Lecture 20 - Heat and Hydration Flashcards
1
Q
what is the number one rule of sports issues in heat?
A
- when it starts to go poorly, it progresses fast
- you cannot beat physiology
2
Q
how does atmospheric temperature affect body temperature?
A
- as the atmospheric temperature increases, the gradient decreases
- Tbody > Tenvironment = lose heat via radiation
- over 27 C = the body absorbs heat (hard to dissipate it)
- heat loss is from evaporation (sweat) only
3
Q
how is heat generated during exercise?
A
- by endogenous sources (muscle activity and metabolism)
- by exogenous sources (heat transfer when air is > 27 C, or hotter than the body)
4
Q
how does humidity affect body temperature?
A
- increased humidity = decreased vapour gradient = less evaporation
- more humid = less sweat loss = hotter temperature
- increased body temp due to decreased sweat evaporation
- substantial humidity even at low temperatures can be dangerous
5
Q
what is exertional heat stroke?
A
- exertion-related hyperthermia
- temperature over 40 C
- CNS disturbance and organ system damage
6
Q
what are the symptoms of exertional heat stroke?
A
- dizziness
- weakness
- nausea
- fast pulse and respiration
- mental confusion
- potential unconsciousness/collapse
- may stop sweating (hot, dry skin) –> red flag
7
Q
what is heat exhaustion?
A
- inability to continue functioning in the heat
- without evidence of EHS
- a precursor to heat stroke
8
Q
what are the symptoms of heat exhaustion?
A
- heavy sweating
- pale, moist, cool skin
- headache
- weakness
- dizziness
- nausea (with or without vomiting)
9
Q
how do you manage heat exhaustion?
A
- up to 2L of fluid for up to 1 hour (sideline)
- rest in the shade, cooling, rehydration, frequent vital signs and mental status assessment (every 5-10 mins)
- if not recovering, send to the ER asap
10
Q
how do you manage heat stroke?
A
- cool first, transport second
- aggressive cooling within first 1/2 hour
- remove gear
- ice/water submersion (unless risk of drowning) –> armpits and groin under
- rehydration (IV if they can’t drink)
- frequent vital signs and mental status assessment every 5-10 mins
- go to the ER asap
- require immediate evaluation
11
Q
what are the intrinsic risk factors of heat stroke?
A
- lack of acclimatization
- fever
- overweight/obesity (insulator)
- dehydration
- recent alcohol use
- sunburn
12
Q
what are the extrinsic risk factors of heat stroke?
A
- hot, humid environment
- exercise intensity
- inappropriate work-to-rest ratio
- equipment/clothing
- education (athletes, coaches and medical staff)
- lack of emergency plans to identify/treat
- lack of proper infrastructure (heat acclimatization)
- access to fluids
- access to preventative cooling strategies
13
Q
what are the 5 concepts for combatting heat illness?
A
- get an accurate temperature
- keep them/get them cool
- allow time for acclimatization
- train coaches and players on the signs
- keep them hydrated
14
Q
how can you get an accurate temperature?
A
- do not trust forehead/ear temperatures
- rectal is the only accurate (which will not be done on field)
- if the temperature is slightly lower, and symptoms are present, assume EHS
15
Q
how can you keep/get athletes cool?
A
- gradually add more equipment as practices start back up (summer)
- use cold water/ice submersion to cool temp fast (armpits under)
- use cold packs on groin and armpits only when submersion is not possible
16
Q
how can you allow time for acclimatization?
A
- improve cooling mostly through increased sweating/evaporation
- less effective in high humidity
- may need to add electrolytes (not just water)
- progressive and prolonged elevation of the body’s temperature
- does not work if the athlete isn’t exercising
- takes 1-3 weeks for exercise-heat exposure before effective
17
Q
how can you train coaches and players on signs?
A
- inform coaches of the risks so they don’t push athletes past their point of stop/rest/rehydration
- do not use exercise as a punishment
- teach them to remove players when signs or symptoms arise
- medical team must educate staff and players
- follow EAPs (completed, understood and followed)
18
Q
how can you keep athletes hydrated?
A
- don’t let them arrive at training dehydrated
- calculate specific individual water recommendations
- prevent excessive dehydration (>2% body weight loss from water deficit)
- balance electrolytes
- will reduce cardiovascular strain (decreased SV and increased HR if dehydrated)
19
Q
what are the 5 risks of hypohydration?
A
- intrinsic factors (sex, body size, acclimatization)
- exercise structure (duration, intensity, frequency)
- availability of fluids (water breaks, stations, fluids available, temperature of fluids)
- environmental conditions (altitude, humidity, clothing/equipment, air flow)
- sport-specific factors (weight loss, appearance-based sports)
20
Q
how do you track hydration changes?
A
- nude body mass before and after exercise (>2% change = dehydration)
- check urine concentration/colour in the morning (yellow = bad)
- thirst in the morning = dehydration (if you are thirsty, it is probably too late)
21
Q
how much fluid is needed to rehydrate?
A
- ~50% more intake than sweat loss (compensate for urine)
- 2-3 glasses per lb of body weight lost
- eat regularly (will supply ~ 1L water from a balanced diet)
22
Q
how to avoid dehydration: pre-exercise
A
- start hydrated
23
Q
how to avoid dehydration: during exercise
A
- maintain water levels (drink early and often)
- use CHO if exercising for >1hr
- optimal concentration = 4% (5% = diarrhea if dehydrated)
24
Q
how to avoid dehydration: post-exercise
A
- correct fluid loss ASAP
- general nutrition and H2O
- add CHO and electrolytes
25
Q
what is hyponatremia? (aka water intoxication)
A
- when an athlete drinks water without electrolytes and dilutes their body
- may occur in heavy sweaters or salty sweaters
- risk if working out for more than 4 hours with excessive rehydration
- very rare
