Adherence to an Injury Preventative Warm

Up Program Elicits Performance

Enhancements in Male Collegiate Footballers

Following a 5 Week Warm Up Intervention

Student Name:

Jordan Tyrer

Programme of Study:

BSc Sport and Exercise Science

Supervisor:

Dr. Neil Messenger

CENTRE FOR SPORT & EXERCISE SCIENCES

Faculty of Biological Sciences

UNIVERSITY OF LEEDS

Abstract

The International Federation of Football Associations’ (FIFA) injury preventative warm up

program, the “FIFA 11+” can elicit physical performance improvements in footballers.

However, factors such as the time-consuming nature of such programs mean they are often

unused in sub-elite football. The purpose of this study was to establish whether an adapted

and shorter version of the “FIFA 11+” could still elicit performance improvements in adult

footballers. 5 week warm up programs were administered to 14 male collegiate footballers

(age; 20.57 ± 1.40 yrs, height; 179.58 ± 5.92 cm, weight; 76.97 ± 8.22 kg) with participants

performing either an injury preventative warm up program (n = 7), or a dynamic warm up

program (n = 7) as a control. Paired-sample t-tests (P < .05) showed significant

improvements in jump height for the countermovement jump (CMJ) (p = .033) and

countermovement jump with arms (CMJWA) (p = .037), as well as a non-significant

improvement (p = .077) in single leg stance score for the injury preventative group. The

dynamic warm up group observed no significant improvements in any performance test.

These results suggest that a shorter version of the “FIFA 11+” can still elicit performance

enhancements in male adult footballers.

Keywords: warm up, performance enhancement, countermovement jump, balance,

injury prevention

Introduction

Like with most sports, playing football carries a risk of injury at both amateur and

professional level1. Historically, dynamic stretching as part of a warm up strategy prior to

sport participation has been strongly advocated and widely used2. Typically, a dynamic warm

up would contain active stretches and exercises that mimic the movements associated with

the sport in question in order to raise body and muscles temperature

3. However, there is

evidence to suggest that the use of these warm up protocols alone do little to reduce the risk

of serious lower limb injuries4-7

, such as anterior cruciate ligament injuries. More recently,

specific injury prevention programs have been designed and developed in order to target and

reduce the injury risks associated with football. Because football is such a widely played,

spectated and well financed sport, footballs governing body, the International Federation of

Football Associations (FIFA) have investigated ways in which best to reduce the associated

injury risks of football. With help from the FIFA Medical and Research Centre, a series of

injury preventative warm up programs were designed with the aim of significantly reducing

the injury risks associated with football world-wide8. Initially “The 11” protocol was

proposed, which was then later updated to the “FIFA 11+” program. The “FIFA 11+”

contains exercises that are considered to be pivotal in reducing the injury risk in football. It

focusses on core stabilisation, eccentric training of thigh muscles, proprioceptive training,

dynamic stabilisation and plyometric exercises. The main focus of the program is the

promotion of proper neuromuscular control during all of the exercises in order to fully

facilitate the physical and neural adaptations that the warm up program is designed to elicit9.

Following the introduction of specific injury preventative programs such as the “FIFA 11+”,

there is a growing amount of evidence that shows the warm up protocol can significantly

reduce the risk of injury8,10-13

, thus showing how important an effective injury preventative

warm up program can be in reducing the risk of injury to footballers.

Because of their impact on reducing injury, professional football clubs will often

spend up to 45 minutes completing warm up programs14

. In an elite environment where the

coaching staff have a near continuous interaction with the players throughout a week, as well

as access to specific support staff such as physiotherapists, sports scientists and strength and

conditioning coaches, these lengthy warm up procedures are easily achievable. When we also

consider the huge financial practices of elite football, it is perhaps understandable as to why

such a length of time is dedicated to preventing injury in squads that can potentially be worth

millions of pounds.

