Metabolic insights at the finish line: deciphering physiological changes in ultramarathon runners through breath VOC analysis

Exhaustive exercise can induce unique physiological responses in the lungs and other parts of the human body. The volatile organic compounds (VOCs) in exhaled breath are ideal for studying the effects of exhaustive exercise on the lungs due to the proximity of the breath matrix to the respiratory tract. As breath VOCs can originate from the bloodstream, changes in abundance should also indicate broader physiological effects of exhaustive exercise on the body. Currently, there is limited published data on the effects of exhaustive exercise on breath VOCs. Breath has great potential for biomarker analysis as it can be collected non-invasively, and capture real-time metabolic changes to better understand the effects of exhaustive exercise. In this study, we collected breath samples from a small group of elite runners participating in the 2019 Ultra-Trail du Mont Blanc ultra-marathon. The final analysis included matched paired samples collected before and after the race from 24 subjects. All 48 samples were analyzed using the Breath Biopsy Platform with GC-Orbitrap™ via thermal desorption gas chromatography-mass spectrometry. The Wilcoxon signed-rank test was used to determine whether VOC abundances differed between pre- and post-race breath samples (adjustedP-value < .05). We identified a total of 793 VOCs in the breath samples of elite runners. Of these, 63 showed significant differences between pre- and post-race samples after correction for multiple testing (12 decreased, 51 increased). The specific VOCs identified suggest the involvement of fatty acid oxidation, inflammation, and possible altered gut microbiome activity in response to exhaustive exercise. This study demonstrates significant changes in VOC abundance resulting from exhaustive exercise. Further investigation of VOC changes along with other physiological measurements can help improve our understanding of the effect of exhaustive exercise on the body and subsequent differences in VOCs in exhaled breath.

Interleukin-4 during post-exercise recovery negatively correlates with the production of phagocyte-generated oxidants

Exhaustive run induced a biphasic oxidative response of circulating phagocytes in 16 amateur sportsmen. The first phase involved an increment just after exercise of enhanced whole blood chemiluminescence normalized per phagocyte count, whereas in the second phase a decrement from 1 h post-exercise and ongoing till 24 h. We tested whether plasma Interleukin IL-4, IL-8, IL-10 and Tumor Necrosis Factor α concentrations change in response to exhaustive run and whether there are associations between their levels and delta resting. Moreover, IL-8 and IL-10 significantly increased immediately post-exercise and after 1 h, but later normalized. Tumor necrosis factor α rose by 1.1-times only just after exercise. However, none of these cytokines showed any correlation with the investigated chemiluminescence. Exercise did not alter plasma concentrations of IL-4. However, pre-exercise IL-4 negatively correlated with measured luminescence just after exercise (ρ = -0.54, p < 0.05), and also tended to be negatively associated with decrements of the second phase at 1 h post-exercise ρ = -0.45, p = 0.08. It is suggested that plasma IL-4, by a negative association with blood phagocytes oxidants production, could be involved in the maintenance of proper balance between oxidants and anti-oxidants during strenuous exercise and post-exercise recovery.

Effects of Exhaustive Exercise on Inflammatory, Apoptotic, and Antioxidative Signaling Pathways in Human Peripheral Blood Mononuclear Cells

In the present study, we investigated the effects of exhaustive exercise and recovery on inflammatory, pro-apoptotic, and anti-oxidative responses in human peripheral blood mononuclear cells (PBMCs). Sixteen volunteers participated in a guided physical activity program in which they were subjected to progressive exercise on the treadmill until they were exhausted followed by an 1-hour recovery period. Isolated human PBMCs were collected before exercise, immediately after exercise, and after 1-hour recovery. Exhaustive exercise induced expression of heme oxygenase-1 and glutamate cysteine ligase catalytic subunit and activation of NF-κB and NF-E2 related factor 2 (Nrf2). Apoptosis, as measured by activity and cleavage of caspase-3 and its substrate PARP also significantly increased. However, induction of redox signaling and the pro-apoptotic response fully returned to the baseline level during the 1-hour recovery period. On the other hand, COX-2 expression was continuously elevated after exercise cessation throughout the 1-hour recovery period. Taking all these findings into account, we conclude that exhaustive exercise transiently induces Nrf2-mediated antioxidant gene expression and eliminates damaged cells through apoptosis as part of an adaptive cytoprotective response against oxidative and inflammatory stress.

The Role of Metabolic Phenotype in the Capacity to Balance Competing Energetic Demands

AbstractGiven the critical role of metabolism in the life history of all organisms, there is particular interest in understanding the relationship between individual metabolic phenotypes and the capacity to partition energy into competing life history traits. Such relationships could be predictive of individual phenotypic performances throughout life. Here, we were specifically interested in whether an individual fish's metabolic phenotype can shape its propensity to feed following a significant stressor (2-min exhaustive exercise challenge). Such a relationship would provide insight into previous intraspecific observations linking high metabolism with faster growth. Using a teleost fish, the barramundi (Lates calcarifer), we predicted that individuals with high standard metabolic rates (SMRs) and maximal metabolic rates (MMRs) would be faster to recover and resume feeding after exercise. Contrary to our prediction, neither SMR nor MMR was correlated with latency to feed after exercise (food was offered at 0.5, 1.5, 3, and 18 h after exercise). Only time after exercise and individual fish ID were significant predictors of latency to feed. Measurements of MMR from the same individuals (three measurements spaced 8-12 d apart) revealed a moderate degree of repeatability (R=0.319). We propose that interindividual differences in biochemical and endocrine processes may be more influential than whole-organism metabolic phenotype in mediating feeding latency after exercise.

Effects of 6-Week Supplementation with GliSODin on Parameters of Muscle Damages, Metabolic, and Work Performance at International Level Rowers after Specific Maximal Effort

This study aimed to investigate the effect of supplementation with plant origin superoxide dismutase (SOD), GliSODin, on parameters of muscle damage, metabolic, and work performance at international level rowers. Twenty-eight rowers were included in a randomized, double-blind study. The study was conducted during a 6-week preparation period. At the beginning of the study and after 6 weeks of the supplementation period, all rowers were tested on a rowing ergometer. Blood samples were taken from the antecubital vein before and after every ergometer testing. Muscle damage markers creatine kinase (CK) and lactate dehydrogenase (LDH), total antioxidant capacity (TAC), inflammation parameters interleukin-6 (IL-6), and C-reactive protein (CRP) were measured. Rowing performance was assessed by lactate level in capillary blood and power output on the rowing ergometer. After supplementation, experimental group had significantly lower CK (p = 0.049) and IL-6 (p = 0.035) before and IL-6 (p = 0.050) after exhausting exercise on ergometer. Relative change of power output at 4 mmol/L concentration of lactate in blood, considering the initial and final test, was significantly higher (p = 0.020) in the supplemented group. It was concluded that GliSODin could be considered a good supplement in preventing some deleterious effects of intensive physical activity, including inflammation and muscle damage, and consequently, to enable a better rowing performance of elite rowers.

[Experimental study of mitochondrion-targeted small molecule IR-61 ameliorated exhaustive exercise-induced cardiac injury in rats]

OBJECTIVE

To investigate the effects of mitochondrion-targeted cyanine fluorescent small molecule IR-61 on cardiac injury induced by exhaustive exercise in rats.

METHODS

Thirty-six adult male SD rats were randomly divided into 3 groups(n=12),control group (Ctrl), exhaustive exercise group (EE) and IR-61+ exhaustive exercise group (IR-61+EE). IR-61+EE group were intraperitoneally injected with 2 mg/kg IR-61 at the same time on day 1, 4 and 7. One hour after the end of the last drug administration, the two exhaustive exercise groups were subjected to exhaustive exercise modeling. The rats were placed on an animal treadmill with a slope of 0° at a speed of 10~15 m/min to coordinate their limbs running posture, and then ran at a speed of 25~30 m/min until exhaustion about 15 minutes later. After the animal models established, ECG was recorded by physiological recorder, myocardial injury was observed by light microscope, mitochondrial injury was observed by transmission electron microscope, myocardial cell apoptosis was detected by TUNEL method, markers of myocardial injury were detected by ELISA, and myocardial mitochondrial respiration rate was measured by high-resolution Oxygraph-2K mitochondrial instrument.

RESULTS

① Compared with Ctrl group, heart rate was increased, PR interval was shortened, QRS interval was prolonged, QTc was prolonged and ST segment was depressed significantly in EE group (P＜0.05). In EE group, myocardial fiber fracture and mitochondrial inner chamber swelling were obvious, mitochondrial crest was fuzzy, mitochondrial outer membrane was incomplete, and a large number of mitochondrial rupture and fusion were visible. In EE group, TUNEL staining cells were abundant, chromatin concentration and marginalization, nuclear membrane lysis, chromatin fragmentation into massive apoptotic bodies, apoptosis score increased (P＜0.05). The levels of creatine kinase isoenzyme-MB (CK-MB), cardiac troponin I(cTn-I) and N-terminal B-type natriuretic peptide (NT-proBNP) were increased in EE group (P＜0.05). Basal respiration rate, oxidative respiration rate of fatty acids and respiration rate of complex Ⅰ, Ⅱ and Ⅳ were all decreased (P＜ 0.05). ② Compared with EE group, the heart rate in IR-61+EE group was increased, PR interval was prolonged, QRS interval was shortened, QTc was shortened, ST segment was not significantly depressed (P＜0.05). In IR-61+EE group, myocardial fiber arrangement was loose, no obvious fracture was observed, mitochondrial inner ventricle was swelling, mitochondrial outer membrane was intact, TUNEL stained cells and unstained cells were observed, the overall morphology was more similar to Ctrl group. Apoptosis index was decreased (P＜0.05), the levels of CK-MB and cTn-I were decreased in IR-61+EE group (P＜0.05). The oxidative respiration rate of fatty acids and the respiration rate of complex Ⅱ and Ⅳ were increased (P＜0.05).

