Pes Planus Plantaris (Flat Foot) Decreases Postural Stability of

Basketball Student-athletes through Ground Reaction Force Vector

(vGRF)

Def Primal

1,* a

, Sasanty Kusumaningtyas

and Ermita I. Ibrahim

Universitas Perintis Indonesia, Department of Anatomy and Physiology, Padang, Indonesia

Universitas Indonesia, Department of Anatomy, Jakarta, Indonesia

Universitas Indonesia, Department of Physiology, Jakarta, Indonesia

Keywords Pes Planus Plantaris, Flatfoot, Ground Reaction Force, Static and Dynamic Stability.

Abstract: Purpose: The main objective of this study is to determine the pes planus plantaris condition can contribute

to the disturbance of postural stability on basketball athlete's in static and dynamics activities.

Methods: This cross-sectional quantitative analytical retrospective study on 47 subjects of basketball

student-athletes were identified the foot arch index by footprint extensive area, and AMTI Force flat-form

(force plate) were determined their postural stability. Subjects were conducted in three activities (static,

dynamic vertical jump, and dynamic loading response) for GRF resultant force vectors towards the vertical

plane of body mass (W).

Results: Analytical result obtained 80.9% of subjects had pes planus plantaris. It shows no significant

differences in pes planus plantaris incidence in both sexes subject (p>0.005), however, there are differences

in athlete’s exercise period aspect. Athlete students who have practiced strictly more than 4 years

experienced over 50% for pes planus plantaris, furthermore, long period exercise were believed stimulating

pes planus. The average value of GRF forces vectors of pes planus plantaris subjects on three different

basketball movements shows a significant correlation to postural stability.

Conclusions: Pes planus plantaris affected almost basketball athlete regarding the length and intensity of

exercise performed. The condition significantly contribute to postural stability disturbance on a static

condition, dynamic vertical jump, and dynamic vertical jump loading response.

https://orcid.org/0000-0002-3553-6804

1 INTRODUCTION

Pes planus and pes cavus are leg disorder or lower

extremities abnormalities caused by several factors

such as standing in a long period, bone disorders and

neurological trauma, non-ergonomic shoes, weakness

in ligamentum plantaris, and plantar pedis disorders

related to constituent problems of foot imbalance

(Aydog S. T., et al., 2004; Chuckpaiwong, et al.,

2008; Handrigan, et al., 2012; Sung, P. S., et al.,

2017). Pes planus plantaris (flatfoot) condition

resulting from the occurrence of depression in arcus

longitudinalis medialis (medial longitudinal arch) can

be risk factors of injury in foot overload locomotors

(overuse), and the disruption of tissue trauma in

plantar pedis from persistent weight-bearing

continuously (Boerum V., et al. 2003;

Sung, Paul S.,

2016). Pes planus plantaris is a common occurrence

that often occurs in the sports community, and the

incidence percentage up to 78%. A person with pes

planus plantaris increases forces and energy

consumption while mobilization and higher plantar

pressure during activity (McCormack, et al., 2001;

Sung, Paul S., 2016). Foot arch as contact structure

during body weight-bearing and mobilization can be

suppressed while excessive weight-bearing activities

which lead to lower extremities injury, metatarsals

stress fractures, cuboid syndrome, iliotibial band

syndrome, ligamentum calcaneo-navicularis tear, as

well as plantar pedis compiler structure stresses. It

also related to pathological condition, i.e, diabetes

mellitus that can decrease the quality of tendons

regenerations (Aydog, S T., 2005; Borton, et al.,

Primal, D., Kusumaningtyas, S. and Ibrahim, E.

Pes Planus Plantaris (Flat Foot) Decreases Postural Stability of Basketball Student-athletes through Ground Reaction Force Vector (vGRF).

DOI: 10.5220/0011573500003321

In Proceedings of the 10th International Conference on Sport Sciences Research and Technology Support (icSPORTS 2022), pages 143-151

ISBN: 978-989-758-610-1; ISSN: 2184-3201

143

1997; Chuckpaiwong, et al., 2008; Colo’, G., et al.,

2021; Mazerolle and Stephanie M., 2007; Ahriyasna,

R., et al., 2021).

