Age-related heart rate thresholds to optimize aerobic training in cardiac rehabilitation

Abstract

The purpose of the study was to determine a safe and effective aerobic training threshold based on heart rate for post-myocardial infarction patients which would be simple to administer. This was required because of the concerns about using existing age-related formulae, which were inappropriate for this clinical group.

Thirty male recent post-myocardial infarction patients with beta blockade therapy (aged 60±8.9 years) and 40 male recent post-myocardial infarction patients without beta blockade therapy (aged 63.4±8.2 years) performed a graded exercise test (modified Bruce protocol) on a motorized treadmill until volitional cessation or reaching any of the American College of Sports Medicine criteria.

Ratings of perceived exertion, blood lactate, oxygen uptake, angina score, dyspnoea score and blood pressure were recorded every 3 min during the exercise. Oxygen uptake, volume of expired gas and heart rate were recorded every 30 s during the exercise and a 12-lead electrocardiograph was monitored continuously.

The results showed that the patients did not achieve the age-related maximum heart rates predicted from 220-age, showing early signs of myocardial ischaemia at about 90% of their peak heart rate. Patients using beta blockade had a significantly lower (P<0.01) heart rate both a rest and at peak work rate compared with the non-blockade group.

Peak heart rate can be predicted from age for the two distinct groups and this enabled the optimal aerobic training thresholds to be determined for post-myocardial infarction patients aged 50–70 years separately for those who do or do not require beta-blockade therapy.