Blood serum DSC analysis of well-trained men response to CrossFit training and green tea extract supplementation
Blood serum DSC analysis of well-trained men response to CrossFit training and green tea extract supplementation
Anna Michnik 0 1 2 3
Ewa Sadowska-Kre?pa 0 1 2 3
Przemys?aw Domaszewski 0 1 2 3
Klaudia Duch 0 1 2 3
Ilona Pokora 0 1 2 3
0 The Silesian Centre for Education and Interdisciplinary Research , ul. 75 Pu?ku Piechoty 1A, 41-500 Chorzo ?w , Poland
1 Department of Medical Physics, A. Che?kowski Institute of Physics, University of Silesia , ul. Uniwersytecka 4, 40-007 Katowice , Poland
2 Division of Tourism and Recreation, Faculty of Physical Education and Physiotherapy, Opole University of Technology , Opole , Poland
3 Department of Physiological and Medical Sciences, The Jerzy Kukuczka Academy of Physical Education in Katowice , ul. Miko?owska 72a, 40-065 Katowice , Poland
Differential scanning calorimetry (DSC) has been used for the detection of post-exercise changes in blood serum resulting from participation in the CrossFit (CF) training combined with green tea extract (GTE) supplementation. Blood samples from 20 well-trained men were collected at rest, immediately post-exercise and after 1 h of recovery in two trials: first before and second after CF training combined with GTE or placebo administration in the supplemented (S) and control (C) groups, respectively. Selected muscle damage biomarkers have been compared in different phases of the experiment. A significant increase in blood lactate content has been observed post-exercise in both trials in both participants' groups. The opposite trends have been noted for the C and S groups in creatine kinase (CK) activity changes recorded during the first to the second trial: an increase in CK for the control and a decrease for the supplemented group in all phases of the experiment: pre-exercise, post-exercise and after recovery. In the second trial, all CK values for the S group have been found significantly lower than the corresponding values recorded in the C group. These results suggest a
CrossFit training extract; Human blood serum
mitigate effect of GTE supplementation on post-training
muscle damage. DSC results did not reveal clear effects of
training nor GTE supplementation on serum denaturation
transition. However, interesting dependences of
thermodynamic parameters describing this transition have been
observed in different phases of the experiment. Statistically
significant negative correlations have been found between
post-training VO2max and post-exercise thermodynamic
parameters associated with haptoglobin contribution to
serum denaturation transition.
The consumption of exogenous supplemental antioxidants
among athletes has increased despite the lack of clear
evidence of their benefits. The majority of published papers
confirm the general belief that antioxidant supplements
improve health and even prevent several diseases.
However, there is also a growing evidence regarding the useless
or negative effects of antioxidant supplementation on
physiological and biochemical outcomes and performance
of exercise-trained individuals [1?4].
After many years of intensive research, it is now well
documented that exhaustive exercise induces production of
reactive oxygen species (ROS) resulting in increased
oxidative stress, which may lead to the damage of cellular
components, including proteins, lipids, carbohydrates and
nucleic acids. So, a great body of researchers have
investigated the possibility to prevent the exercise-induced
oxidative stress and muscle damage through nutritional
intervention, mainly using antioxidants. For a
comprehensive review and discussion on this topic, please refer, e.g.,
to [4?6]. On the other hand, recent investigations report
also several positive aspects of ROS generation in sport
performance and their role in cell signaling and adaptation
to regular training [7?9]. ROS play an important role in
lipid peroxidation which leads to an increase in
permeability of cell skeletal membranes, followed by a release of
cytosolic proteins and enzymes such as creatine kinase
(CK) and lactate dehydrogenase (LDH) into the blood .
Moreover, if oxidative stress levels are already low, which
may be the case in healthy young individuals and athletes,
the exogenous antioxidant supplementation may be
detrimental. Thus, the relationship between exercise, oxidative
stress and supplementation remains a complex issue.
