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  1. 1. RESEARCH & SCIENCETABLE OF CONTENTS1. The effects of mouthpiece use on gas exchange parameters during steady-state exercise in college-aged men and women The Journal of the American Dental Association2. The effects of mouthpiece use on salivary cortisol levels during exercise The official Journal of the American College of Sports Medicine3. The effects of mouthpiece use during endurance exercise on lactate and cortisol levels The official Journal of the American College of Sports Medicine4. The effect of mouthpiece use on muscular endurance Southeast Chapter of the American College of Sports Medicine5. MP use increases VO2, VCO2 and VO2/kg during steady state running Southeast Chapter of the American College of Sports Medicine6. Effects of mouthpiece use on airways Openings Lactate Levels in Healthy College Males Compendium: A Supplement of Continuing Education in Dentistry7. Effects of Mouth Piece Use on Auditory and Visual Reaction Time in College Males and Females Compendium: A Supplement of Continuing Education in Dentistry8. The Role of Intraoral Protective Appliances in the Reduction of Mild Traumatic Brain Injury Compendium: A Supplement of Continuing Education in Dentistry9. A Study on the Effectiveness of a Self-fit Mandibular Repositioning Appliance on Increasing Human Strength and Endurance Capabilities Knoxville, University of Tennessee10. The Effects of ArmourBite® Mouthpiece Use on Baseball Pitching Velocity. Rod Dedeaux Research & Baseball InstituteOther Research Accepted for PublicationAccepted for publication in renowned medical journals (pending print)1) The effects of mouthpiece use on cortisol levels during an intensive resistive bout of exercise
  2. 2. The effects of mouthpiece use on gas exchange parameters during steady-state exercise in college-aged men and women Dena P. Garner, Wesley D. Dudgeon, Timothy P. Scheett and Erica J. McDivitt J Am Dent Assoc 2011;142;1041-1047 The following resources related to this article are available online at ( this information is current as of September 1, 2011): Updated information and services including high-resolution figures, can be found in the online version of this article at: Downloaded from on September 1, 2011 This article cites 23 articles, 11 of which can be accessed free: Information about obtaining reprints of this article or about permission to reproduce this article in whole or in part can be found at:© 2011 American Dental Association. The sponsor and its products are not endorsed by the ADA.
  3. 3. RESEARCHThe effects of mouthpiece use on gasexchange parameters during steady-stateexercise in college-aged men and womenDena P. Garner, PhD; Wesley D. Dudgeon, PhD; Timothy P. Scheett, PhD; Erica J. McDivitt, MS Downloaded from on September 1, 2011R esearch in the late 1970s and early 1980s indicated that mouthguards may AB STRACT enhance performance during Background. The authors conducted a study to assess thestrength and endurance exercise.1-3 effects of custom-fitted mouthpieces on gas exchange parameters,However, the research findings were including voluntary oxygen consumption (VO2), voluntary oxygendifficult to interpret because of the consumption per kilogram of body weight (VO2 /kg) and voluntarysubjective methodology used. carbon dioxide production (VCO2).Garabee1 reported that endurance Methods. Sixteen physically fit college students aged 18 throughathletes felt they recovered more 21 years performed two 10-minute treadmill runs (6.5 miles perquickly after endurance training hour, 0 percent grade) for each of three treatment conditionsand could run at a higher intensity (mouthpiece, no mouthpiece and nose breathing). The authorswhen wearing a mouthpiece than assigned the conditions randomly for each participant and for eachwhen not wearing a mouthpiece; session. They assessed gas exchange parameters by using a meta-however, he provided no physiolog- bolic measurement system.ical measures from the study. Results. The authors used analysis of variance to compare all Smith2,3 reported the results of variables. They set the significance level at α = .05 and used atwo studies in which football players Tukey post hoc analysis of treatment means to identify differencesincreased their muscular strength between groups. The results showed significant improvementswhen wearing a mouthguard (P < .05) in VO2, VO2 /kg and VCO2 in the mouthpiece condition.adjusted kinesiologically versus Conclusions. The study findings show that use of a custom-when they wore an unadjusted fitted mouthpiece resulted in improved specific gas exchangemouthguard. The investigator meas- parameters. The authors are pursuing further studies to explainured the participants’ strength by the mechanisms involved in the improved endurance performanceusing a stress gauge kinesiometer, exhibited with mouthpiece use.which measures the amount of pres- Clinical Implications. Dental care professionals have an obli-sure resistance in kilograms of force gation to understand the increasing research evidence in support ofper unit of time. mouthpiece use during exercise and athletic activity and to educate The question remains whether their patients.Smith informed the athletes before Key Words. Mouthpiece; mouthguard; gas exchange; exercise;the study that their performance voluntary oxygen consumption; carbon dioxide.might be affected positively by JADA 2011;142(9):1041-1047.mouthpiece use during testing. IfDr. Garner is an associate professor, Department of Health, Exercise and Sports Science, The Citadel, 171 Moultrie St., Charleston, S.C. 29409,e-mail “”. Address reprint requests to Dr. Garner.Dr. Dudgeon is an assistant professor, Department of Health, Exercise and Sports Science, The Citadel, Charleston, S.C.Dr. Scheett is an assistant professor, Department of Health and Human Performance, College of Charleston, Charleston, S.C.Ms. McDivitt is a research assistant, Department of Health, Exercise and Sports Science, The Citadel, Charleston, S.C. JADA 142(9) September 2011 1041 Copyright © 2011 American Dental Association. All rights reserved.
