The acute effects of green tea and carbohydrate
co-ingestion on systemic inflammation and
oxidative stress during sprint cycling
Katsuhiko Suzuki 1, Masaki Takahashi 1, Chia-Yang Li 2, Shiuan-Pey Lin
3
, Miki Tomari 1 , Cecilia Shing 4 , Shih-Hua Fang 5
1 Faculty of Sport Sciences, Waseda University, Tokorozawa, Japan.
2 Department of Genome Medicine, College of Medicine, and Center for
Infectious Disease and Cancer Research, Kaohsiung Medical University,
Kaohsiung, Taiwan.
3 School of Pharmacy, China Medical University, Taichung, Taiwan.
4 School of Health Sciences, University of Tasmania, Launceston,
Australia.
5 Institute of Athletics, National Taiwan University of Sport, No. 16, Sec.
1, Shuan-Shih Road, Taichung 40404, Taiwan.
1
Abstract
Green tea has anti-oxidative and anti-inflammatory effects which may be
beneficial to athletes performing high intensity exercise. This study
investigated the effects of carbohydrate and green tea co-ingestion on
sprint cycling performance, and associated oxidative stress and
immunoendocrine responses to exercise. In a crossover design, nine
well-trained male cyclists completed three sets of eight repetitions of 100
m uphill sprint cycling while ingesting green tea and carbohydrate (TEA)
(22 mg/kg body mass catechins, 6 mg/kg body mass caffeine, 230 mg/kg
glucose and 110 mg/kg fructose) or carbohydrate only (230 mg/kg body
mass glucose and 110 mg/kg body mass fructose) (CHO) during each 10
min recovery period between sets. Blood samples were collected before
exercise, 10 min after exercise and 14 h after exercise. There was no
effect of acute TEA ingestion on cycling sprint performance (p=0.285),
although TEA maintained post-exercise testosterone and lymphocyte
concentrations, which decreased significantly in the CHO group
(p<0.001). While there was a trend for lower post-exercise neutrophil
count with TEA (p=0.05), there were no significant differences between
TEA and CHO for circulating cytokines (p>0.20), markers of oxidative
2
stress and antioxidant capacity (p>0.17), adiponectin concentration
(p=0.60) or muscle damage markers (p>0.64). While acute green tea
ingestion prevents the post-exercise decrease in testosterone and
lymphocytes, it does not appear to benefit cycling sprint performance or
reduce markers of oxidation and inflammation when compared to
carbohydrate alone.
3
Introduction
Consideration of the types of fluids cyclists should ingest during a
race requires close consideration. In addition to preventing dehydration,
fluid also provides a chance to deliver fuel during road cycling
(Jeukendrup 2011). Researchers have reported improvements in cycling
performance with the ingestion of popular energy drinks, in which
carbohydrate is the basic component (Higgins et al. 2010). The benefits
of carbohydrate ingestion include the maintenance of plasma glucose
concentration, delay in the onset of fatigue, and enhancement of exercise
performance (Costill and Hargreaves 1992). The serial administration of
carbohydrate in a mouth rinse has also been shown to significantly
improve peak power output during sprint cycling (Phillips et al. 2014).
The other major ingredient in many energy drinks is caffeine. Several
studies have shown that 3–6 mg/kg caffeine supplementation is effective
for enhancing sport performance during both endurance and short-term,
high-intensity exercise in trained athletes (Astorino et al. 2012; Burke
2008; Goldstein et al. 2010; Warren et al. 2010). Previous studies have
also observed positive additional effects when caffeine is added to a
4
carbohydrate solution (Beaven et al. 2013; Cooper et al. 2014; Gant et al.
2010; Hulston and Jeukendrup 2008; Pedersen et al. 2008). Cooper et al.
has demonstrated that coingestion of 25 g of carbohydrate and 100 mg of
caffeine was effective in attenuating fatigue and reducing the rating of
perceived exertion (RPE) during intermittent sprinting (Cooper et al.
2014). Coingestion of carbohydrate and caffeine has also been shown to
enhance cycling performance by 4.6% compared with carbohydrate alone
(Hulston and Jeukendrup 2008) and enhance the psychological status of
players during 90 min of simulated soccer activity (Gant et al. 2010). A
combination of carbohydrate and caffeine mouth rinses might rapidly
enhance power production and benefit short sprint exercise performance
(Beaven et al. 2013). A previous study indicated that in trained subjects
coingestion of carbohydrate and caffeine has an additive effect on rates of
postexercise muscle glycogen accumulation compared with consumption
of carbohydrate alone (Pedersen et al. 2008). Meanwhile, the RPE was
lower in the carbohydrate and caffeine trial than the carbohydrate trial
during a rugby union simulation protocol (Roberts et al. 2010).
