A greater volume of HIIT may be needed to maximize the training response for all individuals.

Although maximal oxygen uptake (VO max) has been measured for almost 100 years, it is unknown when 'true' VO max is attained. Primary (the VO plateau) and secondary criteria are used to confirm VO max incidence, but frequency of the VO plateau varies, and secondary criteria are relatively invalid. The verification test (VER) seems to elicit similar estimates of VO max versus the incremental value (INC), yet existing data are limited by small populations and use of inadequate criteria to confirm 'true' VO max. We investigated the efficacy of VER by analysing data from 109 participants who underwent INC followed by VER at 105% or 110% of peak power output (PPO). Differences in VO max between VER and INC were analysed, and intraclass correlation coefficient (ICC), standard error of the mean (SEM) and minimum difference (MD) were computed. Results showed that VO max was significantly higher (2%, P<0·05) in INC versus VER, VO max was highly related between protocols (ICC = 0·99) and SEM and MD were low. However, 11% of participants did not reveal 'true' VO max as the verification value was higher than INC by 3·0% - 3·3%. Fitness level altered the difference in VO max between INC and VER in study one, as lower fitness individuals showed a larger difference in VO max between protocols, although gender did not affect the difference in VO max between protocols. Our data show that VER does not verify 'true' VO max in all individuals, which may be related to their fitness level.

No abstract

Background: There is individual responsiveness to exercise training as not all individuals experience increases in maximal oxygen uptake (VO2max), which does not benefit health status considering the association between VO2max and mortality. Approximately 50% of the training response is genetic, with the other 50% accounted for by variations in dietary intake, sleep, recovery, and the metabolic stress of training. This study examined if the blood lactate (BLa) response to high intensity interval training (HIIT) as well as habitual dietary intake and sleep duration are associated with the resultant change in VO2max (ΔVO2max). Methods: Fourteen individuals (age and VO2max = 27 ± 8 years and 38 ± 4 mL/kg/min, respectively) performed nine sessions of HIIT at 130% ventilatory threshold. BLa was measured during the first and last session of training. In addition, sleep duration and energy intake were assessed. Results: Data showed that VO2max increased with HIIT (p = 0.007). No associations occurred between ΔVO2max and BLa (r = 0.44, p = 0.10), energy intake (r = 0.38, p = 0.18), or sleep duration (r = 0.14, p = 0.62). However, there was a significant association between training heart rate (HR) and ΔVO2max (r = 0.62, p = 0.02). Conclusions: When HIIT is prescribed according to a metabolic threshold, energy intake, sleep status, and BLa do not predict ΔVO2max, yet the HR response to training is associated with the ΔVO2max.