***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Mouthguards are considered by most authorities to be an essential part of equipment for players participating in body-contact sports .  Mouthguards provide excellent dental protection but not all players use them , complaining of breathing difficulties and problems with speaking . Although information exists concerning dental trauma and mouth protector use , there are no reported data that quantify the physiological effects of wearing mouthguards . The purpose of this study was to measure the ventilatory and gas exchange effects of wearing a mouthguard . Ten healthy men and seven women aged 20 - 36 years ( mean(s.d . ) 27.2(5.2 ) years ) were used as subjects .  Forced expiratory air volume at 1 s ( FEV1 ) and peak expiratory flow rates ( PEF ) were measured on each subject while wearing either no mouthguard or one of three different over-the-counter mouthguards including one maxillary ( mouthguard 1 ) and two different bimaxillary guards ( mouthguards 2 and 3 ) . To determine the effects of wearing each of the mouthguards during exercise , oxygen consumption ( VO2 ) was measured while exercising on a cycle ergometer for 5 min at a light and heavy workload . An ANOVA of repeated measures was used to determine statistical differences . In each case , the wearing of a mouthguard significantly ( P less than 0.05 ) reduced FEV1 and PEF in comparison with no mouthguard . FEV1 was reduced 8 % with mouthguard 1 , and 12 % and 14 % with mouthguards 2 and 3 respectively . PEF was reduced by 7 , 15 and 15.8 % with mouthguards 1 , 2 and 3 respectively . The wearing of the different mouthguards did not significantly change VO2 while exercising at the lower work level whereas VO2 was significantly ( P < 0.05 ) reduced at the heavier workload . This surprising reduction in VO2 during heavy exercise may be due to a ' pursed-lip ' type of breathing which has been shown to decrease CO2 tension , increase oxygenation and exercise tolerance . It can be concluded that although mouthguards may be perceptably uncomfortable and restrict forced expiratory air flow , they appear to be beneficial in prolonging exercise by improving ventilation and economy BACKGROUND The authors conducted a study to assess the effects of custom-fitted mouthpieces on gas exchange parameters , including volume of oxygen consumption over time [ corrected ] ( VO(2 ) ) , volume of oxygen consumption over time per kilogram of body weight [ corrected ] ( VO(2 ) /kg ) and volume of carbon dioxide production over time [ corrected ] ( VO(2 ) ) . METHODS Sixteen physically fit college students aged 18 through 21 years performed two 10-minute treadmill runs ( 6.5 miles per hour , 0 percent grade ) for each of three treatment conditions ( mouthpiece , no mouthpiece and nose breathing ) . The authors assigned the conditions r and omly for each participant and for each session . They assessed gas exchange parameters by using a metabolic measurement system . RESULTS The authors used analysis of variance to compare all variables . They set the significance level at α = .05 and used a Tukey post hoc analysis of treatment means to identify differences between groups . The results showed significant improvements ( P < .05 ) in VO(2 , ) VO(2 ) /kg and VCO(2 ) in the mouthpiece condition . CONCLUSIONS The study findings show that use of a custom-fitted mouthpiece result ed in improved specific gas exchange parameters . The authors are pursuing further studies to explain the mechanisms involved in the improved endurance performance exhibited with mouthpiece use . CLINICAL IMPLICATION S Dental care professionals have an obligation to underst and the increasing research evidence in support of mouthpiece use during exercise and athletic activity and to educate their patients OBJECTIVES This study compared the comfort of two bimaxillary custom-fitted mouthguards . One type was made with silicone rubber and the other with methyl-methacrylate ( acrylic ) . METHODS The study was a within-subject crossover clinical trial with 52 high-school rugby players who were r and omly allocated to one of two groups . The first group wore a silicone mouthguard for 4 months and an acrylic one for the following 4-month period . The second group wore an acrylic mouthguard followed by a silicone one for similar periods . Comfort , bulkiness , stability , hardness , ability to talk and to breathe , oral dryness , nausea and inclination to chew were evaluated for each period using a Visual Analogue Scale question naire . RESULTS There was no significant difference concerning comfort , bulkiness , ability to talk and to breathe , oral