External Bilateral Heating of the Carotid Arteries in Cold Weather
Environments and its effect on Dexterity, Reaction Time, Gross Motor
Strength, and Comfort Levels.
By: Noah Budi, Dr. Tom Wetter
Key Words: cold weather, external heating, collar, dexterity, reaction time, carotid arteries
Abstract
The purpose of this pilot study is to test the efficacy of bilateral heating over the carotid
arteries with the external application of commercial hand warmers held in place with a fleece
collar in regards to increasing reaction time, gross motor strength, dexterity, and comfort levels
in cold weather environments. The study was carried out on 15 student volunteers from the
University of Wisconsin Stevens Point campus, split into three groups of five. Students first
underwent tests indoors without treatment intervention. The students were randomly divided in
to intervention groups. Treatment interventions included supplying one third of the students with
heated collars, providing one third of the students with collars without heat (placebo), and having
the last third of the students exercise with the use of no collars. The tests were then repeated
outside after the students had walked in 12 degree Fahrenheit winter weather for 23 minutes. The
test used to measure dexterity was the nine-hole seated peg test. The test for measuring grip
strength was the Smedley Digital Grip Test dynamometer. The test used to measure reaction
time was the reaction time test developed by Michigan State University. Comfort levels were
assessed using a Likert Scale. The results of the study show the heated collar group consistently
outperforming both the placebo group and the no collar group in both the physical tests and in
comfort levels.
Introduction
This pilot study was done to test the efficacy of the product known as the “Chill Killer”
which provides bilateral heating over the carotid arteries with the external application of
commercial hand warmers held in place with a fleece collar. It is hypothesized to increase
reaction time, gross motor strength, dexterity, and comfort levels in cold weather environments.
This is from the assumption that the collar, designed to hold the hand warmers, will be an
efficient method for introducing heat to the blood system, and thus the body, by the dissipation
of heat through the skin and arterial walls. The heat will then travel through the blood to the
peripheral extremities warming the hands which will increase their performance in physical tests
and increase the comfort levels of the individual. Several tests were used including the nine-hole
seated peg test (Cooper, C. 2007), Smedley Digital Grip Test dynamometer (Mitrushina, M.
2005), reaction time test (JAMES T. ECKNER, 2009), and use of a Likert Scale.
Methods
The study was carried out on 15 student volunteers from the University of Wisconsin
Stevens Point campus. Participants were asked to show up to a room on campus wearing a
hoodless sweatshirt and sweatpants. Students first underwent all tests indoors without treatment
intervention. The students were then randomly divided into three intervention groups of five
each. Treatment interventions included supplying one third of the students with heated collars,
providing one third of the students with collars without heat (placebo), and having the last third
of the students exercise without collars. The tests were then repeated outside after the students
had walked in 12 degree Fahrenheit winter weather with treatments for 23 minutes, the time it
took for verbal complaints, with their hands exposed to the cold.
The reaction time test used a novel apparatus developed by the department of physical
medicine and rehabilitation at the University of Michigan, which consisted of a 1.3 meter in
length dowel embedded into a weighted rubber disc. The reaction time test consisted of
catching the device after it was dropped between the student’s thumb and forefinger, with the
reaction time being measured by the distance the disc had fallen before the hand could be closed.
Better reaction times were associated with shorter distances dropped and were reported in
average percentage changes. The test for gross motor strength was carried out using a Smedley
Digital Grip Test dynamometer, which measured pounds of pressure exerted by the dominant
hand. Better performances were measured by percent increases in pounds of pressure. The test
for dexterity was the nine-hole seated peg test, where students were asked to insert nine pegs into
nine holes with their dominant hand while being timed. Better performances associate with faster
exercise completion times. Participants’ comfort levels were assessed using a Likert Scale
questionnaire.
Results
The reaction time test showed the group with heated collars was the only group to have
increased in performance while testing in the cold. They had an overall decrease of 13% in the
distance the dolly dropped before being caught. The placebo and no collar group both increased
their distances dropped, which associates with slower reaction time, with percent increases of
42% and 23% respectfully (Table 1, Figure 1).