Basketball as a weight-bearing sport have high

intermittent intensity movement involving jumping

and landing continuously, acceleration, deceleration,

turning, dribbling, shooting, jump shot, jump fake,

pull-ups jumpers, pivoting and some interspersed with

low slow movement intensity (Bressel E., et al., 2007;

Kong, et al., 2015). Jump shot, pull-up jump and jump

fake in basketball are such jumping movement with

strong foot pushing vertically in both parallel feet on

the side of the body. Vertical jump loading response

(slam dunk and set shoot) is carried out with running

and suddenly jumping (weight-bearing loading

response) which provides bigger bodyweight pressure

in forefoot and midfoot (Kong, et al., 2015; McKeag

and Douglas, 2003; Richie and Douglas H., 2007).

The main issue on basketball athlete plantar pedis is

the presence of malformations and injuries due to

overuse (excessive usage) on the important intrinsic

factors in the foot, such as bone, muscle, tendon, and

ligament (Chuckpaiwong, et al., 2008; Clifford,

Amanda Marie, and Heather Holder-Powell, 2010).

Plantar foot pressure and muscles loading forces

during static, walking, and running performances are

influenced by foot arch type, especially to flatfoot

condition (Koshino, Y., et al., 2020; Sung, P. S., et al.,

2017). Biomechanics processes in basketball athletes

activities involve running and jumping with fairly

high level, high to low intensity, repeated sudden

continuous movement on the foot’s muscles and

ligaments (Aydog S. T., et al., 2004). Running and

jumping during basketball game directly affect the

postural stability especially in jumping to landing

initiation on body fulcrum. The decline of arch

curvature is greater in athletes because of body weight

load for 3-6 times, especially in jumping activity

(Wikstrom, Erik A., et al., 2008). Control of balance

is an essential component of human mobility. In some

studies, the structure of the foot arch contributes

greatly to postural stability in controlling balance.

Melzer et. al concluded that higher ground reaction

force (GRF) would decrease postural stability (Aydog

S. T., et al., 2004; McCormack, Anne P, et al., 2001).

These occur because the energy transfer from heel to

toe is not through the medial bearing on the forefoot,

which relates to rapid high pressure on hallux, and the

and 3

metatarsal (Han, et al., 2011). To analyzing

the instability while jumping, the GRF vector is a

perfect predictor (Mazerolle, Stephanie M., 2007).

The results of this study aim to reduce the resultant

amount of GRF to obtain a stable, stronger, and

smoother movement. GRF vector analysis was

conducted if sexes and longer exercise periods

affected the incidence of pes planus. These vectors

will also predict the athlete’s postural stability with

varied arch index.

2 METHODS

This study was a cross-sectional quantitative

analytical at the Department of Anatomy, Faculty of

Medicine, Universitas Indonesia. The force plate was

explored as stability analysis in Somatokinetic

Laboratory in Sports Science Faculty, Universitas

Negeri Jakarta (UNJ). We conducted this research

from November 2016 to April 2017. Samples are

subjects whom basketball student-athletes in the

Faculty of Sport Sciences UNJ for 47 consisting of 29

females in the female's basketball club and 18 males

in the male's basketball club. They had been acceded

written informed consent and approved from the

health research ethical committee of Medical Faculty

of Universitas Indonesia. Foremost, subjects were

screened based on the physical examination criteria,

i.e.; training period at least 6 months with exercise

frequencies 2 times/week minimally, normal BMI, no

abnormalities in the musculoskeletal system of a

lower limb, no pain or disorder experienced in the

trunk and extremities, no diagnosed neurological

disorders, and without under medical treatment.

• Examination of pes planus’ Footprint

Angle ruler (θ goniometer), stamp ink, and footprint

diagram paper were served tools to measure athletes’

arch index on subjects’ plantar pedis (fore-foot,

mid-foot, hind-foot) related to arch index

formulation by Canavagn and McCrory

(1997).

Figure 1: Overview of footprint distribution to calculate

subjects arch index (AI) (McCrory, et al., 1997).

We created our footprint stamp pad to maintain the

clearance and cleanliness of footprint images

generated. Student-athletes would be stepped on

those footprint pads to get colored plantar pedis.

