The effects of a custom-fitted mouthguard on isometric cervical muscle strength

Overview

The study will include young adults aged 18-35 years that fit the ACSM guidelines of an active individual. Pregnant persons, self-reported history of spinal cord injury, current neck pain, TMJ, chronic pathologies affecting the head/neck, and self-reported concussion or neck injury in the pack 6 months will be excluded. Potential subjects will be recruited through flyers posted on campus, online, or through kinesiology classes. Interested subjects will contact study personnel to schedule an appointment for consent and screening. After consent, subjects will be screened to ensure they meet all inclusion and exclusion criteria. Once eligibility is determined, enrolled subjects will be fitted for the custom mouthguards and undergo data collection. Visits: Enrolled subjects will be asked to complete two study visits. The first visit will be completed immediately after consent and enrollment. The second visit will be completed between 1-2 weeks after the first visit, depending on scheduling availability. The first visit will consist of consent, enrollment, fitting for the custom mouthguard, and familiarization with the testing procedures. Subject height, weight, neck length, neck circumference, and head circumference will also be recorded. The second visit will be identical to the first, but the mouthguard fitting and anthropometric measurements will not need to be repeated.

Participants’ neck flexion, extension, and lateral flexion maximal isometric strength will be assessed using an in-line tension high sensitivity load cell anchored to the floor and connected to a harness around their head. Neck rotation will be assessed using a handheld dynamometer. Participants will perform 3 submaximal trials for each position as a warm-up. Participants will then be instructed to perform 3 trials of each movement with the cue “pull as hard and fast as you can for 5 seconds at 100%.” To mitigate fatigue, they will be given 30 seconds of rest between trials, 3 minute of rest between positions, and 5 minutes of rest between conditions. The head harness will be positioned across the occiput for extension, the temporal bones for lateral flexion, and the forehead for flexion. The participants will be positioned prone on a padded table for extension, side-lying for lateral flexion, and supine for flexion. The participants torso and shoulders will be secured with seat belts to prevent additional contributions from those structures. For rotation, subjects will be seated next to a wall with a handheld dynamometer positioned between their temporal bone and the wall. They will be instructed to “push as hard and fast as you can for 5 seconds at 100%.” The rest protocols will also be 30 seconds between trials and 1 minute between positions. Measures from each mouthguard will be standardized across trials and conditions.