Short duration exhaustive aerobic exercise induces oxidative stress: a novel play-oriented volitional fatigue test

AIM: Exercise is associated with the generation of reactive oxygen and nitrogen species. This study examined the oxidative stress in response to a novel volitional fatigue test. METHODS: Eleven male college students performed a volitional fatigue test consisting of shuttle runs with a tennis racquet in the hand towards the left and right sidelines within the tennis singles court in an attempt to hit tennis balls until exhaustion. A tennis ball serving machine was adjusted to alternate feeds to the forehand and backhand sides of the subjects, standing at the baseline, at a frequency of 20 balls per minute. RESULTS: Mean time to volitional fatigue was 5.9+/-1.3 min and mean heart rate at volitional fatigue was 189+/-8.1 beats x min(-1). The volitional fatigue test resulted in significant increases in blood thiobarbituric acid-reactive substances (22%), protein carbonyls (58%), catalase activity (143%), total antioxidant capacity (34%) and oxidized glutathione (GSSG, 81%) concentration, as well as significant decreases in reduced glutathione (GSH, 15%) concentration and GSH/GSSG ratio (56%) immediately postexercise, as compared to the pre-exercise concentration. CONCLUSION: The data provide evidence that acute short duration exhaustive aerobic exercise in the form of a novel volitional fatigue test is capable of inducing oxidative stress. This novel test could serve as an alternative exercise modality to study oxidative stress.     

Competition and food restriction effects on oxidative stress in judo

We examined the effects of weight loss induced by restricting energy and fluid intake on antioxidant status and oxidative stress of judo athletes. Twenty male judoka were randomly assigned to one of two groups (Group A: called diet, n = 10; height 174.8 +/- 1.9 cm, body weight 75.9 +/- 3.1 kg; they were asked to lose approximately 5 % of their body weight through self-determined means during the week before the competition; Group B: called control, n = 10; height 176.4 +/- 1.1 cm, body weight 73.3 +/- 6.3 kg maintained their body weight during the week before the competition). A battery of tests was performed during a baseline period (T1) on the morning of a simulated competition (T2) and 10 minutes after the end of the competition (T3). These tests included assessment for body composition, determination of lag phase (Lp) before free radical induced oxidation, maximum rate of oxidation (Rmax) during the propagating chain reaction and maximum amount of conjugated dienes (CDmax) accumulated after the propagation phase, and lipidic profile. Uric acid concentrations were also evaluated in plasma. Dietary data were collected using a 7-day diet record. We noted that the athletes followed a low carbohydrate diet whatever the period of the investigation. Concerning antioxidant nutrients, we can notice that mean nutritional intakes are in the normal range values for vitamin A, C and E at T1 and T2. Rapid weight loss induced a significant increase in Lp values (p < 0.05) and uric acid concentrations without alterations in oxidative stress. Our data also showed that the competition induced the same changes of oxidative-antioxidant status whatever the dietary intake during the seven days before the competition. Moreover, the effect of the competition on the antioxidant and oxidant parameters was more pronounced than the diet. Theses results could be linked to the food containing a large proportion of PUFA and a relative low proportion of carbohydrates.     

Regulation of myocardial contractility in exhaustive exercise

The impact of exhaustive exercise on myocardial function is poorly understood. Experimental parameters of contractility that are completely devoid of other influences do not exist. Furthermore, the problem is compounded by the fact that exhaustive work comprises myriad exercise paradigms and fatigue may be the result of numerous possible mechanisms. Despite these confounding variables, there is evidence that stroke volume may be impaired by prolonged work in humans. These studies implicated reduced venous return and not contractility as the reason. Experiments with the rat model have indicated that treadmill running at about 60% of VO2max results in reduced isometric twitch tension in isolated trabecular tissue. The data are consistent with the notion that contractility is substantially reduced. The mechanism for this inhibition is unknown. In separate studies using a similar model, it has been shown that Ca2+ uptake by the sarcoplasm reticulum of the myocardium in vitro is reduced by fatigue. It is conceivable that in exhaustive exercise, there may be only a slight effect on contractility in vivo but that substantial adjustments in intracellular homeostasis are required in order to achieve this. Future considerations should include a rigorous analysis of contractility and the factors that regulate it, as well as the choice of animal and exhaustion models.     