Further, footprint images were created on footprint

diagram paper which we could calculated spacious

printed area to be separated subjects arch index then.

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• AMTI (Advanced Mechanical Technology Inc.)

Accupower Force Flatform Posturography

(Force Plate)

This computerized based tool generates the body’s

forces direction vector to determine the amount of

GRF vector angle θ against the vertical plane of W

with a goniometer device. The examination was

executed on basketball student-athletes postures

without interrupting their regular exercise schedule

and match preparation to avoid injury and fatigue.

Examination of static (single-leg standing on

dominant leg with contralateral leg flexed

approximately 90 degrees) and dynamics postural

stability (vertical jump and vertical Jump loading

response) was performed for 2 minutes each task

(Borton, David C., et al., 1997). The subjects were

instructed to generate three activities on task

performance with their eyes open. We calculated

student-athletes GRF vectors while they were

foothold on AMTI force plate devices by single-leg

standing (on dominant feet), vertical jump, and

vertical jump loading response conditions. We

analyzed forces resultants using a standardized

formula from angles created between vectors streak

and W direction (Figure 3).

• Forces Analysis in Securing Postural Stability

Status

Analysis of subject’s distribution with pes planus

and normal arch measured by univariate chi-square

statistic. The incidence of foot curvature in both

sexes and exercise length period had been calculated

during a similar analysis. We analyzed the effect of

pes planus and normal arch in different gender and

duration of exercise towards postural stability

examined using independent t-test. Statistic analysis

directly carried on the effect of each activity of

static, dynamic vertical jump, and dynamic vertical

jump loading responses. The GRF vector according

to body weight (W) formulated in (Headon, Robert,

and Rupert Curwen, 2001; Hong, et al., 2016):

𝑮𝑹𝑭𝒗 =

𝒎 . 𝒈

𝐜𝐨𝐬 𝜽

The result of forces resultant for GRF vector

accumulated in: 𝑭



⃗



−𝑾



+𝑮𝑹𝑭

Higher force resultant formed on GRF compared to

the bodyweight force, postural stability will decrease

(Headon, Robert, and Rupert Curwen, 2001; Hong,

et al., 2016). To sum up, we applied the resultant

forces of GRF generated to specify our subject's

postural stability.

3 RESULTS

3.1 Characteristics of Research

Subjects

Basketball student-athletes (n=47) were active

student-athletes in the age of 19.38±1.51 deviation

standard. Initial anamnesis involved 18 male

students for 19.17±1.38 and 29 female students for

19.48±1.6. Participating subjects have a normal BMI

for 21.32±1.4. Student’s exercise program runs for 6

days/week, for 120-180 minutes with a 15-30 minute

break period. It performed during 18-22 weeks (±5

months) in each semester. We performed the

incidence of different foot arch related to genders. It

shows a higher percentage of pes planus incidence 4

times than normal arch students. However, it

revealed no significant differentiation in pes planus

distribution on both sexes of the subject with p-

value=0.449 (table 1).

3.2 Footprint Results

Figure 2: Pes planus (A) and normal arch (B) of basketball

student-athletes in UNJ.

Table 1: Foot arch distribution of basketball student-

athletes for both sexes.

Variables

Foot arch

P-value

Pes planus Normal

Men 16 (88.9%) 2 (11.1%)

0.449

Women 22 (75.9%) 7 (24.1%)

Frequencies 38 (80.9%) 9 (19.1%)

When we have seen the proportion of pes planus

subjects, it was found that longer practice performed

will lead to an increased incidence of pes planus. It

was then proven by statistical correlation analysis

with a significant value of 0.008 (table 2).

Pes Planus Plantaris (Flat Foot) Decreases Postural Stability of Basketball Student-athletes through Ground Reaction Force Vector (vGRF)

145

Table 2: Basketball student-athletes foot arch index related to exercise length period.

Variables

Index of the foot arch

Total

Pes planus Normal arch

Duration of

exercise (years)

0-4 amount 2 3 5

% Exercise len

th 40.0% 60.0% 100.0%

5-8 amount 30 3 33

% Exercise len

th 90.9% 9.1% 100.0%

9-12 amount 3 3 6

% Exercise len

th 50.0% 50.0% 100.0%

13-16 amount 3 0 3

% Exercise length 100.0% .0% 100.0%

Value D

.Si

(

ided

)

Pearson Chi-Square 11,945

3 .008

ikelihood Ratio 10.753 3 .013

3.3 Postural Stability on Pes Planus

Plantaris and Normal Arch

Figure 3: GRF force vector illustration in subjects with normal foot arch (A, B, C) and on pes planus plantaris (D, E, F).

