Modeling Intermittent Running from a Single-visit Field Test.

This study assessed whether the distance-time relationship could be modeled to predict time to exhaustion (TTE) during intermittent running. 13 male distance runners (age: 33±14 years) completed a field test and 3 interval tests on an outdoor 400?m athletic track. Field-tests involved trials over 3?600?m, 2?400?m and 1?200?m with a 30-min rest between each run. Interval tests consisted of: 1?000?m at 107% of CS with 200?m at 95% CS; 600?m at 110% of CS with 200?m at 90% CS; 200?m at 150% of CS with 200?m at 80% CS. Interval sessions were separated by 24?h recovery. Field-test CS and D' were applied to linear and non-linear models to estimate the point of interval session termination. Actual and predicted TTE using the linear model were not significantly different in the 1?000?m and 600?m trials. Actual TTE was significantly lower (P=0.01) than predicted TTE in the 200?m trial. Typical error was high across the trials (range 334-1?709?s). The mean balance of D' remaining at interval session termination was significantly lower when estimated from the non-linear model (-21.2 vs. 13.4?m, P<0.01), however no closer to zero than the linear model. Neither the linear or non-linear model could closely predict TTE during intermittent running.