Tea is a rich natural source of flavonoid antioxidants
from the polyphenol family. Particularly, green tea extracts
with antioxidant, anti-carcinogen, anti-inflammatory and
anti-radiation properties have been a focus of recent
scientific research. Beneficial effects of green tea or its
extracts against cancer, obesity, metabolic syndrome and
cardiovascular disease have been reported [11?13].
Antioxidant properties of green tea are associated with the
presence of several polyphenols, primarily catechins
including epigallocatechin gallate (EGCG), (-)
epicatechin gallate (ECG), (-) epicatechin (EC) and (-)
epigallocatechin (EGC) . Zhang et al.  have recently
shown that long-term supplementation with green tea
polyphenol could provide an efficient protection against the
health issues induced by high-voltage power lines. They
found that 12 months of green tea polyphenol
supplementation (GTPS) significantly diminished the negative
effects of extremely low-frequency electromagnetic fields
(ELF-EMFs) on the health of the exposed workers.
However, 3 months after GTPS withdrawal, no protective
effects of previous supplementation on oxidative stress and
oxidative damage to DNA were observed.
Studies examining the effects of green tea consumption
on exercise-induced oxidative stress and exercise
metabolism in humans are rather scarce and results of these studies
are often inconclusive [16, 20]. Previous studies have
generally found that antioxidant supplements do not
improve performance; however, there are many reports that
exogenous antioxidant supplements may strengthen
antioxidant defense system in healthy exercising humans
and limit or even prevent the exercise-induced tissue
damage or help the sportsmen to recover from the damage
[21?23]. Richards et al.  have reported an increase in
sport performance after green tea catechins (GTC)
ingestion, namely a short-term ingestion of EGCG caused
VO2max increase in 14 out of 19 subjects. Jo?wko et al.  have
reported that a long-term (4-week) green tea extract (GTE)
supplementation enhanced plasma total polyphenols at rest
as well as 5 min after the muscular endurance test and it
contributed to the rise of resting total antioxidant status in
plasma of previously untrained men. They concluded that
dietary supplementation with GTE may provide protection
against oxidative damage induced by both short-term
muscular endurance test and long-term strength training. In
another Jo?wko et al.?s study , green tea
catechins-treated soccer players were able to perform a higher number of
lift repetitions during the muscle endurance test, but none of
the analyzed plasma biomarkers was affected by the
ingestion of green tea catechins, suggesting that a 640 mg
dose was too low to attenuate exercise-induced oxidative
stress and muscle damage. Hodgson et al.  found that in
healthy physically active men, GTE enhanced lipolysis and
fat oxidation when compared to placebo, but only under
resting conditions, whereas no effect of GTE was seen
during exercise. In a more recent study, Sugita et al. 
have investigated the effects of green tea catechins on
oxidative stress metabolites in healthy individuals both at
rest and during exercise. The overall data presented in this
study suggested that GTC (a single dose of 780 mg) could
improve physical performance particularly in terms of
endurance capacity expressed as VO2max in a physically
active general population.
Differential scanning calorimetry (DSC) has recently
been found useful in the support of various medical
diagnoses [25?36] by analysis of plasma or serum heat capacity
changes in the temperature range of protein components
thermal denaturation. DSC profiles of biofluids are able to
reflect their modified composition, changes in thermal
stability of major proteome components resulting from
covalent modifications or binding interactions involving
disease biomarkers. Generally, DSC profile of
serum/plasma heat capacity changes provides information on
the health status of blood donor based on the individual
thermal characteristics. Thus, it seems justified to use the
calorimetric analyses also for the evaluation of the
beneficial or detrimental effects of physical activity or
supplementation. Such innovative attempts of DSC adoption for
the resolving of some problems in sport medicine were
made by us recently [37, 38].
