Research Article: Changes in Non-Enzymatic Antioxidants in the Blood Following Anaerobic Exercise in Men and Women

Date Published: November 24, 2015

Publisher: Public Library of Science

Author(s): Magdalena Wiecek, Marcin Maciejczyk, Jadwiga Szymura, Zbigniew Szygula, Malgorzata Kantorowicz, Guillermo López Lluch.

http://doi.org/10.1371/journal.pone.0143499

Abstract

The aim of this study was to compare changes in total oxidative status (TOS), total antioxidative capacity (TAC) and the concentration of VitA, VitE, VitC, uric acid (UA), reduced (GSH) and oxidized glutathione (GSSG) in blood within 24 hours following anaerobic exercise (AnEx) among men and women.

10 women and 10 men performed a 20-second bicycle sprint (AnEx). Concentrations of oxidative stress indicators were measured before AnEx and 3, 15 and 30 minutes and 1 hour afterwards. UA, GSH and GSSH were also measured 24 hours after AnEx. Lactate and H+ concentrations were measured before and 3 minutes after AnEx.

The increase in lactate and H+ concentrations following AnEx was similar in both sexes. Changes in the concentrations of all oxidative stress indicators were significant and did not differ between men and women. In both sexes, TOS, TAC, TOS/TAC and VitA and VitE concentrations were the highest 3 minutes, VitC concentration was the highest 30 minutes, and UA concentration was the highest 1 hour after AnEx. GSH concentration was significantly lower than the initial concentration from 15 minutes to 24 hour after AnEx. GSSG concentration was significantly higher, while the GSH/GSSG ratio was significantly lower than the initial values 1 hour and 24 hour after AnEx.

With similar changes in lactate and H+ concentrations, AnEx induces the same changes in TAC, TOS, TOS/TAC and non-enzymatic antioxidants of low molecular weight in men and women. Oxidative stress lasted at least 24 hours after AnEx.

Partial Text

Peak anaerobic power is significantly higher in men than in women [1] due to a greater mass of skeletal muscles in the former [2] and differences related to the histology and metabolic activity of myocytes among the sexes [3–6]. While the share of slow-twitch and fast-twitch muscle fibers in skeletal muscles is similar in both sexes [7], men show a greater cross-sectional area of fast-twitch fibers [3], higher ratios between the cross sections of the following pairs of fiber types: IIA/I, IIB/I and IIB/IIA [8] and, consequently, a greater share of Type II (MyHC II) myosin heavy chains than women [6]. The share of Type II fibers and peak anaerobic power correlate positively with the level of post-exercise oxidative stress [9]. Oxidative stress results from a disrupted balance between oxidation processes involving reactive oxygen species (ROS) and reactive nitrogen species (RNS), and the enzymatic and non-enzymatic antioxidant defense [10]. Upregulation of ATP resynthesis during sprinting leads to a considerable increase in AMP/ATP and lactate/pyruvic acid concentration ratios, a decrease in phosphocreatine concentration and a decrease in the NAD+/NADH concentration ratio in myocytes [11]. In turn, the increase in AMP/ATP concentration ratio leads to an increase (following anaerobic exercise) in purine metabolism involving xanthine oxidase and a shift in the prooxidant-antioxidant balance towards oxidation, caused by excessive production of the following types of ROS: the superoxide anion radical (O2•-), hydrogen peroxide (H2O2) and the hydroxyl radical (•OH) [12]. ROS and RNS are also produced during myocyte contraction due to the activation of NADPH oxidase and nitric oxide synthase [12]. A significant positive correlation was observed between the increase in lactate concentration in blood plasma following exercise and the increase in total oxidative status of blood plasma expressed through lipid peroxide concentration [13]. The activity of anaerobic metabolism enzymes is greater in men than in women [4,5,8]. As a result, men display greater disruptions to the acid-base balance in the blood following anaerobic exercise [14,15]. Catecholamine concentration in the blood is also higher in men than in women following anaerobic exercise [15], which may intensify oxidative stress in the former [16]. On the other hand, a significant, yet similar in both sexes, increase in AMP-activated protein kinase (AMPK) phosphorylation was found in muscles following anaerobic exercise [17]. Because AMPK activates nitric oxide synthesis [18], its increased phosphorylation may indicate that both sexes undergo a similar post-exercise increase in RNS concentration.

The study project was approved by the Commission for Bioethics at the Regional Medical Chamber in Krakow, Poland (opinion No. 81/KBL/OIL/2013). The study was conducted according to the Declaration of Helsinki. Study participants were informed about the aim of the study, laboratory conditions, equipment and research procedures, and gave written consent for voluntary participation in the project. The participants underwent medical qualification that involved taking their medical history, blood count and ECG screening to eliminate medical contraindications to performing maximal and anaerobic exercise. In addition, women underwent a gynecological interview to confirm that their menstrual cycles were regular and that they took no hormonal drugs. All exercise tests were conducted under the supervision of a physician specializing in sports medicine.