  4. 4. RESEARCH players assumed that their performance would state exercise. The novel aspect of our research improve, the psychosomatic effect may have was the use of a custom-fitted, unobtrusive caused the reported improvements in muscular mouthpiece rather than the bulky mouthguard strength. used in the study by Francis and Brasher.4 In an effort to measure breathing outcomes Therefore, the purpose of this study was to with a mouthguard, Francis and Brasher4 con- assess the effects of a custom-fitted mandibular ducted a study composed of 10 participants to mouthpiece on gas exchange parameters in assess the physiological effects of mouthguard healthy, college-aged participants. use during five minutes of low-intensity and high-intensity exercise on a cycle ergometer. PARTICIPANTS AND METHODS They found that during the higher-intensity We recruited 16 participants (13 men and three exercise, those wearing a mouthguard exhibited women) aged 18 through 21 years (mean ± improvement in expiratory volume, with signifi- standard deviation [SD] age, 21.2 ± 0.75 years) cant decreases in ventilation (Ve). for this study. Participants’ mean (± SD) height Expanding on the work of Francis and and body mass were 176.37 ± 7.3 centimeters Brasher,4 Garner and McDivitt5 conducted a and 75.20 ± 12.96 kilograms, respectively. The study to determine the effects of mouthpiece use men were physically active and had participated Downloaded from on September 1, 2011 during endurance exercise. In their study, 24 in university-mandated physical exercise, which participants ran at 75 to 85 percent of maximal consisted of a minimum of two cardiovascular heart rate (HR) for 30 minutes on two occasions. and two resistance exercise sessions per week. The investigators assigned mouthpiece use ran- The three women were college athletes, of whom domly to enable them to determine the effects of two were on the track and field team and one mouthpiece use on lactate levels before, during was on the soccer team. All participants and immediately after the protocol. Outcomes reported that they had refrained from physical from this study demonstrated that mouthpiece exercise the day of testing and were free of use had a positive effect on blood lactate levels, injury or illness. which were significantly lower (22.7 percent) at The institutional review board of The Citadel, 30 minutes (4.01 millimoles per liter with Charleston, S.C., approved the study. All partici- mouthpiece use versus 4.92 mmol/L with no pants provided oral and written consent before mouthpiece use).5 participating in the study; we asked them This finding was confirmed in another study whether they understood all of the study’s by Garner and McDivitt,6 the results of which methods and procedures; and we informed them showed that lactate levels were 18.1 percent of their right to drop out of the study at any time. lower after a 30-minute run in the mouthpiece Dental impressions. Before testing, a den- condition versus that in the no-mouthpiece con- tist made impression molds of each participant’s dition (4.41 mmol/L versus 5.21 mmol/L, respec- lower teeth. We then sent the molds to the Bite tively). The study results also showed that Tech laboratory (Danica Beach, Fla.) for fabrica- mouthpiece use had a significant effect on tion of custom-fitted mandibular mouthpieces airway area in 10 participants, as measured by (Under Armour Performance Mouthpiece, computed axial tomography. Specifically, both Under Armour, Baltimore, in cooperation with width and diameter measurements were 9 per- Bite Tech, Minneapolis) (Figure 1). cent greater in participants who wore a mouth- Treadmill runs. Participants performed two piece, with the difference in width measurement 10-minute treadmill runs for each of the three being statistically significant.6 treatment conditions assessed in this study: Because we discovered both anatomical and mouthpiece, no mouthpiece and nose breathing. physiological changes associated with mouth- We assigned the conditions randomly for each piece use during exercise, our goal was to eluci- participant and for each session. We tested each date specific mechanisms involved with this phe- condition on a separate day; thus, participants nomenon. Consequently, we conducted an were required to come to the human perform- investigation to examine possible gas exchange ance laboratory on three occasions. For both of differences associated with wearing a mouth- the 10-minute runs on each day of testing, we piece during steady-state exercise. If partici- pants experienced an improvement in endurance ABBREVIATION KEY. HR: Heart rate. RR: Respira- outcomes (that is, lowered lactate levels), as pre- tory rate. VCO2: Voluntary carbon dioxide produc- vious research findings indicate, then there may tion. Ve: Ventilation. VO2: Voluntary oxygen con- have been some association with improved sumption. VO2 /kg: Voluntary oxygen consumption oxygen/carbon dioxide exchange during steady- per kilogram of body weight. Vt: Tidal volume. 1042 JADA 142(9) September 2011 Copyright © 2011 American Dental Association. All rights reserved.
  5. 5. RESEARCHasked participants to run at 6.5 miles per hourwith 0 percent grade so that we could analyzerespiratory gas levels during steady-state exer-cise. Before the first run on each test day, par-ticipants warmed up by running on the tread-mill for five minutes at 5.0 mph and 0 percentgrade. They then immediately began a 10-minute run at 6.5 mph and 0 percent grade.Afterward, the participants cooled down withthree minutes of walking at 3.0 mph and sevenminutes of seated rest. The second trial of each day was the same asthe first trial, minus the five-minute warm-up.We scheduled conditions two to three days apartduring which participants were allowed to par-ticipate in their normal physical fitness routine, Figure 1. Custom-fitted mandibular mouthpiece (Under Armourbut we did not allow them to exercise on the day Performance Mouthpiece, Under Armour, Baltimore, in coopera- Downloaded from on September 1, 2011of testing. tion with Bite Tech, Minneapolis) worn by college-aged partici- One of us (E.J.M.) attached a face mask to each pants in the study. Image reproduced with permission of Under Armour.participant for each condition and adjusted ituntil she detected no air leaks. We used a meta- ment and exported the data (SigmaStat 3.5,bolic cart (ParvoMedics, Sandy, Utah) to measure Systat, Point Richmond, Calif.) for statisticalvoluntary oxygen consumption (VO2), voluntary analysis. For each of the three conditions, weoxygen consumption per kilogram of body mass grouped and averaged measurements for both(VO2 /kg) and voluntary carbon dioxide production trials for each participant to yield mean values,(VCO2). VO2 is defined as the amount of oxygen in which we used for the statistical analysis. Weliters that the body uses per minute during aer- used analysis of variance (ANOVA) to compareobic exercise.7 VO2 /kg is the amount of oxygen in variables (HR, RR, Vt, Ve, VCO2, VO2 andmilliliters that a person consumes per minute rel- VO2 /kg). We set the significance level at α = .05ative to body mass. VCO2 is the expired byproduct and used a Tukey post hoc analysis of treatmentof metabolism that occurs during aerobic exercise means to identify differences between groups.and is measured in liters per minute. In addition For nonparametric data, we performed ato VO2, VO2 /kg and VCO2, we measured partici- Kruskal-Wallis ANOVA on ranks and used thepants’ respiratory rate (RR) (number of breaths Dunn method for post hoc analysis. All valuesper minute), tidal volume (Vt) (amount of air are expressed as mean ± SD. We did not performinspired and expired per breath), Ve (total volume any ancillary analyses.of inspired and expired air per minute) and HRby using the metabolic cart. RESULTS We measured these parameters every five sec- Data from two of the 16 participants wereonds and averaged the measurements for each incomplete; thus, results for this study areminute of the 10-minute run for all three condi- based on data from 14 participants. As shown intions. On all test days, we calibrated the meta- Figures 2 through 4, VO2, VO2 /kg and VCO2bolic cart according to the manufacturer’s speci- were statistically significantly (P < .05) higherfications. For the mouthpiece condition (group in participants in group 1 than in participants1), we asked participants to bite down on the in groups 2 and 3 during the 10-minute trial,custom-fitted mouthpiece and breathe through and they were higher in participants in group 2their mouths while their noses were clamped than in participants in group 3. The resultswith a metal clamp attached to the face mask. were similar for minutes 1 through 5 (Table 1,For the no-mouthpiece condition (group 2), we page 1045). During minutes 6 through 10,asked participants to breathe through their open VCO2, VO2 and VO2 /kg were significantlymouths while their noses were clamped. For the (P < .05) higher in participants in group 1 thannose-breathing condition (group 3), we taped in participants in groups 2 and 3 (Table 2, pageparticipants’ mouths shut, which forced them to 1045). The results showed no differencesbreathe through their noses. (P > .05) in Ve, RR or Vt between groups 1 and Statistical analysis. One of us (T.P.S.) 2; however, as expected, the results for groups 1entered all data into a spreadsheet (Excel, and 2 were statistically significantly differentMicrosoft, Redmond, Wash.) for data manage- (P < .05) from those for group 3 during the entire JADA 142(9) September 2011 1043 Copyright © 2011 American Dental Association. All rights reserved.
