Determination of training intensity in myocardial infarction survivors treated by beta--blockers
- Oddělení funkčního vyšetřování, Fakultní nemocnice Brno-Bohunice, Brno, Česká republika
Aim:
The aim of our study was to answer the following questions: is it possible to determine, in beta-blocker-treated MI patients, training intensity by their heart rate? What are suitable alternatives for determining training intensity?
Method:
The group included 112 men and 19 women. The mean ages of men and women were 60.2 ± 8.6 and 58.8 ± 6.1 years, respectively. Eligible were patients after a previous myocardial infarction, treated by beta-blockers. Prior to their inclusion into a rehabilitation program, patients had exercise echocardiography under a standard protocol used in our department. In the same week, patients underwent symptom-limited spiroergometry using the treadmill test. The anaerobic threshold (AT) was determined by the method of non-linear increase in carbon oxide expiration, i. e., V-slope method. Spiroergometry was used to assess exercise tolerance in W/kg, peak heart rate, heart rate at AT, peak oxygen consumption, oxygen consumption at AT, exercise tolerance at AT, percentage of peak oxygen consumption at AT, and percentage peak heart rate at AT. Heart rate at AT was compared with the values of 70% and 80% of heart reserve and 80% of peak heart rate.
Results:
In men, mean heart rate at AT was 104.7 ± 13.3 and corresponded to 81.0 ± 8% of peak oxygen consumption and 87.9 ± 5.6% of peak heart rate. Mean heart rate corresponding to 80% of peak heart rate was 96 ± 13.7, being 103.3 ± 13.1 at 70% of heart reserve and 108 ± 14.4 at 80% of heart rate. Mean heart rate in women at AT was 112.1 ± 16.6 and corresponded to 84.4 ± 12.6% of peak oxygen consumption and 92.2 ± 5.5% of peak heart rate. We demonstrated a close correlation between heart rate at AT and values of 80% of peak heart rate and calculation based on heart reserve. We noted that exercise intensity at AT is within a relatively close range of 1 W/kg.
Conclusion:
We believe that the formula derived from peak heart rate or heart reserve can be used even in beta-blocker-treated MI patients to calculate training-related heart rate. Exercise intensity given in W/kg can also be used as a secondary marker.
Keywords: Myocardial infarction; Beta-blockers; Anaerobic threshold; Training intensity
Published: February 1, 2005 Show citation