METABOLIC FACTORS INFLUENCING FATIGUE DURING A 90 SECOND MAXIMUM MUSCLE CONTRACTION

by DAVID C. TUCKER

GARY R. HUNTER, COMMITTEE CHAIR JOHN P. MCCARTHY BRADLEY R. NEWCOMER

Submitted to the graduate faculty of The University of Alabama at Birmingham, in partial fulfillment of the requirements for the degree of Master of Arts in Education BIRMINGHAM, ALABAMA 2009

METABOLIC FACTORS INFLUENCING FATIGUE DURING A 90 SECOND MAXIMUM MUSCLE CONTRACTION DAVID C. TUCKER EXERCISE PHYSIOLOGY ABSTRACT The purpose of this study was to examine muscle metabolites that affect fatigue in a 90s maximum muscle contraction.

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P-Magnetic Resonance Spectroscopy was used to

determine the concentration of inorganic phosphate (Pi), phosphocreatine (PCr), adenosine triphosphate (ATP) and phosphomonoesters (PME) in the triceps surae while subjects performed isometric plantar flexion for 90s at maximum voluntary contraction (MVC). Fifty four women were dichotomized from the fatigue index (Forceend – Forcepeak), with subjects below the 40th percentile classed as fatigue prone (n = 21) and subjects above the 60th percentile classed as fatigue resistant (n = 23) individuals. Time course changes in high energy phosphates were used to model creatine kinase (CK), anaerobic glycolysis (AnGly), oxidative phosphorylation (OxPhos), pH, metabolic economy (ME), adenosine diphosphate (ADP), and adenosine monophosphate (AMP). A 2(group) x 7(time) repeated measures ANOVA on time points 1, 15, 29, 43, 57, 71, 85 seconds was used to assess differences between groups over time. ME and OxPhos were calculated at the end of the 90s MVC with differences between groups assessed by Independent samples t-tests. ME in Nonfatiguers was 45% higher than fatiguers (p