Influence of type II muscle fibers and creatine supplementation on repeated bouts of the Wingate Anaerobic Test
Poirier, Marc Andre, 1974-
Master of Science
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The main purpose of this thesis was to investigate the influence of muscle fiber type composition and supplemental creatine monohydrate on repeated bouts of the Wingate Anaerobic Test (WAnT). More specifically, would a higher percentage of Type II muscle fibers demonstrate a greater significant improvement in repeated bouts of cycle ergometry after creatine supplementation. Nineteen males (mean ± SD age, body mass, and height = 21.7 ± 1.9 yr., 84.1 ± 14.1 kg and 161.5 ± 7.8 cm, respectively) participated in the 13 day experiment. Initially, sixty-five participants performed a single 30-s WAnT against a resistance of .10 kg/kg body weight. All scores were then rank ordered from highest to lowest, according to relative peak anaerobic power (PAPr) scores. Ten participants from both ends of this distribution were approached and requested to volunteer for the remainder of the study. This allowed the following four groups to be constructed: 1) high WAnT with creatine (n = 5), 2) high WAnT with placebo (n = 5), 3) low WAnT with creatine (/i = 5), and 4) low WAnT with placebo (n = 4). On days 4 and 12 of the study, percutaneous muscle biopsies were obtained from the vastus lateralis and stained histochemically to determine fiber type distribution (Type II, IIa, and Ilb). This data demonstrated a positive, but weak relationship between peak anaerobic scores (relative) obtained during the single 30-s WAnT and percent type II muscle fibers (r = 0.52, p<0.05). Furthermore, a Spearman rank-order correlation revealed a positive monotonic relationship (R = 0.611, p<0.01) between the variables. Finally, a 2 x 2 factorial ANOVA (F (1,15) = 12.8, p<0.01), revealed that the 10 participants within the high PAPr group had higher values for %FT, regardless of treatment. This data revealed that the grouping of participants according to PAPr during the single 30-s WAnT was reflective of their fiber type distribution in regards to percent type II muscle fibers. Five repeated bouts of the WAnT were performed on days 5 and 12 of the study, with each bout lasting 15-s, against a resistance o f0.075 kg/kg body weight and with 45-s of active rest between each bout. Supplementation occurred on days 7 through 11, with groups # 1 and #3 receiving the treatment (4 x 5g of creatine + 2g of dextrose powder) and groups # 2 and # 4 receiving the placebo (4 x 7g of dextrose powder). Peak anaerobic power (absolute and relative), mean anaerobic power (absolute and relative) and percent power decrease were recorded during each of the five bouts. The design was a 2 (time: pre or post) by 2 (treatment: creatine or placebo) by 2 (WAnT: high or low) by 5 (bouts; 1 through 5) split-plot factorial analysis. Change scores were calculated for all five dependent measures and consequently the data was analyzed with a 2 (treatment; creatine or placebo) by 2 (WAnT: high or low) by 5 (bouts: 1 through 5) split-plot factorial ANOVA, which revealed no significant main or interaction effects. Furthermore, there was a significant increase in body weight, from pre to post-supplementation, regardless of treatment. The results therefore, suggest no relationship between participants' fiber type distribution (through the stated relationship to PAPr), creatine supplementation, and repeated bouts of the WAnT. However, due to the small number of participants per cell or group within this study, the results should be viewed with caution.