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Fatigue is a condition that may affect physical performance during training sessions. Consequently, this will impact training performance and will also affect the performance of the individual in the long term. Caffeine is extensively used to counteract fatigue; however, it contains several side effects. Theacrine might be used as an alternative to caffeine, providing the same benefits without the side effects. The current study aimed to investigate the effects of 8 weeks of supplementation with theacrine on physical performance and training status of young amateur athletes. Twenty-two subjects were divided into two groups – Theacrine Group (T) and Placebo Group (P) – and evaluated before and after the intervention period. Evaluations included physical tests and hormonal values of insulin like growth factor (IGF)-I and IGF binding protein (IGFBP)-3, used as markers of training status. Results demonstrated that theacrine was not capable of promoting benefits regarding the physical performance of the subjects. It also had no effects on serum secretion of IGF-I and its binding protein, IGFBP-3. Therefore, the findings of this study do not support the use of theacrine to increase physical performance.
Comparative Exercise Physiology, 2022; ## (##): 1-7 Wageningen Academic
ISSN 1755-2540 print, ISSN 1755-2559 online, DOI 10.3920/CEP210034 1
1. Introduction
Fatigue is a condition that may affect the performance in
training sessions and, consequently, impact the efficiency
chronically and also the training status of the individual
(Martin et al., 2018; Theofilidis et al., 2018). Among the
stimulating dietary supplements, in which the function
is to decrease fatigue, the most known and used is the
caffeine (Evans et al., 2020; Guest et al., 2021). However,
it is common for caffeine to cause side effects in some
individuals, such as insomnia, agitation, tremors, and
increased heart rate (Evans et al., 2020).
Theacrine, an alkaloid found mainly in Camellia kucha
Hung T. Chang, is currently gaining attention in the
supplement market (Sheng et al., 2020). The structure of
the theacrine is similar to caffeine; it is even speculated that
it is synthesised in plants from caffeine, although this is
not completely understood yet. Also, the exact mechanism
of action of theacrine has not been fully elucidated.
However, recent research indicates that it probably acts
as an antagonist of adenosine receptors, just like caffeine
(Grgic et al., 2020; Guest et al., 2021; Sheng et al., 2020).
Despite the structural similarity, the literature points out
that theacrine does not present the side effects inherent to
caffeine (Temple et al., 2017). Despite being commercialised
under the allegation of promoting positive effects in physical
performance, the literature is scarce on the subject. We
found only two studies that evaluated the effects of theacrine
in physical performance, and both examined effects only
in an acute way (Bello et al., 2019; Cesareo et al., 2019).
Previous studies have not detected acute effects of theacrine.
However, we hypothesised that perhaps this could have
occurred because the effects are not so noticeably acute,
although chronically we would be able to see these effects.
It is well documented that caffeine produces improvements
in physical performance in training sessions and increases
training load (Guest et al., 2021; Polito et al., 2016).
Cumulatively this could provide a long-term improvement
in performance (Laursen, 2010; Natera et al., 2020; Peterson
Theacrine does not enhance physical performance or training status over 8 weeks
H. Santa Capita Cerqueira1*, H. Tourinho Filho2, M. Corrêa Jr1 and C.E. Martinelli Jr1
1Ribeirao Preto Medical School, University of Sao Paulo, Avenida Bandeirantes, 3900, Ribeirao Preto, SP 14015-130, Brazil; 2School of
Physical Education and Sport of Ribeirao Preto, University of Sao Paulo, Avenida Bandeirantes, 3900, Ribeirao Preto, SP 14015-130, Brazil;
Received: 16 August 2021 / Accepted: 29 November 2021
© 2022 Wageningen Academic Publishers
Fatigue is a condition that may affect physical performance during training sessions. Consequently, this will impact
training performance and will also affect the performance of the individual in the long term. Caffeine is extensively
used to counteract fatigue; however, it contains several side effects. Theacrine might be used as an alternative to
caffeine, providing the same benefits without the side effects. The current study aimed to investigate the effects of
8 weeks of supplementation with theacrine on physical performance and training status of young amateur athletes.
Twenty-two subjects were divided into two groups – Theacrine Group (T) and Placebo Group (P) – and evaluated
before and after the intervention period. Evaluations included physical tests and hormonal values of insulin like
growth factor (IGF)-I and IGF binding protein (IGFBP)-3, used as markers of training status. Results demonstrated
that theacrine was not capable of promoting benefits regarding the physical performance of the subjects. It also
had no effects on serum secretion of IGF-I and its binding protein, IGFBP-3. Therefore, the findings of this study
do not support the use of theacrine to increase physical performance.
