Module 5 - Exercise in Heat and Cold Flashcards
What heat loss comes from evaporation?
- Sweat Evaporation
What heat loss comes from radiation?
- Transmission of heat energy from a surface
What heat loss comes from conduction?
- Transfer of heat from one substance to an adjacent substance
What heat loss comes from convection?
- Transmission of heat to a fluid which moves away from the heat source
What does the evaporation of water from the liquid phase to the gas phase require?
- Heat
What plays a role in humidity?
- HUMIDEX
What is the equation for HUMIDEX?
Humidex = Air Temp + 0.5555x(6.11 x e^5417.7530(1/273.16 - 1/dewpoint in kelvin) - 10)
How does high humidity affect evaporation?
- Interferes with evaporation
What can play a role in humidity’s impact on heat loss?
- Garments
What is an example of Radiation heat loss?
- Space Blankets
What is forced convection?
Fluid going to move anyway
- blood flow
What is free convection?
Heat causes the motion of the fluid
- flow of air around body
What are the Risk Factors for Cold Injury?
- Wheather
- Exhaustion/Dehydration
- Clothing Consideration
- Spinal Cord Injury
- Trauma
What kind of weather is a risk factor for cold injury?
- Wind chill
- Precipitation
How is a spinal cord injury a risk factor for cold injury?
- Impaired Vasoconstriction
- Sensation
How is trauma a risk factor for cold injury?
- Prolonged Exposure
- Direct effect on hypothalamus affecting thermoregulation
What are the Mild Features of Hypothermia?
- Cold Extremities
- Shivering
- Tachycardia
- Tachypnoea
- Urinary Urgency
- Mild Incoordination
What are the features of moderate Hypothermia?
- Apathy
- Poor judgement
- Slurred speech
- Amnesia
- Reduced Shivering
- Dehydration
- Clumsiness
What are the features of severe hypothermia?
- Inappropriate Behaviour
- Loss of shivering
- Arrhythmias
- Pulmonary Oedema
- Hypotension and Bradycardia
- Reduced LOC, muscle rigidity
What is the On-Site management of the hypothermic Athlete?
- Recognition of features
- Removal from cold, windy, or wet conditions
- Minimal handling
- Insulation to prevent further heat loss
- Provision of nutritional
- fluid support assessment
- Possible passive or active rewarming
- Moderate/Severe consider: Transportation to a medical facility
- Monitor for arrhythmia/hypotension
What is passive Rewarming?
- Remove from a cold environment
- Remove wet clothing
- Replace with dry blankets/clothes
- Place the patient in a plastic bag and then insulate
What is Active Rewarming?
- ON-site can use warm packs in axillae, groin, torso
- Heat torso to reduce afterdrop
- Exercise only in very mild hypothermia
- More advanced external/internal rewarming in monitored hospital setting
What are the classifications of Frostbite?
- Superficial: Skin and Subcutaneous Tissue
- Deep: Affecting Bone Joint and Tendon
What is Frostnip?
- Transient numbness and tingling without residual damage
How do you evaluate Blisters?
- Clear = better prognosis
- Cloudy or blood = poor prognosis
- Blisters contain harmful thromboxane’s and prostaglandins
What is the guide to the removal/aspiration of blisters?
- No consensus
- Practice has been to drain clear while leaving hemorrhagic intact
What is the guide for ibuprofen usage to treat hypothermia?
- 400mg
- Counteracts COX vasoconstriction
What will definitive care for frostbite include?
- Rewarming Bath
- Aloe, Dressing
- Eventual Surgical Management
How can we prevent cold injury?
- Education, equipment
- Emollients don’t work
- Vigilant personnel with radios work
What is metabolic cold acclimatization?
- Small increase in metabolic rate
- Includes activation of brown adipose tissue
What is insulative cold acclimatization?
- Enhanced peripheral vasoconstriction
- Better core temperature defense
What are the main points of cold injury knowledge?
- Prevention
- Early Recognition
- ON-site management strategies: passive and active rewarming
What happens when exercising in the heat?
- blood transported to the periphery for cooling
- Relative/actual central fluid deficit
- Splanchnic Vasoconstriction to compensate for peripheral ‘steal’
What does the transportation of blood to the periphery do during exercise in the heat?
- Cooling
What does the relative and actual central fluid deficit during exercise in heat do?
- Leads to smaller cardiac stroke volume
- Resultant increase in heart rate for given intensity
What does splanchnic vasoconstriction to compensate for peripheral ‘steal’ do during exercising in heat?
- leads to GI and Kidney adverse effects
- Kidney Failure
- Ischaemic Gut
- NSAIDs
What types of heat illness are there?
- Heat Stroke
- Heat Exhaustion
- Hyponatremia
How does aggressive and rapid treatment impact heat illness?
- Improves outcomes
What is a feature of heat exhaustion?
- Lack of mental status changes
What are some heat exhaustion symptoms?
