Exam 3 review slides Flashcards
temperature homeostasis
balance between heat gain and heat loss in order to maintain core temperature
normal core temp, low temp, high temp
normal: 37C
low temp: 34C (impaired metabolism and arrhythmias)
high temp: 45*C (protein and enzyme breakdown)
involuntary heat production
- shivering (5x increase)
- action of hormones (thyroxine and catecholamines)
4 ways to dissipate heat
- radiation
- convection
- conduction
- evaporation
changes in humididty result in — in vapor pressure
increases
skin vapor pressure
32 mmHg (the greater the gradient or difference is the greater heat loss)
POAH response to increase in core temp
- cutaneous vasodilation, allowing increased heat loss
- stimulation of sweat glands for evaporative heat loss
POAH response to decrease in core temperature
- shivering and increased norepinephrine release
- decreased skin blood flow via vasoconstriction
exercise intensity and heat production relationship
- positive linear relationship
- heat loss also increases in exercise however it does not mitigate the gains in heat production
Heat index
relative humidity added to air temperature, measure of how hot it feels
physiological concerns with exercising in the heat
- high humidity impairs evaporative heat loss resulting in higher core temp
- increased sweat rate results in higher risk of dehydration
percentage loss of body weight via fluid loss can lead to exercise performance impairment
1-2% body weight loss via sweat
ways to combat dehydration
- increase fluid intake before, during, and after exercise (consume 150-300 ml fluid every 15-20 min)
- consume electrolyte drinks to maintain electrolyte balance
as temperature and humidity goes up…
the body relies on evaporative heat loss more as convective and radiative heat loss become methods for heat gain
most beneficial techniques to mitigate heat gain in hot environments
- cold water immersion
- cooling ice vest
- cooling packs and towels
- ingestion of cold drinks
acclimation
rapid adaptation (days to weeks) to environmnetal change
acclimatization
adaptation over a long time period (weeks to months)
sex and age differences in thermoregulation
- little differences
- only due to deconditioning
cardiovascular dysfunction and impaired exercise performance
- reduced stroke volume
- decreased muscle blood flow
- decreased cardiac output during high-intensity exercise
accelerated muscle fatigue and impaired exercise performance
- muscle glycogen depletion
- decreased muscle pH
- increased radical production
central nervous system dysfunction and impaired exercise performance
- decreased motivation
- reduced voluntary activation of motor units
acclimation and inactivity
-acclimation is lost within days of inactivity or no heat exposure
-significant decline in 7 days, complete loss in 28 days
how to adapt to heat
- repeat bouts of exercise in hot environments
physiological adaptations during heat acclimation (5)
-10-12% increase in plasma volume to maintain blood volume, stroke volume, and sweating capacity
- earlier onset of sweating and higher sweat rate
- reduced skin blood flow
- reduced sodium chloride loss in sweat, reduced risk of electrolyte disturbance
- reduced risk of heat injury due to the synthesis of heat shock proteins
Adapting to heat and its impact on HR and core temp
- decreased HR with acclimation due to stroke volume maintenance and improved ability to mitigate heat gain
exercise in cool for heat acclimation
it works but less than training in the heat
partial pressure
- % of O2, CO2, and N2 in the air is same
- there is lower partial pressure of O2, CO2, and N2 at higher altitudes
hypoxia
low partial pressure of O2 (at altitude)
Normoxia
normal PO2 (sea level)
Hyperoxia
high PO2 (below sea level) (artificial?)
Altitude and short term anaerobic performance
- lower PO2 has no effect on performance
- lower air resistance may improve performance depending on event (long jump)
altitude and long term aerobic performance
lower PO2 results in poorer aerobic performance as it is dependent on oxygen delivery to muscle
altitude and VO2 max
- decreased VO2 max at higher altitude due to lower oxygen extraction
- decreased maximal cardiac output at altitude
Altitude, submax workload, HR, ventilation
- higher HR due to reduction in oxygen content in blood
- increases in ventilation due to reduction of O2 molecules per liter of air
Process of altitude acclimation
- kidneys produce erythropoietin (EPO) in response to decreased blood oxygen
- EPO in circulation stimulates increase in red blood cells
- increased red blood cells increases oxygen binding and blood oxygen content
- blood oxygen content increases toward sea levels as a result
Does training at altitude increase VO2 max?