In non-elite settings however, meta-analysis have found that injury preventative warm

ups are rarely, if at all adhered to by coaching staff13

. Often, a short dynamic warm up

procedure is used by coaches as a means of warming up their players as opposed to a more

specific injury preventative program, perhaps due to a lack of knowledge regarding the

benefits of an injury preventative warm up13

. As well as this, in sub-elite and amateur football

where coaching staff may only work with their players for a few hours a week, coaches will

rarely afford long durations of time to performing a warm up. In practice the “FIFA 11+”

takes 20-25 minutes to perform entirely15,16

which in reality, coaches may consider too long a

duration to afford to a warm-up process within their limited interaction time. As a result,

injury preventative warm up programs may be neglected, thus potentially exposing players to

a higher risk of injury.

It has been suggested that in order to improve the uptake of injury preventative warm

ups by coaches, it may be important to focus on player performance improvements as a

secondary effect of a specific injury preventative warm up17

. A number of studies have

investigated the effects that injury preventative warm ups have on jumping and balancing

performances, both of which are important attributes in footballers18

. Investigations into the

performance benefits associated with injury preventative warm ups is a relatively recent area

of research where the results are not entirely conclusive. The majority of studies show how

significant performance improvements are observed following injury preventative warm up

interventions16,18-21

whilst other studies have demonstrated contrasting results 22,23

.

It could be said that if a warm up program could reduce the risk of injury, elicit

significant performance improvements and last for a shorter duration of time than previous

injury preventative warm ups such as the “FIFA 11+”, then perhaps coaches may be more

receptive to the use of injury preventative programs.

As a result, the purposes of this study are to investigate whether such a program can

elicit significant balance and jumping improvements in male collegiate footballers. A 5 week

intervention period of an injury preventative warm up, adapted from the “FIFA 11+” but that

takes less time to complete, was administered to collegiate footballers from the University of

Leeds Men’s Football Club. It was hypothesised that the injury preventative warm

intervention would elicit significant performance improvements in the jumping and balancing

ability of the participants who received the warm up program. It is also hypothesised that a

control group who were administered a traditional dynamic warm up program will observe no

significant improvements in physical performance tests.

Methods

Participants for the study were volunteers from the University of Leeds Men’s

Football Club. The study included 14 injury free club members (age; 20.57 ± 1.40 yrs, height;

179.58 ± 5.92 cm, weight; 76.97 ± 8.22 kg). Ethical approval was obtained from the

university’s ethical committee for the protection of the participants throughout the testing and

training procedures. All participants were provided with information regarding the

procedures and consequences of participating in the study before the study began. The

participants subsequently gave informed consent and completed health screening

questionnaires prior to participation in the study.

For both the benchmark and final testing days, all participants were provided with the

same model of cushioned running shoe (Saucony ProGrid 12) in their corresponding size.

The participants then completed a warm up containing a combination of injury preventative

and dynamic exercises (table 1) before testing procedures began, in order to minimise the risk

of injury14

during the balance and jump tests.

Table 1: Contents and procedures of the warm up administered to all participants prior to the

benchmark and final testing protocols.

Order Exercise Repetitions Exercise Description

1 Squat 6

Participants should perform a squat

movement to the best of their ability,

keeping their heels on the floor and a

neutral head position.

2 Calf raise 10

Participants should extend at the ankle

joint, whilst standing unaided, keeping

balance and performing the movement as

competently as possible.

3 Single leg ½

squat 4 each leg

Keeping their hands on their hips, and the

non-supporting leg in front of the body,

participants are to perform 4 single leg ½

squats until their flexed knee is at a 90⁰

angle before returning to a standing

position and repeating the process.

4 Double leg hop 6

Whilst standing with feet shoulder width

apart, participants should perform 6 quick

consecutive jumps.

5 Single leg hop

and holds 3 each leg

Participants are to hop on one leg 3 times

before attempting to cushion the landing in

a stationary position before returning to a

standing position and repeating the process.

Once the warm up was completed the participants performed the single leg stance test in

accordance with the test’s defined protocol24

. Each participant performed four balance tests in

total starting with a leg of their choice, followed by the opposite leg. After a 30 second rest

between each trial the participants then repeated the procedure, and their performance was

timed via a stop-watch. The timer was started when the participant moved onto one leg with

his hands on his hips and was stopped when the participant lost balance or re-adjusted his

posture, as defined by the testing protocol24

.

