Exercise Testing Exam 2
Primary limiting factors associated with short term events (10-180 seconds)
Predominantly (.70%) anaerobic, using the high force, fast-twitch fibers · Primary energy source is anaerobic glycolysis, which causes an accumulation of H= in muscle as well as blood
Linear responses
gains are made continuously over time
What are the field/functional tests fro cardiorespiratory fitness
- 6 minute walk test -1.5 mile run. walk test - 1 mile walk test
HR
+/- 10 bpm of predicted max HR (220-age)
What are the 6 key measurements that should measured during EXERCISE TESTING
- HR - BP - Arterial Blood O2 saturation - EKG - RER
How do you determine the predicted max workrate? Predicted VO2max?
- HR/VO2 relationship is extrapolated and used to predict the peak work rate and VO2 max
How do you know when you should add an extra minute to a stage?
- If the difference in HR is < 5 bpm, a steady state is assumed; if not, an additional minute is added to the stage
How do you determine what workload to use in the 2nd Stage?
- Look at first stage then look at HR; HR<86, 2nd=600 kgm: HR(86-100), 2nd= 450 kgm: HR>100, 2nd = 300 kgm
Who should a resting, supine standard 12-lead ECG performed on prior to exercise?
-A brief history and physical examination are required - Subjects with a history of worsening unstable angina or decompensated heart failure should not undergo exercise testing until their condition stablilizes -Abnormal hemodynamic responses to exercise in these patients could require early termination of testing - Why is this recommended? · A resting supine standard 12-lead ECG should be obtained before exercise to compare previously obtained standard ECG's to determine if changes have occurred over time
Recruitment patterns associated with TYPE 2X
-At about 75% VO2 Max, type 2X fast-twitch are recruited · Low mitochondrial content · Adds to the tension generated by Type 1 and IIa.
What happens to the air pressure at altitude?
-Atmospheric pressure decreases with increasing altitude, the air is less dense, and each liter of air contains fewer molecules of gas -The decrease in partial pressure of O2 (PO2) with increasing altitude has a direct effect on the saturation of hemoglobin and, consequently oxygen transport · i. Hypoxia is the reduce PO2 · ii. Normoxia: describes PO2 at sea level · III. Hyperoxia is an elevated PO2 relative to sea-level
Recruitment patterns associated with TYPE 2A
-Between 40-75% VO2 Max type 2a fast-twitch, fatigue resistant fibers are recruited, in addition to type 1 fibers · Rich in mitochondria and rely heavily on oxygen delivery, but also have a great capacity to produce ATP via anaerobic glycolysis · If oxygen delivery to this fiber is decreased, or its ability to use oxygen is decreased, tension development will fall
Testing procedure
-Detailed explanation of the testing procedure · Nature of the progressive exercise, symptom and sign end points, and possible complications
Primary limiting factors associated with Ultra short term events (< 10 seconds)
-Limited by the fiber type distribution and the number of muscle fibers recruited, which is influenced by the level of motivation and arousal · Primary energy sources are anaerobic, with the focus on phosphocreatine
Naughton Protocol
-Provide more modest increases in workload between stages and are useful choices for elderly, deconditioned patients
Bruce Protocol
-Some subjects, especially those who are elderly, obese or have gait difficulties, are forced to stop exercising prematurely because of musculoskeletal discomfort or an inability to tolerate the high workload increments
Relationship to NMJ
-The action potential appears to reach the neuromuscular junction even when fatigue occurs -Measurements of electrical activity at the NMJ and in the individual muscle fibers suggests that this is not a primary site of fatigue
Recruitment patterns associated with TYPE 1
-Up to about 40% VO2 max, the type 1 slow-twitch oxidative muscle fiber is recruited · Dependent upon a continuous supply of blood to provide oxygen needed for ATP generation · Any factor limiting supply to this fiber (altitude, dehydration, blood loss, or anemia) would cause a reduction in tension development
How do you know when to stop the test?
-When 2 HR values greater than 110 bpm are obtained
What 4 factors lead to the decreased lactate accumulation following endurance training?