Keywords: physical education, physical training, dietary supplements, alkaloids
Comparative Exercise Physiology, 2022 online ARTICLE IN PRESS
H. Santa Capita Cerqueira et al.
2 Comparative Exercise Physiology ## (##)
et al., 2004). However, there is concern about high long-
term caffeine consumption and its possible deleterious
effects (Spaeth et al., 2014).
Therefore, the main objective of this work was to evaluate
the chronic effects of supplementation with theacrine on
physical performance. We also evaluated the secretion of
serum of insulin-like growth factor 1 (IGF-I) and insulin-like
growth factor binding protein-3 (IGFBP-3). This evaluation
has been carried out in order to monitor the training status
of the athletes before and after the intervention. These
markers have been shown to be useful as training status
markers (Nindl and Pierce, 2010) enabling us greater control
over the training status of the subjects.
2. Materials and methods
This is an 8-week longitudinal double-blind clinical trial
type study. The study was registered in The Brazilian
Clinical Trials Registry (number: RBR-63rn74y) and
approved by the Research Ethics Committee of Hospital
das Clínicas – Ribeirão Preto Medical School – HCFMRP
(Universidade de São Paulo – USP); technical opinion no.
Twenty-two flag football male players participated in
this study with ages between 19-24. The sample size was
determined by convenience, according to the acceptance
and availability of the athletes. As inclusion criteria were
adopted: being between 18-25 years old and experience
in the sport of, at least, one year. This was confirmed
by checking the athletes’ files, provided by the team.
As exclusion criteria: the subjects have been taking any
supplementation; took or have been taking any anabolic
steroids. All participants received and signed an informed
consent form in which they were informed of the structure
of the study, and its possible risks and implications.
Study design
The participants were randomised using computer software
and divided into two groups, being instructed to ingest a
capsule 60 min before training sessions only. The content
of the capsule provided to each group was unknown for
both researcher and athletes. One group received capsules
containing 200 mg of theacrine (named T) and the other
group received placebo capsules. The capsules of the
two groups were of the same weight and size. A member
of the team staff was responsible for the receiving and
distribution of the capsules to the subjects. He only had
contact with the players at the time of delivery of the
capsules. Furthermore, he did not know the content in order
to preserve the reliability of the research. Participants were
evaluated in two distinct moments: the first evaluation was
done before the supplementation period (pre); the second
evaluation occurred after 8 weeks of supplementation and
the training program (post). Both the evaluations and the
training sessions had their schedules standardised. The
evaluations included physical tests and blood analyses.
Physical tests
The tests used to evaluate the physical performance of
the athletes were the following, performed as previously
described in the literature: sextuple jump (De Souza
et al., 2006), agility T test (Lockie, 2019), 30 m sprint
(Alemdaroğlu, 2012), 40 s run test (Matsudo test) (Matsudo,
1979; Soares and Anjos, 2003) and 12 min run test (Cooper,
1968). Such tests were chosen because they are related to
the possible effects of theacrine. The literature points out
that the mechanism of action of theacrine is like that of
caffeine, well-known for promoting benefits in different
types of exercise (Guest et al., 2021; Sheng et al., 2020).
Such tests contemplate all of these physical capacities. In
addition, these tests are already known by athletes, which
avoids a possible familiarisation bias.
Anthropometric measurements
Height, body mass, fat mass, and lean mass were
determined. For this, a stadiometer (AVA-312, Avanutri,
Três Rios, Brazil) and a bioimpedance scale (BF 1000,
Beurer, Ulm, Germany) were used. All anthropometric
evaluations were performed one day before physical tests
and in a fasted state.
Blood collection
Blood analyses were performed to determine serum levels of
IGF-1 and its binding protein IGFBP-3. Blood samples were
collected immediately after lunch, respecting the interval
of, at least, 2 h after the last meal, by a professional qualified
nurse. Venous blood sample was collected by puncture
of blood vessel on the anterior forearm. 5 ml blood from
each individual was collected in tubes without addition of
anticoagulant. The samples were immediately stored at
0-4°C, then centrifuged between 0 and 4°C at 1,200 rpm for
12 min and the blood serum stored at -80°C for hormonal
dosages. There was not storage of biological material in a
bank, and the samples were discarded right after the analysis.