  6. 6. RESEARCH 2.6 10-minute test (Table 3, page 1046), during min- VOLUNTARY OXYGEN CONSUMPTION * utes 1 through 5 (Table 1) and during minutes 6 2.4 through 10 (Table 2). Finally, we found no differ- 2.2 ences in HR at any time points between all * (LITERS/MINUTE) † three conditions (Tables 1 through 3). 2.0 1.8 DISCUSSION 1.6 Athletes and others have worn mouthpieces † during sports as protective devices against dental 1.4 injuries and concussions. The American Dental 1.2 Association’s Council on Access, Prevention and Interprofessional Relations and Council on Scien- 1.0 1 (Mouthpiece) 2 (No Mouthpiece) 3 (Nose Breathing) tific Affairs8 concluded that mouthguards provide GROUP a protective effect against hard-tissue or soft- tissue damage in the mouth (such as tooth frac- Figure 2. Voluntary oxygen consumption during steady-state tures, lip lacerations and mandibular damage). exercise. Asterisk indicates statistically significant difference (P < .05) from group 3. Dagger indicates statistically significant differ- However, increased use of mouthpieces for per- Downloaded from on September 1, 2011 ence (P < .05) from group 1. formance enhancement is a recent trend in sport and exercise. In a study of mouthpiece use 35 during endurance exercise, Garner and McDi- VOLUNTARY OXYGEN CONSUMPTION * vitt5,6 reported lower lactate levels in participants (MILLILITERS/KILOGRAM/MINUTE) 30 who wore a mouthpiece compared with levels in † those who did not wear a mouthpiece. Thus, the 25 purpose of this study was to explain the lower 20 † lactate levels observed with mouthpiece use during exercise by elucidating the oxygen/carbon 15 dioxide differences with mouthpiece use. 10 Increases in VCO2 would suggest an improved ability to buffer the hydrogen ion associated with 5 lactate, thereby lowering hydrogen in the blood and subsequent lactate levels. 0 1 (Mouthpiece) 2 (No Mouthpiece) 3 (Nose Breathing) Respiratory gas exchange. To elucidate GROUP the potential mechanisms involved with mouth- piece use during exercise, we assessed the pat- Figure 3. Voluntary oxygen consumption per kilogram of body weight during steady-state exercise. Asterisk indicates statistically terns of respiratory gas exchange in a mouth- significant difference (P < .05) from group 3. Dagger indicates sta- piece condition, a no-mouthpiece condition and a tistically significant difference (P < .05) from group 1. nose-breathing condition. Previous researchers in the area of airway dynamics have reported differences between nasal and mouth breathing VOLUNTARY CARBON DIOXIDE PRODUCTION 2.4 during various intensities of exercise.9-12 Specifi- * cally, these authors found better gas exchange 2.2 with mouth breathing than with nasal * breathing. Consequently, we expected to find 2.0 † lower Vt, VO2, VO2 /kg, VCO2 and RR with nasal (LITERS/MINUTE) 1.8 breathing because these results have been reported in previous research.9-12 1.6 However, we observed a novel finding when 1.4 comparing mouth breathing with no mouthpiece † use to mouth breathing with mouthpiece use. 1.2 We had hypothesized that mouth breathing in the no-mouthpiece condition would elicit out- 1.0 1 (Mouthpiece) 2 (No Mouthpiece) 3 (Nose Breathing) comes similar to those in the mouth-breathing- GROUP with-mouthpiece condition; however, this was not the case. Specifically, the results showed sig- Figure 4. Voluntary carbon dioxide production during steady- nificant improvements in VCO2 and oxygen state exercise. Asterisk indicates statistically significant difference (P < .05) from group 3. Dagger indicates statistically significant parameters and no significant differences in Ve difference (P < .05) from group 1. when participants wore the mouthpiece versus 1044 JADA 142(9) September 2011 Copyright © 2011 American Dental Association. All rights reserved.
  7. 7. RESEARCHwhen they did not TABLE 1wear the mouthpiece Data from minutes 1 though 5 of steady-stateduring the entire 10-minute test; during exercise.minutes 1 through 5; VARIABLE MEAN (± STANDARD DEVIATION) MEASUREand during minutes 6 Group 1 Group 2 Group 3through 10. Thus, the (Mouthpiece) (No Mouthpiece) (Nose Breathing Only)improvements in VCO * (L†/Minute) 2 2.00 ± 0.55‡ 1.66 ± 0.49‡§ 1.02 ± 0.53VCO2 and oxygen VO ¶ (L/Minute) 2.21 ± 0.64‡ 1.73 ± 0.54‡§ 1.12 ± 0.57parameters cannot be 2 # (mL ** /kg/Minute) VO /kg 29.1 ± 6.7 ‡ 22.5 ± 4.8 ‡§ 15.2 ± 7.3explained by 2improved Ve with Ventilation (L/Minute) 49.7 ± 10.8‡ 50.4 ± 12.1‡ 29.8 ± 8.5mouthpiece use. Respiratory Rate 31 ± 7‡ 32 ± 8‡ 25 ± 6 (Breaths/Minute) Francis andBrasher4 assessed the Tidal Volume (L) 2.10 ± 0.61‡ 2.09 ± 0.59‡ 1.60 ± 0.59physiological effects Heart Rate (Beats/Minute) 157 ± 15 156 ± 15 154 ± 11of mouthguard use * VCO : Voluntary carbon dioxide production. Downloaded from on September 1, 2011 2during five minutes † L: Liters. ‡ Statistically significant difference (P < .05) from group 3 (nose breathing only).of low- and high- § Statistically significant difference (P < .05) from group 1 (mouthpiece).intensity exercise on ¶ VO : Voluntary oxygen consumption. 2a cycle ergometer. For # VO /kg: Voluntary oxygen consumption per kilogram of body weight. 2 ** mL: Milliliters.the low-intensitycycling, 10 men TABLE 2cycled at 100 wattsand seven women Data from minutes 6 through 10 of steady-statecycled at 75 W; for exercise.the high-intensity VARIABLE MEAN (± STANDARD DEVIATION) MEASUREcycling, men cycled at Group 1 Group 2 Group 3150 W and women (Mouthpiece) (No Mouthpiece) (Nose Breathing Only)cycled at 125 W. VCO * (L†/Minute) 2.29 ± 0.59‡ 1.88 ± 0.54‡§ 1.19 ± 0.64 In comparing our 2 ¶ (L/Minute)study results with VO 2 2.43 ± 0.73 ‡ 1.90 ± 0.60 ‡§ 1.31 ± 0.74those of Francis and VO /kg# (mL**/kg/Minute) 2 31.9 ± 7.5‡ 24.8 ± 5.8§ 18.0 ± 10.5Brasher,4 we should Ventilation (L/Minute) 56.9 ± 11.5‡ 58.3 ± 13.7‡ 34.3 ± 11.0note a difference in Respiratory Rate 33 ± 7‡ 35 ± 8‡ 28 ± 8VO2 /kg between the (Breaths/Minute)two studies. Francis Tidal Volume (L) 2.28 ± 0.63‡ 2.25 ± 0.63‡ 1.68 ± 0.66and Brasher4 re- Heart Rate (Beats/Minute) 169 ± 16 167 ± 16 169 ± 10ported a decreased * VCO : Voluntary carbon dioxide production.volume of VO2 /kg † L: Liters. 2with mouthguard use ‡ Statistically significant difference (P < .05) from group 3 (nose breathing only).during high-intensity § Statistically significant difference (P < .05) from group 1 (mouthpiece). ¶ VO : Voluntary oxygen consumption.exercise, whereas we 2 # VO /kg: Voluntary oxygen consumption per kilogram of body weight. 2measured a signifi- ** mL: Milliliters.cant increase inVO2 /kg when participants wore the mouthpiece. ticipants in our study wore a custom-fitted man-However, Francis and Brasher4 also noted that dibular mouthpiece that did not create anyparticipants reported a feeling of restricted air- obstruction in breathing.flow with mouthguard use, whereas the partici- The results of these studies were similar withpants in our study did not report feeling such a regard to Ve, VCO2 and VO2 parameters withrestriction. We believe the differences between and without mouthguard or mouthpiece use.our study results and those reported by Francis During the high-intensity protocol, Francis andand Brasher4 most likely are attributable to the Brasher4 found an improvement in expiratorytype of mouthpiece worn in each study. In the volume, with decreases in Ve with mouthguardstudy by Francis and Brasher,4 participants use; these results are similar to those of ourwore one of three different over-the-counter, study. Francis and Brasher4 suggested thatunfitted maxillary mouthguards, whereas par- when participants wore a mouthguard, they JADA 142(9) September 2011 1045 Copyright © 2011 American Dental Association. All rights reserved.
