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The delta concept does not effectively normalise exercise responses to exhaustive interval training

Bossi, Arthur, Timmerman, Wouter P., Cole, Diana J., Passfield, Louis, Hopker, James G. (2024) The delta concept does not effectively normalise exercise responses to exhaustive interval training. Journal of Science and Medicine in Sport, . ISSN 1440-2440. (doi:10.1016/j.jsams.2024.07.019) (KAR id:106837)

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https://doi.org/10.1016/j.jsams.2024.07.019

Abstract

Objectives: This study was designed to quantify inter- and intra-individual variability in performance, physiological, and perceptual responses to high-intensity interval training prescribed using the percentage of delta (%Δ) method, in which the gas exchange threshold and maximal oxygen uptake (VȮ 2max) are taken into account to normalise relative exercise intensity.

Design: Repeated-measures, within-subjects design with mixed-effects modelling.

Methods: Eighteen male and four female cyclists (age: 36 ± 12 years, height: 178 ± 10 cm, body mass: 75.2 ± 13.7 kg, V̇O2max: 51.6 ± 5.3 ml·kg−1 ·min−1 ) undertook an incremental test to exhaustion to determine the gas exchange threshold and V̇O2max as prescription benchmarks. On separate occasions, participants then completed four high-intensity interval training sessions of identical intensity (70 %Δ) and format (4-min on, 2- min off); all performed to exhaustion. Acute high-intensity interval training responses were modelled with participant as a random effect to provide estimates of inter- and intra-individual variability.

Results: Greater variability was generally observed at the between- compared with the within-individual level, ranging from 50 % to 89 % and from 11 % to 50 % of the total variability, respectively. For the group mean time to exhaustion of 20.3 min, inter- and intra-individual standard deviations reached 9.3 min (coefficient of variation = 46 %) and 4.5 min (coefficient of variation = 22 %), respectively.

Conclusions: Due to the high variability observed, the %Δ method does not effectively normalise the relative intensity of exhaustive high-intensity interval training across individuals. The generally larger inter- versus intra-individual variability suggests that day-to-day biological fluctuations and/or measurement errors cannot explain the identified shortcoming of the method.

Item Type: Article
DOI/Identification number: 10.1016/j.jsams.2024.07.019
Uncontrolled keywords: Delta concept intensity prescription, normalisation, adaptive variability, individual response, trainability
Subjects: R Medicine > RC Internal medicine > RC1235 Physiology of sports
Divisions: Divisions > Division of Natural Sciences > Sport and Exercise Sciences
Funders: National Council for Scientific and Technological Development (https://ror.org/03swz6y49)
Depositing User: James Hopker
Date Deposited: 09 Aug 2024 16:46 UTC
Last Modified: 03 Oct 2024 14:57 UTC
Resource URI: https://kar.kent.ac.uk/id/eprint/106837 (The current URI for this page, for reference purposes)

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