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486
International Journal of Sport Nutrition and Exercise Metabolism, 2012, 22, 486 -496
© 2012 Human Kinetics, Inc.
Jówko, Sacharuk, M. Charmas, and R. Charmas are with the
Faculty of Physical Education and Sport in Biala Podlaska,
University of Physical Education, Warsaw, Poland. Balasinska,
Wilczak, and Ostaszewski are with the Faculty of Veterinary
Medicine, Warsaw Agricultural University, Warsaw, Poland.
Effect of a Single Dose of Green Tea Polyphenols
on the Blood Markers of Exercise-Induced Oxidative Stress
in Soccer Players
Ewa Jówko, Jaroslaw Sacharuk, Bozena Balasinska, Jacek Wilczak,
Malgorzata Charmas, Piotr Ostaszewski, and Robert Charmas
Purpose: To evaluate the effect of acute ingestion of green tea polyphenols (GTP) on blood markers of oxi-
dative stress and muscle damage in soccer players exposed to intense exercise. Methods: This randomized,
double-blinded study was conducted on 16 players during a general preparation period, when all athletes
participated in a strength-training program focused on the development of strength endurance. After inges-
tion of a single dose of GTP (640 mg) or placebo, all athletes performed an intense muscle-endurance test
consisting of 3 sets of 2 strength exercises (bench press, back squat) performed to exhaustion, with a load at
60% 1-repetition maximum and 1-min rests between sets. Blood samples were collected preexercise, 5 min
after the muscle-endurance test, and after 24 hr of recovery. Blood plasma was analyzed for the concentrations
of thiobarbituric acid–reacting substances (TBARS), uric acid (UA), total catechins, total antioxidant status
(TAS), and activity of creatine kinase (CK); at the same time, erythrocytes were assayed for the activity of
superoxide dismutase (SOD). Results: In both groups, plasma TBARS, UA, and TAS increased signicantly
postexercise and remained elevated after a 24-hr recovery period. SOD activity in erythrocytes did not change
signicantly in response to the muscle-endurance test, whereas in both groups plasma CK activity increased
signicantly after 24 hr of recovery. Acute intake of GTP cased a slight but signicant increase in total plasma
catechins. However, GTP was found not to exert a signicant effect on measured parameters. Conclusions:
Acute ingestion of GTP (640 mg) does not attenuate exercise-induced oxidative stress and muscle damage.
Keywords: catechins, antioxidants, oxidation-reduction balance
The generation of reactive oxygen species (ROS) is
an inevitable consequence of normal cellular metabolism.
The body defends itself against their detrimental activity
by means of the antioxidant defense system, the objec-
tive of which is to render ROS harmless. The system
is composed of antioxidant enzymes including, among
others, superoxide dismutase (SOD) and glutathione
peroxidase, as well as nonenzymatic antioxidants includ-
ing glutathione, coenzyme Q10, uric acid (UA), vitamins,
and polyphenols (Lamprecht, Greilberger, Schwaberger,
Hofmann, & Oettl, 2008). Under conditions of intensied
ROS production, the antioxidant defense system may
prove inefcient, which in turn leads to oxidative stress,
a state induced by the imbalance between antioxidative
and pro-oxidative processes (Fisher-Wellman & Bloomer,
2009).
Strenuous physical exercise is one of the factors
alleged to induce oxidative stress. Under conditions of
exercise-induced oxidative stress, increased oxidation of
cell constituents—DNA, lipids, and proteins—has been
observed (Banerjee, Mandal, Chanda, & Chakraborti,
2003). The oxidative stress induced by acute physical
exercise may lead to aerobic damage of muscle tissue,
consequently intensifying muscle soreness and diminish-
ing exercise performance (Lamprecht et al., 2008).
It is suggested that lipids are more sensitive to oxi-
dative damage than proteins are (Morillas-Ruiz, Villegas
Garcia, Lopez, Vidal-Guevara, & Zafrilla, 2006). ROS
release causes lipid peroxidation of polyunsaturated fatty
acids in biological membranes and blood. Malondialde-
hyde, a by-product of lipid peroxide, and thiobarbituric
acid reactive substances (TBARS; indirect assay used to
measure aldehyde products, primarily malondialdehyde,
formed via decomposition of lipid hydroperoxides)
have been the most frequently used markers of oxida-
tive tissue damage during exercise (Fisher-Wellman
& Bloomer, 2009). In fact, increased oxidative-stress
biomarkers have been observed not only after aerobic
exercise (exhaustive long-distance cycling and running)
but also after anaerobic exercise (supramaximal sprints
or strength-type exercises; Bloomer & Goldfarb, 2004;
García-López et al., 2007). It is common knowledge that
intensive anaerobic exercise induces oxidative stress,
www.IJSNEM-Journal.com
ORIGINAL RESEARCH
Green Tea Polyphenols and Exercise-Induced Oxidative Stress 487
mainly owing to an increased—under conditions of
ischemia or reperfusion—activity of xanthine oxidase,
an enzyme that is a signicant source of ROS (Gold-
farb, Bloomer, & McKenzie, 2005). In addition, during
weight-lifting exercises cells of the skeletal muscles are
subjected to microinjuries. In these areas an accumula-
tion of inltrated phagocytic cells, neutrophils, and
macrophages occurs, while NADPH oxidase localized
in the plasma membrane of the activated phagocytes
constitutes an additional source of free oxygen radicals
(Kon et al., 2007).