CONCLUSION

Mitochondrion-targeted cyanine fluorescent small molecule IR-61 can improve cardiac electrical activity, reduce myocardial cell injury and mitochondrial injury, reduce myocardial cell apoptosis, and improve the myocardial mitochondrial energy metabolism condition in exhausted rats.

Dihydromyricetin-Encapsulated Liposomes Inhibit Exhaustive Exercise-Induced Liver Inflammation by Orchestrating M1/M2 Macrophage Polarization

Exhaustive exercise (EE) induced hepatic inflammatory injury has been well reported. Dihydromyricetin (DHM) has shown anti-inflammatory bioactivity and hepatoprotective effects but is limited by poor bioavailability. Here, high-bioavailability DHM-encapsulated liposomes were synthesized and explored for their therapeutic potential and regulatory mechanisms in a hepatic inflammatory injury model. The animal model was established by swimming-to-exhaustive exercise in C57BL/6 mice, and the anti-inflammatory effects were detected after administration of DHM or DHM liposome. NIR fluorescence imaging was used to assess the potential of liver targeting. The DHM liposome-induced macrophage polarization was measured by flow cytometry ex vivo. The anti-inflammatory mechanism of DHM was studied in cell line RAW264.7 in vitro. Liposome encapsulation enhanced DHM bioavailability, and DHM liposome could alleviate liver inflammation more effectively. Moreover, DHM liposome targeted hepatic macrophages and polarized macrophages into an anti-inflammatory phenotype. The SIRT3/HIF-1α signaling pathway could be the major mechanism of DHM motivated macrophage polarization. Our study indicates that DHM liposomes can alleviate liver inflammation induced by EE through sustained releasing and hepatic targeting. It is a promising option to achieve the high bioavailability of DHM. Also, this study provides new insights into the regional immune effect of DHM against inflammation.

Exhaustive Exercise Increases Spontaneous but Not fMLP-Induced Production of Reactive Oxygen Species by Circulating Phagocytes in Amateur Sportsmen

Strenuous exercise alters the oxidative response of blood phagocytes to various agonists. However, little is known about spontaneous post exercise oxidant production by these cells. In this cross-over trial, we tested whether an exhaustive treadmill run at a speed corresponding to 70% of VO2max affects spontaneous and fMLP-provoked oxidant production by phagocytes in 18 amateur sportsmen. Blood was collected before, just after, and 1, 3, 5 and 24 h post exercise for determination of absolute and normalized per phagocyte count spontaneous (a-rLBCL, rLBCL) and fMLP-induced luminol-enhanced whole blood chemiluminescence (a-fMLP-LBCL, fMLP-LBCL). a-rLBCL and rLBCL increased by 2.5- and 1.5-times just after exercise (p < 0.05) and then returned to baseline or decreased by about 2-times at the remaining time-points, respectively. a-fMLP-LBCL increased 1.7- and 1.6-times just after and at 3 h post-exercise (p < 0.05), respectively, while fMLP-LBCL was suppressed by 1.5- to 2.3-times at 1, 3, 5 and 24 h post-exercise. No correlations were found between elevated post-exercise a-rLBCL, a-fMLP-LBCL and run distance to exhaustion. No changes of oxidants production were observed in the control arm (1 h resting instead of exercise). Exhaustive exercise decreased the blood phagocyte-specific oxidative response to fMLP while increasing transiently spontaneous oxidant generation, which could be a factor inducing secondary rise in antioxidant enzymes activity.

Mechanical, Cardiorespiratory, and Muscular Oxygenation Responses to Sprint Interval Exercises Under Different Hypoxic Conditions in Healthy Moderately Trained Men

Objective: The aim of this study was to determine the effects of sprint interval exercises (SIT) conducted under different conditions (hypoxia and blood flow restriction [BFR]) on mechanical, cardiorespiratory, and muscular O₂ extraction responses.

Methods: For this purpose, 13 healthy moderately trained men completed five bouts of 30 s all-out exercises interspaced by 4 min resting periods with lower limb bilateral BFR at 60% of the femoral artery occlusive pressure (BFR₆₀) during the first 2 min of recovery, with gravity-induced BFR (pedaling in supine position; G-BFR), in a hypoxic chamber (FiO₂≈13%; HYP) or without additional stress (NOR). Peak and average power, time to achieve peak power, rating of perceived exertion (RPE), and a fatigue index (FI) were analyzed. Gas exchanges and muscular oxygenation were measured by metabolic cart and NIRS, respectively. Heart rate (HR) and peripheral oxygen saturation (SpO₂) were continuously recorded.

Results: Regarding mechanical responses, peak and average power decreased after each sprint (p < 0.001) excepting between sprints four and five. Time to reach peak power increased between the three first sprints and sprint number five (p < 0.001). RPE increased throughout the exercises (p < 0.001). Of note, peak and average power, time to achieve peak power and RPE were lower in G-BFR (p < 0.001). Results also showed that SpO₂ decreased in the last sprints for all the conditions and was lower for HYP (p < 0.001). In addition, Δ[O₂Hb] increased in the last two sprints (p < 0.001). Concerning cardiorespiratory parameters, BFR₆₀ application induced a decrease in gas exchange rates, which increased after its release compared to the other conditions (p < 0.001). Moreover, muscle blood concentration was higher for BFR₆₀ (p < 0.001). Importantly, average and peak oxygen consumption and muscular oxyhemoglobin availability during sprints decreased for HYP (p < 0.001). Finally, the tissue saturation index was lower in G-BFR.

Conclusions: Thus, SIT associated with G-BFR displayed lower mechanical, cardiorespiratory responses, and skeletal muscle oxygenation than the other conditions. Exercise with BFR₆₀ promotes higher blood accumulation within working muscles, suggesting that BFR₆₀ may additionally affect cellular stress. In addition, HYP and G-BFR induced local hypoxia with higher levels for G-BFR when considering both exercise bouts and recovery periods.

Melatonin improves the antioxidant capacity in cardiac tissue of Wistar rats after exhaustive exercise

We investigated the effects of melatonin on the onset and resolution of the oxidative stress in the cardiac muscle in melatonin-treated and nontreated rats subjected to an exhaustive exercise session. Forty male rats were divided into: melatonin-treated (20 mg/kg supplemented for 10 d) and control. On the 10th day, each group was subdivided according to euthanasia moments: control or melatonin-treated not exercised (C0h and M0h); immediately after the exercise (CIA and MIA); and 2 h after exercise (C2h and M2h). The heart of animals was removed and the levels of oxidative stress index (OSI) and the formation of thiobarbituric acid reactive substances (TBARS), protein carbonyl, and the activities of aconitase, catalase (CAT), glutathione peroxidase (GPx), and superoxide dismutase (SOD) were evaluated. Total antioxidant status (TAS), total oxidant status (TOS), and the protein expression of CAT, GPx, and SOD was also measured. Our data revealed significant differences on: (i) OSI (p=.029), CAT activity (p=.016), CAT content (p<.001), GPx content (p=.014), reduced glutathione levels (p<.001), and aconitase activity (p<.001) for interaction of melatonin; (ii) GPx activity (p=.005), reduced glutathione (p=.004), protein carbonyl (p=.035), and TBARS levels (p=.028) between groups, and (iii) TBARS levels (p=.016) for significance between moments. Although the exhaustive exercise protocol imposed mild oxidative stress on the cardiac tissue of rats, melatonin induced antioxidant responses that rebalanced the redox status of the cardiac tissue, especially after exhaustive exercise.

The Effects of L-Citrulline on Blood-Lactate Removal Kinetics Following Maximal-Effort Exercise

The accumulation of lactate in muscle and blood during high-intensity exercise is negatively correlated with the duration exercise can be sustained. Removal of lactate is a key component of acute recovery between consecutive bouts of such exercise. Low-intensity exercise enhances recovery by accelerating lactate turnover in metabolically active tissues, largely mediated by blood flow to these tissues. Therefore, the purpose of this research was to clarify if L-citrulline, a nutritional supplement purported to promote vasodilation via enhanced nitric oxide availability, would augment the removal of blood lactate during active recovery (AR). L-citrulline ingestion will augment the rate of blood lactate concentration decrease during AR, reduce the oxygen-cost of submaximal exercise, and increase time-to-exhaustion and peak oxygen uptake (V̇O2peak) during a test of maximal aerobic power. Healthy university students (five males & five females) participated in this double-blind, randomized, placebo-controlled study. Participants exercised on a cycle ergometer at submaximal steady-state intensities followed by progressively increasing intensity to exhaustion, 10 min of AR, and then supramaximal intensity exercise to exhaustion. Oxygen uptake was measured throughout the trial and blood lactate was sampled repeatedly during AR. The protocol elicited very high peak blood lactate concentrations after exercise (11.3 + 1.3 mmol/L). L-citrulline supplementation did not significantly alter blood lactate kinetics during AR, the oxygen cost of exercise, V̇O2peak, or time-to-exhaustion. Despite a strong theoretical basis by which L-citrulline could augment lactate removal from the blood, L-citrulline supplementation showed no effect as an exercise-recovery supplement.

Effects of General Fatigue Induced by Exhaustive Exercise on Posture and Gait Stability of Healthy Young Men

Bipedal walking is a composite task requiring integration of many control circuitries in the brain and spinal cord. The present study was carried out to verify whether an increase in blood lactate, such as that associated with a high intensity exercise, is able to significantly modify the qualitative and/or quantitative aspects of human walking. Eighteen healthy physically male participants, aged between 20 and 24 years (M = 21.8, SD = 1.22), were recruited for the study. For this purpose, the experimental protocol included the measure of blood lactate levels with the aim of assessing possible relations between lactate blood values and different aspect of walking after an exhaustive exercise. An exhaustive exercise was associated with a strong increase of blood lactate levels and produced a significant worsening in the ability to maintain the bipodalic upright posture as well as the fluidity of walking. Our results suggest that exhausting bouts impose greater challenges on postural control.