- some athletes report gains in VO2 max while others do not
- may be due to different training status or detraining effect as exercise intensity is reduced at altitude
Live High, Train Low theory
- living at high altitudes stimulates an increase in RBC, while still being able to train at high intensity at training sea level results in no detraining effect observed
- must have prolonged exposure to moderate altitude or repeated shorter exposure to high altitude
- (The reverse aims to reduce the negative effects of prolonged altitude exposure; however, it results in little to no change in RBC concentration. VO2 max improvements without RBC increase have been shown due to increased mitochondrial function and buffering capacity however, it is highly debated)
lactate paradox
- at high altitude HR, lactate, and ventilation increases occur
- with acclimation, lactate is reduced due to low levels of plasma epinephrine or muscle adaptations
possible health events with hyperthermia (4)
- heat syncope (headache nausea)
- heat cramps (muscle cramping)
- heat exhaustion (profuse sweating, clammy hands, shallow breathing)
- heat stroke (lack of sweating, flushed skin color, labored breathing, unconscious)
Factors related to heat injury
- Fitness = higher fitness level associated with lower heat injury risk due to higher sweat rates and heat tolerance
- Acclimatization = increases in plasma volume and sweat capabilities, lower HR and body temp response, increases VO2 and CO during hot exercise, best protection against heat injury
- Environmental temperature = convection and radiation heat loss dependent on skin to air temperature gradient
- Hydration = dehydration effect can speed up fatigue and heat injury onset (loss of plasma volume, SV, and CO)
- Clothing = materials can impair evaporative and convective heat loss as well as trap heat at the skin decreasing core-to-skin temperature gradient
- Humidity (water vapor pressure) = evaporative heat loss is dependent on gradient between skin and air and increased humidity decreases that gradient reducing evaporation heat loss
- Metabolic rate = core temperature is proportional to work rate meaning that heat produced will be dependent on how hard the body is working
- Wind = increases both evaporative and convective heat loss due to more airflow over skin
ways for athletes to avoid heat-related problems
- emphasize pre-season conditioning as well as acclimation periods as increases in fitness will improve heat tolerance
-frequent water stops
-schedule events for cooler parts of the day and seasons of the year
risk of heat stress dependent on
- wet bulb globe temperature
- includes measurements of dry bulb temp (air temp in shade), wet bulb temp ( index of ability of evaporative heat loss), and black globe temp (the radiative heat gain in direct sunlight
overload
system is exercised at level beyond what is normally
specificity
training effect dependent on training type, differences in muscles fibers recruited and energy systems used
reversibility
gains and adaptations are lost when overload stimuli is removed
VO2 max and genetics
50% of VO2 max is determined by genetics
exercise to increase VO2 max
- prolonged dynamic exercise at 50-70% or higher VO2 max
- could increase by 15-20%
VO2 max improvements following training
- increases in SV and a-vo2 difference
- increased mitochondria, capillary density, blood flow results in greater oxygen saturation
- short duration training results in SV improvements, long duration training results in greater improvements
endurance training adaptations of fiber type and capillarity
- fast to slow shift in muscle fiber types
- reduction in fast myosin
- increase in slow myosin as well as increased capillarity
- results in greater oxygen diffusion/removal of waste products
endurance training adaptations of mitochondrial density
- Increased mitochondrial density
- Increase # of ADP transporters in mitochondrial membrane
- Improves efficiency of ATP production
- Results in lower O2 deficit at onset of exercise
- Same VO2 achieved at lower ADP levels
- Quicker rise in oxygen uptake
- Results in decreased metabolic strain and lowers lactate production and PC utilization
elements of strength training
- muscle strength
- muscle endurance
-muscular power
hypertrophy
- enlargement of both type i and type ii fibers, greater enlargement of type ii
- attributed to increases in myofibrillar proteins, number of cross bridges, ability to generate force