  8. 8. RESEARCH TABLE 3 breathes through the Data from minutes 1 through 10 of steady-state mouth versus when one does not wear a exercise. mouthpiece and VARIABLE MEAN (± STANDARD DEVIATION) MEASURE breathes through the Group 1 Group 2 Group 3 mouth. Thus, the (Mouthpiece) (No Mouthpiece) (Nose Breathing Only) improved airway Ventilation (L*/ Minute) 53.4 ± 11.0† 54.6 ± 12.8† 32.3 ± 9.9 dynamics we found in Respiratory Rate 32 ± 7† 34 ± 8†‡ 26 ± 7 our study may be (Breaths/ Minute) explained in part by Tidal Volume (L) 2.16 ± 0.62† 2.14 ± 0.61† Not applicable anatomical and neu- romuscular changes Heart Rate (Beats/Minute) 163 ± 15 162 ± 16 161 ± 11 that occur during * L: Liters. exercise with custom- † Statistically significant difference (P < .05) from group 3 (nose breathing only). ‡ Statistically significant difference (P < .05) from group 1 (mouthpiece). fitted mouthpiece use as the mouthpiece might have been using a type of breathing called affects the genioglossus. Downloaded from on September 1, 2011 “pursed lip breathing,” which they defined as Cortisol and epinephrine. We also reported pursing one’s lips and breathing out deeply. This that the use of a custom-fitted mandibular type of breathing has been linked to improved mouthpiece is associated with a decrease in the respiratory measures such as reduced breathing stress hormone cortisol after high-intensity exer- rates and increased Vt in people with respiratory cise.24 This finding is consistent with the findings disorders, but it has not been studied exten- of Hori and colleagues,25 who reported a decrease sively in a healthy population.13-15 in corticotrophin-releasing factor levels (stress- We propose that a similar, but more plau- induced response of the hypothalamic-pituitary- sible, mechanism may have occurred when par- adrenal axis and a precursor to corticosterone ticipants wore the custom-fitted mandibular release, the rat equivalent to cortisol in humans) mouthpiece. We asked participants to bite down in rats that were allowed to bite down on a on the mouthpiece, which has two wedges (one wooden stick while experiencing a stressor. If on either side of the mouthpiece) that create an biting down on the mouthpiece results in a opening between the maxillary and mandibular decrease in cortisol levels, it stands to reason teeth (Figure 1). In addition, according to the that it also would affect other stress-related hor- product description,16 this mouthpiece shifts the mones, namely epinephrine. Epinephrine is mandible down and into a more forward posi- released quickly in response to a stressor, and tion, which Garner and McDivitt6 reported one of its many functions is to stimulate the gly- resulted in increased airway openings. colytic process (that is, breaking down of glucose Genioglossus muscle. We also propose a to provide energy) to increase the rate of energy contribution from a neuromuscular response production. Two of the key byproducts of glycol- that occurs when participants bite down on the ysis are lactate and CO2. We have shown that use mouthpiece and breathe through the mouth. of the custom-fitted mouthpiece decreases lactate What might have occurred, and which some par- production and increases VCO2 production. We ticipants reported anecdotally, is that when a now believe that a decrease in epinephrine participant bit down on the mouthpiece and release may be the reason for these observed breathed during steady-state exercise, the changes; however, more research is needed. tongue moved forward, resulting in a contrac- Thus, if an anatomical and neuromuscular tion of the genioglossus muscle. The results of improvement in airway dynamics occurs along extensive research regarding the genioglossus with a diminished stress response (that is, lower muscle show that contraction of this muscle cortisol and epinephrine levels) with mouthpiece leads to relaxation of the pharyngeal airway, use during steady-state exercise, this could thereby improving airway dynamics.17-22 explain the improved oxygen and carbon dioxide Remmers23 reported that the genioglossus kinetics, as well as the improvements in lactate may be associated with a reflex that leads to the production, that the results of our study show. dilation of the pharyngeal area, thereby aiding in respiration in both humans and animals. Pre- CONCLUSION liminary research in our laboratory has shown The results of this study show improved airway differences in electromyographic activity of the dynamics in participants who wore a custom- genioglossus when one wears a mouthpiece and fitted mandibular mouthpiece during steady- 1046 JADA 142(9) September 2011 Copyright © 2011 American Dental Association. All rights reserved.
  9. 9. RESEARCHstate exercise. The improvements in gas guards. Br J Sports Med 1991;25(4):227-231. 5. Garner DP, McDivitt EJ. The effects of mouthpiece use duringexchange and Ve observed with mouthpiece use endurance exercise on lactate and cortisol levels. Med Sci Sportsmay explain the physiological outcomes of Exerc 2009;41(5):S448improved lactate levels during endurance run- 6. Garner DP, McDivitt E. Effects of mouthpiece use on airway openings and lactate levels in healthy college males. Compendning, as reported previously.5,6 Specifically, Contin Educ Dent 2009;30(special no. 2):9-13.improved VCO2 exhalation, as observed with 7. Beam WC, Adams GM. Exercise Physiology Laboratory Manual. 