Obesity exacerbates oxidative stress levels after acute exercise

INTRODUCTION/PURPOSE: This study compared oxidative stress levels and antioxidant capacity in nonobese and obese participants after acute resistance (RX) and aerobic exercise (AX). METHODS: Blood samples were collected from 28 nonobese (mean = 20.8% body fat) and obese (mean = 35.0% body fat) participants pre- and immediately post-RX and AX. Lipid hydroperoxides (PEROX), malondialdehyde (TBARS) and total antioxidant status (TAS) were measured. Oxygen consumption (VO2) and minute ventilation (VE) values were determined during each exercise session. RESULTS: In both groups, PEROX and TBARS were elevated post-RX and AX, with the greater elevations occurring in the obese group in each case (P < 0.05). In the obese, TBARS increased by 42% and 41% post-RX and AX, respectively, compared with 7.1% and 26.9% in the nonobese group. PEROX increased by 100% and 70% post-RX and AX, respectively, in the obese, and by 85% and 62% in the nonobese. TAS was 17% higher (P < 0.05) post-RX in the nonobese compared with the obese, whereas TAS values were not different post-AX. Peak and average VE, and relative VO2). rates were higher in the obese post-AX compared with the nonobese (P < 0.05) Correlations existed between the exercise-induced change in PEROX and body fat, vitamin C and A intake, peak oxygen consumption, and exercise ventilation rates in the obese group (r = 0.784-0.776, P < 0.05). In both groups, the exercise-induced changes in PEROX were associated with vitamin C intake, exercise ventilation rates, VO2peak, and plasma triglycerides (r = 0.669-0.558, P < 0.05). CONCLUSION: Lipid peroxidation is elevated in both RX and AX, and it is exacerbated in the obese. The mechanisms underlying this response in each exercise may be different but could involve plasma triglycerides, oxygen consumption, and antioxidant intake.     

Decreased blood oxidative stress after repeated muscle-damaging exercise

PURPOSE: To examine the effect of repeated muscle-damaging exercise on the time-course changes in several indices of muscle damage, and to compare them with changes in blood oxidative stress indices. METHODS: Twelve females underwent an isokinetic exercise session consisting of 75 lengthening knee flexions, which was repeated after 3 wk. Isometric torque, range of movement (ROM), delayed-onset muscle soreness (DOMS), creatine kinase (CK), reduced glutathione (GSH), oxidized glutathione (GSSG), thiobarbituric acid-reactive substances (TBARS), protein carbonyls, catalase, uric acid, bilirubin, and total antioxidant capacity (TAC) in blood were measured before, immediately after, and 1, 2, 3, 4, and 7 d after lengthening contractions. RESULTS: All muscle damage indices (torque, ROM, DOMS, and CK) changed significantly after exercise. The concentration of all oxidative stress indices changed significantly in a way indicating increased oxidative stress in the blood (GSH and GSH/GSSG decreased, whereas GSSG, TBARS, protein carbonyls, catalase, uric acid, bilirubin, and TAC increased), peaking in all but bilirubin at 3 d and returning to baseline values by 7 d after exercise. The repeated bout of lengthening contractions induced significantly less changes in indices of muscle damage and blood oxidative stress than the first bout. In general, from the increasing or decreasing area under the curve calculated for each oxidative stress index, the second bout produced 1.8- to 6.1-fold less changes in oxidative stress than after the first bout. CONCLUSION: A repeated bout of lengthening contractions attenuated muscle damage and blood oxidative stress compared with the first bout.     

The paradox of oxidative stress and exercise with advancing age

Aging, vascular function, and exercise are thought to have a common link in oxidative stress. Both antioxidant supplementation and exercise training have been identified as interventions that may reduce oxidative stress, but their interaction in older humans is not well understood.     

