The effects of beta alanine plus creatine administration on performance during repeated bouts of supramaximal exercise in sedentary men.

AIM: The aim of this study was to investigate the effects of beta alanine and/or creatine supplementation on performance during repeated bouts of supramaximal exercise in sedentary men. METHODS: Forty-four untrained healthy men (aged 20-22 years, weight: 68-72 kg, height: 174-178 cm) participated in the present study. After performing the Wingate Test (WAnT) for three times in the baseline exercise session, the subjects were assigned to one of four treatment groups randomly: 1) placebo (P; 10 g maltodextrose); 2) creatine (Cr; 5 g creatine plus 5 g maltodextrose); 3) beta-alanine (ß-ALA; 1,6 g beta alanine plus 8,4 g maltodextrose); and 4) beta-alanine plus creatine (ß-ALA+Cr; 1,6 g beta alanine plus 5 g creatine plus 3,4 g maltodextrose). Participants were given the supplements orally twice a day for 22 consecutive days, then four times a day for the following 6 days. After 28 days, the second exercise session was applied during which peak power (PP) and mean power (MP) were measured and fatigue index (FI) was calculated. RESULTS: PP and MP decreased and FI increased in all groups during exercise before and after the treatment. During the postsupplementation session PP2 and PP3 increased in creatine supplemented group (from 642.7±148.6 to 825.1±205.2 in PP2 and from 522.9±117.5 to 683.0±148.0 in PP3, respectively). However, MP increased in ß-ALA+Cr during the postsupplementation compared to presupplementation in all exercise sessions (from 586.2±55.4 to 620.6±49.6 in MP1, from 418.1±37.2 to 478.3±30.3 in MP2 and from 362.0±41.3 to 399.1±3 in MP3, respectively). FI did not change with beta alanine and beta alanine plus creatine supplementation during the postsupplementation exercise session. CONCLUSION: Beta-alanine and beta alanine plus creatine supplementations have strong performance enhancing effect by increasing mean power and delaying fatigue Index during the repeated WAnT.

Effects of exercise preconditioning on intestinal ischemia-reperfusion injury.

BACKGROUND: To investigate the effects of exercise preconditioning on oxidative injury in the intestinal tissue of rats. METHODS: Sixty male Wistar rats were randomly divided into six groups as sham (n = 10), ischemia-reperfusion (n = 10), exercise (n = 10), exercise plus ischemia-reperfusion (n = 10), ischemic preconditioning (n = 10), and ischemic preconditioning plus ischemia-reperfusion groups (n = 10). Tissue levels of malondialdehyde and activities of myeloperoxidase and superoxide dismutase, and serum levels of tumor necrosis factor-alpha and interleukin-6 were measured. Intestinal tissue histopathology was also evaluated by light microscopy. RESULTS: Tumor necrosis factor-alpha concentrations significantly decreased in the exercise group compared to the sham group (p < 0.05). Myeloperoxidase activity significantly increased and superoxide dismutase activity significantly decreased in ischemia-reperfusion group compared to the sham group (p < 0.05). Superoxide dismutase activity in the ischemic preconditioning and ischemic preconditioning plus ischemia-reperfusion groups were significantly higher compared to the ischemia-reperfusion and exercise groups (p < 0.05). Histopathologically, intestinal injury significantly attenuated in the exercise plus ischemia-reperfusion group compared to the ischemia-reperfusion group. CONCLUSIONS: The results of the present study indicate that exercise training seems to have a protective role against intestinal ischemia-reperfusion injury (Tab. 3, Fig. 1, Ref. 35).

Donepezil-induced response of Spirulina supplemented rat urinary bladder.

OBJECTIVE: At present, very little is known about the effects of donepezil on vascular reactivity. The aim of the present study was to evaluate the responses of rat urinary bladder to donepezil (10-10-3x10-4 M) and the role of Spirulina supplementation in these effects. MATERIAL AND METHODS: Animals were divided into the two groups of six animals in each group. The first group received only distilled water daily as vehicle for six weeks and served as the control. The second group received Spirulina 750 mg kg -1 orally, daily for six weeks and served as the spirulina group. Preparations of rat urinary bladder were used from both groups. RESULTS: Donepezil produced concentration dependent relaxation of rat urinary bladder preparations pre-contracted with KCl.The pIC50 value, but not the maximal response of donepezil, was significantly lower (p<0.05) in the Spirulina supplemented group. CONCLUSIONS: These results demonstrated for the first time that spirulina treatment can affect urinary bladder activity (Fig. 1, Ref. 20).

