Background A everyday method for ...

Background

A everyday method for quickly deriving an estimate of a person's maximal heart rate (MHR) is by the agency of using the formula 220 - age in years, also known as the age adjusted maximum heart rate (AAMHR) formula. While various authors have commended other more specific regression equations as better predictors of MHR for exercise prescription, the AAMHR formula remains the principally widely promoted and used calculation for getting a quick, cragged estimate of the MHR. The approveed target heart rate range for intensity of aerobic exercise is 60-90% of the maximal heart rate. The AAMHR formula may be utilized when prescribing exercise for healthy individuals. However, it may be inappropriate and uniform dangerous to apply it to individuals with clinical impairments. In of that kind cases, exercise prescription should be based forward a more appropriate method similar as data gathered from a graded exercise criterion or conservative estimates by a capable clinician combined with clinical monitoring.

At the conclusion of this reproof participants should be able to:

1 describe physiological command mechanisms of heart rate,

2 list factors effecting maximal heart rate,

3 relate the origins of the AAMHR formula,

4 discuss the limitations of AAMHR for exercise prescription for apparently healthy [i]role[/i]s

5. list and discuss clinical conditions effecting heart rate rejoinder to exercise,

6. list pharmacological agents effecting heart rate replication to exercise, and

7 describe appropriate systems of defining and monitoring exercise intensity of bodily forms with clinical conditions.

Outline

1.Case examples (from actual patient records) demonstrating inappropriate use of AAMHR in clinical settings to introduce the topic

2 Physiological govern mechanisms of heart rate

* Characteristics of cardiac muscle tissue

* Neural check of heart function

- autonomic tone

- central and peripheral reflexe

* Other factors

- hormonal factors - thyroid, shooting hormone, cortisol

* The intrinsic heart rate,1,2

* Heart rate answer to exercise

3. History of the unfolding of the AAMHR formula

* First prompted by Samuel Fox and William Haskell based forward review of maximal exercise touchstone data of various studies.3

* First cited on Fox in 1971(4)

4 Factors influencing maximal heart rate

* Age5-17

* Gender111617

* flush of fitnesse8,18,19

* prototype of exercise16,17

* Cardiovascular disease7,15,20

- chronotropic incompetence

* Resting heart rate13,21,22

* corpse weight21,23

* Bedrest24

* Altitude25,26

* constant maximal exertion

* rule of heart rate recording

5 Alternate prediction formulas for maximal heart rate8,10,16,17,23,27

6 Limitations of AAMHR for exercise prescription for apparently healthy individuals.

* Poor relationship of maximal heart rate to age

- standard error of the estimate: 10-25 bpm1728

- correlation coefficients -04(28)

- 95% confidence interval = 40 - 60 bpm111621

>> GREAT INTERINDIVIDUAL VARIABILITY

>>> INDISCRIMINANT USE OF AGE PREDICTED MAXIMAL HEART RATE IN MAKING EXERCISE PRESCRIPTIONS OR IN SETTING GOALS FOR TREADMILL PERFORMANCE SHOULD BE AVOIDED11,21,28

7 Considerations regarding the use of AAMHR formula for exercise prescription for clinical populations.

* Cardiovascular disease

- impaired myocardial function

- atrioventricular conduction stop ups

- effects of denervation - cardiac transplantation

* general intents of pharmacological agents on heart rate reply to exercise

- beta blockers29

- calcium-channel blocker

* Dysautonomia owing to neurological deficits - diabetes30

- multiple sclerosis31-33

- paraplegia34

- Parkinson's disease 3435

* Below normal maximal heart rates observ in various other patient populations

- mental retardation27,34

- post-polio syndrome34

- neuromuscular disease34

8 Appropriate way s of defining and monitoring exercise intensity of bodily forms with clinical conditions34,36,37

* Maximal exercise testing

* Submaximal exercise testing

* Rating of perceived exertion

Estimated exercise intensity based upon clinical judgment, combined with clinical monitoring -- the "Art of Exercise Prescription"

9 Interactive case close attention discussion of appropriate exercise prescription and appropriate monitoring of exercise intensity of [i]role[/i]s with clinical conditions

* BK (78) - senior athlete

* DP (38) - DM sign I and multiple sclerosis

* J (54) - heart transplant

Reference

1 De Marneffe M et al. Variations of normal sinus node function in relation to age: part of autonomic influence. European Heart]. 1986;7:662-672

2 Jose AD, RR Taylor. Autonomic blockade on propanolol and atropine to close attention intrinsic myocardial function in man. J Clin Invest. 1969;48:2019-2031

3 Kolata G "Maximum" heart rate theory is challenged. The of the present day York Times. 2001:1-4.

4 Fox s Naughton J, Haskell W. Physical activity and the prevention of coronary heart disease. Ann Clin Re 1971;3:404-432

5 Astrand I. Aerobic work capacity in men and women with special hint to age. Acta Physiologica Scandinavica. 1960;49(suppl 169):1-82

6 Kostis JB et al. The issue of age on heart rate in make submissives free of heart disease: studies on ambulatory electrocardiography and maximal exercise stres exhibition Circulation. 1982;65:141-145.