EXAM 4 Flashcards
- person being measured differs from the standard reference body only in the amount of fat
- density of fat is 0.901 gm/cc
- density of fat-free body is 1.100 gm/cc
assumptions for all body compositions
- estimating body composition from body density
- principle/theory: density = mass/volume
- underwater weighing, hydrostatic weight or hydrodensitometry
- bod pod
densitometry
Accuracy of H20 weighing:
- considered the _ of body composition assessment <1% BF
- pros: accurate, based on assumptions
- cons: original reference body was based on a few cadavers, only one female
- can be difficult for individual who is hydrophobic
- can be expensive for all of the equipment
“gold standard”
- same principle as hydrostatic
- determine body volume differently
- body volume determined in a capsule
- accuracy, similar to hydrostatic
- expensive ($65K)
Bod Pod
_ principle/theory:
- percentage of body weight that is 70-75% at birth
- methods that determine total body water can in turn, predict body fat and lean mass
- tracers/dilution
- BIA
- TOBEC
hydrometry
Total body water measurement by dilution:
- tracer is distributed only in the _
- tracer is _ distributed in all anatomical water compartments
- rate of equilibration of the tracer is rapid
- neither the tracer nor the body of water is _ during the time of tracer equilibration
- body of water
- equally
- metabolized
Types of _:
- Tritium
- Deuterium
- Oxygen-18
- accuracy: can be as accurate as a precision of 1-5%
tracers
Tracers:
- Pros: does not require _
- Cons: can be _, does us radioactive isotopes (can be fearful for some)
- subject cooperation
- expensive ($5-100)
Bioelectrical Impedance and Total Body Electrical Conductivity:
- principle/theory:
- tissues high in water are _
- electrical current flows the path of _
- volume of tissues can be determined from measurements of combined resistances
- accuracy of BIA: 1-2% precision, 3.5-5% accuracy
- assumptions:
- assumes that the _ has uniform conductivity, is homogenous, a constant cross-sectional area, and known length
- no conduction in the “non conductive” components of the body
- highly conductive
- least resistance
- cylinder
- first used to asses the lean mass of hogs
- in 1985 commercial devices to measure body comp in animals, children and adults
- in 1994, took off the market
- can be influenced significantly by electrolytes
TOBEC
TOBEC:
- principle/theory:
- underlying principle is the _, conductivity of a tissue is dependent on its water content and free electrolyte concentration, temperature, and frequency of the current
- _ to the volume of the fat and the bone-free body mass
- accuracy: 2.5% body fat is considered marginally superior to BIA
- method: an electric current is induced into the body using an _ rather than a current using electrodes
- same as for BIA
- directly proportional
- electromagnetic field
Pros/Cons of all hydrometry
- pros:
- BIA: easy, little subject cooperation
- TOBEC: easy to use, little subject cooperation
- cons:
- BIA: _ can significantly alter results, as an electrode placement
- TOBEC: expensive and equipment is _ by manufacturer
- hydration levels
- no longer supported
challenges of hydrometry
- body is not cylinder, with uniform CSA
- smaller cylinder (arm) = _
- arm is 4% of weight
- leg is ~17%
- arm has 47% resistance, leg ~50%
- trunk is 46% of BW, little to no influence on resistance
- appropriate for _ studies
- most of the resistance
- epidemiologic
Whole body counting and neutron activation analysis:
- based on early whole body counters to count radiation exposure
- principle/theory:
- _ measurement of the body’s radioactivity. including naturally occurring potassium
- Three types of potassium in the body:
- 93.1% is 39K
- 6.9% is 41K
- 0.0118% is 40K
- isotope 40K is _
- TBK for average male is ~ 140g, average female ~ 100g
- in-vivo
- radioactive
Whole body counting and neutron activation analysis:
- assumptions/accuracy:
- while precision is very good, _ is not as good, 4-6% greater in the young
- Pros/cons
- Pros: easy, precise
- Cons: Expensive ($30,000-300,000)
accuracy
Dual energy X-ray absorptiometry (DXA)
- principle/theory:
- calculate the mineral content and then the _ can be measured with each pixel
- estimate fat, not adipose tissue (CT)
- calculate _ tissue and _ tissue
- pure fat
- lean, fat
Dual energy X-ray absorptiometry (DXA)
- assumptions:
- _ does not change body comp data (minimal)
- measurements not affected by anterior-posterior thickness of the body
- area of the body analyzed to determine _ and the degree to which the fat content of the area analyzed is associated with the fat content of the area that is not analyzed
- Accuracy:
- 2.5-3.5% SEE
- Pros/Cons
- Pros: easy to do, does not require subject cooperation
- Cons: expensive ($150,000)
- hydration levels
- body comp
CT Scan
- Pros: _
- Cons: radiation, expensive
accurate
Anthropometric: circumferences, skinfolds, stature