The purpose of the current study was to evaluate the
effects of green tea extract supplementation in combination
with CrossFit training lasting for 6 weeks on the physical
performance and recovery after a short-term exercise in
well-trained men. In addition to the typical evaluation of
blood biomarkers of muscle damage, such as the activity of
lactate dehydrogenase (LDH) and creatine kinase (CK),
nonconventional approach has been applied. Using DSC
method, blood serum samples taken from the participants
during two trials: before and after a 6-week CrossFit
training before, immediately after and 1 h after the exercise
test have been analyzed.
Participants of the experiment
Twenty nonsmoking male students of the Opole University of
Technology, volunteers involved in CrossFit training (CF
training), were randomized between the following groups: the
control group-receiving placebo (C) and the group
supplemented with the green tea extract (S). All subjects were
informed about the purpose and the nature of the research
before giving their written consent to participate in the
experiment, which had been approved by the Ethics Committee of the
Jerzy Kukuczka Academy of Physical Education in Katowice
(No. 4/2013). The exclusion criteria were the use of tobacco
products, alcohol consumption, the use of any medicine or
dietary supplements during 4 weeks prior to the study.
All supplements were administrated in soft gelatinous
capsules (Olimp Labs, De?bica, Poland) at a dose of two
capsules once a day for 6 weeks. One placebo capsule
contained microcrystalline cellulose, magnesium stearate
and maltodextrin instead of plant extract. One GTE capsule
contained 250 mg of standardized GTE (245 polyphenols
including 200 mg catechins among 137 mg
epigallocatechin-3-gallate) and additional substances such as
maltodextrin, microcrystalline cellulose and magnesium
stearate. The daily doses of GTE extract were treated
according to the manufacturer?s instructions. In case of
adverse events associated with dietary supplements, all
subjects could opt out of taking part in this study.
All students participated an incremental maximal oxygen
uptake (VO2max) test on cycle ergometer (Sport Excalibur) at
two occasions, i.e., before the CF training and
supplementation (first trial) and then once more after 6 weeks of CF
training and supplementation (second trial). After a short
warm-up cycling, the subjects cycled in 3-min phases
starting at a power output of 40 W, and increasing progressively
by 40 W. The exercise was continued until exhaustion.
Blood serum samples
Blood samples were drawn from antecubital vein either
into test tubes anticoagulated with heparin or containing
clot activator for collection, respectively, of plasma or
serum samples at rest, 3 min after exercise and after 1 h of
passive recovery. Fresh plasma samples were assayed for
activities of creatine kinase (CK), lactate dehydrogenase
(LDH) and concentrations of lactate (LA) using diagnostic
kits from Randox Laboratories (CK522, LD3818 and
Serum samples were stored at -20 C before analysis.
For DSC experiment, serum samples were diluted 20-fold
with distilled degassed water. The pH value of the diluted
samples has been within the range 6.5?7.0.
DSC measurements were taken on the VP DSC MicroCal
instrument (Northampton, MA) in the temperature range
20?100 C with the heating rate 1 C min-1. A constant
pressure of about 1.8 atm was exerted on the liquids in the
cells. The calorimetric data were corrected for the
instrumental baseline water?water. DSC curves were normalized
for the gram mass of protein and next a linear baseline was
subtracted. An apparent excess specific heat capacity Cpex
(J C-1 g-1) versus temperature ( C) has been plotted.
The following parameters of observed DSC transitions
have been determined: temperatures of local peak maxima
Tm (m = 1, 2, 3), excess specific heat capacities at these
temperatures Cpm, the enthalpy (DH) of serum
denaturation (calculated as the area under the endothermic peak,
expressed in J g-1) and the width of peak in its half height
(HHW). All other experimental conditions and DSC data
analysis were practically the same as during the earlier
DSC study of human blood serum and described in .
Statistical analysis was performed using the Statistica 12
software. For all measures, descriptive statistics were
calculated. Analysis of variance (ANOVA) with the stage of
experiment as a repeated measure and the group as
categorical variable was used. Mauchly?s test for sphericity
was included as a part of the procedure. If repeated
measures ANOVA was statistically significant, Tukey?s post
hoc test was applied. Student?s t test was used to compare
the mean values between the two independent groups. The
accepted level of significance was taken as p \ 0.05.