Following the balance tests, the participants completed jumping trials consisting of

3counter-movement jumps (CMJ) followed by 3 counter-movement jumps with arms

(CMJWA). The CMJ protocol required participants to keep their hands on their hips

throughout the jump as a means of assessing isolated leg power, where-as the CMJWA

protocol required participants to jump with their hands and arms unrestricted, thus allowing

for the use of their upper extremities in assisting the jump. As such, it was expected that the

participants would achieve greater jump heights in the CMJWA test as opposed to the CMJ,

as it is more of a test of a person’s whole body power rather than just leg power alone, as

seen with the CMJ. Both tests were used as opposed to just one so that a more extensive

measure of the performance effects of the different warm up protocols could be examined.

All jumps were performed from two adjacent force platforms, in conjunction with a 13

camera Qualisys OQUS system to record three dimensional kinematic data, which was used

to evaluate whether the landing of each jump had occurred upon the force plate. As such, a

single retro-reflective marker was attached using double sided adhesive tape to the same part

of the heel on each of the right shoes that were given to the participants. Prior to the

completion of the jumps each participant performed a 3 second static trial in order to obtain

each participant’s weight. This required each participant to stand still upon the force platform

thus giving each participant’s stationary ground reaction force. This value could then be

divided by acceleration due to gravity (-9.81 m∙s) thus giving the weight of each participant.

The participants were then assigned to either the injury preventative warm up group

or the dynamic warm up control group. The injury preventative group were members of the

University’s 1st and 2

nd team squads whilst the members of the control group consisted of the

University’s 3rd

and 4th

team squads. Both groups trained separately and on different days to

one another, there for the delivery and monitoring of both warm up protocols could be

accounted for. Both groups were evenly represented by each playing position (goalkeeper; n

= 1, defender; n = 3, midfielder; n = 2, attacker; n = 1).

Benchmark testing occurred at the beginning of the playing season, with both warm

up interventions taking place immediately afterwards, as the playing season got underway.

Final testing occurred midway through the playing season. Both groups were administered a

5 week warm up intervention that they completed 3 times a week, prior to their training

sessions and matches. The injury preventative warm up included a 4 minute pre-warm up

activation period that consisted of exercises aimed to increase the number of recruited motor-

units as well as the rate of which those motor-units were recruited within the major muscle

groups associated with football25

(table 2), followed by a 10-12 minute injury preventative

warm up consisting of 16 exercises (table 3). In comparison the control group were

administered a 10-12 minute football specific dynamic warm up (table 4). Both warm up

procedures required the same equipment (8 cones) and were performed using the same layout

(figure 1).

Figure 1: Layout of both the injury preventative and dynamic warm up areas.

● = cone

15 m

30 cm

ST

AR

T

FIN

ISH

Table 2: Contents and procedures of the pre-injury preventative warm up activation exercises

prescribed to the injury preventative group.

Order Exercise Repetitions/Duration Exercise Description

1 Squat 8

Participants should perform a squat

movement to the best of their ability,

keeping their heels on the floor and a

neutral head position.

2 Squat into

calf raise 6

Participants should perform a squat

movement however when returning to

standing position participants are to fully

extend ankles, knees and hips and arrive

into a calf raise position, holding it for three

seconds before repeating the whole process.

3

Single-leg

static balance

with eyes

closed

30 seconds each leg

Participants are to close their eyes and

attempt to balance in a stationary position

on one leg for 30 seconds before swapping

legs

4 Single leg ½

squats 4 each leg

Keeping their hands on their hips, and the

non-supporting leg in front of the body,

participants are to perform 4 single leg ½

squats until their flexed knee is at a 90⁰

angle before returning to a standing

position and repeating the process.

5

Single leg

hop and

holds

4 each leg

Participants are to hop on one leg 3 times

before attempting to cushion the landing in

a stationary position before returning to a

standing position and repeating the process.

6

Single leg

partner

balance

30 seconds each leg

In partners, participants are to face one

another and hold their partners forearms

whilst attempting to balance on one leg

while their partner applies light,

unpredictable pressure in different

directions.

Table 3: Contents and procedures of the injury preventative warm up administered to the

injury preventative group.

Order Exercise Exercise Description

1 Jogging For 3 lengths of the warm up area, participants should jog at

comfortable pace.

2 Skipping For 2 lengths of the warm up area, participants should skip as high as

they can whilst maintain forward momentum.

