Effects of Concurrent Activiation Potentation Induced by Customized Mouth Guard on Baseball and Softball Performance
Phase: NA
Conditions: Oral Manifestations, Control Condition
Sponsor: National Taiwan Sport University

Effects of concurrent activiation potentation induced by customized 
mouth guard on baseball and softball performance 
 
Document Date: Feb 16, 2025 
IRB approved date: Dec 20, 2023 
 
 
Project summary 
This study recruited 45 baseball and softball players, including 30 fielders and 15 
pitchers. Using a randomized crossover experimental design, the study was divided into 
randomised divided into customised mouthguards trial (MG) and control trial (CON) 
without temporal positioning. After the participants wore the mouthguard, they 
performed the vertical jump and grip strength tests sequentially. At the end of the test, 
depending on the pitcher or fielder, a baseball pitching ability test or a hitting ability 
test was conducted using a radar baseball tracking system. It is expected to analyze the 
vertical jump height, grip strength, pitchers' straight and changeup ball speeds, rotation 
speeds, degree of displacement, on-base and off-base locations. Hitting ability was 
expected to be documented with respect to initial velocity, elevation, and consistency 
of elevation. 
 
Key word: concurrent activation potentiation, athletic performance, bite force 
 
 
 
 
 

Introduction 
Concurrent Activation Potentiation (CAP) is a strategy that synchronizes voluntary 
contraction of remote and target muscles through remote voluntary contraction (RVC), 
resulting in an increase in contractile capacity of the target muscles, which in turn 
facilitates exercise performance (1). Possible physiological mechanisms contributing to 
CAP include increased alpha motor neuron activity, stimulation of myoclonic changes, 
motor cortical overflow theory, and inhibition of presynaptic inhibition. The most 
widely recognised theories are motor cortical overflow and inhibition of presynaptic 
inhibition (2). CAP can be achieved by using either single or multiple RVC muscle 
groups. The most commonly used muscle group is jaw clenching. The activation of the 
motor cortex area responsible for controlling the musculature of the jaw is known to 
trigger the activation or strengthening of the motor cortex area of the arms and legs, 
consequently leading to enhanced muscle contraction in these extremities (2).  
 
Recent studies have indicated that the utilization of customized mouthguards may serve 
as an effective strategy to enhance the contraction of temporomandibular joint muscles, 
thereby improving the CAP effect (3). The use of customised mouthguards improves 
the CAP effect and enhances maximum isometric grip strength (4, 5), the force and 
height of vertical jump (4, 6-8), increases explosive power, muscle strength (3) and 
improves sprinting ability over short distances (8). It appears that the use of customised 
mouthguards may have an effect on improving the performance indexes of the 
explosive type of sports. However, there was no study that have examined the effects 
of using customised mouthguards on the performance of baseball pitcher. 
 
For baseball pitchers, the fastball velocity and the sharpness of breaking ball are 
important indicators of pitching performance. For indicators of muscular strength and 
physical performance, excellent pitchers (e.g., MLB) generally have better indicators 
of these pitches, as well as better lower extremity explosive strength and upper 
extremity strength (9). However, the extent to which increasing the bite force through 
customized mouthguards can enhance the muscle strength and athletic performance of 
baseball pitchers remains to be investigated. The purpose of this study is to investigate 
whether the use of customised mouthguards is effective in improving the athletic 
performance of baseball and softball performance. 
 
Methods 
Study design 
This study used a randomised crossover experimental design in which participants were 
randomised to complete a customised mouthguards trial (MG) and a control trial (CON) 

without mouthguards. Participants were tested for grip strength, counter movement 
jump, and baseball pitching ability with (MG) or without mouthguards (CON). During 
the study, the participants maintained a training schedule of 6 days and 1 day of rest. 
The study was conducted on the next day after the seventh day off to avoid training or 
fatigue factors affecting the accuracy of the experiment. 
 
Participants 
25 professional baseball and softball players were recruited for this study. The inclusion 
criteria for this study were: (i) has won the top 8 national level baseball of softball 
championships in the last three years. (ii) no cardiovascular and joint diseases. (iii) aged 
20 or above who are adults. (iv) continuing to train professionally more than 5 days a 
week for the past year. The exclusion criteria for this study were: (i) have not won the 
top 8 national baseball or softball championships in the past three years. (ii) have a 
cardiovascular or joint disease, or any injuries that may be impaired by exercise. (iii) 
participants who are underage or not in regular baseball or softball training. (iv) have 
injury to the temporomandibular joint. Prior to involvement in the study, participants 
are provided with a participant consent form to sign after receiving comprehensive 
information regarding the study and its potential risks. This study received approval 
from the Institutional Review Board of Jen-Ai Hospital - Dali Branch (202300083B0). 
All experiments were carried out in a covered playground stadium. This study was 
conducted following the Declaration of Helsinki. 
 
