The redox state represents the oxidation/reduction potential within the cell and plays an important role in cells function [
It has been known that exercise of sufficient volume, intensity, and duration can induce oxidative stress [
Here, it is assumed that individual’s state of training could be important to determine the extent of redox homeostasis following acute bout of exercise [
Thirty voluntary well-trained (
Subjects’ characteristics of WT, MT, and UT groups.
Characteristics | WT group | MT group | UT group |
|
|
---|---|---|---|---|---|
Age (yr) | 21.10 ± 1.72 | 21.70 ± 1.88 | 20.10 ± 1.44 | 2.264 | 0.123 |
Weight (kg) | 69.00 ± 6.94 | 69.40 ± 9.81 | 73.20 ± 9.47 | 0.688 | 0.511 |
Height (cm) | 176.00 ± 7.87 | 173.20 ± 5.78 | 176.90 ± 4.28 | 0.981 | 0.388 |
BMI (kg/m2) | 22.28 ± 1.87 | 23.12 ± 3.01 | 23.37 ± 2.74 | 0.485 | 0.621 |
Vo2max (mL/kg/min) | 60.90 ± 3.96 | 52.76 ± 2.62 | 43.63 ± 4.11 | 56.538 | <0.001 |
Body fat % | 9.15 ± 0.96 | 11.68 ± 1.74 | 15.98 ± 4.17 | 16.669 | <0.001 |
Years of training (yrs) | ≈10.00 | ≈10.00 | 0 | — | — |
Training (h⋅week−1) | 6.4 ± .33 | 1.20 ± 0.16 | 0 | — | — |
Data are mean ± SD.
At the beginning of the experiment, the study protocol was approved by the Ethical Committee of Ardebil University, and then participants completed medical history questionnaire and signed informed consent. None of the participants showed signs of bacterial or viral infection symptoms. In addition, other exclusion criteria were drinking alcohol, smoking, and taking anti-inflammatory drugs or antioxidant supplements.
Generally, this study was designed in two parts: the preliminary and main exercise trials.
Two weeks prior to enrollment into the study, all subjects passed a physical examination and a maximal oxygen consumption (Vo2max) test.
The subjects’ weight and height were recorded using electronic scale (model 712; Seca, Germany) and portable Stadiometer (Holtain, UK), respectively, and then participants completed a body composition assessment.
All subjects performed an incremental test on a treadmill (Model 6150E, Sport Art, UK) using Bruce test [
All subjects kept their normal diet during the study period and completed daily food records until the day of experiment. Diet records were analyzed for total kilocalories, protein, carbohydrate, fat, vitamin C, vitamin E, vitamin A, antioxidants sources, and selenium intake using commercial software (Food Processor IV; Nutrition System, Iran).
Subjects completed exercise protocol including 5 min running with 50% Vo2max and 30 min running with 75% Vo2max on treadmill, while heart rate was continuously monitored using short-range telemetry (Polar S610, Polar Electro, Finland). Water consumption was encouraged throughout the main trial. Blood samples were taken before the exercise (following overnight fasting) and immediately, 10 min, and 30 min after the exercise protocol from an antecubital vein.
The blood samples were transferred to four aliquots: the first vials containing EDTA were left at room temperature for 2 hours, and then they were used for measuring hemoglobin and hematocrit using automated Coulter Counter (Sysmex k-x21) in order to correct plasma volume shifts [
Serum cortisol level was measured using chemiluminescent immunoassay and a commercial kit (Liaison, USA). Creatine kinase activity was measured by spectrophotometry using a commercial kit (Pars Azmoon Lab, Iran).
High-performance liquid chromatography (HPLC) with fluorescence detection was used for plasma (with minor modifications) [
For any measurements in RBCs, first 100
The results are presented as mean ± SEM, except for subject characteristics, which are presented as mean ± SD. All data were analyzed for their normal distribution using KS test. Subject characteristics, dietary data, and estimated percentage of changes in plasma volume were analyzed by using ANOVA. A univariate GLM for repeated measures was used to analyze the differences within groups and for fixed between-groups factors, Bonferroni test was used for multiple comparison tests. Also, ANOVA with Tukey post hoc test was used to analyze the differences between and within groups. Calculations were performed with the SPSS, Version 20.0 (SSPS Inc., Chicago, IL), statistical package. Statistical significance was defined as
The physiological characteristics of the participants are represented in Table
Estimated percentage of changes in plasma volume in the groups of WT, MT, and UT.
Parameter | Pre-exs | Post-exs | Post-10 min | Post-30 min |
|
|
---|---|---|---|---|---|---|
Plasma volume change, WT group | — | −0.71 ± 1.80 | 2.63 ± 1.47 | 2.78 ± 1.55 | 0.087 | 0.917 |
MT group | — | −0.78 ± 0.53 | 1.70 ± 1.30 | 1.41 ± 1.47 | 1.242 | 0.305 |
UT group | — | −0.49 ± 1.22 | 0.85 ± 1.97 | −0.68 ± 2.28 | 0.939 | 0.403 |
Data are mean ± SEM.
