Initial development of a method to quantify ankle force perception in young adults Öffentlichkeit

Evans, Claire (Spring 2023)

Permanent URL: https://etd.library.emory.edu/concern/etds/qz20st917?locale=de
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Abstract

Background: Force perception is comprised of two primary inputs: sensory feedback and the motor command. Currently, force perception has only been assessed in the upper limb, which has shown a trend of overestimating when trying to reproduce low forces and underestimating when trying to reproduce high forces. Additionally, the ability of persons to reproduce brief non-voluntary wrist force contractions due to muscle stimulation was found to be poor. Little is known about force perception in the lower limb, but force perception is likely important for lower limb behaviors like ankle propulsion when walking.

Objective: The goal of this study is to develop a method to quantify ankle force perception and use this method to distinguish the roles of force-related feedback and the motor command in force perception. Our three objectives include characterizing force matching ability at five force levels in able-bodied adults, evaluating learning effects within session and across days, and examining force matching with the reference force arising from muscle stimulation.

Methods: A force matching paradigm was used with eight young, able-bodied subjects. All eight subjects participated in two days of ankle plantarflexion voluntary force matching at five force targets determined from their maximum plantarflexion contraction force. Four of the subjects also participated in force matching with the reference force arising from muscle stimulation of the gastrocnemius and soleus causing a non-voluntary plantarflexion twitch contraction at two targets forces.

Results: Force matching error was low across all target forces, and error did not significantly differ between forces. Minimal learning occurred across days and within day across trials. Force matching with stimulation did not appear to differ from voluntary force matching.

Conclusion: Overall, this is the first feasible method for assessing lower limb force matching at the ankle. Eight trials are sufficient to characterize force matching ability in the lower limb. Results indicate that lower limb force perception likely differs in some ways from upper limb force perception.

Table of Contents

Introduction and Background……………………………………………………..……………….….……1

Hypothesis……………………………………………………..…………………………………….…..........4

Methods……………………………………………………..……………………….....……………….….….4

Results……………………………………………………..………………………………….….....……...…11

Discussion……………………………………………………..……………………………………......….…12

Tables and Figures………………………………………..…………………………………………....….…18

Figure 1: A sketch diagram illustrating the combination of sensory feedback and the motor command that comprises force perception 18

Table 1: Subject participation details and order of target forces during experiment 19

Figure 2: Experimental setup and voluntary force matching 20

Figure 3: Force matching with stimulation 21

Table 2: MVIC values of each subject for each day of force match testing used to calculate target forces 22

Figure 4: VE values of day 1 and day 2 reference and match forces 23

Table 3: Objective 1 data 24

Figure 5: Objective 1 data 25

Table 4: Objective 2 determining learning across days data 26

Figure 6: Objective 2 determining learning across days data 27

Table 5: Objective 2 determining learning within day data 28

Figure 7: Objective 2 determining learning within day data 29

Table 6: Objective 3 data 30

Figure 8: Objective 3 data 31

References…………………………………………………..……………………………………………32

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