Protocol 
Approximately one month prior to the commencement of the experiment, participants 
were referred to a dentist for a dental diagnosis. A customized mouthguard was 
subsequently fabricated. All participants were required to perform the same test at least 
2 times before the formal test to familiarize themselves with the content of the formal 
test. Participants were examined by a dental professional to check the alignment of the 
teeth, obtain the distribution of occlusal forces using a special occlusal plate, and make 
dental molds. After the customized mouthguards are completed, the test begins. 
 
All tests began at 3:00 p.m., which is the baseball team's daily practice time. 
Participants recorded the first warm-up, including all dynamic stretches, sprints, and 
number of pitches, and performed the same warm-up in the next experiment. After a 
personalized warm-up, participants were randomly fitted with customized mouthguards 
(MG trial) or without mouthguards (CON trial), and tested for bite force, grip strength, 
counter movement jump and pitching test in sequence.  
 

Outcome measure 
Bite force was measured using a pressure-sensitive occlusion plate (GC Dental Prescale 
II) and subsequently scanned with a Bite Force Analyzer. Prior to the experimental 
phase, the subjects were familiarized with the protocol by first handling the plastic 
wrapping within the bag of the bite plate. They were then instructed to bite down with 
maximum force for a duration of ten seconds, thereby replicating the instructed scenario. 
The operator then selected the appropriate bite plate size (S, M, or L) and positioned it 
within the subject's oral cavity, replicating the initial procedure. The scanning process 
was conducted within approximately ten minutes with the bite plates stored in their 
original packaging to prevent light exposure during preparation and scanning. GC 
Prescale II bite plates were maintained in environments with controlled light and 
temperature (5°C) to ensure material stability. 
 
In the grip strength test, the participant should stand with their feet separated to the 
width of their shoulders, their hands in a natural and unstretched position, and the grip 
strength meter (Smedlay's Hand Grip Dynamometer TTM, Japan) (10) held at the 
second knuckle. The researchers verbally reminded the participants to clench their jaws 
with all their strength while gripping the grip strength meter with all their strength. 
Participants were then performed two maximal grip strength tests with the dominant 
hand and the non-dominant hand, with a 1-minute break in between each test. The value 
is presented as the average of two sums of hands. 
 
Jump height of counter movement jump was measured in this study using the 
SmartJump contact mat (Smartjump, Fusion Sport, Sumner Park, Queensland, Australia) 
measurement monitoring system (11). The participant assumes a standing posture on a 
mat with arms crossed, and is verbally prompted to clench their jaws and propel 
themselves upward with maximal force while simultaneously descending until their 
thighs are in a parallel position with the ground. Vertical jumps were performed three 
times, each time with a one-minute rest, and the average value of the three times was 
analyzed. 
 
In this study, pitching ability was analyzed using Rapsodo pitching 2.0 (Rapsodo 
Baseball System, Rapsodo Inc, Fishers, IN) (12). After a full warm-up, participants 
were given a pitching test of 10 fastballs and 5 sliders. According to statistics data from 
Statcast Search website (https://baseballsavant.mlb.com/statcast_search), major league 
pitchers throw about 15 pitches per inning, including 61% fastballs and 39% breaking 
ball. Based on this data, the pitcher was asked to throw 15 pitches, including 10 fastballs 
and 5 sliders, with 15 seconds of rest between each pitch. Recorded ball speeds and 

spin rates of fastballs and sliders for subsequent analysis. 
 
Fabriction of mouthguards for participants 
The customized mouthguard in this study was made by a professionally trained dentist. 
The impressions were made with alginate (GC Aroma Fine Plus Normal Set Alginate), 
following the manufacturer's guidelines to the best of our ability. The pouring was 
executed immediately after the impression was made with dental stone (GC Fujirock 
EP Type 4 Dental Stone) in accordance with the manufacturer's instructions and using 
a dental laboratory vibrator. The vibrator was utilized to eliminate air pockets within 
the dental stone, as these pockets have the potential to induce imperfections in the cast 
model.  
 
The customized mouthguard was vacuum formed using a dental stone model as a mold. 
A thermoformed mouthguard material, copolyester (Keystone Pro-Form vacuum 
forming materials, 0.5 mm), was utilized to overlay the dental stone. The fabrication of 
MG in maximum intercuspation involves the utilization of a dental stone cast derived 
from alginate, which is subsequently overlaid on top of the thermoformed material 
following a heating process (Figure 1). 
 
Statistical Analysis 
All data are presented as means ± standard deviations. The Shapiro–Wilk test was 
employed to evaluate the normality of the data distribution. The bite force, grip strength, 
counter movement jump and pitching test were employed to analyses the through paired 
t-tests. Effect sizes were calculated using Cohen's d to quantify the magnitude of 
observed effects and defined as trivial (<0.20), small (0.20–0.40), moderate (0.40–0.80), 
and large (>0.8), respectively. The power value of each data was conducted using 
G*Power 3.1.9.6 software (13). All data were calculated using SPSS (version 20, 
Chicago, IL, USA), and the significance level was p < 0.05. 
 
 
 

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