Serum levels of IGF-1, IGFBP-3 were determined by specific
immunoassays using a commercial kit and expressed in
ng/ml (Immulite 2000, Siemens, Los Angeles, CA, USA).
All samples of the study were dosed in duplicate within
the same assay. The intra-assay coefficients of variation
were 2.77% for IGF-I; and 2.60% for IGFBP-3. The assays
were carried out in the Endocrinology Laboratory of
Please cite this article as 'in press' Comparative Exercise Physiology
Theacrine and physical performance
Comparative Exercise Physiology ## (##) 3
Hospital of Clínicas in the Medical School of Ribeirão
Preto (Universidade de São Paulo).
Training program
The training of the athletes during the research period
was composed of physical preparation (2 weekly sessions
constituted by resistance training (60 min) and followed by
aerobic training (30 min), totalising about 90 min each) on
Mondays and Thursdays; also, technical-tactical preparation
(on Saturday afternoon and Sunday mornings, in which the
athletes perform physical, technical, and tactical training
specific to the modality). Physical preparation comprised
a full body routine as follows: crunches (5 sets), back squat
(5 sets), bench press (5 sets), seated row (5 sets), barbell
shoulder press (5 sets), standing calf raise machine (5 sets),
biceps curl (3 sets) and triceps pulley extension (3 sets).
The exercises were performed to muscular failure. Loads
were adjusted to allow subjects to perform between 8-12
Diet and total energy expenditure
The total energy expenditure (TEE), as well as the
composition of the diet of the athletes were calculated by
a nutritionist of the team. To estimate TEE, the dietary
reference intakes 2005 (IOM, 2005) were used. Both groups
adopted an isocaloric diet during the intervention, which
was monitored in weekly meetings with the nutritionist.
The energy intake and the distribution of micro and
macronutrients followed the literature recommendations
(Kerksick et al., 2018; Thomas et al., 2016).
Statistical treatment
A linear model of mixed effects was used, adopting a
significance level of 0.05. After a well detailed description
of the data, linear models of mixed effect were adjusted
to compare the group means and moments of interest.
Multiple comparisons were performed by estimating
orthogonal contrasts, obtaining the difference between
means and their respective confidence interval of 95%. The
data were analysed using the SAS software (version 9.3;
SAS Institute, Inc. Cary, NC, USA). The PROC MIXED
of the SAS 9.4 software was used.
3. Results
Table 1 shows the basic characteristics of the participants.
Table 2 shows the changes in body composition before
and after 8-weeks intervention. Both groups had increases
in both lean and fat mass, besides the total body mass
(P<0.01). However, there were no significant differences
between the two groups after the training period for body
mass (P=0.62), lean mass (P=0.69) and fat mass (P=0.52).
Table 3 shows the performance of the subjects before and
after the period of intervention. Based on the data analysis,
both groups improved their performance in all tests, with
significant intra-group difference when comparing pre-
and post-moments. However, there were no significant
difference between the groups for any test performed.
Table 4 shows the serum levels of IGF-I and IGFBP-3 of
the subjects before and after the 8-weeks intervention.
There was a decrease of serum levels of IGF-I and IGFBP-3
in both groups (intra-group) when comparing the pre-
and post-moments. IGF-I (P≤0.01). However, the results
showed no difference when compared between the groups
(inter-groups). There was no difference between groups
regarding TEE.
Table 1. Basic characteristics of the participants.1
Variable Mean ± SD (n=22)
Age (years) 20.05±1.81
Height (cm) 178.27±7.10
Body mass (kg) 78.57±14.70
Lean mass (kg) 63.43±9.96
Fat mass (%) 18.74±3.88
Energy expenditure (kcal) 3,233.82±352.42
1 SD = standard deviation.
Table 2. Anthropometric measurements of the subjects before and after 8-weeks supplementation.1
Variable Theacrine (n=11) Placebo (n=11)