- Pale, cool, and moist skin
- Sweating Profusely
- Muscle Cramping, Pain
- Faint or Dizzy
- Headache
- Nausea
What are some Heat Stroke Symptoms?
- Markedly abnormal mental status
- Flushed, hot and dry skin
- Slightly elevated blood pressure
- Hyperventilating
What abnormal mental statuses are associated with heat stroke symptoms?
- Dizziness
- Confusion
- Hallucinations
- Coma
What are the Risk Factors for Heat Illness?
- Age > 65
- Alcohol, Dehydration
- Overweight
- Poor Fitness / sedentary
- Poor Acclimatization
- Recent Fever
- Sunburn or other skin conditions
- Certain Medications
What types of Medications are risk factors for heat illness?
- Reduce Sweating
- Alter Skin Blood Flow
- Increase Heat Production
- Reduce Cardiac Contractility
What are some complications that are involved in Exertional Heat Stroke?
- Mental Status Changes and Tc>40C
- Seizure
- Hypotension
- Rhabdomyolysis
- Liver Damage
- Arrhythmias
- Disseminated Intravascular Coagulation
What weather conditions can exertional heat stroke occur in?
- a variety of weather conditions
What can metabolic heat production contribute to?
- Hyperthermia
What are the causes of death from heat stroke?
- Inaccurate temperature measurement/misdiagnosis
- Inefficient cooling
- Rapid Return to Play
What do you need for a proper diagnosis of heat stroke?
- True Core Temperature
What is an effective cooling strategy for heat stroke?
Must reduce temperature to <40C within 30min
- Ice Bath
- If not available: use 12 ice-d towel in 6:6 rotation
What is the proper protocol for return to play from heat stroke?
- Determine and mitigate the cause
- Full Recovery Necessary
- Deacclimatisation / Deconditioning During Recovery
What are the ACSM guidelines for return to play following Exertional Heat Stroke?
- refrain from exercise for 7 day after medical care release
- Follow-up: 1 week
- Begin Exercise: cool environment / gradual increase 2 weeks
- Vigorous activity: if not by 4wk more tests needed
- full competition:
What is Exercise Associated Hyponatremia (EAH)?
- During or Up to 24 Hours after prolonged physical activity
- Defined by a serum or plasma sodium concentration ([Na+]) below normal reference range
What level of [Na+] shown in the lab is a sign of Exercise Associated Hyponatremia?
- less than 135 mmol/L
What are the early signs of Hyponatremia?
- Bloating
- “puffiness”
- Nausea
- Vomiting
- Headache
What are the serious signs and symptoms of Hyponatremia?
- Alteration of Mental State
- Obtundation
- Coma
- Seizures
- Respiratory Distress (pulmonary edema)
What are the alterations to the mental state during Hyponatremia?
- Confusion
- Disorientation
- Agitation
- Delirium
What happens with weight during Hyponatremia?
- General weight gain in most cases
What is the Aetiology of Hyponatremia?
- Consumption of fluids in excess of total body fluid losses
What are risk factors for Hyponatremia?
- Excessive drinking behaviour
- Weight gain during exercise
- Low body weight
- Female Sex
- Slow performance pace
- Event inexperience
- NSAIDs
- High Availability of drinking fluids
- > 4 hours exercise duration unusually hot environmental conditions
What is the Treatment protocol for Hyponatremia?
- Recognition
- ABCs
- Intravenous Access
- 100ml of 3% NaCl (hypertonic saline)
- Urgent EMS transfer
What are the three pillars of performance in the heat?
- Heat acclimation/acclimatization
- Heat Mitigation: Pre-event / per-event
- Hydration Strategy
Why should athletes planning to compete in hot ambient conditions acclimatize?
- Lowering Physiological Strain
- Improving Exercise Capacity in Heat
How much should athletes undergo heat acclimatization?
- 60mins/day
- Enough to increase skin temp and sweating
Where should athletes perform heat acclimatization?
- same environment as the competition venue
- if not possible, train indoors in a hot room
How long should athletes perform heat acclimatization?
- Ideally, 2 weeks
- See some adaptations around 1 week
When are early adaptations seen from heat acclimatization?
- first few days
- Not complete until around 1 week
What are some pre-competition cooling options?
- Immersion - torso 10-15C
- Vests (ice)
- Slushies / Cool drinks
- Avoid Shivering
- Shorten Warm-Up
What are some cooling options during competition? (per)
- Ice Cold Drinks (water/electrolytes)
- Ice Cold Towels
- Ice Cold Hats
- Ice Necklaces
What is a good Hydration Planning protocol?
- Fluid Tolerability/concentration
- Hand-offs
- Team Communication
- Athlete-Support Team Individual Meetings
- Discuss and Plan Contingencies
What logistics do you need to know to plan ahead?
- Site Visit
- Supplies/Equipment
- Water/ice
- Familiarisation
- Practice Handoffs
What should you avoid when competing in the cold?
- Shivering
- GI distress
