Temperature Regulation

1
Temperature Regulation

• Kin/NuFS 163
• Mike Sullivan

2
Outline

• Regulation of Body temp
• Hyperthermia during exercise
• Effects on Performance
• Heat Illnesses
• Acclimatization
• Exercise in Cold

3
Regulation of Body Temp

• 4 Mechanisms for heat loss
• Conduction
• Convection
• Radiation
• Evaporation

4
Hyperthermia During Exercise

• Environmental Factors
• Increased Blood Flow to Skin (less oxygen to
  muscles)
• Decreased IC EC water, SV, CO
• Lactic acid increases
• Glycogen use increases
• Blood Volume Decreases, body attempts to maintain
  BP stops sweating
• Less Effective Cooling Increased Core temp

5
Effect on Performance

• Strength, Power, Speed lt 1 min usually not
  effected
• Aerobic Activities
• lt 2 loss of BW impairs performance
• 10 loss possible death
• May effect Mental Function

6
Heat Stress

• Contributing Factors
• Increased Core Temp
• Loss of body fluids
• Loss of electrolytes
• Heat Stress Hazards
• Continuum, Kind of

7
Heat Stress Hazards

• Minor Heat Illnesses
• Heat Cramps Intense muscle spasms in legs, arms
  abdomen
• Causes Fluid Sodium deficits, intense muscular
  activity, environmental heat
• Heat Syncope Fainting, dizziness, weakness
• Causes Pooling of blood in venous circulation,
  dehydration, inactivity

8
Heat Stress Hazards

• Heat Exhaustion Mild to moderate illness
  inability to sustain cardiac output moderate
  body temperature
• Signs and Symptoms
• Stop activity, replenish fluids

9
Serious Heat Illnesses, cont.

• Heat Stroke severe illness, CNS dysfunction,
  body temp gt 105 degrees F
• Signs and Symptoms
• Types
• Classic Occurs in elderly, or otherwise
  compromised populations (sick)
• Exertional Occurs in healthy, physically fit
  individuals
• Emergency Cool immediately

10
At Risk

• Children and Older adults
• Unfit
• Obese
• Previous Heat injury
• Unacclimated

11
Reducing Risk

• Check temp humidity
• Avoid exercising during heat of day
• Exercise in shade
• Minimal clothing loose, white or light colored,
  porous
• Run into the wind during last part of workout
• Hyperhydrate and rehydrate
• Be award of signs and symptoms
• Acclimate

12
Adaptations

• Acclimation vs. Acclimatization
• Time Frame
• Specific
• Benefits
• Minimizing Heat Strain
• Improving Performance

13
Minimizing Heat Strain

• Sweating improved
• Sweat gland hypertrophy
• Sweat earlier
• Higher rate of sweat
• Improved distribution of sweat on skin
• Skin blood flow
• Earlier onset
• Metabolic Rate - Lowered

14
Exercise Performance

• Lowered Heart Rate, Sodium Loss
• Increased Total Body Water, Stroke Volume, Blood
  and Plasma Volume
• Improved Myocardial Compliance, Fluid Balance,
  Thirst, Acquired Thermal Tolerance

15
Time frame of Adaptations

• HR Lowered (3-5 days)
• SV Increased (3-5)
• RPE Lowered (3-5)
• Sweat Na and Cl decrease (6-10)
• Sweat Rate increase (8-14)

16
Heat Acclimation Strategies

• Beforehand
• Increase Cardiovascular Fitness (Interval
  Training)
• Mimic Conditions
• Acclimation
• Minimum 90 minutes per day of heat exposure
• 8-14 days in duration
• Should include some physical activity
• Acclimate in peak heat, train in coolest part of
  day

17
Exercise in the Cold

• Hypothermia
• Frostbite
• Dehydration
• Guidelines
• Check weather
• Dress in layers
• Stop when weather bad or tired
• Drink fluids

18
Prevention

• Inducing Heat Acclimation
• Avoiding Exposure to overwhelming heat stress
• Maintaining adequate hydration
• Be aware of signs and symptoms of serious heat
  illnesses

19
Signs and Symptoms

• Heat Exhaustion
• Rapid pulse
• Body temp under 104 degrees F
• Headache, dizziness, nausea,
• Unsteady walk
• Muscle Cramps

20
Signs and Symptoms

• Heat Stroke
• Weak and Rapid Pulse
• Body Temp above 105 degrees F
• CNS changes Confusion, agitation, blank stare,
  irrational behavior, staggering gait, delirium,
  convulsions, unresponsiveness, coma
• Hot and wet or dry skin
• Hyperventilation
• Vomiting, involuntary bowel movement