Article

Exercise prescription based on percentage of peak exercise variables
has many limitations in patients taking beta-blockers. The aim of this study was
to evaluate efficacy and safety of a training protocol based on the rating of
perceived exercise (RPE) in patients taking beta-blockers after cardiac surgical
revascularization. DESIGN AND METHODS: 71 patients treated with beta-blockers
after recent coronary artery bypass grafting were randomly allocated to two
different programmes with training intensity adjusted to keep heart rate close to
first ventilatory threshold (36 subjects, AeT group) or RPE between grades 4 and
5 of 10-point category-ratio BORG scale (35 subjects, RPE group). RESULTS: In the
RPE group, mean training workloads and heart rate values were significantly
higher than in the AeT group; during the last week of the programme, six RPE
patients were training very close to anaerobic threshold. Aerobic peak capacity
increased similarly in the two groups. Considering the potential effects on
training intensity of prescriptions based on percentages of peak exercise
variables, we found that only percentage heart rate reserve and peak workload
methods were reliable in defining a safe upper limit of training intensity, with
values of 50% and 65% respectively. CONCLUSIONS: Self-regulation of exercise
training intensity between grades 4 and 5 of the 10-point category-ratio BORG
scale is effective but may promote overtraining in some patients without
significant functional advantages. For these reasons, RPE method should be
integrated with objective indices based on percentage of heart rate reserve or of
peak workload.

Langue : ANGLAIS