ABSTRACT: Capostagno, B, Lambert, MI, and Lamberts, RP. Analysis of a submaximal cycle test to monitor adaptations to training: Implications for optimizing training prescription. J Strength Cond Res 35(4): 924-930, 2021-The Lamberts and Lambert Submaximal Cycle Test (LSCT) was developed to monitor training adaptation to optimize the training prescription of cyclists. However, it is not known which of the variables within the LSCT are most closely associated with changes in training status. The aim of this study was to retrospectively analyze the LSCT data of cyclists (n = 15) who completed a 2-week high-intensity interval training intervention. The cyclists were retrospectively allocated to 1 of 2 groups based on the change in their 40-km time trial (40-km TT) performance. The "adapters" (n = 7) improved their 40-km TT performance, while the "nonadapters" (n = 8) failed to improve their 40-km TT performance. The variables measured in the LSCT were analyzed to determine which measures tracked the improvements in 40-km TT performance the best. Heart rate recovery increased significantly during the training period in the "adapters" group, but decreased in the "nonadapters" group. Mean power output in stage 2 of the LSCT tended to increase during the high-intensity interval training period in the "adapters" group and was unchanged in the "nonadapters" group. The findings of this study suggest that heart rate recovery and mean power output during stage 2 are the most sensitive markers to track changes in training status within the LSCT.