Protective effects of curcumin supplementation on intestinal ischemia reperfusion injury.

The aim of this study was to investigate the effects curcumin on inflammation and oxidative stress markers in the intestinal ischemia reperfusion (IIR) injury induced rats. Rats were divided into four groups: sham (S), intestinal IR (IIR), curcumin plus sham (CS), and curcumin plus intestinal IR (CIIR). Curcumin was given 200 mg kg⁻¹ for 20 days. IIR was produced by 45 min of intestinal ischemia followed by a 120 min of reperfusion. Although interleukin-6 levels tended to increase in IIR group tumor necrosis factor-α levels were not different. Intestinal myeloperoxidase activity in CS group was lower than IIR group. In intestine and heart tissues, malondialdehyde levels in CS and CIIR groups were lower than S and IIR groups. Superoxide dismutase activity in CIIR group was higher than IIR group in intestine and lung tissues. Curcumin has a protective role against ischemia reperfusion injury.

Age and sex affect spatial and emotional behaviors in rats: the role of repeated elevated plus maze test.

The main objective of the study was to investigate the effects of age and sex differences on locomotor activity, learning and memory in rats. Another objective was to investigate whether repeated elevated plus maze tests induce anxiety in rats. Eighty Wistar rats were divided into eight groups according to their sex, age and anxiety status. Locomotor activity was assessed in open field. Repeated anxiety tests were performed in elevated plus maze. Spatial learning and memory were evaluated with the Morris water maze. All behavioral tests were recorded online and analyzed offline with an analytical software. Exploratory behavior was lower in anxiety-induced rats. Male rats had lower anxiety levels, locomotor activity and exploratory behavior compared to females. During the training period of Morris water maze latency to find platform, total distance traveled and average swimming speed decreased in all groups with repeated tests and young rats generally were faster than aged rats. During the probe trial, although the number of platform crossings was not affected, time spent in the platform zone was higher in the young groups compared to the aged groups. In conclusion, age and sex affect locomotor activity, learning and memory in different aspects.

Role of curcumin in mesenteric ischemia - reperfusion injury in rats.

BACKGROUND: Curcumin is an antioxidant molecule that has been shown to attenuate ischemia/reperfusion (I/R) injury in several organ systems. In the present study, we aimed to evaluate the possible effects of curcumin on contractile response to agonists and histopathological alterations in rat esophagus subjected to mesenteric I/R. MATERIALS AND METHODS: Adult male Wistar albino rats were randomly allocated to 4 groups, namely group I: sham-operated animals (n=10); group II: animals subdued to I/R injury only (n=10) and laparotomy; 45 minutes of superior mesenteric artery ligation were followed by 2 hours of reperfusion, group III: curcumin/sham (n=10); 20 days before I/R, curcumin (200 mg/kg/) was administered by gastric gavage, and group IV: curcumin-I/R (n=10). Mesenteric ischemia/reperfusion model was generated by clamping the superior mesenteric artery for 45 min followed by reperfusion for 2 h. Oral administration of curcumin by gavage at a dose of 200 mg/kg/day lasted 20 days just before inducing the mesenteric ischemia. At the end of reperfusion period, all animals were sacrificed and esophagus samples were collected to assess the contractile response to agonists and histopathological alterations. RESULTS: Ischemia/reperfusion significantly decreased the contractile responses to carbachol and KCl and this decrease was attenuated by curcumin. Pretreatment with curcumin caused a remarkable decrease in histopathological parameters such as edema, congestion and inflammatory cells. CONCLUSIONS: The results of the present study demonstrate for the first time that curcumin can attenuate the esophageal injury associated with I/R (Tab. 4, Fig. 3, Ref. 32).

Effects of CoQ10 supplementation and swimming training on exhaustive exercise-induced oxidative stress in rat heart.

