Rahul Ragunathan

11-17-14

Bioe404

Abstract

TBD

Introduction

TBD

Methods

TBD

Results

The force of the quadriceps force was on average higher for walking compared for that of

running. The maximum quadriceps force was also found to be higher over the course of motion of

walking compared to the maximum quadriceps force over the course of running. The figures below

depict the quadriceps force over the course of a forward stride for both walking and running.

The above 2 figures show Fq as a function of time for both running and walking. As shown, the

maximum Fq value for walking is significantly larger when compared to Fq for running. The exact values

for max Fq for both walking and running are shown below.

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45

-250

-200

-150

-100

-50

0

50

Fq vs Time(walking)

Fq vs time

Time(seconds)

Fq (N

ewto

ns)

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35

-120

-100

-80

-60

-40

-20

0

20

Fq vs Time (running)

Series2

Time(seconds)

Fq (N

ewto

ns)

Figure 1: The graphs above depict Fq vs time for running and walking. The graph is primarily negative except for a single point where Fq becomes positive. This is likely due to the foot slowing down nearing the end of extension. Note that the total time is not the same for both walking and running as the stride for running takes a shorter amount of time.

Theta was also measured as a function of time in order to confirm that the motion tracking software was

effectively capturing the data. The results of this study can be found below.

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45

-2

-1.5

-1

-0.5

0

0.5

Angle vs Time

Running, ThetaRunning, BetaWalking, ThetaWalking, Beta

Time(s)

Angl

e (R

adia

ns)

Table 1: The table below summarizes essential information for walking and running as described above. Note that the quadriceps force for walking is twice as high compared to the quadriceps force for running. The average walking force is also greater compared to that of running.

Walking Running

Max Fq Max Fq

-224.39 -111.69

Average Fq Average Fq

-74.10 -65.71

Discussion

Based on the data collected, several key conclusions regarding the model used for

walking and running can be drawn. Although the conclusions may seem counterintuitive, several key

observances were made between walking and running was observed.

The angles of theta and beta were observed to be larger for running compared to

walking for the majority of the motion as the strides for running are slightly longer and therefore involve

greater levels of extension. This motion as observed by the conducted simulation is fairly intuitive and

expected and validates the model studied.

Despite the results regarding the angular position being expected, the results for the

Quadriceps Force were unexpected. Despite basic intuition that would result in the maximum

quadriceps force being larger for running than for walking, the data yielded the opposite result. Walking

was shown to have both a larger quadriceps force as well as a larger average quadriceps force.

However, there is a possible reason as for why this unanticipated phenomenon occurred. One

possibility involves the simplification that was made regarding the fact that the normal force exerted by

the ground on the leg at the beginning of motion is 0. This is clearly not the case as running clearly

results in greater impact with the ground on every successive stride and therefore a greater force.

Based on this simplification, it would make sense that the leg accelerates faster from the very first stride

from the ground while running and that a lower quadriceps force would be needed in order to maintain

this higher angular acceleration present.

Figure 2: Theta and beta values vs time for running and walking are shown. Theta is measured from the vertical axis at the knee while Beta is measured from the vertical axis at the hip.

Future experiments may involve studying various different muscles in addition to the

quadriceps force throughout walking and running as well as studying the clockwise swing of the leg

during running. In addition, a model which uses the normal force from the ground as a parameter may

help explain any shortcomings in the proposed model of motion.