Diving Response Report

1. ‘
The human diving response with greatest
effect at certain temperatures in relation to
face, feet and forearm immersion
Yule, Steven1
n8601321and Du Toit, Cavan1
n8638338
1 School of Exercise and Nutrition Sciences, Queensland
University of Technology, Brisbane, Australia
Tutor: Aaron Bach
Tutorial Time: Thursday 2-4pm

2. 2
Introduction:
As free divers begin to descend to depths in excess of 100 meters, the human body
begins to go through a variety of different physiological sensations and responses in
order for the diver to hold their breath for a prolonged period of time. The diving
response is triggered during apnoea or cold stimulation of the face or limbs which
garners differing responses from the respiratory, cardiac and vascular systems (2).
The diving response is achieved via stimulation of cold-receptors in the superior
region of the face which is stimulated by the ophthalmic branch of the trigeminal
nerve which causes this response (5). It is characterised by a decrease in cardiac
output, bradycardia which is the slowing of one’s heart rate, and peripheral
vasoconstriction or the restriction of blood flow to certain organs only (1, 5).
In order for a free diver to reach his maximum depth, and for the diving response to
be as effective as possible, the facial receptors need to be optimally stimulated by
water at a specific temperature. The aim of this study is to discover the temperature
of water where the largest diving response in humans is greatest, and whether the
greatest diving response is achieved via feet, forearm, or facial immersion.
For the initial phase of this study it is hypothesised that a water temperature of 10o
will result in the greatest diving response. In order for a second hypothesis to be
made, results need to be analysed from the first experiment in regards to which
temperature is most optimal. Once this has been done it is hypothesised that the
diving response will be greatest with face immersion compared to forearm or feet
immersion at the discovered temperature from Part A.
Experimental design:
Hypothesis 1- When the face is immersed in varying water temperatures, 10o will
provide the longest breath hold time and achieve the greatest diving response.
Hypothesis 2- if the forearms, face and feet are immersed independently in 10*
water, the diving response will be most significant when the face is immersed.
The experiment undertaken was designed to uncover the best temperature as well
body part suited to inhibiting the most significant diving response.

3. 3
Subjects
The subjects were 19 years of age; 1 male (187cm, 87kgs) and 1 female (161cm,
59kgs), who exercise regularly and are non-smokers, and had no experience in
breathe-holding activities.
Part A
The two participants performed a series of maximal breath hold tests in 25o, 20o,
15o, 10o, and 5o water. For these tests, room temperature water was poured into a
large bucket, where the water temperature was systematically lowered to the desired
temperature using a thermometer as a reference. A pulse oximeter was used to
continuously monitor and measure the body’s oxygen saturation as well as heart rate
during the max breath hold. Blood pressure, using a sphygmomanometer, was
measured immediately before and after the max breath along with a stopwatch to
time and measure the extent of the diving response. These tests took place with the
subject lying in a prone position on a mat where they lowered their own face into the
bucket. After each temperature was tested, adequate rest (5-6 mins) was given to
the participants between each breath hold.
Note: 5-degrees Celsius was not tested as can be seen in Figure 1and Table 1, due to participant
discomfort with the water being too cold.
Part B
The same two participants undertook further immersion tests but of the bilateral feet
and forearms. For the feet test, the subject was placed in a seated position with the
water bucket placed on the ground in front of them. This allowed them to easily lower
and raise their feet for the duration of the test. For the forearm test, the subjects
were placed in a seated position with the bucket placed on a table in front of them.
The water temperature was set using ice blocks and a thermometer to the
temperature discovered in Part A. A pulse oximeter was used to continuously
monitor and measure the body’s oxygen saturation as well as heart rate during the
max breath holds. Blood pressure, using a sphygmomanometer, was measured
immediately before and after the max breath along with a stopwatch to time and
measure the extent of the diving response. After each temperature was tested
adequate rest (5-6 mins) was given to the participants between each breath hold.

