ABSTRACT
The purposes of this study were to determine whether acute resistance exercise increases serum malondialdehyde (MDA) levels postexercise, and if so, whether resistance exercise training status influences the magnitude of the exercise-induced lipid peroxidation response. Twelve recreationally resistance-trained (RT) and 12 untrained (UT) men who did not have resistance exercise experience in the past year participated in this study. All subjects completed an 8-exercise circuit resistance exercise protocol consisting of 3 sets of 10 repetitions at 10 repetitions maximum for each exercise. Blood samples were obtained pre-exercise, at 5 minutes postexercise, and at 6, 24, and 48 hours postexercise. At pre-exercise, MDA (nmol.ml(-1)) averaged 3.41 +/- 0.25 (RT) and 3.20 +/- 0.25 (UT) and did not differ (p > 0.05) either between groups or over time. Creatine kinase (IU.L(-1)) was significantly (p < 0.05) elevated 5 minutes postexercise (170.6 +/- 25.8), 6 hours postexercise (290.3 +/- 34.4), 24 hours postexercise (365.5 +/- 49.9), and 48 hours postexercise (247.5 +/- 38.5) as compared with pre-exercise (126.4 +/- 20.2) for both groups. There was no difference (p > 0.05) in CK activity between groups. This study indicated that moderate-intensity whole-body resistance exercise had no effect on serum MDA concentration in RT and UT subjects.
Subject(s)
Malondialdehyde/blood , Physical Education and Training/methods , Physical Fitness/physiology , Adult , Creatine Kinase/blood , Cross-Sectional Studies , Humans , Lactic Acid/blood , Lipid Peroxidation/physiology , Male , Students , Time Factors , UniversitiesABSTRACT
PURPOSE: An estimation and production paradigm was used to determine whether clinically normal 8- to 12-yr-old female (N = 18) and male (N = 18) children could (a) self-regulate intermittent cycle ergometer exercise using a prescribed target rating of perceived exertion (RPE), (b) discriminate between target RPEs, and (c) produce intermittent target RPEs in both an ascending and descending sequence. METHODS: Overall body RPE was assessed with the Children's OMNI Scale (0-10). Subjects underwent (a) one orientation trial, (b) one estimation (E) trial, and (c) two production (P) trials. During E, RPE was estimated each minute of a progressive cycle ergometer test. During the 3-min intermittent P trials, subjects titrated cycle brake force to produce either an RPE sequence of 2 and 6 (ascending) or 6 and 2 (descending). The P trials simulated short, intermittent exercise typical of children's play. RESULTS: Oxygen uptake (VO2) did not differ between E and P at a target RPE of 2 (0.63 versus 0.66 L x min(-1)) and 6 (1.27 vs 1.21 L x min(-1)). Heart rate (HR) did not differ between E and P at a target RPE of 2 (104.1 vs 102.6 beats.min-1) and 6 (153.7 vs 154.5 beats x min(-1)). Both VO2 and HR were higher (P < 0.01) at a target RPE-6 than -2. Responses were not affected by gender or production sequence. CONCLUSION: Young female and male children were able to use the OMNI Scale to self-regulate short-duration intermittent cycle exercise intensity.