3 Dynamic lunges

with torso twist

For 1 length of the warm up area, participants should perform

consecutive lunges for either leg, twisting their torso across their front

knee and alternating legs each time.

4 Dynamic sumo

squats

For 1 lengths of the warm up area, participants should adopt an extra

wide squat stance and perform a squat with the same movement

principles as a standard squat.

5

Bent leg kick

across with torso

twist

For 1 length of the warm up area, participants should kick across the

midline of their body, whilst rotating their torso in the opposite

direction to the kick. Alternating legs each time.

6 Straight leg kicks

For 1 length of the warm up area, participants should kick as high as

they can with a straight leg in a controlled manner, alternating legs

each time.

7 Door kick downs

For 1 length of the warm up area, participants should perform a

controlled kicking motion that mimics the movement of attempting to

kick through a door.

8 Tic-Tocs

For 1 length of the warm up area, participants should swinging each

leg laterally and as high as possible, keeping both legs straight whilst

maintaining forward momentum and alternating legs each time.

9 Bounds For 1 length of the warm up area, participants should run with a

purposely over-extended stride length at a quick pace.

10 Single leg bounds

For 2 lengths of the warm up area, participants should perform a single

leg jumping action. Participants should then repeat the process for the

opposite leg.

11

Broad jump into

60% of a maximal

sprint

For 1 length of the warm up area, participants should perform a single

maximal broad jump, followed by a sprint of 60% of their maximal

speed.

12 Broad jumps For 1 length of the warm up area, participants should perform

consecutive maximal broad jumps for the length of the warm up area.

13

Run into maximal

vertical jump and

land

For 2 lengths of the warm up area, participants should perform a

maximal vertical jump following a short run up, land and jog through

to the end of the warm up area. Participants should then repeat the

process jumping off of the opposite leg.

14

Footwork patterns

into 75% of

maximal sprint

For 3 lengths of the warm up area, participants should perform a

precise ‘in and out’ whole body movement through the starting cones

before performing a 75% of their maximal sprint speed though to the

end of the warm up area.

15 Sprint variations

For 5 lengths of the warm up area, participants should complete 5

sprints of incrementally increasing speed that includes a sudden stop at

the end of the warm up area.

Table 4: Contents and procedures of the football specific dynamic warm up administered to

the dynamic warm up group.

Order Exercise Exercise Description

1 Jogging For 3 lengths of the warm up area, participants should jog at a

comfortable pace.

2 Skipping For 2 lengths of the warm up area, participants should skip as high

as they can whilst maintain forward momentum.

3 Sidesteps

For 2 lengths of the warm up area, participants should face

perpendicularly to the direction of warm up area whilst quickly

performing a quick lateral sidestep movement for the length of the

warm up area. Participants should then repeat the process facing in

the other direction.

4 Lunges For 2 length of the warm up area, participants should perform

quick lunges for either leg.

5 Straight leg

kicks

For 2 lengths of the warm up area, participants should kick as high

as they can with a straight leg, alternating legs each time.

6 Hamstring

sweeps

For 2 lengths of the warm up area, participants should best

perform a ‘hamstring sweep’ by keeping one leg bent with the

other straight and out in front of them. Whilst keeping their heel

on the floor and raising their toes, a stretch through the calf and

hamstring should be felt, participants should simultaneously bend

at the hips bringing their torso towards the ground and sweep the

floor with their hands in one smooth motion. Participants should

then repeat the process for the opposite leg whilst maintaining

forward momentum.

7 Open/Close

the gate

For 2 lengths of the warm up area, whilst balancing on one leg

participants should flex their non-supportive leg at the hip bringing

their knee towards their torso, then laterally move the leg away

from the midline of their body in a smooth and controlled

movement, alternating legs each time. For the second length

participants should repeat the process but in the opposite order so

that the leg starts laterally and moves back toward the midline of

the body.

8 Sprints

For 5 lengths of the warm up area, participants should perform 5

sprints of incrementally increasing speed that includes a sudden

stop at the end of the warm up area.

Upon completion of the 5 week period, all participants were recalled to perform the

same testing procedures as before, with all tests being completed in the same order.