3.4 Correlations of Pes Planus and

Normal Arch to Static Postural

Stability

Table 3: Distribution of static postural stability on pes

planus and normal arch basketball student-athletes.

AI N Mean

Std.

Deviation

P-

value

GRF on

static

Pes planus 38 1.6 632 1.8 4397 .043

Normal 9 0.3667 0 .32016

It results in a correlation between the resultant force

on GRF magnitude towards subjects postural

stability in both two types of foot arch with a

significant value of 0.043 (table 3).

3.5 Correlations of Pes Planus and

Normal Arch for the Vertical

Motion (Vertical Jump & Vertical

Jump Loading Response/ Shooting

Position) to Dynamic Postural

Stability

Based on the table 4, statistical results with p>0.05

of GRF resultant force magnitude correlated to the

foot arch type. It indicates that there is a correlation

between the subject postural stability with pes

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Table 4: Distribution of dynamic postural stability with vertical jump and vertical jump loading response on pes planus and

normal arch basketball student-athletes.

ean Std. Deviation

-value

GRF on dynamic vertical

jump

Pes planus 38 15. 2632 8. 82773 .017

Normal 9 7. 8778 2. 23874

GRF vector dynamic loading

vertical jump response

Pes planus 38 30. 9605 15. 21940 .017

Normal 9 17. 9889 6. 50009

planus conditions while performing dynamic

vertical jump activity. A GRF resultant force vector

in vertical jump loading response activity shows the

greater average value on the subject with pes planus

than normal arch subjects. Statistical analysis on

both pes planus and normal foot arch showed

significant association to subject postural stability

with 0.017.

4 DISCUSSION

4.1 Subject’ Characteristics

The subjects had experienced varied pain in the

plantar pedis such as pain in the ankle, heel, knee, or

spine years ago. We believed those findings are

consistent with McKeag's (2003) study which states

that the highest incidence of lower extremity injuries

in basketball athletes, onwards followed by

vertebrae, costae, and upper extremity injuries. The

higher injuries incidence was recorded as strains,

sprains, and lacerations in foot tissues. Our data

disclosed college-level athletes have a higher level

of injury in lower extremities rather than high school

athletes, or basketball athletes as recreational

purposes (McKeag, Douglas, 2003). Distribution of

subjects with normal body mass index (BMI) aims

to avoid any disturbance of stability due to obesity.

As McGraw et al. (2000) study revealed that

postural instability in subjects with obesity indicated

by the displacement vector of energy consumption

compared to subjects without obesity, we keep off

concluding abnormal BMI in our research samples

to reach significant findings.

Commonly known, postural stability is also

affected by the coordination of the brain in the

somatosensory system (visual, vestibular,

proprioceptive) and motoric (musculoskeletal, joint,

soft tissue). In our study, we obtained physical

examination to avoid the influence of both system

works towards postural stability. Physical

examination included personal identity, body

weight, height, health problems diagnosis history in

lower extremities, and training period.

Musculoskeletal system and sensory-motor

inspection cover abnormalities are being felt,

symmetrical differentiation on both extremities,

swelling, pain, gait pattern, muscle tone and

strength, motion agility, and lower extremities

reflexes. Those examinations revealed our involved

research subjects.

4.2 Basketball Student-athletes

Footprint

In our investigation, we examined the basketball

student-athletes arch index by calculating their

spacious footprint area on footprint paper

(millimeter block). These measurements correspond

to the arch index threshold from Cavanagh et al

(1997), which is a more accurate predictor of indices

types of the foot arch, and it has significant rates

closer to the digital scanner footprint (Razeghi,

Mohsen, and Mark Edward Batt, 2002). Arch index

results obtained footprint of 80.9% subject had pes

planus, while the rest of it has a normal arch,

meanwhile, athletes with high foot arches (pes

cavus) are naught. A quote from Borton (1997) and

Anzai et al. (2014) findings, the incidence of pes

planus in athletes has been widely reported and

causing multifactorial problems (bone disorders,

musculoskeletal, and constituent structures

disorders, heavy physical activity, obesity,

developmental settled pes planus).

