The Effects of Various Customised Mouthguard Designs on

Physiological Parameters and Comfort in Male Boxers

Raya Karaganeva

, David Tomlinson

, Susan Pinner

, Adrian Burden

Rebecca Taylor

and Keith Winwood

School of Healthcare Science, Manchester Metropolitan University, All Saints Campus, Manchester, U.K.

Department of Exercise and Sports Science, Manchester Metropolitan University, Cheshire Campus, Crewe, U.K.

Keywords: Custom-made Mouthguard, Boxing, Exercise Performance, Respiratory, Oxygen Uptake, Ventilation, Heart

Rate, Blood Lactate.

Abstract: Athletes, who use mouthguards (MGs) as a protective device, often experience obstruction of airflow and

interferences with performance. The aim of this study was to investigate the influence of three custom–made

MGs (MG1, MG2, MG3), which differed in design and thickness, on respiratory flow and blood lactate during

exercise. Fourteen elite male boxers (Age: 26 ± 8 yr; Mass: 80±11) performed newly developed sport specific

protocol under laboratory conditions on four occasions – without a MG and with each of the three MGs. The

exercise consisted of 4 boxing rounds of 3 mins, with a minute rest after each round. Breath-by-breath analysis

(METALYZER® 3B, Cortex) showed that there were no differences in the uptake of oxygen (p > 0.157)

between the four conditions. Likewise, the use of different MG did not affect blood lactate accumulation (p =

1.00). However, at the end of the first round the minute ventilation was higher when MG3 was used (86.2 ±

17.5 L/min) compared to MG2 (71.7 ± 13.2) and having no MG (73.7 ± 16.4) (p = 0.002). The fact that a

negative effect was not determined on physiological responses could further encourage players to use MGs

during both training and competition.

1 INTRODUCTION

A survey showed that 35.9% amateur boxers have

sustained tooth injuries (N=338, males, 17.6 yrs);

with crown fractures being the most common (40.7%)

(Emerich and Gazda, 2013). Using a mouthguard

(MG) in boxing is compulsory and has meant the

athletes are 1.6-1.9 times more likely to prevent such

injuries (Knapik et al., 2007). Customised MGs were

found to be superior to the other ‘over–the–counter’

types in regards to functionality, fit and comfort

(Duarte–Pereira et al., 2008; El–Ashker and El–

Ashker, 2015). However, there are no set guidelines

proposing the ideal characteristics of custom devices,

therefore numerous variations of design exist.

There is an underlying belief amongst some sport

participants that wearing a MG causes considerable

discomfort, which could often reduce its use and

player compliance (Gebauer et al., 2011). This could

be due to the large popularity of commercial devices

that usually have poor fit and low retention.

Additionally, questionnaire–based studies have

reported interferences with breathing as another

reason for the low usage of MGs (Boffano et al.,

2012; Kececi et al., 2005). However, previous

research has shown no significant effects on gas

exchange parameters and heart rate (HR) when a MG

was worn compared to no MG condition (p > 0.05)

(Bourdin et al., 2006; Duarte–Pereira et al., 2008; El–

Ashker and El–Ashker, 2015; Kececi et al., 2005).

El–Ashker and El–Ashker (2015) compared the

effects of a stock MG and customised MG, whereas

Duarte–Pereira et al. (2008) investigated the

influence of a ‘boil–and–bite’ and customised MG.

Both studies identified that the custom–made devices

should be the preferred option due to minimal

interference with performance.

To support the current findings, future work

should use sport specific test protocols to investigate

cardio–pulmonary changes in athletes wearing

various MGs (El–Ashker and El–Ashker, 2015;

Kececi et al., 2005). Additionally, further research

could help determine whether the reported issues

regarding obstruction of breathing are valid or based

on psychological perception (Morales et al., 2015;

Kececi et al., 2005).

Karaganeva, R., Tomlinson, D., Pinner, S., Burden, A., Taylor, R. and Winwood, K.

The Effects of Various Customised Mouthguard Designs on Physiological Parameters and Comfort in Male Boxers.

In Extended Abstracts (icSPORTS 2018), pages 14-18

2 OBJECTIVES

The present study investigated the influence of three

various custom–made MGs on respiratory flow and

accumulation of blood lactate during newly

developed sport specific protocol. It is hypothesised

that there will be no difference in these physiological

parameters when exercise is performed with and

without a MG.