- can be applied to laboratory and field settings
- principle/ theory and assumptions:
- tissues included in the measurement are in the _, muscles are relaxed and soft tissues are normally hydrated
- the bigger it is, the _ the body fat
- accuracy: skinfolds
- technician and equation _, +/- 3.5% error
- Pros/Cons: skinfolds
- Pros:
- easy to perform, can test a large population, _
- Cons:
- depending on equation utilized, can have errors
- large technician error
- “standard” state
- greater
- dependent
- inexpensive
- developed in agricultural research
- product uses same wavelength for animals as humans
- accurate for animals, not accurate for humans
infared
- anorexia nervosa
- bulimia nervosa
- binge-eating
disordered eating
- psychotherapy
- nutritional counseling
- medical supervision
- athletic trainer/exercise physiologist
- did you know… 4/10 americans have either suffered or have known someone who has suffered from an eating disorder
treatment for disordered eating
Drive for thinness:
- 42% of _ grade girls want to be thinner
- 81% of _ are afraid of being fat
- 1st-3rd
- 10 year olds
Newer facts for drive for thinness
- average american woman is _ and weighs _
- the “ideal girl” (described by caucasian teenage girls) is _ and weighs _, and wears a size 5
- at age 13, 53% of american girls are “unhappy with their bodies”
- increases to 78% by the time girls reach age _
- 5’4”, 163lbs
- 5’7”, 110lbs
- 17
Facts about women and ideals:
- 1 in 40,000 women meet the requirements to be a fashion model
- average woman is a size _ (Marilyn Monroe)
- models 20 years ago weighted 8% less than average woman; today they weigh _
- if mannequins in shops were real, they would not menstrate
- 14
- 23% less
- Ana Carolina Reston: died 11/15/06 at age 21, weighing 88 lbs
- Luisel Ramos: died 8/26/06 at age 22, 98 lbs
- Eliana ramos (sister of Luisel): died 2/13/07 at age 18, 84 lbs
- Mariara Galvo Vierira: died 1/6/07 at age 24, 84 lbs
- Hila Elmalich: died 11/04/07 age 34, 60 lbs
Tragedy of modeling
- at risk: athlete (not necessarily competitive)
- controlling figure in her life (often male)
- strives for perfection
- physiologic vulnerability
female athlete triad
Energy Balance equation
- weight change =
total energy intake - total energy expenditure
Weight management: intervention strategies
- _: appetite, thermogenesis, resting metabolism
- _: food absorption
- _: food intake, physical activity
- drugs
- surgery
- behavior therapy
Control of food intake;
- control center is the _
- hunger center
- satiety center
hypothalamus
Resting energy expenditure:
- _ necessary to live, resting
- anything above is additional energy requirements
metabolic requirements
- most common treatment for excess weight
- consumption of diet is also important
- not “one size fits all” evidenced by twins study
- most regain weight after
caloric restriction
physical activity began during caloric restriction and maintained after resumption of previous caloric intake
Most effective for maintenance of weight loss
Greatest rates of overweight/obesity after _, people ate more typical “American diet”
- Prima indians
WWII
Chronology:
Ancel Keys, fat is bad, the Mediterranean diet is better (post-WWII)
- Naples
- poorer were heavier
- 2,400 kcals vs 3,800 kcals
- working-class women were overweight
1951
Chronology:
Prima Indians
- more than 1/2 of boys and girls obese
- widespread poverty
1954
Chronology:
Durbin, SA
- among Zulu 40% of women Obese
- numerous signs of malnutrition
- ~20% heavier and 4” shorter than men
1960
Chronology:
Nauru, South Pacific
- everyone past puberty is grossly overweight
1961
Chronology:
Trinidad, West Indies
- malnutrition and obesity serious problem
- ~ 1/3 of women obese
- caloric intake <2,000 kcal/day
1961-1963
Chronology:
Chile
- obesity: main nutrition problem of adults
- factory workers
- 35% males OB
- 39% female OB
- significant physical labor
1963
Chronology:
Joburg, SA
- Urban Bantu prisoners 60+ year olds
- 30% women OB
1964-1965
Chronology:
North Carolina
- 29% adult Cherokee on Qualla Reservation OB
1965
Chronology:
Ghana
- 25% women and 7% men OB
- 1/2 of all women in 40’s OB
1969
Chronology:
Lagos, Nigeria
- 5% men OB
- 30% women OB
- women: 55-65 year olds - OB
1970
Ketogenic Diet:
- _: 70% fat, 20% protein, 10% CHO
- _: SKD for 5 days, 2 days high CHO
- _: add CHO for workouts
- _: 60% fat, 35% protein, 5% CHO
- standard keto diet
- cyclical keto diet
- targeted keto diet
- high protein keto diet
- epilepsy
- cancer cachexia
- cancer with tumor metabolism drugs
- inflammatory diseases
- CAD
- diabetes
positives for keto diets
- can be dangerous
- loss of lean body mass
- associated with serious cardiac arrhythmias
- many people have died of cardiac arrest
- loss of hair
- thinning of skin
- coldness in the extremities
- gallbladder stones
- gout
- elevated cholesterol
very low calorie diets
- religious and/or health
- alternate day fasting
- 1 day/wk or 5 days every 5 week