At a 5% increase in average pounds of pressure, the heated collar group had the highest
increase in performance with the dynamometers. In a very close second place was the no collar
group at 4% increase and lastly was the placebo collar group which actually decreased 4%
(Table 2, Figure 2).
The nine hole seated peg test showed no overall change in the heated collar group’s
performance which indicated no change in dexterity. However, both the placebo collar and the
no collar groups showed decreases in dexterity by increases in the time it took to finish the
exercise by 8% and 25% (Table 3, Figure 3).
The Likert Scale revealed a pattern of increased comfort, warmth, and alertness
associated highest with the heated collar group followed by the placebo group and then the no
collar group. The statement “My overall level of physical comfort is better now than before any
exercise” had the highest agreement rates among the heated collar treatment group followed by
the placebo group and no agreement with the no collar group. The statement “My hands feel
warmer now than they did before the exercise” only had agreement within the heated collar
group and total disagreement in the other two groups. The statement “My overall level of mental
alertness is better now than before any exercise” also showed that the heated collar group had the
highest agreement rating followed once again by the placebo group and no collar group. The
statement “There is less discomfort in my hands than there was before any exercise” followed
similar trends as the other questions in that the heated collar group had the highest rate of
agreement followed by the placebo group and total disagreement in the no collar group (Table 4).
Discussion
The major patterns found in the data support the hypothesis that bilateral heating over the
carotid arteries with the external application of commercial hand warmers held in place with a
fleece collar in can increase reaction time, gross motor strength, dexterity, and comfort levels in
cold weather environments. The physical tests all showed the heated collar treatment to be the
most effective at increasing or maintaining performance. The Likert Scale mirrored this finding
with the comfort levels being consistently highest in the heated collar group.
The heated collar group repeatedly outperformed the placebo and no collar groups. The
placebo and no collar groups showed variation in how well they outperformed each other which
indicates that the aggressive application of heat is mainly responsible for the increases in
performance rather than the shielding effect of the collar against the environment. It is unclear
why the grip test results showed such a small difference in results compared to the other tests.
One possible reason could be the increased activity of the forearms in gross motor contractions
which were underneath the sleeves of the sweatshirts and not directly exposed to the cold
environment while the fine motor movements of the reaction time test and nine hole peg test
relied more upon muscle groups located in the hands.
The Likert Scale showed considerable empirical evidence that the heated collar increased
comfort levels of the participants most of the three groups. The placebo collar also outperformed
the no collar treatment on every question which it did not do during the physical tests. This may
be due to the collar acting as a barrier for the neck from the cold environment.
Further investigation into the bilateral heating of the carotid arteries with the external
application of commercial hand warmers held in place with a fleece collar needs to be done to
confirm the results of this study. The use of precise statistical methods was not applicable
because of the limited number of participants and thus statistically significant results were
unattainable. Future studies should also consider longer exposure to the cold weather
environment which was not possible for this study due to time constraints of the participants.
In conclusion the heated collar group performed the best in both physical tests and the
Likert Scale because of the application of heat and not the collar itself. The application of the
heated collar in cold weather environments increases reaction time, dexterity, grip strength, and
comfort levels.
Reaction Time Test (cm.)
(Note: Least percent increase equals best result.)
