The use of ratings of perceived exertion to indicate appropriate exercise intensities in cardiac rehabilitation

Purpose: The objective of the study was to examine the extent that ratings of perceived exertion(RPE) can be used to predict physiological and clinical responses to exercise in post myocardial infarction patients(PMIP).This may enable appropriate exercise intensities to be recommended.Methods: Forty-six male recent PMIP with beta block therapy(aged 60.9±7.5 years) and 55 male recent PMIP without beta blockade therapy(aged 63.6±7.3 years) performed a graded exercise test on a motorized treadmill until volitional cessation or reaching any of the American College of Sports Medicine(ACSM) criteria.Oxygen uptake(VO2) and volume of expired gas(VO2) were measured every 30 seconds during the exercise.Heart rate(HR),blood lactate(BL) and ratings of perceived exertion(RPE) were recorded every three minutes,and a 12 lead electrocardiogram was monitored continuously.Results: The results showed that there was a non-significant difference between the two groups in VO2,BL,VE and ST segment depression in relation to the RPE scale.(P0.05).However a significant difference in HR was observed between the two groups throughout the exercise test(P0.01).An RPE level of 13 can be regarded as the transfer point from aerobic to anaerobic metabolism for the patients both with and without beta blockade therapy.Conclusion: Based on above evidence,it is recommended that during cardiac rehabilitation PMIP should not increase exercise intensity further when it feels 'somewhat hard'.