This study examined the combined effects of swimming training and coenzyme Q10 (CoQ10) supplementation on exhaustive exercise-induced oxidative stress in rat heart. The study was carried out with 4-month-old young adult male Wistar rats. Sixty four rats were divided mainly into two groups: trained and control. Each group was further divided into four subgroups: rest, exhausted, rest with CoQ10, exhausted with CoQ10. The training program consisted of swimming one hour each day, five days a week, for six weeks. At the end of sixth week, rats in exhausted exercise group were forced to swim until exhaustion and then they were immediately sacrificed, while rats in rest group were sacrificed at rest. Training alone or in combination with CoQ10 supplementation reduced to increasing MDA levels due to exhaustive exercise in rat heart (p<0.05). The trained-rest with CoQ10 group showed lower 8-OHdG levels than the control-rest with CoQ10 group. Exhaustive exercise effect was significant on SOD activity. Exhaustive exercise increased GSH levels in control groups while decreased GSH levels in training groups (p<0.05). In conclusion, the results suggest that CoQ10 supplementation combined with training may inhibit lipid peroxidation and DNA damage in the heart tissue. Also, it can be said that SOD activity and GSH levels were not influenced by CoQ10 supplementation (Fig. 4, Tab. 1, Ref. 69).

Curcumin increases vasodilatory effect of cilostazol in diabetic rat aorta.

Increased generation of oxidants and (or) reduced endogenous antioxidant defense mechanisms are associated with the etiology of diabetic vascular complications. The aim of the present study was to evaluate whether curcumin supplementation increases the vasodilatory effect of cilostazol in streptozotocin induced diabetic rat aorta. Cumulative addition of cilostazol caused concentration-dependent relaxations of thoracic aorta rings. The sensitivity and the maximal response to cilostazol were significantly higher in control than those in diabetic animals. Treatment with curcumin in control rats increased the sensitivity to cilostazol. Further, in aortic rings from diabetic rats treated with curcumin, the responses to cilostazol were significantly increased in comparison to the response in aorta from untreated diabetic rats. It can be conclude, that curcumin increases the cilostazol-induced vasodilation in diabetic rat aorta.

The role of nitric oxide on the responses of curcumin-treated rat aorta.

OBJECTIVES: The aim of the present study was to evaluate the influence of endothelial nitric oxide (NO) on the vascular responses of curcumin-treated rats. METHODS: The experimental groups included the control and curcumin-treated (200 mg/kg/day, p.o., for 4 weeks) group. The concentration response curves to receptor-dependent agent 5-hydroxytryptamine (5-HT; 10--3x10- M) and receptor-independent agent potassium chloride (KCl; 5-100 mM) were observed. RESULTS: The concentration response curves to 5-HT and KCl shifted to the right and the maximal response was significantly decreased in the curcumin-treated rat aortas. A pretreatment of rings with L-NAME (a NOS inhibitor, 10- M) increased both the sensitivity and maximal response to only 5-HT. No apparent histological changes were demonstrated in smooth muscle and connective tissue layers in the aortas of the control and curcumin-treated rat preparations. CONCLUSION: The results of the present study suggest that NO release from endothelial cells modulates curcumin-treated rat aorta responses to 5-HT, but not to KCl (Tab. 2, Fig. 4, Ref. 25).

Effects of treatment with coenzyme Q10 on exercised rat aorta.

In this study, the effect of long-term supplementation of coenzyme Q10 (CoQ10) on the responses of swim-trained rat aorta was investigated. Twenty-four adult male Wistar rats were divided into four groups: untrained, trained, untrained+CoQ10, and trained+CoQ10 group. In the trained groups rats swam for 60 min/day, five days/week for six weeks. The CoQ10 supplements were administered by intraperitoneal injection at a daily dose of 10 mg·kg-1 of body weight five days/week for six weeks. Swimming of the rats was performed in a container containing tap water. Rats were sacrificed and thoracic aortas were removed for ex vivo analysis after the last swimming session. The aortas were cut into rings 2.5 mm in length. Concentration-response curves for phenylephrine (PHE, 10-9-3×10-4 M) and potassium chloride (KCl, 5-100 mM) were isometrically recorded. The sensitivity and maximal responses to PHE and KCl of aortic rings obtained from trained rats were lower than those of untrained rats. CoQ10 supplementation decreased the responses to both vasoconstrictors in untrained and especially in trained groups. Although neither CoQ10 nor training did affect malondialdehyde (MDA) and protein carbonyl (PC) levels, creatine kinase (CK) activity decreased and superoxide dismutase (SOD) activity increased only with exercise training. Glutathione (GSH) levels increased in CoQ10 supplemented-untrained rats. In conclusion, our results suggest that CoQ10 supplementation may have beneficial effects during exercise.

Oxidative stress and antioxidant defense in plasma after repeated bouts of supramaximal exercise: the effect of coenzyme Q10.