4. 4
Results:
Part A:
As visible in figure 1, the 10 degree face immersion test indicated the largest change
in heart rate (HR) with an average change of 37 beats per minute (BPM) between
the subjects. This test also showed that both the subjects were able to hold their
breaths for the longest period of time with the female subject lasting 60 seconds and
the male subject lasting 85 seconds without breathing. This is a considerable
difference when comparing these results to the 15 degree tests where the female
and male subjects held their breaths for 45 and 60 seconds respectively. As evident
in table 1, it can also be seen that the greatest change in average oxygen saturation
occurred at 10 degrees where the maximum equalled 100% with a minimum of
91.5% (±0.71). This change is larger than the 15 degree test which showed 100% as
maximum and 96 (±4.24) as a minimum average oxygen saturation. Table 1 also
indicates that the change in blood pressure (mmHg) was largest pre and post test in
the 10 degree test compared to the 15 degree test which showed the second largest
change. The 10 degree test showed average pre test blood pressure equalling
106/63 (±17.86/±21.21) with post test measuring equalling 130/80 (±20.51/21.92)
compared to the 15 degree tests pre and post readings of 113/55 (±3.54/±7.07) and
120/73 (±2.83/±7.07) respectively. Finally, Table 1 also indicates that greatest
change in mean arterial pressure (MAP) occurred during the 10-degree test with pre
and post tests recording 77.15 mmHg (±20.01) and 96.15 mmHg (± 10.71)
respectively.
Part B:
Note: Due to these results showing that the longest breath hold and diving response occurred at the
10 degree test, it was decided by the research team that experiment 2 will take place at 10 degrees
where the forearm and bilateral feet tests will be compared to the finding of the face immersion at the
same temperature.
As visible in Figure 2, the bilateral feet and forearm tests had an average HR change
of 30.5 and 18 BPM respectively which are both less than the faces average change
of 37 BPM. The breath-hold times of the bilateral feet and forearm tests equated to
45 and 50 seconds for the female subject and 70 and 65 seconds for the male
subject. This is signicantly shorter than the face immersion tests results of 60 and 85
seconds for the female and male subjects respectively.

5. 5
As seen in table 2, percentage of oxygen saturation changed by 8.5% during the
face test compared to 2% in both the bilateral feet and forearm tests. The average
change in blood pressure was also less in the bilateral feet and forearm tests with
data of 110/78 (±14.14/±8.48) and 114/63.5 (±5.66/±12.02) pre test, and 127/83
(±4.24/±9.9) and 112/73 (±0/7.07) in post test recording. This change is considerably
less than the measures found pre and post during the face immersion test where the
findings were 106/63 (±17.86/±21.21) pre test and 130/80 (±20.51/21.92) post test.
Finally, the MAP of the bilateral feet and forearm tests equated to 88.5mmHg
(±10.61) and 80.3 mmHg (±9.9) pre test, and 97.65 mmHg (±8) and 86 mmHg
(±4.67) post test respectively. Again this is less than the change in the pre and post test
MAP of the face test (77.15 (±20.01) and 96.15 (± 10.71)).
Discussion
Results showed that, at 10-degrees both the subjects were able to hold their breaths
the longest, with the female subject lasting 60 seconds and the male subject lasting
85 seconds. This is a marked difference when compared to 15 degrees where the
female and male subjects held their breaths for 45 and 60 seconds respectively.
Oxygen saturation changed more dramatically at 10-degrees as compared to 15-
degrees. The average oxygen saturation at 10-degrees had a maximum equalled to
100% with a minimum average of 91.5% (±0.71), whereas 15-degrees had a
maximum of 100% and a minimum average of 96% (±4.24) oxygen saturation. Blood
pressure changes were greatest in the 10-degrees pre-test (106/63 (±17.86/±21.21))
and post-test (130/80 (±20.51/21.92)) as compared to the 15-degrees pre-test
(113/55 (±3.54/±7.07)) and post-test (120/73 (±2.83/±7.07)). Mean arterial pressure
(MAP) was again, greatest in the 10-degree test with pre and post-tests recording
77.15 mmHg (±20.01) and 96.15 mmHg (± 10.71) respectively.
These results support the hypothesis that- if the face is immersed in varying water
temperatures, 10o will provide the longest breath hold time and achieve the greatest
diving response. The longest breath holds and diving response were most evident
during face immersion- with an average change of 37 beats per minute (BPM)
between the subjects. During the face test it resulted in both the subjects being able
to hold their breath for the longest period of time with the female subject lasting 60
seconds and the male subject lasting 85 seconds.

