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antioxidant enzyme activities, and muscle damage in the same and different exercise ... The changes in (MDA) and glutathione (GSH) levels and superoxide ...
CHANGES IN LIPID PEROXIDATION AND ANTIOXIDANT CAPACITY DURING WALKING AND RUNNING OF THE SAME AND DIFFERENT INTENSITIES S xU¨KRU¨ SERDAR BALCı,1 NILSEL OKUDAN,2 HAMDI PEPE,3 HAKKı GO¨KBEL,2 SERKAN REVAN,3 FIRUZE KURTOG˘LU,4 AND HASAN AKKUSx1 1

Department of Trainer Education, School of Physical Education and Sports, Selcxuk University, Aleaddin Keykubat Campus; Meram Faculty of Medicine, Department of Sports Physiology, Selcxuk University; 3Department of Physical Education and Sports, School of Physical Education and Sports, Selcxuk University, Aleaddin Keykubat Campus; and 4Department of Biochemistry, Faculty of Veterinary Medicine, Selcxuk University, Aleaddin Keykubat Campus, Konya, Turkey

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ABSTRACT Balcı, SS, Okudan, N, Pepe, H, Go¨kbel, H, Revan, S, Kurtog˘lu, F, and Akkusx, H. Changes in lipid peroxidation and antioxidant capacity during walking and running of the same and different intensities. J Strength Cond Res 24(9): 2545–2550, 2010— The aim was to investigate the changes in lipid peroxidation, antioxidant enzyme activities, and muscle damage in the same and different exercise intensities during walking and running. Fourteen healthy males participated in this study. The subjects’ individual preferred walk-to-run transition speeds (WRTS) were determined. Each subject covered a 1.5-mile distance for 4 exercise tests; walking (WRTS-W) and running (WRTS-R) tests at WRTS, 2 kmh21 slower walking than WRTS (WRTS-2) and 2 kmh21 faster running than WRTS (WRTS+2). Blood samples were taken pre, immediately, and 30 minutes post each test. The changes in (MDA) and glutathione (GSH) levels and superoxide dismutase (SOD), catalase (CAT), and creatine kinase activities were measured. Oxygen uptake, carbon dioxide output, oxygen uptake per kilogram of body weight, and heart rate during exercises were significantly higher in both the WRTS-W and the WRTS+2 exercises compared with the WRTS-2 and WRTS-R. Oxygen consumption and energy expenditure were higher in walking than in the running exercise at the preferred WRTS and only WRTS-W exercise significantly increased MDA levels. Catalase activities were increased by WRTS-W, WRTS-R, and WRTS+2 exercises. Changes in SOD and CAT activities were not different between walking and running exercises at the preferred WRTS. Total plasma GSH increased in response to WRTS-W exercise, which could be associated with an increase in MDA. Also, total GSH levels

Address correspondence to Sxu¨kru¨ Serdar Balci, [email protected]. 24(9)/2545–2550 Journal of Strength and Conditioning Research Ó 2010 National Strength and Conditioning Association

30 minutes postexercise were significantly lower than postexercise in WRTS-2, WRTS-W, and WRTS+2 exercises. Our results indicate that walking and running exercises at the preferred WRTS have different oxidative stress and antioxidant responses.

KEY WORDS lipid peroxidation, endogenous antioxidants, walking, running, activity intensity INTRODUCTION

