EXERCISE TOLERANCE Flashcards
EXERCISE TESTING: description & indications
D: - Exercise testing before initiating physical activity program not routinely recommended except for individuals at risk
- Nevertheless, info gathered from exercise test useful to design effective Ex Rx for lower risk individuals
I: - Evaluating patient with chest pain or dyspnea with other findings suggestive, but not diagnostic or coronary artery disease (CAD)
- Risk stratification post-myocardial infarction
- Determining prognosis & severity of coronary artery disease
- Evaluating effects of medical & surgical therapy
- Screening for latent coronary disease
- Evaluation of congestive heart failure
- Evaluation of arrhythmias
- Evaluation of functional capacity & formulation of exercise prescription
- Evaluation of congenital heart disease
- Stimulus to change in lifestyle
CARDIORESPIRATORY FITNESS: CPET
Non-invasive test assessing performance of heart & lungs during exertion
- Least 10 to 15 minutes
- Safety: Death rate <0,01% & life-threatening heart rhythm incidence < 0,2%
- Increasing loading in 20W every minute, 50-60 RPM: Cycle- ergometer
- Increasing ramp or speed: Treadmill
=> up to reach 85-100% of theory maximum heart rate
=> Maximal tests accurate but require medical monitoring when. Sub maximal tests less accurate, but safer & faster than maximal test
Maximal
1. VO2 plateau despite increase in workload <2mL ḱ g-1 ḿ in-1or<150ml ḿ in-1
2. HR within 10 beats of age-predicted max
3. > 8 millimoles per liter (blood lactate concentration) Large anaerobic component at end of test
4. Respiratory Exchange Ratio (VCO2/VO2) of 1.15 or above Large respiratory compensation (high VCO2) for buffering of high H+ blood concentration
5. A rating of perceived exertion (RPE) 17 on the 6–20 scale or 9 on the 0–10 scale
Submaximal
Tests generally terminated at predetermined level 70% of HRR
85% of age predicted HRmax
HRR = % of target intensity (HRmax - HRrest) + HRrest
CARDIORESPIRATORY FITNESS: protocols: description & ≠ types
- Ramp test: Avoidance of large & unequal increments in workload
- Uniform increase in hemodynamic & physiologic responses
- More accurate estimates of exercise capacity & ventilatory threshold
Ex: 3m rest, 3m free-load warm-up & gradual increase in load until exercise stopped Followed by 6-m active recovery & 1-minute passive recovery
Power increments calculated. Maintain 50-60 RPM during test
Efficient protocol consists of 3 minutes of rest, followed by 3 minutes of unloaded pedaling followed by incremental phase of exercise every minute (5 to 25 W/minute) - VO2unloaded (mL/min) = 150 + (6× weight, kg)
- VO2peak (mL/min) = (height: cm - age: years) × 20 Ramp (w/min) = VO2peak− VO2unloaded/100
- VO2unloaded (mL/min) = 150 + (6× 80kg) = 630
- VO2peak (mL/min) = (170cm – 30yo) × 20 = 2800
- Ramp (w/min) = 2800 − 630 /100 = 22 W/min
- In general, protocols with larger incremental workload adjustments such as Bruce better suited for screening younger and/or physically active individuals
- Smaller increments such as Naughton or Balke preferable for older or deconditioned individuals & patients with chronic diseases
Tableau
CARDIORESPIRATORY FITNESS: conversion & spirometry
C: - VO2 (L/min): 3
- Body Weight: 75 kg
- 3 L/min x 1000 ml/L = 3000 ml/min - 3000 ml/75 kg = 40 ml/kg/min
VO2 typically expressed clinically in relative (mL/kg /min) as opposed to absolute (L/min) terms, allowing for meaningful comparisons between individuals with differing body weight
S: Spirometry used to measure breath-by-breath measures of oxygen uptake (VO2), carbon dioxide output (VCO2) & ventilation (VE)
- Represents internal metabolic work & directly proportional to external work rate applied through cycle ergometer or treadmill
Exercise limitation
Data integrated with standard variables measured during exercise testing, including heart rate, blood pressure, work rate, electrocardiography findings & symptoms, to provide comprehensive assessment of exercise tolerance
CARDIORESPIRATORY FITNESS: General indications for stopping exercise test
- Onset of angina
- Drop in SBP of > 10 mmHg with increase in work rate or if SBP decreases below value obtained in same position prior to testing - Excessive rise in BP: systolic pressure > 250 mmHg and/or diastolic pressure > 115 mmHg
- Shortness of breath, wheezing, leg cramps or claudication
- Signs of poor perfusion, light-headedness, confusion, ataxia, pallor, cyanosis, nausea or cold & clammy skin
- Failure of HR to increase with increased exercise intensity
- Noticeable change in heart rhythm by palpation or auscultation - Subject requests to stop
- Physical or verbal manifestations of severe fatigue
- Failure of testing equipment
CARDIORESPIRATORY FITNESS: Modes of testing
Tableau
CARDIORESPIRATORY FITNESS: description
- Cardiorespiratory Fitness related to ability to perform large muscle, dynamic, moderate to vigorous intensity exercise for prolonged periods of time
VO2max = Q x (CaO2 – CvO2) - Max volume of O2 consumed by body each minute during large muscle group exercise at high intensity
