Is Staggered Greater Than Parallel Feet Placement?

Kinematic Analysis for the Start of Backstroke-Swim Style

Erma Aniska Fauziah, Aziz Rubiansyah and Agus Rusdiana

Faculty of Sport and Health Eduation, Universitas Pendidikan Indonesia, Dr. Setiabudhi Street No. 229, Bandung

aniskaerma@gmail.com

Keywords: Backstoke, comparison, propulsion.

Abstract: Most athletes have minimal speed in terms of starting compared with their cyclic movement whereas a good

start contributes to the swimming performance. So, the purpose of this research is to know the more

effective and efficient placement of leg position and efficient for the start of backstroke-swim style. The

samples were eight swimmers (average age, weight, and height: 18.9 years old, 62kg, 174cm) from Aquatic

Student Activity Unit at UPI who became participants of this study, using purposive sampling technique.

The swimmers‘ starting movement was recorded with 60Hz camera, and then applied into movement

analysis software: kinovea. The analyzed reaction components were (1) initial angle, (2) angular velocity,

and (3) reaction time between the placement of parallel and staggered leg positions. The results of t-test

analysis showed that there is no difference in the initial angle, angular velocity, and the reaction time

between the placement of parallel and staggered feet placements on the bottom starting of backstroke-swim

style (p> 0.05).

1 INTRODUCTION

Swimming performance in short-range competitions

is measured by the amount of time of the following

four components: start, swim, reversal, and finish

(Blanksby, Nicholson and Elliott, 2002; Theut and

Jensen, 2006). The success of the start is said to be

an important element in the swimming competition.

The start consists of several phases: block, flight,

entry, glide, leg kicking and swimming (Arellano et

al., 2000; Vantorre, Chollet and Seifert, 2014). The

study mentions, from the total length of swimming

time in a pool of 25 yards, the start can contribute

25%. On the 50 yard distance, the start can

contribute 10%, and 5% at 100 yard distance (Kilan

i, Al-Tuieb and Kilani, 2013). Previously, the grab

start method was considered the fastest compared to

other start methods. The results of the temporal

analysis of kinetic and speed measurements show

that grab start produces better vertical impulses and

take off speeds than the track start, while the track

start is faster when leaving the start block

(Benjanuvatra et al., 2004). Currently, many world-

class swimmers use the track start method. Track

start that resembles running start is used because it

has advantages compared to grab start. First,

swimmers can enter the water more quickly because

the center of gravity will run almost straight forward

until it reaches its maximum point to fall into the

water. Second, the swimmer's feet can lead to better

forward resistance when the swimmer has twice the

strength. Because the back feet do the first repulsion

to push the foot forward, there is a movement of

momentum, which is then followed by the forceps of

the front foot (Badruzaman, 2011). At the start of

backstroke-swim style with parallel and imparallel

placement of legs (one below and one above), there

was no difference (p> 0.05) of average speed and

horizontal distance, and no difference in leg

movement during start (Theut and Jensen, 2006).

Parallel feet placement, in which the feet are dipped

into the water when hand-off and take-off positions

are at the body mass center position, and the speed

of the horizontal body mass center, are better than

the placement where the feet are not dipped into the

water. As for the placement of parallel feet position

that are not dipped in water shows better results in

the component of contact time with the wall, and the

center speed of the horizontal and vertical body

mass on the phase flight. There is no difference in

water range (horizontal), back angle and start time of

5 m from both placement of the foot (de Jesus et al.,

Fauziah, E., Rubiansyah, A. and Rusdiana, A.

Is Staggered Greater Than Parallel Feet Placement? - Kinematic Analysis for the Start of Backstroke-Swim Style.

In Proceedings of the 2nd International Conference on Sports Science, Health and Physical Education (ICSSHPE 2017) - Volume 2, pages 14-17

ISBN: 978-989-758-317-9

2013). Placement of feet above the water surface is

also better in terms of speed start (p <0.01) in, and

take-off horizontal (p = 0.01) in comparison with the

placement of feet under the water, but have a smaller

horizontal peak power (p = 0:02) (Nguyen et al.,

2014).