There is increasing interest in the potential ergogenic effects of green
tea (Camellia sinensis) on exercise performance (Chacko et al. 2010;
5
Ichinose et al. 2011), as green tea is also rich in caffeine and antioxidant
compounds, such as catechins. Acute green tea extract ingestion
(containing greater than 150 mg caffeine) has been shown to increase fat
metabolism at rest (Dulloo et al. 1999; Rumpler et al. 2001) and during
exercise (Venables et al. 2008) to a greater extent than the same dose of
caffeine alone, to increase total antioxidant capacity at rest in trained
male cyclists (Jowko et al. 2015) and to reduce markers of inflammation
in obesity (Bogdanski et al. 2012). Alterations in substrate utilization and
reductions in oxidative stress and inflammation may prove beneficial for
exercise performance (Ferreira and Reid 2008); however, to date the
evidence to support an ergogenic effect of green tea is equivocal (Jowko
et al. 2012).
According to a systematic literature review coupled with
meta-analysis, carbohydrate and caffeine coingestion provides a
significant but small effect to improve endurance performance, compared
with carbohydrate alone (Conger et al. 2011). To our knowledge, there
are no published studies that have investigated the effects of coingestion
of carbohydrate and green tea, which contains caffeine, on exercise
performance. The purpose of this study was to examine the acute effects
6
of carbohydrate and green tea coingestion on sprint performance,
oxidative stress, and inflammation. We hypothesized that the combination
of carbohydrate and green tea would increase performance and elevate
anti-oxidant potential activities to attenuate inflammation and muscle
damage.
Materials and methods
Participants
Nine male cyclists (age: 17.6 ± 1.1 years, height: 173.7 ± 3.8 cm, and
body weight: 64.1 ± 5.2 kg) from the Taiwan University of Sport
volunteered to take part in this study. Participants who needed to take any
medication during the study were excluded. The study protocol was
approved by the Human Ethics Committee of the National Taiwan
University of Sport before the start of this study.
Preparation of green tea and determination of caffeine, gallic acid
(GA), and catechin compositions of green tea
Dried nonfermented green tea leaves (Pi-Lo-Chun green tea) were
purchased from Ten Ren Tea Company (Taipei, Taiwan). Extraction was
7
carried out by soaking 20 g of green tea leaves in 600 mL of distilled
water at 25 °C for 24 h. These infusions were then filtered through a tea
strainer. The quantification of caffeine, GA, and catechin compositions in
green tea infusions were performed as described before (Lin et al. 2014).
The concentrations of the caffeine, GA, and catechin compositions in the
cold-prepared green tea were caffeine, 688.3 μg/mL; GA, 117.5 μg/mL;
(–)-epigallocatechin (EGC), 1155.3 μg/mL; (+)-catechin, 90.1 μg/mL;
(–)-epicatechin, 228.6 μg/mL; (–)-epigallocatechin gallate (EGCG),
1030.3 μg/mL; (–)-epicatechin gallate (ECG), 137.4 μg/mL, respectively.
Experimental design
A placebo-controlled, crossover design was used. Following the
familiarization session, all cyclists completed a high-intensity
experimental session. On arrival to the laboratory at 15:00 hours, cyclists
provided a baseline blood sample (pre-exercise) and then completed a
30-min warm-up. The experimental procedure is outlined
diagrammatically in Fig. 1. At each experimental session participants
ingested a water-based beverage, in a counterbalanced order, of either
caffeine (6 mg/kg body mass) and catechin (22 mg/kg body mass) with
8
glucose (230 mg/kg body mass) and fructose (110 mg/kg body mass)
(TEA), or glucose (230 mg/kg body mass) and fructose (110 mg/kg body
mass) (CHO) (Currell and Jeukendrup 2008). The high-intensity interval
training session consisted of 3 exercise sets, which consisted of 8 all-out
repetitions of a 100-m 15% grade climb on the cyclist’s own bicycle.
RPE on a 6 to 20 Borg scale (Borg 1982) were recorded at the end of
each repetition. The required time to complete the 100-m uphill sprint
cycling and RPE in each repetition of each set were recorded and then
averaged among the 3 sets. The recovery period between each repetition
involved cycling on the flat/downhill for 700 m. After set 1 and after set 2,
cyclists had a 10-min rest period where they ingested 250 mL of TEA or
CHO. All participants were asked to rest (abstain from any exercise) till
the next morning’s blood sample was drawn in a fasting state following
overnight recovery and prior to starting any physical activity that day.
Blood samples were taken pre-exercise, 10 min following set 3 exercise,
and after a 14-h recovery period. Experimental sessions were conducted
at the same time of day for each individual to control for diurnal variation.
Experimental trials were separated by 7 days. Participants were asked to
maintain their usual diet and lifestyle during the study period.