heated collars pre
walk
20.5 29
17
average
22.1666
7
28.3333
3
32.8333
3
35.5
37
30
18
44
32
22.5
33
20.5
53
30
27.5
23
26.8333
3
placebo collars
pre walk
23.5 12
13
average
21
26.5
15.5
16.1666
7
21
30.5
24
29.5
28
21
32
18.5
35.5
24
24.5
23.8333
3
28
No collars pre
walk
28
21 23.5
average
24.1666
7
21
18
10
16.3333
3
30 32.5 26.5 29.6666
7
34 20.5 19.5 24.6666
7
44
27
23
31.3333
3
Table 1 Reaction Time Test
heated collars
post walk
18
31
2
7
30
20.5 2
1
25
23
2
1
30
20.5 3
3
22.5
25
2
4
placebo collars
post walk
15
16
5
6
37
36
2
3
59.5 30.5 2
3
34
32
2
1
29
49.5 2
2
No collars post
walk
29.5
17
2
0
23.5
27
2
3
36
56.5 3
4
33.5
31
1
5
38
42
3
6
average
25.3333
3
23.8333
3
23
Percent
Change
14%
-16%
-30%
27.8333
3
23.8333
3
-22%
average
29
Percent
Change
79%
32
52%
37.6666
7
29
35%
33.5
20%
average
Percent
Change
-8%
22.1666
7
24.5
Average Percent
Change
-13%
-11%
Average Percent
Change
42%
22%
50%
42.1666
7
26.5
42%
38.6666
7
23%
7%
Average Percent
Change
23%
Centimeters Dropped
Reaction Time Tests
45
45
40
40
35
35
32.2333
30.8
30
29.1333
25
25.2333
24.7667
30
25
23.4
20
20
15
15
C1
C2
C3
C4
C5
C6
Figure 2: Group C1 = heated collar, Group C3 =placebo collar, and Group C5 =no collar
during indoor testing (before exercise).
Group C2 =heated collar, Group C4 =placebo collar, and Group C6 =no collar during
outdoor testing (after intervention and exercise).
(Note: Least percent increase equals best result.)
Grip Test (lbs. pressure)
(Note: Most increase in grip strength equals best result.)
Heated collar pre
walk
75.8
80.4
63.4
66
73.4
74.8
41.6
26
103.8
127
averag
e
78.1
64.7
74.1
33.8
115.4
heated collar
post walk
62.8
64
64
70.2
75.8
77.2
31
40.2
158.6
149.2
averag
e
63.4
67.1
76.5
35.6
153.9
Percent
Change
-19%
4%
3%
5%
33%
Average Percent
Change
5%
placebo collar pre
walk
84.8
88.6
108.4
122.2
115.6
111.8
78.2
91.8
59
58.8
averag
e
86.7
115.3
113.7
85
58.9
placebo collar
post walk
84.6
82.4
90
120
105.4
118.8
89.8
88.4
47.4
55.6
averag
e
83.5
105
112.1
89.1
51.5
Percent
Change
-4%
-9%
-1%
5%
-13%
Average Percent
Change
-4%
averag
no collar post
e
walk
131.6
119.8
125.7 152.8
159.4
110.4
106.8
108.6 120.4
131
72.4
71
71.7
68.8
70.6
107.6
110.6
109.1
97.8
92.2
110
107.2
108.6 103.2
104.5
Table 2 Smedley Digital Grip Test
averag
e
156.1
125.7
69.7
95
103.85
Percent
Change
24%
16%
-3%
-13%
-4%
Average Percent
Change
4%
no collar pre walk
Lbs Pressure
Grip Strength
150
150
125
125
110.07
104.74
100
91.92
100
88.24
79.3
75
75
73.22
50
50
C1
C2
C3
C4
C5
C6
Figure 2: Group C1 = heated collar, Group C3 =placebo collar, and Group C5 =no
collar during indoor testing (before exercise).
Group C2 =heated collar, Group C4 =placebo collar, and Group C6 =no collar during
outdoor testing (after intervention and exercise).
(Note: Most increase in grip strength equals best result.)
Nine Hole Peg Test (time sec.)
(Note: Least increase in test time equals best result.)