Pre (Mean ± SD) Post (Mean ± SD) ΔPre (Mean ± SD) Post (Mean ± SD) Δ
Body mass (kg) 76.00±14.25 77.82±14.67* 1.82 79.18±16.37 81.17±16.85* 1.99
Lean mass (kg) 61.98±9.89 63.34±10.15* 1.36 63.58±10.88 65.14±11.15* 1.56
Fat mass (kg) 14.02±4.97 14.49±5.12* 0.47 15.60±5.83 16.04± 6.07* 0.44
1 SD = standard deviation. Significant differences pre × post are indicated by an asterisk (P<0.01).
Comparative Exercise Physiology Please cite this article as 'in press'
H. Santa Capita Cerqueira et al.
4 Comparative Exercise Physiology ## (##)
4. Discussion
The main finding of this study was that the chronic use
of theacrine was not capable of promoting improvements
in physical tests of young athletes and could not prevent
the reduction of serum levels of IGF-I and IGFBP-3 after
an 8-week supplementation. To our knowledge, this was
the first study to evaluate the effects of the theacrine
chronically. The rationale of the use of theacrine would
be to have the benefits of caffeine, but without the
undesired side effects, which was not demonstrated in our
results. It is worth mentioning that only two studies were
found in the literature that evaluated the acute effects of
supplementation, on physical performance, and they did not
demonstrate the efficiency of theacrine supplementation for
this purpose either (Bello et al., 2019; Cesareo et al., 2019).
One of these studies evaluated football (soccer) players of
both genders in 4 conditions: placebo, theacrine, caffeine,
and theacrine + caffeine. The subjects were submitted to a
treadmill running protocol, simulating a football match. The
subjects ran 45 min and, after a 15 min break, ran another
45 min. They performed a running test until exhaustion at
85% of V
̇O2max, in addition to cognitive tests at the end of
the protocol. In addition, the subjects performed cognitive
tests within the protocol break. There was no significant
difference in both parameters evaluated. (Bello et al., 2019).
Another study evaluated the effects of theacrine on
maximum strength and strength endurance in trained
subjects (Cesareo et al., 2019). In this cross-over designed
study, 20 resistance-trained men were evaluated under four
different conditions: caffeine 300 mg, theacrine 300 mg,
caffeine 150 mg + theacrine 150 mg, and placebo. The study
protocol was performed 90 min after capsule ingestion
and involved one-repetition maximum (1RM) in bench
press and squat; repetitions to failure in both exercises (at
70% of 1RM); and 2 km rowing time trial. The study also
evaluated focus, energy, and motivation to exercise. The
results showed that theacrine did not promote benefits in
any of the variables evaluated.
It is well established that caffeine is efficient in increasing
the performance in strength, endurance, speed and
performance in sports in general (Guest et al., 2021). In
addition, caffeine provides increases in the training session
load (Guest et al., 2021; Polito et al., 2016). This cumulative
effect can increase long-term performance (Laursen, 2010).
Furthermore, habitual consumption of caffeine is related
to greater motor performance (Hameleers et al., 2000).
However, data available in the literature added to those
presented in this study indicate that it does not seem to
occur with theacrine as in an acute form (Bello et al., 2019;
Cesareo et al., 2019), as well as in a chronic form, analysed
in this current study.
Table 4. Hormonal concentrations before and after the intervention.1
Variable2Theacrine (n=11) Placebo (n=11)
Pre (Mean ± SD) Post (Mean ± SD) ΔPre (Mean ± SD) Post (Mean ± SD) Δ
IGF-I (ng/ml) 268.82±52.38 255.59±49.54* -13.23 260.91±63.07 248.67±59.83* -12.24
IGFBP-3 (ug/ml) 4.19±0.40 4.01±0.39* -0.18 4.07±0.41 3.90±0.39* -0.17
1 SD = standard deviation. Significant differences pre × post are indicated by an asterisk (P<0.01).
2 IGF = insulin growth factor; IGFBP = insulin growth factor binding protein.
Table 3. Performance of physical tests before and after the intervention.1
Variable Theacrine (n=11) Placebo (n=11)
Pre (Mean ± SD) Post (Mean ± SD) ΔPre (Mean ± SD) Post (Mean ± SD) Δ
Sextuple jump (m) 12.96±0.89 13.52±1.09* 0.56 12.18±1.31 13.00±1.48* 0.82
T test (s) 9.96±0.86 9.68±0.81* -0.28 9.94±0.73 9.65±0.78* -0.29
30 m sprint (s) 4.69±0.44 4.55±0.40* -0.14 4.69±0.36 4.54±0.35* -0.15
40 s run test (m) 212.73±34.95 222.91±36.63* 10.18 225.45±22.07 236.27±23.92* 10.82
Cooper test (m) 1,745.45±391.21 1,831.50±404.10* 86.09 1,734.55±221.47 1,822.82±239.48* 87.90
1 SD = standard deviation. Significant differences pre × post are indicated by an asterisk (P<0.01).
Please cite this article as 'in press' Comparative Exercise Physiology
Theacrine and physical performance
Comparative Exercise Physiology ## (##) 5
Besides the strength and endurance evaluated in the
previous studies (Bello et al., 2019; Cesareo et al., 2019),
our study also evaluated the anaerobic power, agility and
sprint ability. In these parameters, supplementation with
theacrine did not show to be effective either. It is important
to highlight that only field tests were used, which better
reflect the specificity of the tasks performed by the subjects
in their daily training.