Study on the time-effectiveness of exercise preconditioning on heart protection in exhausted rats

To investigate the persistence time and the effectiveness of exercise preconditioning (EP) on myocardial protection in exhausted rats from myocardial enzymes, electrocardiogram (ECG), cardiac function, and mitochondrial respiratory function after cessation of exercise training. One hundred and twelve healthy male Sprague-Dawley rats were randomly divided into seven groups (n = 16): control group (CON), exhaustive exercise (EE) group, EP group, and EE after EP (EP + EE); furthermore, EP + EE group was randomly divided into 1D, 3D, 9D, and 18D groups (1D, 3D, 9D, and 18D) and performed exhaustive treadmill exercise at a speed of 30 m/min on the 1^st, 3^rd, 9^th, and 18^th days separately after EP exercise stopped. We detected the serum contents of N-terminal pro B type natriuretic peptide (NT-proBNP) and cardiac troponin I (cTnI) by the enzyme-linked immunosorbent assays method, recorded ECG, detected heart function by pressure volume catheter, measured the respiratory rates of rat myocardial mitochondria state 3 and 4 of complex I, complex II, and IV by high-resolution breathing apparatus. EP could decrease the serum content of NT-proBNP and cTnI, improved the electrical derangement and the left ventricular function in exhausted rats. Moreover, the protective effect was more obvious in the 9^th day after EP stopped, whereas it would disappear when EP stopped for more than 18 days. Compared with EE group, the respiratory rate value of myocardial mitochondrial complex increased in 1D, 3D, and 9D groups. Therefore, the protective effect of EP on the heart of exhausted rats decreased with the prolongation of stopping training time, and the effect was significant within 3 days of discontinuing training, then decreased gradually, and completely disappeared in the 18^th day. EP enhanced the cardiac function in exhausted rats through raising the nicotinamide adenine diphosphate hydride (NADH) electron transport chain and increased the respiration rates of mitochondrial respiratory complex I and IV state 3, thereby improved myocardial mitochondrial respiratory function and energy metabolism.

Anti-fatigue Effects of Santé Premium Silver Perch Essence on Exhaustive Swimming Exercise Performance in Rats

Aim: Fish soup is a traditional Chinese food usually offered as a healthy supplement to elders, pregnant women and persons who just had surgery. Silver perch (Santé premium silver perch essence, SPSPE) extract contains various quality proteins, collagen, minerals, trace elements, and branch chain amino acids (BCAA) that could help individuals recover from exhaustion and control body weight. However, there are very limited studies exploring the effects of fish extracts on exercise performance and fatigue, and relevant physiological mechanisms. Therefore, the purpose of this study was to investigate the effects of chronic SPSPE administration on exhaustive exercise performance.

Method: Male Wistar rats weighing around 250 g were divided into 4 groups: Control, 1X SPSPE (6.2 ml/kg), 2X SPSPE (12.4 ml/kg) and 5X SPSPE (31.0 ml/kg). Rats were administrated SPSPE by oral gavage feeding every day for 33 days. Their body weight were measured every week. Before and after the exhaustive swimming test, the blood was collected for circulating lactate, glucose, ammonia, hormones, and myoglobin analysis. Rats were sacrificed after performing an exhaustive swimming exercise test. The liver tissues were collected for glycogen content and H&E staining.

Results: After the administration of 1X and 5X SPSPE, swimming fatigue was significantly delayed (p = 0.024). There was no difference in the hormone plasma level between the control and SPSPE groups. The induction of plasma corticosterone and TBARS by exhaustive swimming exercise could be decreased by SPSPE administration. The increased plasma myoglobin concentration from exhaustive swimming exercise was weakened by SPSPE supplementation. The higher glycogen sparing contained in liver tissue was observed in SPSPE-treated groups (p < 0.05).

Conclusion: SPSPE could efficiently delay swimming fatigue through sparing of liver glycogen and attenuation of plasma TBARS, myoglobin induction by exhaustive exercise. Our findings provide a scientific-based fundamental information and better understanding for developing a fish extract-based anti-fatigue supplement.

The Effect of Acute Intense Exercise on Activity of Antioxidant Enzymes in Smokers and Non-Smokers

Acute intense exercise causes significant oxidative stress and consequently an increase in total antioxidant capacity; however, the mechanisms and combined effects of intense exercise and smoking on oxidative stress among active and non-active smokers are not clear. The aim of this study was to investigate the effect of acute intense exercise on antioxidant enzyme activity responses in active and non-active individuals exposed to cigarette smoke. The study included 40 subjects who were equally classified as: smokers that did exercise (SE), smokers that did not do exercise (SnE), non-smokers that did exercise (NSE), and non-smokers that did not do exercise (NSnE). The adjusted Astrand test was used to exhaust the subjects. Salivary enzymes of peroxidase (POX), catalase (CAT), and superoxide dismutase (SOD) were measured, by spectrophotometry methods, at 3 different time points: pre-test (TP1), post-test (TP2), and one hour after finishing the test (TP3). Significant (p < 0.05) group x time interactions were found for the three enzymes. Salivary POX, CAT and SOD increased in all groups from TP1 to TP2 and decreased from TP2 to TP3. Only the NSE showed a significant difference between TP1 to TP3 in POX and SOD by +0.011 ± 0.007 and +0.075 ± 0.020 (U/mL), respectively. The NSE showed significantly higher activity of POX, CAT and SOD in TP2 compared to the other groups. Furthermore, NSE and NSnE had higher activity of POX, CAT and SOD in TP1 and TP3 (p < 0.05) compared with SE and SnE. Only in the NSnE, were no differences observed in CAT compared with SE and SnE in TP3. These results showed that the antioxidant activity at rest and in the recovery time after the acute intense exercise was lower in SE and SnE compared with NSE and NSnE, suggesting that smoking habit may reduce the ameliorating effect of regular physical activity on acute exercise-induced oxidative stress.

Paraoxonase and oxidative stress changes in left and right ventricles of exhaustively exercised rats

Exhaustive exercise can cause subclinical inflammation to the heart, as it is an oxidative tissue that works continuously. The effect of exhaustive exercise on left and right ventricles (LVs, RVs) may be different. It is claimed that paraoxonase-1 (PON1), an antioxidant enzyme, has a cardioprotective effect on oxidative stress. Rats were separated as non-exercised controls (Con), those euthanized immediately after (E-0) and 24 h after exhaustive exercise (E-24). Cardiac troponin-I (cTnI), total antioxidant status (TAS), total oxidant status (TOS), PON1 activities, and histological findings in LV and RV of the exhausted rats were evaluated. TAS and PON1 levels were lower in LVs compared with RVs of all groups. TOS levels were high in LVs compared with RVs of all groups. In LVs, TAS levels decreased significantly in the E-0 group while PON1 activity decreased in E-0 and E-24 groups compared with controls. In LVs, TOS levels decreased significantly in E-0 and E-24 groups, but in RVs a decrease was seen only in the E-0 group. cTnI levels increased significantly in the E-0 group and decreased to control levels in the E-24 group. Considering the histological and biochemical findings, exhaustive exercise affected the heart to the maximum during and just after exhaustion, and LV was influenced more than RV.

Recovery of Diabetic Rats After Physical Exhaustion: Kinetic Alterations in Muscle Inflammation and Muscle-Signaling Proteins to Atrophy and Hypertrophy

The complexity of the adaptive response of diabetics to intense exercise is still poorly understood. To optimize exercise interventions in diabetics, the chronology of inflammatory mediators in muscle and the signaling involved in muscle hypertrophy/atrophy must be understood. Herein, we studied the kinetic inflammatory profile and cellular signaling pathways modulated by physical exhaustion after the induction of type 1 diabetes by streptozotocin in rats. Soleus muscle samples were obtained from diabetic and control groups at the following moments: baseline (no exercise); immediately after exhaustive exercise; and at 2 h, 24 h, 48 h, and 72 h after a treadmill exhaustive exercise. Kinetic production of cytokines and kinetic activation of proteins related to muscle synthesis (p70S6K and Akt) and degradation (GSK3, MuRF1, and MAFbx) were measured in the soleus muscle. We observed that the muscle TNF-α (0.9-fold; p = 0.0007), IL-1β (0.8-fold; p = 0.01), IL-6 (0.8-fold; p = 0.0013), L-selectin (1.0-fold; p = 0.0019), and CINC-2α/β (0.9-fold; p = 0.04) levels were higher in almost all stages of the study in the diabetic animals compared with the control group. Our data showed that exhaustive exercise decreased MAFbx expression in diabetic animals compared to the control group in a time-dependent manner. The decreased activation ratios of MAFbx were followed by a decrease in TNF-α, IL-1β, and IL-6 levels. p70S6k phosphorylation was also decreased in the diabetic group compared to the control group after physical exhaustion. Regarding the activation of proteins related to muscle synthesis and degradation, we found that the alterations induced by exhaustive exercise in the diabetic rats might involve pathways related to synthesis and muscle breakdown. Moreover, after an exhaustive exercise session, the recovery of the inflammatory response in the diabetic animals was slower than that in the control rats while the return of inflammatory cytokines to baseline levels was more effective in the diabetic animals.