AIM: The purpose was to determine the changes of oxidative stress and antioxidant markers in plasma after repeated bouts of supramaximal exercise and the effects of coenzyme Q10 supplementation on these changes. METHODS: This randomized, double blind, crossover study was composed of two 8-week periods of supplementation with either 100 mg.day(-1) CoQ10 or placebo. Fifteen healthy and sedentary men participated in the study. Five Wingate tests with 2 min rest between tests were performed. Blood samples were collected at rest, immediately after, 15 and 60 min after the fifth Wingate test for oxidative stress (malondialdehyde, nitric oxide, xanthine oxidase and adenosine deaminase) and antioxidant (superoxide dismutase, glutathione peroxidase and uric acid) markers. RESULTS: At baseline exercise session, malondialdehyde increased 15 and 60 min after the exercise compared to the rest and immediately after the exercise. Malondialdehyde at rest, immediately after and 60 min after the exercise decreased with coenzyme Q10 supplementation when compared to baseline. At baseline exercise session, uric acid increased 15 and 60 min after the exercise when compared to the rest. In conclusion, lipid peroxidation and antioxidant defense increase after repeated short-term supramaximal exercise. CONCLUSION: Coenzyme Q10 supplementation partially prevents the increase in lipid peroxidation after repeated short-term supramaximal exercise.

Alpha lipoic acid treatment improved endothelium-dependent relaxation in diabetic rat aorta.

The aim of this study was to ascertain the effects of α-lipoic acid (ALA) treatment on relaxant responses of acetylcholine (ACh) and isoprenaline (ISO) in aortic rings precontracted with serotonin (5-HT, 10(-6) M) obtained from streptozotocin (STZ)-induced diabetic rats. Diabetes was induced in the rats by 50 mg/kg streptozotocin (STZ) via an intraperitoneal injection. Rat body and aorta weights were measured. The isometric tension to ACh (10(-9)-3×10(-6) M) and ISO (10(-9)-10(-4) M) of 5-HT-precontracted diabetic and non-diabetic rat (control), diabetic-ALA-treated, and ALA-treated aortas, in organ baths were recorded. Six weeks after STZ treatment blood glucose was elevated compared to control rats. In aortic rings from diabetic rats ACh and ISO-induced relaxations were impaired whereas endothelium-independent relaxation to sodium nitroprusside (SNP) was unaffected. ALA (100 mg/kg/day) treatment for 5 weeks enhanced ACh and ISO-induced relaxation in diabetic aortas. This recovering effect was via NO because prevented by incubating the vessels with N(G)-nitro-L-arginine methyl ester (L-NAME, a NOS inhibitor). It may be assumed that ALA treatment in vivo, can protect against impaired vascular responsiveness in STZ-induced diabetic rats.

The dual effects of leptin on aortic rings with and without endothelium isolated from streptozotocin-induced diabetic rats.

The aim of this study was to examine the effects of leptin on aortic rings with and without endothelium isolated from streptozotocin (STZ)-induced diabetic and control rats, and also in the presence of an inhibitor of nitric oxide synthase (NOS). Thoracic aortic rings from 5-week STZ-induced diabetic (50 mg/kg i.p.) and age-matched control Sprague-Dawley rats were mounted in isolated tissue baths. Concentration-response curves to leptin (0.1 pM-1 nM) were constructed under basal tone and after precontraction with 1 microM phenylephrine in the presence or absence of Nomega-nitro-L-arginine methyl ester (L-NAME, 10 microM). Leptin caused a concentration-dependent relaxation of precontracted endothelium-intact aortic rings from control and diabetic rats. Responses to leptin in diabetic aorta were significantly increased compared to those of controls (P < 0.05). EC(50) values for leptin were similar for aortic rings from diabetic and control rats (P > 0.05). L-NAME pretreatment caused complete inhibition of the relaxant responses to leptin in the control aortic rings, while it induced a reduction in these responses in the diabetic rings (P < 0.05). Leptin-induced relaxation was eliminated when the endothelium was denuded. Leptin had no effect on the basal tone of endothelium-intact or -denuded aortic rings from control rats. In diabetic rings, leptin elicited concentration-dependent contractions (P < 0.05). Removal of the endothelium significantly increased the contractile effect of leptin on basal tone in diabetic rings (P < 0.05). The results suggest that leptin may induce vasodilatation by endothelial mechanism(s) other than nitric oxide (NO) release from the endothelium in diabetic aortic rings. On the other hand, leptin causes contractile effects on the basal tone in aorta smooth muscle isolated from STZ-induced diabetic rats. The contractile effect of leptin on basal tone may contribute to the development of hypertension in diabetes.