6. 6
The bilateral feet and forearm tests only had an average HR change of 30.5 and 18
BPM respectively. Along with this, the breath-hold times of the bilateral feet and
forearm tests equated to 45 and 50 seconds for the female subject and 70 and 65
seconds for the male subject. These data trends support the hypothesis that- if the
forearms, face and feet are immersed independently in 10* water, the diving
response will be most significant when the face is immersed.
A study conducted by Paulev and colleagues found that using 10-degree Celsius
water was associated with a strong, negative chronotropic effect (22% fall in HR),
which developed within 10 s (4). Breath-holding at functional residual capacity (FRC)
reduced HR substantially only in 10 degrees C water, and in contrast to that at total
lung capacity (TLC), the response was slowly developing with a latency of 10-15 s.
All these reductions in HR were significant and accompanied by increases in BP and
MAP. The strong, negative chronotropic effect of cold water was typically linked to a
rise in SV.”
Upon initiation of the diving response, 3 physiological adaptions occur to the human
body. When water makes contact with the face, bradycardia occurs where the heart
rate slows by 10-20%. Colder water has a more dramatic and swift effect. Slowing
down the heart rate increases the amount of blood that can be transported to more
vital organs and functions of the body, like the brain and heart. Bradycardia allows
for maintenance of adequate blood pressure and the heart can beat a lot slower,
also needs less oxygen (6). Peripheral vasoconstriction is induced by deep diving.
The higher pressure at greater depths causes the capillaries in the extremities to
start closing up, fingers and toes lose circulation first, then the hands and feet and
eventually the arms and legs. The musculature in humans only accounts for 12% of
the body’s total oxygen (3). Decreased cardiac output or hypertension sets in with an
increase in mean arterial blood pressure and a maintained or decreased stroke
volume (7).

7. 7
Conclusion:
In conclusion we support hypothesis 1 which states that if the face is immersed in
varying water temperatures, 10* will provide the longest breath hold time and
achieve the greatest diving response- this is supported by the results where oxygen
saturation, blood pressure and MAP data all add up in the favour or 10-dgree Celsius
water when compared to other temperatures. More so, the breath hold times were
significantly different between 10-degrees (female=60seconds, male=85seconds)
and 15-degrees (female=45seconds, male=60seconds).
Hypothesis 2 is also supported which states that if the forearms, face and feet are
immersed independently in 10* water, the diving response will be most significant
when the face is immersed. This hypothesis is also supported by the data where the
breath-hold times of the bilateral feet and forearm tests equated to 45 and 50
seconds for the female subject and 70 and 65 seconds for the male subject. This is
significantly shorter than the face immersion tests result of 60 and 85 seconds for the
female and male subjects respectively.

8. 8
Figure 1:
60
65
70
75
80
85
90
95
100
105
0 10 20 30 40 50 60 70 80 90
HeartRate(bpm)
Time (s)
Heart Rate Responses at Different Temperatures of
Face Immersion
Heart Rate at
25 Degrees
Heart Rate at
25 Degrees
Heart Rate at
20 Degrees
Heart Rate at
20 Degrees
Heart Rate at
15 Degrees
Heart Rate at
15 Degrees
Heart Rate at
10 Degrees
Heart Rate at
10 Degrees