9
Blood collection
Blood samples were collected via an indwelled cannula (20G). Ten
milliliters of blood was collected into a heparinized tube at each sampling
time. Hematological analysis was performed immediately after the
samples were taken. The remaining samples were centrifuged at 1500g
(Eppendorf 5810, Hamburg, Germany) to separate plasma. The aliquoted
plasma samples were stored at –70 °C until analysis.
Measurement of blood cell populations and plasma biochemical
markers
The research personnel who conducted the analysis were blind to the
sample groups. Blood cell count, hemoglobin concentration, and
hematocrit in whole blood were determined using a hematology analyzer
(KX-21N, Sysmex Corporation, Kobe, Japan) to correct for the change in
plasma volume. Changes in plasma volume during the acute bout of
exercise were calculated using the method outlined by Dill and Costill
(1974). Plasma glucose, lactate, cortisol, and testosterone concentrations
and creatine kinase activity were measured with an automatic analyzer
10
(Hitachi 7020, Tokyo, Japan) using commercial kits (Randox, Antrim,
UK). Plasma glucose, cortisol, and testosterone concentrations were
determined pre- and postexercise only.
Measurement of cytokines and oxidative stress markers
Plasma concentrations of interleukin (IL)-1
,
adiponectin (R&D Systems, Minneapolis, USA), IL-10, IL-12p40 (BD
Biosciences, N.J., USA), myeloperoxidase (MPO) (Hycult Biotechnology,
Frontstraat, the Netherlands), and thioredoxin (TRX) (Immuno-Biological
Laboratories Co. Ltd., Tokyo, Japan) were measured using enzymelinked
immunosorbent assay kits. Plasma concentrations of derivatives of
reactive oxygen metabolites (d-ROMs) and biological antioxidant
potential (BAP) were measured using assay kits (Diacron, Grosseto,
Italy).
Statistical analysis
All values were expressed as means ± SD. The changes in exercise
performance, blood cell populations, plasma levels of biochemical, and
immunoendocrine indices were analyzed by a 2-way ANOVA (group ×
11
time) with Bonferroni post hoc testing. Sprint times and RPE for each
sprint were analyzed by a 3-way ANOVA (group × sprint × set). The
analysis was performed with SPSS for Windows 15.0 (SPSS, Chicago,
Ill., USA). A p value less than 0.05 was considered statistically
significant.
Results
Effects of carbohydrate and green tea coingestion on performance
Time was significantly slower across sprints (p = 0.001) and across
each set (p = 0.008) but there was no significant interaction of group ×set
× sprint (p = 0.285). RPE was significantly increased across sprints (p =
0.001) and sets (p < 0.0001) but there was no significant interaction of
group × set × sprint (p = 0.137) (Table 1).
Effects of carbohydrate and green tea coingestion on blood cell
populations, muscle damage markers, and related cytokines
There was a significant main effect of time on leukocyte (p < 0.0001)
and neutrophil counts (p < 0.0001), with cell counts significantly
increased in both groups pre- to postexercise (both p < 0.0001), and from
12
postexercise to 14 h (both p < 0.0001) (Table 2). There was no significant
interaction of group by time for leukocyte (p = 0.923), while this
approached significance for neutrophils (p = 0.054) where postexercise
neutrophil counts were lower in the TEA group compared with the CHO
group. There was a significant effect of time (p = 0.003) and interaction
of group by time (p = 0.023) for lymphocyte count (Table 2). While
lymphocyte count was unchanged in the TEA group it was significantly
decreased from pre- to postexercise in the CHO group (p < 0.0001), and
significantly lower than the TEA group postexercise (p < 0.001).
There was a significant main effect of time on creatine kinase activity
and myoglobin concentration (p < 0.0001) with the levels significantly
elevated in both groups postexercise and 14 h postexercise when
compared with pre-exercise (all p < 0.0001) (Table 2). IL-6 and IL-10
also increased postexercise in both groups (p < 0.007) but there was no
significant interaction of group by time (p > 0.199) (Table 2). IL-1β,
tumor necrosis factor-α, and IL-12p40 were not significantly changed
over time or as a result of the beverage (all p > 0.063). Plasma
adiponectin concentration also remained unchanged (p > 0.256) (Table
2).
13
Effects of carbohydrate and green tea coingestion on glucose and
lactate
There was a significant main effect of time (p = 0.048) on plasma
glucose concentration and a significant interaction of group by time (p <
0.01) (Fig. 2a). Glucose concentration decreased significantly
postexercise in the TEA group (p = 0.019) while it was not significantly
changed from pre-exercise in the CHO group (p = 0.437).
There was a significant main effect of time (p < 0.0001) and group (p
= 0.049) for blood lactate concentration while the interaction of group by
time approached significance (p = 0.056) (Fig. 2b). Lactate
concentrations were significantly elevated postexercise and at 14 h
postexercise in both groups (p < 0.0002). Postexercise lactate
concentration was significantly greater in the TEA group compared with
the CHO group (p < 0.01).