3 METHODS

Prior to any experimental work ethical approval was

obtained from the School of Healthcare Science,

Manchester Metropolitan University (Ethics Number:

SE151683).

Fourteen elite male boxers, training at the same

boxing academy, were recruited and completed all

sessions. The physical characteristics of the sampled

population are shown in Table 1. The average

participation in sport was 7±9.38 years, whereas the

time of competing was 5±7.85 years. All athletes

were physically fit, currently taking no medications

that may influence airflow, muscle fatigue and HR.

Medical and dental assessment was completed to

ensure all athletes met the inclusion criteria.

Table 1: Description of the sampled population (N=14).

Variable Mean SD

Age (yr) 26 ± 8

Mass (kg)

± 11

Height (cm)

178

± 5

Body Mass Index

± 4

Hb (g/dL)

15.1 ± 0.9

Lung Function (%)

± 7

2max

(ml/kg/min) 54 ± 7

Blood samples were taken to determine the levels of

haemoglobin (Hb). If any signs of anaemia (Hb < 13

g/dl) were present, the individuals were excluded

(HemoCue® 201+ System, Crawley, England).

3.1 Fabrication of Mouthguards

Figure 1. illustrates the selected MG designs, which

were chosen based on common practice and

previously published literature (Morales et al., 2015;

Takeda et al., 2014). Once informed consent was

obtained, a dental clinician took alginate dental

impressions (Tropicalgin, Zhermack SpA, Italy).

Then, three MG devices were fabricated for each

participant in the dental laboratories at Manchester

Metropolitan University. All MGs were

thermoformed on a Biostar machine (BIOSTAR®,

SCHEU-DENTAL GmbH, Iserlohn, Germany) and

made of clear ethylene vinyl acetate (EVA) blanks,

120 mm Ø (diameter) (Bracon Ltd, Heathfield, UK).

MG1 was fabricated from a 4 mm single EVA blank

with a 4 mm extension in the palate, which was not

present in the other two designs. In comparison, MG2

and MG3 were made of two layers, 2 mm and 4 mm

EVA blanks. MG2 consisted of a double layer at the

posterior region only, whereas MG3 had a double

layer covering the anterior and the posterior teeth.

Figure 1: Customised mouthguards used by all participants.

3.2 Exercise Protocol

All participants were asked to attend six laboratory

sessions in total, with at least a week in-between. The

first and the last session involved running on a

treadmill (Woodway Pro XL, Waukesha, US) until

exhaustion (VO

2max

test) to identify any change in the

level of aerobic fitness pre and post testing with MGs.

The participants ran at the same speed, which was

pre-selected individually during the warm-up stage

(10 ± 0.65 km/h), and a 1% increase in incline every

minute, starting at 0%. The remaining four sessions

included a 10-min warm-up and a sport specific

protocol where all participants used the same punch

bag (50cm Ø x 140cm, 60kg) (PRO–BOX Colossus

Punch Bag, JPLennard Ltd., UK) and a pair of boxing

gloves (10oz) (Lonsdale, Shirebrook, UK). The sport

specific protocol consisted of 4 boxing rounds of 3

mins, with a minute rest after each round. During

Figure 2: Breath–by–breath data collected through a

facemask during exercise.

The Effects of Various Customised Mouthguard Designs on Physiological Parameters and Comfort in Male Boxers

each 3-min round, participants were given a verbal

signal ‘Go’ every 6 secs and they all performed the

same combination of 4 straight maximum punches.

The participants were randomly assigned to perform

with either one of the chosen MGs or without a MG.

3.3 Physiological Parameters

The following rest measurements were recorded at all

visits: mass, stature, blood pressure, HR, Hb and

blood lactate (BLa). During each testing session, the

athletes wore a facemask, which was connected to a

breath-by-breath analyser (METALYZER® 3B,

CORTEX, Leipzig, Germany) (Figure 2.). The main

parameters assessed in this study were absolute

oxygen uptake (VO

), minute ventilation (VE), HR

and BLa. A baseline reading of the above

measurements was taken by asking the participants to

remain at rest for one minute prior to exercise. After

each round a BLa sample was taken (Biosen C-line

Analyser, Cardiff, UK) and participants were asked to

rate their level of exertion on a standard Borg scale (6

– No Exertion to 20 – Maximal Exertion).

