Observations on Core Body Temperature

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Observations on Core Body Temperature David A.
Fischer, MD, Charles Barta, ATC, Robby Sikka,
BA TRIA Orthopaedic Center
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Outline

• Background
• Results from 2005 Training Camp
• Discussion and Implications

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Heat Related Illness

• 24 Deaths in Football Players since 1995. All
  but one were in High School or College Athletes
• Literature suggests deaths were preventable
• What factors affect core body temperature
• Hot conditions
• Dehydration of players
• Uniforms
• Level of Exertion
• Supplements

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Our Approach

• CorTemp System
• Ingestible Tablet
• Radio-frequency transmission to central unit
• On field monitoring
• A dozen universities and 3 NFL teams
• 20 players measured this preseason on Minnesota
  Vikings

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Protocol

• Players temperature measured every 15 minutes
  during practice(2 Highest Temps averaged for
  study)
• 10 practices over first five days of camp
• Body weights recorded before and after practices
• Environment recording
• Wet bulb Temperature
• Humidity
• Heat Index

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Results

• Relationship between Weight Loss and Core Body
  Temperature
• There was a correlation coefficient of .2207
  between core body temperature and percentage
  weight loss
• Relationship between Wet Bulb Temperature and
  Core Body Temperature
• There was a correlation coefficient of .2609
  between wet bulb temperature and core body
  temperature

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Results

• Players measured with helmets on during sideline
  inactivity
• Players removing their helmet lowered their core
  body temperature by an average of .5 F for each
  ten minutes they had their helmet off.
• Players who drank cold water, removed their
  helmet, and stood in the shade were able to cool
  at a rate of 1 F every 7 minutes.

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Results

• Players measured while they were in ice tubs. (No
  pads)
• Players cooling themselves in ice baths after
  practice were able to lower their core body
  temperature by 1 F for every five minutes in the
  pool.

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Results

• Players suffering from muscle cramps lost an
  average of 3.13 lbs or 1.1 of their body weight
  average during the single practice session during
  which they had cramps.
• Players who did not suffer from muscle cramps
  reported an average weight loss of 3.10 lbs, or
  1.1 of their body weight in a single practice
  session.
• The average temperature was 102.20F for players
  who had cramping episodes who also had their
  temperature measured using the CorTemp system.

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Discussion

• Difficult to control and consistently measure
  players every 15 minutes
• Relationship of temperature to weight loss and
  environmental temperature were not strong
  associations
• Other factors involved with Core Body Temperature
• Supplements
• Body habitus
• Uniforms
• Position and level of exertion
• How much a player runs
• Other

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Discussion

• Players with the highest temperatures in our
  study were those involved in more running drills
  and those who were on the field for extended
  periods of time with no breaks (lineman and backs
  who were on special teams).
• Veterans being measured may have arrived in camp
  in better shape, and thus were able to
  acclimatize easier
• Rookie players are likely slower to acclimatize
  to the rigorous conditions of two-a-day practices
  in the NFL
• Fowkes data reached a similar conclusion, that
  weight loss was a poor predictor of core body
  temperatures.

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What this means
Thus one can likely conclude that heat illness
and heat illness, while more likely in extremely
hot conditions, can occur in relatively mild
conditions in larger athletes who are dehydrated
and have other physical factors causing stress on
their body.
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Discussion

• Was the cooling of these players due to the
  inactivity of the player versus the actual
  cooling mechanisms?
• We are in the process of developing a more
  rigorous protocol that will allow us to measure
  cooling in a more controlled situation that will
  also enable us to account for inactivity, as well
  as compare different cooling techniques.

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Things to remember

• Treat the player not the temperature
• Players should take their helmet off, drink
  fluids, and stand in the shade during breaks
• Watch for players with high temperature set
  points
• Rookies, special teams players, and offensive
  lineman tend to be the warmest
• Cold water immersion is still best in the case of
  an emergency

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Thank you