Effects of carbohydrate and green tea coingestion on cortisol and
testosterone
There was a significant effect of time for plasma cortisol
14
concentration (p = 0.027) but no significant main effect of group (p =
0.893) or interaction of group by time (p = 0.357) (Fig. 3a). Postexercise
cortisol concentrations were significantly elevated in the TEA group but
were not significantly changed in the CHO group (p = 0.387).
Plasma testosterone level was significantly different across time (p =
0.001) and there was a significant interaction of group by time (p = 0.016)
(Fig. 3b). Postexercise testosterone concentration was decreased from
pre-exercise in the CHO group (p = 0.001) but not the TEA group (p =
0.450).
Effects of carbohydrate and green tea coingestion on oxidative stress
and antioxidant capacity markers
BAP and d-ROMs were significantly different over time (p < 0.004)
but not between groups (p > 0.22) (Fig. 4a, 4b). d-ROMs were elevated
from pre-exercise to postexercise (p < 0.05) and returned to preexercise
levels by 14 h postexercise. TRX and MPO were not significantly
different across time or between groups and there was no significant
interaction of time by group (all p > 0.057) (Fig. 4c, 4d).
15
Discussion
To our knowledge, this is the first investigation to examine the effects
of acute carbohydrate and green tea (caffeine and catechins) coingestion
on sprint cycling performance, and associated oxidative stress and
immunoendocrine responses to exercise. The addition of green tea to
carbohydrate did not significantly influence cycling sprint performance or
postexercise markers of oxidation, inflammation, and muscle damage.
The ingestion of caffeine and catechins during sprint cycling, however,
did maintain postexercise lymphocyte and testosterone concentrations
when compared with carbohydrate ingestion alone. While ingestion of
green tea may prevent a decrease in lymphocyte and testosterone
concentrations postexercise, potentially proving beneficial for recovery, it
does not benefit acute cycling sprint performance in comparison with
carbohydrate alone.
The effect of acute green tea ingestion on sprint performance is
unknown although performance benefits have been proposed because of
the caffeine content of green tea, although the effects of caffeine on sprint
performance are inconclusive, particularly when compared with the
effects of carbohydrate. Repeat intermittent cycling sprint performance
16
(4–10 s) has been reported to be unaffected by the ingestion of high doses
of caffeine (6 mg/kg) at 1 h prior to exercise when compared with
carbohydrate (Glaister et al. 2012; Lee et al. 2014a, 2014b), whereas
running sprint performance (12 × 30 m; repeated at 35-s intervals) is
improved under the same conditions (Glaister et al. 2008). In the present
study, cycling sprint performance was not enhanced with the ingestion of
green tea containing 6 mg/kg of caffeine. While the green tea was taken
following the commencement of exercise, a study by Paton et al. (2010)
reported a reduction in fatigue over 4 sets of 5 × 30-s cycling sprints
following ingestion of caffeine via a chewing gum immediately before
exercise. Longer term supplementation with a green tea extract (4 weeks)
not containing caffeine similarly has been shown to have no benefit for
cycling sprint performance (Jowko et al. 2015). The benefits of longer
term green tea (containing caffeine) ingestion on sprint performance are
unknown; however, acute ingestion does not appear to benefit repeat
cycling sprints.
Previous investigations have shown that green tea extracts improve
insulin sensitivity and stimulate glucose uptake (Takahashi et al. 2014;
Venables et al. 2008), while increasing fat oxidation during
17
moderate-intensity exercise (Venables et al. 2008). Blood glucose levels
decreased significantly in the TEA group immediately following exercise
although the mechanism for this is unclear. High-intensity exercise is
usually associated with increased blood glucose and blood lactate levels
(Peake et al. 2014), but only blood lactate was increased postexercise and
remained elevated 14 h postexercise in both groups. While the
mechanism for this is unclear, blood lactate levels may have remained
above pre-exercise concentrations because of participants’ fasting states
at 14 h postexercise, where adipocytes have been shown to produce
lactate, which may increase with fasting (Newby et al. 1990). While
adiponectin may inhibit hepatic glucose metabolism and enhance glucose
uptake in skeletal muscle, potentially reducing blood glucose
concentration, adiponectin level was not significantly influenced by green
tea ingestion. The metabolic impact of green tea on substrate utilization in
athletes requires further investigation.