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hysical exercise, especially under circumstances such as unaccustomed intensity or duration, increases the production of reactive oxygen species (ROS) and leads to oxidative stress, even in trained individuals (23). Exercise increases whole-body oxygen consumption, particularly skeletal muscle compared with the resting state (28). The increased oxygen consumption during exercise can increase ROS. Other sources of ROS that increase with exercise include prostanoid metabolism, xanthine oxidase, NAD(P)H oxidase, and several secondary sources, such as the release of radicals by macrophages recruited to repair damaged tissue (35). Exercise-induced ROS production has been shown to be intensity dependent (2,11,13). That is lower intensity exercise may not be sufficient to elicit a significant oxidative stress. Cells continuously produce ROS as part of their metabolic processes, but the majority of ROS are neutralized by the antioxidant defense system. Reactive oxygen species play an important role in cellular signals because they can serve as cell messengers or modify oxidation-reduction status (26). The antioxidant defense system includes both endogenous and exogenous antioxidants. Endogenous antioxidants include superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase, and glutathione (GSH). These antioxidants can be activated by an acute bout of exercise at sufficient intensity (11). This can be considered as a defensive mechanism of the cell under oxidative stress (4,9,22). It is not fully known whether natural antioxidant defense system of the body is VOLUME 24 | NUMBER 9 | SEPTEMBER 2010 |

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Changes in Lipid Peroxidation and Antioxidant Capacity sufficient to counteract the increase in exercise-induced ROS, although trained athletes who received antioxidant supplements show evidence of reduced oxidative stress (7). The degree of change in oxidative stress and antioxidant status biomarkers is dependent on a number of factors related to the actual exercise itself, the subject population, and analytical procedures used in testing the outcome measures (5). Two primary modes of locomotion commonly used by humans are walking and running. Walking is a preferred movement pattern at lower speeds, whereas running typically characterizes locomotion at higher speeds (33). Walking is the most important form of physical activity that should be encouraged to improve public health given that walking and running are the activities most widely available (10,15). As the velocity of locomotion increases, there exists a speed at which transition from a walk to a run occurs. This juncture is commonly referred to as the walk-run transition speed (WRTS) or the preferred transition speed (33). In previous reports, acute physical activities such as running, cycling, swimming, and eccentric exercise have been shown to increase ROS production in humans (1,6,17,24). However, information on the production of ROS as a result of walking is lacking compared with running and other types of exercise. Revealing the effects of different intensities of frequently used physical activities such as walking and running on oxidative stress is important for exercise prescription. For these reasons, the aim of the present study was to investigate the effects of both walking and running at the same and different speeds on lipid peroxidation, antioxidant defenses, and muscle damage.

METHODS Subjects

A total of 14 male university students (22.9 6 0.5 years old) participated voluntarily in this study. None of the students were involved in any regular training program before this study. All of the participants were nonsmokers, and for at least 3 months before the study, they had not taken any vitamins, minerals, or medications affecting oxidative stress markers. All subjects provided informed written consent. The study was approved by the Ethical Committee of the School of Physical Education and Sports of Selcxuk University. Determination of Maximum Oxygen Consumption

Each subject visited the laboratory 6 times. In the first session, the Bruce Treadmill Protocol was used to determine maximum oxygen consumption (V_ O2max) (8). All subjects were accustomed to walking and running on a treadmill (Cosmed T150E, Rome, Italy) before the beginning of the study. Determination of Preferred Walk-to-Run Transition Speed

During first session, preferred transition speed was determined using a modification of the protocol employed by Rotstein et al. (29). The subjects’ individual preferred WRTS was determined. This was defined as the lowest velocity at which the subject chose to start running. For this purpose, the

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treadmill speed was initially set at a comfortable walking speed of 5 kmh21, which was increased by 0.5 kmh21 every minute. Subjects were asked to walk as long as they were comfortable and to start running at a particular speed they felt running was more comfortable. At the point where running was initiated, the subject was asked by the researcher to run for 1 minute and then walk for 1 minute at that same speed. These walking-running intervals were repeated at least twice until the subject was sure that this WRTS was preferred. If the subject decided to walk, the speed was increased to the next higher level and the walking-running 1-minute interval procedure was repeated until the subject was certain that running was preferred. Walking and Running tests