Athletes are especially exposed to oxidative stress
(Alessio, 1993). While regular physical training, espe-
cially of the endurance type, may enhance the body’s
antioxidant defense by various factors—for example,
by increasing resting activity of antioxidant enzymes in
erythrocytes (Metin et al., 2003)—the pursuit of optimal
results in competitive sports requires that athletes often
undertake strenuous training under conditions of insuf-
cient postexercise restitution. This may, however, lead
to overtraining. What is more, the unfavorable changes
occurring in metabolism under conditions of postexercise
oxidative stress may negatively affect the health of an
athlete. Taking this into account, some authors suggest
that supporting athletes with antioxidants could alleviate
the negative effects of oxidative stress (Ho, Li, Chen, &
Hsu, 2007). However, it should be mentioned that preven-
tion of ROS formation by antioxidant supplementation
may delay the recovery of muscle function (Teixeira,
Valente, Casal, Marques, & Moreira, 2009) and even
hamper training-induced adaptations (Gomez-Cabrera
et al., 2008).
Although some surveys report no effects of antioxi-
dant administration on the postexercise level of plasma
markers of oxidative stress (Gaeini, Rahnama, & Hame-
dinia, 2006; McAnulty et al., 2008), and in some cases
even demonstrate their pro-oxidative activity (Silva et al.,
2008), numerous other studies have indicated a decrease
in the postexercise oxidative stress in athletes as a result of
long-term (≥14 days) supplementation with antioxidants
(Bonina et al., 2005; Pilaczynska-Szczesniak, Skarpan-
ska-Steinborn, Deskur, Basta, & Horoszkiewicz-Hassan,
2005). In some studies, postexercise oxidative stress
was observed to diminish after a single administration
of antioxidants. One of those surveys demonstrated that
the intake of a polyphenols-rich cocoa drink 2 hr before
intense physical exercise (increasing-intensity test on a
cycle ergometer) effected a signicant reduction in the
postexercise concentration of lipid-peroxidation indices
in blood plasma (Wiswedel et al., 2004). Furthermore,
in research conducted by Zembron-Lacny, Szyszka,
Sobanska, and Pakula (2006), a single dose of vitamin
E was observed to suppress the oxidative stress induced
by a 2000-m laboratory rowing test. In another study
with cyclists, Morillas-Ruiz et al. (2006) demonstrated
a reduction in the extent of aerobic damage to protein
after a strenuous exercise test on a cycle ergometer as a
result of taking a drink enriched with polyphenols (black
grape, raspberry, and red currant) during the exercise.
One of the most popular drinks rich in plant-origi-
nated polyphenols is green tea (Camellia sinensis). It is
well documented that green tea polyphenols (catechins),
apart from having strong antioxidative properties, may
also act as nutritional chemopreventive agents for the
treatment of cancer, atherosclerosis, and neurodegen-
erative diseases (Nicholson, Tucker, & Bameld, 2008).
Few studies are reported in the literature concerning
the effects of green tea polyphenols on blood markers
of exercise-induced oxidative stress. In rats, green
tea consumed for 6.5 weeks lowered renal lipoper-
oxidation after aerobic exercise (Alessio et al., 2002).
In weight-trained men, Panza et al. (2008) observed
protective effects of 7-day intake of green tea on blood
markers of oxidative stress after resistance exercise. How-
ever, there are no reports regarding the effects of acute
ingestion of green tea polyphenols on exercise-induced
oxidative-stress biomarkers.
Therefore, the aim of the current study was to evalu-
ate, in professional soccer players exposed to intense
exercise, the effects of a single dose of green tea poly-
phenols on some noninvasive blood markers of oxidative
stress: plasma total antioxidant status, plasma UA, plasma
TBARS, erythrocyte SOD activity, and plasma creatine
kinase (CK) activity (as a marker of muscle-cell damage).