Testosterone concentrations have been reported to increase (Tanner et
al. 2014) or remain unchanged in males (Hoffman et al. 1997) in response
to repeat high-intensity sprint exercise although to date no published
studies have investigated changes in testosterone concentration following
18
green tea ingestion in healthy humans. In the present study, testosterone
concentration was significantly decreased after exercise in the
carbohydrate only group while levels were maintained with the
coingestion of green tea and carbohydrate. A bolus ingestion of 75 g
glucose has been shown to decrease total and free testosterone
concentration (Caronia et al. 2013). Although carbohydrate ingestion in
the present study was the same in both groups (glucose 230 mg/kg body
mass and fructose 110 mg/kg body mass), the addition of green tea to
carbohydrate may have reduced carbohydrate uptake from the gut
(Krezowski et al. 1986). Studies in rats, however, suggest that infusion of
green tea compounds such as EGCG reduce circulating testosterone
concentration, while in vitro models have shown increased testosterone
secretion by rat Leydig cells co-cultured with various catechins (Yu et al.
2010). While the effect of catechins on testosterone in healthy males is
yet to be determined, it is possible that caffeine contained within green
tea may influence testosterone concentration. Acute administration of a
similar dose (240 mg) of caffeine to that contained in the green tea of the
present study has previously been shown to elevate testosterone
concentration following repeat 30-s sprints when compared with a
19
sugar-free chewing gum (Paton et al. 2010). Testosterone concentration is
often lowered following periods of heavy training (Hakkinen and
Pakarinen 1993) and as testosterone may promote glycogen synthase
activity (van Breda et al. 1993) and creatine phosphate restoration (Sutton
et al. 1973), lower levels may be associated with slower recovery from
intense exercise. The longer term (greater than 12 h) recovery benefits of
green tea should be determined in future investigations.
Dietary supplementation with catechins may modulate the oxidative
stress response (Yiannakopoulou 2013). In mice that completed a
downhill run supplementation with catechins for 3 weeks attenuated
muscle damage and associated increases in gastrocnemius lipid peroxides,
MPO, and carbonylated protein content (Haramizu et al. 2013). Longer
term (4 weeks) supplementation with a green tea extract in healthy males
increased resting plasma total antioxidant status but had no effect on
antioxidant enzyme activity or other markers of oxidative stress following
1 set of bench press and 1 set of back squat (60% 1-repetition maximum)
to fatigue (Jowko et al. 2011). While longer term dosing may upregulate
antioxidant defenses (Jowko et al. 2011), acute supplementation has been
shown to impact upon endogenous metabolites, with elevations in
20
circulating EGCG, EGC, and ECG at 1 h following green tea ingestion
(Fung et al. 2013). In the present study, green tea ingestion following the
commencement of exercise increased antioxidant potential (BAP)
immediately following sprint cycling exercise, although this did not
dampen postexercise increases in hydroperoxides (d-ROMs) or measured
muscle damage markers across the recovery period. Similarly, Jowko et
al. (2012) reported no difference in exercise-related markers of oxidative
stress or muscle damage following an acute dose of green tea polyphenols
(640 mg) 90 min prior to a muscular endurance test in soccer players.
While regular green tea consumption may influence antioxidant status,
acute ingestion does not appear to dampen markers of oxidative stress or
muscle damage following sprint cycling.
As has previously been shown with strenuous exercise, IL-6 and
IL-10 were elevated following the cycling sprints, although systemic
concentrations of cytokines were not influenced by the combined
ingestion of green tea and carbohydrate. While there was a trend for the
dampening of the postexercise increase in neutrophil count with green tea
ingestion compared with carbohydrate alone (p = 0.054), the immediate
postexercise reduction in lymphocytes was significantly suppressed. An
21
increase in neutrophil count and decrease in lymphocyte count is
associated with prolonged, heavy-endurance exercise (Murakami et al.
2010) and may be related to inflammatory mediated immunosuppression.
The impact of the alterations in neutrophil and lymphocyte count
immediately following sprinting exercise are unclear as muscle damage
markers and inflammatory markers were similar following ingestion of
green tea and carbohydrate or carbohydrate alone. It is possible that
longer term green tea ingestion may prove beneficial during periods of
training overload where immune function may be suppressed.
In conclusion, while acute green tea ingestion attenuates the
postexercise decrease in lymphocyte and testosterone concentrations, it
does not appear to benefit cycling sprint performance or reduce markers
of oxidation and inflammation when compared with carbohydrate alone.
The optimum timing and dose of green tea ingestion for potential
anti-inflammatory and anti-oxidant effects in athletes remains to be
explored.
Acknowledgements
We warmly thank the coach, Jui-Te Hsu, and all the cyclic athletes
22
for their patience and participation in this study. This study was supported
by a grant from National Science Council (NSC)
101-2628-H-028-002-MY3 granted by National Science Council,
Republic of China; from the Waseda Institute of Sports Nutrition; and a
Grant-in Aid for Scientific Research (A) from the Ministry of Education,
Culture, Sports, Science, and Technology, Japan (23240097-15H01833).
We thank Pei-Yu Shih for expert technical assistance.
References
Astorino, T.A., Cottrell, T., Lozano, A.T., Aburto-Pratt, K., and Duhon, J.