dryness and nausea between silicone and acrylic mouthguards by group and time of examination ( Three-way ANOVA P>0.05 ) . Acrylic mouthguards were more stable and harder than silicone ones ( Wilcoxon 's test P<0.01 ) . Tendency to chew was greater for silicone appliances ( P<0.01 ) . For stability , hardness and inclination to chew , there was no significant difference in the response of the players based on the sequence of use of the two types of mouthguard during the survey ( Mann-Whitney test P>0.05 ) . At the end of the study , 56 % of the players preferred to keep the acrylic mouthguard and 44 % chose the silicone one . This choice did not vary between the groups ( chi2 , P>0.05 ) . CONCLUSION Silicone rubber mouthguards were well accepted by the players but technical improvements in silicone material s are needed to improve hardness and stability of silicone mouthguards for sport Protective mouthpieces have been used in a variety of sports to decrease the risk of orofacial injury . There are limited data to suggest that mouthpiece use during exercise may also provide an ergogenic effect . The aim of the present study was to investigate the effects of 3 different mouthpiece design s-boil- and -bite ( BB ) mouthpiece , ethylene vinyl acetate ( EVA ) custom m and ibular mouthpiece , and polypropylene ( Poly ) custom m and ibular mouthpiece-on respiratory physiology parameters and compare them with results of a no-mouthpiece ( NM ) condition . Sixteen college-aged , recreationally fit subjects ran for 10 minutes in 4 separate trials ; mouthpiece conditions were r and omly assigned to each trial for all subjects . Respiratory and cardiorespiratory measures , including oxygen uptake , carbon dioxide exhalation , ventilation , heart rate , tidal volume , and respiratory rate ( RR ) , were assessed throughout testing . A repeated- measures analysis of variance indicated that RR was significantly lower ( P = 0.04 ) in the BB mouthpiece condition ( 27.92 breaths per minute [ BPM ] ) than in the NM condition ( 30.63 BPM ) . In paired t tests between conditions , the RR demonstrated in the BB condition ( 27.92 BPM ) was significantly lower ( P = 0.04 ) than that of each other condition ( NM , 30.63 BPM ; EVA , 29.92 BPM ; and Poly , 29.92 BPM ) . The outcomes of the present study demonstrate that the use of the BB mouthpiece decreased RR during exercise . The differences cited between conditions may be attributed to the design of the mouthpiece and its m and ibular placement as well as the activity of the genioglossus muscle . However , future studies should assess these parameters to determine the plausibility of these theories BACKGROUND Prevention of traumatic dental injuries relies on the identification of etiologic factors and the use of protective devices during contact sports . Mouthguards are considered to be an effective and cost-efficient device aim ed at buffering the impacts or blows that might otherwise cause moderate to severe dental and maxillofacial injuries . Interestingly , besides their role in preventing injury , some authors cl aim that mouthguards can enhance athletic performance . Thus , the purpose of this controlled r and omized trial was to evaluate and compare the effect of two different types of mouthguards on the athletic performance and strength of collegiate athletes . MATERIAL S AND METHODS Eighteen college athletes ranging from 19 to 23 years participated in this study . Devices tested in this study included an over-the-counter boil- and -bite mouthguard ( O-Flow ™ Max Under Armour ® ) ( UA ) and a custom-made mouthguard ( CM ) . Physical tests were carefully selected by the head athletic trainer and aim ed at evaluating the strength and performance . The following sequence was carried out on each test day : ( i ) 3-stroke maximum power ergometer test , ( ii ) 1-min ergometer test , and ( iii ) a 1600-m run . A r and om assignment was developed to test all three experimental groups on each test day . Following the tests , each athlete completed a brief anonymous survey aim ed at evaluating the athletes ' overall satisfaction with each type of mouthguard . RESULTS Custom-made mouthguards  had no detrimental effect on athletic strength and performance and were reported by the athletes as being comfortable and not causing difficulty in breathing . In contrast , boil- and -bite mouthguards did not perform as well and were reported as being uncomfortable and causing breathing difficulties . CONCLUSIONS Based on the results of this study , the use of custom-made mouthguards should be encouraged in contact sports as a protective measure , without concern for any negative effect on