6th ed. New York City: McGraw Hill; 2011.mouthpiece use throughout the 10-minute 8. ADA Council on Access, Prevention and Interprofessional Rela-treadmill protocol, leads to improved buffering tions; ADA Council on Scientific Affairs. Using mouthguards toof hydrogen ion levels, which, in turn, decreases reduce the incidence and severity of sports-related oral injuries. JADA 2006;137(12):1712-1720.lactate levels during endurance exercise. This 9. Camner P, Bakke B. Nose or mouth breathing? Environ Resexplanation is consistent with the differences in 1980;21(2):394-398.VCO2 observed in this study (21.0 percent 10. Chinevere TD, Faria EW, Faria IE. Nasal splinting effects on breathing patterns and cardiorespiratory responses. J Sports Scihigher with mouthpiece use than without 1999;17(6):443-447.mouthpiece use), as well as with differences in 11. Fregosi RF, Lansing RW. Neural drive to neural dilator mus- cles: influence of exercise intensity and oronasal flow partitioning.lactate levels observed in a previous study (22.7 J Appl Physiol 1995;79(4):1330-1337.percent lower with mouthpiece use than that 12. Saibene F, Mognoni P, Lafortuna CL, Mostardi R. Oronasalwithout mouthpiece use).5 breathing during exercise. Pflugers Arch 1978;378(1):65-69. Downloaded from on September 1, 2011 13. Dechman G, Wilson CR. Evidence of underlying breathing In addition, the improvement in oxygen retraining in people with sta ble chronic obstructive pulmonary dis-kinetics during the beginning of the exercise pro- ease. Phys Ther 2004;84(12):1189-1197.tocol (that is, minutes 1 through 5), as demon- 14. Faager G, Stâhle A, Larsen FF. Influence of spontaneous pursed lips breathing on walking endurance and oxygen saturationstrated by the significantly higher VO2 and in patients with moderate to severe chronic obstructive pulmonaryVO2 /kg levels in participants in group 1 (the disease. Clin Rehabil 2008;22(8):675-683. 15. Tiep BL. Pursed lips breathing: easing does it. J Cardiopulmmouthpiece condition), also may affect initial Rehabil Prev 2007;27(4):245-246.oxygen deficit (defined as the amount of oxygen 16. Under Armour. Armourbite technology. “ for exercise and actual oxygen consump- shop/us/en/accessories”. Accessed Aug. 8, 2011. 17. Bailey EF, Huang YH, Fregosi RF. Anatomic consequences oftion26). At the beginning of exercise, there is a lag intrinsic tongue muscle activation. J Appl Physiol 2006;101(5):of approximately one to two minutes during 1377-1385.which oxygen is transported to the skeletal mus- 18. Cheng S, Butler JE, Gandevia SC, Bilston LE. Movement of the tongue during normal breathing in awake healthy humans. J Physiolcles. Therefore, one theory of how the mouth- 2008;586(part 17):4283-4294.piece may affect lactate levels is by decreasing 19. Fogel RB, Trinder J, Malhotra A, et al. Within-breath control of genioglossal muscle activation in humans: effect of sleep-wake state.the time for oxygen to reach the muscle being J Physiol 2003;550(part 3):899-910.exercised, thereby decreasing fatigue during 20. Mann EA, Burnett T, Cornell S, Ludlow CL. The effect of neu-endurance exercise.27 Further research is needed romuscular stimulation of the genioglossus on the hypopharyngeal airway. Laryngoscope 2002;112(2) fully elucidate the physiological mechanisms 21. Sokoloff AJ. Activity of tongue muscles during respiration: itinvolved in improved performance when one takes a village? J Appl Physiol 2004;96(2):438-439.wears a custom-fitted mouthpiece. I 22. Blumen MB, Perez de La Sota A, Quera-Salva MA, Frachet B, Chabolle F, Lofaso F. Genioglossal electromyogram during main- Disclosure. Dr. Garner and Ms. McDivitt received honoraria from tained contraction in normal humans. Eur J Appl Physiol 2002;Bite Tech, Minneapolis. 88(1-2):170-177. 23. Remmers JE. Wagging the tongue and guarding the airway: The authors thank Michael Engel, DDS (Charleston, S.C.), for reflex control of the genioglossus. Am J Respir Crit Care Med 2001;making the models of the mouthpiece and Bite Tech Laboratories 164(11):2013-2014.(Dania Beach, Fla.) for supplying the custom-fitted mouthpieces to 24. Garner DP, Dudgeon WD, McDivitt E. The effects of mouth-each participant. piece use on cortisol levels during an intense bout of resistance exer- cise. J Strength Cond Res. In press. 1. Garabee WF Jr. Craniomandibular orthopedics and athletic per- 25. Hori N, Yuyama N, Tamura K. Biting suppresses stress-formance in the long distance runner: a three year study. Basal Facts induced expression of corticotropin-releasing factor (CRF) in the rat1981;4(3):77-81. hypothalamus. J Dent Res 2004;83(2):124-128. 2. Smith SD. Muscular strength correlated to jaw posture and the 26. Wilmore JK, Costill DL, Kenney WL. Physiology of Sport andtemporomandibular joint. N Y State Dent J 1978;44(7):278-285. Exercise. 4th ed. Champaign, Ill.: Human Kinetics; 2007. 3. Smith SD. Adjusting mouthguards kinesiologically in profes- 27. Kilding AE, Winter EM, Fysh M. Moderate-domain pulmonarysional football players. N Y State Dent J 1982;48(5):298-301. oxygen uptake kinetics and endurance running performance. 4. Francis KT, Brasher J. Physiological effects of wearing mouth- J Sports Sci 2006;24(9):1013-1022. JADA 142(9) September 2011 1047 Copyright © 2011 American Dental Association. All rights reserved.
  10. 10. !
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
  12. 12. !
  13. 13. The Effects Of Mouthpiece Use During EnduranceExercise On Lactate And Cortisol Levels: 2416: Board#61 May 29 9:00 AM - 10:30 AMGarne, Dena P.; McDivitt, EricaMedicine & Science in Sports & Exercise . 41(5) Supplement 1:339, May 2009.doi: 10.1249/01.MSS.0000355581.74244.c0Author InformationThe Citadel, Charleston, SC.(No relationships reported)Protective mouthpieces have been used in a variety of sports to decrease the risk oforofacial injury. However, there is limited research on the physiological effects ofmouthpiece use during exercise.PURPOSE: To investigate the possible effect on lactate and cortisol levels when wearingand not wearing a mouthpiece, the wEdge (Bite-Tech Corp).METHODS: Subjects (n=24), age 18-24, ran at 75 -85% of their maximal heart rate for30 minutes on 2 separate trials, being randomly assigned the use of the mouthpiece on 1of the 2 trials. Lactate levels were assessed before, 15 and 30 minutes during, and post 10minutes exercise. Subjects provided a passive drool sample before and after each exercisebout to assess salivary cortisol levels.RESULTS: Lactate data indicated a significant difference between wearing and notwearing the mouthpiece at 30 minutes exercise (p-value = 0.024). Mean lactate levels at30 minutes with the mouthpiece was 4.01 mmol/L versus 4.92 mmol/L without themouthpiece. Mean cortisol levels showed no significant difference between wearing andnot wearing the mouthpiece (p-value= 0.111). However, there was a trend towards lowermean cortisol levels with use of the mouthpiece (0.1484 ug/dL) versus no mouthpiece(0.2201 ug/dL).CONCLUSION: This study suggests that use of a mouthpiece may reduce lactate andcortisol increases and thereby improve exercise performance.©2009The American College of Sports Medicine!