- 25% of energy restriction: alternating days, SaMW
- time-restricted eating, 8-22 hrs
- often for weight loss
intermittent fasting
Intermittent fasting:
- hypothesized to influence _ via effects on:
- cicadian biology
- the gut microbiome
- modifiable lifestyle behaviors
- negative perturbations of these biological and physiological systems
- hostile _
- _ individuals to developing obesity, diabetes, cardiovascular disease, and cancer
- metabolic influence
- metabolic milieu
- predisposes
- diuretics
- impermeable clothing
- weight loss is due to this, but not fat loss
- usually re-hydrate after the loss
dehydration
- prolonged fasting
- gastric/bariatric bypass
- lipectomy (liposection)
medical procedures
- appetite suppressants
- thermogenic drugs
- orlistat (xenical & Alli): fat absorption in the gut 30% less
- 7-10# more than if diet alone
- Sexenda: slows gastric emptying
drugs to control weight
Behavior modification:
- focus on elimination of behavior that is associated with _ and _
- many theories of behavior change
- 30% of participants _ after one year and continue to lose
- poor eating, exercise habits
- maintain weight loss
Exercise:
- vigorous exercise _
- single session of exercise will result in little fat loss
- regular exercise training will lead to adaptations that increase with utilization of fat
- 1977: NIH OB & Wt control
- increase in _ leads to an increase in _
- stimulate appetite
- energy expenditure, energy consumption
- begin to utilize fats earlier in the exercise bout
- utilize more fats
- females utilize more fats more efficiently than males
exercise adaptations
- females are more efficient at _
- females store _
- females may store more from a similar meal of fat than a male would
- storing fat
- more fat
Fat metabolism:
- _ process and store lipids
- procedure a variety of _
- _: reduced or absent fat deposits
- insulin resistance
- Type II diabetes
- adipocytes
- hormones
- Lipoatrophy
Leptin gender differences
greater in females
Best activity for weight loss
- 1 mile = ~ 100 kcal
- whether walk/run the mile
HITT
- should be small
- should become part of your lifestyle
- ~21 days to make a habit
- eat at the same time everyday
reasonable changes
- meal planning
- physical activity
- behavior therapy
- lifestyle therapy
- pharmacotherapy
- weight reduction surgery
- weight maintenance plan
weight loss strategies
- eat a colorful diet
- close to the ground
- if it’s white, it’s probably not right
recommendations
_ is more important than a “diet” or weight loss
- better long-term outcomes and long-term health
- if it took 5 years to gain weight, unlikely to lose it in 3 months
weight maintenance
Altitude:
< 12,000 ft = _
12,000-18,000 = _
> 20,000 ft = _
- moderate
- high
- very high
Stress at altitude:
- The 4 “H”s
- hypoxia
- hypothermia
- hypoglycemia
- hypohydration
Stress at altitude:
- additionally
- suppressed _ and _
immune system, emotional state
Stress of altitude:
- O2% at sea level = 21%
- O2% at 22,000 ft = 21%
- decreased PO2 results in _
hypoxia
Adaption to the new natural environment
acclimatization
Acclimatization:
- respiratory
- hyperventilation
- body fluids become more base as a result of reduction in CO2 with hyperventilation
- cardiac
- increased heart rate at rest and a submax work = increased cardiac output
- stroke volume remains the same or decreases
- max VO2 remains the same
immediate
Acclimatization:
- respiratory
- hyperventilation
- excretion of base via kidneys and concomitant reduction in alkaline reserve
- cardiac
- increased submax heart rate
- submax cardiac output falls
- stroke volume decreases (Starling’s law)
- max VO2 decreases (decreased max HR and stroke volume)
longer term (days to weeks)
Acclimatization:
- decreased plasma volume
- increased plasma volume
- increased # of RBCs
- possible increase in capillary density
- increased 2,3 DPG
- increased mitochondrial density
- increased aerobic enzymes in muscle
hematological response
Acclimatization:
- nor-epinephrine
- increased 7 days and then stabilizes
- epinephrine
- shows little to no increase
- regulates HR, BP, SV, vascular resistance, and substrate use
catecholamine response
Acclimatization (Acid Base Balance):
- _ leads to a decrease in CO2 thus increasing pH of all bodily fluids
- this blunts respiratory control
- body begins to excrete base through _ to normalize pH
- this increases respiratory sensitivity and allows for greater hyperventilation
- this decrease in “base” creates a loss of the _ reserve inhibiting the body’s buffering ability
- this is made up for by a decrease in _ and a reduction in _
- hyperventilation
- renal tubules
- absolute alkaline
- intercellular ADP, epinephrine output
Acclimatization schedule:
- rapid ascent 0-7,500 ft _ to adjust
- then _ per 2,000 ft up to 15,000 ft
- 2 weeks
- 1 week
Acclimatization schedule:
climb to camp altitude
- active acclimatization
- move to next camp
- repeat as necessary
- summit
- get outta dodge