Materials and Methods
Subjects
Sixteen healthy soccer players from the local club
“Podlasie” were enrolled in the study. All subjects were
nonsmokers and disease-free and had not used drugs,
ergogenic aids, or antioxidant supplements for at least 2
months before the study. Before the experiment, all volun-
teers were informed about the aim of the studies and the
experimental procedure. The study was approved by the
ethical committee of the Academy of Physical Education
in Warsaw, and informed written consent was obtained
from all subjects before the beginning of the study.
The experiment was conducted during a general
preparation period when all soccer players were pursuing
strength training to develop strength endurance. Thus,
as an exercise protocol, a muscle-endurance test was
selected. It included three sets of bench press and back
squat to exhaustion.
Three-day dietary records (2 working days and 1
weekend day) were used to estimate each subject’s aver-
age daily intake of energy, protein, fat, and carbohydrates,
as well as vitamins A, C, and E, at the beginning of the
study. Records were analyzed using the Dietus program
based on the Table of Composition and Nutritional Value
of Foodstuffs (Kunachowicz, Nadolna, Przygoda, &
Iwanow, 2005).
To minimize the effect of other dietary products with
high polyphenol content on the collected data, the sub-
jects were asked to limit fruits, juice, wine, tea, chocolate,
and cocoa for 2 days before the muscle-endurance test
and to refrain from consuming foods other than meat, egg,
488 Jówko et al.
milk products, and water in the evening the day before
the test was conducted.
Seven days before the muscle-endurance test,
each subject was tested for the measurement of a one-
repetition maximum (1-RM) in bench press and back
squat, according to a previously described procedure
(Cramer & Coburn, 2004). The subjects were asked to
cease (discontinue) their training for 2 days before the
muscle-endurance test and 24 hr after it.
Experimental Procedure
The experimental procedure is displayed in Figure 1.
Athletes consumed a standardized breakfast of two rolls
with butter, one slice of ham, and 0.75 L of mineral water
at the university canteen at 6.00 a.m., 3 hr before they
underwent an exercise test. Then, they were randomly
assigned, in a double-blind fashion, to receive two dark
gelatin capsules containing either green tea polyphenols
(GTP group, n = 8) or placebo (PL group, n = 8). Both the
GTP and PL capsules were identical in appearance (i.e.,
size, shape, and color), and they both were manufactured
by Olimp Laboratories (Debica, Poland). The capsules
with GTP were commercially available as Olimp green
tea (Olimp Laboratories, Debica, Poland). Each GTP
capsule contained standardized green tea extract (total of
320 mg polyphenols, including about 250 mg catechins,
of which about 176 mg was epigallocatechin-3-galate-
EGCG) and additional substances (maltodextrin, micro-
crystalline cellulose, magnesium stearate). Thus, two
capsules delivered 640 mg of polyphenols (including 500
mg of catechins). PL capsules contained microcrystalline
cellulose, magnesium stearate, and maltodextrin instead
of GTP. The capsules were administered 2 hr after the
breakfast (at 8.00 a.m.).
One and a half hours after taking the capsules (at
9:30 a.m.), athletes performed the muscle-endurance test
(according to the protocol shown in Figure 2), using a
previously described procedure (Schmitz, Hofheins, &
Lemieux, 2010) that was modied for the purposes of
this experiment. The test consisted of three sets of two
strength exercises (bench press, back squat) performed
to exhaustion, with a load of 60% 1-RM and 1-min rests
between sets. The exercise protocol was performed using
a bar and free weights. Before the test, athletes carried
out a warm-up consisting of bench press and back squat,
both performed in one set of ve repetitions with loads
of 40% 1-RM.
The 90-min interval between capsule consumption
and the muscle-endurance test was adapted from the stud-
ies of Lee et al. (2002), where the highest plasma catechin
content was observed 1.3–1.6 hr after the administration
of a single dose of green tea (394 mg polyphenols).
Blood Sampling and Biochemical
Analysis
Venous blood samples were drawn into heparinized test
tubes from an ulnar vein before the muscle-endurance
test (preexercise), 1.5 hr after oral administration of GTP
and PL capsules; 5 min after completing the muscle-
endurance test (postexercise); and after the 24-hr recovery
period (recovery). Blood samples were centrifuged (for
10 min at 3,000 g at 4 °C) to separate red blood cells from
plasma. Erythrocytes were washed three times with a cold
isotonic saline solution. Both erythrocytes and plasma
were frozen at –80 °C for later analysis.
In addition, capillary blood samples were taken from
a nger prick before the muscle-endurance test and 3 min
after completing the test. Capillary blood was assayed for
the concentration of lactate, as well as for parameters of
acid-base equilibrium.
Red blood cells were analyzed for the activity of
SOD by using a commercially available kit (RanSOD,
Figure 2 — Diagram of the muscle-endurance test.
Figure 1 — Experimental procedure.
