Honors Theses

Date of Award

2019

Document Type

Undergraduate Thesis

Department

Health, Exercise Science, and Recreation Management

First Advisor

Ling Xin

Relational Format

Dissertation/Thesis

Abstract

The contralateral repeated bout effect (CL-RBE) is known as a protective effect in which an initial bout of eccentric exercise reduces muscle damage in the contralateral limb after a similar bout of eccentric exercise. To our knowledge, previous studies on CL-RBE only recruited males or a mixture of both sexes. PURPOSE: To investigate the presence of the CL-RBE of the elbow flexors in women. METHODS: Twelve healthy women (20.9 ± 2.5 years) performed two bouts of 45 maximal eccentric contractions (ECC) of the elbow flexors using the opposite arm separated by 14 days. The isokinetic muscle strength (60°/sec) was measured pre-exercise, immediately post-exercise, and 24 and 48 h post-exercise. Limb girth, range of motion (ROM), and muscle soreness were measured pre-exercise, and at 24 and 48 h post-exercise. Surface Electromyography (EMG) was recorded during both exercise bouts from the biceps brachii muscle. Data of all variables were analyzed using two-way repeated measures ANOVA (Bout × Time) except that of EMG amplitude and median frequency (MF), which was analyzed via paired t-test. RESULTS: The isokinetic strength was significantly reduced after the eccentric exercise for both bout 1 (-19.3 ± 17.4%, P < 0.01) and bout 2 (-15.3 ± 15.2%, P < 0.01). Significant main effects of time were also observed for muscle soreness and ROM. Limb girth, EMG amplitude, and MF did not change significantly (P > 0.05) after either exercise bout. There were no significant differences between bouts for all the measured variables. CONCLUSION: The CL-RBE of elbow flexors was not evident in young healthy women. This was probably because the initial bout of exercise did not induce enough damage to bring about the CL-RBE in the second bout or the CL-RBE in women lasted shorter than two weeks.

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