Thrombin potential and thrombin generation after exhaustive exercise

Exhaustive exercise leads to an activation of blood coagulation, but the implications of this activation are still unclear. The aim of this study was to investigate if a hypercoagulant stage exists after exhaustive treadmill- or cycle exercise; intrinsic and extrinsic endogenous thrombin potential (ETP) were measured by using the method of Hemker et al. Thirteen healthy male subjects underwent an exhaustive treadmill (TR) or cycle (CY) ergometer test and a control-day in random order. Blood samples were taken, repeatedly, after a 30 min rest, immediately before and after, and 1 h after exercise for measuring intrinsic and extrinsic total thrombin potential (TTPin, TTPex) (including free and alpha 2 -macroglobulin-bound thrombin) and endogenous thrombin potential (ETPin, ETPex), aPTT, PT, F1 + 2 and TAT. In comparison to the pre-value taken immediately before the exercise, the intrinsic TTP was significantly (p < 0.05) increased directly after exercise (TR-TTPin, + 11.6 %; CY-TTPin, + 11.5 %). In contrast, ETPin remained unchanged after both exercises. Additionally for TTPex and ETPex, no changes after exercise were detectable. aPTT was significantly (p < 0.05) shorter after exercise (TR-aPTT, - 16.2 %; CY-aPTT - 17.5 %), F1 + 2-concentrations were higher (p < 0.05) (TR-F1 + 2, + 21.2 %; CY-F1 + 2, + 9.8 %), but TAT remained unchanged. Differences between TR or CY could not be determined. These results show the expected shortening of aPTT and the increase of F1 + 2 indicating an activation of the coagulation system during exercise. However, the unchanged intrinsic and extrinsic ETP lead to the conclusion that in healthy young male subjects the potential for thrombin generation is insignificant, is directly counterbalanced by alpha 2-macroglobulin and is independent of the type of exhaustive exercise done.     

Antioxidant supplementation does not attenuate oxidative stress at high altitude

INTRODUCTION: Hypobaric hypoxia and heightened metabolic rate increase free radical production. PURPOSE: We tested the hypothesis that antioxidant supplementation would reduce oxidative stress associated with increased energy expenditure (negative energy balance) at high altitude (HA 4300 m). METHODS: For 12 d at sea level (SL), 18 active men were fed a weight-stabilizing diet. Testing included fasting blood and 24-h urine samples to assess antioxidant status [plasma alpha-tocopherol, beta-carotene, lipid hydroperoxides (LPO), and urinary 8-hydroxydeoxyguanosine (8-OHdG)] and a prolonged submaximal (55% Vo2peak) oxidative stress index test (OSI) to evaluate exercise-induced oxidative stress (plasma LPO, whole blood reduced and oxidized glutathione, glutathione peroxidase, and urinary 8-OHdG). Subjects were then matched and randomly assigned to either a placebo or antioxidant supplement group for a double-blinded trial. Supplementation (20,000 IU of beta-carotene, 400 IU alpha-tocopherol acetate, 500 mg ascorbic acid, 100 microg selenium, and 30 mg zinc, or placebo) was begun 3 wk prior to and throughout a 14-d HA intervention. At HA, subjects' daily energy intake and expenditure were adjusted to achieve a caloric deficit of approximately 1400 kcal. Fasting blood and 24-h urine samples were collected throughout HA and the OSI test was repeated on HA day 1 and day 13. RESULTS: Resting LPO concentrations increased and urinary 8-OHdG concentrations decreased over HA with no effect of supplementation. Prolonged submaximal exercise was not associated with increased concentrations of oxidative stress markers at SL or HA. CONCLUSIONS: Antioxidant supplementation did not significantly affect markers of oxidative stress associated with increased energy expenditure at HA.     

Cerebral cortex activity during supramaximal exhaustive exercise

AIM: The purpose of this study was to examine the effect of fatigue resulting from supramaximal dynamic exercise on cerebral cortex activity. METHODS: Five healthy male subjects (age 24.6+/-0.4 years, body weight 62.9+/-1.1 kg, height 175.3+/-1.2 cm, and maximal O2 uptake per body mass 48.4+/-1.3 ml/kg/min) participated in this study. All subjects performed at 120% of maximal oxygen uptake (VO2peak) on a cycle ergometer until reaching a state of volitional fatigue. Cerebral oxygenation was measured by near-infrared spectroscopy (NIRS) throughout the supramaximal constant exhaustive exercise. RESULTS: The mean exercise duration of the subjects was 147.2+/-3.4 s. The peak value of blood lactate concentration within 3-10 min after the exercise test was 14.4+/-0.1 mmol/l. Cerebral oxygenation (8.8+/-1.8 micromol/l) was increased significantly during the first minutes of exercise compared with the pre-exercise value (p<0.05) and cerebral oxygenation decreased with the passage of time during exercise. Cerebral oxygenation at the end of exercise decreased significantly compared with the resting value (-29.9+/-3.4 micromol/l, p<0.05). CONCLUSION: These findings suggest that the exhaustive exercise induces the decrease of cerebral function and that the fatigue resulting from dynamic exercise decreases the cerebral cortex activity.     

