THER EX: Exam I Flashcards
(39 cards)
Endurance
= Ability to perform work for long period
– Resistance to fatigue
Cardiovascular vs. muscular endurance ~
- Exercise intensity (or power generated)
- CV = low to moderate
- Muscular = high
- Exercise intensity (or power generated)
- Type of energy system used
Fitness
= Ability to perform physical work
Different ways to define:
1) Cardiorespiratory function
2) Muscle strength and endurance
3) Musculoskeletal flexibility
4) Body composition
NOTE: Aerobic or cardiovascular fitness level rated from results of by submaximal or maximal testing
Energy systems
= Metabolic systems involving a series of biochemical reactions that result in the formation of ATP
- ATP releases inorganic phosphate to become ADP
- Breaking bond releases ENERGY
- ADP + Pi = ATP
(1) Phosphagen or ATP-PC (anaerobic)
(2) Anaerobic glycolytic
(3) Aerobic oxidative
- - Aerobic glycolysis
- - Krebs cycle
- - Electron transport chain
Phosphagen (ATP-PC) system
= Phosphocreatine (P-C) breaks into P + C + energy
– Energy combines with ADP and P to form ATP
Characteristics:
- Immediately available (outside mitochondria)
- Maximal power (high intensity) (e.g., shot put)
- No oxygen required
- Small maximal capacity (limited by supply of PC in muscle)
Used for:
- Initiation of any type of activity (first 20 seconds) until other systems activated
- Intermediary throughout long term activity (short duration)
NOTE: “Capacity” refers to the concentration or substrates or enzymes needed for the production of energy by a given system (e.g., glucose, phosphocreatine, aerobic enzymes, ATPase)
Anaerobic glycolytic system
= Glucose converted to lactic acid and ATP (energy)
Characteristics:
- No oxygen required
- Quick availability (outside mitochondria and few steps)
- Intermediate maximal power (e.g., 400 m sprint)
- Limited capacity because of lactic acid buildup
- Lowers pH, which halts enzymatic activity needed for conversion of glucose
- Ability to remove lactic acid is limiting factor
- Poor efficiency (only 2 mol ATP per mol glucose)
- High amount of heat produced (~70%)
Used for:
- Relatively high intensity (e.g., sprint)
- 30-90 seconds of exercise (main source)
Aerobic oxidative system
= Aerobic glycolysis to Krebs cycle to electron transport system (ETS)
Characteristics:
- Oxygen required (to remove H+ ions)
- KC and ETS inside mitochondria
- High maximal capacity
- Small maximal power (low intensity)
- Very efficient (36 mol ATP / mol glucose)
- Less heat produced than anaerobic glycolysis (56%)
- Slow to initiate/maintain supply
- Can use fat (beta oxidation) & protein as energy source (lasts longer)
- Only at low intensities (even slower process)
Lactate thresholds (untrained vs. trained)
= Exercise intensity at which lactic acid starts to accumulate in the blood
– Lactate produced (via anaerobic glycolysis) faster than it can be removed
– Sudden increase in lactic acid related to intensity of exercise
Factors causing lactate accumulation:
– Low tissue O2
– Reliance on glycolysis
– Activation of fast-twitch fibers (high force production)
– Reduced lactate removal
Untrained:
- At ~50% VO2max ability to generate ATP aerobically is exceeded by demand
- Goes back to anaerobic process at higher levels of intensity
- Aerobic system not fast enough for high intensity (energy demand > rate of supply)
- Cannot maintain higher intensity as long as trained person because of lactic acid build up
- Decreasing intensity allows switch back to aerobic (lower demand)
Trained:
- At ~75% VO2max ability to generate ATP aerobically exceeded by demand
- Able to perform a higher level of intensity aerobically
Factors affecting energy production (rate and duration)
(1) Concentration of enzymes and substrates
- - “Capacity” of system) (e.g., glycogen, PC, fat mobilizing enzymes)
(2) Temperature
- - PE converted to KE + heat
- - Aerobic more efficient than anaerobic (56 vs. 73% heat produced)
- - Enzymes function only in narrow temperature range
- - Increased heat places demand on circulatory system (to dissipate)
- - At too high temperatures energy production stops
- - Switch to aerobic production reduces heat increase (more efficient)
- - Increases work capacity
(3) pH (normal 7.34-7.36)
- - Metabolic processes stop <6.9 or >7.8