1. Increased capacity to use fats instead of carbohydrates 2. Increased mitochondrial volume 3. Increased H type of lactate dehydrogenase 4. Increased concentration of MCTI
body mass (kg)
1 kg = 2.2 lbs
What is the primary adaptation that accounts for the improvement in stroke volume with endurance training?
1. An increase in end-diastolic volume results in stretch of the left ventricle and a corresponding increase in stroke volume via the frank starling mechanism 2. The primary mechanism is an increase in plasma volume that occurs following endurance training, which subsequently increases ventricular preload
Does it take as long to increase VO2max to previous training levels after a period of detraining?
1. Only 1 week of detraining results in a loss of about 50% of what was gained during 5 weeks of training 2. 3-4 weeks of retraining were required to achieve the former trained levels. 3. Why or why not? - Muscle mitochondria increases at the onset of exercise, doubling in about 5 weeks of training -Muscle fiber mitochondrial content rapidly decreases with detraining
What are the two main assumptions that allow us to estimate VO2max from a submax VO2 test?
1. That a steady-state heart rate and VO2 can be achieved and is consistent for each work rate and each day · That a linear relationship exists between HR and work rate · That maximal workload is indicative of VO2 max · Thar maximal HR at any given age is uniform 2. The mechanical efficiency during cycling or treadmill exercise is constant for all individuals · Efficiency is defined as the energy or VO2 required for any given workload · In a normal healthy adult efficiency is about 10 ml x min-1 increase in VO2 for every 1 watt increase in work rate.
What two adaptations account for the improvement in a-vO2 difference?
1. The training induces increase in the a-VO2 difference is due to an increased O2 extraction from capillary blood to muscle mitochondria -Increased capillary density - Increased mitochondrial volume 2. Changes in capillary density parallel changes in leg blood flow and VO2max with training 3. Increase in mitochondrial volume increases the muscle fibers ability to consume oxygen
What cardiorespiratory components result in the improvement in VO2max? HINT: Fick Equation
1. Training induced increases in VO2 max are due to adaptations in both cardiac output and the a-VO2 differences 2. Endurance training studies in young sedentary subjects suggest that about 50% of the gain in VO2 max is due to stroke volume increases and 50% due to increased oxygen extraction. - An increase in maximal SV is the sole contributor to increases in maximal cardiac output.
What are the typical features of exercise that improve VO2 max?
1. Types of exercises -Dynamic exercises using a large muscle mass (running, cycling, or swimming) 2. Minutes per session -20-60 minutes per session 3. Times per week - 3-5 times per week 4. Intensity related to VO2 max - 50-85% VO2 max
G is percent grade as decimal
10% = 0.1
Speed in m min-1
1mph = 26.8 m min-1
VO2 plateau
< or = to 150 mL/min increase intensity
RER
> 1.15 -Ratio of CO2 expired to O2 consumed
RPE
> 17 (6-20 borg RPE scale)
At what WBGT would an athletic event be cancelled
> 29
Possible sites/causes of central fatigue
?
How long before testing should someone stop eating?
No food for 3 hours before the test
How much of VO2max in untrained individuals does genetics account for?
Approximately 50% of an untrained individuals VO2 max is determined by their genetic makeup -Differences in mitochondrial DNA may be the primary component determining individual differences in initial (untrained) VO2 max and the training induced improvements in VO2 max
What change accounts for the reduction in VO2max beyond about the 21st day of detraining?
Between the 21st and 84th days of detraining, the decrease in VO2 max is due primarily to the decrease in the a-VO2 difference
Heat exhaustion
Collapse with or without loss of consciousness, suffered in conditions of heat and high humidity, largely resulting from loss of fluid and salt by sweating
Metabolic rate
Core temperature is proportional to metabolic rate, therefore decreasing the work rate decreases the heat load, as well as the strain on the physiological systems that must deal with it.