The effects of acute exercise on neutrophils and plasma oxidative stress

PURPOSE: To investigate the influence of intensity versus total energy expenditure on neutrophilia and blood oxidative stress to acute exercise. METHODS: Nine males (18-30 yr) completed one maximal (Max) and three submaximal exercise sessions: 1) 45 min at 10% above (LT+) lactate threshold (LT), 2) 45 min at 10% below (LT-) LT, and 3) 10% below LT until caloric expenditure equaled the 10%+ trial (LT-kcal). Blood was sampled before (PRE), immediately (POST), 1 h, and 2 h after exercise to measure neutrophils, myeloperoxidase, superoxide (O(2)-), neutrophil activation (O(2)-/neutrophils), ascorbic acid, uric acid, malondialdehyde, and lipid hydroperoxides. RESULTS: Intensity-dependent neutrophilia occurred POST exercise with significant increases (P 相似文献   

Central and peripheral fatigue following non‐exhaustive and exhaustive exercise of disparate metabolic demands

The development of fatigue after non‐exhaustive and exhaustive exercise eliciting differing metabolic demands is poorly understood. Sixteen active males completed five cycling trials. The first trial established the lactate threshold (LT) and maximal oxygen uptake (VO_2max). Two of the remaining trials were completed at a severe intensity (halfway between LT and VO_2max, SI) and two at a moderate intensity (90% LT, MI). Each trial involved two non‐exhaustive bouts matched for work between intensities before cycling to exhaustion. Responses to stimulation of the femoral nerve and motor cortex were determined after each bout to determine peripheral and central fatigue. Corticospinal excitability, cortical silent period (cSP), short‐interval intracortical inhibition (SICI), and intracortical facilitation (ICF) were also assessed. Non‐exhaustive cycling induced greater peripheral and central fatigue in the SI compared with the MI (P < 0.05). At exhaustion, there was no difference between intensities; however, peripheral fatigue tended to be greater in the SI vs MI (?31% vs ?17%, respectively, P = 0.051). Exhaustive cycling increased SICI (24%, P < 0.001) and reduced the cSP (?14%, P < 0.001) in the SI, whereas ICF was reduced in the MI (?16%, P < 0.001). These findings demonstrate exercise‐induced metabolic stress accelerates the development of peripheral and central fatigue, and differentially influences intracortical excitability.     

Diurnal variation in long- and short-duration exercise performance and mood states in boys

The aim of the present study was to investigate the effect of time-of-day on long- and short-duration exercise performance and mood states. Twelve prepubertal boys (age 10.7 ± 0.4 years; height 1.47 ± 0.6 m; body-mass 44.8 ± 3.1 kg) performed three test sessions at 08:00, 14:00 and 18:00 h. During each session, they performed the squat jump (SJ), the countermovement jump (CMJ) and the Yo–Yo test. Oral temperature was recorded at the beginning of each test session. Moreover, boys completed the profile of mood states questionnaire before performing the physical tests. The results showed that SJ (p < 0.05), CMJ (p < 0.01) and oral temperature (p < 0.001) were higher at 14:00 and 18:00 h compared to 08:00 h. Maximal aerobic velocity during the Yo–Yo test was higher only at 18:00 h than 08:00 h (p < 0.05). However, mood states were not significantly different between 08:00, 14:00 and 18:00 h. Likewise, we did not observe significant correlations between mood states and physical performances. In conclusion, in boys, both long- and short-duration exercises, performances were better in the afternoon than the morning.     