Dietary intake assessment during the 3-day period prior to the main trial.
WT group | MT group | UT group |
|
|
|
---|---|---|---|---|---|
Kilocalories | 2817.40 ± 220.66 | 2864.70 ± 156.16 | 2455.20 ± 110.29 | 1.766 | 0.190 |
Protein | 106.11 ± 10.17 | 106.27 ± 6.35 | 96.34 ± 5.46 | 0.558 | 0.579 |
Carbohydrate | 466.65 ± 47.43 | 421.49 ± 33.24 | 348.58 ± 31.41 | 2.452 | 0.105 |
Fat total | 59.49 ± 3.44 | 77.61 ± 2.60 | 70.75 ± 8.50 | 2.760 | 0.081 |
SFA | 18.79 ± 2.45 | 23.35 ± 2.65 | 17.19 ± 2.99 | 1.388 | 0.267 |
MUFA | 16.14 ± 2.82 | 24.72 ± 2.20 | 18.71 ± 2.77 | 2.829 | 0.077 |
PUFA | 14.26 ± 2.27 | 20.10 ± 2.61 | 21.12 ± 4.10 | 1.423 | 0.258 |
Vitamin C | 39.48 ± 9.56 | 42.54 ± 10.61 | 57.32 ± 20.85 | 0.427 | 0.657 |
Vitamin E | 15.91 ± 2.96 | 24.62 ± 2.68 | 18.82 ± 2.53 | 2.630 | 0.090 |
Vitamin A total | 251.41 ± 34.32 | 213.55 ± 29.45 | 153.48 ± 30.66 | 2.450 | 0.105 |
Carotene | 79.40 ± 9.01 | 74.30 ± 9.16 | 51.70 ± 9.79 | 2.496 | 0.101 |
Selenium | 0.05 ± 0.01 | 0.08 ± 0.02 | 0.06 ± 0.01 | 0.593 | 0.560 |
Gram quantities for each macronutrient are provided. Vitamin C and vitamin E are provided in milligrams. Vitamin A values are provided in retinol equivalents. Data are mean ± SEM.
Table
Biochemical parameters.
Time | WT group (mean ± SEM) | MT group (mean ± SEM) | UT group (mean ± SEM) | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Pre | Post | 10 | 30 | Pre | Post | 10 | 30 | Pre | Post | 10 | 30 | ||
Plasma | Cys | 9.90 ± 0.80 | 8.65 ± 0.91 | 9.12 ± 0.86 | 9.68 ± 0.86 | 13.79 ± 0.69 |
11.87 ± 0.69 |
12.65 ± 0.63 |
13.48 ± 0.68 |
12.11 ± 0.35 | 10.88 ± 0.45 | 11.32 ± 0.33 | 12.03 ± 0.34 |
CySS | 56.04 ± 5.82 | 65.94 ± 6.72 | 63.02 ± 6.44 | 58.85 ± 5.75 | 56.03 ± 6.25 | 62.71 ± 6.11 | 60.96 ± 5.93 | 58.21 ± 5.86 |
78.56 ± 6.37 |
96.61 ± 8.85 |
89.23 ± 7.40 |
82.04 ± 7.12 | |
GSH | 1.98 ± 0.34 | 1.60 ± 0.25 | 1.73 ± 0.27 | 1.93 ± 0.36 | 3.22 ± 0.29 |
3.01 ± 0.38 |
2.65 ± 0.20 |
3.02 ± 0.28 |
1.80 ± 0.31 | 1.56 ± 0.26 | 1.57 ± 0.20 | 1.71 ± 0.27 | |
GSSG | 0.04 ± 0.00 | 0.59 ± 0.09 | 0.31 ± 0.05 | 0.04 ± 0.00 | 0.05 ± 0.00 | 0.66 ± 0.10 | 0.36 ± 0.05 | 0.05 ± 0.00 | 0.050 ± 0.00 | 0.63 ± 0.10 | 0.34 ± 0.05 | 0.05 ± 0.00 | |
RBCs | GSH | 2.11 ± 0.25 | 2.87 ± 0.23 | 2.57 ± 0.16 | 2.34 ± 0.14 | 2.29 ± 0.13 | 3.01 ± 0.16 |
2.65 ± 0.15 | 2.22 ± 0.15 | 2.52 ± 0.16 | 2.24 ± 0.15 | 2.33 ± 0.18 | 2.49 ± 0.17 |
GSSG | 0.12 ± .01 | 0.15 ± 0.01 | 0.14 ± 0.01 | 0.13 ± 0.01 | 0.08 ± 0.01 | 0.08 ± 0.01 |
0.08 ± 0.01 |
0.08 ± 0.01 | 0.10 ± 0.01 | 0.13 ± 0.01 | 0.13 ± 0.1 | 0.10 ± 0.01 | |
Cortisol | 10.11 ± 1.38 | 14.24 ± 1.24 | — | — | 12.65 ± 1.36 | 16.08 ± 1.54 | — | — | 11.78 ± 0.98 | 14.77 ± 1.05 | — | — | |
Creatin kinase | 167.20 ± 15.25 | 185.20 ± 15.25 | — | — | 150.20 ± 17.62 | 172.50 ± 20.23 | — | — | 148.00 ± 24.02 | 167.4 ± 23.42 | — | — |
The superscript symbols indicate a significant between-groups difference tested by ANOVA with Tukey post hoc test and a significant within-groups difference tested by ANOVA for repeated measure with the following
Table
As Figure
Effects of one session of aerobic exercise on plasma Cys/CySS in subjects with different physical training status. Values represent mean ± SEM (
Plasma level of GSH in MT group was significantly greater than in WT and UT groups in pre-exs (
Effects of one session of aerobic exercise on plasma GSH/GSSG in subjects with different physical training status: values represent mean ± SEM.
