HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

Electronic Letters to:

ARTICLES: Bryan J. Taylor and Lee M. Romer Effect of expiratory muscle fatigue on exercise tolerance and locomotor muscle fatigue in healthy humans J Appl Physiol 2008; 104: 1442-1451 [Abstract] [Full text] [PDF]

eLetters: Submit a response to this article

Electronic letters published:

Time to exhaustion tests vs time trials

Samuele M Marcora   (19 March 2008)

Time to exhaustion tests vs time trials 19 March 2008
Samuele M Marcora, Senior Lecturer in Exercise Physiology School of Sport, Health and Exercise Sciences, Bangor University, Wales, UK Send letter to journal: Re: Time to exhaustion tests vs time trials s.m.marcora{at}bangor.ac.uk Samuele M Marcora	In their paper, Taylor and Romer (1) spend a considerable part of the Discussion to justify the choice to use a time to exhaustion test (TTE) as their measure of endurance performance. This was probably prompted by reviewers' concerns about the high variability of TTEs (CV 10-30%) compared to time trials (TTs) (CV 1-3%) (eg. ref. 2). Taylor and Romer defended well their choice. However, we would like to add some additional considerations. First of all, all scientists using inferential statistics should know that no matter how large is the variability of a measure, this variability is included in the error variance of both t-tests and ANOVAs. Therefore, any statistically significant (i.e. systematic) difference between groups/conditions CAN NOT be due to the high coefficient of variation (CV) of the test used to measure endurance performance. Indeeed, by definition, the CV is random variance both above and below the mean, and no systematic difference between two or more means can occur by chance. Secondly, we have demonstrated experimentally (3) that test sensitivity (i.e., the "signal-to-noise ratio") is similar between TTs and TTEs despite considerable differences in CV. This is because the change in performance induced by an intervention is much larger when measured with TTEs compared to TTs. Therefore, the large signal compensates for the large noise of TTEs resulting in similar if not better sensitivity compared to TTs. Therefore, TTEs are as good as TTs in detecting changes in endurance performance due to experimental interventions. The choice between these two tests modalities should be based on the purpose of the study. Time trials are the obvious choice for studies on the effect of self-selected pacing on performance, whereas TTEs provide better control of workload for studies of physiological determinants of endurance performance. 1) Taylor BJ, Romer LM. Effect of expiratory muscle fatigue on exercise tolerance and locomotor muscle fatigue in healthy humans. J Appl Physiol. 2008 2) Jeukendrup A, Saris WH, Brouns F, Kester AD. A new validated endurance performance test. Med Sci Sports Exerc. 1996; 28(2): 266–70. 3) Amann M, Hopkins WG, Marcora SM. Similar Sensitivity of Time to Exhaustion and Time-Trial Time to Changes in Endurance. Med Sci Sports Exerc. 2008; 40(3): 574–8.