hyperplasia
- theory that one can increase muscle fiber number by splitting a singular fiber
- limited human research on this
- can be achieved with steroids
“early gainz” in strength program
- neural adaptations responsible for early gains in strength (initial 8-20 weeks)
- increased ability to recruit motor units, altered motor unit firing rate, enhanced motor unity synchronixation
strength training and antioxidant
- strength training improves antioxidant capability
- increasing antioxidant enzyme activity
- decreasing free radical/oxidative stress
- similar to endurance training adaptations
concurent endurance and resistance training
-the increases in AMPK following endurance training signal an increase in TSC1 and TSC2
- this can inhibit the mTOR activation, inhibit promotion of protein synthesis
- shift in cellular priorities that favors energy efficiency and mitochondrial biogenesis over muscle hypertrophy
three major principles of training
overload, specificity, reversibility
genetics plays a big role in
- Anaerobic
- Primary reason is the skeletal muscle fiber type that is best suited for anaerobic performance (i.e., fast fibers, type IIx)
determined early in development - Relative percentage of muscle fiber types does not vary widely over the lifetime
Warm up
Increases CO and BF to muscle
- Increases muscle temp and enzyme activity
- Might help reduce risk of muscle injury
stretching
-Stretching will improve flexibility
-Likely does not prevent injury
-Static stretching improves flexibility the most
-No prevention of DOMS (5 studies were done)
injury
-mainly due to overtraining
- from short-term high intensity or prolonged low intensity
% to increase exercise intensity by per week
10%
types of training
- High intensity interval training (HIIT)
- Long slow distance training
- High-intensity continuous training
long slow distance training
- Low intensity exercise
- Working 50-65% VO2max or 60-70% HRmax
- Popular means of training in 1970s
strength training exercises
isometric, dynamic, isokinetic
best method to improve VO2 max and lactate threshold
- High intensity continuous exercise
- Although the exercise intensity that promotes the greatest improvement in VO2 max may vary from athlete to athlete
- Discussed that exercise intensities between 80-100% VO2 max are optimal for improving VO2max
- Or training slighty above lactate threshold
types of strength training adaptations
-increased force production
- increased muscle mass
results of strength training adaptaiton
hypertrophy and hyperplasia
- hypertrophy is responsible for muscle growth
concurrent training
- Combined strength and endurance training may result in lower gains in strength than strength training alone.
- Strength and endurance training should be done on alternate days for optimal strength gains
- If you need maximal strength, you should not do concurrent training.
amenorrhea
- cessation of menstruation
- 12-69% of female athletes experience
- due to training amount, psychological stress, body comp (low body fat)
dysmenorrhea
- painful menstruation
major cause of osteoporosis (bone mineral disorder)
- estrogen deficiency due to amenorrhea
- inadequate calcium intake from eating disorders
- exercise cannot completely reverse bone loss
female knee injuries
more prone due to:
- dynamic neuromuscular imbalance
- fluctuation in hormones during menstrual cycle (more injury during ovulation)
- knee anatomy (larger Q angle at hips)
VO2 max in kids vs adults
- there is no risk of permanent cardiovascular damage, VO2 max improvements are similar in children and adults
benefits of training to children
- optimize growth
- promote muscular strength
- increase bone density
training concerns for children
- articular cartilage, epiphyseal growth plate, muscle-tendon insertion
type I diabetes training
- can train vigorously but avoid hypoglycemia
- to control blood glucose, avoid injecting insulin into the working muscle to prevent an increased rate of uptake at muscle
inhaler helps with
bronchospasms
asthmatics should avoid what sport
scuba diving
sarcopenia
age-related loss of muscle mass, decrease in muscle size and decrease in number of fibers
muscle mass decline per year after age 50
1-2% per year
resistance training is most effective to reduce this loss
VO2 max decline per year after age 40
1% per year
why does endurance and VO2 max decline with age?