stage ascent
all are exacerbated by:
- speed of ascent
- altitude
- health of individual
- general susceptibility of individual
altitude related illness
Altitude related illness:
- _ symptoms:
- diminished exercise capacity
- shortness of breath
- elevated HR
- Cheyne-strokes (irregular nighttime breathing)
slow ascent
Altitude related illness:
- _ symptoms:
- most common altitude disorder
- can appear within 2 hrs of ascent
- headache
- insomina
- irritability
- weakness
- vomiting
- tachycardia
- breathing problems
rapid ascent - acute mountain sickness (AMS)
Altitude related illness:
- Rapid ascent
- 12-96 hrs of ascent
- can be treated on site but reduction in elevation is best
high altitude pulmonary edema (HAPE)
Altitude related illness:
- Rapid ascent:
- results from vasodilation, increased capillary hydrostatic pressure
- must descend to accurately diagnose and treat
high altitude cerebral edema (HACE)
Altitude related illness:
- Rapid ascent:
- can occur after months or years at altitude
- polycythemia
- genetically linked EPO response to stress
chronic mountain sickness (CMS)
Altitude related illness:
- Rapid ascent:
- all climbers experience over 21,000 ft
- hemorrhage of the macula results in vision loss
- eye surgery
high altitude retinal hemorrhage (HARH)
Body composition and nutrition:
- _ and _ occur at altitude
- depressed appetite
- dehydration
- increased BMR
- increased energy output
muscle atrophy and weight loss
Body composition and nutrition at altitude:
- increased respirations = dehydration
- low relative humidity at altitude
- greater loss in fecal matter
- less adsorption in gut
- inadequate fluid intake
- lose desire
- difficult to obtain
hypohydration
Physical performance at altitude:
- max strength is _
- capacity for repeated contractions is progressively impaired
- endurance is _ but improves with _
- decrease _
- unaffected
- initially decreased, acclimatization
- motor skills
Mental performance at altitude:
- decreased _ (Ex: “where did I park my car?”)
- mental activity (Ex: Let’s see it’s “I” before “E” except after no wait it’s …)
- _
- brain blood flow _
- short term memory
- judgment/decision making
- not impacted
Altitude:
As we gain altitude the _ drops resulting in inadequate hemoglobin saturation and a decrease in _
- PO2
- aerobic activities
Altitude:
ability to perform _ physical activity is not affected
high intensity short duration (sprint)
Altitude:
reduced PO2 results in physiologic responses that improve _
altitude tolerance
Altitude:
_ and increased submax cardiac output via elevated HR and the primary _ responses to altitude
- hyperventilation
- immediate
Altitude:
- medical problems may emerge as a result to _ to altitude
- _, _, and _ are the most common conditions
- travel
- AMS, HAPE, and HACE
Altitude:
_ entails:
- reestablishment of acid-base balance
- increased synthesis of RBC and hemoglobin
- improved local circulation and cellular metabolism
acclimatization
Altitude:
Rate of acclimatization depends on the _
- major adjustments takes about _ but may require 4-6 weeks at higher altitude
- elevation
- 2 weeks
Altitude:
acclimatization does not fully compensate for the stress of altitude, as a result, _ remains depressed
VO2 max
Altitude:
training at altitude provides _ benefit to sea-level performance than equivalent sea-level training
no more
Chilean miners:
- trapped for 69 days at 2,050 ft below sea level
- pressure increases _ for every _
- _ below sea level
- 1 atmosphere (760 mm Hg), 10m (33 ft)
- 62.1 atmospheres
Effects of exposure to high pressure
- _
- dangers stem from changes in gas volumes within enclosed spaces and increased solubility of gases
- think about soda bottle opening after flight
hyperbia
- tissue injury caused by changing pressure
- human body had a limited ability to distend and compress
- trauma comes from exceeding those limits
- humans, sea otters and sea lions as diving mammals is unnatural - need continuous air
barotrauma
- Boyle’s law applies: volume of gas decreases or increases as diver goes up and down
- pressure is not allowed to equalize with air from outside the space
barotrauma
- gases like O2, CO2, CO, N2, and He can be dangerous under certain conditions
- need to manage toxicity with depth and length of dive
gas toxicity
CO: dangerous to all life forms
- compressed air may have been contaminated by exhaust fumes
- danger due to high affinity for _: 240 more times the affinity than O2
- problem is compounded if diver is a _ or exposed to air pollution
- hemoglobin
- smoker
- O2 at higher pressure is toxic to all life forms - depends on its concentration and length of exposure
- _ speeds up development of toxicity
- principal sites of O2 toxicity and lungs and CNS
O2 toxicity
- physical exercise
- substernal distress with soreness in chest
- airway resistance on inspiration
- histological changes in alveoli
- pulmonary edema
- flushing of the face
- couch that starts out dry and gets wet