2012. Increases in cycling performance in response to caffeine
ingestion are repeatable. Nutr. Res. 32(2): 78–84.
Beaven, C.M., Maulder, P., Pooley, A., Kilduff, L., and Cook, C. 2013.
Effects of caffeine and carbohydrate mouth rinses on repeated sprint
performance. Appl. Physiol. Nutr. Metab. 38(6): 633–637.
Bogdanski, P., Suliburska, J., Szulinska, M., Stepien, M., Pupek-Musialik,
D., and Jablecka, A. 2012. Green tea extract reduces blood pressure,
inflammatory biomarkers, and oxidative stress and improves
parameters associated with insulin resistance in obese, hypertensive
23
patients. Nutr. Res. 32(6): 421–427.
Borg, G.A. 1982. Psychophysical bases of perceived exertion. Med. Sci.
Sports Exerc. 14(5): 377–381.
Burke, L.M. 2008. Caffeine and sports performance. Appl. Physiol. Nutr.
Metab. 33(6): 1319–1334.
Caronia, L.M., Dwyer, A.A., Hayden, D., Amati, F., Pitteloud, N., and
Hayes, F.J. 2013. Abrupt decrease in serum testosterone levels after
an oral glucose load in men: implications for screening for
hypogonadism. Clin. Endocrinol. 78(2): 291–296.
Chacko, S.M., Thambi, P.T., Kuttan, R., and Nishigaki, I. 2010.
Beneficial effects of green tea: a literature review. Chin. Med. 5: 13
Conger, S.A., Warren, G.L., Hardy, M.A., and Millard-Stafford, M.L.
2011. Does caffeine added to carbohydrate provide additional
ergogenic benefit for endurance? Int. J. Sport Nutr. Exerc. Metab.
21(1): 71–84.
Cooper, R., Naclerio, F., Allgrove, J., and Larumbe-Zabala, E. 2014.
Effects of a carbohydrate and caffeine gel on intermittent sprint
performance in recreationally trained males. Eur. J. Sport Sci. 14(4):
353–361.
24
Costill, D.L., and Hargreaves, M. 1992. Carbohydrate nutrition and
fatigue. Sports Med. 13(2): 86–92.
Currell, K., and Jeukendrup, A.E. 2008. Superior endurance performance
with ingestion of multiple transportable carbohydrates. Med. Sci.
Sports Exerc. 40(2): 275–281.
Dill, D.B., and Costill, D.L. 1974. Calculation of percentage changes in
volumes of blood, plasma, and red cells in dehydration. J. Appl.
Physiol. 37(2): 247–248.
Dulloo, A.G., Duret, C., Rohrer, D., Girardier, L., Mensi, N., Fathi, M., et
al. 1999. Efficacy of a green tea extract rich in catechin polyphenols
and caffeine in increasing 24-h energy expenditure and fat oxidation
in humans. Am. J. Clin. Nutr. 70(6): 1040–1045.
Ferreira, L.F., and Reid, M.B. 2008. Muscle-derived ROS and thiol
regulation in muscle fatigue. J. Appl. Physiol. 104(3): 853–860.
Fung, S.T., Ho, C.K., Choi, S.W., Chung, W.Y., and Benzie, I.F. 2013.
Comparison of catechin profiles in human plasma and urine after
single dosing and regular intake of green tea (Camellia sinensis). Br. J.
Nutr. 109(12): 2199–2207.
Gant, N., Ali, A., and Foskett, A. 2010. The influence of caffeine and
25
carbohydrate coingestion on simulated soccer performance. Int. J.
Sport Nutr. Exerc. Metab. 20(3): 191–197.
Glaister, M., Howatson, G., Abraham, C.S., Lockey, R.A., Goodwin, J.E.,
Foley, P., and McInnes, G. 2008. Caffeine supplementation and
multiple sprint running performance. Med. Sci. Sports Exerc. 40(10):
1835–1840.
Glaister, M., Patterson, S.D., Foley, P., Pedlar, C.R., Pattison, J.R., and
McInnes, G. 2012. Caffeine and sprinting performance: dose
responses and efficacy. J. Strength Cond. Res. 26(4): 1001–1005.
Goldstein, E.R., Ziegenfuss, T., Kalman, D., Kreider, R., Campbell, B.,
Wilborn, C., et al. 2010. International society of sports nutrition
position stand: caffeine and performance. J. Int. Soc. Sports Nutr. 7(1):
5. doi:10.1186/1550-2783-7-5.
Hakkinen, K., and Pakarinen, A. 1993. Acute hormonal responses to two
different fatiguing heavy-resistance protocols in male athletes. J. Appl.
Physiol. 74(2): 882–887.
Haramizu, S., Ota, N., Hase, T., and Murase, T. 2013. Catechins suppress
muscle inflammation and hasten performance recovery after exercise.