Red blood cells GSH level was increased in MT (
The changes of GSH/GSSG in RBCs are shown in Figure
Effects of one session of aerobic exercise on GSH/GSSG ratio in red blood cell (RBC) in subjects with different physical training status: values represent mean ± SEM (
The aim of this study was to evaluate the changes in glutathione redox ratio expressed as GSH/GSSG and Cys/CySS in plasma and also GSH/GSSG in RBCs in subjects with different physical training status. Our results showed that physical training status affected the plasma GSH/GSSG and Cys/CySS ratio and RBCs GSH/GSSG ratio at baseline and after exercise.
All groups experienced one session of physical stress and showed cortisol elevation without significant between-groups differences, excluding the possibility of hypothalamus-adrenal axis adaptation in WT group [
Also, this finding confirms that exercise with 75% Vo2max can be a physiological stress for all subjects independently of their physical fitness status. This finding is in agreement with other previous studies [
No significant difference in preexercise values of CK reflects that groups were well matched in terms of previous muscle damage and inflammation. Following exercise, CK showed elevation in all groups with no between-groups differences. Elevation in serum creatine kinase in all groups probably reflects exercise-induced muscle damage in sarcomeres Z disk [
Preexercise analysis revealed the highest level of plasma GSH and GSH/GSSG in MT group with moderate Vo2max (
As mentioned before, glutathione couple GSH/GSSG is a critically important redox biomarker [
In addition, plasma analysis revealed a significant reduction in GSH/GSSG and Cys/CySS in all groups, reflecting exercise-induced oxidative stress. Considering the fact that GSH/GSSG and Cys/CySS couples in blood plasma stand for clinical measure of oxidative stress [
Regarding the fact that changes in plasma thiols, especially oxidized glutathione and GSH/GSSG ratio, have been used as markers of oxidative stress status in biological systems [
Finally, RBCs GSH/GSSG ratio showed no change, elevation, and reduction in WT, MT, and UT groups, respectively. The lowest level of RBC GSH/GSSG and the highest level of GSSG in WT group compared with other groups indicate the lowest reducing power in red blood cells in this group. The possible explanation for this finding might be that chronic production of free radicals may overwhelm the capacity of the antioxidant defense system and leads to a permanent shift in redox balance towards a more oxidizing environment [
In moderately trained subjects, RBCs GSH/GSSG ratio was increased following exercise. This increase was secondary to increase in GSH and decrease in GSSG. The exact physiologic mechanisms of this increase have not been understood yet [
In untrained young men (UT group), the GSH level and GSH/GSSG ratio in RBCs decreased and GSSG level increased following exercise. Thus, these participants are predicted to suffer from inadequate level of RBCs antioxidant protection system encountering exercise and are predisposed to RBC damage and further related diseases [
It is important to notice that selected body fluid is important in detection of redox biomarkers [
It is important to notice that distribution of GSH and GSSG among body fluids and tissues is not equal. For example, in our study, the concentration of GSH in RBCs of UT and WT groups was 1400- and 12300-fold higher than plasma, which confirms the previous report about fluid and tissue GSH relationship [
Our results point to the conclusion that the effect of high intensity acute exercise on glutathione redox ratio depends on physical training status of individuals. Therefore, it seems that a lifestyle with moderate regular exercise training will improve health by shifting in “redox” balance towards more reducing environment, encountering stressful conditions.
The authors declare that no competing financial interests exist.
Gratitude is expressed to the subjects who participated in this study.