All walking and running tests were separated by at least 48 hours. Each subject was tested at the same time of the day (9:00–12:00 AM), to minimize the effects of diurnal biological variation. Each subject covered a 1.5-mile distance for 4 exercise tests; walking (WRTS-W) and running (WRTS-R) tests at WRTS 2 kmh21 slower walking than WRTS (WRTS2) and 2 kmh21 faster running than WRTS (WRTS+2). The expired air was measured and analyzed breath by breath using an automated online system (Quark B2 system, Cosmed Srl, Rome, Italy) and heart rate was monitored and recorded throughout walking and running tests. Subjects were instructed not to change their physical activity, dietary habits, or any other aspects of their lifestyle during the study. Blood Sample Collection

Blood samples were taken from each of the healthy volunteers before, immediately, and 30 minutes post all walking and running tests. Blood was drawn from the antecubital vein into a 10-mL Vacutainer tube (with Ethylene Diamine Tetra-acetic Acid [EDTA]). Plasma was obtained by centrifugation of blood at 2,500 rpm for 10 minutes at +4°C. Plasma was then stored at – 80°C until analysis. Malondialdehyde Assay

Lipid peroxides, derived from Polyunsaturated Fatty Acid (PUFA), include reactive carbonyl compounds, of which the most abundant is MDA. The MDA-586 (Bioxytech Cat Number 21044) method serves to minimize interference from other lipid peroxidation products, such as 4-hydroxyalkenals. This method is based on the reaction of a chromogenic reagent, N-methyl-2-phenylindole, with MDA at 45°C. Glutathione Assay

Glutathione values of plasma were determined by Cayman’s assay kits (Cat Number: 703002) using GSH reductase, for the quantification of GSH. Superoxide Dismutase (EC 1.151.1)

Superoxide dismutase activities of plasma were measured by a Cayman SOD Assay Kit (706002) utilizing a tetrazolium salt for detection of superoxide radicals generated by xanthine oxidase and hypoxanthine. One unit of SOD is defined as the

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phosphate (NADPH) formation, measured photometrically, is proportional to the catalytic concentration of creatine kinase (CK) present in the plasma.

TABLE 1. Characteristics of the subjects (n = 14). Age (y) Height (cm) Weight (kg) Body mass index (kg/m2) Leg length (cm) V_ O2max (mlkg21min21) WRTS* (kmh21) HR at WRTS (bmin21)

22.9 171.2 69.6 23.8 86.9 56.7 9.37 184.2

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(0.5) (2.0) (2.0) (0.6) (1.1) (1.0) (0.22) (3.3)

Statistical Analysis

Values are mean (SEM). *WRTS = preferred walk-to-run transition speed; HR = heart rate.

amount of enzyme needed to exhibit 50% dismutation of the superoxide radical. The SOD assay measures all 3 types of SOD (Cu/Zn-, Mn-, and Fe-SOD). Catalase (EC 1.11.1.6; 2H2O2 Oxidoreductase)

Catalase activity was measured by Cayman’s CAT Assay Kit (Cat No. 707002), an agent utilizing the peroxidatic function of CAT for the determination of enzyme activity. The method is based on the reaction of the enzyme with methanol in the presence of an optimal concentration of H2O2. The formaldehyde produced is measured spectrophotometrically with 4-amino-3-hydrazino-5-mercapto-1, 2, 4-triazole as the chromogen. Purpald specifically forms a bicyclic heterocycle with aldehydes, which, on oxidation, changes from colorless to a purple color. Creatine Kinase

This enzyme was spectrophotometrically measured by using a commercial test kit [SPINREACT, S.A. Ctra.Santa Coloma, 7 E-17176 Sant Esteve De Bas (GI) Spain. Ref. Number 41250]. The rate of nicotinamide adenine dinucleotide

The data were tested for normal distribution with the Kolmogorov-Smirnov test and for homogeneity of variances with Levene’s test. Biochemical data were analyzed by a 2-factor repeated measures analysis of variance (ANOVA), followed by Bonferroni’s post hoc intragroup comparisons. When the exercise 3 time and time interaction p value was p # 0.05, the change from pre-exercise, postexercise, and recovery period values was calculated and compared with 1-way repeated measures ANOVA. A 1-way repeated measures ANOVA with a Bonferroni post hoc test was used to compare the pulmonary-gas exchange and heart rate during the walking and running tests. The ANOVA was run using the SPSS 15.0 for Windows statistical package. Results were reported as the mean (SEM) of all observations, with the level of significance set at p , 0.05.