Green Tea Polyphenols and Exercise-Induced Oxidative Stress 489
Cat. No. SD 125, Randox, UK). The SOD activity was
measured at 37 °C and expressed in U/g Hb. Hemoglobin
was assessed by a standard cyanmethemoglobin method
using a diagnostic kit (HG 1539, Randox, UK).
Plasma CK activity, as a marker of muscle damage,
was analyzed at 340 nm and 37 °C with a diagnostic kit
(Cat. No. C6512–100, Alpha Diagnostics, USA) and
expressed as U/L.
Plasma UA concentration was analyzed at 520 nm
and 37 °C with a diagnostic kit (Cat. No. K6580-200,
Alpha Diagnostics, USA) and expressed as mg/dl.
The concentrations of TBARS in plasma were
determined as malondialdehyde equivalents according
to the modied method described by Jentzsch, Bach-
mann, Furst, and Biesalski (1996). Plasma TBARS were
determined from a standard curve generated with known
amounts of 1,1,3,3-tetraethoxypropane and expressed as
μmol/L.
Total antioxidant status (TAS) of plasma was mea-
sured by a chromogenic method with the use of a diag-
nostic kit (Cat. No. NX 2332, Randox, UK). Antioxidant
capacity of samples was expressed as millimoles per liter
of Trolox equivalents (6-hydroxy-2,5,7,8-tetramethyl-
chroman-2-carboxylic acid).
Total plasma catechin concentration (epigallocat-
echin, epigallocatechin galate, epicatechin, and epicat-
echin gallate), including unconjugated catechins and
catechins conjugated with glucuronic acid, sulfate, or
glycoside groups, was analyzed according to the method
previously described by Erlund et al. (2000). Briey,
catechin conjugates were hydrolyzed by incubating 1
ml plasma with 110 μl 0.78-M sodium acetate buffer
(pH 4.8), 100 μl 0.1-M ascorbic acid, and 40 μl of a
crude preparation from Helix pomatia containing 4,000
U of B-glucuronidase and 200 U of sulfatase activity
(Type H-2, Sigma) for 17 hr at 37 °C. After incubation,
avonoids were released from protein using solid-phase
extraction. The sample was diluted with 2 ml phosphate
buffer (70 mM, pH 2.4) and added to a Bond Elut C18
solid-phase extraction column (500 mg, Backer) precon-
ditioned with 6 ml methanol and 6 ml phosphate buffer.
The column was washed with 9 ml phosphate buffer and
0.5 ml deionized water. Flavonoids were eluted into a
conical glass tube with 2 ml methanol and dried under
nitrogen stream. All residues were diluted with 200 μl
methanol and used for high-performance liquid chro-
matography (HPLC) connected with electrochemical
detector analysis. The analysis of catechin separation
and contents was made by applying the HPLC system
(Dionex) equipped in the CoulArray electrochemical
detector (ESA Inc.) The separation was conducted on
a Hypersil BDS 150 × 4.6-mm, 5-μm column (Sigma-
Aldrich) at a mobile-phase ow rate of 1.2 ml/min. The
mobile phase consisted of sodium phosphate 50-mM and
metanol (99:1) pH 3.0. The conditions of electrochemical
detection were four electrodes with potentials 400, 500,
600, and 750 mV. The chromatograms were processed
by identifying the compounds on the base of standards
and areas of chromatographic peaks, taking into account
their retention times, as well as the ratio of the peak
area for the dominating electrode to that of neighbor-
ing electrodes. Total plasma catechin concentration was
expressed as ng/ml.
Lactate levels in the capillary blood were determined
using a diagnostic cuvette kit (Dr. Lange, Cat. No. LKM
140, Germany) and Miniphotometer Plus LP 20 (Hach
Lange, Germany). Parameters of acid-base equilibrium
in capillary blood, as pH, base deciency, and anion gap,
and hematocrit were evaluated with the use an automated
analyzer (OMNI-C, Roche Diagnostics, Austria). All
samples were corrected for plasma volume shift accord-
ing to the method of Dill and Costill (1974).
Statistical Analysis
Statistical analysis was performed with the Statistica
v. 6.0 software package. Comparisons between groups
regarding dietary intakes, subject characteristics, and
results of the exercise test were made by applying an
unpaired Student’s t test. Biochemical-parameter data
were analyzed using two-way mixed ANOVA with two
independent variables: group (GTP vs. placebo) and time
(pre- vs. postexercise vs. 24-hr recovery). If signicant
differences in ANOVA tests were observed, data were
analyzed with a near-infrared post hoc test for multiple
comparisons. All values were reported as M ± SD. The
level of statistical signicance was set at p < .05.
