foot abduction in first foot strike

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14 Νοε 2013 (πριν από 3 χρόνια και 9 μήνες)

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The

features

interaction

of

foot

and

ground

mostly

determine

efficiency

of

high

speed

run

(Bates,

1983
;

Lee

&

Piazza,

2009
)
.

But

now

there

aren't

justified

recommendations

about

optimal

of

foot

abduction

in

first

foot

strike

in

sprinting
.

So

the

aim

of

this

study

was

comparison

of

kinematic

characteristics

of

athlete's

center

of

mass

(CM)

in

sprinting

with

forward

and

outward

toes

position
.

Introduction

Methods

Four

male

sprinters

were

tested

for

this

study

(age

19
.
3
±
2
.
0

years,

body

mass

71
.
5
±
8
.
5

kg,

height

182
.
8
±
7
.
2

cm,

100

metres

best

11
,
23
±
0
,
25

s)
.

Every

participants

had

two

attempts

in

50

metres

maximal

speed

running
:

first

attempts

with

comfortable

foot

position

in

first

foot

strike

and

second

attempts

with

toes

forward
.

3
-
D

video

analysis

(Qualisys,

six

cameras

ProReflex

with

the

frame

rate

120

Hz)

was

used

for

evaluating

kinematic

characteristics

of

athlete's

CM
.

The

data

were

filtered

with

the

2
nd

order

of

lowpass

filter

(
10
Hz)
.

Were

analyzed

kinematic

characteristics

of

athlete's

CM

from

takeoff

moment

of

one

leg

to

takeoff

moment

of

other

leg
.

Videotaping

performed

on

38
-
42

metres

of

distance
.

One
-
way

analysis

of

variance

was

used

to

examine

statistical

differences

of

data
.

Kinematics of athlete’s center of mass in sprinting at various
foot abduction in first foot strike

Oleg Nemtsev & Mikhail Shubin

Adyghe State University (Maykop, Russia) & Kuban State University of Physical Education, Sport and Tourism (Krasnodar, Russia
)

Results

Value

of

foot

angle

(Figure

1
)

in

first

attempt

was

significantly

large

than

in

second

attempt

(Table

1
,

p<
0
.
05
)
.

However

no

significant

differences

(Table

1
,

p>
0
.
05
)

of

following

characteristics

between

run

with

both

first

foot

strike

techniques

were

found
:

average

velocity

of

CM,

ground

contact

time,

flight

time,

horizontal

displacement

of

CM

in

direction

of

moving

during

ground

contact

time

and

during

flight

time,

vertical

displacement

of

CM

during

ground

contact

time

and

during

flight

time
.

References

Bates,

BT

(
1983
)
.

Foot

function

in

running
:

researcher

to

coach
.

Proceedings

of

I

International

Symposium

on

Biomechanics

in

Sports
.

San

Diego,

USA,

293
-
303
.

Lee,

SS

&

Piazza,

SJ

(
2009
)
.

Built

for

speed
:

musculoskeletal

structure

and

sprinting

ability
.

J

Exp

Biol,

212
(
22
),

3700
-
3707
.

Table 1

Mean (

S.D.) of running technique's characteristics at
various foot abduction in first foot strike

Data

Comfortable
foot position

Toes forward

p

Foot angle (
°
)

19.9
±
5.9

10.9
±
4.4

p<0.05

Ground contact time (s)

0.098
±
0.008

0.100
±
0.007

p>0.05

Flight time (s)

0.146
±
0.014

0.152
±
0.015

p>0.05

Athlete’s center of mass variables


Velocity (
m/s
)

9.30
±
0.35

9.12
±
0.20

p>0.05

Horizontal displacement
during ground contact
time (m)

0.83
±
0.09

0.84
±
0.08

p>0.05

Horizontal displacement
during flight time (m)

1.27
±
0.11

1.29
±
0.11

p>0.05

Vertical displacement
during ground contact
time (m)

0.02
±
0.00

0.02
±
0.00

p>0.05

Vertical displacement
during flight time (m)

0.04
±
0.01

0.04
±
0.02

p>0.05

Discussion

Results

of

present

study

haven't

shown

what

foot

position

toes

forward

or

outward

in

the

first

foot

strike

in

maximal

speed

run

is

better
.

Horizontal

velocity

of

CM

not

increased

significantly

after

decrease

of

foot

angle
.

At

the

same

time

not

all

participants

of

this

study

really

completed

their

task

to

turn

toes

forward
.

It

is

shown

that

foot

position

in

first

foot

strike

is

strong

skill

and

planting

foot

with

zero

angle

(neutral

position)

can

be

reason

of

larger

changes

of

kinematic

characteristics

of

CM

than

in

present

study
.

Figure 1: The method for determining the foot angle (bottom view).

Foot angle

contact: oleg.nemtsev@mail.ru