When the results of Shapiro?Wilk test revealed that the
distributions of the studied variables differed from normal
data or in the case of nonhomogenous variances of
analyzed groups (in Leven?s test p \ 0.05), appropriate
nonparametric tests were used for comparative analyses.
Pearson?s correlation coefficients were found to describe
the relationships between biochemical and thermodynamic
blood serum parameters.
Results and discussion
In Table 1, basic characteristics of two groups of
participants of the study are given. No significant differences
were found between the C and S groups in regard to age,
Table 1 Characteristics of participants
C group (n = 9)
S group (n = 11)
Values are means ? sd
* The mean value of differences between VO2max after and before CF training
height and body mass, as well as in VO2max values before
the training. The placebo group has demonstrated
something greater improvements in respiratory function with
training (dVO2max = 1.9 ? 2.7) compared with
GTE-supplemented group (dVO2max = 1.7 ? 4.6), but the
difference was within the experimental error.
Blood biomarkers presented in Table 2 indicate that
before the CF training, the mean values of LA
concentration and CK activity were similar in both groups, while the
level of LDH activity was significantly higher (p = 0.01 in
Student?s t test) in the group assigned to supplementation.
It is probably a random difference and its reason is
unknown especially that both the resting and post-exercise
activities of LDH were within the references ranges, i.e.,
230?460 U L-1. After the training LDH activity remained
unchanged in GTE-supplemented group and slightly
increased in placebo group. LA level significantly
increased after the exercise in both trials for both groups.
The highest CK activity occurred for the C group after the
exercise performed in the second trial. Differences between
this CK value and all values (pre-exercise, post-exercise
and after the recovery) in the first trial for the C group have
been found statistically significant. Generally, a slightly
higher post-exercise CK values were observed compared to
other phases of the experiment (see Table 2). However, big
standard deviations due to high individual variability
diminish the perceived tendency. It seems important that
the opposite trends have appeared for the placebo and
GTE-supplemented groups in all CK activity changes from
the first to the second trial: an increase for the first and a
decrease for the second of said groups. Statistical analysis
has revealed significant differences between C and S
groups in post-training CK activities for all stages of
experiment (p = 0.03, p = 0.008 and p = 0.02 for
preexercise, post-exercise and after the recovery differences,
respectively). For GTE-supplemented group, post-exercise
CK activity before the training has been found significantly
higher than post-training pre-exercise and after 1 h of rest
values. These results suggest that supplementation of tea
polyphenols, at doses recommended according to
manufacturer?s instructions, may diminish post-training skeletal
muscle damage through suppressive action on oxidative
stress and inflammation .
Averaged serum DSC curves for C and S groups of men
are shown in Fig. 1. Both curves are very similar and
differences between them are within the experimental error,
besides the temperature range above 80 C. The complex
endothermic transition observed for serum solution
represents the denaturation of serum proteins, which proceeds
over the approximate temperature range 40?90 C. Most
commonly three local maxima can be noticed at T1, T2 and
T3. However, sometimes, T1 or T2 is absent. For this reason,
the first maximum and the second maximum are not well
visible in the averaged curves presented in Fig. 1. An
contribution connected with protein aggregation is
noticeable, particularly in the higher temperature range. The
thermal profiles of heat capacity changes for aqueous
solutions of human blood serum from athletes have been
described and discussed in details earlier . Comparing
DSC curves of athletes serum diluted with distilled water
(pH 6.5?7.0) with curves reported for serum/plasma of
healthy persons where the final pH of solutions was in the
range 7.2?7.5 [25?27, 29?36], distinct differences are
visible. The main origin of these differences is probably the
thermal denaturation profile of fatty acid-free fraction of
albumin. DSC transition representing unfolding of this
protein was shown much sharper in buffer (pH 7.2) than in
water (pH 6.5) solution (see Fig. 1a in ).