Pes planus (fallen arch), or also called flatfoot,

planovalgus, or calcaneo-valgus, is a human

underlying of decreasing in the medial longitudinal

arch of the foot and arch deformity due to changes in

the forefoot, mid-foot, and hind-foot area, both

Pes Planus Plantaris (Flat Foot) Decreases Postural Stability of Basketball Student-athletes through Ground Reaction Force Vector (vGRF)

147

starting with symptoms or asymptomatic (Boerum

V., et al., 2003; McCormack, Anne P., et al., 2001;

Sung, Paul S., 2016). The common pes planus

incident factor on sportsmen generally starts from

decrease or loss of function in musculus tibialis

posterior as well as injury (tear) in its tendon,

frequently on arch support tissues, both on the

plantar fascia and ligament composer (Borton, et al.

1997; Yuji Ohta and Emi Anzai, 2014). With the

highest pes planus incident in UNJ basketball

student-athletes, we believe that professional

basketball student-athletes do not realize that they

have an abnormal arch height throughout their

exercise period. Pes planus is still regarded as a

form of change in basketball athletes which no

students effort and intervention in maintaining or

rehabilitating their normal arch. Based on our

investigations on pes planus incidence, we

discovered student-athletes were been wearing flat

soles shoes during exercise and do not even care and

realize serious problems (generally pain sensation)

on their plantar pedis. They assumed that can be

tolerated and will recover soon because it still within

the tolerance limits that would not interfere along

with exercise activities.

4.3 Frequency and Exercise Duration

of Basketball on Pes Planus

Plantaris

In Van Boerum et al (2003) research, foot

dysfunction will deliver the decreasing function of

legs normal structural support. The imbalance in

forces along with activities and movements, heavy

intensity and repetitive activities, weight gain, and

plantar compiler structure weakness, would

potentially decrease the level of foot arch curvature,

and eventually be flattering the arcus longitudinal

medialis (Boerum V., et al., 2003). From a

basketball student-athletes long period exercise that

we revealed, we discovered an increasing incidence

of pes planus. Analysis indicates the arch index in

four (4) years of practice, pes planus incidence will

elevate periodically. Increasing incidence of pes

planus on basketball student-athletes related to the

length of steps while they are doing intensive

exercise. In contrast to the results of Aydog (2004)

findings, it is a negative correlation between the

incidence of pes planus in adolescent basketball

player and non-basketball player on 0.497 and 0.890

significancies (Aydog S. T., 2004). However, what

we discover, exercise length period contributed to

the incidence of pes planus. We believe that pes

planus high percentage incident officially influenced

by the exercise intensity and duration taken, indeed

before and during their education in the UNJ

basketball club. Aydog research (2004) analyzed

basketball players on 1-7 years exercise duration

followed by 8 hours/week exercise intensity,

whereas in our research, subjects performed 1-16

years exercise with 12-16 hours/week. With longer

exercise intensity and intensive frequencies every

single week, we believed it would give chances of

delivering direct injuries due to the over-use of

constituent tissues in the foot arch. What we

convinced similar to Volkof and Klingele research in

Aydog (2004) which regular intensive exercise and

increasing prolonged exercise intensity will result in

flatfoot (pes planus) incidence over running

activities during playing basketball.

Another our finding, student-athletes bodyweight

loading during exercise is concentrated in the

plantar pedis forefoot region. The imposition of

body weight (weight-bearing) for a long time is

often found in student-athletes while running and

making leaps during exercise. We believed high-

pressure forces in the forefoot will lead to stronger

and continuous stretch in the plantar fascia and

posterior tibial tendon. Over-use pulling and

stretching conditions will increase the incidence of

tissue injury or rupture in plantar pedis arch-

supporting tissue. The pain had been experienced by

the entire subject (100%) at plantar fascia, and some

pain in the ankle, heel, and knee. In the end, the

injuries cause weakness of the arch structure and

finally decrease the plantar arch curvature.