Specificity principle
= Specific systems respond to specific training stimuli
– Demands or stresses on a specific system lead to adaptations
- Relates to training for function or sport
- Mode of exercise should be selected most appropriate for goals of patient
Measurement of energy expenditure
(1) Direct calorimetry = human calorimeter to measure heat production as function of energy expenditure
- - 1 kcal = energy to heat 1 kg of water 1 degree C
- - Expensive and involved (only 2 in country)
(2) Indirect calorimetry = correlate amount of oxygen consumed to energy expenditure or work rate
- - 1 L oxygen ~ 5 kcal
- - Open circuit spirometry = measures volume, O2, and CO2 of expired air during exercise test
- - Used to compute amount of O2 consumed
- - Provides accurate estimate of energy expended
Metabolic equivalent
= Resting oxygen consumption per kg per minute (3.5 ml/kg/min)
Activity intensity ~ METs:
- Light = < 3 METs
- Moderate = 4-6 METs
- Heavy = 6-8 METs
NOTE: Estimates of activity intensity for “average” individuals
- Should not be used for individualized exercise prescription
- Large differences among individuals in exercise capacity
- Untrained person may have a maximum capacity of 5 METs, thus 4-6 METs would not be considered “moderate”
- Elite athlete with maximum capacity of 15 METs would consider 4-6 METs as being light
Maximum oxygen consumption
= Maximum amount of oxygen consumed per minute during maximal aerobic effort
– Performing exercise that involves large muscle groups
= How much work can be done aerobically
– Measured with VO2-max testing or estimated with sub-max testing
Other terms:
- VO2-max or “peak” VO2
- Peak may be more accurate b/c cannot know if max was reached
- Maximal aerobic capacity
- Maximal oxygen uptake
Units: ml/min or ml/min/kg
Other criteria:
(1) Lactic acid accumulation in blood
- - Indicates switch from aerobic to anaerobic when capacity exceeded
(2) Respiratory exchange rate (RER) (CO2/O2 of air exhaled) > 1
- - CO2 removed from blood to neutralize/buffer acidity from lactic acid accumulation
(3) Reaching age-predicted max HR (variable and less accurate)
NOTE: As resistance or intensity increase, O2 use increases until aerobic capacity maximum is met, then switch to anaerobic energy system causes plateau and decrease in O2 uptake because lactic acid accumulation (pH drop) halts enzymatic action of aerobic system
Factors affecting VO2-max
Two main factors:
(1) O2 delivery to tissues
(2) O2 use by tissues
Depends on:
- Delivery
- Respiratory intake of O2
- O2 binding capacity of blood
- Perfusion at lung and body tissues
- Cardiac function (e.g., cardiac output)
- Tissue use
- Oxygen extraction capabilities
- Muscular oxidative potential (e.g., slow vs. fast twitch)
(1) Pulmonary
- Lung volume (FVC) = size of lungs
- Maximum voluntary ventilation (MVV) = max volume inhaled/exhaled at fastest RR
- Perfusion of lung tissues = gas exchange at alveoli ~ capillarization and CO of RV
(2) Circulatory
- Perfusion = gas exchange at tissues (e.g., muscles)
- CO of LV
- O2 binding capacity
(3) Metabolic
- O2 extraction
- Muscles oxidative potential
Fick equation
VO2 = CO x a-vO2 difference
= HR x SV x a-vO2 difference
Normal values:
Resting:
HR 45 (athlete) - 70 (untrained) bpm
SV 80-90 ml (elite athlete >100 ml)
a-vO2 difference 40-50 ml (20-25% extraction) (regardless of training)
– Saturated blood = 200 ml/l
VO2 3.5 ml/kg/min (1 MET) (regardless of training)
Maximum:
HR: 75-85%
SV: 90-100 ml (elite athlete >150 ml)
– Training may increase by 10-15%
a-vO2 difference 140-160 ml (70-80% extraction)
– Trained person has higher max extraction
VO2: 30 (untrained) - 50 (fit normal) - 80 (elite) ml/kg/min
Steady state (rate)
= Oxygen uptake meets oxygen demand
- Energy production primarily based on aerobic energy system
- Minimal lactic acid accumulation (aerobic)
- Requires sufficient duration for aerobic system to start producing ATP (>90 seconds)
- Must reach steady state before measuring energy cost of given activity
NOTE: Fit person more efficient at producing ATP via aerobic system, reaches steady state sooner, and thus has lower oxygen debt
Oxygen deficit
= Oxygen used during exercise to break down lactic acid and dissipate heat
- Oxygen NOT used for energy production
