Mirthful Laughter and Muscle Soreness / Pain

Chronic pain affects 116 million people, that is more than the total affected by
cardiovascular disease, cancer, and diabetes combined. Chronic pain has at least as large of
a negative impact on quality of life as any other chronic disorder, and in the United States
alone, the cost of chronic pain exceeds $635 billion per year. Interventions that effectively
manage chronic pain are becoming increasingly important as the elderly population, who often
suffer from osteoarthritis and low back pain, rises. Pain sensitivity and tolerance are
impacted by a variety of affective factors. The laughter therapy is one of the most discussed
and often controversial strategies for the management of pain. There are some preliminary
uncontrolled studies reporting that pain tolerance is increased acutely with humor and
laughter. Accordingly, the primary aim of the present study is to investigate the effect of a
highly controlled intervention with a comedy video on pain tolerance and compare it to a
control of watching a documentary video. Quantitatively measuring laughter with a chest
stress-strain gauge during the interventions will allow the investigators to look for a
possible dose response relationship. The investigators will use the pain and soreness felt
from delayed onset muscle soreness (DOMS) in healthy subjects to simulate the condition of
individuals suffering from chronic pain. This study will serve as a precursor to eventual
studies specifically on individuals with chronic pain. If it can be proven that pain
tolerance is increased in a healthy population than it is possible the intervention will have
a greater affect in the chronic pain population.

Using healthy subjects with delayed onset muscle soreness allows the investigators to easily
recruit and control for other diseases or disorders that may accompany a chronic pain
individual.

There have been a number of different techniques used to assess pain tolerance. The modes of
stimulating pain used in previous studies of laughter and humor on pain tolerance remain
controversial. These studies utilized the cold pressor test and the inflation of a blood
pressure cuff to elicit pain. Both of these methods are known to elicit marked cardiovascular
responses along with the pain responses. An important part of the pain regulatory process in
humans is that there is a functional interaction between the cardiovascular and pain
regulatory systems. The brain regions underlying control of the cardiovascular system are
known to overlap substantially with those that contribute to anti-nociception. Accordingly,
it is difficult to determine how much of the pain tolerance is affected by cardiovascular
reflexes. Thus, the secondary aim of the present study is to test how much cardiovascular
responses will be elicited by a variety of methods of eliciting pain (pumping up a blood
pressure cuff, the cold pressor test, and the application of blunt force on muscles).

The application of blunt force will be used to elicit pain without causing a systemic
response involving cardiovascular reflexes which is seen in the cold pressor and inflation of
a blood pressure cuff. The investigators believe these vast cardiovascular responses may
cause pain tolerance to not be truly measured. It has been inferred that blunt force applied
within a few seconds to a local, specific spot on the quadriceps will not stimulate a
systemic and cardiovascular response and thus the pain tolerance measurement will be more
accurate if independent of cardiovascular responses. Pressure and force application is widely
used as an experimental pain stimulus, but it has not been utilized in the context of
laughter and pain.

Inclusion Criteria:

- Between the age of 20 and 40

- Considered healthy

Exclusion Criteria:

- Candidates that are on cardiovascular acting drugs.

- Candidates currently taking anticoagulants.

- Candidates that have chronic pain or other musculoskeletal injuries.

- Candidates with a body fat percentage less than 5%.

- Candidates with bleeding disorders or neurological disorders

- Raynaud's disease

- History of severe frost bite.