9. 9
Table 1:
Cardiovascular Responses at Different Temperatures of Face Immersion
25 Degrees 20 Degrees 15 Degrees 10 Degrees
Average Maximum
Oxygen Saturation
(%)
99.5 (±0.71) 100 100 100
Average Minimum
Oxygen Saturation
(%)
98.5 (±0.71) 98.5 (±2.12) 96 (±4.24) 91.5 (±0.71)
Average Pre Blood
Pressure (mmHg)
104/57
(±8.49/±16.26)
106/62
(±15.56/±23.33)
113/55
(±3.54/±7.07)
106/63
(±17.86/±21.21)
Average Post
Blood Pressure
(mmHg)
121/63
(±4.95/±21.21)
114/75
(±19.02/±20.5)
120/73
(±2.83/±7.07)
130/80
(±20.51/21.92)
Average Pre Mean
Arterial Pressure
(mmHg)
72.35 (±13.65) 76.35 (±20.72) 74.15 (±5.87) 77.15 (±20.01)
Average Post
Mean Arterial
Pressure (mmHg)
82.15 (±15.77) 87.5 (±20.08) 87 (±6.08) 96.15 (± 10.71)

10. 10
60
65
70
75
80
85
90
95
100
105
110
0 10 20 30 40 50 60 70 80 90
HeartRate(bpm)
Time (s)
Heart Rate Responses at Different Sites of Immersion
at 10 Degrees
Face Immersion
Face Immersion
Feet Immersion
Feet Immersion
Arm Immersion
Arm Immersion
Figure 2:

11. 11
Table 2:
Cardiovascular Responses at Different Sites of Immersion at 10 Degrees
Face Feet Arms
Average Maximum
Oxygen Saturation (%)
100 100 100
Average Minimum
Oxygen Saturation (%)
91.5 (±0.71) 98 98
Average Pre Blood
Pressure (mmHg)
106/63
(±17.86/±21.21)
110/78
(±14.14/±8.48)
114/63.5
(±5.66/±12.02)
Average Post Blood
Pressure (mmHg)
130/80
(±20.51/21.92)
127/83
(±4.24/±9.9)
112/73
(±0/7.07)
Average Pre Mean
Arterial Pressure
(mmHg)
77.15 (±
20.01)
88.5 (±10.61) 80.3 (±9.9)
Average Post Mean
Arterial Pressure
(mmHg)
96.15 (± 10.71) 97.65 (±8) 86 (±4.67)

12. 12
References:
1. Andersson, J., Schagatay, E., Gislén, A., Holm, B (2000). Cardiovascular
responses to cold-water immersion of the forearm and face, and their
relationship to apnoea. European Journal of Applied Physiology, 83, 566-572.
2. Gooden, B (1994). Mechanism of the human diving response. Integrative
Physiological and Behavioural Science, 29(1), 6-16.
3. Lindholm, P. & Lundgren, C. (2008). The physiology and pathophysiology of
human breath-hold diving. Journal Of Applied Physiology, 106(1), 284-292.
http://dx.doi.org/10.1152/japplphysiol.90991.2008.
4. Paulev, P., Pokorski, M., Honda, Y., Ahn, B., Masuda, A., & Kobayashi, T. et
al. (1990). Facial cold receptors and the survival reflex "diving bradycardia" in
man. The Japanese Journal Of Physiology, 40(5), 701-712.
http://dx.doi.org/10.2170/jjphysiol.40.701.
5. Schuitema, K., Holm, B (1998). The role of different facial areas in eliciting
human diving bradycardia. Acta physiologica Scandinavica, 132(1), 119-120.
6. Speck DF, Bruce DS (March 1978). "Effects of varying thermal and apneic
conditions on the human diving reflex". Undersea Biomed Res 5 (1): 9–14.
PMID 636078. Retrieved 2016-05-09.
7. Wittmers, L., Pozos, R., Fall, G., & Beck, L. (1987). Cardiovascular responses
to face immersion (the diving reflex) in human beings after alcohol
consumption. Annals Of Emergency Medicine, 16(9), 1031-1036.
http://dx.doi.org/10.1016/s0196-0644(87)80755-2.