The averaged effects of CF training in the C group and
training plus supplementation in the S group on DSC serum
profiles in pre-exercise stages are presented in Fig. 2a, b,
respectively. In both cases, the differences between DSC
curves corresponding to serum before and after the training
are very small, and the bigger one seems to be that for the
Table 2 Changes in LA concentration, CK and LDH activities induced by the CF training with concomitant supplementation with placebo
(n = 9) or GTE (n = 11)
Values are means ? s.d., be before the exercise, ae 3 min after the exercise, r1h after 1 h of passive recovery
Fig. 1 Mean serum DSC curves for participants from C (solid lines)
(n = 9) and S (dotted lines) (n = 11) groups; the shadow represents
control placebo group C. These small averaged
posttraining changes appear in the region of T1 for the C group
and around T2 for the S group.
Although mean DSC curves have been practically
unchanged through the CF training and GTE
supplementation, in individual cases, significant differences in heat
capacity thermal profile of participants serum could be
observed. Examples of such meaningful differences are
shown in Fig. 3a, b for selected participants from C and S
groups, respectively. A decrease in Cp2 (the heat capacity
corresponding to local maximum at T2) intensity is well
visible in Fig. 3a for the representative from placebo group
and a substantial changes in the temperature range
55?65 C in Fig. 3b, which have appeared after the
training combined with supplementation.
To illustrate and to evaluate the effect of a graded
exercise to volitional fatigue and next the 1 h of rest, sets
of three curves are shown in Fig. 4 for the C group before
the training and in Fig. 5 for the S groups after the training
Fig. 2 a Comparison of mean serum DSC curves in pre-exercise
stage before (solid lines) and after (dotted lines) the CrossFit training
for the C group. b Comparison of mean serum DSC curves in
preexercise stage before (solid lines) and after (dotted lines) the CrossFit
training for the S group
and GTE supplementation. The comparison of these
average curves indicates that the exercise performed by men
slightly shifts the observed endothermic transition to lower
temperatures. The effect visible in Fig. 4 has been
Fig. 3 a An example of substantial differences between serum DSC
curves before (solid lines) and after (dotted lines) CF training for the
representative from the C group. b An example of substantial
differences between serum DSC curves before (solid lines) and after
(dotted lines) CF training in combination with GTE supplementation
observed even weaker in the case of S group (not shown)
and after the training in both groups. After the recovery
period of 1 h changes recede, but for the S group in the
second trial mean DSC curve for serum acquired after the
rest does not practically differ from that corresponding to
Fig. 4 Comparison of mean serum DSC curves in three stages:
preexercise (solid lines), post-exercise (dotted lines) and after 1 h of rest
(dashed dotted lines) before the CrossFit training for the C group
Fig. 5 Comparison of mean serum DSC curves in three stages:
preexercise (solid lines), post-exercise (dotted lines) and after 1 h of rest
(dashed dotted lines) after the CrossFit training for the S group
post-exercise serum (Fig. 5). It is worth mentioning that
the response to exercise and rest varied substantially
among individual participants of the study.
Modifications of serum DSC transition observed in
current study due to the exercise and rest for well-trained
participants are very small in contrast to relatively distinct
changes found in our previous study for amateur cyclists
. The main reason for this poor response of serum
proteins on strenuous exercise is probably a high physical
performance of participants even before the training.
CrossFit is extremely popular form of multimodal exercise
training conducted at high intensity in order to improve
endurance, strength and flexibility . Data from
available studies suggest that catechins can improve physical
performance particularly in terms of endurance capacity
and VO2max in untrained subjects, but the same results
cannot be reached in physically active people and
welltrained athletes .
