Document Type

Thesis

Degree Name

Master of Kinesiology (MKin)

Department

Kinesiology and Physical Education

Faculty/School

Faculty of Science

First Advisor

Dr. Michael Cinelli

Advisor Role

Supervisor

Second Advisor

Dr. Jayne Kalmar

Advisor Role

Supervisor

Abstract

Downslope walking (DSW) has been proposed as a rehabilitation tool for people with Multiple Sclerosis (PwMS) although there are mixed findings in young adults (YA) regarding the balance control changes, despite both populations experiencing depressed spinal motor neuron (MN) pool excitability. Our aim was to determine whether YAs could demonstrate improved balance control in conjunction with SOL H reflex depression (estimate of spinal MN excitability) following DSW. We also aimed to determine whether reciprocal inhibition was a potential mechanism for H reflex depression via conditioned SOL H reflexes. Thirty young adults (23±1.4y, 6 males) were assigned to 30-minutes of DSW (-10°) or LW (0°) on a treadmill. Pre- and post-testing included 1) 10 behavioral trials with 30-s quiet standing on a force plate and 3 steps, alternating trials with eyes open (EO) and closed (EC); 2) SOL H reflex recruitment curves, generated by tibial nerve stimulation, and conditioned H reflexes elicited by stimulating the peroneal nerve prior to the tibial nerve. Only dynamic balance control measures changed following DSW and are presented as the change from pre-test values. There was an interaction between group and vision on Margin of Stability in AP (MOSAP), step length (SL), and ML COM variability. With EO, DSW decreased SL (-2.9 ± 4.9%) and MOSAP (-10.3 ± 13.6%), and increased ML COM variability (6.4 ± 8.3%). However, DSW exhibited similar changes to LW when performing the task with EC: minimal change in SL (1.3 ± 8.2%) or MOSAP (0.2 ± 13.7%), and decreased ML COM variability (-15.1 ± 31.9%). Balance changes occurred with SOL H reflex depression (-46.9 ± 15.4%) but there was no increase in reciprocal inhibition.Overall, DSW may not be beneficial to balance control in YA, which opposes findings in PwMS.

Convocation Year

2020

Convocation Season

Spring

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