- decreased surfactant
pulmonary symptoms of toxicity
- nausea
- contraction of the field of vision
- convulsions
- lack of sphincter control
- unconsciousness
- death
- can also cause arrhythmias
- mechanism that causes it is unknown
CNS symptoms
CNS symptoms
- _ may interfere with CO2 transport
- hemoglobin doesn’t desaturate thus isn’t available for O2 transport
- _ vasodilates cerebral blood vessels causing _ and increased PO2 in the brain
- cell function may also be disrupted as well as neural transmission in CNS
- hyperbaric O2
- increased CO2, acidosis
- most common in closed-circuit scuba systems and hose-supplied helmets
- inadequate respiratory exchange leads to _ with heavy exercise at high pressures
- happens if diver tries to suppress their _ in order to conserve air, CO2 builds up
CO2 toxicity
- hypercapnia
- ventilation
- uncomfortable breathing
- mental deterioration
- violent respiratory distress
- unconsciousness
- convulsions
symptoms of CO2 toxicity
- some gases exert a narcotic or anesthetic effect at high pressure
- effects depend on partial pressure of the gas and its solubility in the body’s tissue and fluids
nitrogen narcosis
- nitrogen can cause conditions: nitrogen narcosis ~30m (100ft)
- progression of symptoms:
- euphoria
- impaired performance
- weakness
- drowsiness
- unconsciousness
- caused by interference in the _ across the neural synapses
- this is why the use of compressed air is limited to _
- replace nitrogen with helium
- transfer of signals
- ~50m (165 ft)
Nitrogen narcosis:
- below 150m (500ft) can cause neuromuscular disorder called _: tremors, vertigo, and nausea
- slowing compression rate during dive and adding nitrogen to O2 mixture and help prevent this
- nitrogen narcosis is a limiting factor during _
- almost impossible to avoid in commercial dives
- slows down information processing in the brain, but does not distort perception
- _ activity level can help
- high-pressure nervous syndrome (HPVS)
- deep dives
- slowing down
- caused by a nitrogen bubble formation in the tissue due to too rapid of an assault
- symptoms include:
- itchy skins
- fatigue
- pain in the muscles, joints and bones
- persisting perspiring, nausea
decompression sickness (the bends)
The bends:
- more serious ones include respiratory distress, ataxia (loss of muscle), vascular obstruction, paralysis, unconsciousness, and death
- called _ when it affects the lungs and the _ when it affects the CNS
- symptoms appear about _ after surfacing but can occur either immediately or _
- “the chokes”
- “the staggers”
- 1 hour
- up to 12 hours post
The bends:
- if _ is too rapid, N2 returns to gaseous state, and bubbles form in blood and tissues
- decompression tables help divers figure absorption levels
- decompression time increases with _ and _ of dives
- must also consider body fat, age, physical condition, gas mixtures, alt of dive
- decompression
- depth, length
- studies are conducted in _ or underwater
- chamber provides opportunity to isolate variables like partial pressures, temperature, and gas mixtures
- can stimulate ocean dives too, to help understand differences
hyperbaric exercise
- hyperbaric chamber
- expensive equipment and facility
- technically exacting
- open water measurements are complex because of restraints of aqueous environment
biological measurement difficulties in hyperbaric environment
- increased air density
- cold
- decreased efficiency
- CO2 retention
- inert gas narcosis
factors adding difficulty to exercise underwater
Ve may be limiting factors:
- maximal voluntary Ve _ with depth
- results in progressively smaller difference between exercise Ve and max capacity
- higher densities of air _ in scuba equipment and airways, causes _
- decreases
- increases flow resistance
- hyperventilation
Ventilation:
- _ leads to loss of CO2. which leads to increased _
- ability to increase _ is limited
- after reaching max flow rate, further effort results in
- work to breath
- expiratory flow rate
- partial airway collapse
- increased energy cost to breath
- maintaining body temperature
- movement in higher hydrostatic pressures
O2 consumption increases with submax work with increasing depth
Experienced divers can achieve _ of their land-measured max O2 but work efficiently is _
- max capacity is dictated by _ attained before reaching critical PCO2
– swimming angle and drag produced by scuba equipment greatly affects _ and individual differences in swimming efficiency
- ~91%, reduced
- tolerance to high levels of CO2 and % of max O2 consumption
- energy cost of underwater work
- HR decreases as water temperature decreases and pressure increases
- divers should not use land-measured relationships between HR and O2 consumption, dangerous
- HR can be used to estimate energy cost in diving only when HR/VO2 relationships is known for a certain diver at a certain depth
diving bradycardia
Exercise in the cold & hot:
- _: at mercy of the elements
