Distance Capacity Above the Critical Speed and Speed Reserves: are they Related?

The aim of this study was to correlate the anaerobic speed reserve and the maximal speed reserve with the distance capacity above the critical speed (<i>D</i>'), derived from four different mathematical models, in a group of endurance runners. Twenty-two runners performed an incremental treadmill test to exhaustion, an all-out 40-m sprint and three time trials (800, 1,500 and 3,000 m) on an outdoor running track to determine an anaerobic speed reserve, a maximal speed reserve and <i>D</i>'. <i>D</i>' was determined using linear distance-time (<i>D</i>'linear <i>d</i>-<i>t</i>), linear velocity-time (<i>D</i>'linear 1/<i>t</i>), 2-parameter hyperbolic (<i>D</i>'2-hyp) and 3-parameter hyperbolic (<i>D</i>'3-hyp) models. A high correlation was observed between the anaerobic speed reserve and <i>D</i>'linear 1/<i>t</i> (<i>r</i>=0.77; <i>p</i><0.001), while moderate correlations were observed between the anaerobic speed reserve and <i>D</i>'linear <i>d</i>-<i>t</i> (<i>r</i>=0.69; <i>p</i><0.001) and <i>D</i>'2-hyp (<i>r</i>=0.63; <i>p</i><0.003). The anaerobic speed reserve was not significantly correlated with <i>D</i>'3-hyp. High correlations were detected between the maximal speed reserve and <i>D</i>'linear 1/<i>t</i>, <i>D</i>'linear <i>d</i>-<i>t</i> and <i>D</i>'2-hyp (<i>r</i>=0.74 to 0.76; <i>p</i><0.001) and a moderate correlation was detected between the maximal speed reserve and <i>D</i>'3-hyp (<i>r</i>=0.58; <i>p</i>=0.01). These moderate- to high correlations with <i>D</i>', especially when derived from models using two parameters, suggest the existence of similar mechanisms underpinning the variables.