The ventilatory anaerobic threshold is related to, but is lower than, the critical power, but does not explain exercise tolerance at this workrate.

AIM: The aim of the present study was to investigate the relationships between critical power (CP), maximal aerobic power and the anaerobic threshold and whether exercise time to exhaustion and work at the CP can be used as an index in the determination of endurance. METHODS: An incremental maximal cycle exercise test was performed on 30 untrained males aged 18-22 years. Lactate analysis was carried out on capillary blood samples at every 2 minutes. From gas exchange parameters and heart rate and lactate values, ventilatory anaerobic thresholds, heart rate deflection point and the onset of blood lactate accumulation were calculated. CP was determined with linear work-time method using 3 loads. The subjects exercised until they could no longer maintain a cadence above 24 rpm at their CP and exercise time to exhaustion was determined. RESULTS: CP was lower than the power output corresponding to VO2max, higher than the power outputs corresponding to anaerobic threshold. CP was correlated with VO2max and anaerobic threshold. Exercise time to exhaustion and work at CP were not correlated with VO2max and anaerobic threshold. CONCLUSIONS: Because of the correlations of the CP with VO2max and anaerobic threshold and no correlation of exercise time to exhaustion and work at the CP with these parameters, we conclude that exercise time to exhaustion and work at the CP cannot be used as an index in the determination of endurance.

Treatment with antidepressive drugs improved quality of life in chronic hemodialysis patients.

BACKGROUND: Despite some improvements in dialysis therapies, depression still remains an important problem in chronic hemodialysis (HD) patients. In this study, we aimed to investigate the association of depression and its treatment with quality of life (QOL) in HD patients. PATIENTS AND METHODS: 97 HD patients (52 male, 45 female, mean age 55 +/- 16 years) were enrolled. All patients had been dialyzed for more than 6 months. In order to evaluate QOL of the patients, a short form of Medical Outcomes Study (SF-36) was used. Depression was assessed by using Beck Depression Inventory (BDI). Patients who had BDI score > or = 15 were diagnosed as to have depression. Patients with depression received antidepressive treatment (sertralin HCl, 50 mg/day) for an 8-week period. After 8-week antidepressive treatment, all biochemical analysis, SF-36 and BDI were performed again. RESULTS: 40 patients (20 male, 20 female, mean age 56 +/- 14 years) had depression. All parameters related to QOL were significantly decreased in patients with depression as compared to patients without depression. Severity of depression was correlated with QOL parameters. After 8 weeks of treatment, as parallel to changes in BDI, QOL parameters improved in patients with depression. CONCLUSION: Decrease in QOL, associated with depression and antidepressive treatment, improves QOL in HD patients. Hemodialysis patients should be followed-up closely for presence of depression. Treatment of depression with antidepressive drug regimen would lead to relieve the symptoms related to depression and improvement of QOL in these patients. Antidepressive treatment should be required more often than we prescribe in routine clinical practice now.

Evaluation of the association between null genotypes of glutathione-S-transferases and Behcet's disease.

Glutathione S-transferases (GST) play an important role in oxidative stress related syndromes. An imbalance of the oxidant and antioxidant systems is important in the pathogenesis of Behcet's disease (BD). The objective of this study was to evaluate the association of null genotypes of GST-M1 and GST-T1 with BD since some preliminary molecular genetic data were recently published. Ninety-four Turkish BD patients (42 male, 52 female, 37.1+/-10.4 years) and 140 healthy volunteers (70 male, 70 female, 36.8+/-11.7 years) matched for age and gender with the patients as the control group were included in the study. Distributions of GST-M1 and GST-T1 genotypes were determined by multiplexed PCR using three sets of primers for GST-M1, GST-T1, and beta-globulin genes. There was no association between BD and the frequencies of GST-M1 and GST-T1 null genotypes when compared to controls by separate analysis. However, by cross and pooled combination analysis there was a significant association between the frequencies of pooled GSTs with one or both null genotypes in BD and controls. This is the first evidence that the association between the frequencies of GST-M1 and GST-T1 null genotypes and BD might be dependent on the interaction of multiple null allele polymorphisms rather than a single null allele of GST-M1 and GST-T1.

The effects of creatine supplementation on performance during the repeated bouts of supramaximal exercise.