- _: can function independently of the environment
- ability to maintain constant temperature
- poikilotherms
- homeotherms
Exercise in the cold & hot:
- temperature always _ from hot to cold
- _: temperature differences from one point to another lead to movement of heat
- equilibrates
- thermal gradients
Normal body temperature: _
- during exercise can increase to _ with no ill effects
- core temperature: temp of the _ - temperature regulatory of the body
- 36.5-37.5 degrees C
- 40 degrees C
- hypothalamus
- metabolism
- shivering
- nonshivering thermogenesis
- metabolic rate
- heat loss
temperature regulation
Metabolism:
- heat is produced naturally during normal metabolic reactions
- most reactions lose ~75% of _
- at BMR heat loss is _
- BMR is proportional to 3/4 _ (surface rule)
- energy as heat
- ~ 100 kcal/hr
- power of body weight
- main mechanism for increasing heat during negative heat balance
- involuntary muscle contraction
shivering
Shivering:
- maximum shivering can increase body’s heat production by _
- pre-shivering tone can increase heat production _
- an effective way to increase body temperature because _ by the muscles, and most of the energy is expended as heat
- 5x
- 50-100%
- no work
Shivering:
- increases Q by increasing SV via increased _
- _: glycogen depletion, hypoglycemia, fatigue (Ex: hypoxia, drugs - alcohol & barbiturates)
- venous return
- limits
- increased thyroxin secretion (thyroid) and catecholamine secretion (adrenals) increase metabolic rate
- thyroxin increases the rate of all cells
- Cats., especially norepi. release FFA, increasing metabolic rate
nonshivering thermogenesis
Metabolic Rate (Q10 and food):
- _ is rate of physiologic process at a particular temperature to the rate as a temperature 10 degrees C lower
- increased metabolic rate can be _ (dangerous)
- Q10
- self-perpetuating
Metabolic Rate (Q10 and food):
- at high temperatures, _ loses ability to cool the body
- Rate of temperature increases _ at higher temperatures
- metabolic rate _ following food intake, especially proteins
- hypothalamus
- faster
- temporarily increases
- radiation
- conduction
- convection
- evaporation
heat loss
Radiation:
- loss or gain in the form of _
- at rest, in a comfortable environment, radiation accounts for 60% of _
- varies with body position and clothes
- human skin, regardless of color, absorbs _ of radiant energy that strikes it
- electromagnetic waves
- total heat loss
- ~97%
Conduction:
- transfer of heat from a _ to an _
- or, heat transfer within an organism down a _
- ~3% of _ at room temperature occurs this way
- body, object
- thermal gradient
- total heat loss
Convection:
- conduction of heat to _
- amounts to ~12% of _ at room temperature
- air or water
- all heat lost
- heat is conducted to water or air, moves so that other molecules can be heated
- greater in the wind (air movement)
- wind chill effect
- can also occur in the circulatory system
- heat moves with the blood from the _
- as skin temperature increases, _ to environment increases
- rate is affected by blood flow and temperature gradient (core/periphery)
Convection
- core to the periphery
- heat loss
Evaporation:
- _ of heat is lost this way in a comfortable environment
- Quantity of heat absorbed by _ as it evaporates: latent heat of vaporization
- Body loses 0.58 kcal/gm H2O
- only means of cooling at high _
- critical for _
- ~25%
- sweat
- environmental temperatures
- exercise
Evaporation:
- if body cannot lose heat this way, body temperature _
- sweat is only effective if it _
- _: evaporation reduced or prevented
- effective evaporation also hampered by little air movement
- increases rapidly
- evaporates
- high humidity
Evaporation:
- women have a lower sweating capacity than men do
- process occurs by _: ventilation, diffusion through skin, does not include sweat, urine and feces
- sweat rates are at 0 when temperature is _
- sweating and insensible water loss
- low
- temperature regulatory center
- set-point it tries to keep
- sweating normally occurs at 37 degrees C
- set-point can change in response to dehydration, starvation, and fever
- responds to heat primarily through _ in the preoptic area of anterior portion
Hypothalamus and temperature regulation
- heat-sensitivity neurons
Hypothalamus and temperature regulation:
- more _ than _ receptors in the skin
- _ transmit impulses to the spinal cord, to hypothalamus, initiates response
- _ stimulates the sweat glands, evaporates heat loss
- “hunting reflex” primarily in _
- cold, heat
- thermoregulators
- anterior hypothalamus
- hands and feet
- clothing
- oxygen consumption
- ventilation
- heart
- muscle strength
- metabolic changes
exercise in the cold
Exercise in the cold:
- oxygen consumption
- maximum uptake is _ by the cold
- _ increases in the cold
- unaffected
- submax VO2
Exercise in the cold:
- ventilation
- _ in the cold, particularly if exposure is sudden
- abrupt exposure can lead to _
- increases
