The aim of the study was to investigate the accuracy of the 20 m shuttle run test (20mSRT) for the prescription of high-intensity interval training (HIIT) and to examine the appropriate intensity, prescribed by the 20mSRT end-test speed, for the execution of HIIT. Twenty physical education students (age: 22.4 ± 0.8 years, body height: 175.7 ± 8.9 cm, body weight: 73.8 ± 13.4 kg) participated in the study. On two separate occasions the participants were first tested with a maximal incremental exercise test and the 20mSRT. On another two occasions they were required to perform a 10-minute HIIT session comprised of 15-s runs interspersed with 15-s passive recovery. The intensities of the HIIT sessions were either 100% (T100%) or 110% (T110%) of the end-test speed reached in the 20mSRT. Mean oxygen uptake (VO2) (84.4 ± 5.5% vs 77.8 ± 6.9% of VO2max), mean heart rate (HR) (93 ± 2.8% vs 87.6 ± 4.6% of HRmax), blood lactate concentration (12.6 ± 2.1 vs 5.4 ± 2.6 mmol/l), and ratings of perceived exertion (9.5 ± 0.5 vs 6.7 ± 1) were all significantly (p<.01) higher during T110% vs T100%. The percentage of the total exercise time spent ≥ 90% VO2max (37.6 ± 25.3 vs 18.6 ± 18.0%, p<.05) and ≥ 90% HRmax (73.9 ± 17.7% vs 37.5 ± 33.3, p<.001) were also significantly higher during T110%. The mean VO2 and HR coefficient of variation during T110% were 6.5 and 3%, respectively. The cardiorespiratory, metabolic, and perceptual responses to T110% were reflective of the responses typical for HIIT, while T100% induced insufficient physiological stress to enable optimal cardiorespiratory adaptation. Therefore, the intensity of 110% 20mSRT is preferable for inducing the appropriate acute physiological responses and the 20mSRT can be used to accurately prescribe HIIT.

The purpose of the study was to compare the degree of intersubject variability in the cardiorespiratory, metabolic, and perceptual responses to high‐intensity interval training (HIIT) prescribed based on the relative anaerobic speed reserve (ASR) or maximal aerobic speed (MAS) and to identify the optimal % ASR for execution of such HIIT. Seventeen male physical education students (age: 23.6 ± 1.1 years, height: 180.2 ± 5.9, body mass: 78.3 ± 8.1 kg; % body fat: 14.3 ± 2.7%) volunteered to execute three randomly scheduled 10‐min HIIT exercises at 110% vVO2max, Δ15% ASR, or Δ25% ASR. Analysis of variance for repeated measures and the least significant difference post‐hoc test were used to compare the physiological responses and the mean of individual residuals between the training sessions. The coefficients of variation (CV) of time spent ≥90% of maximal oxygen uptake (VO2max) and maximal heart rate (HRmax), peak VO2, mean VO2, peak HR, mean HR, blood lactate [La], and rating of perceived exertion (RPE) were 48.7%, 35.9%, 9.3%, 7%, 3.5%, 4.8%, 32%, and 16.9% during 110% vVO2max, 47.2%, 31%, 7.5%, 6.7%, 3.9%, 4.6%, 24.2%, and 14.6% during Δ15% ASR, and 48.1%, 31.5%, 7.6%, 8.4%, 3.6%, 4.1%, 20.2%, and 3.4% during Δ25% ASR session, respectively. Only the residuals in RPE were significantly (p < 0.001) higher in 110% vVO2max and Δ15% ASR in comparison to Δ25% ASR. Time spent ≥90% HRmax/VO2max was maximized during Δ15% ASR session, albeit this was not significantly different from other sessions. The ASR‐based method leads to reduced CVs of physiological and perceptual responses during 10‐min HIIT; however, only reductions in [La] and RPE may be considered practically meaningful. Practitioners can use vVO2max for prescription of 10‐min HIIT session comprised of 15‐s work and passive recovery intervals.