Repetitive Bouts of Exhaustive Exercise Induces a Systemic Inflammatory Response and Multi-Organ Damage in Rats

Multiple organ dysfunction syndrome can follow severe infection or injury, but its relationship to exercise is not well understood. Previous studies have observed that prolonged strenuous exercise can lead to transiently increased level and/or activity of markers for systemic inflammatory response and multiple organ damage. However, few studies have analyzed the pathogenesis of the inflammatory response and subsequent multi-organ injury in exhaustive exercise conditions. In this study, we established a rat model of repetitive bouts of exhaustive running (RBER) and investigated its effects on multiple organ damage. Rats were subjected to RBER in either uphill or downhill running modes daily for a period of 7 days. Morphologically, RBER causes tissue structural destruction and infiltration of inflammatory cells in the skeletal muscles and many visceral organs. RBER also causes sustained quantitative changes in leukocytes, erythrocytes, and platelets, and changes in the concentration of blood inflammatory factors. These inflammatory alterations are accompanied by increases in serum enzyme levels/activities which serve as functional markers of organ damage. In general, RBER in the downhill mode seemed to cause more damage evaluated by the above-mentioned measures than that produced in the uphill mode. A period of rest could recover some degree of damage, especially for organs such as the heart and kidneys with strong compensatory capacities. Together, our data suggest that, as a result of multi-organ interactions, RBER could cause a sustained inflammatory response for at least 24 h, resulting in tissue lesion and ultimately multiple organ dysfunction.

Aralia continentalis kitagawa Extract Attenuates the Fatigue Induced by Exhaustive Exercise through Inhibition of Oxidative Stress

The present study aimed to evaluate the anti-fatigue effects of Aralia continentalis kitagawa (AC) extract during exhaustive exercise of rats by forced swimming. Rats were subjected to forced swimming until exhausted after pre-treatment with AC extract for 21 days. Exhaustion time significantly increased in rats treated with AC extract. AC treatment also preserved blood homeostasis during fatigue due to exhaustive exercise. For fatigue-related serum biomarkers, AC extract significantly fail to decrease glucose and triglyceride (TG), but ameliorated increased lactate levels compared with levels in control rats. Metabolic acidosis, a major cause of fatigue, was effectively attenuated by AC extract, according to metabolic acidosis-related blood parameters. AC extract suppressed muscle injury and attenuated gastrocnemius muscle apoptotic responses due to exhaustive exercise. To investigate the mechanisms behind the AC extract anti-fatigue effect, we evaluated its effect on oxidative stress-related fatigue. We showed that pro-oxidants were inhibited, while antioxidants were preserved by AC extract treatment. Therefore, the anti-fatigue effect of AC extract was mediated by suppression of oxidative stress. Overall, the study demonstrated that AC extract effectively attenuates fatigue from exhaustive exercise through oxidative stress inhibition. AC extract, as an antioxidant, could be utilized as a therapeutic or preventive strategy against exhaustive exercise fatigue.

Effects of Mongolian Warm Acupuncture on iNOS/NO and Inflammatory Cytokines in the Hippocampus of Chronic Fatigue Rats

The inducible nitric oxide synthase/nitric oxide (iNOS/NO) signaling pathway and inflammatory cytokines play important roles in the pathogenesis of exercise-induced fatigue. Studies have found that Mongolian warm acupuncture (WA) could alleviate exercise-induced fatigue. However, the exact mechanisms underlying its effects remain unclear. In the present study, we investigated the effects of Mongolian WA on iNOS/NO signaling pathway and proinflammatory cytokines in a chronic exhaustive swimming-induced fatigue rat model. Animals were randomly divided into Control group, Ctrl + WA group, Model group, and Model + WA group. The body weight, exhaustive swimming time test, and Morris water maze test were performed before and after the chronic exhaustive swimming. The serum levels of interleukin-1β (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and iNOS were detected by enzyme linked immunosorbent assay (ELISA). The mRNA expressions of IL-1β, IL-6, TNF-α, IFN-γ, and iNOS in the hippocampus were measured by real-time polymerase chain reaction (RT-PCR). Moreover, the protein expression of iNOS in the hippocampus was measured by western blot, and the NO productions in the serum and hippocampus were detected by Griess reaction system. Chronic exhaustive exercise significantly reduced the body weight and exhaustive swimming time, and induced impairment in learning and memory, and which were reversed by WA treatment. Chronic exhaustive exercise also increased the expressions of iNOS and proinflammatory cytokines, while WA treatment significantly decreased the level of iNOS and proinflammatory cytokines. However, chronic exhaustive exercise did not affect the NO production. These findings demonstrated that WA could alleviate the chronic exhaustive swimming-induced fatigue and improve the learning and memory ability, and the actions might be related to the reduction of inflammatory response and iNOS expression.

Effects of a Bout of Intense Exercise on Some Executive Functions

The present study examined the effects of an exhaustive exercise on executive functions by using the Stroop Color Word Test (SCWT), Trail Making Test (TMT), A and B, and simple Reaction Time (RT). Thirty adults agreed to participate; 15 participants had a mean age of 24.7 years ± 3.2 Standard Deviation (SD, Standard Deviation) (group YOUNG), while the remaining 15 had a mean age of 58.9 years ± 2.6 SD (group OLD). Each subject performed the cognitive tasks at rest and blood lactate was measured (pre); each subject executed the acute exhaustive exercise and, immediately after the conclusion, executed the cognitive tasks and blood lactate was again measured (end). Cognitive tests were repeated and blood lactate measured 15 min after its conclusion of the exhaustive exercise (post). We observed: (1) a significant positive correlation between blood lactate levels and RT levels; (2) a significant negative relationship between levels of blood lactate and the SCWT mean score; (3) no significant correlation between blood lactate levels and TMT scores (time and errors), both A and B; (4) variations in blood lactate levels, due to exhaustive exercise, and parallel deterioration in the execution of RT and SCWT are significantly more pronounced in the group YOUNG than in the group OLD. The present study supports the possibility that high levels of blood lactate induced by an exhaustive exercise could adversely affect the executive functions pertaining to the prefrontal cortex.

Effect of Acacia Polyphenol Supplementation on Exercise-Induced Oxidative Stress in Mice Liver and Skeletal Muscle

The purpose of this study was to investigate the effects of acacia polyphenol (AP) supplementation on exercise-induced oxidative stress in mouse liver and skeletal muscle. Plasma aspartate aminotransferase (AST), liver and skeletal muscle levels of thiobarbituric acid reactive substance (TBARS), and levels of skeletal muscle protein carbonyls increased immediately after exhaustive exercise. Exhaustive exercise also decreased liver glutathione (GSH). These results suggest that the exhaustive exercise used in this study induced tissue damage and oxidative stress. Contrary to our expectations, AP supplementation increased plasma AST and alanine aminotransferase activities, liver levels of TBARS, and protein carbonyls. Furthermore, AP supplementation decreased glutathione and glutathione peroxidase activity in the liver. On the other hand, AP supplementation decreased TBARS levels in skeletal muscle. These results suggest that oral high-dose AP administration decreased oxidative stress in skeletal muscle but induced oxidative stress in the liver and increased hepatotoxicity.

The Effect of Glutamine Supplementation on Oxidative Stress and Matrix Metalloproteinase 2 and 9 After Exhaustive Exercise

Background

Glutamine is the most abundant amino acid in plasma and skeletal muscles and an important fuel for immune system cells. It has beneficial anti-inflammatory and antioxidant properties which may be considered as a potentially useful supplement for athletes. The present study was conducted to investigate the effect of glutamine supplementation on oxidative stress and matrix metalloproteinase 2 and 9 after exhaustive exercise in young healthy males.

Materials and methods

In this study, 30 healthy males (supplement =15 and control=15) were randomly assigned into two groups. The supplement group received 0.3 g/kg BW of glutamine along with 25 gr of sugar dissolved in 250 cc water per day. The control group received 25 gr of sugar in 250 cc water per day. Fasting blood samples were taken at baseline and at the end of 14 days of intervention. The participants underwent exercise until experiencing full-body exhaustive fatigue for 16 ± 2.84 mins, and then fasting blood samples were taken. Serum levels of TAC, MDA, MMP2, MMP9, glutathione, and hs-CRP were measured.

Results

Serum levels of MDA and hs-CRP significantly decreased in the supplement group (p< 0.05). The serum level of TAC significantly increased in the supplement group (p< 0.05). Glutathione serum levels significantly increased after exhaustive exercise (p< 0.05). Serum levels of MMP2 and MMP9 remained unchanged.

Conclusion

Results of this study showed that, some biochemical factors are time-dependent and can increase or decrease over time, as well as, serum levels of hs-CRP and MDA decreased with glutamine supplementation along with the increase in the TAC serum levels, but this supplementation had no effect on serum levels of MMP2 and MMP9 in exhaustive exercise.

α-Klotho Expression in Mouse Tissues Following Acute Exhaustive Exercise

α-Klotho, a multifunctional protein, has been demonstrated to protect tissues from injury via anti-oxidation and anti-inflammatory effects. The expression of α-klotho is regulated by several physiological and pathological factors, including acute inflammatory stress, oxidative stress, hypertension, and chronic renal failure. Exhaustive exercise has been reported to result in tissue damage, which is induced by inflammation, oxidative stress, and energy metabolism disturbance. However, little is known about the effects of exhaustive exercise on the expression of α-klotho in various tissues. To determine the effects, the treadmill exhaustion test in mice was performed and the mice were sacrificed at different time points following exhaustive exercise. Our results confirmed that the full-length (130 kDa) and shorter-form (65 kDa) α-klotho were primarily expressed in the kidneys. Moreover, we found that, except for the kidneys and brain, other tissues primarily expressed the shorter-form α-klotho, including liver, which was in contrast to previous reports. Furthermore, the shorter-form α-klotho was decreased immediately following the acute exhaustive exercise and was then restored to the pre-exercise level or even higher levels in the next few days. Our results indicate that α-klotho may play a key role in the body exhaustion and recovery following exhaustive exercise.