Results
The physical characteristics of the athletes and results
obtained in the muscle-endurance test are shown in Table
1. Subjects in both groups were similar in regard to mean
age, height, body mass, body-mass index, and years of
training. In addition, results obtained in the muscle-
endurance test—total number of repetitions in three sets
of bench press or back squat—did not vary signicantly
between the two groups (Table 2). Similarly, exercise
volume (i.e., total kilograms lifted in three sets of bench
press or back squat) did not differ signicantly.
Table 3 presents the daily energy intake and dietary
composition (mean intakes of protein, fat, carbohydrates,
and antioxidant vitamins in daily food rations of partici-
pants). No signicant difference was found between GTP
and PL groups for any of the variables studied. The diet in
both groups was adequate in terms of the dietary recom-
mendations for physically active men (Ziemlanski, 2001).
As shown in Table 4, the muscle-endurance test
performed by soccer players induced signicant changes
in measured parameters of blood acid-base equilibrium
(a drop in pH and increases in base deciency and anion
gap). These disturbances clearly pointed to metabolic
acidosis as a result of increased lactic acid production
during the exercise (postexercise lactate concentration
amounted to 14.70 ± 2.59 and 15.80 ± 1.44 mmol/L in
GTP and PL, respectively). However, a single dose of
green tea polyphenols ingested before the test did not
affect these changes.
490 Jówko et al.
As shown in Figure 3, acute GTP intake increased
preexercise plasma total catechin level (by 33% compared
with the corresponding value in the PL group; group main
effect, p < .05, and Group × Time interaction, p < .05). In
the PL group, no signicant changes in plasma catechins
were observed after the muscle-endurance test. However,
a signicant decrease in plasma catechins was observed in
the GTP group after 24 hr of recovery (decrease of about
22% compared with the preexercise value, p < .001, and
10%, compared with the postexercise value, p < .05; time
main effect, p < .05).
Changes in the markers of oxidative stress are pre-
sented in Table 5. The muscle-endurance test elevated
lipid peroxidation as indicated by signicant increases
in comparison with preexercise values in postexercise
plasma TBARS, which remained elevated 24 hr later
(time main effect, p < .001).
Similarly, plasma TAS and UA alterations (Table
5) were observed in response to the muscle-endurance
test (time main effect, p < .001). Both plasma TAS
and UA increased postexercise and remained elevated
compared with preexercise level until 24 hr after
the test.
No signicant changes in SOD activity in erythro-
cytes (Table 5) were observed in either group as a result
of the muscle-endurance test (time main effect, p > .05).
However, the PL group exhibited a tendency for a sig-
nicant increase in SOD activity at 5 min postexercise
(p = .0503) compared with resting activity.
Plasma CK activity did not change signicantly
immediately postexercise (Figure 4), but it increased
after 24 hr of recovery (time main effect, p < .001). In
the PL group, after the 24-hr recovery period CK activ-
ity was higher than preexercise and postexercise values,
whereas in the GTP group, CK activity was higher than
the preexercise value only.
Apart from increased preexercise plasma total
catechin level as a result of acute GTP ingestion, no
signicant effect of GTP intake on plasma TBARS,
TAS, and UA concentrations was found. Similarly, a
single dose of GTP did not affect SOD activity in eryth-
rocytes or plasma CK activity (p > .05 for group main
effect and Group × Time interaction in all mentioned
parameters).
Table 1 Characteristics of Soccer Players,
M ± SD
PL (
n
= 8) GTP (
n
= 8)
Age (years) 22.9 ± 5.5 22.4 ± 3.4
Height (cm) 180.9 ± 4.4 183.3 ± 5.6
Body mass (kg) 77.6 ± 3.6 78.7 ± 7.4
Body-mass index (kg/m2) 23.8 ± 1.7 23.4 ± 1.4
Years of training 9.3 ± 3.7 9.3 ± 1.9
Note. PL = placebo group; GTP = green tea polyphenol group.
Table 2 Results Obtained in the Muscle-
Endurance Test by Soccer Players, M ± SD
PL (
n
= 8) GTP (
n
= 8)
Total repetitions in
3 series
bench press 43.0 ± 9.9 50.7 ± 11.2
back squat 46.9 ± 6.1 53.7 ± 12.3
Total kilograms
lifted in 3 series
bench press 2,053.6 ± 410.9 2,427.1 ± 364.5
back squat 2,686.4 ± 476.7 3,047.1 ± 607.2
Note. PL = placebo group; GTP = green tea polyphenol group.