4.4 Postural Stability of Basketball

Student-athletes

What we investigated, student-athletes postural

stability measured in three common basketball

activities; standing on a single leg, vertical jump

(jump shot, pull-up jumper or fake jump), and

vertical jump loading response (shooting, slam dunk,

or set shoot). It showed the incidence of pes planus

on basketball student-athletes postural stability

determined instability values. Postural stability

prescribed the extent of instability on student-

athletes from various activities. As far as we noticed,

postural stability in basketball athletes with pes

planus never been assessed in certain activities,

where some basketball studies specifically analyzed

postural stability in static conditions. Talking about

ground reaction forces examined, Headon (2001)

had examined the pressure on the floor for observing

vertical components on GRF used in classifying

movement. He provided details for implementing

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movement initiating systems using vertical

components on GRF. Similar to Headon's, we

calculated forces quantity on the subject’s GRF

resultant towards the vertical force component

(Headon, Robert, and Rupert Curwen, 2001). The

magnitude of each force vector created can not be

illustrated by the force plate examination imaging

that appeared. The data for stability examination was

only a vector force line formed on reaction force by

research subjects loading action. GRF vector

contained in fx, fy, and fz quadrants and only

measured force vector angles magnitude to the

vertical plane (fy). So, it can be determined the

amount of GRF force in subject’s loading activities

(Önell, Annica, 2000).

Hong (2016) explained, since force plate is a

GRF measurement, some studies have utilized force

plate as GRF examinations verification on postural

stability. Hong revealed there was a significant

association on the standard deviation of vertical

vector component (vGRF) to postural stability

review during sitting, standing, and position change.

One empirically previously mentioned that people

with younger age have a greater GRF variability

than older ages with a single leg standing

examination (Hong, et al., 2016). For example, when

body bending movement (shifting pivot center

towards their body mass), there will be a decreasing

acceleration which leads to reduce GRF.

Furthermore, when the body does jump motion

(moving CoM away from the fulcrum), it will

require additional acceleration and acting force on

the fulcrum (Headon, Robert, and Rupert Curwen,

2001). With the occurrence of changes in GRF, it

affects the normalization of vertical force which

further affects the body’s stability. When the force

required to normalize the GRF vector is bigger,

postural stability will decrease.

With different tracking areas in subjects on both

arch indexes, we believe that flatter arch curvature,

especially in athletes, will reduce postural stability

in every activity conducted, both static and dynamic.

Similar in Bressel et al (2007) findings, basketball

athletes have static and dynamic stability problems

rather than in gymnastics and soccer athletes,

however, their stability is still impaired in overall

athletes than non-athletes subjects. What we

analyzed consistent with Kulthanan's (2004)

research, different footprint parameter for national

and non-national athletes was different from non-

athletes. What we believed, fifth metatarsal and long

flat index space in athletes was greater than non-

athletes subjects. Correspondingly, Bressel et al

(2007) claimed that athletes have no interruption at

postural stability compared to non-athletes.

4.5 Relations Pes Planus Plantaris on

Static Activity in Basketball

Student-athletes

From the examination results of two arch types in

static postural stability, it revealed association value

(p<0.05). It explains that the pes planus subject

experienced decreasing postural stability which

leads to the unstable conditions of GRF resultant

toward the body’s vertical plane. Postural stability

by calculating GRF forces on static condition have a

similar tendency with Onell (2000) research. Onell

revealed although the magnitude of vertical force

could be compared, the vertical force component

simultaneously similar to normal and healthy

subjects after stroke (CVA - cerebral vascular

accident). In Sung (2017) study, flatfoot group had

no significant correlation in decreasing of kinetic

stability without visual input, however, it correlated

to visual input performed. On the other hand, Colo’

study in 2020 agreed to what we revealed that

postural stability decreased significantly in the

flatfoot group even the muscles activation onset

during the transition task of double-to single leg

stance did not differ significantly (Koshino, Y., et

al., 2020; Sung, P. S., et al., 2017). Ultimately, there

was the presence of a slight difference between the

GRF to W in subjects in both arch indexes. Finally,

flatfoot condition certainly will affect the subject’s

postural stability. Because a greater amount of force

is required to normalize the W vector, postural

stability decrease directly.