RESULTS The physical characteristics and preferred WRTS data of the subjects are presented in Table 1. Table 2 gives the descriptive data showing exercise time, oxygen uptake, carbon dioxide output, oxygen uptake per kilogram of body weight, heart rate, and energy expenditure during walking and running exercise tests in the subjects. All variables (except exercise time) were significantly higher in both the WRTS-W and the WRTS+2 exercises compared with the WRTS-2 and WRTS-R exercises and in the WRTS+2 exercise compared with the WRTS-2 exercise. Table 3 shows the effect of walking and running exercises on MDA and GSH levels and SOD, CAT, and CK activities in plasma. WRTS-W postexercise MDA levels were significantly higher than pre-exercise levels (p , 0.05). Superoxide

TABLE 2. Pulmonary-gas exchange during the walking and running exercises. Walking WRTS-2 Exercise time (min:s) V_ O2 (mlmin21) 21 _ ) VCO 2 (mlmin _VO2/kg (mlkg21min21) HR (bmin21) METs

19:52 (0:36) 1831.4 (18.4)a 1695.0 (17.7)a 26.52 (0.27)a 129.9 (0.7)a 7.58 (0.08)a

Running WRTS-W

15:34 3092.4 3071.9 44.55 176.4 12.73

(0:22) (27.0)b (27.9)b (0.35)b (0.9)b (0.10)b

WRTS-R

WRTS+2

F

15:34 (0:22) 2492.5 (16.6)c 2338.6 (17.2)c 35.84 (0.21)c 149.5 (0.5)c 10.24 (0.06)c

12:48 (0:15) 2820.9 (21.4)b 2729.2 (820.2)b 40.66 (0.28)b 168.0 (0.5)b 11.62 (0.08)b

— 473.35* 447.97* 590.65* 3254.73* 590.65*

Values are means (SEM) for each test. *p , 0.05, compared between walking and running tests (a one-way repeated measures analysis of variance, ANOVA). a–d Different superscript letters in the same row indicate a significant difference (ANOVA with a Bonferroni post hoc test; WRTS-2, 2 kmh21slower walking than WRTS; WRTS-W, walking at WRTS; WRTS-R, running at WRTS; WRTS+2, 2 kmh21 faster running than WRTS. METs = metabolic equivalents.

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Changes in Lipid Peroxidation and Antioxidant Capacity

TABLE 3. Changes in MDA and GSH levels and SOD, CAT, and CK activities during walking and running exercises. F

MDA (mM)

SOD (U/mL)

CAT (nmol/min/mL)

GSH (mM)

CK (U/L)

WRTS-2 WRTS-W WRTS-R WRTS+2 WRTS-2 WRTS-W WRTS-R WRTS+2 WRTS-2a WRTS-Wb WRTS-Rc WRTS+2a,c WRTS-2 WRTS-W WRTS-R WRTS+2 WRTS-2 WRTS-W WRTS-R WRTS+2

Pre-exercise

Postexercise

30-min recovery

7.30 6.77 6.48 7.29 0.03 0.03 0.04 0.03 74.05 70.86 69.53 85.78 3.33 1.96 1.72 3.10 33.60 39.27 33.17 28.95

7.14 (0.45) 7.55 (0.38)† 7.49 (0.44) 7.21 (0.34) 0.03 (0.01) 0.04 (0.01) 0.03 (0.00) 0.03 (0.00) 80.39 (3.93) 93.11 (4.15)† 86.19 (1.85)† 98.02 (3.78)† 3.37 (0.52) 3.45 (0.52)† 2.49 (0.33) 3.62 (0.41) 37.34 (4.52) 44.82 (5.25) 33.99 (3.04) 35.29 (4.17)†