Table 3 Daily Nutritional Intake in PL and
GTP Groups, M ± SD
PL (
n
= 8) GTP (
n
= 8)
Energy (kcal) 3,611.4 ± 315.1 3,822.2 ± 304.3
Protein (g) 119.7 ± 13,9 122.9 ± 15.1
Carbohydrate (g) 492.1 ± 57.8 520.4 ± 36.7
Fat (g) 109.2 ± 31.1 116.7 ± 52.9
Vitamin C (mg) 71.6 ± 14.6 75.2 ± 17.0
Vitamin E (mg) 9.9 ± 1.9 11.3 ± 2.5
Vitamin A (RE) 1,264.9 ± 309.1 1,358.4 ± 372.6
Note. PL = placebo group; GTP = green tea polyphenol group; RE =
retinol equivalents.
Table 4 Changes in Blood pH, Base Deficiency, Anion Gap, and Lactate Concentration Induced
by a Muscle-Endurance Test Performed After Ingestion of Placebo or Green Tea Polyphenols in
Soccer Players, M ± SD
Placebo (
n
= 8) Green Tea Polyphenols (
n
= 8)
Parameter Preexercise Postexercise Preexercise Postexercise
Blood pH 7.40 ± 0.02 7.22 ± 0.04*** 7.39 ± 0.02 7.22 ± 0.05***
Base deciency (mmol/L) 0.56 ± 0.95 –14.44 ± 1.57*** 0.93 ± 1.63 –13.63 ± 3.37***
Anion gap (mmol/L) 15.04 ± 1.25 28.97 ± 0.97*** 14.57 ± 2.34 28.46 ± 2.48***
Lactate concentration (mmol/L) 1.51 ± 0.42 15.80 ± 1.44*** 1.42 ± 0.69 14.70 ± 2.59***
***Signicantly different (p < .001) from the preexercise value.
Green Tea Polyphenols and Exercise-Induced Oxidative Stress 491
Discussion
The objective of this study was to determine the effect of
acute ingestion of green tea polyphenols on blood mark-
ers of oxidative stress in soccer players subjected to an
intense muscle-endurance test.
Described disturbances of acid-base balance (Table
4) suggest that when the soccer players performed the
high-intensity muscle-endurance test it increased per-
oxidation of membrane lipids, as indicated by elevated
TBARS concentration in the plasma. This rise was
observed in both groups 5 min postexercise and main-
tained during the 24-hr recovery period. The TBARS
response observed in this study is in agreement with
previous investigations involving resistance exercise
(three sets of eight exercises at 10-RM) in a group of
recreationally weight-trained men (McBride, Kraemer,
Triplett-McBride, & Sebastianelli, 1998). In contrast,
while using an exercise protocol similar to that applied
in the study by McBride et al., Dixon et al. (2006) did
not observe any signicant changes in plasma level of
TBARS, both in resistance-trained and in untrained
men. Likewise, Bloomer et al. (2006) and Panza et al.
(2008) reported no increase in lipid-peroxidation mark-
ers after resistance-type exercise in trained men. The
discrepancy in lipid peroxidation between our results
and those reported earlier by McBride et al., as well as
other ndings (Bloomer et al., 2006; Dixon et al., 2006;
Figure 3 — Plasma total catechin concentration after ingestion of placebo (PL) or green tea polyphenols (GTP) in soccer players,
M ± SD. ***Signicantly different (p < .001) from the preexercise value. †Signicantly different (p < .05) from postexercise value.
#Signicantly different (p < .05) from the placebo group.
Table 5 Changes in Plasma Concentration of Thiobarbituric Acid Reactive Substances (TBARS),
Plasma Total Antioxidant Status (TAS), Uric Acid (UA), and the Activity of Superoxide Dismutase (SOD)
in Erythrocytes Induced by a Muscle-Endurance Test Performed After Ingestion of Placebo or Green Tea
Polyphenols in Soccer Players, M ± SD
Placebo (
n
= 8) Green Tea Polyphenols (
n
= 8)
Parameter Preexercise Postexercise 24-hr recovery Preexercise Postexercise 24-hr recovery
TBARS (μmol/L) 2.10 ± 0.95 4.15 ± 1.29*** 4.14 ± 1.36*** 2.00 ± 0.72 4.71 ± 0.94*** 3.65 ± 1.33**
TAS (mmol/L) 1.00 ± 0.08 1.28 ± 0.39** 1.26 ± 0.19* 1.06 ± 0.11 1.36 ± 0.10** 1.32 ± 0.08*
UA (mg/dl) 5.00 ± 1.36 6.23 ± 1.38** 6.26 ± 1.50** 5.04 ± 0.44 5.90 ± 0.97* 6.47 ± 0.81***
SOD (U/g Hb) 819.1 ± 177.0 1,014.2 ± 263.3 840.3 ± 212.4 955.9 ± 146.5 1,044.9 ± 228.9 1,036.4 ± 194.7
*p < .05, **p < .01, ***p < .001 (signicantly different from the preexercise value).