Men achieved significantly higher values of PP and MP (absolute and relative to BM) during AnEx than women (Table 2). The increase in H+ concentration in the blood and Lac concentration in blood plasma following AnEx was significant (p < 0.001) and did not differ significantly between sexes (ΔH+: 23.68±3.45 nmol·L-1 in men and 17.70±1.29 nmol·L-1 in women; ΔLac: 12.21±0.48 mmol·L-1 in men and 11.00±0.77 mmol·L-1 in women). Significant post-exercise changes in the concentrations of all oxidative stress indicators were found in men and women (Table 3; Figs 1–10). Changes in the concentrations of the analyzed oxidative stress indicators were similar in both sexes. No significant sex-anaerobic exercise interaction was found (Table 3). Both sexes showed the highest concentrations of TOS, TAC, Vit A and Vit E in blood plasma and OSI three minutes after AnEx (Rec 3). Vit C concentration in blood plasma and UA concentration in the serum increased continuously following AnEx and reached maximal values 30 and 60 minutes after AnEx, respectively, in both sexes. Beginning with the 15th minute after AnEx, both sexes showed a significant decrease (p < 0.001) in GSH concentration in whole blood relative to the initial value. The decrease lasted for 24 hours after AnEx. GSSG concentration in the blood significantly decreased 15 minutes after AnEx in both sexes. It subsequently began to increase, reaching a level significantly higher than the resting value, both after 60 minutes and 24 hours of recovery. The ratio of GSH/GSSG concentrations was significant lower than the resting value 60 minutes and 24 hours after AnEx. Vit A and TAC concentrations were significantly higher in men, while Vit C concentration was significantly higher in women. The aim of this study was to compare disruptions in men and women to the prooxidant-antioxidant balance in the blood that take place within the first hour and the 24 hours after AnEx. The study assessed oxidative stress based on analysis of changes in TOS and TAC of blood plasma, changes in the concentrations of selected low molecular weight non-enzymatic antioxidants (GSH, UA, Vit A, Vit E and Vit C), and changes in GSSG concentration. The study also assessed disruptions to the prooxidant-antioxidant balance based on the GSH/GSSG concentration ratio and the OSI. Obtained results confirm one of the two proposed hypotheses. In both sexes, anaerobic exercise was found to cause disruptions to the prooxidant-antioxidant balance in the blood that lasted up to 24 hours after the exercise. However, contrary to the other proposed hypothesis, the disruptions increased to a similar extent in both sexes. Changes in the concentrations of all oxidative stress indicators following AnEx were significant in both sexes. Apart from GSH concentration and the GSH/GSSH concentration ratio, all changes took place progressively. The analyzed biochemical indicators of oxidative stress reached maximal values at different times after AnEx. OSI, TOS, TAC and Vit A and Vit E concentrations reached a maximal value after three minutes of recovery. Vit C concentration reached a maximal value after 30 minutes of recovery and UA concentration reached a maximal value after 60 minutes of recovery. At the same time, Vitamin C concentration in the blood was significantly higher in women than in men in all measurements. This, however, did not affect the antioxidant capacity of blood plasma, which was higher in men than in women. Consequently, the higher level of vitamin C observed in women could have resulted from a higher intake of the vitamin in their diet, rather than from sex differences related to the response to AnEx [38]. A decrease in GSH concentration in the blood was observed 15 minutes after AnEx. The decrease remained at a similarly low value for the 24 hours after AnEx. Surprisingly, GSSG concentration decreased 15 minutes after AnEx and only increased at a later stage of recovery, reaching a value significantly higher than the resting value after 60 minutes of recovery. GSSG concentration still showed a significant increase 24 hours after AnEx. A decrease in the GSH/GSSG concentration ratio, observed after one hour and as much as 24 hours after recovery, indicated increasing oxidative stress following AnEx. The highest concentration of thiobarbituric acid reactive substances (oxidative stress indicator) was observed after one hour after exercise at 90%VO2max, preceded by a 45-minute submaximal exercise (70–75%VO2max) and performed until volitional exhaustion, and the greatest changes in TAC, GSH and GSSG concentrations and the GSH/GSSG concentration ratio occurred two hours after anaerobic exercise [39]. Thus, the time after which the greatest changes in individual oxidative stress indicators occur depends on the duration and intensity of exercise. The results of this study differ from those obtained in an earlier study by Karabulut [40], who compared changes in oxidative stress indicators in men and women occurring directly after anaerobic exercise, in particular, a 20-meter run at maximal speed. Karabulut [40] found an increase in malondialdehyde as a product of oxidative damage to lipids and a decrease in GSH concentration only in men, and no significant changes in the analyzed indicators in women. A study by Ilhan et al. [41], the participants of which comprised 30 men and 30 women who performed the 30-second Wingate test, found that the initial levels of lipid peroxidation products were higher in men, GSH concentration was higher in women and anaerobic exercise did not significantly affect the levels of the analyzed indicators in either of the sexes. However, neither Karabulut [40] nor Ilhan et al. [41] assessed disruptions to the acid-base balance following anaerobic exercise. A positive correlation between the post-exercise increase in TOS and the post-exercise increase in Lac concentration in the blood was found following the IT until volitional exhaustion [13]. Therefore, the level of oxidative stress (similar in both sexes) following AnEx observed in this study may have been caused by a lack of sex differences in the increase in Lac and H+ concentration after the exercise. In sum, the results obtained in this study lead to the conclusion that under similar disruptions to acid-base balance between sexes, anaerobic exercise causes the same changes in total antioxidative capacity, total oxidative status, the oxidative stress index and non-enzymatic antioxidants of low molecular weight in both sexes. Changes in GSH, GSSG and ratio of GSH/GSSG concentrations indicate that oxidative stress lasts at least 24 hours following anaerobic exercise. The interpretation of the level of disruptions to the prooxidant-antioxidant balance following AnEx should take into account the fact that post-exercise changes in oxidative stress indicators occur at different times.   Source: http://doi.org/10.1371/journal.pone.0143499