To control any possible variability in the data, the

participants were asked to follow the same dietary

intake and physical activity 24h prior to a session.

Temperature and humidity were consistent during all

visits, 20.0°±0.6 and 50% ±4 respectively.

3.4 Statistical Analysis

Statistical analyses were performed using IBM SPSS

Statistics, Version 24.0. Armonk (IBM Corp., New

York, US) and Microsoft Excel (2013).All cardio-

pulmonary measurements were analysed using

rolling averages of the last 30 secs and the maximum

values of each interval (round). Paired samples t-test

was used to compare the results of the VO

2max

sessions. Depending on the parametricity of the data,

repeated measures ANOVA (within subjects) with

post-hoc (Bonferroni) or Wilcoxon test were

performed to identify the effect of MGs on the

aforementioned physiological parameters. Statistical

significance was set at p ≤ 0.05.

4 RESULTS

The first maximal effort exercise showed a lower

2max

(50±7 < 54±7 ml/kg/min, p = 0.032) and

max

(195±12 < 197±11 bpm, p = 0.527) than the

second test at the end of the study.

All participants performed the sport specific

protocol with each of the three MGs and without a

MG. There were no statistical differences in the

average VO

(L/min) in the final 30 seconds of each

round between all MG conditions (p = 0.623) (Table

2.). However, the VE (L/min) at the minute prior to

exercise (pre-test) and at the end of the first round was

significantly higher when the participants wore MG3

compared to no MG and MG2 (p < 0.018). It was also

found that at the end of the protocol HR was higher

when MG3 was used compared to MG1 (p < 0.041).

The highest levels of BLa was recorded for MG1 and

the lowest BLa occurred when no MG was used,

although these were not statistically different (p =

1.000) (Figure 3.). The rate of perceived exertion,

which varied between ‘Somewhat hard’ and ‘Hard’ at

the end of the exercise, did not differ significantly (p

= 0.221).

Figure 3: The differences in blood lactate levels at rest, post warm-up, rounds 1-4 (R1, R2, R3, R4) and 5 min post-exercise

between conditions - with and without a MG (N=14). The error bars represent the standard deviation.

0,00

1,00

2,00

3,00

4,00

5,00

6,00

Resting Post warm-

R1 R2 R3 R4 5 min post-

exercise

Blood Lactate (mmol/L-1)

Intervals

No MG MG1 MG2 MG3

icSPORTS 2018 - 6th International Congress on Sport Sciences Research and Technology Support

Table 2: The Mean ± SD of oxygen uptake (VO

) and minute ventilation (VE), and the maximum values of heart rate (HR)

for each round (R1-R4) while wearing no mouthguard (No MG) or any of the three selected designs (MG1, MG2 or MG3).

The mean of VO

and VE represents the rolling average of the last 30 secs of the boxing rounds (N=14).

Variable No MG

MG1

MG2

MG3

Group

Differences

(L/min)

Pre-test/ Rest

0.63 ± 0.12

2.60 ± 0.40

2.60 ± 0.50

2.57 ± 0.47

2.62 ± 0.45

0.63 ± 0.13

2.65 ± 0.42

2.71 ± 0.40

2.72 ± 0.37

2.67 ± 0.41

0.60 ± 0.14

2.61 ± 0.47

2.75 ± 0.37

2.64 ± 0.45

2.69 ± 0.36

0.59 ± 0.17

2.69 ± 0.42

2.72 ± 0.51

2.64 ± 0.51

2.68 ± 0.56

0.157

1.000

0.623

0.901

1.000

VE (L/min)

Pre-test/ Rest

23.2 ± 3.9

73.7 ± 16.4

79.3 ± 20.8

79.5 ± 20.2

83.3 ± 21.5

22.7 ± 5.0

73.4 ± 15.7

78.9 ± 15.9

81.3 ± 18.2

83.3 ± 18.1

19.7 ± 3.9

71.7 ± 13.2

78.9 ± 14.1

79.2 ± 15.3

82.1 ± 14.7

20.5 ± 6.2

86.2 ± 17.5

81.3 ± 23.5

79.7 ± 22.3

82.9 ± 24.1

(a-c), (a-d)

(a-d),(c-d)

0.018

0.002

1.000

HR (bpm)