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
  16. 16. July/August 2009 — Vol. 30 (Special Issue 2)A Supplement to of Continuing Education in Dentistry ® Published by AEGIS Publications, LLC © 2009
  17. 17. RESEARCH UPDATE Effects of Mouthpiece Useon Airway Openings and Lactate Levels in Healthy College Males Dena P. Garner, PhD;1 and Erica McDivitt, MS2Abstract: Research has described the use of mouthpieces not only in preventing oral-facial injuries, but linking use toimprovements in muscular strength and endurance. However, the mechanisms by which these improvements occur havenot been elucidated. The purpose of this study was to understand possible physiological explanations for improvementsin exercise performance with the use of a mouthpiece. Specifically, this study focused on differences in lactate levels after30 minutes of endurance exercise with and without a mouthpiece. In addition, computed tomography (CT) scans weretaken of the cross-sectional area of the oropharynx in each participant (N = 10) with and without a mouthpiece. CT scansshowed a significant difference in mean width (28.27 mm with the mouthpiece vs 25.93 mm without the mouthpiece,P = .029) and an increase in mean diameter with a mouthpiece (12.17 mm vs 11.21 mm, P = .096). Lactate levels werelowered with the mouthpiece at 1.86 mmol/L vs 2.72 mmol/L without mouthpiece. This research suggests that there isan improvement in endurance performance that may be linked to improved airway openings resulting from the use of amouthpiece. Future studies should continue to clarify the possible mechanisms for these exercise outcomes as well as tounderstand the optimal mandibular advancement to elicit these exercise improvements.M outhpieces have been used for a variety of con- While there is compelling research to support the use of tact sports to prevent oral-facial injury.1 In a mouthguards to protect against oral-facial injuries during review of dental trauma literature, Glendor2 contact sports, there is also research to suggest that mouth-noted that participation in sports is the greatest cause of pieces may enhance performance. Smith6,7 noted that pro-dental injuries. To minimize injury associated with contact fessional football players exhibited greater arm strength withsport participation, the American Dental Association (ADA) properly fitted mouthguards that resulted in changes in biterecommends the use of mouthguards to protect against patterns. Smith also noted that those players with the mostdental trauma during contact sports.3 In addition to the extreme overbite corrected with a mouthguard experiencedrecommendation of the ADA, such sport-governing bodies the greatest increase in strength. Specifically, he observedas the National Alliance of Football Rules Committee have that with a properly adjusted mouthguard, 66% of the play-mandated mouthguards for use in high school football in ers exhibited significant strength improvements on the iso-the United States.4 The 2008-2009 National Athletic As- metric deltoid press.7 He stated that the increase in strengthsociation (NCAA) Sports Medicine Handbook mandates with a properly fitted mouthguard was because of decreasedmouthguards for athletes involved with football, field hock- pressure in the temporomandibular joint (TMJ).ey, lacrosse, and ice hockey in order to minimize dental Not only has improvement in strength been noted, buttrauma during these sports.5 Garabee8 described improvement in 7 runners’ endurance1Assistant Professor, Department of Health, Exercise and Sport Science, The Citadel, Charleston, South Carolina2Research Assistant, Department of Health, Exercise and Sport Science, The Citadel, Charleston, South Carolina Compendium—Volume 30 (Special Issue 2) 9
  18. 18. Research Update—Lactate Levelsand recovery with use of a mouthpiece to promote proper oc- With this data suggesting a physiological improvementclusion. He observed that when runners wore a wax bite when a mouthpiece is used, the next step was to clarify fur-mouthpiece, there was an increase in mileage: 64 to 100 miles ther the possible reasons for this improvement. Trenouthper week in one runner, and 50 to 80-100 miles per week in and Timms 13 found a positive association between theanother. He also noted quicker recovery times and decreased orpharyngeal airway opening and mandibular length, withperceived exertion with use of the mouthpiece vs without the a narrower opening associated with a shorter mandibularmouthpiece. Garabee hypothesized that this improvement length. They cited previous research that suggested repo-was because of decreased stress with mouthpiece use that sitioning the mandible in an anterior position, therebyreduced clenching and grinding of teeth during exercise. opening airways and promoting respiratory gas exchange As the research evolved, the to and from the lungs. In the litera-possible reasons for improvements ture associated with sleep apneain performance were elucidated THIS PRESENT STUDY SUGGESTS (where airway openings are dimin-by Francis and Brasher. 9 In a ished during sleep) and mouth-study of 10 men and 7 women, MECHANISMS BY WHICH pieces, it can be noted that therethey found that wearing a mouth- is significant improvement in air- LACTATE PRODUCTION MAYpiece during 20 minutes of high way openings for patients wear-intensity cycling resulted in im- BE IMPROVED WITH INCREASED ing a mouthpiece (a device thatprovements in ventilation (average fits like a retainer and forces theof 43.13 l/min with mouthpiece AIRWAY OPENINGS, THEREBY lower teeth to relax in a forwardvs 50.98 l/min without mouth- IMPROVING OXYGEN KINETICS position). Kyung and colleagues14piece). They noted that this im- advanced the mandible forwardprovement may be from pursed SUCH AS LOWERED OXYGEN with an oral appliance in 12lips breathing which results in DEFICIT AND/OR IMPROVED sleep apnea patients and found agreater oxygen saturation. Ugalde reduction of the apnea-hypop-and colleagues10 confirmed that BREATHING WORK RATES. nea index from 44.9 (withoutpursed lips breathing resulted in appliance) to 10.9 (with appli-increased oxygen saturation in ance). Gale and colleagues15 alsomyotonic muscular dystrophy patients, while Tiep 11 stated found a significant improvement in mean airway openingthat such breathing results in increased tidal volume, car- with an anterior mandibular device while patients werebon dioxide removal, and oxygen saturation. supine in a conscious state. Specifically, Gale et al15 found Drawing from the research by Frances and Brasher, 9 the that in 32 participants, the mean minimal pharyngeal cross-possible reasons for improvements in endurance perform- sectional area was increased 28 mm2 with the mouthpieceance while wearing a mouthpiece provide insight into the vs without the mouthpiece. Gao and collegues16 statedphysiological mechanisms that may be occurring. In order that for their participants, the mandibular advancement wasto first understand if there were improvements in perform- 7.5% with a mouthpiece. They specifically found a signifi-ance, the authors’ laboratory conducted a series of pilot cant opening of the oropharynx (P = .0258) and velo-studies primarily to determine if lactate levels were affect- pharynx areas (P = .006). Zhao et al17 also found that theed by the use of a mouthpiece. If, as Frances and Brasher9 velopharynx opening increased significantly with an ad-suggested, there was improvement in ventilation (ie, in- justable mandibular custom mouthpiece, from 3.27 mm2creased oxygen saturation and removal of carbon diox- at 0 mm, to 8.45 mm 2 at 2 mm, 17.73 mm 2 at 4 mm,ide), then there could consequently be an improvement 24.45 mm2 at 6 mm, and 35.82 mm2 at 8 mm. This re-in lactate levels. The authors found that with 24 partici- search suggests that the positioning of the mouthpiece willpants, there was improvement in lactate levels after 30 min- impact the degree of airway opening, with greater movementutes of running on a treadmill at 85% of maximal heart rate of mandible in a forward position resulting in a greater open-(4.01 mmol/L with mouthpiece vs 4.92 mmol/L without ing of the velopharynx. With the findings of previous stud-mouthpiece).12 ies as well as those in the authors’ laboratory, the hypothesis10 Compendium—Volume 30 (Special Issue 2)
