Download Potential Issues Resulting from Work Capacity Testing

Potential Issues Resulting from Work Capacity Testing:
The Work Capacity Test is a physical fitness test used by wildland fire fighting agencies to insure firefighters are capable
of working in physically stressful environments. The annual test is conducted at a brisk walking pace (over 4 mph without
jogging or running) while carrying 45 pounds for 3 miles. The test must be completed in less than 45 minutes. A second
test (called the Field Test) is slightly shorter, but still requires a high level of fitness: participants carry 25 pounds for 2
miles, and complete the test in less than 30 minutes.
Several medical situations may arise as a result of fighting fire, and have occurred during
Work Capacity Testing. This brief summary aims to raise the awareness of attending
physicians on the afflictions they may encounter in wildland firefighters.
Aside from the expected cardiac related issues, or muscle strains/joint sprains, the following
aliments have been overlooked, and are briefly summarized as a reminder:
1. Dehydration
2. Heat illnesses
3. Compartment syndrome
4. Rhabdomyolysis
1. Dehydration:
Dehydration occurs when more fluid is lost than is taken in, and the body doesn't have enough fluid to
carry out normal functions. While hot, humid weather increases the amount of fluid lost to sweat,
dehydration can occur at any temperature. Anyone who exercises can become dehydrated, but
athletes who train for extreme physical situations are at particularly high risk. The longer the exercise,
the more difficult it is to stay hydrated.
2. Heat Illnesses:
Humidity is combined with air temperature to get a true reading of heat impacts. When air
temperature is 95ºF or greater, heat loss occurs via evaporation. When the humidity is over 75%,
evaporation slows and sweating becomes inefficient. If these two conditions occur together
(temperature and humidity respectively above 95ºF and 75%), heat loss diminishes to near zero.
Heat illness is cumulative with multiple exposures over consecutive days. Heat illness can occur
under a wide range of environmental conditions during periods of extended exertion.
Firefighters taking certain antibiotics (tetracycline, Cipro®, Floxin®, etc.) may be more susceptible to
heat illness. Very large firefighters should be watched with extra caution - muscle tissue stores more
water (70 - 80%) than does fat tissue (10%).
There are three types of heat illness:
• Heat cramps are painful muscle spasms due to an imbalance between water and
electrolytes.
• Heat exhaustion patients may be near collapse and usually have profuse sweating, flushed
skin, elevated temperature, dizziness, hyperventilation, and rapid pulse.
• Heat stroke symptoms include sudden collapse and loss of consciousness, pale skin, the
patient may or may not be sweating, and have hot, dry skin. Heatstroke can occur
suddenly, without warning: in Texas in 2011, a 23 year-old firefighter died suddenly of heat
stroke without previously showing any symptoms of heat-related illness.
3. Muscle Compartment Syndrome:
Compartment Syndrome is increased pressure in a muscle compartment: Internally, your arms and
legs are divided into well-defined spaces or “compartments” by a thick membrane called fascia. The
fascia is very strong and non-elastic. Within these compartments are nerves, arteries, veins,
capillaries, tendons and muscles. Because of facia’s inability to stretch, compartment syndrome
develops when swelling occurs inside the compartment. The swelling causes an increase in pressure.
Losing oxygen and nutrients, nerve and muscle cells within the compartment become disrupted and
damaged.
Acute compartment syndrome symptoms include:
• Muscle may feel tight or full
• Pain is intense
• Stretching muscle creates more pain
• Numbness or paralysis
• Difficulty moving foot, tightness
• Visible bulging of the muscle
• Cramping, aching or burning sensation in affected limb, usually lower leg
• Foot drop if nerves are affected (severe cases only)
• Weakness of the affected limb
Compartment syndrome has been mistaken for shin splints. The hallmark symptom of compartment
syndrome is pain that does not go away after taking medication or after elevating the limb. The
symptoms of acute compartment syndrome will usually be progressive and unrelenting. Compartment
Syndrome can escalate into a systemic issue called Rhabdomyolysis (see below).
4. Rhabdomyolysis:
Rhabdomyolysis (RAB-DOE-MY-O-LIE-SIS) is the rapid destruction of skeletal muscle resulting in
leakage of the muscle protein (myoglobin) into the urine. Creatine kinase is also in muscle cells. The
levels of these proteins can be measured in the blood to monitor the degree of muscle injury from
rhabdomyolysis. Myoglobin can also be measured in samples of urine.
Rhabdomyolysis has many causes. Some of the common ones include:
• muscle trauma,
• extreme physical activity,
• low circulating electrolytes (phosphate, potassium, or magnesium) in the blood,
• genetic muscle diseases,
• medications: most notably statins used to treat high cholesterol
http://www.medicinenet.com/script/main/art.asp?articlekey=320 and other medications such as
Parkinson’s medication, psychiatric medications, anesthesia medications, HIV medications,
and even some high blood pressure medications,
• variety of viruses and some bacteria,
• lack of blood perfusion to a limb,
• some inflammatory disorders of the muscle
Rhabdomyolysis may not present any symptoms. Usually, muscle aches and pain stiffness, and
weakness occur. Patients may experience a darkening of the urine due to accumulation of proteins.
This causes a strain on the kidneys, often leading to kidney failure. Rhabdomyolysis is confirmed by
blood and urine testing. Blood tests include a complete blood count (CBC), a metabolic panel, muscle
enzymes, and urinalysis. Muscle enzymes include creatine phosphokinase (CPK), SGOT, SGPT, and
LDH. Of note, CPK is also in cardiac muscle and the brain. The laboratory is usually able to
distinguish between the different sources of this enzyme.
-End-