Electrical Stimulation
Decline in force production
Hypertrophy
Defines an increase in muscle fiber cross-sectional area -Current evidence indicates that 90-95% of the increase in muscle size following resistance training occurs due to hypertrophy Weight training elicits a greater degree of hypertrophy in type II fibers
Hyperplasia
Defines an increase in the number of muscle fibers within a specific muscle
Primary limiting factors associated with moderate length performance (3-20 minutes)
Dependent on oxidative energy production · The factors limiting performance include both the cardiovascular system and mitochondrial content of the muscles · Races lasting fewer than 20 minutes run at 90-100% of maximal aerobic power, so athletes with the highest VO2 max have an advantage
The initial decrease in cardiorespiratory fitness or VO2 max (first 12 days) is the result of what changes (refer to graph)?
Due primarily to decreases in stroke volume subsequent to decreases in plasma volume
Hyperthermia
Elevated body temperature due to failed thermoregulation that occurs when a body produces or absorbs more heat than it dissipates
What is the effect of someone's VO2max on their ability to improve their VO2 with training?
Endurance training programs of 2 to 3 months will increase VO2 max between 15-20% - Those who start training with a high VO2 max may only experience an improvement of 2-3% -Individuals with low initial VO2 max may increase VO2 max by 50%
Environmental temp
Environmental temps greater than skin temperatures results in heat gain. · Evaporation of seat must compensate if body temperatures is to remain at a safe value.
Acclimation to heat
Exercise in the heat for 10-14 days at various exercise intensities and durations results in acclimation, which: · Increase plasma volume and capacity to sweat · Lowers body temperature and heart rate response · Reduces salt-loss in sweat
Muscle Weakness
Failure to generate maximum force
Voluntary exercise
Failure to maintain the expected or required output
Heat syncope
Fainting or excessive loss of strength because of excessive heat
Heat Stroke
Final stage of heat exhaustion in which thermoregulatory system shuts down to conserve depleted fluid levels
Hydration & heat
Inadequate hydration reduces sweat rate and increases the chance of heat injury · Generally there are only minor differences between water, electrolyte drinks, or carbohydrate-electrolyte drinks in replacing body water during exercise
Black bulb temperature
Is a measure of the radiant heat load measured in direct sunlight
Wet bulb temperature
Is a measurement of air temperature with a thermometer whose mercury bulb is covered with a wet cotton wick (which provides an index of relative humidity)
Long term strength development comes as the result of an increase in what?
Muscle size
Primary limiting factors associated with long term performance (1-4 hours)
Performances greater than 1 hour, the ability of the muscle and liver carbohydrate stores to supply glucose may be exceeded. Thus, requires a glucose supplement during long term performances.
Sarcolemma/Transverse Tubules (mechanisms peripheral fatigue)
Possible site due to inability to maintain Na/K concentrations during repeated stimulations
Purpose
Purpose of the test should be clear to subject/patient
5 criteria for reaching VO2 max/VO2 peak
RER HR VO2 Plateau RPE Subject
What is progressive overload principle
Refers to the concept that a system or tissue must be exercised beyond which it is accustomed in order for a training effect to occur.
Fitness level & tolerance to heat
Related to a lower risk of heat injury · Fit subjects can tolerate more work in the heat, acclimate faster, and sweat more
Primary limiting factors associated with intermediate length performances (21-60 minutes)
Requires the athlete to work at <90% VO2 max, therefore a person who can run at a high percentage of VO2 max will have an advantage · Dependent upon factors like the lactate threshold and efficiency · Given the length of the activity, environmental factors such as heat, humidity, and the state of hydration of the subject will play a role in the outcome
Should routine medications be taken? How?