  19. 19. Garner and McDivittof this study is that there will be increased airway openingand a decrease in lactate levels with the use of a mouthpiece. 30 25 MouthpieceMETHODS 20 Millimeters No MouthpieceFor this pilot study the authors recruited 10 participants to 15determine if there were differences in airway openings with 10the use of a mouthpiece and if there were differences in lac- 5tate levels after 30 minutes of running. The mouthpiece 0used was a boil and bite upper mouthpiece which had a Width Diametergreater bite opening distal vs proximal (EDGE, Bite Tech Figure 1 Mean values of oropharynx width and diameterInc, Minneapolis, MN). Participants were 18–21 years old, with and without a mouthpiece.male, and from The Citadel. Each participant completed acomputed tomography scan (i-CAT 3D Dental Imaging 3.0System, Imaging Sciences International, Hatfield, PA) with Lactate levels (mmol/L) 2.5and without a mouthpiece, and the mean oropharynx area Mouthpiecewas measured in each. Participants then completed two 2.0 No Mouthpiece30 minute runs on the treadmill at 75%–85% of their 1.5maximum heart rate, and lactate levels were assessed at 0, 1.015, and 30 minutes of the run (Accutrend Lactate Ana- 0.5lyzer, Sports Resource Group, Inc, Minneapolis, MN). Par- 0ticipants were randomly assigned a mouthpiece during each Mean of Participants (N = 10)running trial and were required to refrain from exercising Figure 2 Mean lactate levels after 30 minutes of running atthe day before and the day of testing. If participants failed 75%–85% of maximum heart cooperate, they were asked to return on a subsequent daywhen compliance was met. oral appliance. Kyung et al14 also found reduced apnea- hypopnea indices, reducing the average index from 44.9 toRESULTS 10.9 with an oral appliance.The results of this study displayed a significant increase in Research continues to elucidate the degree of forwardmean width value of the oropharynx at 28.27 mm with the movement which would be most beneficial. In the researchmouthpiece vs 25.93 mm without the mouthpiece (P = .029) by Zhao and colleagues17 there was a range of improvement(Figure 1). In addition, the mean value of the diameter was in the airway opening for participants: as the mandible wasincreased with a mouthpiece vs without a mouthpiece moved to a more forward position, the opening of the air-(12.17 mm vs 11.21 mm, P = .096) (Figure 1). As previous way increased. It should also be noted that a specific mouth-studies had suggested, the difference in lactate levels from piece was used for this present study. This particularpre- to post-exercise was lowered with the mouthpiece vs mouthpiece offered minimal obstruction for the partici-without the mouthpiece, though not at the level of signif- pants as they ran, yet was also designed to bring the man-icance (1.86 mmol/L with mouthpiece vs 2.72 mmol/L dible to a forward position. The mouthpiece was easy towithout mouthpiece) (Figure 2). use and mold to participants, who noticed no impairment in their breathing patterns during use. Further research toDISCUSSION understand how different mouthpieces could affect the air-There is a plethora of research to suggest that the upper air- way openings is warranted. Such studies should focus onway of patients with sleep apnea is improved with a custom- measuring the movement of the mandible with the use of afit oral device, due specifically to the forward movement of mouthpiece and how this may affect airway openings inthe mandible.13-18 Ryan and colleagues18 found improve- healthy participants.ment in the cross-sectional area of the velopharynx and in The results of the study suggest that the use of a mouthpiecethe apnea index with the use of a mandibular advancement increases airway openings in these healthy participants and Compendium—Volume 30 (Special Issue 2) 11
  20. 20. Research Update—Lactate Levelsthat the use of a mouthpiece while exercising may improve exercise intensity, the glycolytic pathway is highly utilized tolactate levels. While previous studies with sleep apnea popu- meet energy needs. The end product of this pathway is thelations indicated improvements in airway openings with production of lactic acid. Lactic acid is broken down intothe use of a mouthpiece, there were limited data on a lactate and hydrogen ions, and it is this increase of hydro-younger, healthy population (age 21 +/- 1.1 years). This gen ions that is negatively associated with metabolic proc-study, however, is similar in a study by Gao and col- esses, leading to fatigue.19-20 Thus, any mechanism whichleagues16 which took magnetic images of 14 healthy Japa- elicits lowered hydrogen levels resulting from lactic acidnese men (age 27.7 +/- 1.9 years). Gao et al16 saw improve- should increase an athlete’s time to fatigue. For example, ifments in airway opening with a custom-fit oral device that the pathways used during exercise rely more on oxygen,was specifically designed to move the mandible in a more then lactate levels will be lowered. Yet understanding thisforward position. Their study found significant improve- link between lowered lactate levels and increased airwayments in the velopharynx (P = .0006) and the oropharynx openings is a complex issue needing further investigation.12(P = .0258), while the current study noted a significant im- Previous studies have noted that an improvement inprovement in the oropharynx width (P = .029). breathing work rates leads to improved exercise time be- Because of the financial costs of obtaining 2 CT scans cause of reduced oxygen uptake and ventilation.21-22 Spe-for each participant, this study was limited in the number cifically, if breathing mechanics are improved, then there isof participants. In addition, this was designed as a pilot a decreased need for oxygen and blood flow by the respira-study to determine: 1) if there were changes in airway tory muscles which typically require approximately 10% ofopenings with a mouthpiece in healthy participants; and the oxygen needs during strenuous exercise. Less blood2) if this could translate into lowered lactate levels. The flow to the respiratory muscles suggests an increase ofresults suggest there may be a link, which could be one pos- blood flow to the exercising skeletal muscles, which wouldsible physiological explanation for performance improve- prolong time to fatigue. Specifically, Harms and colleaguesment with a mouthpiece. found that when respiratory muscle work was decreased It may be surmised that the lack of significant differ- (via a proportional-assist ventilator), time to exercise ex-ences in lactate levels in this study may be because of the haustion was increased in 76% of the trials by an averagelow number of subjects, even though the trend was lower of 1.3 minutes (+/-0.4 minutes).22lactate levels with the mouthpiece vs no mouthpiece. As Improvement in respiratory muscle function may notthe authors’ previous study suggested (N = 24), lactate lev- be the only mechanism that occurs during mouthpieceels were significantly lower with a mouthpiece vs without a use. An interesting study by Kilding and colleagues23 exam-mouthpiece after 30 minutes of running on a treadmill ined response time of oxygen kinetics in endurance runners(4.01 mmol/L mouthpiece vs 4.92 mmol/L no mouth- (N = 36) to understand its possible effect on a 5 kilometerpiece) (Figure 3). time trial. An important finding from their study was that Research has consistently noted the correlation between a faster phase II oxygen uptake kinetic response at the on-exercise fatigue and higher lactate levels. As one increases set of moderate intensity exercise resulted in faster 5 kilo- meter performance. Thus, they concluded that those runners who had a shorter oxygen deficit at the onset of exercise (as 6 indicated by shortened phase II response) could increase Lactate levels (mmol/L) 5 Mouthpiece time to exhaustion, as indicated by the better 5 kilometer 4 performance. Kilding cited previous work by Casaburi and No Mouthpiece 3 colleagues24 stating a decrease in oxygen deficit at the onset 2 of exercise could result in decreased lactate production, 1 which could potentially improve endurance performance. 0 This present study suggests mechanisms by which lactate Mean of Participants (N = 24) production may be improved with increased airway open-Figure 3 Mean lactate levels after 30 minutes of running at ings, thereby improving oxygen kinetics such as lowered85% of maximum heart rate. oxygen deficit and/or improved breathing work rates.12 Compendium—Volume 30 (Special Issue 2)