The mean values ? SEM of parameters describing the
endothermic denaturation transition for serum acquired
from participants in the first (before the CrossFit training)
and in the second (after the training, marked with
additional letter t) trial for C (control?placebo) and S (GTE
supplemented) groups are presented in Figs. 6?9. The
dependence of these parameters on the stage of experiment:
before exercise (be), after exercise (ae) and after 1 h of rest
(r1h), is illustrated.
Figure 6 suggests that the character of T1, T2 and T3
dependences on the stage of experiment is very similar
irrespective of the group and a completion of the training.
No significant differences in Tm values have been observed
between both groups in the adequate study periods. For
both groups in both trials, post-exercise T1 was somewhat
lower, while post-exercise T2 and T3 were higher than
before the exercise. Taking together results for both groups
in both trials, the repeated measure ANOVA indicated
statistically significant differences between T2
(p = 0.00005) as well as between T3 (p = 0.00004) in
different stages of experiment. According to post hoc
Tukey?s test, post-exercise values of T2 and T3 were
significantly higher than after 1 h of rest. Considering
additionally the factor ??group,?? mentioned differences for T2
were significant only in GTE-supplemented group.
Moreover, post-exercise values of T3 in both trials were
significantly higher than before-exercise value in the second
trial. Only for the S group post-exercise T3 value in the first
trial was significantly higher than values of T3 obtained in
both trials after the rest.
Changes in Cp1, Cp2 and Cp3 related to the stage of
experiment, shown in Fig. 7, seem somewhat different for
the C and S groups. However, suggested by Fig. 7
differences between both groups in Cpm mean values are not
statistically significant. Interesting results have been found
for Cp2 parameter. For the S group, after the training and
supplementation Cp2 value is maintained at a constant,
higher than in the first trial, level. Generally, taking the
stage of experiment as a main factor, according to the
repeated measure ANOVA, differences between mean Cp2
values are statistically significant (p = 0.047). Taking into
consideration the data obtained for both groups, the
preexercise Cp2 in the first trial has been found significantly
lower than post-exercise value after the training (p = 0.02
in post hoc Tukey?s test).
The main origin of the local maximum (T2, Cp2) in the
serum denaturation peak is probably haptoglobin, the
protein from alpha-2 globulins fraction [25, 37].
Haptoglobin is an acute-phase protein, the synthesis of which is
increased during inflammation. Haptoglobin binds free
hemoglobin released from erythrocytes with high affinity
and therefore inhibits its oxidative activity. In this study,
significant negative correlations have been found between
VO2max after CF training and post-exercise T2 (r = -0.52;
p = 0.03) as well as post-exercise Cp2 (r = -0.68;
p = 0.03) after the training. The first of said correlations
was even higher in the control group (r = -0.78), while
the second in the supplemented group (r = -0.86). Thus,
higher VO2max after the CF training implies a smaller
increase in T2 and Cp2 after the exercise.
The relationship between VO2max and Cp2 intensity
confirms the observation that a lack of T2 local maximum
has been most frequently accompanied by VO2max higher
than 50 mL min-1 kg-1. Moreover, the case shown in
Fig. 3a represents a man with the lowest value of VO2max:
39 and 43 mL min-1 kg-1 before and after the CF
training, respectively. Among all DSC curves recorded in the
current study, it was the case with the highest Cp2
component. In accordance with the found negative correlation
between VO2max and Cp2, a decrease in Cp2 component has
been observed due to the increase in VO2max after the
Figures 8 and 9 indicate that trends of changes in the
enthalpy of serum denaturation (DH) and HHW are very
similar in both groups, but these values are bigger for the S
group. An increase in DH and HHW after the exercise and
a decrease after the recovery period have been observed in
the first as well as in second trial for both groups.
Statistically significant differences have been found only for
HHW parameter due to ??group?? and ??stage?? factors
Fig. 8 Mean values of DH (?s.e.) for different stages of experiment
in both groups
Fig. 9 Mean values of HHW (?s.e.) for different stages of
experiment in both groups
(p = 0.004 and p = 0.01, respectively). Additionally, post
hoc Tukey?s test has revealed significantly broader serum
denaturation transition in the post-exercise stage in the
second trial for the S group than in all stages for the C
group except these after the exercise.