Following the conclusion of the warm up intervention and final testing procedures,

Visual3D software was used in order to obtain flight time for each of the participant’s jumps,

measured from the instant of take-off to the instant of landing (figure 2). Using the flight time

of each jump, jump height was calculated using the same process as shown by previous

studies26,27

that also calculated jump height from force platform data. This method of

determining jump height shows high levels of reliability and validity28

and is shown below:

𝐽𝑢𝑚𝑝 𝐻𝑒𝑖𝑔ℎ𝑡 = 𝑣𝑡𝑜

2

2∙𝑔 Eq 1

where vto is the vertical take-off velocity, and g is acceleration due to gravity (-9.81 m∙s-1

).

In order to calculate vto, flight time for each participant’s jumps was used in the following

equation:

𝑣𝑡𝑜 = 𝑔∙𝑡𝑓𝑙𝑖𝑔ℎ𝑡

2 Eq 2

where t flight is flight time, and g is acceleration due to gravity (-9.81 m∙s-1

).

0

500

1000

1500

2000

2500

0 0.625 1.25 1.875 2.5 3.125 3.75 4.375 5 5.625

Gro

un

d r

ea

ctio

n f

orc

e (N

)

Time (s)

t flight

Figure 2: method of obtaining flight time (tflight) from a participant’s CMJ

performance.

Once jump heights had been calculated for each participant’s CMJ and CMJWA trials

paired-samples t-tests were performed using SPSS Statistics in order to determine significant

changes between pre and post intervention scores for both groups in all of the balance and

jump trials, with a significance value of P < .05 indicating a significant change.

Results

Significant changes (P < .05) were found in performance scores following both the

injury preventative and dynamic warm up protocols (table 5).

Table 5: Descriptive statistics of the performance measure outcomes following paired-

samples t-test analysis (P < .05)

Performance

measure Warm-up

Group mean

change (post

intervention

– pre

intervention)

Standard

deviation

t-

value

p-

value

CMJ Dynamic .20 cm ± 3.81 cm .140 .893

CMJ Injury

preventative 2.85 cm* ± 2.73 cm 2.77 .033*

CMJWA Dynamic - 2.10 cm* ± 1.77 cm 3.74 .020*

CMJWA Injury

preventative 3.10 cm* ± 3.06 cm 2.69 .037*

Single leg

stance test Dynamic - 2.19 s ± 9.60 s .604 .568

Single leg

stance test

Injury

preventative 13.37 s ± 16.60 s 2.13 .077

*significant difference between pre and post intervention score

A significant improvement (t [6] = 2.77, p = .033) in CMJ height was found for the

intervention group, with all members of the group observing an improvement in jump height

following the 5 week intervention (figure 3). In comparison, the control group observed a

non-significant improvement (t [6] = .140, p = .893) for CMJ height (figure 4), following the

5 week dynamic warm up protocol.

Figure 3: Pre and post CMJ heights for the injury preventative group

Figure 4: Pre and post CMJ heights for the dynamic warm up group

A significant improvement in jump height for the CMJWA (t [6] = 2.69, p = .037)

was also found for the intervention group, with 6 of the group’s participants showing an

improved jump height (figure 5) following the injury preventative warm up. The control

group in comparison actually observed a significant reduction (t [6] = 3.74, p = .020) in jump

0

5

10

15

20

25

30

35

40

45

1 2 3 4 5 6 7

Ju

mp

Hei

gh

t (c

m)

Participant

Pre-intervention Post-intervention

0

5

10

15

20

25

30

35

40

1 2 3 4 5 6 7

Ju

mp

Hei

gh

t (c

m)

Participant

Pre-intervention Post-intervention

height for the CMJWA (figure 6) following the dynamic warm up protocol. As expected,

individual CMJWA scores for both groups were greater than their corresponding CMJ scores.