Med. Sci. Sports Exerc. 45(9): 1694–1702.
26
Higgins, J.P., Tuttle, T.D., and Higgins, C.L. 2010. Energy beverages:
content and safety. Mayo Clin. Proc. 85(11): 1033–1041.
Hoffman, J.R., Falk, B., Radom-Isaac, S., Weinstein, Y., Magazanik, A.,
Wang, Y., and Yarom, Y. 1997. The effect of environmental
temperature on testosterone and cortisol responses to high intensity,
intermittent exercise in humans. Eur. J. Appl. Physiol. Occup. Physiol.
75(1): 83–87.
Hulston, C.J., and Jeukendrup, A.E. 2008. Substrate metabolism and
exercise performance with caffeine and carbohydrate intake. Med. Sci.
Sports Exerc. 40(12): 2096–2104. do
Ichinose, T., Nomura, S., Someya, Y., Akimoto, S., Tachiyashiki, K., and
Imaizumi, K. 2011. Effect of endurance training supplemented with
green tea extract on substrate metabolism during exercise in humans.
Scand. J. Med. Sci. Sports, 21(4): 598–605.
Jeukendrup, A.E. 2011. Nutrition for endurance sports: marathon,
triathlon, and road cycling. J. Sports Sci. 29(Suppl. 1): S91–S99.
Jowko, E., Sacharuk, J., Balasinska, B., Ostaszewski, P., Charmas, M.,
and Charmas, R. 2011. Green tea extract supplementation gives
protection against exercise-induced oxidative damage in healthy men.
27
Nutr. Res. 31(11): 813–821.
Jowko, E., Sacharuk, J., Balasinska, B., Wilczak, J., Charmas, M.,
Ostaszewski, P., and Charmas, R. 2012. Effect of a single dose of
green tea polyphenols on the blood markers of exercise-induced
oxidative stress in soccer players. Int. J. Sport Nutr. Exerc. Metab.
22(6): 486–496.
Jowko, E., Dlugolecka, B., Makaruk, B., and Cieslinski, I. 2015. The
effect of green tea extract supplementation on exercise-induced
oxidative stress parameters in male sprinters. Eur. J. Nutr. 54(5): 783–
791.
Krezowski, P.A., Nuttall, F.Q., Gannon, M.C., and Bartosh, N.H. 1986.
The effect of protein ingestion on the metabolic response to oral
glucose in normal individuals. Am. J. Clin. Nutr. 44(6): 847–856.
Lee, C.L., Cheng, C.F., Astorino, T.A., Lee, C.J., Huang, H.W., and
Chang, W.D. 2014a. Effects of carbohydrate combined with caffeine
on repeated sprint cycling and agility performance in female athletes.
J. Int. Soc. Sports Nutr. 11: 17.
Lee, C.L., Cheng, C.F., Lee, C.J., Kuo, Y.H., and Chang, W.D. 2014b.
Co-ingestion of caffeine and carbohydrate after meal does not
28
improve performance at highintensity intermittent sprints with short
recovery times. Eur. J. Appl. Physiol. 114(7): 1533–1543.
Lin, S.P., Li, C.Y., Suzuki, K., Chang, C.K., Chou, K.M., and Fang, S.H.
2014. Green tea consumption after intense taekwondo training
enhances salivary defense factors and antibacterial capacity. PLoS
One, 9(1): e87580.
Murakami, S., Kurihara, S., Titchenal, C.A., and Ohtani, M. 2010.
Suppression of exercise-induced neutrophilia and lymphopenia in
athletes by cystine/theanine intake: a randomized, double-blind,
placebo-controlled trial. J. Int. Soc. Sports Nutr. 7(1): 23.
Newby, F.D., Wilson, L.K., Thacker, S.V., and DiGirolamo, M. 1990.
Adipocyte lactate production remains elevated during refeeding after
fasting. Am. J. Physiol. 259(6): E865–E871.
Paton, C.D., Lowe, T., and Irvine, A. 2010. Caffeinated chewing gum
increases repeated sprint performance and augments increases in
testosterone in competitive cyclists. Eur. J. Appl. Physiol. 110(6):
1243–1250.
Peake, J.M., Tan, S.J., Markworth, J.F., Broadbent, J.A., Skinner, T.L.,
and Cameron-Smith, D. 2014. Metabolic and hormonal responses to
29
isoenergetic high-intensity interval exercise and continuous
moderate-intensity exercise. Am. J. Physiol. Endocrinol. Metab.
307(7): E539–E552.
Pedersen, D.J., Lessard, S.J., Coffey, V.G., Churchley, E.G., Wootton,
A.M., Ng, T., et al. 2008. High rates of muscle glycogen resynthesis
after exhaustive exercise when carbohydrate is coingested with
caffeine. J. Appl. Physiol. 105(1): 7–13.