7.47 (0.40) 6.76 (0.37) 7.24 (0.82) 7.20 (0.41) 0.03 (0.01) 0.04 (0.00)† 0.03 (0.00) 0.04 (0.00) 79.31 (4.22) 82.72 (3.76)‡ 81.09 (3.12) 89.24 (4.22) 2.34 (0.45)† ‡ 1.96 (0.43)‡ 2.37 (0.50) 2.56 (0.38)‡ 43.17 (6.23) 39.17 (4.77) 31.51 (4.04) 39.03 (5.23)†

(0.48) (0.37) (0.49) (0.45) (0.00) (0.00) (0.00) (0.00) (3.50) (5.58) (4.43) (2.58) (0.48) (0.23) (0.30) (0.51) (3.69) (5.52) (5.10) (3.75)

Time

Exercise time

Exercise

1.39

1.12

0.12

1.96

1.49

1.22

25.11*

1.64

3.75*

11.73*

2.52*

1.41

4.13*

2.04

0.75

Values are means (SEM) for each test. WRTS-2 = 2 kmh21slower walking than WRTS; WRTS-W = walking at WRTS; WRTS-R = running at WRTS; WRTS+2 = 2 kmh21 faster running than WRTS. CK = creatine kinase; GSH = glutathione; CAT = catalase; SOD = superoxide dismutase; MDA = malondialdehyde; and ANOVA = analysis of variance. The same superscript letters (a–c) in the same column indicate significant difference with exercise for CAT activities (ANOVA with a Bonferroni post hoc test). *p , 0.05, compared between walking and running tests (2-way repeated measures ANOVA). †p , 0.05, significantly different from pre-exercise levels. ‡p , 0.05, significantly different from postexercise levels.

dismutase activity was significantly higher in the recovery period after exercise than in pre-exercise in WRTS-W (p , 0.05). No significant time, exercise, or interaction effects were observed for MDA and SOD in pre, immediately, and 30 minutes post of the WRTS-W exercise. Catalase activity was significantly increased by WRTS-W, WRTS-R, and WRTS+2 exercises. There was a significant time (F = 25.11; p , 0.05) and exercise (F = 3.75; p , 0.05) effect for CAT but no significant interaction effect. Post hoc analysis revealed that there were significant differences between the WRTS-2, WRTS-R, and WRTS+2 exercises. There were significant differences in GSH levels between immediately, pre, and 30 minutes post in WRTS-2, and between pre, 30 minutes post, and immediately in WRTS-W, and between immediately and 3 minutes post in WRTS+2. There was no significant exercise effect for GSH level, but there were significant interaction (F = 2.52; p , 0.05) and time effects (F = 11.73; p , 0.05) among the exercises. There was a significant time effect (F = 4.13; p , 0.05) for CK activities but no significant exercise and interaction effect, and there

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were significant differences between immediately, 30 minutes post and pre in WRTS+2.

DISCUSSION This study was designed to examine the effects of walking and running exercises of different intensities on oxidative stress in plasma. It is well known that different forms of exercise result in oxidative stress of different severities. Few studies investigated either the acute or chronic effects of walking exercise on biomarkers of lipid peroxidation and antioxidants; however, there was no research on walking-induced oxidative stress. It has been generally accepted that the transition from a walk to a run serves to reduce the metabolic stress of locomotion. We found that oxygen consumption and energy expenditure were higher in walking than in the running exercise at the preferred WRTS and only WRTS-W exercise significantly increased the MDA levels. However, the MDA levels in WRTS-W returned to the resting level after 30 minutes. The increased oxidative stress with acute exercise is

