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The Art and Science of Exercise Prescription

John P. Porcari, Ph.D., FACSM, MAACVPR Program Director

Clinical Exercise Physiology University of Wisconsin-La Crosse

What are your goals when prescribing exercise?

Prescribe a program that: •  Promotes positive physiological changes •  Is safe and avoids injuries •  Fosters exercise adherence

Exercise is Medicine: Prescribing the Right Dosage

Medicine

•  What kind? •  How much? •  How often? •  How long?

Exercise

•  Type or modality •  Intensity •  Frequency •  Time or duration

FITT Principle •  Frequency •  Intensity •  Time or duration •  Type or modality

Frequency

• 3 - 5 days per week –  3 supervised sessions –  2 or more sessions on their own

Time / Duration

•  20 - 60 minutes of continuous activity

–  shoot for 30 - 40 minutes 1. reduces boredom 2. less chance for injury

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Latest Guidelines: AHA/ACSM 2007 “To promote and maintain health, older adults need moderate-intensity aerobic physical activity for a minimum of 30 minutes on 5 days each week or vigorous-intensity aerobic activity for a minimum of 20 minutes or more on 3 days each week.”

“walk often and walk far” Ades et al., Circulation: 2009

•  High Caloric Exercise for Cardiac Patients –  5-7 days week –  45-60 minutes/session –  50-60% peak VO2

–  goal of 3,000-3,5000 kcal/week

•  Standard Cardiac Rehabilitation –  3 days week –  25-40 minutes/session –  65-75% peak VO2

–  goal of 1200-1500 kcal/week

High Caloric Standard CR Kcal/day 615 269 Kcal/wk 3037 807 Weight Loss (kg) 8.2 3.7 Waist (cm) 7 5 Met Syndrome (%ò) 47 17

Results – 5 months Can you break up your workout

into smaller segments?

(e.g., 3 - 10 minute segments vs. 1 - 30 minute bout)

Type or Modality

•  Any large muscle, sustainable activity is acceptable

•  No one modality has proven to be superior, however those modes with an upper body component may have some advantages: –  increased upper body muscular endurance –  sharing of workload, so lower perceived effort

(RPE)

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Control Bike Tmill Stepper Skier

PrePost

Changes in aerobic capacity following 12 weeks of stationary cycling, treadmill walking, stepping, or simulated cross-country skiing

VO2 max (ml/kg/min)

Control Bike Tmill Stepper Skier

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1Weight loss (lbs)Body fat (%)

Changes in body weight and % fat following 12 weeks of stationary cycling, treadmill walking, stepping, or simulated cross-country skiing.

Change

Control Bike Tmill Stepper Skier

SPECIFICITY SAID PRINCIPLE

Specific

Adaptation

to

Imposed

Demands

Intensity

• 40 - 85% of maximal capacity

How do we get people there? •  Objective criteria

•  %VO2max or %VO2R •  %HRmax or HRR (Karvonen)

•  Subjective methods •  RPE •  Talk test

Relative Exercise Intensity Intensity %HRmax %HRR %VO2max RPE

or VO2R Very light <50 <20 <30 <10 (1) Light 50-63 20-39 30-49 10-11 (2) Moderate 64-76 40-59 50-65 12-13 (3-4) Hard (vigorous) 77-94 60-85 66-85 14-16 (5-6) Very hard >94 >85 >85 >16 (7-9) Maximal 100 100 100 19-20 (10)

Adapted from 7th Edition of ACSM Guidelines for Exercise Testing and Prescription

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“There are no studies available comparing all exercise intensity prescription methods simultaneously. Thus, the various methods described in this chapter to quantify exercise intensity may not necessarily be equivalent to each other.”

ACSM Guidelines 8th edition, pg. 157

HR/VO2 Regression – Direct Method

Exercise Prescription by METs (VO2max Reserve or VO2R)

1 MET = 3.5 ml/kg/min = amount of oxygen the average person consumes at rest.

Someone with a maximal capacity of 10 METs can increase their oxygen consumption 10 times above resting levels.

Exercise Prescription by METs (VO2max Reserve; VO2R)

Target METs = [(max METs - 1 MET) X desired % + 1 MET] Example: Joe has a maximal capacity of 10 METs. Calculate

an exercise prescription corresponding to 60 - 80% of VO2R.