- decrease in maximal CO and a-vO2 difference
- exercise economy and lactate threshold don’t change with age, only VO2 max
fatigue
inability to maintain power output or force during repeated muscle contractions
types of fatigue
- central fatigue (CNS)
- peripheral fatigue (neural factors, mechanical factors, energetics of contraction)
free radicals
- molecules with an unpaired electron in the outer orbital
- capable of damaging proteins and lipids in muscle due to the unpaired electron
free radicals and fatigue
- fr only contribute to fatigue in exercise over 30 mins long
- damage contractile proteins (limiting number of cross bridges) and depresses Na/K pump activity
antioxidants and fatigue
antioxidants do not prevent fatigue
moderate-duration performances
- 3-20 mins
- VO2 max depends on high maximal stroke volume and high arterial oxygen content
intermediate-duration events
-12-60 minutes
- important factors:
- VO2 max, running economy (exercise efficiency), environmental factors, hydration levels, lactate threshold
long-term performance needs
- carbohydrate utilization rates need to be maintained
- ingest carbs, fluids, and electrolytes during the event
ultra-endurance events fat oxidation and risks
- fat oxidation after an event is 3.5 times higher
- risk of hyponatremia (low sodium blood levels) (only affects 4% of athletes)
density of fat free and fat tissues
density of fat free tissues: 0.9
density of fat density: 1.1
how to convert body density to % fat
siri equation
%fat=(495/body density) -450
near infared interactance (NIR)
uses an infrared light beam
Ultrasound to measure body composition
measures thickness of subcutaneous fat
nuclear magnetic resonance (NMR)
- measures volumes of specific tissues
dual energy xray absorptiometry (DEXA)
“gold standard” test
measures how body weight breaks down into fat, bone, and lean tissue
density equation
density = mass/ volume
siri equation
%fat = (495/body density) -450
Archimedes principle
volume submerged object = volume of water displaced
underweight body fat %
< 18.5
normal body fat %
18.5-24.9
overweight body fat %
25-29.9
obese body fat %
30-34.9
extreme overweight body fat %
> 35
diseases related to obesity
hypertension
type 2 diabetes
coronary heart disease
stroke
risk waist circumference for men and women for cardiovascular disease
men: >102 cm
women: >88 cm
risk waist to hip ratio for cardiovascular disease in men and women
men: >0.95
women: >0.80
cause of obesity
no single cause
25% genetic
30% environmental factors
energy balance
adherence to diet is more important than type of diet
basal metabolic rate (BMR)
represents 60-70% of total energy expenditure
what can affect BMR
energy expenditure, gender, lean mass percentage, altered energy balance
static energy balance
a positive caloric intake of 250kcal*day = 24 lb weight gain over 1 year
contributions to decreased resting BMR during diet-induced weight-loss
- decrease in lean mass
-decline in thyroid hormone (T3) - decrease in sympathetic nervous system activity
thermic effect of food or thermic feeding effect (TEF)
energy used by the body to digest, absorb, and process food
% of TEF on energy expenditure
10-15%
brown adipose tissue
keeps body warm, increases heat production ( and energy expenditure/metabolic cycles in which ATP is lost ie Na/K pump)
exercise to maintain weight
150-250 min per week of moderate intensity exercise
exercise to achieve and sustain weight loss
> 250 min per week of moderate-intensity exercise
ergogenic aids
substances or phenomena that are work-producing and are believed to increase performance
dietary supplement that is proven to improve performance
creatine
what happens when you take creatine
increases intramuscular phosphocreatine (PC), ability to maintain force and power
how much creatine do you need to increase intramuscular creatine
20-25 g/day loading dose (5-7days), maintain 2-5g/day
potential side effects of creatine use
gastrointensinal distress, nausea, cramping
- no long-term adverse effects
creatine and myopathy conditions
may improve strength for muscular dystrophies, may have negative effects with metabolic pathways
breathing oxygen for athletic performance
no practical use
- only small increase in time to exhaustion but blood O2 returns to normal within a few breaths
blood doping
infusion of red blood cells to increase hemoglobin concentrations
blood doping and aerobic performance
can increase performance 3-34%, (Hb 8-9%, VO2 4-5%) effects last 10-12 weeks
blood buffer (sodium bicarbonate)
H+ buffering
side effects: diarrhea and vomiting
effects of amphetamines
-cause increased arousal and perception of increased energy and self-confidence
- extend time to exhaustion,
- mobilize FFA, spare muscle glycogen
- interfere with signals of fatigue
- improve performance in fatigued subjects only
B2-agonists: clenbuterol and salbutamol
- used to treat asthma
- athletes take to increase muscle mass (10-20%)
- type I to type II fiber conversion
- hypertrophy of type II fibers
caffeine
-central nervous system effect
- mobilization of glucose and fat
- heart and skeletal muscle
