The blood antioxidant defence capacity during intermittent hypoxic training in elite swimmers.

The main objective of this study was to examine the chronic effect of simulated intermittent normobaric hypoxia on blood antioxidant defence capacity in swimmers. The study included 14 male and 14 female competitive swimmers performing part of land training under simulated intermittent normobaric hypoxia (O2 = 15.5%) or in normoxia. Land interval training took place twice per week, with a total of 8 training units during the study, performed with individualized intensity. The activities of blood antioxidant enzymes did not change significantly during the first and last training unit in the hypoxic and normoxic group. However, when comparing individual variables a significant effect of exercise was observed on GPx an CAT activities, whereas training units significantly differentiated GPx and GR activities. The oxygen conditions and gender had a significant influence on CAT activity. The total antioxidant capacity was not significantly affected. Only in male swimmers from the hypoxic group did the training significantly increase resting levels of MDA. In conclusion, training in normobaric hypoxia was not an adequate stimulus for the excessive response of the antioxidant defence system, despite increased oxidative stress in these conditions.

Blood antioxidant status in road cyclists during progressive (VO2max) and constant cyclist intensity test (MLSS).

AIM: The aim of the study was to evaluate the effect of two different cycling intensities on the blood antioxidant status in seven road cyclists male (M) (age 25.6±4.9 years; height 1.8±0.0 m; body mass 72.4±3.4 kg, and VO2max 66.8±8.9 mL*kg-1*min-1) and six road cyclists females (F) (age 26.5±2.5 years; height 1.67 ±0.01 m; body mass 56.5±5.3 kg; and VO2max 57.2±4.1 mL*kg-1*min-1). METHODS: The experiment was carried out with two tests: a progressive test (VO2max) (TP), and a 30-minute submaximal steady state test (TMLSS). The activity of superoxide dismutase, catalase (CAT), glutathione peroxidase, glutathione reductase, and creatine kinase, and the concentration of uric acid, reduced glutathione, malondialdehyde (MDA), blood lactate as well as total antioxidant potential, were assayed. RESULTS: Exercise significantly differentiated the activity and level of antioxidants. In both tests, after exercise a significant increase of CAT (P≤0.05) and CK (P≤0.05) activity was observed, as well as MDA (P≤0.05) level. CONCLUSION: It was demonstrated that neither the type of test (TP, TMLSS) nor the sex of the subjects exerted significant influence upon the activity of antioxidant enzymes and the level of low molecular weight antioxidants. Due to the workload in road cycling, where an average race or stage lasts a few hours, the 30-minute test was probably too weak a stimulus for the organism to disturb the pro- and antioxidative homeostasis.

The effects of sprint (300 m) running on plasma lactate, uric acid, creatine kinase and lactate dehydrogenase in competitive hurdlers and untrained men.

BACKGROUND: High intensity exercise may induce muscle damage especially in individuals unaccustomed to regular physical efforts. Our aim was to compare the impact of 300 m sprint running on muscle enzymes release into blood in competitive hurdlers and untrained but physically fit adults. EXPERIMENTAL DESIGN: Comparative study. SETTING: General community. PARTICIPANTS: Nine competitive hurdlers (CH; 21.3 yrs+/-3.1) and six matched moderately active untrained men (UT). INTERVENTIONS: Subjects performed a single 300 m sprint running test. MEASURES: Plasma creatine kinase (CK) and lactate dehydrogenase (LD) activities, and concentrations of lactate (LA) and uric acid (UA) measured before the warm-up and 5 min, 2 and 20 hrs postrun. RESULTS: Mean runner performance achieved by CH was significantly better (35.53-s+/-0.64) and LA concentrations significantly higher (14.95 mM+/-0.59) than those recorded in UT (41.52-s+/-2.22; 10.13 mM+/-0.59). Pre- and postrun CK activities until the 2nd hour of recovery were found to be significantly higher (p<0.05) in CH than in UT, whereas LD activities were similar in both groups pretest, but significantly higher in UT immediately postrun. In CH, the highest CK activity (32 percent increase) was recorded immediately post-test, whereas in UT the peak CK (135 percent increase) was attained in the 20th hour of recovery. In both groups UA reached the peak level in the 2nd hour of recovery. CONCLUSIONS: More pronounced and delayed postrun increase in CK, as recorded in UT, may provide evidence of a larger exercise-induced muscle injury in the untrained adults. Higher postexercise UA levels as recorded in CH might account for a more marked involvement of adenylate kinase reaction in ATP resynthesis.