New
research proves XLR8 increases isometric strength by up to
50%!
Isometric
Strength of Deltoid and Cervical Flexor Muscles under Relaxed
Open, Habitual Bite and a Raised Bite (XLR8™)
By
Albert G. Forgione, PH.D.
Introduction
Research at this laboratory has shown that increasing the vertical dimension
in a stepwise fashion increases isometric strength of both cervical flexors
and deltoid muscles. This tendency has also been found with abdominal muscles
and leg muscles. The present study was designed to compare isometric strength
resulting from the wearing of a sports mouth guard (XLR8) fitted by the
subjects according to the instructions provided by the manufacturer. Isometric
strength was also measured with the mandible in a relaxed open position
and biting in habitual occlusion. The research question is can sports guards
be placed by non dentally trained individuals to result in peak strength.
Conclusion
The highest strength levels for both cervical flexors and deltoids occurred
biting the XLR8 guard, approximately 50% greater than biting in
habitual. The weakest condition measured was biting in
habitual. One can safely say that the greater the strength of cervical
and deltoids,
the less the likelihood of injury in the neck and shoulder. Without the
mouth guard, an anticipated hit or actual contact will result in a weaker
performance. Another and sartorius muscles respond similarly. Observations
from other laboratories in Japan and Korea have found similar results.
Size
of the effect
Biting the XLR8 produced an increase in isometric strength of 2.39 kg for the
right deltoids, 2.01 kg for the left deltoids and 2.16 kg for the cervical
flexors from the levels produced in the biting WO condition. This is 58%, 44%
and 51% respectively.
Materials
and Method
Twenty subjects (13 female and 7 male) with a mean age of 27.2 years were given
a sports guard (XLR8) and instructed to fit the guards according to the manufacturer's
instructions. On the test day, deltoid and cervical muscles were tested using
a force transducer (kilograms).
- All
subjects were first tested in the relaxed open position for
cervical and deltoid muscles right and left.
- All
subjects were then tested while biting in habitual occlusion.
- The
XLR8 was then inserted for the third set of measurements.
- One
experimenter recorded peak strength while the second experimenter
tested strength (single blind).
Detailed
Results
A two-way (AS) ANOVA was performed with subjects as
their own controls. A main effect was obtained of F=22.6 p<0.00001
(see Table I). Shown in Table I are Post Hoc Comparisons of all
possible pairs of means.
1.
|
mo1
|
mandible
relaxed open
|
deltoidR
|
2.
|
mo2
|
mandible
relaxed open
|
deltoidL
|
3.
|
mo3
|
mandible
relaxed open
|
cervical
|
4.
|
bite1
|
biting
without guard
|
deltoidR
|
5.
|
bite2
|
biting
without guard
|
deltoidL
|
6.
|
bite3
|
biting
without guard
|
cervical
|
7.
|
plate1
|
biting
on XLR8
|
deltoidR
|
8.
|
plate2
|
biting
on XLR8
|
deltoidL
|
9.
|
plate3
|
biting
on XLR8
|
cervical
|
Figure
1 shows that the means of right and left deltoids with relaxed
open bite were essentially equal. The chart for Analysis of
Variance (mo1 vs mo2) supported what was apparent. Comparing
relaxed open vs. biting (mo1 vs bite1) there was a significant reduction in
strength when biting for the right deltoid but not for the left.
When biting the XLR8, however, strength increased significantly
for both right and left deltoids. The strength levels attained
wearing XLR8 were greater than relaxed open and habitual bite
for both right and left deltoids.
Figure
1: Mean right and left Deltoid Isometric Strength with "Relaxed" Open,
Biting in Habitual Occlusion (WO) and Biting on XLR8 Mouthguard.
20 Subjects' Force Measured in Kilograms.
Figure
2 shows the strength of the cervical flexors under the three
bite conditions. The mean for the relaxed open bite (mo3) is
greater than the mean for biting in habitual occlusion (bite3)
which means that strength was reduced when subjects bit
in habitual occlusion.
As
with the Deltoids, when subjects bit on XLR8 the mean strength
was significantly greater than relaxed open and habitual bite
conditions. Overall, the habitual bite condition was associated
with the weakest scores, significantly less than the relaxed
open condition. The XLR8 condition bite without (habitual) conditions.
Figure
2: Mean Cervical Flexor Isometric Strength with bite Relaxed Open,
Biting in Habitual Occlusion (WO) and biting on XLR8 Mouthguard.
20 Subjects/ force Measured in Kilograms.