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Journal of Strength and Conditioning Research a result of the dramatic increase in oxygen consumption of the cells that occur during heavy exercise (20). However, MDA changes after exercises were not significantly different between walking and running exercises in the present study. Exercise-induced ROS production depends on the exercise intensity. High-intensity exercise caused more lipid peroxidation compared with moderate or low-intensity exercises (14,25,31). This is showed by an increase in plasma MDA (25,31) and 8-isoprostane (an index of oxidative stress) (14) concentrations. Lipid peroxidation seems to be an important mechanism underlying exercise-induced muscle damage and a large number of studies have reported correlations between plasma CK release and lipid peroxidation (21,36). In the present study, plasma CK was significantly higher postexercise (immediately and 30 minutes post) during WRTS+2 exercise only. Although MDA increased from pre to postexercise during WRTS-W, CK activities did not change. Thus, our results show that plasma CK changes are not related to exercise intensity and/or type. The extent of oxidative damage generated during physical exercise is determined not only by the level of ROS generation but also by the defense capacity of antioxidants. Superoxide dismutase and CAT provide the primary defense against ROS generated during exercise, and activities of these enzymes are known to increase in response to exercise (18). Superoxide dismutase is one of the main antioxidant enzymes that degrade ROS. Our results of total SOD activity changes in plasma did not show differences between walking and running exercises. An acute bout of exercise has been shown to increase the activity of SOD in a number of tissues (19), and blood and red blood cells (27). The increase in activity of total SOD was significantly higher in the recovery period than pre-exercise in high-intensity WRTS-W exercise. However, Schneider et al. indicated that in an untrained group SOD activities were significantly increased after exercise at low and moderate intensities and that a nonsignificant increase was observed at high intensities (30). Wang et al. (34) reported that no significant change was observed in plasma SOD activity after mild, moderate, and heavy exercise. In our study, SOD activity increased along with MDA during high-intensity WRTS-W exercise, but there was no difference in this parameter with the other exercise tests. Superoxide dismutase catalyzes the reaction of the superoxide radical to hydrogen peroxide (H2O2), whereas CAT removes the H2O2 by converting it to H2O and O2 (22). Numerous studies have indicated nonsignificant changes in CAT activities with acute exercise at different intensities (19,30,32). Besides the exceptions, CAT activities have also been observed to increase significantly after exhaustive or high-intensity exercise (1,17). In the present study, CAT activities were increased by WRTS-W, WRTS-R, and WRTS+2 exercises. Also, changes in CAT activities were not different between walking and running exercises at the

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preferred WRTS. Catalase activities decreased at the recovery period as compared with the postexercise, at WRTS-W. These results would suggest that exercise intensity is an important factor in terms of affecting CAT activity. Glutathione plays an important role in the regulation of lipid oxidation in plasma (3). Changes in the glutathione system have been assessed because GSSG efflux from cells into the plasma is considered an indicator of oxidative stress. Glutathione is oxidized to GSSG in cells in response to an increase in ROS (7). The study by Wang et al. (34) indicated that no significant increase was observed in total plasma GSH activity after low, moderate, and high-intensity exercises. However, another study (12) states that GSH plays a central antioxidant role in blood during intensive physical exercise and that its modifications are closely related _ to exercise intensity. Ilhan et al. (16) observed that blood GSH levels were not significantly different between pre and postexercise periods in aerobic, anaerobic, and aerobic + anaerobic dominant exercise groups. We found that plasma total GSH increased in response to WRTS-W exercise and it could be associated with increases in MDA. Also, total GSH levels at the recovery period were significantly lower than postexercise levels in WRTS-2, WRTS-W, and WRTS+2 exercises. Our results suggest that total plasma GSH alterations are closely related to exercise intensity and/or type. In conclusion, evidence from the present study suggests that lipid peroxidation is greatest during walking, when compared with running at the same workload, likely due to an increase in metabolic stress during the former. For coping with the metabolic load, there are some increases in antioxidant enzymes at speeds equal to or higher than the preferred WRTS differently from slow walking. Our findings showed that walking and running exercises at the preferred WRTS have different oxidative stress responses. Because of lower oxidative load, our suggestion is to choose running rather than walking at or near the preferred WRTS.

ACKNOWLEDGMENTS This study was supported by the Selcxuk University Scientific Research Projects (S.U.-BAP, Konya, Turkey) (Project no: 6401063).

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