- gasping reflex
Exercise in the cold:
- Heart
- changes in cardiac performance _ in men
- incidence of arrhythmias _ in cold
- more common
- increase
Exercise in the cold:
- muscle strength
- strength _ with lower muscle temperature
decreases
Exercise in the cold:
- Metabolic changes
- increase use of _ as substrate
- _: glycogen depletes faster
- _: depletion is independent of temperature
- _: hypoglycemia, suppresses shivering, core temperature drops, lactate higher
- fat metabolism suppressed, even through cat. response is higher
- CHO
- light exercise
- max exercise
- prolonged exposure to cold
- _: physiologic compensation to environmental stress over time
- _: lessening of the sensation associated with an environment
- acclimatize
- habituation
Acclimatization and habituation to cold:
- shivering threshold
- _ test of acclimatization
-_ maintain heat production with less shivering, more _
- first
- cold-acclimatized people, nonshivering thermogenesis
Acclimatization:
- _ and _ temperature
- _ test for acclimatization
- acclimatized: maintain almost normal temperature
- habituation also plays a role
- hand, feet
- second
Acclimatization:
- ability to _ in the cold
- _ test for acclimatization
- seems to depend on extent of nonshivering thermogenesis induced by increased secretion of norepi
- sleep
- third and final
- depresses the CNS. lose ability to shiver, sleepiness, coma, death
- lower temperature: lower cellular metabolic rate, further lowering temperature
- profound effects on the CV system
- central BV decreases; plasma sequestration, inadequate fluid intake, cold diuresis
hypothermia
- cold exposure
- lack of protective clothing
- leanness
- inadequate fluid intake
- high wind chill
- use of alcohol and/or drugs
- use of snow to relieve thirst
- glycogen depletion
hypothermia risk factors
- caused by ice crystal formation within the tissue
- occurs in exposed skin
- can lead to tissue death
frostbite
plasma volume _ during exercise in the heat
- becomes acute as _
- decreases of plasma volume is made worse by loss of _
- may not be enough blood to adequately perfuse all areas during exercise in the heat
- decreases
- intensity increases
- body fluids through sweating
Plasma volume:
- central blood volume may decrease and cause a decrease in _
- results in increased _ in attempt to compensate for lower SV
- submax heart rate increases also
- at max levels, skin vessels vasoconstrict to help maintain _ and _
- cardiac filling pressure
- heart rate
- blood pressure and Q
Plasma volume:
- _ response on heat transfer
- _ regulation takes precedence over temperature regulation in this case
- VO2 max is _ in the heat unless the person was experiencing thermal imbalance before beginning the exercise
- negative
- circulatory
- not impaired
Sweating response:
- primary means of _ during exercise (evaporation)
- in heat, sweating is very important because the body tends to _ rather than lose heat by radiation, conduction, and convection
- during exercise, sweating is related more to _ than environmental temperature
- heat dissipation
- gain
- intensity
Acclimatization to heat:
- _ of heat exposure results in
- lower heart rate
- lower core temperature
- lower RPE
- lower skin temperature at rest and during exercise
first 2 weeks
Acclimatization to heat:
- primary _ are increased
- peripheral heat conductance
- plasma volume
- sweating
- _ core temperature at onset of sweating, and improved distribution of sweat over the skin
- physiological adjustments
- decreased
Cardiovascular adaptations:
- acclimatization induces a _ increase in plasma volume if acclimatization is done with exercise training
- increased plasma volume helps to maintain _, _, and _
- also increases in vasopressin, renin, and aldosterone in the early days
- 3-27%
- SV, central blood volume, and sweating capacity
Cardiovascular adaptations:
- blood flow to the skin _
- decreased skin blood flow helps to maintain _ , which is vital for maintains BP, SV, and muscle blood flow during exercise
- _ is lower during exercise
- decrease in skin blood flow is accompanied by a _ in sweating and evaporative cooling capacity
- decreases
- central blood volume
- core temperature
- large increase
- acclimatization increases _ almost 3X, from ~1.5 L/hr to 4 L/hr
- accompanied by a _ distribution of sweating
- sweat losses of sodium chloride decrease because of increased secretion of _
- sweating response
- more even
- aldosterone
- includes dehydration, heat cramps, heat exhaustion, heat syncope, and heat stroke
- hypothermia is caused by an imbalance between heat gain and heat loss
thermal distress
Optimizing hydration:
- approximately 7-20 ounces 2-3 hours before activity
- consume another 7-10 ounces after the warm-up (10-15 minutes before exercise)
pre-exercise
Optimizing hydration:
- approximately 28-40 ounces every hour of exercise (7-10 ounces every 10-15 minutes)