Pre-test/ Rest

105 ± 20

156 ± 24

159 ± 18

157 ± 22

160 ± 16

103 ± 16

162 ± 25

165 ± 17

165 ± 22

165 ± 16

108 ± 33

165 ± 24

171 ± 18

168 ± 23

167 ± 17

102 ± 17

165 ± 22

171 ± 16

171 ± 20

169 ± 16

(b-d)

0.701

0.096

1.000

0.074

0.041

Significant main effects are highlighted in bold. Group differences (p <0.05) are highlighted by: ns = no significance,

= No MG and MG1;

= No MG and MG2;

No MG and MG3;

MG1 and MG3.

1. Data are Mean ± Standard Deviation. Significant main effects are highlighted in bold.

2. Group differences between No MG and MG1 are highlighted by a = P<0.05, aa = P<0.01, aaa = P<0.001.

4. Group differences between No MG and MG2 are highlighted by b = P<0.05, bb = P<0.01, bbb = P<0.001.

5. Group differences between No MG and MG3 are highlighted by c = P<0.05, cc = P<0.01, ccc = P<0.001.

5 DISCUSSION

To the best of our knowledge, the current study is the

first one to investigate the influence of three various

customised MGs on respiratory flow and BLa of elite

boxers, performing a sport specific protocol.

The sampled population showed good level of

aerobic fitness (VO

2max

= 52±7 ml/kg/min, HR =

193±7 bpm). In order to minimise the training effect

between the testing sessions, it was important to

recruit participants with high fitness level and same

standard of competition.

No statistical differences were observed in VO

(L/min) and BLa with and without a MG, or between

MG type. Participants also reported similar levels of

perceived exhaustion during all tests. Although, at the

first round VE was highest when MG3 was worn

(86.2±17.5) and lowest at MG2 condition

(71.7±13.2), these differences could possibly be

explained by the differences in VE prior to exercise

(p < 0.018). Hence, it could be considered that the

changes in VE did not occur due to change of MG

condition but due to variation of warm-up intensity.

At the last boxing round, HR values were

significantly lower during MG1 condition compared

to having MG3 (p < 0.041). From these findings, it

could be concluded that there were no interferences

with respiratory flow when customised devices were

used during exercise. Additionally, this was

supported by the similar BLa values between

conditions.

There are controversial views about the effects of

MGs on performance and physiological biomarkers

(Bourdin et al., 2006; Duarte–Pereira et al., 2008; El-

Ashker and El-Ashker, 2015; Gebauer et al., 2011;

Kececi et al., 2005; Morales et al., 2015; Schulze et

al., 2018). Previously, only one study has examined

the effects of stock and custom-made devices on the

airflow of male boxers (El-Ashker and El-Ashker,

2015). However, their exercise protocol consisted of

The Effects of Various Customised Mouthguard Designs on Physiological Parameters and Comfort in Male Boxers

running on a treadmill at two different intensities (12

and 14 km/h). Statistical differences were only

recorded at the higher intensity exercise, where the

whilst wearing a stock MG was 40.54±5.68

(ml/kg/min) compared to 46.48±3.65 (ml/kg/min)

with custom-made MG and 47.37±5.34 (ml/kg/min)

without a MG (p = 0.02) (El–Ashker and El–Ashker,

2015). Although, this test may have high

physiological value, the exercise protocol did not

specifically address the characteristics of boxing. It

could be argued that the newly developed protocol of

the current study could provide more objective results

to determine the effect of customised MGs on airflow

and blood lactate accumulation. Future work should

examine changes in physiological parameters in

professional boxing, where the number of rounds and

exercise effort are higher.

The outcomes of the present study may have

important implications in relation to increasing the

use of custom-made MGs. Coaches should be aware

of the benefits of custom devices and educate not only

the athletes but also the parents of young children.

The fact that a negative effect was not determined on

physiological responses could further encourage

players to use MGs during both training and

competition.

ACKNOWLEDGEMENTS

The authors would like to thank all participants, Prof.

Julian Yates (University of Manchester, UK) for

taking all dental impressions and Kerry Jacobs, Garry

Pheasy and Steven Morton for their technical support

(Manchester Metropolitan University, UK).

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icSPORTS 2018 - 6th International Congress on Sport Sciences Research and Technology Support