On the other hand, supplementation with theacrine is
safe and does not cause side effects commonly caused by
caffeine, moreover some studies showed improvement
in focus and willingness to exercise with its use (Clewell
et al., 2016; Sheng et al., 2020; Ziegenfuss et al., 2017),
however with regard to physical performance, our data
do not provide evidence that support the use of theacrine.
It is important to point that none of the subjects related
any type of side effect due to the use of theacrine over the
8-week supplementation.
In the current study, theacrine also provided no long-term
benefits in relation to training status of the subjects, as
evaluated by serum levels of IGF-I and IGFBP-3. These
markers were used, as the literature points to an association
between IGF-IGFBPs system and the training status,
mostly IGF-I and IGFBP-3 (Fornel et al., 2020; Nindl and
Pierce, 2010; Tourinho Filho et al., 2017). It may serve as
an important tool to control the volume and intensity of
training during the season.
According to the literature, when the individual is in a
phase of more intense training and/or inadequate nutrition,
serum levels of IGF-I and IGFBP-3 tend to decrease and
if this condition is not monitored and the suppression
persists, then the athlete may reach an overtraining
condition (Eliakim and Nemet, 2020; Tourinho Filho et
al., 2017). In this study, the use of theacrine did not alter
the kinetic of the system IGF-I-IGFBPs when compared
between the groups, nor did it prevent the reduction of
serum levels in the second moment of evaluation in both
groups. Studies have shown an association between fatigue
levels and IGF-1, both in athletes and patients with chronic
non-communicable diseases (Hecksteden et al., 2016;
Van Langenberg et al., 2014). Our results did not show
any difference in either performance or hormone levels
between the groups T and P. Thus, in the present study,
theacrine did not show positive effects in the improvement
of performance of the subjects or in their training status.
The limitations of the study include the sample size.
However, the number of subjects who participated is in line
with the literature, being higher than most investigations
with theacrine (Sheng et al., 2020). In addition, the study
employed very strict inclusion and exclusion criteria,
in addition to controlling the subjects’ training and
feeding program. Another limitation is the absence of
questionnaires or visual analog scales. We believe future
studies could include them. If used in conjunction with
physical performance tests could provide even greater
control over subject performance and mental/training
status. It is also known that the hydration status can
influence the bioimpedance results. Although all the
manufacturer’s protocols were followed, we did not assess
the athletes’ hydration status, with measurements, such as
urine specific gravity.
5. Conclusions
The findings of the present study show that the chronic use
of theacrine was not capable of causing an improvement
in the physical performance of the athletes. It also did not
prevent the reduction of serum secretion of IGF-I and
IGFBP-3 nor in the body composition after 8 weeks of
supplementation of a training program, Thus, our findings
do not support the use of theacrine in order to improve
physical performance, neither by athletes nor by exercise
practitioners in general.
The authors are grateful to Coordination for the
Improvement of Higher Education Personnel (CAPES –
Proc. no. 88882.378517/2019-01) and National Council
for Scientific and Technological Development (CNPq)
(CNPq – Proc. no. 142327/2018-2), Brazil, for scholarships.
Conflict of interest
The authors declare that they have no conflict of interest.
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Please cite this article as 'in press' Comparative Exercise Physiology
Theacrine and physical performance
Comparative Exercise Physiology ## (##) 7
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The search to increase physical performance is inherent to physical activity practitioners, and nutrition features are among the alternatives to seeking such an increase. The literature from the area has shown that different substances can promote beneficial effects over physical performance. One substance that has come into the spotlight is theacrine, an alkaloid similar to caffeine, which aims to increase physical performance. However, the studies on this supplement are scarce. Therefore, this study is a randomized, controlled trial that aimed to verify the effects of theacrine supplementation over physical performance in young male athletes, by applying a battery of physical tests. Twenty-two male amateur flag-football athletes were recruited. Subjects were divided into two groups and assessed at two moments, which were 72 h apart. The first assessment served as a basal measurement. In the second, the subjects ingested the supplement or a placebo 60 min before the following tests: sextuple jump, agility T test, 30 m sprint, 40 s run test (Matsudo test), and 12 min run test (Cooper test). There was no difference between the groups in any of the tests. Therefore, the findings of this study do not support the use of theacrine to increase physical performance.