Sparassis crispa Intake Improves the Reduced Lipopolysaccharide-Induced TNF-α Production That Occurs upon Exhaustive Exercise in Mice

Our previous study showed that lipopolysaccharide (LPS)-induced tumor necrosis factor (TNF)-α production is inhibited by acute exhaustive exercise in mice, leading to transient immunodepression after exercise. Sparassis crispa (SC), an edible mushroom, has immunopotentiative properties. This study aimed to clarify the effects of SC intake on reduced LPS-induced TNF-α production upon exhaustive exercise in mice. Male C3H/HeN mice were randomly divided into three groups: normal chow intake + resting sedentary, normal chow intake + acute exhaustive treadmill running exercise, and SC intake (chow containing 5% SC powder for 8 weeks) + the exhaustive exercise groups. Each group was injected with LPS immediately after the exhaustive exercise or rest. Plasma and tissue TNF-α levels were significantly decreased by exhaustive exercise. However, this reduction of the TNF-α level was partially attenuated in the plasma and small intestine by SC intake. Although levels of TLR4 and MyD88 protein expression were significantly decreased in tissues by exhaustive exercise, the reduction of TLR4 and MyD88 levels in the small intestine was partially attenuated by SC intake. These results suggest that SC intake attenuates exhaustive exercise-induced reduction of TNF-α production via the retention of TLR4 and MyD88 expression in the small intestine.

Metabonomic Analysis of the Therapeutic Effects of Chinese Medicine Sanqi Oral Solution on Rats With Exhaustive Exercise

Exhaustive exercise has emerged as an important health issue nowadays. This study was designed to assess the metabolite abnormalities of rats after exhaustive exercise and the holistic efficacy of Chinese medicine Sanqi oral solution (SQ). Through exhaustive swimming, the exhaustive exercise model in rats was established. Thirty male Sprague–Dawley rats were randomly divided into control, model, and treatment groups. SQ (12 mL·kg⁻¹·d⁻¹) or 0.9% saline solution was administrated orally by gastric gavage. After 4 weeks, serum samples were collected for biochemical measurements and ultra performance liquid chromatography (UPLC)/quadrupole time-of-flight mass spectrometry (Q-TOF-MS)-based metabonomic study. It was found that rats with SQ intervention showed longer exhaustive swimming time (P < 0.05) than model rats, with an average of 1,160.36 ± 123.89 s in SQ group and 906.57 ± 172.11 s in model group. Among the biochemical indices, the levels of creatine kinase isoenzyme, lactate dehydrogenase, and glucose of exhaustive exercise rats increased, whereas levels of creatine kinase, urea, triglyceride, and total cholesterol decreased. These biochemical indices came normal after SQ administration, except for triglyceride. Twenty-seven potential biomarkers belonging to sphingolipids, phospholipids, fatty acids, amino acid, and other classes were identified in serum. This study indicated that SQ exerted protective effects on exhaustive exercise by significantly prolonging the swimming endurance time. The metabonomic-based findings of the metabolic state and analysis of potential biomarkers in serum well correlated with biochemical assessment, confirming that SQ had a definite efficacy. Moreover, the shifts in lipid-related metabolites and glycolytic pathway suggested that SQ may serve as a potential supplementation in sports nutrition for its pharmacological effect of regulating energy metabolism as well as improving signal transduction and muscle-cell physiological functions.

Lactic Acid Accumulation During Exhaustive Exercise Impairs Release of Neutrophil Extracellular Traps in Mice

Lactic acid (LA) is a sensitive indicator of exercise intensity and duration. A single bout of prolonged and intensive exercise can cause transient immunosuppression through the interaction of cellular, humoral, and hormone factors. Exercise-induced influences on neutrophil extracellular traps (NETs) release have been reported, but the underlying mechanism is unknown. This study investigated NETs release, cell-free DNA (cf-DNA), and LA concentration in mice after 60 and 145 min of intensive, graded treadmill running. The concentration of LA and cf-DNA increased, while the level of myeloperoxidase-DNA (MPO-DNA) (an indicator of NETs release) decreased during 145 min of exhaustive running. LA was positively and negatively correlated with cf-DNA and MPO-DNA (R 2 = 0.57 and 0.53, respectively, both p < 0.001). Subsequent in vitro experiments were conducted with neutrophils activated by phorbol myristate acetate (PMA) in the presence of LA at different concentrations. Increasing LA concentrations were associated with decreases in NETs release and reactive oxygen species (ROS) formation. Taken together, this work furthers our understanding of how NETs and oxidative reaction respond to one bout of prolonged and intensive running. The data support a negative relationship between LA accumulation and NETs release after heavy exertion.

Evaluation of the Heart Function of Swimmers Subjected to Exhaustive Repetitive Endurance Efforts During a 500-km Relay

Aim: Knowledge of the human body's ability to adapt to repeated endurance efforts during swimming is limited. We echocardiographically assessed the impact of an exhausting and repetitive swimming effort on cardiac activity. Materials: Fourteen well-trained amateur swimmers (8 female swimmers aged 16-43 years and 6 male swimmers aged 13-67 years old) participated in an ultramarathon relay. Over 5 days, swimmers swam 500 km in the Warta River (in 5-km intervals). Each swimmer swam seven intervals, each within 44:46 to 60:02 min. Objective difficulties included low water temperatures, strong winds, rain, and night conditions. Methods: Transthoracic echocardiography (TTE) was performed three times: at baseline (the day before exertion), at peak effort, and during recovery (48 h after the event). The heart rate (HR) of each swimmer was monitored. Results: Swimmers completed the ultramarathon relay within approximately 91 h. The average HR value at the end of each interval was 91% HRmax. TTE test results showed no significant changes indicative of deterioration of myocardial function at peak effort or after 48 h. Significant increases in left ventricular (LV) ejection fraction, LV fractional shortening (LVFS), LV myocardial systolic velocity, and right ventricular (RV) fractional area changes observed on day 2 after swimming were compared to baseline values and peak effort values. No significant changes in diastolic heart function were observed. Conclusion: Echocardiography assessment indicated that prolonged intense swimming does not affect LV or RV function. Supercompensation of the post-event RV function and increased global LV systolic function demonstrated ventricular interaction after prolonged intense swimming.

Trimetazidine Attenuates Exhaustive Exercise-Induced Myocardial Injury in Rats via Regulation of the Nrf2/NF-κB Signaling Pathway

Exhausted exercise has been reported to cause the damage of myocardial structure and function in terms of cardiomyocyte apoptosis, oxidative stress, and energy metabolism disturbance. Trimetazidine (TMZ), as an anti-ischemic agent, has been approved to be effective in promoting myocardial energy metabolism, anti-inflammatory, and anti-oxidation. However, few studies examined the effects of TMZ on myocardial injury induced by exhausted exercise. To investigate whether TMZ could ameliorate the exhaustive exercise-induced myocardial injury and explore the underlying mechanisms, here the rat model of exhaustive exercise was induced by prolonged swimming exercise and TMZ was administrated to rats before exhaustive exercise. According to the results, we demonstrated that exhaustive exercise led to cardiomyocyte damage in rats as evidenced by elevations in cTnI and NT-proBNP levels, and decrease in CX43 expression, which was attenuated by TMZ treatment. Moreover, the administration of TMZ was found to restrain exhaustive exercise-induced oxidative stress damage by increasing GSH level, SOD and GSH-Px activities, and decreasing MDA level. Additionally, TMZ ameliorated myocardial injury by inhibiting apoptosis via reducing Bax/Bcl-2 ratio and down-regulating cleaved caspase-3, cleaved PARP, and cytochrome c levels in the myocardium of rats. Furthermore, we found that TMZ suppressed oxidative stress and cardiomyocyte apoptosis via activation of Nrf2/HO-1 and inactivation of NF-κB signaling pathways. Therefore, our study suggested that TMZ provided cardioprotection in rats after exhaustive exercise, indicating TMZ might served as a potential therapeutic drug for exhaustive exercise-induced myocardial injury.

TIGAR regulates mitochondrial functions through SIRT1-PGC1α pathway and translocation of TIGAR into mitochondria in skeletal muscle

TP53-induced glycolysis and apoptosis regulator (TIGAR), a glycolytic inhibitor, plays vital roles in regulating cellular metabolism and oxidative stress. However, the role of highly expressed TIGAR in skeletal muscle remains unexplored. In the present study, TIGAR levels varied in different skeletal muscles and fibers. An exhaustive swimming test with a load corresponding to 5% of body weight was utilized in mice to assess the effects of TIGAR on exercise-induced fatigue and muscle damage. The running time and metabolic indicators were significantly greater in wild-type (WT) mice compared with TIGAR knockout (KO) mice. Poor exercise capacity was accompanied by decreased type IIA fibers in TIGAR KO mice. Decreased mitochondrial number and mitochondrial oxidative phosphorylation were observed more in TIGAR KO mice than in WT mice, which were involved in sirtuin 1 (SIRT1)-mediated deacetylation of peroxisome proliferator-activated receptor γ coactivator 1α (PGC1α), and resveratrol treatment in TIGAR KO mice can increase mitochondrial content and exercise time. Much more TIGAR was also detected in mitochondria during exhaustive exercise. In addition, TIGAR, rather than mitochondria-targeted TIGAR achieved by in vitro plasmid transfection, promoted SIRT1-PGC1α pathway. Glutathione S-transferase-TIGAR pull-down assay followed by liquid chromatography mass spectrometry found that TIGAR interacted with ATP synthase F1 subunit α (ATP5A1), and its binding to ATP5A1 increased during exhaustive exercise. Overexpression of mitochondrial-TIGAR enhanced ATP generation, maintained mitochondrial membrane potential and reduced mitochondrial oxidative stress under hypoxia condition. Taken together, our results uncovered a novel role for TIGAR in mitochondrial regulation in fast-twitch oxidative skeletal muscle through SIRT1-PGC1α and translocation into mitochondria, which contribute to the increase in exercise endurance of mice.-Geng, J., Wei, M., Yuan, X., Liu, Z., Wang, X., Zhang, D., Luo, L., Wu, J., Guo, W., Qin, Z.-H. TIGAR regulates mitochondrial functions through SIRT1-PGC1α pathway and translocation of TIGAR into mitochondria in skeletal muscle.

