of Education and Psychology, Shiraz University, Shiraz, Iran
| | | | - Alireza Niknam
- Department of Sport Science, Faculty of Education and Psychology, Shiraz University, Shiraz, Iran
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Filip-Stachnik A, Krzysztofik M, Del Coso J, Wilk M. Acute effects of two caffeine doses on bar velocity during the bench press exercise among women habituated to caffeine: a randomized, crossover, double-blind study involving control and placebo conditions. Eur J Nutr 2021; 61:947-955. [PMID: 34664106 PMCID: PMC8854307 DOI: 10.1007/s00394-021-02708-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Accepted: 10/08/2021] [Indexed: 11/24/2022]
Abstract
PURPOSE The main goal of this study was to evaluate the effectiveness of two different doses of caffeine (3 and 6 mg/kg) to enhance bar velocity during the bench press in women habituated to caffeine. METHODS Twelve recreationally trained women (age: 23.3 ± 0.8 years, body mass: 60.7 ± 5.7 kg, bench press one-repetition maximum (1RM): 44.3 ± 7.8 kg, daily caffeine ingestion: 5.7 ± 2.0 mg/kg/day) participated in a randomized double-blind experimental design. Each participant performed four different experimental sessions: after no supplementation (control, CON), after ingesting 3 and 6 mg/kg of caffeine (CAF-3 and CAF-6, respectively), or after ingesting a placebo (PLAC). In each experimental session, the participants performed 3 sets of 3 repetitions of the bench press exercise at 50% 1RM. RESULTS A two-way repeated-measures ANOVA with subsequent post hoc analyses indicated significant increases in peak velocity (p < 0.01; ES = 0.91) and mean velocity (p < 0.01; ES = 0.78) after the intake of CAF-6 compared to CON. The study did not show significant differences in bar velocity between CAF-6 and PLAC and between CAF-3 and PLAC. No significant differences in bar velocity were observed between CAF-3 and CAF-6 conditions. CONCLUSION These results suggest that 6 mg/kg of caffeine can be an effective dose to improve power-specific training outcomes in women habituated to caffeine. However, the ergogenic effect of 6 mg/kg of caffeine may be derived from a combination of biological effects and expectancy, as this dose was only superior to the control condition with no differences over the placebo.
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Affiliation(s)
- Aleksandra Filip-Stachnik
- Institute of Sport Sciences, The Jerzy Kukuczka Academy of Physical Education, ul. Mikolowska 72a, 40-065, Katowice, Poland.
| | - Michal Krzysztofik
- Institute of Sport Sciences, The Jerzy Kukuczka Academy of Physical Education, ul. Mikolowska 72a, 40-065, Katowice, Poland
| | - Juan Del Coso
- Centre for Sport Studies, Rey Juan Carlos University, Fuenlabrada, Spain
| | - Michal Wilk
- Institute of Sport Sciences, The Jerzy Kukuczka Academy of Physical Education, ul. Mikolowska 72a, 40-065, Katowice, Poland
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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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Placebo Effect of Caffeine on Substrate Oxidation during Exercise. Nutrients 2021; 13:nu13030782. [PMID: 33673567 PMCID: PMC7997444 DOI: 10.3390/nu13030782] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 02/22/2021] [Accepted: 02/23/2021] [Indexed: 11/17/2022] Open
Abstract
By using deceptive experiments in which participants are informed that they received caffeine when, in fact, they received an inert substance (i.e., placebo), several investigations have demonstrated that exercise performance can be enhanced to a similar degree as a known caffeine dose. This 'placebo effect' phenomenon may be part of the mechanisms explaining caffeine's ergogenicity in exercise. However, there is no study that has established whether the placebo effect of caffeine is also present for other benefits obtained with acute caffeine intake, such as enhanced fat oxidation during exercise. Therefore, the aim of this investigation was to investigate the placebo effect of caffeine on fat oxidation during exercise. Twelve young men participated in a deceptive double-blind cross-over experiment. Each participant completed three identical trials consisting of a step incremental exercise test from 30 to 80% of V.O2max. In the two first trials, participants ingested either 3 mg/kg of cellulose (placebo) or 3 mg/kg of caffeine (received caffeine) in a randomized order. In the third trial, participants were informed that they had received 3 mg/kg of caffeine, but a placebo was provided (informed caffeine). Fat oxidation rates were derived from stoichiometric equations. In received caffeine, participants increased their rate of fat oxidation over the values obtained with the placebo at 30%, 40%, 50%, and 60% of V.O2max (all p < 0.050). In informed caffeine, participants increased their rate of fat oxidation at 30%, 40%, 50% 60%, and 70% of V.O2max (all p < 0.050) over the placebo, while there were no differences between received versus informed caffeine. In comparison to placebo (0.32 ± 0.15 g/min), the rate of maximal fat oxidation was higher in received caffeine (0.44 ± 0.22 g/min, p = 0.045) and in informed caffeine (0.41 ± 0.20 g/min, p = 0.026) with no differences between received versus informed caffeine. However, the intensity at which maximal fat oxidation rate was obtained (i.e., Fatmax) was similar in placebo, received caffeine, and informed caffeine trials (42.5 ± 4.5, 44.2 ± 9.0, and 41.7 ± 10.5% of V.O2max, respectively, p = 0.539). In conclusion, the expectancy of having received caffeine produced similar effects on fat oxidation rate during exercise than actually receiving caffeine. Therefore, the placebo effect of caffeine is also present for the benefits of acute caffeine intake on substrate oxidation during exercise and it may be used to enhance fat oxidation during exercise in participants while reducing any risks to health that this substance may have.
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