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Theacrine, i.e., 1,3,7,9-tetramethyluric acid, is one of the major purine alkaloids found in leaf of a wild tea plant species Camellia kucha Hung T. Chang. Theacrine has been attracted great attentions academically owing to its diverse health benefits. Present review examines the advances in the research on the health beneficial effects of theacrine, including antioxidant effect, anti-inflammatory effect, locomotor activation and reducing fatigue effects, improving cognitive effect, hypnotic effect, ameliorating lipid metabolism and inhibiting breast cancer cell metastasis effect. The inconsistent results in this research field and further expectations were also discussed.
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Following critical evaluation of the available literature to date, The International Society of Sports Nutrition (ISSN) position regarding caffeine intake is as follows: 1. Supplementation with caffeine has been shown to acutely enhance various aspects of exercise performance in many but not all studies. Small to moderate benefits of caffeine use include, but are not limited to: muscular endurance, movement velocity and muscular strength, sprinting, jumping, and throwing performance, as well as a wide range of aerobic and anaerobic sport-specific actions. 2. Aerobic endurance appears to be the form of exercise with the most consistent moderate-to-large benefits from caffeine use, although the magnitude of its effects differs between individuals. 3. Caffeine has consistently been shown to improve exercise performance when consumed in doses of 3–6 mg/kg body mass. Minimal effective doses of caffeine currently remain unclear but they may be as low as 2 mg/kg body mass. Very high doses of caffeine (e.g. 9 mg/kg) are associated with a high incidence of side-effects and do not seem to be required to elicit an ergogenic effect. 4. The most commonly used timing of caffeine supplementation is 60 min pre-exercise. Optimal timing of caffeine ingestion likely depends on the source of caffeine. For example, as compared to caffeine capsules, caffeine chewing gums may require a shorter waiting time from consumption to the start of the exercise session. 5. Caffeine appears to improve physical performance in both trained and untrained individuals. 6. Inter-individual differences in sport and exercise performance as well as adverse effects on sleep or feelings of anxiety following caffeine ingestion may be attributed to genetic variation associated with caffeine metabolism, and physical and psychological response. Other factors such as habitual caffeine intake also may play a role in between-individual response variation. 7. Caffeine has been shown to be ergogenic for cognitive function, including attention and vigilance, in most individuals. 8. Caffeine may improve cognitive and physical performance in some individuals under conditions of sleep deprivation. 9. The use of caffeine in conjunction with endurance exercise in the heat and at altitude is well supported when dosages range from 3 to 6 mg/kg and 4–6 mg/kg, respectively. 10. Alternative sources of caffeine such as caffeinated chewing gum, mouth rinses, energy gels and chews have been shown to improve performance, primarily in aerobic exercise. 11. Energy drinks and pre-workout supplements containing caffeine have been demonstrated to enhance both anaerobic and aerobic performance.
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Background High volume power training (HVPT) involves high volumes of high-velocity resistance training, with the aim to improve repeated high-intensity efforts (RHIEs). Repeat power ability (RPA) is the ability to repeatedly produce maximal or near maximal efforts. Assessments of RPA using external loading may determine the ability to perform repeat RHIEs typical of many sports and, therefore, provide useful information on the effectiveness of training.Objectives(1) Identify the different HVPT protocols; (2) examine the acute responses and chronic adaptations to different HVPT protocols; (3) identify different lower body RPA assessment protocols and highlight similarities, differences and potential limitations between each protocol, and; (4) describe the reliability and validity of RPA assessments.Methods An electronic search was performed using SPORTDiscus, PubMed, CINAHL and Embase for studies utilising HVPT protocols and assessments of RPA. Eligible studies included peer-reviewed journal articles published in English.ResultsTwenty studies met the inclusion criteria of the final review. Of the eight longitudinal studies, three were rated as fair and five were rated as poor methodological quality, respectively. In contrast, all 12 cross-sectional studies were considered to have a low risk of bias. Preliminary evidence suggests that HVPT can enhance RHIE, RPA, anaerobic capacity, anaerobic power and aerobic performance. HVPT generally consists of 2–3 sessions per week, utilising loads of 30–40% 1 repetition maximum (RM), for 3–5 sets of 10–20 repetitions, with inter-set rest periods of 2–3 min. RPA assessments can be valid and reliable and may provide useful information on an athlete’s ability to perform RHIE and the success of HVPT programmes.ConclusionsHVPT can be used to improve a number of physical qualities including RPA and RHIE; while a variety of RPA assessments provide valid and reliable information regarding the athlete’s ability to perform RHIEs. Considering the heterogeneity in the HVPT protocols currently used and the relatively low volume and quality of longitudinal publications in this area, further studies are needed to identify the effects of a variety of HVPT methods on RPA, RHIE and other performance outcomes and to identify the most valid and reliable RPA outcomes to use in such studies.