The mechanical principle of movement at the

start of swimming is associated with the action-

reaction principle (Third Newton ‘Laws). If there is

any change of state from static to motion, or from

motion to static, there must be cause or influence.

The influence or cause is the style. At the bottom

start of the backstroke-swim style, there is a force

called propulsive force (Stager and Tanner, 2005).

The force works when the foot does repulsion

against the block starting wall, causing the body to

have back repulsion. When the force occurs, an

angle formed by the shin, knee joint, and thigh bone

is formed. If the resulting angle is smaller and the

body is more inclined forward, in other words the

horizontal distance from the point of the body

should be minimized, or the weight point near to the

side of the pedestal, it will produce an increased

movement speed to a direction. The principle of

action-reaction also explains that to produce a large

reaction, a strong support is needed. A strong

pedestal will produce good power (Grimshaw and

Burden, 2007; McGinnis, 2013).

Using the basis of movement mechanical

principle, the aim of this study is to compare the

repercussions between the parallel and staggered

feet placements, in which their repulsions consist of

the following components: initial angle, angular

velocity, and reaction time. Therefore, the

hypothesis of this research are as follows: (1) Is

there an initial angular difference between parallel

and staggered foot placements? (2) Is there a

difference in angular velocity between parallel and

staggered feet placements? (3) Is there any

difference in reaction time between parallel and

staggered feet placements?

2 METHODS

The samples in this study were eight athletes of

backstroke-swimming style from the Aquatic SAU

at UPI (Average age: 18.9 years old, weight: 62kg,

height: 174cm). Samples were set based on

the characteristics of the swimmer's ability by using

purposive sampling.

The used research method used was experimental

method with one-shot case study design (Fraenkel,

Wallen and Hyun, 2012). The experiment was

conducted three times for each feet position

(staggered and parallel). Both of the feet position

were placed on the surface of the water (Emerson)

with consideration to avoid water resistance and

slippage. All three experiments were recorded using

a digital video camera placed at a distance of 5

meters (Vantorre et al., 2010; Vantorre, Chollet and

Seifer t, 2014; de Jesus et al., 2015) and operated at

a frequency of 60Hz (underwater camera nikon

coolpix aw110) . Next, the video image is processed

by kinovea software to see the swimmer’s

movements during the start of repulsion. Measurable

components using this software are distance, angle,

coordinate point, and speed (Kinovea, 2015).

Figure 1: Parallel (a) and staggered (b) feet placements.

3 RESULTS AND DISCUSSION

Table 1 shows descriptive data from the results of

parallel and staggered foot placement repulsions for

three trials. The average angle formed early in the

first experiment is smaller than experiments 2 and 3

both for positioning of parallel (44.87 º ± 5.92) or

staggered (45.88 º ± 9.57) feet, so is with angular

velocity which shows better numbers in the first

experiment (parallel = 286.36º / s ± 26.83; staggered

= 281.43º / s ± 64.60). This can happen because in

the first experiment the sample had not experienced

fatigue. There is a causal relationship between

muscle fatigue and high intensity exercise. High

intensity exercise with anaerobic metabolism can

lead to decreased contractile function (Westerblad,

Allen and Lännergren, 2002). In this case the athlete

was in maximum capacity to produce power or

power output (Vøllestad, 1997). The average angle

of initial angle and angular velocity (table 1a) of the

two feet’s in each experiment indicates that there is

conformity with the presumption of the mechanical

movement described previously, that if the formed

initial angle is small, it will result in a velocity

a b

Is Staggered Greater Than Parallel Feet Placement? - Kinematic Analysis for the Start of Backstroke-Swim Style

change in a large direction and vice versa

(Grimshaw and Burden, 2007; McGinnis, 2013). As

for the reaction time of each experiment, they only

show difference of 0.01 seconds to 0.02 seconds, in

which the parallel feet placement was 0 .02 seconds

faster than the staggered. However, it does not

indicate that parallel feet placement is better than

staggered because the difference is only slightly (see

at table 1b). The staggered feet placement allows

swimmers to reach water further (because foot in

lower position pushed earlier and is then followed

by the other foot) so it takes a little longer for the

swimmer to do entry phase. It can also be caused by

internal factors of the athletes themselves, for

example the athletes‘ habits in using the feet parallel

position when starting the backstroke-swim style.