Grape seed proanthocyanidin extract supplementation affects exhaustive exercise-induced fatigue in mice

Background

Grape seed proanthocyanidin extract (GSPE) has been extensively reported to possess a wide range of beneficial properties in multiple tissue damage. Previous studies have shown that exhaustive exercise-induced fatigue associates with oxidative stress injury, inflammatory response, and mitochondrial dysfunction.

Objective

The aim of this study is to investigate the anti-fatigue effects of GSPE in mice and explore its possible underlying mechanism.

Design

The mouse model of exhaustive exercise-induced fatigue was established by using the forced swimming test, and GSPE was orally treated for successive 28 days at 0, 1, 50 and 100 mg/kg/day of body weight, designated the control, GSPE-L, GSPE-M and GSPE-H groups, respectively.

Results

The presented results showed that treatment of GSPE at a dose of 50 and 100 mg/kg/day of body weight significantly relieved exhaustive exercise-induced fatigue, indicated by increasing the forced swimming time. In addition, treatment of GSPE significantly improved the creatine phosphokinase and lactic dehydrogenase, as well as lactic acid level in exhaustive swimming. For underlying mechanisms, treatment of GSPE had anti-fatigue effects by promoting antioxidant ability and resisting oxidative effect, as represented by increased total antioxidative capability levels, enhanced superoxide dismutase and catalase activities, and ameliorated malondialdehyde levels. Furthermore, treatment of GSPE significantly inhibited the activity of tumor necrosis factor-α and interleukin-1β, which suggested that its protective effects on exhaustive exercise-induced fatigue may be attributed to inhibition of inflammatory response. Last but not the least, treatment of GSPE significantly improved succinate dehydrogenase and Na+-K+-ATPase levels to enhance mitochondrial function during exhaustive swimming-induced fatigue.

Conclusions

These results proved that treatment of GSPE possessed the beneficial properties of anti-inflammatory, antioxidant, and mitochondrial protection to improve exhaustive exercise, which suggested that GSPE could be used as an effective functional food to delay fatigue.

Interleukin-6 and hepcidin expression changes in cardiac tissue of long-term trained and untrained rats after exhaustive exercise

Background/aim: Exercise benefits the cardiovascular system, but strenuous exercise can cause cardiac damage and induce cytokine production, particularly that of interleukin-6 (IL-6). Hepcidin, which is primarily regulated by IL-6, increases after exercise. Hepcidin is a possible protective factor against the adverse effects of strenuous exercise such as oxidative stress. The aim of the study is to reveal that training increases hepcidin and attenuates increased levels of IL-6 in the hearts of exhaustively exercised rats by comparing the IL-6 and hepcidin mRNA expression levels in trained and untrained groups.Materials and methods: Thirty male Wistar albino rats were assigned to the following groups: sedentary controls (Con); untrained animals that acutely completed exhaustive exercise and were sacrificed immediately after exhaustion (UT-i) or 1 day after exhaustion (UT-1); and long-term trained animals that completed exhaustive exercise and were sacrificed immediately after exhaustion (T-i) or 1 day after exhaustion (T-1). mRNA levels were examined by reverse transcription PCR. Results: IL-6 levels significantly increased in the UT-i, T-i, and T-1 groups compared to the Con group (P = 0.000, P = 0.024, P = 0.001), with maximal IL-6 expression found in the UT-i group. Hepcidin levels significantly increased in the T-1 group (P = 0.000) compared to the control. Conclusion: Increased IL-6 levels in rats show that exhaustive exercise can cause cardiac inflammation. However, long-term training attenuated the severity of the inflammation. The possible protective effect of increased hepcidin in the trained groups can be explained by the antiinflammatory effects of IL-6 and long-term training.

Omega-3 polyunsaturated fatty acid docosahexaenoic acid and its role in exhaustive-exercise-induced changes in female rat ovulatory cycle

Exhaustive exercises can cause delayed menarche or menstrual cycle irregularities in females. Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) are incorporated into a wide range of benefits in many physiological systems. Our work aimed to assess the role of ω-3 PUFA docosahexaenoic acid (DHA) on the deleterious effects of exhaustive exercise on the female reproductive system in rats. Virgin female rats were randomly divided into 4 groups (12 rats in each): control group, omega-3 group treated with DHA, exhaustive exercise group, and exhaustive exercised rats treated with DHA. Omega-3 was given orally to the rats once daily for 4 estrous cycles. Exhaustive exercises revealed lower levels in progesterone and gonadotropins together with histopathological decrease in number of growing follicles and corpora lutea. Moreover, the exercised rats showed low levels of ovarian antioxidants with high level of caspase-3 and plasma cortisol level that lead to disruption of hypothalamic-pituitary-gonadal axis. ω-3 PUFA DHA has beneficial effects on the number of newly growing follicles in both sedentary and exercised rats with decreasing the level of caspase-3 and increasing the antioxidant activity in ovaries. Exhaustive exercises can cause ovulatory problems in female rats that can be improved by ω-3 supplementation.

Exercise-induced mitochondrial dysfunction: a myth or reality?

Beneficial effects of physical activity on mitochondrial health are well substantiated in the scientific literature, with regular exercise improving mitochondrial quality and quantity in normal healthy population, and in cardiometabolic and neurodegenerative disorders and aging. However, several recent studies questioned this paradigm, suggesting that extremely heavy or exhaustive exercise fosters mitochondrial disturbances that could permanently damage its function in health and disease. Exercise-induced mitochondrial dysfunction (EIMD) might be a key proxy for negative outcomes of exhaustive exercise, being a pathophysiological substrate of heart abnormalities, chronic fatigue syndrome (CFS) or muscle degeneration. Here, we overview possible factors that mediate negative effects of exhaustive exercise on mitochondrial function and structure, and put forward alternative solutions for the management of EIMD.

[Protective effects of short-term and long-term exercise preconditioning on myocardial injury in rats]

OBJECTIVE

To study the role and mechanism of myocardial apoptosis after short-term and long-term exercise preconditioning.

METHODS

Forty-eight male SD rats were randomly divided into control group (C), exhaust group (E), short-exercise preconditioning (S-EP) and long-term exercise preconditioning group (L-EP). Short-term and long-term exercise preconditioning were conducted for 3 days and 3 weeks of repeated intermittent swimming training program. The changes of myocardial cells were observed under light microscope. The serum levels of ischemia-modified albumin(IMA) and creatine kinase-isoenzyme(CK-MB) were detected by ELISA. Real time fluorescence quantitative PCR and Western blot were used to detect the expressions of tumor necrosis factor-α(TNF-α),Caspase-8, Caspase-3 genes and proteins in myocardial tissue. The apoptosis of cardiomyocytes was observed by TUNEL method.

RESULTS

Compared with group C, group E had serious myocardial injury. The levels of serum IMA, CK-MB and the expressions of TNF-α, Caspase-8 and Caspase-3 in myocardium were increased (P<0.05). Compared with group E, serum CK-MB and TNF-α and Caspase-8 mRNA in S-EP group were significantly lower than those in group E (P<0.05), but there was no significant difference in serum IMA and Caspase-3 mRNA and protein (P>0.05). The levels of serum IMA, CK-MB and TNF-α, Caspase-8 and Caspase-3 mRNA in L-EP group were significantly lower than those in control group (P<0.05). The apoptosis of cardiomyocytes in group E was obvious. Short-term and long-term exercise preconditioning could inhibit apoptosis. Compared with S-EP group, the apoptosis of L-EP group was significantly decreased.

CONCLUSIONS

Short-term and long-term exercise preconditioning can reduce myocardial injury after exhaustive exercise, but short-term exercise preconditioning does not alter the expression of Caspase protease. Long-term exercise preconditioning significantly inhibits Caspase-8, 3 mRNA expression and reduces protein synthesis. The inhibitive effects of long-term exercise preconditioning on myocardial cell apoptosis were stronger than those of short-term exercise preconditioning.

[Effects of preventative moxibustion on AMPK and mTOR in myocardial tissue in rats with exhaustive exercise]

OBJECTIVE

To observe the effects of preventative moxibustion on adenosine monophosphate-activated protein kinase (AMPK) and mammalian target of rapamycin (mTOR) in myocardial tissue in rats with exhaustive exercise, and to explore the action mechanism of preventative moxibustion for myocardial injury by exhaustive exercise.

METHODS

Eighteen SD male rats were randomly divided into a blank group, an exhaustive exercise group and a moxibustion group, 6 rats in each one. Rats in the blank group were treated with immobilization for 5 min per day, without any intervention. Rats in the exhaustive exercise group were treated with no intervention in the first 10 days. Rats in the moxibustion group were treated with moxibustion at "Zusanli" (ST 36) and "Guanyuan" (CV 4), 5 cones for each acupoint, for 10 days.On 11th day, rats in the exhaustive exercise group and moxibustion group were sacrificed to collect sample after exhaustive swimming, and time of exhaustive exercise was recorded. HE staining was used to observe the inflammatory changes of myocardial tissue; colorimetric method was used to measure lactic dehydrogenase (LDH), activity of superoxide dismutase (SOD) and malonaldehyde (MDA); immune suppression method was used to measure the content of creatine kinase isoenzyme (CK-MB) in serum; Elisa method was used to measure the content of troponinT (cTnT) in serum; western blot method was applied to measure the content of AMPKα2 and mTOR in myocardial tissue.

