2012. Vol.3, No.8, 613-615
Published Online August 2012 in SciRes (
Copyright © 2012 SciRes. 613
Reduction of Fear by Intense Aerobic Exercise Approaching
Physical Exhaustion
Newell Heywood, Susan Sabado, Bernaden De Leon
2309 Langdale Avenue, Eagle Rock, California, USA
Received May 2nd, 2012; revised June 10th, 2012; accepted July 7th, 2012
This pilot experiment was done to test the hypothesis that physical exhaustion can cause a reduction in a
person’s fear level. The efficiency of intense aerobic exercise approaching physical exhaustion has been
investigated as an effective part of therapy for reduction of an individual’s fear reaction. The participants
were 5 males and 5 females, aged 30 - 40 years old. Treatment sessions were conducted over a 1 week
period where subjects first took physical check-ups to determine their physical fitness to undergo intense
aerobic exercise. Subjects met in a gym within a one-week period with 3 sessions of intense aerobic exer-
cise, with a one day rest period after each session. They took pre-test and post-tests using the Fear Ques-
tionnaire to set their current fear levels respectively. Findings showed that there is a significant change
seen in the respondents in the reduction of fear through physical exhaustion by the use of intense aerobic
exercises 1.
Keywords: Endorphins; Physical Exhaustion; Strenuous Exercise; Reduction of Fear; Runner’s High;
Virtual Reality; Fear
Why exhaustion? Exhaustion is a marker in the same way
that street signs mark locations. A member of this research
team observed that when flying terrified and facing his fear by
flying anyway he was never helped the next time he flew. The
next time he was still just as terrified as the time before. Then
in 1984 after attending the Fear of Flying clinic at San Fran-
cisco International Airport (SFO), where they were taught to do
relaxation exercises, the team member flew from SFO to Miami,
Florida, doing relaxation exercises until exhaustion set in and
the relaxation exercises couldn’t be done any more. At that time
he realized his fear had vanished. Later, on the internet he ran
across an article written by some soldiers who claimed they had
lost their “normal fears” after an exhausting bivouac. So that is
why exhaustion became a marker. Those observations of single
events, it turns out, have experimental evidence which back
their validity.
Ströhie et al. (2005) demonstrated in an experiment that
aerobic exercise is effective in treating panic and panic attacks.
An experiment performed in 2003 demonstrated that exercise
induces analgesia and sedation in the body (Sparling, Giuffrida,
Piomelli, Rosskoph, & Deitrich, 2003). Later in 2008 an ex-
periment of “runner’s high” revealed that long distance running
releases endorphins into the body and a euphoric-like state
happens (Boecker et al., 2008). Boecker’s subjects were tested
at rest and after 2 hours of endurance running (21.5 ± 4.7 km) =
(13.9 ± 2.9 mi).
So what is analgesia and sedation in the body that causes
euphoria? Endorphins are natural body chemicals that occupy
the same receptor sites that opium and marijuana occupy which
raises the threshold of pain however there is recent evidence
which suggests that the feeling of euphoria may also be caused
by some other neural function. Kut et al. (2011) call the other
function the “opioid-insensitive inhibitory circuit”. They gave
the endorphin suppressing drug, naloxone, to subjects who
were feeling pain and others feeling pain whose pain thresholds
were elevated by pleasure. The pain feeling group felt more
pain in the absents of endorphins and the pleasure feeling group
felt no pain increase in the absents of endorphins. It appears
that Kut and his cohorts may have discovered a new function of
This experiment will try to explore the possible change in the
fear level of the respondents by using physical exhaustion as its
treatment method. Findings of this research could pave the way
in furthering our understanding of the possible effects of exer-
cise in alleviating certain mental health related problems.
Research Design
This study employed a quasi-experimental approach called a
“Single group pre-test post-test design” in order to assess the
effectiveness of the exercise treatment with the given sample
participants. This particular design is composed of a single group
of participants who underwent the same evaluation measure-
ment followed by a treatment intervention given by the research-
ers. After each of three experiment interventions were done, a
post-test was immediately conducted to assess the effectiveness
of the intervention to the participants.