the athletic performance of the athletes The latest findings on the ergogenic effects of a dentistry- design , bite-aligning mouthpiece require additional research to assess its impact on anaerobic ability and ventilatory parameters . This paper was aim ed at determining the ergogenic acute effects of wearing a custom-made mouthpiece on oral airflow dynamics , 30-s Wingate Anaerobic Test performance parameters . Twenty-eight healthy and physically-active male subjects ( age : 24.50 ± 3.32 , height : 181.34 ± 7.4 , weight : 78.14 ± 8.21 ) , were voluntarily studied . The subjects were first briefed on the test protocol s , and then performed the 30s Wingate test and Spirometer test . The experimental trials were performed in a r and om counterbalanced order . We evaluate maximum expiratory volume ( VEmax L min(-1 ) ) , mean power ( W kg(-1 ) ) , peak power ( W kg(-1 ) ) , time to peak ( s ) , rate to fatigue ( Ws(-1 ) ) and lactate production ( mMol L(-1 ) ) , rate of perceived exertion ( RPE ) . There were significant differences between mouthguard and no-mouthguard conditions in mean power ( W kg(-1 ) ) , peak power ( W kg(-1 ) ) , time to peak ( s ) , and rate to fatigue ( Ws(-1 ) ) for the 30-s Wingate Anaerobic Test . Significantly lower lactate production ( mMol L(-1 ) ) was observed , in mouthguard condition but no significant differences were found in RPE . In airflow dynamics , the VEmax L min(-1 ) was significantly higher when comparing the mouthguard and the no mouthguard conditions in both forced and unforced conditions . In conclusion , wearing a customized mouthguard  improves anaerobic ability and increases forced expiratory volume . This study will help practitioners improve athlete 's performance in anaerobic activities where high intensity action might provoke jaw-clenching , contributing in reductions of lactate and fatigue , and improving ventilatory parameters Abstract Dunn-Lewis , C , Luk , H-Y , Comstock , BA , Szivak , TK , Hooper , DR , Kupchak , BR , Watts , AM , Putney , BJ , Hydren , JR , Volek , JS , Denegar , CR , and Kraemer , WJ . The effects of a customized over-the-counter mouth guard on neuromuscular force and power production in trained men and women . J Strength Cond Res 26(4 ) : 1085–1093 , 2012—Although mouth guards were originally design ed for injury prevention , even elite athletes are now using performance mouth guards to improve athletic success . Both expensive custom models and over-the-counter models are available , but the efficacy is not well known . Some athletes remain wary of the perceived potential for detriments using a mouth guard to their performance . Thus , the purpose of this study was to examine various physical performance tests when using a mouth guard including a customized over-the-counter mouth guard .  Twenty-six trained men ( 25 ± 4 years ; 1.78 ± 0.07 m ; 83.3 ± 11.4 kg ) and 24 trained women ( 23 ± 3 years ; 1.65 ± 0.08 m ; 62.6 ± 7.8 kg ) volunteered for the investigation . The subjects completed a familiarization period and then balanced and r and omized treatment conditions that included : ( a ) a customized Power Balance performance mouth guard ( PB MG ) ; ( b ) a regular over the counter boil- and -bite mouth guard ( Reg MG ) ; and ( c ) a no mouth guard ( No MG ) treatment condition . At each visit , the subjects completed a testing protocol that was sequenced in the following order : sit- and -reach flexibility , medial-lateral balance , visual reaction time , vertical jump , 10-m sprint , bench throw , and plyo press power quotient ( 3PQ ) . Heart rate and rating of perceived exertion ( RPE ) were recorded around the 3PQ . Significance was set at p ⩽ 0.05 . Expected significant sex differences existed for all power , strength , and speed variables . Bench throw power ( watts ) and force ( newtons ) were significantly higher under PB MG than either Reg MG or No MG or in both men and women . The 3PQ power and force production were higher than that for the other 2 treatments for the PB MG for men only . There were no significant differences for treatment conditions in the heart rate or RPE after the 3PQ test . Men were better able to maintain significantly higher 3PQ power production under PB MG treatment condition compared with the 
    Output:
    
When the results were analyzed separately for each subgroup ( type of MG and place of use ) , the meta- analysis showed that the effect of the use of an MG on VO2 max and VE max was not significant when custom-made MGs were used .
The use of an MG overall decreased VO2 max and VE max compared to the control .
Nevertheless , custom-made MGs seem to have no effect on these parameters