Lower Limit Upper Limit Maximal METs 10 10 Resting METs - 1 - 1 MET reserve 9 9 Desired % x .60 x .80

5.4 7.2 Resting METs + 1 + 1 Target METs 6.4 8.2

Example

Patient 1 Patient 2 Rest: 1 MET Rest: 1 MET Max: 4 METs Max: 10 METs

25% 10% 40% VO2max: 1.6 METs 40% VO2max: 4.0 METs 40% VO2R: 2.2 METs 40% VO2R: 4.6 METs

ActivitiesActivities METsMETs ActivitiesActivities METsMETsArcheryArchery 33--44 Horseshoe pitchingHorseshoe pitching 22--33BackpackingBackpacking 55--1010 Mountain climbingMountain climbing 55--10+10+BadmintonBadminton 44--99 Music playingMusic playing 22--33BasketballBasketball 77--12+12+ Paddleball, racquetballPaddleball, racquetball 88--1212

nonnon--gamegame 33--99 Rope jumping, 60Rope jumping, 60--80/min80/min 99BilliardsBilliards 22--33 120120--140/min140/min 1111--1212BowlingBowling 22--44 Running Running 12 min/mile12 min/mile 8.78.7Canoeing, rowingCanoeing, rowing 33--88 11 min/mile11 min/mile 9.49.4Conditioning exerciseConditioning exercise 33--8+8+ 10 min/mile10 min/mile 10.210.2Climbing hillsClimbing hills 55--10+10+ 9 min/mile9 min/mile 11.211.2Cycling, pleasureCycling, pleasure 33--8+8+ 8 min/mile8 min/mile 12.512.5

10 mph10 mph 77 7 min/mile7 min/mile 14.114.1Dancing, socialDancing, social 44--77 SailingSailing 22--55

aerobicaerobic 66--99 ShuffleboardShuffleboard 22--33Fishing, bankFishing, bank 22--44 Skating, ice & rollerSkating, ice & roller 55--88

wadingwading 55--66 Skiing, downhillSkiing, downhill 55--88Football, touchFootball, touch 66--1010 crosscross--countrycountry 66--12+12+Golf, power cartGolf, power cart 22--33 waterwater 55--77

walking with bagwalking with bag 44--77 Stair climbingStair climbing 44--88HikingHiking 33--77 SwimmingSwimming 44--8+8+Horseback riding, walkHorseback riding, walk 2+2+ Table tennisTable tennis 44--9+9+

trottrot 6+6+ TennisTennis 44--9+9+gallopgallop 8+8+ VolleyballVolleyball 33--66

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ACSM Compendium of Physical Activities

Heart Rate Methods Heart Rate Reserve (Karvonen) THR = [(max HR - rest HR) X desired % + rest HR]

Lower Limit Upper Limit Maximal heart rate 180 180 Resting heart rate - 60 - 60 Heart rate reserve 120 120 Desired % X .60 X .80 72 96 Resting heart rate + 60 + 60 132 156

Heart Rate Methods % HR max % HR max - - usually underestimates Karvonen method by usually underestimates Karvonen method by 5 5 - - 15%; therefore we usually adjust percentages up by this 20%; therefore we usually adjust percentages up by this amount (i.e. use 60 amount (i.e. use - - 90% vs 40 90% vs 40 - - 85%) 85%)

180 x .60 = 108 180 x .60 = 108 180 x .70 = 126 180 x .70 = 126 180 x .80 = 144 180 x .80 = 144 180 x .85 = 153 180 x .85 = 153

% Karvonen % Karvonen % HR max % HR max 40 40 55 60 45 45 62 50 50 65 55 55 67 60 60 70 70 65 65 75 75 70 70 80 80 75 75 82 82 80 80 85 85 85 85 90 90

Intensity Violators

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Signs and Symptoms Below Which an Upper Limit for Exercise Intensity Should be Set

•  Angina •  Drop in SBP •  Significant ST depression on previous GXT •  Increased frequency of ventricular ectopy •  Onset of heart blocks (e.g., BBBs, 2º or 3º AV

block) •  Other signs/symptoms of intolerance to

exercise (e.g., extreme SOB) **Exercise heart rate should be set at least 10 bpm below the HR associated with any of the above criteria

Problems with using HR methods: 1. Maximal HR is usually estimated •  220 – age or 206.9 - .67 (age); SD = + 10-12 bpm

If you don’t have a maximal exercise test on someone, you have no idea what their maximal heart rate is, especially if they are older, have disease, and are on medications. Thus, do not use predicted HRmax for exercise prescription!