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Background: TeaCrine® is the synthetic version to naturally occurring theacrine (1, 3, 7, 9-tetramethyluric acid) found in the leaves of Camellia kucha tea plants. A few studies have examined the effects of TeaCrine® on cognitive perception, but no research exists examining its effects on resistance exercise performance. The purpose of this study was to determine the efficacy of TeaCrine®, a caffeine-like compound, on maximal muscular strength, endurance, and power performance in resistance-trained men. Methods: Twelve resistance-trained men participated in a randomized, double-blind, cross-over designed study. Each participant performed one-repetition maximum (1RM) bench press, 1RM squat, bench press repetitions to failure (RTF) at 70% 1RM, squat RTF at 70% 1RM, and 2-km rowing time trial 90 min after consumption of: (1) Caffeine 300 mg (CAFF300); (2) TeaCrine® 300 mg (TEA300); (3) TeaCrine® + Caffeine (COMBO; 150 mg/150 mg); (4) Placebo 300 mg (PLA). Power and velocity were measured using a TENDO Power Analyzer. Visual analogue scales for energy, focus, motivation to exercise, and fatigue were administered at baseline and 90 min post-treatment ingestion (pre-workout). Rating of perceived exertion was assessed after bench press RTF and squat RTF. Results: There were no differences between groups for 1RM, RTF, and power in the bench press and squat exercises. Only CAFF300 resulted in significant increases in perceived energy and motivation to exercise vs. TEA300 and PLA (Energy: + 9.8%, 95% confidence interval [3.3-16.4%], p < 0.01; + 15.3%, 95% CI [2.2-28.5%], p < 0.02; Motivation to exercise: + 8.9%, 95% CI [0.2-17.6%], p = 0.04, + 14.8%, 95% CI [4.7-24.8%], p < 0.01, respectively) and increased focus (+ 9.6%, 95% CI [2.1-17.1%], p = 0.01) vs. TEA300, but there were no significant differences between CAFF300 and COMBO (Energy + 3.9% [- 6.9-14.7%], Focus + 2.5% [- 6.3-11.3%], Motivation to exercise + 0.5% [- 11.6-12.6%]; p > 0.05). Conclusion: Neither TEA300, CAFF300, COMBO, or PLA (when consumed 90 min pre-exercise) improved muscular strength, power, or endurance performance in resistance-trained men. Only CAFF300 improved measures of focus, energy, and motivation to exercise.
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Background Theacrine (1,3,7,9-tetramethyluric-acid) is a pure alkaloid with a similar structure to caffeine and acts comparably as an adenosine receptor antagonist. Early studies have shown non-habituating effects, including increases in energy and focus in response to Teacrine®, the compound containing pure theacrine. The purpose of this study was to determine and compare the effects of Teacrine® and caffeine on cognitive performance and time-to-exhaustion during a simulated soccer game in high-level male and female athletes. Methods Male and female soccer players (N = 24; MAge = 20.96 ± 2.05y, MMaleVO2max = 55.31 ± 3.39 mL/O2/kg, MFemaleVO2max = 50.97 ± 3.90 mL/O2/kg) completed a 90-min simulated treadmill soccer match over four randomized sessions (TeaCrine®, caffeine, TeaCrine® + caffeine, placebo). Cognitive testing at halftime and end-of-game including simple reaction time (SRT), choice RT (CRT), and cognitive-load RT with distraction questions (COGRT/COGRTWrong) was performed, with a run time-to-exhaustion (TTE) at 85% VO2max following end-of-game cognitive testing. Session times and pre-exercise nutrition were controlled. RM-MANOVAs with univariate follow-ups were conducted and significance was set at P < 0.05. Results TTE trended towards significance in TeaCrine® and TeaCrine® + caffeine conditions compared to placebo (P < 0.052). A condition main effect (P < 0.05) occurred with faster CRT in caffeine and TeaCrine® + caffeine compared to placebo. COGRTWrong showed a significant time main effect, with better accuracy at end-of-game compared to halftime (P < 0.05). A time x condition interaction in SRT (P < 0.05) showed placebo improved from halftime to end-of-game. Conclusions The 27–38% improvements in TTE reflect increased performance capacity that may have important implications for overtime scenarios. These findings suggest TeaCrine® favorably impacts endurance and the combination with caffeine provides greater benefits on cognitive function than either supplement independently.
