| Abstrakt: |
Purpose: Accurate quantification and monitoring of exercise “dose”, described by oxygen consumption (VO2), is necessary for exercise prescription and individualization. However, due to the complexity and elevated cost of direct, gold-standard methods, this is rarely done outside research laboratories. Heart rate-index (HRindex) is a new simple method to estimate VO2in healthy and clinical populations. We tested the performance of HRindexto estimate VO2in diabetic patients during aerobic (AT) and isotonic training (IT). Methods: Data from 12 males (age: 64 ± 5 years; BMI: 26 ± 12) with type 2 diabetes were analysed. VO2and heart rate were measured during one AT and one IT session. Furthermore, VO2was indirectly estimated based on HRindex. Then, the correspondence between measured and estimated VO2was evaluated by two-way RM-ANOVA, correlation and Bland–Altman analysis. Results: Estimated average VO2values during AT (1292 ± 366 ml/min) were not different from (p= 0.243) and highly correlated with (r= 0.87, p< 0.001) the measured values (1369 ± 417 ml/min), with a small bias and imprecision. Conversely during IT, HRindexoverestimated VO2compared to the actual measures (1048 ± 404 vs 667 ± 230 ml/min, p≤ 0.001) and only a moderate correlation was found between values (r= 0.43, p≤ 0.001), with a large bias and imprecision. Conclusion: VO2of aerobic exercises can be accurately estimated in diabetes patients using HRindex. During isotonic exercise, this method is not recommended for monitoring metabolic intensity due to large overestimation and imprecision. In aerobic exercise, HRindexoffers a simple and valid alternative to the direct VO2determination and may favour the applicability of time-resolved measures of exercise “dose”. |
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