492 Jówko et al.
Panza et al., 2008), might be due to methodological dif-
ferences—the type of contraction performed, duration of
the protocol (Dixon et al., 2006), intensity and volume
of exercises (Bloomer et al., 2006), limited number of
muscle groups involved in the exercise (Bloomer et al.,
2006), and methodological limitations associated with
TBARS analysis (Dixon et al., 2006). However, we
used a modied TBARS assay for lipid peroxidation
(Jentzsch et al., 1996) recommended to minimize arti-
factual oxidative degeneration of lipids during the assay
and used recently by other workers (Bloomer, Cole, &
Fisher-Wellman, 2009).
The enhanced generation of ROS with acute physi-
cal exercise evokes changes in the body’s antioxidant
defense. There seems to be a general consensus in
the literature, supported by the ndings in the current
study, that plasma antioxidant levels increase after
exercise, although opposite results have been reported,
as well (Margonis et al., 2007; Skarpanska- Stejnborn,
Pilaczynska-Szczesniak, Basta, Deskur-Smielecka, &
Horoszkiewicz-Hassan, 2008). Mobilization of the tissue
nonenzymatic antioxidant stores into the plasma is a
widely accepted phenomenon that helps maintain the
antioxidant status of plasma when needed (Margonis et
al., 2007). In our study, TAS plasma level increased after
the muscle-endurance test and was maintained during the
recovery period. Likewise, the concentration of TBARS
in plasma after 24 hr of recovery was still higher than the
preexercise values. This suggests an enhanced generation
of free oxygen radicals as a result of the test performed by
the athletes, overwhelming their capacity to detoxify ROS
and thus producing oxidative stress. A similar tendency of
changes in blood levels of TAS and malondialdehyde was
demonstrated by Shing et al. (2007) after high-intensity
interval cycling in highly trained cyclists.
UA, a primary end product of purine metabolism, is
the principal water-soluble antioxidant present in blood
(Rabovsky, Cuomo, & Eich, 2006). It is well known that
elevated plasma UA concentration is responsible for one
third of the plasma TAS increase after strenuous exercise
(Child, Wilkinson, Falloweld, & Donnelly, 1998). This
was conrmed by our study, as the muscle-endurance test
affected plasma UA concentrations in the same pattern
as plasma TAS levels.
It has been previously demonstrated that ROS
generation could induce changes in the activity of anti-
oxidant enzymes in the red blood cells (Fisher-Wellman
& Bloomer, 2009). Reports of alterations in erythrocyte
SOD activity after exercise are equivocal. Decreases in
erythrocyte SOD activity after extreme running competi-
tion in well-trained athletes were observed by Machefer
et al. (2004). In turn, other works report increased SOD
activity in the red blood cells after a half-marathon (Mar-
zatico, Pansarasa, Bertorelli, Somenzini, & Della Halle,
1997) and rowing incremental test (Skarpanska- Stejn-
born et al., 2008) or a lack of changes after incremental
exercise (Vider et al., 2001) or sprint-running exercise
(Marzatico et al., 1997). In the current study, SOD activ-
ity in erythrocytes did not change signicantly after the
muscle-endurance test. However, in the PL group, a
tendency for increased SOD activity was seen at 5 min
postexercise (p = .0503), indicating an enhanced generation
Figure 4 — Changes in plasma creatine kinase (CK) activity induced by muscle-endurance test performed after ingestion of pla-
cebo (PL) or green tea polyphenols (GTP) in soccer players, M ± SD. *Signicantly different (p < .05) from the preexercise value.
†Signicantly different (p < .05) from the postexercise value.
Green Tea Polyphenols and Exercise-Induced Oxidative Stress 493
of superoxide anion associated with the intense muscle-
endurance test.
There is evidence that under conditions of exercise-
induced oxidative stress, enhanced peroxidation of
membrane lipids is one of the factors leading to changes
in the integrity of the cellular membrane (Marzatico et
al., 1997). This results in an increase in the postexercise
activity of CK in plasma (Branciaccio, Maffulli, &
Limongelli, 2007). Free radicals’ substantial contribution
to muscle-tissue damage linked with acute exercise is
indicated by a positive correlation between postexercise
activity of CK and concentration of TBARS in blood
plasma that has been reported by numerous investiga-
tions (Urso & Clarkson, 2003). In the current study, the
signicant increase in plasma CK activity noted 24 hr
after the muscle-endurance test in both groups indicates
that the exercise-induced oxidative stress disrupted the
integrity of muscle-cell membranes. These results are
consistent with those of other authors (Dixon et al., 2006;
McBride et al., 1998).