RESULTS

The time of exhaustive exercise was (4 831.17±689.88) s in the moxibustion group, which was longer than (3 509.50±1 232.49) s in the exhaustive exercise group (P<0.05); HE staining indicated structure of the myocardium was clear and inflammatory cell infiltration was reduced in the moxibustion group. Compared with the blank group, the contents of serum LDH, CK-MB, cTnT were increased in the exhaustive exercise group (all P<0.05); MDA content was increased and SOD activity was decreased (both P<0.05); the AMPK α2 content in myocardial tissue was increased and the mTOR content was decreased (both P<0.05). Compared with the exhaustive exercise group, the contents of serum LDH, CK-MB, cTnT were reduced in the moxibustion group (all P<0.05); MDA content was decreased and SOD activity was increased (both P<0.05); the AMPKα2 content in myocardial tissue was increased, and the mTOR content was decreased (both P<0.05); AMPKα2 and mTOR were negatively correlated (r=-0.764, P<0.05).

CONCLUSIONS

Preventative moxibustion is likely to regulate the expression of AMPK and mTOR to induce signaling pathway to recover myocardial injury by exhaustive exercise.

[The role of JAK2/STAT3 signaling pathway in exercise preconditioning against myocardial apoptosis]

OBJECTIVE

To study the effects of Janus kinase 2/signal transducers and activators of transcription 3 (JAK2/STAT3) in exercise preconditioning (EP) against myocardial apoptosis.

METHODS

Eighty healthy male SD rats were randomly divided into control group(C), exercise exhaust(EE) group, EP group, and EP+JAK2 inhibitor AG490(AG) group(n=20). By using 3 days intermittent treadmill exercise, the EP animal model was established, and myocardial injury was induced by exhaustive exercise on treadmill. The changes of myocardial apoptosis were evaluated by TUNEL. The expressions of Caspase-3, p-JAK2 and p-STAT3 in heart were detected by Western blot or immunohistochemistry.

RESULTS

Compared with group C, myocardial apoptosis, and the expressions of Caspase-3, p-JAK2, and p-STAT3 in heart were increased significantly in group EE. Compared with group EE, myocardial apoptosis and the expression of Caspase-3 were decreased significantly, while the expressions of p-JAK2 and p-STAT3 were increased significantly in group EP. Compared with group EP, myocardial apoptosis and the expression of Caspase-3 were increased significantly, while the expressions of p-JAK2 and p-STAT3 were decreased significantly in group EP+AG.

CONCLUSIONS

EP could increase the expressions of p-JAK2 and p-STAT3 and decrease the expression of Caspase-3 in heart, which further mitigate myocardial apoptosis. Hence, JAK2/STAT3 pathway may participate in EP against myocardial apoptosis.

Short-term effects of troxerutin (vitamin P4) on muscle fatigue and gene expression of Bcl-2 and Bax in the hepatic tissue of rats

In the current study, the effects of troxerutin (TRX) on muscle fatigue and gene expression of Bcl-2 and Bax in the hepatic tissue of rats was investigated. Forty male Wistar rats were randomly divided into 4 groups and designated as control and TRX treatment at 75 (TRX75), 150 (TRX150), and 300 mg/kg per day (TRX300). The treated groups and control group received TRX and water orally for 7 days. After an exhaustive swimming test on the 7th day, all animals were euthanized immediately and several biochemical parameters related to fatigue and gene expression of Bcl-2 and Bax in the hepatic tissue were measured. Our results showed that the exhaustion swimming time in the TRX300 groups significantly increased 1.2-fold compared with the control group (P < 0.001). TRX300 significantly reduced ALT (P < 0.05) activity and increased liver SOD activity compared with the control group (P < 0.01). Additionally, TRX significantly reduced the liver mRNA expressions of Bax (P < 0.001) and increased the Bcl-2/Bax ratio (P < 0.001) compared with the control group. Based on our data, TRX possesses anti-apoptotic and hepatoprotective action following exhaustive swimming exercise.

The influence of water temperature on sockeye salmon heart rate recovery following simulated fisheries interactions

Selective harvest policies have been implemented in North America to enhance the conservation of Pacific salmon (Oncorhynchus spp.) stocks, which has led to an increase in the capture and release of fish by all fishing sectors. Despite the immediate survival benefits, catch-and-release results in capture stress, particularly at high water temperatures, and this can result in delayed post-release mortality minutes to days later. The objective of this study was to evaluate how different water temperatures influenced heart rate disturbance and recovery of wild sockeye salmon (Oncorhynchus nerka) following fisheries interactions (i.e. exhaustive exercise). Heart rate loggers were implanted into Fraser River sockeye salmon prior to simulated catch-and-release events conducted at three water temperatures (16°C, 19°C and 21°C). The fisheries simulation involved chasing logger-implanted fish in tanks for 3 min, followed by a 1 min air exposure. Neither resting nor routine heart rate differed among temperature treatments. In response to the fisheries simulation, peak heart rate increased with temperature (16°C = 91.3 ± 1.3 beats min^-1; 19°C = 104.9 ± 2.0 beats min^-1 and 21°C = 117 ± 1.3 beats min^-1). Factorial heart rate and scope for heart rate were highest at 21°C and lowest at 16°C, but did not differ between 19°C and 21°C. Temperature affected the initial rate of cardiac recovery but not the overall duration (~10 h) such that the rate of energy expenditure during recovery increased with temperature. These findings support the notion that in the face of climate change, efforts to reduce stress at warmer temperatures will be necessary if catch-and-release practices are to be an effective conservation strategy.

Impaired Exercise Performance and Skeletal Muscle Mitochondrial Function in Rats with Secondary Carnitine Deficiency

Purpose: The effects of carnitine depletion upon exercise performance and skeletal muscle mitochondrial function remain largely unexplored. We therefore investigated the effect of N-trimethyl-hydrazine-3-propionate (THP), a carnitine analog inhibiting carnitine biosynthesis and renal carnitine reabsorption, on physical performance and skeletal muscle mitochondrial function in rats.

Methods: Male Sprague Dawley rats were treated daily with water (control rats; n = 12) or with 20 mg/100 g body weight THP (n = 12) via oral gavage for 3 weeks. Following treatment, half of the animals of each group performed an exercise test until exhaustion.

Results: Distance covered and exercise performance were lower in THP-treated compared to control rats. In the oxidative soleus muscle, carnitine depletion caused atrophy (–24%) and impaired function of complex II and IV of the mitochondrial electron transport chain. The free radical leak (ROS production relative to oxygen consumption) was increased and the cellular glutathione pool decreased. Moreover, mRNA expression of markers of mitochondrial biogenesis and mitochondrial DNA were decreased in THP-treated compared to control rats. In comparison, in the glycolytic gastrocnemius muscle, carnitine depletion was associated with impaired function of complex IV and increased free radical leak, whilst muscle weight and cellular glutathione pool were maintained. Markers of mitochondrial proliferation and mitochondrial DNA were unaffected.

Conclusions: Carnitine deficiency is associated with impaired exercise capacity in rats treated with THP. THP-induced carnitine deficiency is associated with impaired function of the electron transport chain in oxidative and glycolytic muscle as well as with atrophy and decreased mitochondrial DNA in oxidative muscle.

Athletes with higher VO2max present reduced oxLDL after a marathon race

Background

During a session of prolonged and exhaustive exercise, such as a marathon race, large quantities of free radicals are produced and can oxidise (ox) several molecules, such as low-density lipoprotein (LDL). To prevent oxidative damage, athletes present higher antioxidant levels. However, the effect of marathon running on the natural IgM or IgG anti-oxLDL autoantibodies is not understood. Thus, we investigated the effect of a marathon race on oxidative stress and the mechanisms of control of this stress.

Methods

Blood samples of 20 marathon runners were collected 24 hours before, immediately and 72 hours after a marathon race to evaluate: plasma lipid profile; serum levels of oxLDL and anti-oxLDL autoantibodies (IgM and IgG isotype) and total antioxidant capacity (TAC). Maximum oxygen uptake (VO2max) was also determined.

Results

Immediately after the race, oxLDL and TAC levels decreased in comparison to the basal levels; however, the IgM or IgG anti-oxLDL levels remain unchanged. Whereas no differences were observed in the IgM or IgG anti-oxLDL levels 72h after the marathon, the oxLDL and TAC levels returned to the basal values. Significant positive correlations were observed between oxLDL and LDL-cholesterol before, and 72h after the marathon. Significant negative correlations were observed between oxLDL and VO2max immediately after the marathon and 72 h later, as well as between oxLDL and TAC 72 h after the race.

Conclusions

Athletes with a higher VO2max and total antioxidant activity presented reduced LDL oxidation. The levels of IgM or IgG anti-oxLDL autoantibodies were not affected by running the marathon.

Drag-reducing polymers increase exercise tolerance in an ischemic hind-limb rat model

OBJECTIVE

Drag-reducing polymers are long-chain, blood soluble macromolecules that can improve microcirculation in vivo. This study aimed to examine the effects of drag-reducing polymers on exercise tolerance in a rat model of hind-limb ischemia.

METHODS

After adaptive running training, bilateral femoral artery ligation models were established in 64 Wistar rats. During an exhaustive exercise, polyethylene oxide or normal saline was intravenously injected to each group (n = 32) at 4 mL/h for 10 min. The exhaustive exercise time was recorded, and lactic acid levels in gastrocnemius muscle and serum were measured. Serum levels of nitric oxide, creatine kinase and lactate dehydrogenase were measured as biomarkers of physical fatigue.

RESULTS

Compared with saline-treated control group, rats in polyethylene oxide-treated group had longer exhaustive exercise time (774.7 ± 171.5 s vs. 687.6 ± 166.1 s, p = 0.043), and lower lactic acid level in gastrocnemius muscle (p < 0.01) but no significant difference in serum lactic acid level between two groups was observed (p > 0.05). Nitric oxide level was higher in polyethylene oxide group than in controls (p < 0.05), but no significant differences in serum creatine kinase and lactate dehydrogenase levels between two groups were observed (p > 0.05).

CONCLUSION

Drag-reducing polymers contribute to the enhancement of exercise endurance and exert anti-fatigue effect.