This study was undertaken with 10 participants, 5 males and
5 females, ages 30 - 40 years old. Based on available data and
relevant interviews, these respondents possessed significant
varying degrees and diversified types of fear. Their fears in-
clude certain insects, relationship with significant people, fears
of the unknown or future life events and many others. The par-
ticipants were given honorariums to cover their expenses. The
possibility that participant expectancy effects influenced re-
ported fear reduction is a valid concern. Even though the ex-
perimental design wasn’t known to the participants they should
have been able to figure it out after the first experiment and that
possibility cannot be guarded against in such a simple experi-
Fear Survey Schedule Π (FSS Π) was developed by James H.
Geer to measure the responses to commonly occurring fears.
The instrument lists potential fear evoking situations and stim-
uli. A client rates his or her level of discomfort or distress. Each
item is rated on a 7 point scale of intensity of fear. Higher
scores indicate greater fear. The FSS Π is considered a very
reliable instrument with an internal consistency coefficient
of .94 using Kuder Richardson formula 20.
The participants signed informed consent forms to show their
approval to join the experiment. Selection of participants was
done thru purposive sampling wherein all the participants have
fears as shown in the results by the Fear Survey. The ten par-
ticipants took complete physical and laboratory examinations to
determine their fitness to participate in the study. The tests were
administered by the researchers who are practicing psycholo-
gists while the physical examination was conducted by a medi-
cal doctor.
The intense aerobics exercise was instructed by different
aerobic experts in their respective fields and took place in the
35th floor of an air-conditioned gym. The respondents under-
went intense aerobic exercise sessions utilizing all equipments
inside the gym up to the point of their exhaustion (1 - 3/2 hr).
The 3 sessions lasted for two to three hours with an interval of
one day rest period after each session. They were pre-tested
before the exercise intervention was done to verify their current
fear levels and were post-tested after they signaled they were
exhausted, to determine the possible change of their fear level
respectively, using the Fear Questionnaire.
Statistical Analysis
The Mean and Standard Deviation values were used to pre-
sent the current anxiety level of the respondents as measured by
the FSS Π instrument. Also, One Way Repeated Measures
ANOVA was used to test for differences in the effect of ex-
perimental interventions on the same group of subjects by ex-
amining the changes in each individual. Examining the differ-
ences between the values rather than the absolute values re-
moves any differences due to individual responses, producing a
more sensitive and more powerful test.
Table 1 presents the Mean and Standard Deviation results
from the initial pre-test up to the final post-test. Reflected from
the findings, the initial pre-test achieved a 162.60 (34.89) mean
rating which classifies the respondents as having very high
levels of fears. With the application of the exercise program,
results seen from post-test 1 mean of 143.30 (41.47), post-test 2
Table 1.
Mean and standard deviation findings.
Mean Standard Deviation Interpretation
Pre-test 162.60 34.89 very high
Post-test 1 143.30 41.47 high
Post-test 2 122.10 50.14 average
Post-test 3 109.10 50.71 average
mean of 122.10 (50.14) and post-test 3 mean of 109.10 (50.71),
there is a substantial decrease on the fear levels seen in the
respondents n from High to Average.
This experiment was meant only to be a pilot study to alert
the psychological community of the reality of fearlessness pro-
duced by physical exhaustion. Its small budget dictated that
only ten experimental subjects be used without a control group.
It’s obvious that such a small number doesn’t constitute scien-
tific proof and no valid conclusions can be drawn from it how-
ever other experiments, unknown to us at the time, demonstrate
that these experimental results are correct. The other experi-
ments demonstrate that physical exhaustion produces endor-
phins which cause body feelings of sedation, analgesia and
euphoria which are incompatible with fear. So it turned out that
not using a control group didn’t hurt the results of this experi-
ment, the results were exactly what they should have been.
Physical exhaustion, the state where a person can no longer
effectively continue doing exercises, was used as the end of the
intervention because other markers or procedures weren’t
known to us at the time. However there are other strategies that
can be used. Ströhie et al. (2005) demonstrated in an experi-
ment that aerobic exercise is effective in treating panic and
panic attacks. They used aerobic exercise for 30 minutes at
70% of maximum oxygen consumption however they made no
claims that endorphins were involved.
