Date of Award

2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Education

Abstract

Regular unilateral resistance training of an exercising limb has been shown to induce strength gain in both the exercised limb and the contralateral, unexercised limb. This phenomenon is called cross-education. Recent evidence has suggested that unilateral training combined with mirror training, practiced by imposing a reflective image of the exercising limb over the resting limb, may enhance the strength increase transferred from the trained limb to the untrained limb. However, this evidence has only been shown to occur in small, distal muscles within the forearm. The purpose of this study was to determine whether four weeks of unilateral resistance training with a mirror augmented the cross-education effect within the biceps brachii by assessing changes in maximal, isometric biceps strength, biceps activation and triceps antagonistic activation. Six healthy, non-strength trained adult participants were randomly assigned into the mirror training group (n = 3; age = 27 ± 5 yrs.) and the non-mirror training group (n = 3; age = 25 ± 3 yrs.). Maximal voluntary isometric contractions (MVICs) measured with a Dillon Strain gauge were used to assess changes in the trained and untrained biceps strength across five weekly assessments (ex. Pre-, Week 2, Week 3, Week 4, and Post-assessment) throughout the four-week program. Surface electromyography (sEMG) was recorded during bicep MVICs on each arm using a Delsys TRIGNOTM wireless system to assess changes in biceps and triceps activation across the four-week program in the trained and untrained arms. Each week of the program contained three exercise sessions consisting of three working sets of ten repetitions of dumbbell curls for the right arm only. A One-way ANOVA was conducted for the trained and untrained arms between the mirror training group and non-mirror training group at .05 level to determine if there were any significant differences between biceps MVIC, biceps sEMG and triceps EMG from pre- to post-assessment. The means and standard deviations of each variable were calculated, and a qualitative analysis of the results was used to compare the mirror and non-mirror groups. Further, biceps electrical efficiency was calculated to evaluate the contributions of neurological adaptations involved in the changes associated with MVIC both arms of the mirror and non-mirror group. There were no significant differences between the mirror group and non-mirror group in biceps MVIC, biceps sEMG, or triceps EMG in either the trained or untrained arms. This lack of significance may be attributed to the small sample size used in this study (n = 6). Mirror group biceps MVIC was shown to increase in the trained and untrained limbs by 5.2 kg (22% of initial strength) and 4.3 kg (24% of initial strength), respectively. Non-mirror group biceps MVIC was shown to increase in the trained and untrained limbs by 5.13 kg (19% of initial strength) and 4.5 kg (23% of initial strength), respectively. Mirror group trained and untrained biceps sEMG both shown increasing trends across the five weekly assessments, while the untrained arm of the non- mirror group showed an increasing trend from the pre-assessment to the week four. Non-mirror group trained biceps sEMG presented no trends in the trained arm and a steady increase from week three to post-assessment in the untrained arm. Training had no noticeable effects on triceps or antagonistic activation during biceps MVIC. Despite the limitations, this study affirmed that the biceps unilateral training paradigms used in this study may be effective in enhancing strength in the trained and untrained biceps within its sample. Further studies with greater sample sizes are needed to investigate the differences between mirror and non-mirror unilateral training on MVIC, and agonist and antagonist muscle activation.

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