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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 AMSTAR 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 GRADE 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.
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Regular exercise with the appropriate intensity and duration may improve an athlete’s physical capacities by targeting different performance determinants across the endurance–strength spectrum aiming to delay fatigue. The mechanisms of muscle fatigue depend on exercise intensity and duration and may range from substrate depletion to acidosis and product inhibition of adenosinetriphosphatase (ATPase) and glycolysis. Fatigue mechanisms have been studied in isolated muscles; single muscle fibers (intact or skinned) or at the level of filamentous or isolated motor proteins; with each approach contributing to our understanding of the fatigue phenomenon. In vivo methods for monitoring fatigue include the assessment of various functional indices supported by the use of biochemical markers including blood lactate levels and more recently redox markers. Blood lactate measurements; as an accompaniment of functional assessment; are extensively used for estimating the contribution of the anaerobic metabolism to energy expenditure and to help interpret an athlete’s resistance to fatigue during high intensity exercise. Monitoring of redox indices is gaining popularity in the applied sports performance setting; as oxidative stress is not only a fatigue agent which may play a role in the pathophysiology of overtraining syndrome; but also constitutes an important signaling pathway for training adaptations; thus reflecting training status. Careful planning of sampling and interpretation of blood biomarkers should be applied; especially given that their levels can fluctuate according to an athlete’s lifestyle and training histories.
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Background: Sports nutrition is a constantly evolving field with hundreds of research papers published annually. In the year 2017 alone, 2082 articles were published under the key words 'sport nutrition'. Consequently, staying current with the relevant literature is often difficult. Methods: This paper is an ongoing update of the sports nutrition review article originally published as the lead paper to launch the Journal of the International Society of Sports Nutrition in 2004 and updated in 2010. It presents a well-referenced overview of the current state of the science related to optimization of training and performance enhancement through exercise training and nutrition. Notably, due to the accelerated pace and size at which the literature base in this research area grows, the topics discussed will focus on muscle hypertrophy and performance enhancement. As such, this paper provides an overview of: 1.) How ergogenic aids and dietary supplements are defined in terms of governmental regulation and oversight; 2.) How dietary supplements are legally regulated in the United States; 3.) How to evaluate the scientific merit of nutritional supplements; 4.) General nutritional strategies to optimize performance and enhance recovery; and, 5.) An overview of our current understanding of nutritional approaches to augment skeletal muscle hypertrophy and the potential ergogenic value of various dietary and supplemental approaches. Conclusions: This updated review is to provide ISSN members and individuals interested in sports nutrition with information that can be implemented in educational, research or practical settings and serve as a foundational basis for determining the efficacy and safety of many common sport nutrition products and their ingredients.
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Mental fatigue reflects a change in psychobiological state, caused by prolonged periods of demanding cognitive activity. It has been well documented that mental fatigue impairs cognitive performance; however, more recently, it has been demonstrated that endurance performance is also impaired by mental fatigue. The mechanism behind the detrimental effect of mental fatigue on endurance performance is poorly understood. Variables traditionally believed to limit endurance performance, such as heart rate, lactate accumulation and neuromuscular function, are unaffected by mental fatigue. Rather, it has been suggested that the negative impact of mental fatigue on endurance performance is primarily mediated by the greater perception of effort experienced by mentally fatigued participants. Pageaux et al. (Eur J Appl Physiol 114(5):1095–1105, 2014) first proposed that prolonged performance of a demanding cognitive task increases cerebral adenosine accumulation and that this accumulation may lead to the higher perception of effort experienced during subsequent endurance performance. This theoretical review looks at evidence to support and extend this hypothesis.