Health, Exercise, and Sports Sciences ETDs

Publication Date

7-3-2012

Abstract

The purpose of this dissertation was to identify the effect of creatine (Cr) supplementation during immobilization on muscle performance. Twenty-five healthy, active male (n = 14; age 28 ± 5 years) and female (n = 11; age 22 ± 4 years) subjects performed wrist flexion exercise before (PRE) and after (POST) one week of wrist/forearm cast immobilization. During the immobilization period, subjects consumed Cr (20g) or placebo PL (4% CHO flavored solution) interspersed throughout the day. On the first day of immobilization subjects consumed two doses of Cr (10 g) or PL. Subjects consumed 5 g of Cr or PL on four occasions from day 2 to day 7 for a total of 20 g•d-1. On day 8, subjects were instructed to consume a total of 5 g CR or PL, and the cast was removed prior to POST test. Exercise was performed on a custom developed rotational ergometer device attached by a cord to suspended weights across a wall pulley. Wrist flexion exercise commenced with an incremental protocol to fatigue followed by a 4.8 min rest. Then constant-load exercise (CL1) was performed with the peak weight achieved in the incremental protocol for 2.4 min, followed by another 4.8 min rest. The second constant-load exercise bout (CL2) used the same weight as CL1 for a final 2.4 min endurance exercise bout. Total work and average power was quantified by the kg load, the distance the weight was lifted, and the time to conduct the work. Immobilization caused a significant decrement in forearm total work (-3.17 ± 2.27% PL; -2.61 ± 1.89% CR) and average power (-3.43 ± 2.35% PL; -2.61 ± 1.89% CR) during the incremental protocol, regardless of Cr supplementation. During the first CL bout, both total work and average power decreased in PL after immobilization (-28.9 ± 9.63%; p < 0.05), but not in CR. However, during CL2, both total work and average power decreased in CR (work -14.39 ± 4.54%; power -10.52 ± 4.6% and PL (work -21.98 ± 8.28%; power -21.3 ± 8.25%) groups after immobilization. The significance of these findings are; 1) 7 days of wrist immobilization will significantly decrease wrist flexion work and power, 2) this decrement can be slowed with Cr supplementation for an initial constant load exercise bout performance, and 3) however, this beneficial effect may be lost with repeated bouts of constant load exercise. Future research should help elucidate the underlying mechanisms of fatigue after immobilization to explain possible differences in incremental and constant load endurance exercise performance.

Keywords

Casting, Creatine, Muscle Endurance

Document Type

Dissertation

Language

English

Degree Name

Physical Education, Sports and Exercise Science

Level of Degree

Doctoral

Department Name

Health, Exercise, and Sports Sciences

First Advisor

Kravitz, Len

First Committee Member (Chair)

Schneider, Suzanne

Second Committee Member

Conn, Carole

Third Committee Member

Mermier, Christine

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