Abstract
PurposeTraining intensities are frequently prescribed as relative workloads based on a single reference value (e.g. maximum oxygen uptake). However, exercise-induced physical strain is multifaceted and large interindividual variability in intensity markers has been reported for constant load exercise with standardized relative intensity. This questions the accuracy of (univariate) relative intensities in targeting specific training stimuli. The present trial aims to investigate interindividual variability in the relationship of strain indicators using interpolated performance curves derived from constant load tests at different workloads. This approach enables the prediction of other indicators based on a chosen reference and subsequent comparison of predictive accuracy between group-based and individualized regression models.Methods15 competitive cyclists completed a stepwise incremental cycling test followed by 5 constant load tests with the same absolute workloads as in the stepwise incremental test. The highest of theses workloads which yielded a lactate (BLa) steady state was repeated enabling estimation of intraindividual variability. From constant load tests, the courses of BLa relative to the respective reference value (e.g. %VO2peak) were interpolated by polynomial regression. Variability between individual regression curves was analyzed by mixed modeling. Predictive accuracy was estimated as the sum of squared differences between predicted and observed values.ResultsThe proportion of total variation in the course of BLa relative to the respective reference parameter accounted for by subject identity ranged between 36 and 51%. A significant increase in predictive accuracy was observed for VO2peak and HRmax, respectively, as predicting parameters.ConclusionThese results are in support of a multivariable, individualized approach to intensity prescriptions when aiming at accurately targeted perturbations of homeostasis.
Highlights
The aim of prescribing a specific training intensity is to induce a stimulus for adaptation as precisely targeted and standardized as possible
Training intensities are frequently prescribed as relative workloads based on a single reference value
Exercise-induced physical strain is multifaceted and large interindividual variability in intensity markers has been reported for constant load exercise with standardized relative intensity
Summary
The aim of prescribing a specific training intensity is to induce a stimulus for adaptation as precisely targeted and standardized as possible. Characterizing a state of exercise-induced physical strain intrinsically calls for a multivariate approach Despite this consideration, training intensities are generally prescribed relative to a single reference value mainly for practical reasons. This bases on the assumption that the relationship between different intensity markers is constant e.g. 60% VO2max corresponds to 80% HRmax and 2 mmolÁl-1 blood lactate concentration (BLa) [5]. Markedly heterogeneous BLa and HR responses have been reported for constant load tests at fixed percentages of VO2max [5,6] These results question the assumption of fixed relationships between different intensity domains [1] and cause concern about the performance of a single reference value in terms of accurately standardized training intensities
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