Dietary antioxidants are claimed to play a major
role in the protection of cells from oxidative damage
by improving the body’s defense systems’ handling of
free-radical attack and by helping to reduce postexercise
elevations in plasma CK activity (Bloomer, Goldfarb,
McKenzie, You, & Nguyen, 2004). Green tea is a rich
sources of catechins—compounds that belong to the
polyphenol group. The antioxidative properties of green
tea polyphenols were observed in both in vitro (Raza &
John, 2007) and in vivo studies (Alessio et al., 2002).
In our study, acute ingestion of GTP resulted in a slight
but signicant increase in total catechin concentration
in plasma. Taking into account the results of other stud-
ies (Lee et al., 2002; Renouf et al., 2010), the time span
used in the current study between the administration of
GTP and the preexercise blood-sample collection (1.5
hr) should be sufcient for blood catechins to reach peak
concentration. Chow et al. (2005) showed that taking
polyphenon E with a meal reduced oral bioavailability
of green tea catechins and considerably extended the
time required to reach the peak concentration of plasma
catechins in comparison with taking polyphenon E on an
empty stomach as in an overnight fast. In our study, GTP
capsules were administered 2 hr after a light breakfast,
so the meal was presumed not to affect catechin absorp-
tion in the small intestine. In our work, however, total
plasma catechin concentration after ingestion of GTP
was consistent with Chow et al.’s observations in a fed
condition, but not in a fasting condition. It can therefore
not be excluded that, in our study, the meal could have
affected the oral bioavailability of GTP and that a period
longer than 1.5 hr would be needed to reach the peak
concentration of plasma catechins.
In the current study, despite an increase in total
plasma catechins, no changes in TAS plasma level after
acute ingestion of GTP were observed. This may explain
why GTP ingestion did not affect any other parameters of
oxidative stress. It is well known that, due their low bio-
availability, the contribution of polyphenolic compounds
to the antioxidative capacity of blood plasma is restricted
(Morillas-Ruiz et al., 2006). For this reason, the dose of
green tea polyphenols administered in our study might
have been insufcient to modify the whole antioxidant
plasmatic state. In the study of Henning et al. (2005), a
single intake of polyphenon E containing twice the dose
of polyphenols as in our study was insufcient to achieve
an increase in plasma antioxidant capacity determined
using Trolox equivalents. On the other hand, in another
study (Rabovsky et al., 2006), a single administration (to
fasted subjects) of a green tea extract in a dose of 600
mg was demonstrated to increase plasma antioxidant
capacity, measured as FRAP after enzymatic removal of
UA. In our study, acute ingestion of GTP was observed
to have no effect on plasma TAS, even when plasma TAS
levels were corrected for plasma UA (data not shown).
Therefore, it is likely that there is no acute effect of GPT
ingestion, and a longer period of GTP supplementation
(i.e., 1–7 weeks) is necessary to induce protection against
exercise-induced oxidative stress, as revealed by previous
studies (Alessio et al., 2002; Panza et al., 2008) and our
latest study (Jówko et al., 2011).
It must be emphasized that in the current study the
results obtained in the muscle-endurance test (i.e., the
number of repetitions and total weight lifted in both exer-
cises) were higher (although this rise was not signicant)
in the GTP group than in the PL group. Thus, the actual
differences between groups, although not statistically
signicant, may reach physiological signicance, which
could mask potential effects of GTP ingestion on the
parameters of oxidative stress. However, the results of
another study (Viitala, Newhouse, LaVoie, & Gottard,
2004), in which the effect of vitamin E supplementa-
tion on resistance-exercise-induced lipid peroxidation
was evaluated in trained and untrained subjects, do not
conrm the mentioned hypothesis. In Viitala et al.’s
study, a similar magnitude of oxidative stress (plasma
malondialdehyde concentration) was observed in all
investigated groups (i.e., trained supplemented, trained
placebo, untrained supplemented, and untrained placebo),
despite signicantly higher plasma vitamin E concentra-
tion in supplemented than the unsupplemented groups, as
well as signicantly greater work output in trained than
untrained participants (Viitala et al., 2004).
On the other hand, it cannot be excluded that, in
our study, the differences in the number of repetitions
and total weight lifted between groups resulted solely
from acute GTP ingestion. Consequently, the higher
volume of work done in the GTP group (though it was
not signicant), accompanied by postexercise changes
in the parameters of acid-base equilibrium and indices
of oxidative stress similar to those of the PL group, may
have resulted from acute GTP ingestion.
In conclusion, the intense muscle-endurance test
employed in the current study was observed to induce
oxidative stress and muscle damage in soccer players. A
single dose of green tea polyphenols administered before
the test failed to suppress the exercise-induced oxidative
stress. Presumably, a higher dose of polyphenols may
494 Jówko et al.
be required to exert a positive effect on oxidative-stress
parameters; this needs to be conrmed by further studies
with higher numbers of athletes per group.
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