AIM: The aim of this study was to investigate the effects of creatine supplementation on performance during the repeated bouts of supramaximal exercise. METHODS: Twenty-three untrained young males participated in the study. A double blind design was used to create the creatine and placebo groups. Wingate test was performed 5 times with 90 g x kg(-1) body weight load with 2-min intervals. Peak power, mean power (MP), fatigue index (FI) were calculated. Capillary blood samples for lactate analysis were taken during the initial rest period and soon after the fifth Wingate test. For 6 days the creatine group (n=12) ingested 5 g creatine monohydrate, the placebo group (n=11) a flavored drink without creatine monohydrate 4 times daily. On the 7th day, the Wingate tests were repeated, as was the 1st day. RESULTS: In the creatine group, MP in the 3rd and 4th Wingate test, in the placebo group FI in the 1st and 2nd Wingate test significantly increased. While the total power output obtained from the five Wingate tests increased 7.6% from 366.3+/-65 W to 394+/-67.1 W, there was no change in the placebo group. CONCLUSIONS: It is concluded that creatine supplementation enhances total power output during the repeated bouts of supramaximal exercise separated by short resting intervals.

The relationship between HRCT and pulmonary function in Behcet's disease.

The purpose of this study was to compare the pulmonary functions in female Behcet's patients with or without pathological pulmonary lesions using high resolution computerized tomography (HRCT). Twenty-nine female patients aged 19-54 yrs and 20 healthy females aged 19-50 yrs (control group) were accepted into the study. HRCT images were taken and according to HRCT patients were divided into HRCT (+) and HRCT (-) groups (18 patients in each). Pulmonary function tests (PFT) through a spirometer were performed and FVC, FEV(1), FEF(25-75%), PEF, VC, RV, FRC, DLCO and DLCO/VA were determined. No statistically significant difference was observed when the PFT values were compared between HRCT (+) and HRCT (-) patients for the obtained results and the percentage of the expected values. When the PFT values were compared for both HRCT (+) and HRCT (-) patients with the control group separately there was no statistical difference between the best values. A statistically low DLCO/VA value was observed between the percentage of the expected values. It is concluded that though there is a pulmonary restriction in Behcet's disease, this restriction has no relation to pulmonary functions. It would be useful to perform pulmonary function tests in the patients with Behcet's disease both with or without any pathological findings in HRCT for obtaining information about pulmonary functions. We suggest that even when the results of the pulmonary function tests are normal, considering some pathological changes in HRCT, HRCT investigations may be useful for following up the disease.

Basal metabolic rates of Turkish women during pregnancy.

The purpose of the present study was to investigate the basal metabolic rates (BMRs) of pregnant Turkish women and to compare them with values from other countries. Twenty-four pregnant women (aged 24.8+/-5.7 years) were studied longitudinally from early pregnancy through to the end of pregnancy. BMR values were measured in the 1st, 2nd and 3rd trimesters by indirect calorimetry. While the measured BMR significantly increased (279+/-212 kcal/day between the 1st and 3rd trimesters), no change was found when BMR was expressed per unit of body weight. BMR in the 2nd and 3rd trimesters showed a significant correlation with body weight. The BMR increase in pregnant Turkish women was close to that reported in developed countries, and higher than that reported in developing countries. Knowing the metabolic changes of the pregnant women may contribute to dietary recommendations for them.

A combined method for estimating ventilatory threshold.

BACKGROUND: The aims of this study were to compare two new methods (Dmax and CUSUM) for determination of the ventilatory threshold and to examine the consequences of estimation by application of these methods in combination. EXPERIMENTAL DESIGN: a comparative design was used. SETTING: the study was performed in the Exercise Physiology Laboratory in the Faculty of Medicine, Selçuk University. PARTICIPANTS: thirty-two untrained males (20.6 +/- 1.2 yrs) performed an incremental exercise test on a cycle ergometer. INTERVENTIONS: there is no intervention. MEASURES: ventilatory and gas exchange variables were measured breath-by-breath. The ventilatory thresholds were detected by conventional linear regression, CUSUM, Dmax and combined CUSUM-Dmax methods. RESULTS: The ventilatory thresholds determined by Dmax method gave the highest r-values compared to the criterion method. There was no statistical difference between thresholds determined by all methods or by the same method using different variables. Ventilatory thresholds could not be determined by the conventional linear regression method in three subjects but were determined in all subjects by the other three methods. CONCLUSIONS: Although all methods presented in this study can be used in the determination of ventilatory threshold, the Dmax method was found to be the most valid one. When using the CUSUM method, combining it with the Dmax method increases the validity of the measurement.