Antioxidant status and oxidative stress in professional rugby players: evolution throughout a season

Physical training is known to increase the antioxidant defence system and reduce exercise-induced oxidative stress. However, intense physical aerobic and anaerobic training and competition such as those imposed on professional rugby players, can induce an increase of oxidative stress which can be implicated with the arrival of overtraining. The aim of this study was to test the effect of training and competition load on oxidative stress, antioxidant status, haematological, and cell damage markers in high-level rugby players during a competitive season. Blood samples were collected four times in one year. Oxidative stress (Rmax), antioxidant (vitamin E, uric acid, TAC, and lag phase), haematological (neutrophils and monocytes) and biochemical (CK and myoglobin) parameters, as well as training and competition load, and competition results were measured. Intense periods of training and competition (T1 and T4) induced a significant higher maximum rate of conjugated dienes oxidation (+67.2% in T1 and +40.6% in T4) compared to those observed at the reference time (T3). Those periods also induced an increase in uric acid (+6.9% and 3.2%), and inflammatory markers such as monocytes (+13.3% and 10.7%). On the other hand, vitamin E (-8.7% in T1) and lag phase (-23.0% and -14.7%) were lower during these periods showing a possible training-induced antioxidant down-regulation. The less intense period of training (T2) was accompanied by lower neutrophils (-8.5%), CK (-53.7%), and myoglobin (-16.2%) values. The results suggest that oxidative stress and antioxidant measurement are significant in the biological follow-up of athletes.     

Effect of previous exhaustive exercise on metabolism and fatigue development during intense exercise in humans

The present study examined how metabolic response and work capacity are affected by previous exhaustive exercise. Seven subjects performed an exhaustive cycle exercise (～130%‐max; EX2) after warm‐up (CON) and 2 min after an exhaustive bout at a very high (VH; ～30 s), high (HI; ～3 min) or low (LO; ～2 h) intensity. Compared with CON, performance during EX2 was reduced (P<0.05) more in HI and LO than in VH (61±4% and 68±3% vs 35±4%). The muscle glycogen before EX2 was lower (P<0.05) in LO than in HI and VH, but the muscle glycogen utilization rates during EX2 were not different. Muscle glycogen concentration before EX2 was related (P<0.05) to the mean rate of muscle glycogen utilization during EX2 in HI and VH, and the mean rate of muscle lactate accumulation in LO. In HI, muscle pH before EX2 was lower (P<0.05) compared with VH and LO, but the same in HI and VH at the end of EX2. In HI, muscle pH before and after EX2 was inversely related (P<0.05) to the decrease in EX2 performance. Thus, muscle glycogen availability and low muscle pH do not per se control but appear to affect the rate of glycogenolysis/glycolysis and fatigue development during a repeated high‐intensity exercise lasting 1/2–2 min.     

Leg stiffness modulation during exhaustive stretch-shortening cycle exercise

The present study examined the effects of muscle activity modulation on leg stiffness during an exhaustive stretch-shortening cycle (SSC) exercise in eight male subjects. Reaction force, electromyography (EMG) of the soleus (Sol), gastrocnemius (Ga) and vastus lateralis (VL) muscles and sledge seat position were recorded during the SSC exercise, consisting of 100 maximal intermittent drop jumps followed by a continuous submaximal jumping until exhaustion, on a sledge apparatus. Metabolic loading was determined by measuring blood lactate (La). No change was found in leg stiffness during the maximal jumps, whereas the subsequent submaximal jumping induced a significant reduction by 27+/-12% (P<0.05). Leg stiffness was closely related to the EMG ratio between the braking and push-off phases in Sol (r=0.81, P<0.05) and particularly in Ga (r=0.98, P<0.001) (but not in VL, r=0.64, NS) at the end of the submaximal jumping. Furthermore, the post-exercise La was significantly associated with the EMG ratio at the end of the submaximal jumping in Sol (r=-0.88, P<0.01) and Ga (r=-0.98, P<0.001). These results indicate that activity modulation between the braking and push-off phases in the triceps surae muscle, particularly in Ga, plays an important role in leg stiffness adjustments during fatiguing SSC exercise. It is suggested that efficient activity modulation (i.e. high EMG ratio) of the triceps surae muscle during an intensive fatiguing SSC exercise may postpone the exhaustion and development of metabolic fatigue.