Abstract
Purpose: The purpose of this study was to investigate the effects of a self-adapted, jaw repositioning mouthpiece and jaw clenching on muscle activity during the countermovement vertical jump (CMVJ) and isometric mid-thigh clean pull (MTCP). Methods: Thirty-six healthy, recreationally trained males (n=36; age, 23 ± 2.8 years; height, 178.54 ± 9.0 cm; body mass, 83.09 ± 7.8 kg) completed maximal CMVJ and MTCP assessments under six experimental conditions: jaw repositioning mouthpiece plus clenching (MP+C), jaw repositioning mouthpiece with jaw relaxed (MP), traditional mouthguard plus clenching (MG+C), traditional mouthguard with jaw relaxed (MG), no mouthpiece plus clenching (NoMP+C) and no mouthpiece with jaw relaxed (NoMP) while muscle activity of the dominant leg medial gastrocnemius (G), medial hamstring (H), vastus medialis (VMO), and erector spinae (ES) was recorded. Results: Repeated measures ANOVA revealed no changes in MTCP muscle activation for any mouthpiece or clench condition. Jaw clenching, regardless of mouthpiece condition, significantly improved prime mover muscle activation during CMVJ ( p < .001). Prime mover muscle activation was significantly greater during CMVJ assessment for jaw repositioning mouthpiece and no mouthpiece conditions over the use of a traditional mouthguard ( p < .001), but the repositioning mouthpiece did not lead to improved muscle activation compared to no mouthpiece ( p > .05). Conclusion: These findings support jaw clenching as a viable technique to elicit concurrent activation potentiation (CAP) of prime mover muscle activity during dynamic but not isometric physical activity. Keywords: jaw repositioning mouthpiece, jaw clenching, concurrent activation potentiation, muscle activation
Highlights
The use of jaw-aligning mouthpieces to alleviate the symptoms associated with temporomandibular joint disorder (TMD) is quite common and has been purported to improve various aspects of performance (Smith, 1978; Kaufman, 1980; Kaufman and Kaufman, 1984)
This study examined how jaw clenching and jaw alignment via a self-adapted, jaw repositioning mouthpiece impacted muscle activation during maximum countermovement vertical jump (CMVJ) and maximum isometric mid-thigh clean pull (MTCP) assessments
Further analysis revealed that the peak gastrocnemius EMG signal was significantly greater for the mouthguard plus clenching (MG+C) compared to mouthguard with jaw relaxed (MG) condition, and peak erector EMG signal was significantly greater for the no mouthpiece with jaw relaxed (NoMP) compared to the no mouthpiece plus clenching (NoMP+C) condition
Summary
The use of jaw-aligning mouthpieces to alleviate the symptoms associated with temporomandibular joint disorder (TMD) is quite common and has been purported to improve various aspects of performance (Smith, 1978; Kaufman, 1980; Kaufman and Kaufman, 1984). Dental impressions taken by a dental practitioner are used to custom fit the jaw repositioning devices to the individual, which leads to an expensive end product; there are self-adaptable boil-and-bite versions available These products can be designed to fit the upper or lower jaw, depending on the specific oral appliance model and individual preference, and have small acrylic bite plates that inhibit direct contact of the upper and lower molar teeth when the mouth is closed. This changes the temporomandibular joint relationship, pulling the mandible down and slightly forward, which mimics the jaw position achieved with the TMD treatment devices
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