Objectives To provide an integrative framework of endurance performance, the anaerobic speed reserve (ASR) gained increasing popularity in middle-distance running. The present study investigated athlete profiles and performance predications based on the ASR framework in 400m athletes. Design Descriptive Laboratory Study. Methods Maximal oxygen uptake, lactate threshold (vL4), maximal sprinting speed (MSS), maximal aerobic speed (MAS), and Speed Reserve Ratio (SRR; MSS:MAS) of national level and elite German 400m-sprinters (n=13 females, age [yrs]: 20.8±3.1, personal best (PB400) [s]: 55.1±3.0 & n=5 males, age: 22.8±3.1, PB400: 46.7±1.0) were assessed. A prediction model for 400m performance was computed via stepwise multiple regression. K-means clustering was calculated based on the SRR. Results MSS, MAS and vL4 showed moderate to large negative bivariate correlations with 400m performance (- 0.61<r<- 0.94; p=0.008). Backward stepwise regression revealed MSS and MAS as strong predictors for 400m performance (adjusted R2=0.90, SEE=1.447s [2.6%]). K-means clustering revealed two distinct subgroups along the SRR-continuum (sprint-type: SRR = 1.81; endurance-type: SRR = 1.77). Conclusion MSS and MAS are powerful predictors for 400m performance, with vL4 also being associated with 400m performance. SRR calculation enables a differentiation between 400m sprint-type and endurance-type athletes. The interplay of MSS and MAS enables a broader understanding of the contributing factors to 400m performance. These parameters may support coaches in programming training tailored to individual needs during different training periods.
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