- Average for 20yo female: 32-38 mL/kg/min - Average for 20yo male: 36-44 mL/kg/min
VO2max = 15 x (HRmax/HRrest)
Cardiorespiratory fitness (VO2)
(a) Low levels of CRF associated with markedly increased risk of premature death from all causes & specifically from CVD
(b) Increases in CRF associated with reduction in death from all causes
(c) High levels of CRF associated with higher levels of habitual physical activity
VO2max = Q x (CaO2 – CvO2)
Increased SVmax - Increase Preload (End Diastolic Volume) during filling
‣ Increase Venous return
‣ Increase Ventricular volume - Decrease Afterload (End Systolic Volume) during emptying
‣ Decrease Arterial constriction
‣ Increase Maximal muscle blood flow - Increase Contractility of heart
‣ increased force of contraction - Even in absence or minimization of change in Q, important increase in V̇ O2max during exercise result from increased oxygen extraction
- At rest only about 25% of O2 carried in blood taken up by muscle
- During heavy exercise 85% of O2 taken up by muscle
Factors affecting O2 extraction & utilization: Hemoglobin, capillaries, mitochondria & fibers
CPET: Cardiovascular response, metabolic response & ventilatory response
CV: - As exercise intensity increases, sympathetic discharge becomes maximal, resulting in vasoconstriction in most circulatory body systems, except in exercising muscle & in cerebral & coronary circulations
- CO increases & peripheral vascular resistance decreases in response to vasodilation of resistance vessels within exercising skeletal muscle
- Diastolic blood pressure remain unchanged or decrease to small degree, each of which considered normal response
M: - Ventilatory expired gas responses often used in clinical settings as estimation of point at which lactate accumulation in blood occurs, sometimes referred to as lactate or anaerobic threshold
- Assessment of physiologic phenomenon through ventilatory expired gas typically referred to as ventilatory threshold (VT)
V: image
CYCLE ERGOMETER TEST: def, goals, outcomes measured, description + VO2 prediction
- Assessment tool to identify exercise tolerance Goal: Identify Max Work Rate
- Less specific that CPET
Outcomes measured:
• Heart Frequency
• Respiratory Frequency
• Systemic Blood Pressure
• Peripheric Oxygen Saturation
• Perceived Dyspnea and Lower limb fatigue - Protocols based on maintenance (time) or incremental of exercise work rate until exhaustion: - Maintain 50W (50-60 RPM) until exhaustion
- Increase 20W every 2 minutes until exhaustion
Images
6MW: description, contraindications, equipment & equation reference
D: - Developed by American Thoracic Society & officially introduced in 2002
- 6MWT used in preschool children (2-5 years), children (6-12 years) adults (18-64 years), elderly adults (65+) with wide range of diagnoses including - Test initially designed to help in assessment of patient with cardiopulmonary issues
- Cooper test which designed by Kenneth H. Cooper in 1968 for US military use physical fitness test Aim: To run as far as possible within 12 minutes
- McGavin (1976) modified Cooper’s test to 12MWT & applied it on subjects with COPD along hospital’s indoor corridor
- Butland (1982) modified to 6MWT more reliable & less stressful. Standardized even on instructions
C: Absolute Contraindications
- Unstable Angina
- Recent myocardial infarction
Relative Contraindications
- HR>120bpm at rest - PAS>180 mmHg
- PAD>100 mmHg
E: 1. Countdown timer (or stopwatch)
2. Mechanical lap counter
3. 2 small cones to mark turnaround points 4. Chair easily moved along walking course 5. Worksheets on clipboard
6. Source of oxygen
7. Sphygmomanometer
8. Telephone
9. Automated electronic defibrillator
Équation voir cours
6MW: instructions & ventilatory response
I: BEFORE
- 6 minutes = long time to walk, so you will
be exerting yourself
- You are permitted to slow down, to stop & to rest as necessary, but please resume walking as soon as you are able - Remember objective = walk AS FAR AS POSSIBLE for 6 minutes, but don’t run or jog
DURING
Monitor signs & symptoms.
- Use following standard encouragements during test:
• 1 min “You are doing well. You have 5 minutes to go.”
• 2 min “Keep up good work. You have 4 minutes to go.”
• 3 min “You are doing well. You are halfway.”
• 4 min “Keep up the good work. You have only 2 minutes left.”
• 5 min “You are doing well. You have only 1 minute to go.” • 6 min “Please stop where you are.”
- Continuous monitoring of SpO2 & HR performed during test & results recorded each minute
- If patient stops during test, once SpO2 is >85% “Please resume walking whenever you feel able.”
VR: Maximal Voluntary Ventilation directly measured by 12–15 s deep & rapid breathing maneuver or estimated from equation: Forced Expiratory Volume in 1s [(FEV1 L) X 40]
VEmax / MVV
< 70% of MVV = No ventilatory limitation > 70% of MVV = Ventilatory limitation
Relationship between VEmax & MVV, typically referred to as ventilatory reserve, traditionally defined as percentage of MVV achieved at maximal exercise
FEV1 = 2.1L
Pred MVV (2.1 X 40) = 84
VEmax = 78
VEmax/MVV = 92% (Ventilatory limitation)
