Potential effects of wearing custom-made mouthguards on post-deadlift autonomic activity

• Published in: Journal of The Showa University Society Vol. 81; no. 5; pp. 453 - 458
• Main Authors: Uema, Yuji, Sambe, Takeyuki, Ochiai, Hirotaka, Kogo, Mari, Hachisu, Mitsugu, Ohbayashi, Masayuki, Funato, Masahiko, Haga, Shugo
• Format: Journal Article
• Language: Japanese
• Published: The Showa University Society 2021; 昭和大学学士会
• Subjects: autonomic nerve activity; custom-made mouthguard; deadlift; fatigue; カスタムメイドマウスガード; デッドリフト; 疲労; 自律神経活動
• ISSN: 2187-719X; 2188-529X
• DOI: 10.14930/jshowaunivsoc.81.453

Deadlifting strongly influences autonomic response, as this intensive strength-training activity taxes the body through a progression of lifting heavy weights across three separate attempts. We sought to study this autonomic response after deadlifting, and the potential effect of wearing a mouthguard during deadlifting. Ten healthy male volunteers aged 30.0±15.0 years were recruited. The deadlifting weight for each study subject was selected based on 90％ of the individual’s maximum weight （90％max; 153.3±31.4kg）. The electrocardiographic R-R interval variabilities （CVRRs） were analyzed using the Kiritsu Meijin （Crosswell Co., Yokohama, Japan） autonomic nerve activity analysis software by measuring electrocardiogram activity. We measured the subjects’ CVRRs while sitting for 2min, immediately upon standing, and after standing for 1min immediately after deadlifting. We monitored the five autonomic parameters at three different weights of 90％max±5kg and then the effect of wearing custom-made mouthguards （CMGs） at 2mm and 4mm thickness with 90％max weight. Individualized CMGs were fabricated by a thermoforming device using an ethyl vinyl acetate sheet. Statistical analysis was performed using analysis of variance, and multiple comparisons of the Bonferroni correction were employed. Changes in heart rate （ΔHR） by deadlifting with 90％max±5kg increased alongside the increasing weight, and we found that ΔHR with 90％max＋5kg was significantly increased （p＝0.039） compared to that with 90％max −5kg. Wearing a 4mm CMG resulted in marginally significantly higher （p＝0.072） ccvHF values than without CMG. The ccvHF value is an index of parasympathetic activity, and a higher value is considered to be related to physical resilience; therefore, wearing a 4mm CMG may reduce fatigue in individuals in deadlifting and similarly intensive exercise.