- Due to anaerobic energy production
- Generated in early stages of exercise before aerobic system produces ATP
- Before reaching steady state
- Greater for less fit person performing same work
- Takes longer to reach steady state
- Greater for higher intensity exercise
- Greater anaerobic contribution
- Longer recovery time required for high oxygen debt
- To restore system to equilibrium O2 levels
Fick equation components response to exercise
HR: Linear increase with workload
VO2: Linear increase with workload until plateau/decrease at max
– Plateau at max because O2 demand > O2 use = switch to anaerobic energy production
– Switch to anaerobic causes lactic acid accumulation
– Acidic environment halts enzymatic activity needed for aerobic production
SV: Gradual increase to 150% resting at 50-60% workload then plateau/decrease at max
– Decrease near max due to:
– Large increase in HR reduces time heart is in diastole, reducing filling time and EDV/SV
– Long duration exercise causes decreased blood volume due to sweating (decreases EDV)
– Exercising in excess heat can cause reduced SV
a-vO2 difference: Increases from 20-25% at rest to 70-75% at max
Criteria for determining peak VO2
(1) Lactic acid accumulation in blood
- - Switch to anaerobic energy system when O2 demand > O2 supply
(2) Respiratory exchange rate (RER)
- - Normally CO2 = O2 expired
- - As pH drops due to lactic acid, CO2 concentration of blood is reduced to neutralize acidity
- - More CO2 expired
- - RER = CO2/O2 expired > 1
(3) Reach age-predicted maximum HR (220 - age)
BMI calculation and classes
= (weight in kg)/(height in m x height in m)
< 18.5 = underweight
18.5-25 = normal
25-30 = overweight
> 30 = obese
Purposes of fitness testing
(1) Educate patients about fitness status relative to age- and gender-specific norms
(2) Provide data for the development of exercise program prescriptions
(3) Collect baseline and follow up data to evaluate progress of exercise program participants
(4) Motivate participants by establishing fitness goals
(5) Stratify cardiovascular risk
Pre-fitness testing components
(1) PT exam and evaluation
(2) Health screening (risk factors or symptoms)
- - Questionnaire to assess readiness for activity (e.g., PAR or AHA/ACSM Q)
- - Signs or symptoms of cardiopulmonary disease
- - CAD risk factors
- - Comprehensive health and activity questionnaire
(3) Risk stratification (low, moderate, or high)
(4) Medical exam and supervision requirements (based on risk classification)
Fitness testing risk stratification
Low:
- No signs and symptoms or diagnosis of disease (asymptomatic)
- < 2 CVD risk factors
- Can safely pursue physical activity or exercise program w/o medical exam and clearance
- No med exam or supervision needed for low/vigorous intensity ex or submax/max testing
Moderate:
- No signs and symptoms or diagnosis of disease (asymptomatic)
- > or = 2 CVD risk factors
- Can safely engage in LOW/MOD intensity physical activities w/o med exam and clearance
- No med exam or supervision needed for low intensity ex or submax testing
- Recommended medical exam and exercise test before doing vigorous intensity exercise
- Med exam and supervision recommended for vigorous intensity ex or max testing
High:
- Diagnosed disease OR
- > or = 1 signs and symptoms of CV, P, or M disease
- Requires medical exam and clearance before starting physical activity of ANY intensity
- Med exam and supervision recommended for LOW/VIG intensity ex or submax/max testing
Fitness test components
Test order:
(1) Resting measurements (e.g., BP, HR)
(2) Blood draws
(3) Body composition
(4) Cardiorespiratory endurance
(5) Muscular fitness
(6) Flexibility
Assumptions of submaximal testing
(1) Age-predicted maximal heart rate (AAMHR) = actual maximum heart rate (e.g., 220 - age)
(2) Linear relation between HR/VO2 and work load
(3) Steady state HR achieved at each work load
- - Steady state = oxygen uptake meets oxygen demands
- - Ensures work is done aerobically (minimal anaerobic input)
- - Requires duration sufficient for aerobic system produce ATP (e.g., 2-3 min per stage)
(4) Mechanical efficiency is the same among individuals (i.e., cyclist vs. runner)
(5) Individual is not on medications that alter HR response (e.g., beta blockers)