A physiological comparison of three techniques for reviving sockeye salmon exposed to a severe capture stressor during upriver migration

Capture of fish in commercial and recreational fisheries causes disruption to their physiological homeostasis and can result in delayed mortality for fish that are released. For fish that are severely impaired, it may be desirable to attempt revival prior to release to reduce the likelihood of post-release mortality. In this study, male sockeye salmon (Oncorhynchus nerka) undergoing their upriver migration were used to examine short-term physiological changes during the following three revival treatments after beach seine capture and air exposure: a pump-powered recovery box that provided ram ventilation at one of two water flow rates; and a cylindrical, in-river recovery bag, which ensured that fish were oriented into the river flow. Beach seine capture followed by a 3 min air exposure resulted in severe impairment of reflexes such that fish could not maintain positive orientation or properly ventilate. All three revival treatments resulted in significant reductions in reflex impairment within 15 min, with full recovery of reflex responses observed within 60-120 min. For most variables measured, including plasma lactate, cortisol and osmolality, there were no significant differences among revival treatments. There was some evidence for impaired recovery in the low-flow recovery box, in the form of higher haematocrit and plasma sodium. These data mirror published recovery profiles for a recovery box study in the marine environment where a survival benefit occurred, suggesting that the methods tested here are viable options for reviving salmon caught in freshwater. Importantly, with most of the benefit to animal vitality accrued in the first 15 min, prolonging recovery when fish become vigorous may not provide added benefit because the confinement itself is likely to serve as a stressor.

Effect of endurance training and cinnamon supplementation on post-exercise oxidative responses in rats

Despite the preventative and therapeutic effects of regular exercise, exhaustive exercise may be harmful to health. The present study aimed to determine the protective effect of endurance training and cinnamon bark extract (CBE) supplementation on oxidative responses induced by an exhaustive exercise schedule in rats. The rats were randomly divided into the following five groups of 6; control sedentary (Con/Sed), control exercised (Con/Ex), trained exercised (Tr/Ex), supplemented exercised (Sup/Ex), and trained, supplemented and exercised (Tr/Sup/Ex). Animals in exercise groups ran on a rodent treadmill for an 8-week endurance training program. At the end of the experiment, blood samples were collected and (MDA) and total thiol (TT) levels were measured in plasma. Glutathione peroxidase (GPX), superoxide dismutase (SOD), and catalase (CAT) activities were determined in soleus muscles. Results showed significant increases in SOD activity and malondealdehyde (MDA) levels in the soleus muscles and serum of exercised rats fed with the normal diet. The exhaustive exercise also induced a decrease in serum total thiol level and GPX activity. Elevated levels of total thiol and total antioxidant capacity (TAC) and reduced serum MDA levels were found in the Sup/Ex and Tr/Sup/Ex groups. CAT and GPX activities increased by CBE treatment in trained rats. Regular training increased CAT and GPX activities in the Tr/Sup/Ex group. CAT, GPX and SOD activities were not affected by the CBE treatment in untrained rats. Results suggest that additional use of regular training and CBE supplementation increase TAC and protect healthy male rats against oxidative damage induced by exhaustive exercise.

Exercise myopathy: changes in myofibrils of fast-twitch muscle fibres

The purpose of the present study was to determine the relationships between the changes of myofibrils in fast-twitch oxidative-glycolytic (type IIA) fibres and fast-twitch glycolytic (type IIB) muscle fibres, protein synthesis and degradation rate in exercise-induced myopathic skeletal muscle. Exhaustive exercise was used to induce myopathy in Wistar rats. Intensity of glycogenolysis in muscle fibres during exercise, protein synthesis rate, degradation rate and structural changes of myofibrils were measured using morphological and biochemical methods. Myofibril cross sectional area (CSA) in type IIA fibres decreased 33% and type IIB fibres 44%. Protein degradation rate increased in both type IIA and IIB fibres, 63% and 69% respectively in comparison with the control group. According to the intensity of glycogenolysis, fast oxidative-glycolytic fibres are recruited more frequently during overtraining. Myofibrils in both types of fast-twitch myopathic muscle fibres are significantly thinner as the result of more intensive protein degradation. Regeneration capacity according to the presence of satellite cells is higher in type IIA fibres than in type IIB fibres in myopathic muscle.

Exercise preconditioning-induced late phase of cardioprotection against exhaustive exercise: possible role of protein kinase C delta

The objective of this study was to investigate the late cardiac effect of exercise preconditioning (EP) on the exhaustive exercise-induced myocardial injury in rats and the role of protein kinase C (PKC) in EP. Rats were subjected to a run on the treadmill for four periods of 10 min each at 30 m/min with intervening periods of rest of 10 min as an EP protocol. The exhaustive exercise was performed 24 h after EP. PKC inhibitor chelerythrine (CHE) was injected before EP. The results showed that EP increased the running ability of rats, and alleviated the exhaustive exercise-induced injury in cardiomyocytes, but pretreatment with PKC inhibitor CHE did not abolish the late phase cardioprotection of EP. A significant increase of PKCδ, both at the protein level and the mRNA level in the left ventricular myocardium of rats, accompanied by its activated form (phosphorylated on Thr507, p-PKCδThr507) translocated to intercalated disks and was found in the late phase of EP. This circumstance was not attenuated by CHE. These results suggested that a high level of PKCδ might be involved in cardioprotection against myocardial damage, but if activated PKCδ at reperfusion took on a key role in cardioprotection was still an outstanding question.

Exhaustive exercise and vitamins C and E modulate thyroid hormone levels at low and high altitudes

Thyroid hormones play an important role in cell growth and differentiation and regulation of oxygen consumption and thermogenesis. The effect of altitude and vitamin supplementation on thyroid hormone levels in animals or humans performing acute exhaustive exercise have not been investigated before. Therefore, we thought to test whether exhaustive exercise-induced stress with antioxidant supplementation was capable of modulating the level of thyroid hormones at different altitudes. Serum levels of T4 (Thyroxin), T3 (Triiodothyronine), and TSH (Thyroid Stimulating Hormone) were measured in rats (N=36) born and bred in low altitude (600 m above sea level) and high altitude (2200 m above sea level) following forced swimming with or without vitamins C and E (25 mg/kg) pre-treatments. Thyroid levels were significantly decreased in resting rats at high altitude compared to low altitude, and swimming exercise moderately increased T3 and TSH at both high and low altitudes, whereas T4 was markedly increased (62 %) at low altitude compared to a moderate high altitude increase (28 %). Co-administration of vitamins C and E augmented the observed forced swimming-induced thyroid release. However, the conversion of T4 to T3 was reduced in both altitude areas following swimming exercise and vitamin pre-treatment had no effect. We conclude that acute stress induced thyroidal hormones in rats, which was augmented by antioxidant drugs in both high and low altitude areas. These findings may play an important role in the human pathophysiology of thyroid gland at different altitudes.

Effect of Achyranthes bidentata polysaccharides on the expression of BCL-2 and bax in hepatic tissues after exhaustive exercise in rats

This study aims to assess the effects of Achyranthes bidentata polysaccharides (ABPS) on the expression of bcl-2 and bax in hepatic tissues after exhaustive exercise in order to provide theoretical support for the application of ABPS in the field of sports nutrition. Thirty male Sprague-Dawley rats were randomized into three groups, each consisting of 10 rats: Normal control group (NCG), Exhausting exercises control group (EECG), ABPS treated group (ATG). ABPS were fed orally by gastric intubation to rats of ABPS treated group (ATG) once daily for 7 days. Control animals (EECG and NCG) received the same amount of isotonic sodium chloride solution. Exhaustive exercise was performed on a rodent treadmill. The SP (streptavidin peroxidase) method for immunohistochemical staining was adopted to test the protein expression of bax and bcl-2 in the hepatic tissues of the rats. Exhausting exercises increased bax protein expression of hepatic tissues of rats and bax/bcl-2 ratio dramatically, but a decreased bcl-2 protein expression. In the rats fed ABPS orally by gastric intubation, the bax protein expression and bax/bcl-2 ratio obviously decreased, while bcl-2 protein expression increased. The result indicated that bax and bcl-2 co-regulated the exercise-induced hepatocyte apoptosis. Feeding ABPS orally by gastric intubation to rats can inhibit the hepatocyte apoptosis in exhaustive exercise.

A comparison of the effects of fatigue on subjective and objective assessment of situation awareness in cycling

Maximal effort on a 30 km Time Trial (TT30) was examined to assess whether it would elicit changes in objective and subjective tests of the participants' perception of the environment and their ability to anticipate future occurrences (situation awareness; SA) and to determine the effect of post-exercise recovery on SA. Nine experienced (5.22 ± 2.77 years) road cyclists had their objective and subjective levels of SA assessed prior to and at the completion of two TT30. The participants' results were compared to measurements of maximal oxygen uptake (VO2max), peak power output (PPO), age and years of competitive cycle racing experience. Fatigue resulting from maximal effort on a TT30 produced significant changes in both the objective and subjective test of SA. Effect sizes of 0.93 and 0.99 indicated that the first and second TT30 were likely or almost certain to have a beneficial effect on the objective assessment of SA. However, the effect sizes of 0.97 and 0.95 relating to the subjective assessment of cognitive performance on the first and second TT30 showed that it was very likely the participants' had an increased difficulty in maintaining SA. A recovery period of up to three minutes post TT30 had no effect on SA. Changes in SA had no relationship with measurements of VO2max, peak power output (PPO), age and years of competitive cycle racing experience. The findings suggest that within a laboratory environment, participants consistently underestimate their ability to make accurate assessments of their cycling environment compared to objective measures of their SA. Key PointsExhaustive exercise from a TT30 produces significant changes in both subjective and objective SA.This study indicates that fatigued participants underestimate their ability to maintain SA.A time period of three minutes is not enough to observe a recovery effect on subjective or objective SA.Both the objective and subjective tests proved to be reliable assessments of SA.