  21. 21. Garner and McDivittCONCLUSION 9. Francis KT, Brasher J. Physiological effects of wearing mouth-This study found that the use of a mouthpiece significant- guards. Br J Sports Med. 1991;25(4) improves airway openings in participants as compared 10.Ugalde V, Breslin EH, Walsh SA, et al. Pursed lips breathingwith these same participants who do not wear the mouth- improves ventilation in myotonic muscular dystrophy. Archpiece. In addition, lactate levels are improved when partici- Phys Med Rehabil. 2000;81(4):472-478.pants wear the mouthpiece vs when they do not wear the 11.Tiep BL. Pursed lips breathing—easing does it. J Cardiopulmmouthpiece. One explanation for the decrease in lactate Rehabil Prev. 2007;27(4):245-246.levels may be an improvement in oxygen kinetics at the 12.Garner DP, McDivitt E. The effects of mouthpiece use on sa- livary cortisol and lactate levels during exercise. MSSE Suppl.onset of exercise or improvement in breathing work rates In press.which may be prompted by enhanced airway openings with 13.Trenouth MJ, Timms DJ. Relationship of the functional oro-the use of a mouthpiece. Previous research in the field of pharynx to craniofacial morphology. Angle Orthod. 1999;69mouthpiece use and its effect on human performance sug- (5):419-423.gests that mouthpieces improve performance. However, 14.Kyung SH, Park YC, Pae EK. Obstructive sleep apnea patientsthese studies have been unable to elucidate the possible phys- with the oral appliance experience pharyngeal size and shapeiological mechanisms for this improvement. This research changes in three dimensions. Angle Orthod. 2005;75(1) novel in the area of human movement because it suggests 15.Gale DJ, Sawyer RH, Woodcock A, et al. Do oral appliancesa possible physiological explanation for the improvement in enlarge the airway in patients with obstructive sleep apnea? Aperformance as noted by athletes. Further studies should focus prospective computerized tomographic study. Eur J Orthod.on the reasons for these improvements, noting differences in 2000;22(2):159-168.jaw morphology and airway dynamics for individuals who 16.Gao X, Otsuka R, Ono T, et al. Effect of titrated mandibularmay benefit from a mouthpiece during exercise and sport. advancement and jaw opening on the upper airway in nonap- neic men: a magnetic resonance imaging and cephalometricDISCLOSURE study. Am J Orthod Dentofacial Orthop. 2004;125(2):191-199.Dr. Garner has received an honorarium from Bite Tech Inc. 17.Zhao X, Liu Y, Gao Y. Three-dimensional upper-airway changes associated with various amounts of mandibular advancementREFERENCES in awake apnea patients. Am J Orthod Dentofacial Orthop. 2008;1. Hughston JC. Prevention of dental injuries in sports. Am J Sports 133(5):661-668. Med. 1980;8(2):61-62. 18.Ryan CF, Love LL, Peat D, et al. Mandibular advancement oral2. Glendor U. Aetiology and risk factors related to traumatic den- appliance therapy for obstructive sleep apnoea: effect on awake tal injuries—a review of the literature. Dent Traumatol. 2009; caliber of the velopharynx. Thorax. 1999;54(11):972-977. 25(1):19-31. 19.Green HJ. Neuromuscular aspects of fatigue. Can J Sport Sci.3. ADA Council on Access, Prevention and Interprofessional Re- 1987;12(3):7S-19S. lations; and ADA Council on Scientific Affairs. Using mouth- 20.Westerblad, H, Lee JA, Lännergren J, Allen DG. Cellular mech- guards to reduce the incidence and severity of sports-related oral anisms of fatigue in skeletal muscle. Am J Physiol. 1991;261 injuries. J Am Dent Assoc. 2006;137(12):1712-1720. (2 pt 1): C195-C209.4. Bureau of Dental Education, American Dental Association. Eval- 21.Harms CA, Wetter T, McClaran SR, et al. Effect of respiratory uation of mouth protectors used by high school football players. muscle work on cardiac output and its distribution during max- J Am Dent Assoc. 1964;68:430-442. imal exercise. J Appl Physiol. 1998;85(2):09-618.5. Klossner D, ed. 2008-2009 NCAA Sports Medicine Handbook. 22.Harms CA, Wetter TJ, St Croiz CM, et al. Effect of respiratory 19th ed. Indianapolis, IN: NCAA; 2008:94-95. muscle work on exercise performance. J Appl Physiol. 2000;896. Smith S. Muscular strength correlated to jaw posture and the tem- (1):131-138. poromandibular joint. N Y State Dent J. 1978;44(7):278-285. 23.Kilding AE, Winter EM, Fysh M. Moderate-domain pulmo-7. Smith SD. Adjusting mouthguards kinesiologically in profes- nary oxygen uptake kinetics and endurance running perform- sional football players. N Y State Dent J. 1982;48(5):298-301. ance. J Sports Sci. 2006;24(9):1013-1022.8. Garabee WF. Craniomandibular orthopedics and athletic per- 24.Casaburi R, Storer TW, Ben-Dov I, Wasserman K. Effect of en- formance in the long distance runner: a three year study. Basal durance training on possible determinants of VO2 during heavy Facts. 1981;4(3):77-81. exercise. J Appl Physiol. 1987;62(1):199-207. Compendium—Volume 30 (Special Issue 2) 13
  22. 22. RESEARCH UPDATE Effects of Mouthpiece Use on Auditory and Visual Reaction Time in College Males and Females Dena P. Garner, PhD;1 and Jenni Miskimin, MS2Abstract: Studies in exercise science have suggested that the use of a mouthpiece can improve performance, and theseimprovements may be linked to an enhancement in temporomandibular joint (TMJ) positioning. Studies have suggestedthat by improving TMJ positioning, there is improved blood flow in the area of the TMJ. Changes in TMJ positioning maybe improved with an oral device. The purpose of this study was to determine if there were improvements in auditoryand visual reaction time with the use of a boil and bite mouthpiece. Using a BIOPAC system, study participants (N = 34)were asked to respond to an auditory signal during 40 trials. In the visual reaction time test, participants (N = 13) wereassessed on how quickly they responded to a computer cue for a total of 30 trials. Auditory results showed a significantimprovement with the use of a mouthpiece (241.44 ms) vs without a mouthpiece (249.94 ms). Visual results showed thatparticipants performed slightly better with the mouthpiece (285.55 ms) vs without the mouthpiece (287.55 ms). Thesefindings suggest that the use of mouthpiece positively affects visual and auditory reaction time, which is a vital aspectto optimal sport and exercise performance. Future studies should continue to shed light on possible reasons for theimprovements in auditory and visual reaction time with the use of a mouthpeice. In addition, future studies should furtherilluminate what, if any, connection these improvements have with enhanced TMJ positioning.R eaction time is the period that occurs between a times in people with advanced fencing skills, thereby explain- stimulus and the initiation of muscle response1 ing improved performance.2 and can be assessed as simple reaction time, Many studies in exercise science have suggested that the usechoice reaction time, and discriminate reaction time.1 Sig- of a mouthpiece can improve performance, which may be relat-nals to any sensory system in a variety of populations can ed to an enhancement in temporomandibular joint position-be ascertained in any of the above situations. For exam- ing. Without proper temporomandibular joint positioning,ple, Borysiuk2 evaluated reaction and movement time with nerves and arteries within the joint may become occluded,tactile, acoustic, and visual stimuli in advanced and novice resulting in strain in nearby tissues, thereby reducing bloodfencers. He found that the advanced fencers had a signif- flow.3-7 By neutralizing the temporomandibular joint with aicantly improved reaction time with the visual (P < .057) mouthpiece, patients have reported to their dentists reducedand the tactile (P < .029) stimuli, with no significant differ- pain in the jaw, head, and neck areas, along with increased phys-ences in the acoustic stimuli between novice and advanced ical strength. This improvement in strength may be linked tofencers. However, the mean reaction and movement times improved blood flow and oxygen kinetics associated with re-with all three stimuli were lower in experienced fencers vs the duced stress in the temporomandibular joint, thereby produc-beginners. Borysiuk found fencing training improved reaction ing improved blood flow to the exercising skeletal muscles.8-101Assistant Professor, Department of Health, Exercise and Sport Science, The Citadel, Charleston, South Carolina2ACSM Health and Fitness Specialist, Boeing Activity Center, The Boeing Company, Everett, Washington14 Compendium—Volume 30 (Special Issue 2)