Reaction time in the start of swimming is the

reaction time generated when the start sign is

sounded, where a foot repulses the repulsion board

and the head streams the water until the beginning of

the glide/stroke movement is performed. There are

several factors that influence reaction time that are

associated with human performance, including: (1)

the number of stimulus-response alternatives, (2) the

stimulus-response match, (3) the stereotyped

population, and (4) the number of exercises

(Schmidt and Lee, 2014 ). In some cases, stimulus-

response compability and the number of exercises

are the main factors affecting reaction time. With so

much practice, the stimulus-response process gets

closer to the automation reaction. So, the more often

the muscle is trained, the better the reaction will be

generated when faced with a stimulus or stimulation

of movement.

Table 1: Results of starting repulsion on backstroke-swim

style (initial angle, angular speed, reaction time) on each

trial (mean ± sd).

Initial

Angle(°)

Angular

Velocity(°/s)

Reaction

Time(s)

Parallel 1

44.87±5.92

286.36±26.83

0.72±0.92

Parallel 2

52.75±15.17

255.11±41.89

0.71±0.06

Parallel 3

48.12±11.58

276.20±44.16

0.72±0.10

Staggered 1

45.88±9.57

281.43±64.60

0.78±0.14

Staggered 2

46.75±10.96

258.40±61.06

0.76±0.15

Staggered 3

49.12±9.61

245.99±49.76

0.80±0.16

Table 2: Differences in the average of repulsion results

between parallel and staggered feet placements

Variable

Parallel

(mean±sd)

Staggered

(mean±sd)

value

Initial

Angle

(°)

48.58±9.2

47.25±9.2

0.289

0.777

Angular

Velocity

(°/s)

272.56±27

.67

261.94±33

.20

0.695

0.498

Reaction

Time (s)

0.72±0.08

0.78±0.09

-1.504

0.155

From the results of the difference test analysis

(table 1b) between parallel and staggered feet

placements for the initial angle component (p =

0.777), angular velocity (p = 0.498), and reaction

time (p = 0.155), each had p> 0.05. This means that

there is no significant difference in starting angle,

angular velocity, and reaction time between parallel

and staggered feet placements. It is different to what

happens at the start of track start method that is

considered more effective and efficient, because it

allows swimmers to reach the water further at a

horizontal distance, and faster because of the

pedestal area is in a unstable state so that will cause

the forward movement more quickly. However, at

the start of the mechanical back force, the movement

is strongly influenced by the projection point of the

center of gravity. The center of gravity is one of the

important factors determining movement because

the center of gravity can affect one's stability and

balance. At the bottom start, the center of gravity is

just under water and beyond the pedestal field.

Therefore, the swimmer must have a grip as well as

strong hands and muscles to support the body in

order not to fall into the water or slip before take-off

start.

4 CONCLUSIONS

In this study, the parallel and staggered feet

placements have (initial angle, angular velocity, and

time reaction) relatively similar repulsion results.

This means that no feet position has been found to

be more effective and efficient for swimmers when

starting the backstroke style. This study needs to be

updated by looking at other factors that may affect

the swimmer's start results, such as athlete's

experiences, the condition or duration of training,

muscle flexibility, platform conditions, fatigue, and

athlete's nutrition. In addition, the use of more

ICSSHPE 2017 - 2nd International Conference on Sports Science, Health and Physical Education

samples is strongly recommended to be able to

generalize the results of the study.

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Is Staggered Greater Than Parallel Feet Placement? - Kinematic Analysis for the Start of Backstroke-Swim Style