Figure 5: Pre and post CMJWA heights for the injury preventative group

Figure 6: Pre and post CMJWA heights for the dynamic warm up group

A non-significant improvement of (t[6] = 2.13, p = .077) was found for the

intervention group’s balance scores, with every member of the group observing an

improvement (Figure 7) following the injury preventative warm up intervention. In

0

5

10

15

20

25

30

35

40

45

50

1 2 3 4 5 6 7

Ju

mp

Hei

gh

t (c

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Participant

Pre-intervention Post-intervention

0

5

10

15

20

25

30

35

40

45

1 2 3 4 5 6 7

Ju

mp

Hei

gh

t (c

m)

Participant

Pre-intervention Post-intervention

comparison, the control group saw a non-significant reduction (t [6] = .604, p = .568) in

balance score, with just 2 members of the group showing an improved score (Figure 8)

following the 5 week dynamic warm up program.

Figure 7: Pre and post balance scores for the injury preventative group

Figure 8: Pre and post balance scores for the dynamic warm up group

0

10

20

30

40

50

60

70

80

90

100

110

120

1 2 3 4 5 6 7

Tim

e in

ba

lan

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s)

Participant

Pre-intervention Post-intervention

0

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1 2 3 4 5 6 7

Tim

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Pre-intervention Post-intervention

Discussion

The purpose of this study was to test whether a shorter version of the “FIFA 11+”

warm up protocol could elicit jump and balance score improvements in 14 male collegiate

footballers. A 5 week injury preventative warm up program elicited significant improvements

in both CMJ (p = .033) and CMJWA (p = .037) scores, where-as a dynamic warm up

prompted no significant change in CMJ (p = .893) score and actually saw a significant

reduction in CMJWA (p = .020) performance. The injury preventative group also saw an

improvement in balance score, however the improvements were found not to be significant (p

= .077), whilst the control group also saw no significant change in balance scores (p = .568).

When trying to understand the mechanisms that may have caused the improvements

in jump heights for the intervention group, it should be considered that any improvements in

leg power would likely be associated with an improved ability to jump18

. The explosive

single and double leg bounding and jumping exercises that were included in the injury

preventative warm up are likely contributors to the improvements in jump height scores as

such exercises improve the strength, neuromuscular recruitment and co-ordination of the

muscle groups associated with jumping29

. When we also consider that the injury preventative

group performed these exercises 3 times a week for a total of 5 weeks we can perhaps begin

to understand why improvements in jump performance were observed. In comparison the

control group did not perform these type of exercise and subsequently saw no improvements

in CMJ and actually saw a significant reduction in CMJWA score.

The reasons for the reduction in CMJWA scores for the dynamic group are less

obvious. As part of the dynamic warm up, the group didn’t perform the same exercises

associated with improved jumping performance as seen in injury preventative group. This

could explain why no jumping improvements were observed, although as to why each of the

participants CMJWA scores significantly reduced is more puzzling. Perhaps the timing of the

intervention may have played a part. Seeing as how the benchmark testing occurred before

the playing season was fully underway and the final testing occurred midway through the

season accumulated fatigue from the participant’s matches and training session may have

meant fatigue, which can significantly affect vertical jump performance30

, caused a reduction

in final testing jump performances. If we also consider that lower extremity fatigue can cause

biomechanical alterations during jumping and landing and increase the risk of injury31

, as

well as cause participants to produce significantly reduced amounts of force when jumping

and landing whilst fatigued32

we can perhaps understand why reduced jump scores were seen

for the control group. One reason as to why the injury preventative group did not display the

signs of fatigue could be down to the constituents of the warm up program potentially

protecting the participants against the effects of accumulated fatigue. The injury preventative

group were consistently performing exercises that have been shown to reduce the risk of

injury8,10-13

, the mechanisms of which could be due to those exercises eliciting strength and

neuromuscular control improvements29

in the lower extremities. Neuromuscular control is

defined as the unconscious response to a change in joint stability33

, which has been shown to

improve significantly following injury preventative warm ups15,16,20,21

. As a result, these

changes may have allowed for a greater tolerance towards fatigue, thus potentially explaining

why the injury preventative group’s results seemed less affected than the control groups.