4.6 Relations of Pes Planus Plantaris on

the Dynamic Activity on a Vertical

Jump and Vertical Jump Loading

Response in Basketball

Student-athletes

Assessment of postural stability observed in both

dynamic motions revealed similar results as static

measurement. It showed decreasing postural stability

on student-athletes with pes planus compared to the

normal arch foot. Sato (2006) studied has noted that

dynamic motion analysis in running biomechanics

with force plate can determine the direction and

magnitude of vGRF. This study indicates that the

occurrence of postural instability is caused by the

subject’s injury experienced in the lower extremities.

Sato says that it will lead to abnormal conditions of

Pes Planus Plantaris (Flat Foot) Decreases Postural Stability of Basketball Student-athletes through Ground Reaction Force Vector (vGRF)

149

an anatomical structure in the lower limb plantar

structure, namely pes planus. Anatomical

abnormalities in plantar pedis structure due to force

and pressure that deliver while initial contactor upon

push-off phase (part of a movement vertical jump) in

the dynamic activity will produce vertical GRF force

2 to 3 times towards body weight (Handrigan, et al.,

2012; Sung, Paul S., 2016). Besides, Karlson (2000)

in Hong's (2016) study revealed that the vertical

component correlates to the GRF vector (vGRF)

deviation standard by using the Berg Balance Scale

(BBS) screening tool. It provided an equal value of

GRF similar to the force plate examination revealed.

What we found, force flat-form posturography (force

plate) generated to calculate the association of GRF

vector force resultant (vGRF) against basketball

student postural stability in static and dynamic

conditions.

From what we discovered, the pes planus

plantaris incident correlated to the subject's postural

stability significantly. On dynamic vertical jump

motion, GRF resultant towards vertical plane

generated 15.26 N, causing a decreasing trend of the

subject’s postural stability. The mean force resultant

towards vertical plane force in pes planus plantaris

was two times higher than normal foot arch subjects.

A similar analysis of pes planus plantaris athletes

also detected higher postural instability during

dynamic vertical jump loading response movement.

It was proven based on GRF force average resultant

to vertical plane forces (W) that vertical jump

loading response had a higher instability value rather

than vertical jump movement. This theory had a

similar finding to Primal (2018) that athlete’s

postural stability were significantly decreased and

disturbed through their postural sway area with the

range of center of pressure (CoP) (Primal, et al.,

2018).

In this final discussion, we conclude that weight-

bearing activities while exercising can increase the

incidence of pes planus plantaris. It relates to

Toullec's (2015) study which declared the

pathophysiological occurrence of pes planus

plantaris on weight-bearing condition. It would

continuously disrupt and reduce some supporting

structures function in a longitudinal medial arch,

especially in the posterior tibial tendon and plantar

fascia. As well as in Aydog's (2005) research, pes

planus plantaris on both lower extremities

commonly occur in handball player athletes (such as

basketball) with high-level weight-bearing activities.

Formation of pes planus plantaris will ultimately

affect postural stability in basketball student-athletes

(Aydog, S T., 2005; Toullec, E., 2015). We would

like to emphasize the importance of maintaining

plantar arch shape normalities. Pes planus plantaris

conditions will reduce postural stability which then

affects a person's performance in varied activities,

especially in athletes which required good

performance and excellences during practices and

games. We believe this conclusion is related to

Bressel et al (2007) and Sung (2015) studies that

subjects with flatfoot have greater GRF force

threshold than normal arch subjects. The disruption

of body stability will affect the athlete’s

performance. As we noticed, there is very little

previous research that analyzes the effect of pes

planus plantaris on athlete's postural stability,

specifically in sports with weight-bearing activities.

5 CONCLUSION

Concluded for about four-fifths of basketball

student-athletes in UNJ experienced pes planus

plantaris, it proved without significant association

on both sexes, however, the length of exercise

period they performed giving significant correlation.

Pes planus plantaris associated with decreasing of

postural stability range on athletes static, dynamic

vertical motion (vertical jump), and dynamic

shooting position (vertical jump loading response)

conditions.

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Pes Planus Plantaris (Flat Foot) Decreases Postural Stability of Basketball Student-athletes through Ground Reaction Force Vector (vGRF)

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