Routine medications may be taken with small amounts of water
Possible mechanisms for peripheral fatigue
Sarcolemma/Transverse Tubules · Possible site due to inability to maintain Na+ and K+ concentrations during repeated stimulations · When Na/K= pump can't keep up, K= accumulates resulting in reduced action potential amplitude · If the Ap is reduced, the T-tubules will be altered resulting in an altered Ca++ release from the SR
Heat cramps
Spasmodic muscular contractions caused by exertion in extreme heat
Subject
Subject wants to stop
Dry Bulb temperature
The ordinary measure of air temperature taken in the shade
Reversability
The principle that the physiologic adaptations gained by exercising at an overload are quickly lost when training is stopped or reduced below the overload What are the typical features of exercise that leads to VO2 max improvements
Disadvantages of using a treadmill vs cycle ergometer
Treadmill: · Can't get accurate estimate of work rate (Just speed/incline) · Only incremental exercise (no ramp protocols) · Hands on rails or clinician result in inaccurate VO2 Cycle ergometer: · Unfamiliar task for many o Leads to leg fatigue prior to VO2 max if protocol is too aggressive
Which of these three plays the most important role in determining the severity of heat exposure on a given day?
Wet bulb is most important in determining severity of heat exposure
Humidity
Will also determine the rate of sweat evaporation A lower relative humidity will facilitate evaporation
Wind
Wind places more air molecules into contact with the skin and can influence heat loss in two ways: · Increase the rate of heat loss by convection · Increase the rate of evaporation.
How should someone dress
comfortable clothing and shoes
Cross-bridge cycling
look at review
Sarcoplasmic reticulum
look at review
Central Fatigue
o 1. Central fatigue: Occurs when factors located prior to the neuromuscular junction impair force generating capacity of the muscle a) Supraspinal failure b) Segmental afferent inhibition c) Depression of motor neuron excitability d) Loss of excitation at branch points e) Presynaptic failure
Identify at least 5 uses related to exercise testing
o 1. Evaluation of physical capacity and effort tolerance o 2. Detection of coronary artery disease (CAD) in patients with chest pain (chest discomfort) syndromes or potential symptom equivalents o 3. Evaluation of the anatomic and functional severity of CAD o 4. Prediction of cardiovascular events and all-cause death o 5. Evaluation of exercise-related symptoms o 6. Assessment of chronotropic competence, arrhythmias, and response to implanted device therapy o 7. Assessment of the response to medical interventions
What are the 3 potential general mechanisms of fatigue?
o 1. Lack of available energy to maintain ATP concentrations at myosin ATPase o 2. Inhibition of ATPase reactions by products formed in the energy-supply reactions o 3. Alterations in excitation-contraction coupling from the sarcolemma action potential to Ca++ release by the sarcoplasmic reticulum
What are the recruitment patterns associated with TYPE 1, TYPE 2A, TYPE 2X related to percentages of VO2max?
o 40% - Type I o 40%-75% - Type IIa o At about 75% - Type IIx
How can we characterize dose (absolute vs relative)?
o Absolute intensity refers to the energy or work required to perform the activity and does not take into account the physiological capacity of the individual -Power - VO2 - HR - METs o Relative intensity does not take physiological capacity into account -% VO2 max - %HR max - RPE - % lactate threshold
Know how to train (components of a session, improve aerobic performance, anaerobic power, strength.
o Aerobic performance Interval training - performance of repeated exercise bouts followed by resting period. Useful for increasing VO2 max Long, slow distance - requires greater involvement of aerobic energy production (better for endurance) High-intensity, continuous - high intensity training is also good for increasing VO2 max
Dose-response relationship, graph and definitions.
o Dose-response relationship - the change in effect on an organism caused by differing levels of exposure to a stressor after a certain exposure time
Exercise Prescription for cardiorespiratory fitness
o Exercise program must include dynamic, large muscle activities such as walking, jogging, running, swimming, cycling, and rowing o Minimum 2 sessions/week and gains in CRF level off after 3-4 sessions/week
US guidelines for physical activity
o Minimum of 150 min of moderate-intensity physical activity or 75 min of vigorous intensity physical activity o Range is 150-300 min for moderate and 75-150 min for vigorous o at least 1 set, or 8-12 reps, of 8-10 exercise on two or more days per week to improve or maintain muscular strength and endurance
Peripheral Fatigue
o Peripheral fatigue: Occurs when factors located after the neuromuscular junctions impair force generating capacity of muscle
1 mile walk test
o The 1 mile walk test assesses cardiorespiratory fitness for men and women ages 20-69 o Walk 1 mile as quickly as possible and take their HR immediately at the end of the test
1.5 mile run/walk test
o The 1.5 mile run/walk test is conducted on a tract or flat measured surface -Subject attempts to cover the specified distance in the fastest possible time. -Walking is allowed but jogging/running should be main mode -Objective is to cover the specified distance in the shortest possible time while maintaining a steady exercise pace -Exercise HR at the end of the test, gender, body mass, and elapsed time, are used to estimate VO@ max of young (18-29 yr) adults.
