Mouthpiece use during heavy resistance exercise affects serum cortisol and lactate

Abstract

Recent reports suggest the use of mouthpieces may be beneficial at improving aerobic and anaerobic exercise performance. However, the mechanisms of these reported improvements have yet to be elucidated. The purpose of this study was to explore the possible mechanisms of improved performance using the ArmourBite® mouthpiece. Using a within subject randomized treatment design, 15 experienced resistance trained males (19–26 years of age) performed 6 sets of 10 repetitions of free weight back squats at 80% of 1RM with and without a mouthpiece. Blood samples were collected before exercise, after 3 sets (Mid), immediately post (Post), 30 min post (Post-30), 60 min post (Post-60) and 120 min post (Post-120) exercise. Samples were analyzed for lactate and ELISA was used to determine cortisol. Mouthpiece use resulted in more repetitions completed without assistance (54.36 ± 0.61 vs. 53.27 ± 0.79, p = 0.046) and fewer assisted repetitions (6.73 ± 0.79 vs. 5.64 ± 0.61 repetitions, p = 0.046) compared to the control group. Lactate concentrations were lower in the treatment vs. control group at the Post (11.54 ± 2.23 vs. 13.07 ± 2.96 mmol/L, p = 0.023) Post- 30 (4.45 ± 1.94 vs. 5.41 ± 1.90 mmol/L, p = 0.021), and Post-60 (2.07 ± 0.94 vs. 2.55 ± 0.96 mmol/L, p = 0.048) sampling periods. Mouthpiece use lowered cortisol levels at Mid and Post-30 (19.39 ± 6.90 vs. 27.84 ± 14.56 μg/dL, p = 0.02 (22.91 ± 8.47 vs. 31.81 ± 10.79 μg/dL, p = 0.04). Cortisol AUC values showed significant differences within the AUC Pre-Post control and treatment (55.16 ± 23.84 vs. 41.95 ± 2.65 μg/dL, p = 0.02) groups. These data suggest that mouthpiece use may increase performance and decrease stress when used during intense resistance exercise.

Keywords:

• performance mouth guard
• jaw clenching
• anaerobic exercise
• physiological parameters
• lactate
• cortisol

Public Interest Statement

Mouthguards/mouthpieces have traditionally been used for protection during collision sports. However, our research finds that mouthpieces may also provide a performance benefit to the user during strenuous exercise. This article finds that individuals who used a lower custom-fitted mouthpiece experienced improvements during intensive resistance exercise. More specifically, with mouthpiece use, their blood lactate levels were 13% lower immediately after exercise and they had a 39% reduction in cortisol levels 30 minutes post exercise. What does this mean? For those who take part in strenuous anaerobic exercise, this improvement in both lactate and cortisol could benefit recovery mechanisms which would then improve subsequent training sessions. Thus, it is evident from this study that wearing a mouthpiece promoted positive physiological changes. More exploration into why this occurred is needed in order to understand the effect of mouthpiece use during exercise.

Competing Interests

The authors declare no competing interest.

Acknowledgements

The authors would like to thank The Citadel Foundation and Bite Tech, Inc. for partial funding of this research.

Additional information

Notes on contributors

W.D. Dudgeon

W.D. Dudgeon received a PhD in exercise science with a focus on applied physiology at the University of South Carolina in 2006. He is currently a tenured, associate professor at the College of Charleston and the head of department of health and human performance. His research interests include mouthpiece use during exercise and sport nutrition.

The Human Performance Laboratory at The Citadel has spent the last 13 years assessing the effect of mouthpiece use on human performance parameters during exercise. Parameters assessed have included oropharyngeal width and diameter, cortisol (blood and salivary), lactate levels, respiratory changes and human work output. The research in our laboratory has suggested a physiological effect during both aerobic and anaerobic performance. Theories which support these changes may include increased cerebral blood flow that occurs during clenching on a mouthpiece and improved placement of the genioglossus which reduces the respiratory rate during aerobic exercise. The latest research presented in this paper demonstrates blood marker changes in both lactate and cortisol after a bout of intense resistance exercise. Future research needs must assess the causes for these physiological changed with mouthpiece use during exercise