An explanation of why obtained HHW values are higher
for the S than for the C group and after the exercise is not
simple, and we are not able to clarify this problem at
present. Generally, smaller HHW indicates greater
cooperativity of the observed thermal transition, but exothermic
proteins aggregation following their endothermic unfolding
may also cause a narrowing of the denaturation transition.
Another reason of differences in the width of peak
represented serum denaturation may be the proportion of
constituent proteins or modification of their structures, for
example, due to oxidation. Slightly higher values of Cp3
for the C than for the S group (except the after recovery
stage in the second trial) suggest a higher contribution from
gamma globulins in the control group. However, more
prominent cause of considered broadening of serum
transition seems to be connected with its low temperature range
(see Figs. 1, 4), where the main contribution comes from
albumin, the most abundant human serum protein. An
increase in albumin level after the exercise was found in
our earlier study . Additionally, conformational
changes in albumin molecule due to the binding of fatty acids or
other ligands as well as protein glycation affect its folding
and stability [41, 42]. This heterogeneity of the albumin
molecule may cause the extension of thermal unfolding
range. Albumin plays, among others, key antioxidant
functions. In normal conditions, oxidation of albumin
involves only a minor part of the protein. However, due to
oxidative stress more oxidants react with albumin and give
rise to oxidized albumin level. Reported by Musante et al.
, value of DH for oxidized albumin was bigger and
thermal melting peak was shifted significantly to the higher
temperature range (Tm above 80 C was observed) in
comparison with normal albumin. The oxidative stress
caused by strenuous physical exercise may lead to the
increased fraction of oxidized albumin in serum . This
may be one of the reasons for broadening the temperature
range of serum denaturation because of the additional
contribution from this form of albumin also to the higher
temperature side of serum endothermic transition.
It is now generally accepted that strenuous physical
exercise can induce oxidative stress in humans. Antioxidants
supplementation may support endogenous defense system
and prevent or reduce oxidative stress, decrease muscle
damage and improve exercise performance. The results of
the present study support this view to a certain extent.
According to the obtained data, GTE supplementation
parallel with a strenuous CF training prevents the
posttraining increase in creatine kinase (CK) activity observed
for the placebo group. Thus, GTE can mitigate the muscle
damage induced by physical exercise.
DSC results do not indicate the clear effects of training
or GTE supplementation on serum denaturation transition.
However, thermodynamic parameters of this thermal
transition change in a characteristic way during the
performed experiment. While comparing these parameters for
the C and S groups in two trials: before and after the CF
training and in three phases: pre-exercise, post-exercise and
after 1 h of resting recovery, some significant differences
have been found. In particular, in both trials, taken together
for both groups post-exercise values of T2 as well as T3
have appeared significantly higher than corresponding
values after the recovery. The post-exercise values of T3 in
both trials have also been stated as significantly higher than
before-exercise T3 value in the second trial. No significant
differences in Tm values have been observed between both
groups in corresponding study periods. Taking into account
the data obtained for both groups, the pre-exercise Cp2
before the training has been shown significantly lower than
post-exercise Cp2 after the training. Comparing the width
of the serum denaturation transition, it has been higher for
the S than for the C group in all stages of the experiment.
The broadest transition (the highest mean HHW value) has
been observed after the exercise in the second trial for the S
group. It is not clear why the exercise in conjunction with
CF training and GTE supplementation leads to a reduction
in the transition cooperativity.
A summary of the biochemical and calorimetric data has
revealed the relationship between VO2max and Cp2
intensity. The findings of statistical analysis indicate significant
negative correlation between these variables. The overall
data presented in this study suggest that in terms of VO2max
catechins do not improve physical performance in
physically active, well-trained men. However, further studies are
needed to clarify this problem.
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