This experiment was performed in the third week of March,
2010, in the Fitness First health center on the 35th floor of the
Wynsum building in Manila and wasn’t published until 2012,
however in the intervening time we discovered the experiments
on runner’s high which greatly strengthens these findings.
Those studies have demonstrated that long distance running,
which we equate to physical exhaustion, releases endorphins
inducing analgesia and sedation in the body and a euphoric-like
feeling happens. Thus it appears that endorphins released into
the body by strenuous exercise cause a decrease in a person’s
fear and anxiety level which explains the success of this ex-
It’s obvious that slight or mild diseases and conditions re-
spond best to treatment whereas severe conditions respond less
favorably so. This holds true in the treatment of fear and anxi-
ety also, which is the subject of this report. Numerous studies
of cognitive behavioral therapy conclude that there is a small
percentage, 10% to 15%, of treated clients who get no relief
from their fears at all. Thus the people who have the least fear
get the best results from therapy and those who have the most
fear get none at all. The other anxious people lie somewhere
between those two conditions. Might it be possible that by us-
ing physical exhaustion to lessen a client’s fear, before expo-
sure therapy begins, that he may temporarily transcend out from
the untreatable group into the less fearful more successfully
Copyright © 2012 SciRes.
Copyright © 2012 SciRes. 615
treatable group?
Another possible application of exhaustion reduced fear is in
the treatment of soldiers returning home with post traumatic
stress disorder (PTSD). The US army is using virtual reality at
Walter Reed Hospital in treating PTSD to revive soldier’s re-
pressed memories and thus make them amenable to therapy.
Obviously, fear related stress so powerful that it causes repres-
sion of memories belongs in the “get no relief” (GNR) group.
So when virtual reality revives their repressed memories, the
soldiers are still in the GNR group. Virtual reality therapy has
been reported to be 62% successful, (Reger et al., 2011). That
leaves 38% unsuccessfully treated. Perhaps endorphin releasing
strenuous exercise before virtual reality therapy begins will
improve their success rates. How long the fearlessness state
exists isn’t known and needs to be determined experimentally,
however endorphins in the body exist for a finite time so it
would be best to do the exposure therapy immediately after
exhaustion is produced.
Thus if people temporarily suspended or at least significantly
reduced their fears before therapy by using endorphin releasing
exercises then perhaps they would transfer out of the untreat-
able group and into the more successfully treatable group. An
interesting variation of this procedure would be to use the ele-
vated pain threshold activated by pleasure, in place of exhaus-
tion, as done by Kut and his associates to see what effect that
has. This experiment points to the need for more experiments to
clarify the exhaustion-reduced-fear phenomena.
Susan Sabado and Bernaden De Leon designed, performed
and wrote the experiment results. They are graduate psychology
students at The University of Santo Tomas in Manila. They are
also associated with the Philippine Mental Hospital in Manila.
Special thanks to Bella Z. Canuto who helped make this un-
dertaking possible.
Dr. Romeo Sabado gave the participants physical exams and
was present at all three sessions monitoring their health. He is
the resident neurologist at the Philippine Mental Hospital.
Newell W. Heywood Jr. originated, funded, wrote the intro-
duction and discussion, and had this report published.
Boecker, H., Hendricksen, G., Koppenhoefer, M., Spilker, M. E., Spre-
ger, T., Tolle, T. R., & Wagner, K. J. (2008). The runner’s high:
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Kut, E., Fink, D., Folkers, G., Candia, V., von Overbeck, J., & Pok, J.
(2011). Pleasure-related analgesia activates opioid-insensitive cir-
cuits. The Journal of Neuroscience, 31 , 4148-4153.
Reger, G. M., Difede, J., Gahm, G. A., Holloway, G. M., Candy, C., &
Rothbaum, B. O. (2011). Effectiveness of virtual exposure therapy
for active soldiers in a military mental health clinic. Journal of
Trauma Stress, 24, 93-96. doi:10.1002/jts.20574
Sparling, P. B., Giuffrida, A., Piomelli, D., Rosskoph, I., & Deitrich, A.
(2003). Exercise activates the endocannabinoid system. Neuroreport,
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Ströhle, S., Feller, C., Godemann, F., Heinz, A., Onken, M., & Dimeo,
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