Heated collar pre
walk
15.36
17.74
15.29
14.46
16.97
12.71
19.97
13.76
15.29
14.2
average Heated collar post
walk
16.55
18.37
19.49
14.875 15.57
13.62
14.84
12.81
12.99
16.865 17.74
16.13
14.745 16.34
13.9
average Percent
Change
18.93
14%
14.595 -2%
12.9
-13%
16.935 0%
15.12
3%
Average %
Change
0%
placebo collar pre
walk
12.31
11.87
15.92
13.62
18.58
16.7
18.44
13.62
14.87
13.69
average placebo collar post
walk
12.09
13.62
14.18
14.77
16.06
15.01
17.64
22.7
21.7
16.03
13.76
12.22
14.28
16.27
16.45
average Percent
Change
13.9
15%
15.535 5%
22.2
26%
12.99
-19%
16.36
15%
Average %
Change
8%
no collar pre walk
average no collar post walk
average Percent
Change
17.79
5%
17.18
19%
16.655 11%
29.58
73%
15.535 18%
Average %
Change
25%
18.37
15.57
16.97
15.51
13.48
14.495
15.64
14.39
15.015
17.11
17.04
17.075
12.78
13.62
13.2
Table 3 Nine Hole Peg Test
18.16
16.62
15.78
25.7
14.35
17.42
17.74
17.53
33.46
16.72
Seconds
Nine Hole Peg Test
30
30
25
25
20
19.348
15
16.197
15.696
15.575
20
15.351
14.962
15
10
10
C1
C2
C3
C4
C5
C6
Figure 3: Group C1 = heated collar, Group C3 =placebo collar, and Group C5 =no
collar during indoor testing (before exercise).
Group C2 =heated collar, Group C4 =placebo collar, and Group C6 =no collar during
outdoor testing (after intervention and exercise).
(Note: Least increase in test time equals best result.)
Post-Exercise Questionnaire
Agree
My overall level of physical comfort is better now than
before any exercise.
(Note: Best result equals least disagreement or most
agreement.)
My hands feel warmer now than they did before the
exercise.
(Note: Best result equals least disagreement or most
agreement.)
My overall level of mental alertness is better now than
before any exercise.
(Note: Best result equals least disagreement or most
agreement.)
There is less discomfort in my hands than there was
before any exercise.
(Note: Best result equals least disagreement or most
agreement.)
2
Disagre
e
1
2
2
0
4
1
3
0
5
0
5
4
0
3
0
0
4
2
1
0
4
0
5
Neither Agree
nor Disagree
2 Heated
Collar
1 Placebo
Collar
1 No Collar
1 Heated
Collar
0 Placebo
Collar
0 No Collar
1 Heated
Collar
2 Placebo
Collar
1 No Collar
2 Heated
Collar
1 Placebo
Collar
0 No Collar
Acknowledgements
The testing strategies were developed through consultation with Appleton, Wisconsin
area medical professionals. Julie Strutz, an occupational therapist with the Hand and Upper
Extremity Center of Northeast Wisconsin (920-730-8833, www.handtoshoulderwisconsin.com),
recommended the seated nine hole peg test as the best standardized test for fine motor
coordination. She stated that this tool could be easily constructed by the researchers rather than
having to be purchased, and the results are standardized for this tool. For gross motor strength
she recommended the dynamometer, and a set of Smedley Digital Grip Testers are available for
this testing.
Dr. Weibel is a sports medicine trained osteopathic physician working with both the
Orthopedic and Sports Institute and also the No Pain Group in Appleton, Wisconsin (920-7337726, 920-560-1060 Ext. 7, jweibel@nopaingroup.com). She provided access to articles
describing the construction and standardization of a novel apparatus used to measure clinical
reaction times by the department of physical medicine and rehabilitation at the University of
Michigan. This device, studied in 2009 and reported in the journal Perceptual and Motor Skills,
consists of a 1.3 meter in length dowel embedded into a weighted rubber disc and is easily
reproducible for this research project.
References
Cooper, C. (2007). Evaluation of the Hand and Upper Extremity. In Fundamentals of hand
therapy: Clinical reasoning and treatment guidelines for common diagnoses of the upper
extremity (pp. 90-93). St. Louis, Miss: Mosby Elsevier.
Mitrushina, M. (2005). Grip Strength (Hand Dynamometer). In Handbook of normative data for
neuropsychological assessment (2nd ed., pp. 444-447). Oxford: Oxford University Press.
James T. Eckner, Ross D. Whitacre, Ned L. Kirsch, and James K. Richardson (2009) Evaluating
a Clinical Measure of Reaction Time: an Observational Study. Perceptual and Motor Skills:
Volume 108, Issue , pp. 717-720.