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MUSCLE DAMAGE CAUSED BY PRIOR EXERCISE AND HYPOHYDRATION

1999; Lippincott Williams & Wilkins; Volume: 31; Issue: Supplement Linguagem: Inglês

10.1097/00005768-199905001-00741

1530-0315

L. J. Svetkey, Roger A. Fielding, Deborah Riebe, Linda S. Lamont, Arthur C. Cosmas, Thomas G. Manfredi,

Body Composition Measurement Techniques

742 The purpose of this study was to quantify Z-band damage following exercise induced damage in dehydrated vs hydrated muscle. Twenty-four healthy young males, ages 18 to 30 years, were randomly assigned to one of three groups: dehydration (DEH), hydration (HYD), and control (CON). A cross-sectional study design was employed. DEH and HYD subjects exercised for 2 hours on a cycle ergometer at 57% of their V02max, receiving no fluids (DEH) or 7.5 ml per kg of body weight of a 5% carbohydrate-electrolyte beverage (Gatorade) every 30 minutes (HYD). All subjects performed 10 sets of 10 repetitions per set of eccentric only quadriceps exercise of both legs at 100% of their individually determined concentric one repetition maximum. Core temperature and sweat losses were measured. Percutaneous needle biposy specimens of the vastus lateralus were taken before cycling for the DEH and HYD subjects and before eccentric exercise for the CON group. Biopsies were also taken immediately after and 3 days after the eccentric exercise from all three groups. Stereological measurements of volume densities of Z-bands and damaged Z-bands were made using a 100 point isotropic semicircular grid. Examination of electron micrographs of muscle samples from 5 subjects per group showed a 2-fold increase in Z-band damage immediately following eccentric exercise in all 3 groups (p<0.001) and remained elevated 3 days after exercise. There was no difference in magnitude of Z-band damage after exercise in all 3 groups. These data suggest that eccentric exercise is associated with prolonged Z-band damage and ultrastructural features which may be unique for hydrated vs dehydrated subjects.