Several limitations to the study should be noted. It could be said that the group

assignment of the participants is one such limitation. The intervention group’s participants

were 1st and 2

nd team squad players only, whilst the control group were made up of 3

rd and 4

th

team players. This was done due to the training schedules of all of the playing squads and so

that both warm up interventions could be delivered to both the control and injury preventative

groups. However, seeing as higher level footballers often display greater physiological

capabilities34

such as strength and power levels35

, aerobic endurance36

and fatigue tolerance34

to name but a few, it would make sense that higher level squad players would produce greater

results in physical performance tests like jump and balance tests. The results of this study

would advocate this theory, however due to the nature of the paired sample t-test, it is the

degree of change from pre to post scores for each group, independently from one another that

is measured for. This would suggests that the main variable responsible for the significant

improvements in testing scores was the type of warm up intervention and the difference in

physical capabilities of each group’s participants was less of a factor.

The study’s small sample size could also be considered a limitation to this study.

Small sample sizes can affect the reliability of a study’s results37

and may also stand as a

possible explanation as to why despite a relatively large post intervention improvement in the

injury preventative groups averaged balance scores the changes were found not to be

significant. When considering the balance performances of both of the groups, we can see

that the results of both groups performances contain large standard deviations from the mean

score (table 5). Because of the large within-subject differences and a small sample size, the

ability to determine whether changes in balance score were predominantly due to the type of

warm up becomes difficult. As a result, it could be said that a larger sample size may have

allowed for results that more reliably reflect the effects of different warm up interventions on

balancing ability.

Interestingly, similar research that examined the performance effects of the full “FIFA

11+” protocol20

included a much larger sample size (intervention; n = 42, control; n = 39). It

was shown that the injury preventative program did lead to significant improvements in

balance performances (p = .005) in time-to-stabilisation test. This potentially highlights the

effects that a larger sample size has on balance scores, although it should be noted that the

full “FIFA 11+” protocol was used as well as a longer intervention period and so direct

comparisons between the studies are difficult.

The single leg stance test was used as the balance test for this study. It was chosen as

it requires no additional equipment and the test’s simplicity allowed for a relatively efficient

means of testing, which was necessary as all 14 participants were tested on the same days in

the same laboratory. However, the test relies on a subjective assessment of when the

participant has lost balance and although the testing protocol defines when a loss of balance

occurs24

it is still reliant on human judgement which in turn can be erroneous and lack

consistency. On top of this, football is a highly dynamic sport, so the use of the single leg

stance test may not truly represent the balance requirements of the sport. Previous

research15,20,21

has demonstrated significant improvements in balance performance following

similar warm up interventions when a more dynamic means of balance assessment such as

the time-to-stabilisation test20,21

or the star excursion balance test15,16

was used. This could

perhaps explain why no significant improvements in balance performance were observed

following the injury preventative warm up intervention as the testing protocol may not have

best represented the participants’ balancing capabilities.

When looking at jump performances specifically, CMJ performance significantly

improved in collegiate footballers following a warm up intervention containing similar

exercises to those used in the injury preventative warm up in this sudy19

. As well as this,

following an intervention of FIFA’s “The 11” program, the predecessor to the “FIFA 11+”,

significant improvements in CMJ performance were observed18

, albeit in young children (age

10.4 ± 1.4 yrs). On top of this, similar studies to this one have shown that both balance ability

and jump performance were significantly improved following warm up interventions21

,

further adding to the evidence that injury preventative warm ups can elicit performance

improvements in footballers. Having said this, contrasting studies have shown no significant

improvements in performance tests following injury preventative warm ups17,20,22,23

. As a

result, the performance impacts of an injury preventative warm up in footballers remains

inconclusive.

In conclusion, this study has shown that jump performances are significantly

improved following an injury preventative neuromuscular warm up intervention, where- as a

dynamic warm up intervention does not elicit such improvements as was hypothesised.

Although balancing ability was shown to be improved following the injury preventative

intervention it was found to be in a non-significant manner, contrasting to previous research.

The results of this study would suggest that a shorter and adapted version of the “FIFA 11+”

program is enough to elicit jump performance improvements in collegiate footballers. Injury

preventative warm ups significantly reduce the risk of injury in adult footballers8,10-13

however there is a growing amount of evidence, this study included, that would suggest

injury preventative warm ups can also elicit significant performance improvements as well.

This perhaps shows the importance of injury preventative warm ups for not only the well-

being but also the performance of athletes.

Acknowledgements

The author is highly thankful to the University of Leeds Men’s Football Club for the

use of their players as the participants for this study as well as the University of Leeds Sports

Science Department for the use of its facilities.

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