Time to Exhaustion at Traditional Physiological Indicators in Runners: Between-Subject and Between-Day Variability.

Mean time to exhaustion at VO2max, RCP, and MLSS intensities were approximately 3.5 minutes, 11 minutes, and 57 minutes, respectively.

• TTE at VO2max was 03:38 (±00:40) mm:ss
• TTE at RCP was 10:58 (±02:59) mm:ss
• TTE at MLSS was 56:42 (±13:02) mm:ss
• 13 male athletes participated with a mean VO2max of 60.2 (4.2) mL·kg-1·min-1
• Each participant performed 2 TTE tests on different occasions at the speed corresponding to each indicator

Between-subject variability in TTE was moderate across all three physiological intensity markers.

• Coefficient of variation for between-subject variability was 18.3% at VO2max intensity
• Coefficient of variation was 27.3% at RCP intensity
• Coefficient of variation was 23.0% at MLSS intensity

TTE at each physiological indicator showed no significant association with other fitness indicators or with VO2max.

• No significant associations were found between TTEs and the speed at which each intensity occurred
• No significant associations were found between TTEs and VO2max
• All correlation coefficients were r < .1 with P > 0.2
• This suggests TTE is independent of traditional physiological performance indicators

Within-subject (between-day) reliability of TTE was high at all three physiological intensity markers.

• Coefficient of variation for within-subject reliability was 4.4% at VO2max intensity
• Coefficient of variation was 4.8% at RCP intensity
• Coefficient of variation was 6.4% at MLSS intensity
• Intraclass correlation coefficients were .94 at VO2max, .97 at RCP, and .90 at MLSS

Blood lactate, heart rate, and perceptual responses were measured during TTE tests to characterize the physiological demands at each intensity.

• Measurements were taken during both TTE test occasions at each intensity
• Three intensity markers assessed were VO2max, respiratory compensation point (RCP), and maximal lactate steady state (MLSS)
• Testing was conducted on a treadmill
• Sample consisted of 13 male athletes

The authors concluded that TTE tests could be used for performance monitoring and training prescription purposes.

• The recommendation is based on the high within-subject reliability observed across all three intensity markers
• The independence of TTE from other traditional physiological indicators supports its use as a distinct performance measure
• TTE tests at VO2max, RCP, and MLSS are described as suitable tools for these applied purposes