- rapidly replace lost fluids ( sweat and urine) within 2 hours after activity to enhance recovery by drinking 20-24 ounces for every pound of body weight lost through sweating
during exercise
- can decrease sweat rate, plasma volume, Q, Vo2 max, work capacity, muscle strength, and liver glycogen
Dehydration
Dehydration:
- loss of fluid from the body
- at fluid deficit of _ of BW, symptoms include discomfort and alternating states of lethargy and nervousness
- _is extremely dangerous
- 5%
- level >7%
Dehydration:
- at _, ability to walk is impaired and is accompanied by discoordination and spasticity
- as _is neared, the person experiences delirium, shriveled skin, along with decreased urine volume, loss of ability to swallow food, and difficulty swallowing water
- _ the skin bleeds and cracks
- levels >10%
- 15%
- > 20%
Dehydration:
- _ does not keep up with fluid requirements
- physical fitness helps prevent this
- during prolonged exercise, can develop hypothermia, caused by excessive _ in the sweat without adequate replacement
- thirst
- sodium loss
Heat cramps:
- it occurs in people who have exercised and sweated heavily
- often the individual is _ and _
- _ and _ replacement, rest, some may say magnesium helps
- conditioned and acclimatized
- fluid and electrolyte
- characterized by involuntary cramping and spasm in muscle groups used during exercise
Heat cramps
Heat cramps:
- electrical activity plays a role
- _ and/or _ are the background for cramps
- mild dehydration
- low electrolytes
rapid, weak pulse, hypotension, faintness, profuse sweating, and psychological disorientation
heat exhaustion
Heat exhaustion:
- results from acute _ and inability of the circulation to compensate for the concurrent _ in the skin and the active working muscles
- plasma volume loss
- vasodilation
- have person lie down in a cool area
- administer fluids
- rest and drink plenty of fluids for next 24 hours
- not allowed to participate for rest of the day
treatment of heat exhaustion
- related to heat exhaustion. but can occur without major sweat loss
- typically, it occurs after exercise when the individual stops moving and blood pools
- can occur secondary to heat exhaustion or independently
Heat syncope
- related to heat exhaustion. but can occur without major sweat loss
- typically, it occurs after exercise when the individual stops moving and blood pools
- can occur secondary to heat exhaustion or independently
Heat syncope
- failure of hypothalamic temperature regulatory center: represents a major medical emergency
- principally caused by failure of the temperature regulatory center in the hypothalamus, which causes failure of the body’s heat loss mechanisms
heat stroke
- characterized by a:
- high core temperature,
- hot, dry skin, and
- extreme CNS dysfunction
- associated with increases in plasma norepinephrine, epi, and endotoxin levels that have been associated with vascular collapse
heat stroke
Heat stroke:
- risk is greatest in _ temperatures, _, _ time of day, and on days with _
- high
- humidity
- hottest
little wind
- cool person with tepid water
- ice packs on groin, neck, and axilla
- send to hospital ASAP
treatment of heat stroke
Heat stroke prevention:
- ensure athletes are well-conditioned
- avoid _
- be aware of _: thirst, fatigue, lethargy, and visual disturbances
- athletes should not train harder than normal intensity
- should not compete if have an illness accompanied by a _
- overheating
- early symptoms of heat stress
- fever
Heat stroke prevention:
- schedule practice during the _ times of the day
- modify or cancel sessions when the wet bulb temperature is _ or greater
- plan regular fluid breaks
- supply a drink that is cold and contains some _ and _
- cooler
- 25.5 degrees C
- CHO and electrolytes
- hyperhydrate before activity
- fluid replacement should be encouraged during the early stages of practice and competition
Heat stroke prevention
Heat stroke prevention
- athletes should be weighed every day before and after practice
- if a 2-3% decrease in weight, should _
- if 4-6%, should _
- if 7% loss, _
- consume more fluid
- decreases activity levels
- consult a physician
- striated muscle breakdown
- myoglobin excretion is increased
- cola-colored urine
- myoglobin is cleared by the kidneys
- kidneys shut down, especially with heat
Rhabdomyolysis
can lead to:
- acute renal failure
- sudden cardiac death- athletes
- acuter compartment syndrome
Rhabdomyolysis
Rhabdomyolysis:
- occurs with _
- _
- may be a _, latent metabolic disorder
- diuretics contribute to this
- CHO as well, but a rare possibility
- deconditioned
- previous _
- excessive exercise
- rare
- predisposition
- heat injury
Rhabdomyolysis causes:
- _
- multiple trauma; crash injury
- surgery
- comma
- immobilization
- _
- exertion
- health illness
- seizures
- metabolic myopathies
- malignant hyperthermia
- Traumatic
- exertional
Rhabdomyolysis causes:
- _
- _
- ETOH
- Drugs- statins, OTC, illegal
- infection
- electrolytes
- nontraumatic
- nonexterional
