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The work rate corresponding to ventilatory threshold during steady-state and ramp exercise
Oliver Faude1, Tim Meyer, Wilfried Kindermann
1Institute of Sports and Preventive Medicine, University of Saarland, Faculty of Clinical Medicine, 66041 Saarbrücken, Germany.
International Journal of Sports Physiology and Performance
|January 1, 2009
Summary
The constant 45-second time delay used to calculate work rate at ventilatory threshold during ramp exercise is inaccurate. A steady-state test is recommended for precise determination of work rate at ventilatory threshold for training guidelines.
Area of Science:
- Exercise Physiology
- Sports Science
- Cardiorespiratory Fitness
Background:
- The ventilatory threshold (VT) indicates a crucial intensity for endurance training.
- Accurate determination of the work rate (WR) at VT is essential for effective training prescription.
- Current methods using a fixed VO(2) time delay during ramp exercise may lead to inaccuracies.
Purpose of the Study:
- To re-evaluate the temporal relationship between oxygen consumption (VO(2)) and work rate (WR) at the ventilatory threshold (VT).
- To investigate the accuracy of the traditional 45-second time delay (t(d)) in estimating WR at VT during incremental ramp exercise.
Main Methods:
- 20 subjects with high cardiorespiratory fitness performed incremental ramp and steady-state exercise tests.
- Ventilatory threshold (VT) was determined during ramp exercise.
- Work rate (WR) and heart rate (HR) differences at VT were calculated between ramp and steady-state tests (WR(diff), HR(diff)).
- The time delay (t(d)) corresponding to WR(diff) during ramp exercise was analyzed.
Main Results:
- The mean time delay (t(d)) was significantly longer (85 ± 26 seconds) than the traditional 45 seconds.
- Mean WR difference (WR(diff)) was 45 ± 12 W, with wide individual ranges.
- Limits of agreement for WR at VT between ramp and steady-state tests were ± 24 W.
- No significant correlation was found between t(d), WR(diff), or HR(diff) and endurance capacity or ramp increment.
Conclusions:
- The wide variability in time delay and work rate differences highlights the inaccuracy of using a constant time delay for estimating WR at VT from ramp tests.
- Individualized assessment is crucial, and a steady-state test is recommended for precise determination of WR at VT.
- Current findings challenge the universal application of the 45-second time delay in exercise prescription.
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