Date of Award

Summer 8-1-2002

Document Type

Thesis

Degree Name

Master of Arts (MA)

Department

Physical Education

First Advisor

Jeffrey E. Edwards

Second Advisor

J. P. Babington

Abstract

Motoneuron pool excitability as measured by the Hoffinann reflex (H-reflex) in endurance-trained subjects has been shown to differ from their untrained counterparts. Further, the effects of endurance training on the H-reflex are equivocal. Objective: To determine if differences exist in the motoneuron pool excitability of the soleus in highly trained endurance athletes due to the effect of endurance training. Design: A 2 X 3 factorial design with repeated measures. Setting: This study took place in the Exercise Physiology Laboratory located in the Health and Human Performance Building on the Indiana State University campus. Subjects: Eleven male cross-country team members (XC; mean± sd, age: 19.7 ± 1.2 yr; Ht: 152.68 ± 6.6 cm; Mass: 64.7 ± 5.9 kg; VO2 max: 66.4 ± 4.8 m1·1 ·kg· min"1 ) and thirteen active male controls (Control; age: 20.3 ± I. 7 yr; Ht: 155.32 ± 6.38 cm; Mass: 78.1 ± 10.4 kg; VO2 max: 50.5 ± 4.1 m1·1 •kg· min"1 ). Measurement: Supine H-reflex testing on the soleus. The H-reflex and M-response were measured at the beginning of the cross-country season (Tl), at the peak of the crosscountry training program (T2) and at the taper portion of the cross-country training program (T3) as reported by the coaches. Results: There was a significant difference in soleus HIM (F2,20=7.69, p=0.003) between the thr~e training periods for the crosscountry subjects. There was also a significant difference in the soleus H: M (F1, 10=8.99, p=0.013) from pre-training to end training and (F1, 10= 14.86, p=0.003) from pre training to peak training. No differences were observed in the Control group's soleus H: M. Conclusion: An increase in training volume decreases the H-reflex of the soleus in male cross-country runners.

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