2.  People goof when taking their pulse 3. Normal day-to-day variability

•  Heat, cold, altitude, illness, excitement, timing of meds, etc.

4. HR/VO2 relationship is different for different modalities

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5.  Even though you may calculate the same exercise HRs for two people (e.g., 50-70% of HR reserve), achieving that prescription may be more (or less) physiologically taxing to individual patients based upon differences in their anaerobic threshold (AT).

What does this have to do with anything?

2 studies: Katch et al., 1978;

Dwyer et al., 1994

•  At 55% of HR reserve, 50% of cardiac patients were above their anaerobic threshold and 50% were below

Aerobic

Anaerobic

50-70% HRR

50-70% HRR

What about Resting HR + 20 bpm? Wake Forest Group

•  11 cardiac rehab patients

•  4 were < 40% of VO2max

•  6 were within 40-60% of VO2max

•  1 was > 60% VO2max

•  range was 25-65% of VO2max

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Subjective Methods

•  Ratings of Perceived Exertion (RPE)

•  Talk Test

Surveys have found that ~ 60% of exercisers prefer subjective methods to guide their exercise program.

Perceived exertion: A note on history and methods

Gunnar A. V. Borg MSSE, 1973

“There are two ordinary things in a man’s life that make his heart beat faster: walking up stairs and watching pretty girls.”

RPE Method (Borg Scales)

6 - 20 Scale 1 - 10 Scale 6 0 7 Very, very light 0.5 Extremely weak 8 1 Very weak 9 Very light 2 Weak 10 3 Moderate 11 Fairly light 4 12 5 Strong 13 Somewhat hard 6 14 7 Very strong 15 Hard 8 16 9 17 Very hard 10 Very, very strong 18 • Maximal 19 Very, very hard 20

•  11 - 13 (3-4) moderate intensity = 40 - 60% HR reserve •  14 - 16 (4-6) high intensity = 60 - 85% HR reserve

6 - 20 Scale 0 - 10 Scale 6 0 7 Very, very light 0.5 Extremely weak 8 1 Very weak 9 Very light 2 Weak 10 3 Moderate 11 Fairly light 4 12 5 Strong 13 Somewhat hard 6 14 7 Very strong 15 Hard 8 16 9 17 Very hard 10 Very, very strong 18 • Maximal 19 Very, very hard 20

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METs

HR

No BB

BB 8 (1)

10 (2) 13 (3)

17 (7) 19 (9)

Problems with using RPE: •  People get distracted (not clued in)

•  Group setting – compare themselves to others

•  Assumes steady-state exercise

•  Some people just don’t get it!!!!

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•  73 year-old woman

•  Exercise HRs: 70-80 bpm

•  ~ 40-50% of HRmax

•  RPE = 17 (very hard)

Gloria

•  74 year-old man

•  Exercise HRs: 125-140 bpm

•  75-90% of HRmax

•  RPE = 10 (fairly light)

Ron

Aerobic Exercise Intensity Assessment and Prescription in Cardiac Rehabilitation

JCRP, 32: 327-350, 2012 •  Joint Position Statement of :

– AACVPR – CACR – EACPR

“the joint statement provides evidence-based indication for a shift from “range-based” to a “threshold-based” aerobic exercise intensity prescription”

Domains of Exercise Intensity

•  Light to Moderate – Below VT1, > 30 minutes

•  Moderate to High – Between VT1 and VT2, 20-30 minutes

•  High to Severe – Above VT2, 3-20 minutes

•  Severe to Extreme – Above VT2, < 3 minutes

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Beale et al., Br. J. Cardiol, 17(3): 133-137, 2010

A Comparison of Conventional Versus Anaerobic Threshold Exercise

Prescription Methods in Subjects with Left Ventricular Dysfunction

Normandin et al., JCR, 13: 110-116, 1993

•  Ascending Aortic Blood Flow Velocity (AABV) and Peak Acceleration (PA) via Doppler

•  AT via VE vs. VCO2 curve (VT1) •  Ex Rx using 50-75% HRmax , 60-80% HRR,

and 57-78% peak VO2

•  When using conventional methods of exercise prescription, 50% of subjects with LVD had significant decreases in PA and AABV above AT.

•  None of the subjects showed a decrease in AABV or PA below AT.

•  Similarly, in our lab we showed that in subjects who had exertional ishemia, 18/19 subjects were below the ischemic threshold at VT1.

One size fits NONE!

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