Phillips, S.M., Findlay, S., Kavaliauskas, M., and Grant, M.C. 2014. The
influence of serial carbohydrate mouth rinsing on power output
during a cycle sprint. J. Sports Sci. Med. 13(2): 252–258.
Roberts, S.P., Stokes, K.A., Trewartha, G., Doyle, J., Hogben, P., and
Thompson, D. 2010. Effects of carbohydrate and caffeine ingestion
on performance during a rugby union simulation protocol. J. Sports
Sci. 28(8): 833–842.
Rumpler, W., Seale, J., Clevidence, B., Judd, J., Wiley, E., Yamamoto, S.,
et al. 2001. Oolong tea increases metabolic rate and fat oxidation in
men. J. Nutr. 131(11): 2848–2852. PMID:11694607.
Sutton, J.R., Coleman, M.J., Casey, J., and Lazarus, L. 1973. Androgen
responses during physical exercise. Br. Med. J. 1(5852): 520–522.
30
Takahashi, M., Miyashita, M., Suzuki, K., Bae, S.R., Kim, H.K.,
Wakisaka, T., et al. 2014. Acute ingestion of catechin-rich green tea
improves postprandial glucose status and increases serum thioredoxin
concentrations in postmenopausal women. Br. J. Nutr. 112(9): 1542–
1550.
Tanner, A.V., Nielsen, B.V., and Allgrove, J. 2014. Salivary and plasma
cortisol and testosterone responses to interval and tempo runs and a
bodyweight-only circuit session in endurance-trained men. J. Sports
Sci. 32(7): 680–689.
van Breda, E., Keizer, H.A., Geurten, P., van Kranenburg, G., Menheere,
P.P., Kuipers, H., and Glatz, J.F. 1993. Modulation of glycogen
metabolism of rat skeletal muscles by endurance training and
testosterone treatment. Pflugers Arch. 424(3–4): 294–300.
Venables, M.C., Hulston, C.J., Cox, H.R., and Jeukendrup, A.E. 2008.
Green tea extract ingestion, fat oxidation, and glucose tolerance in
healthy humans. Am. J. Clin. Nutr. 87(3): 778–784.
Warren, G.L., Park, N.D., Maresca, R.D., McKibans, K.I., and
Millard-Stafford, M.L. 2010. Effect of caffeine ingestion on muscular
strength and endurance: a meta-analysis. Med. Sci. Sports Exerc.
31
42(7): 1375–1387.
Yiannakopoulou, E. 2013. Targeting oxidative stress response by green
tea polyphenols: clinical implications. Free Radic. Res. 47(9): 667–
671.
Yu, P.L., Pu, H.F., Chen, S.Y., Wang, S.W., and Wang, P.S. 2010.
Effects of catechin, epicatechin and epigallocatechin gallate on
testosterone production in rat leydig cells. J. Cell. Biochem. 110(2):
333–342.
32
Tables
33
Figures
Fig. 1
Scheme of exercise and sampling protocol of the study. Blood sampling
was carried out at 3 time-points: immediately pre-exercise (Pre), 10
min postexercise (Post), and 14 h following exercise (Post-14 h).
34
Fig. 2
Effects of carbohydrate and green tea coingestion on the concentrations
of blood glucose (a) and lactate (b) of CHO and TEA groups at
various time-points. The blood glucose levels were monitored at 2
time-points: pre-exercise (white bar) and postexercise (slashed bar);
meanwhile, the lactate levels were measures at 3 time-points:
pre-exercise (white bar), post-exercise (slashed bar), and 14 h
following exercise (grey bar). CHO, carbohydrate only; TEA, green
tea and carbohydrate. *, Significantly different from pre-exercise
within group (p < 0.05). †, Significantly different from postexercise
within group (p < 0.05).
35
Fig. 3
Effects of carbohydrate and green tea coingestion on the concentrations
of blood cortisol (a) and testosterone (b) of CHO and TEA groups at
various time-points. The blood cortisol and testosterone levels were
measured pre-exercise (white bar) and post-exercise (slashed bar).
CHO, carbohydrate only; TEA, green tea and carbohydrate. *,
Significantly different from pre-exercise within group (p < 0.05).
36
Fig. 4
Effects of carbohydrate and green tea coingestion on the concentrations
of blood biological antioxidant potential (BAP) (a), derivatives of
reactive oxygen metabolites (d-ROMs) (b), myeloperoxidase (MPO)
(c), and thioredoxin (TRX) (d) of CHO and TEA groups at
pre-exercise (white bar), postexercise (slashed bar), and 14 h
following exercise (grey bar). CHO, carbohydrate only; TEA, green
tea and carbohydrate. *, Significantly different from pre-exercise
within group (p < 0.05). †, Significantly different from postexercise
within group (p < 0.05).
37