6 minute walk test
o The 6-minute walk test is a functional test that can be used to evaluate submaximal exercise capacity. -Used in patients with chronic disease · Heart failure, chronic obstructive pulmonary disease, and peripheral arterial occlusive disease -Walk down a 100-foot corridor at patients' pace -Walk as much distance as possible in 6 minutes -Total distance walked is determined -Symptoms experienced by the patient recorded -Can be submaximal or maximal depending on patient disease status
2 advantages of using a treadmill for exercise testing vs a cycle ergometer
o Treadmill: -Can walk, jog, run -Gives a peak VO2 5-10% higher than cycling - Closely replicates daily ambulation (movement) o Cycle ergometer: -Very precise estimation of work rate (watts) · Can get work rate efficiency - Can be performed sitting or supine · < risk of falling -Can do step, incremental, or ramp protocols - Less movement artifact
What is ventilatory expired gas analysis used for?
o Ventilatory exrired gas analysis: Allows for the capture of Ventilation, VO2, and VCO2 through a face mask or mouth piece - What are its advantages?: · Provides most accurate non-invasive quantification of VO2 -What are its disadvantages? · Requires expensive equipment and specialized testing personnel
What are the 3 parts of a progressive exercise test?
o Warm up o progressive graded exercise with increasing loads and adequate time interval in each level o and a post-maximum effort recovery period at a low workload.
Rapid responses
o the benefits occur early and plateau
Delayed
occur only after weeks of training
Acute responses
occur with one or several exercise bouts but do not improve further
Know what things could be considered "test confounders"
§ Eating prior to test § Dehydration § Elevated body temperature § Temperature and humidity of the testing area § Emotional state § Medications Previous physical activity
What 3 "enhancements" lead to this increase in force output/efficiency?
§ Muscular Strength § Muscular endurance § Increases in muscle mass
Possible sites/causes of CENTRAL fatigue
§ Supraspinal failure § Segmental afferent inhibition § Depression of motor neuron excitability § Loss of excitation at branch points § Presynaptic failure
Cross-bridge Cycling (mechanisms peripheral fatigue)
· Functional arrangement of actin and myosin, Ca+2 being available to bind to troponin, ATP is needed for both activation of cross-bridge and dissociation · High H+ concentrations reduce force per cross-bridge, reduce force generated at a given Ca+2, and inhibit SR Ca+2 · High Pi has been shown to act directly on the cross-bridges to reduce binding to actin
How does this change in air pressure affect our ability to load oxygen into the blood as it passes through the lungs?
· If air is less dense at altitude, then there are fewer O2 molecules per liter of air. Therefore, to consume the same number of liters of O2, pulmonary ventilation must increase o Pulmonary ventilation is elevated at all altitudes · The extreme pulmonary response requires the ventilatory muscles, primarily the diaphragm, to work hard o May result in respiratory muscle fatigue, which can negatively impact exercise performance
Sarcoplasmic reticulum (peripheral fatigue)
· The SR Ca+2 pump rate may be slowed in fatigued muscles, which results in reduced SR Ca+2 stores. The net effect is that Ca+2 would be displaced from the release pool.
ATP Imbalances
· Typically, ATP concentration, even in extreme fatigue, only falls to 70% of its pre-exercise level · The factors that cause fatigue reduce the rate of ATP utilization faster than ATP generation