Introduction. Swimming performance depends on the swimmer’s capacity to generate mechanical power and resist fatigue. As short intense exercise (up to 1 min in duration) depends heavily on anaerobic energy release, glycolytic contribution seems fundamental for performing the 50 m and 100 m swimming events. Swimming velocity is also highly dependent on swimmers’ technique, which could be assessed with stroke frequency (SR) and stroke length (SL). Aim of Study. The study aimed to analyse changes of metabolic and technical parameters in swimmers performing a maximal 100-m all-out front crawl. Material and Methods. Seven well-trained male swimmers (51.79+ 1.1 s at 100 m freestyle), performed an 100-m all-out front crawl, with intermediate velocity, SR, and SL assessed at each 25 m of the covered test distance. To estimate changes in blood lactate concentrations ([La–]), the blood lactate increasing speed (BLIS) methodology was used, with swimmers performing 25, 50 and 75 m front crawl bouts (controlled with a visual pacer) at the previously assessed velocities in each split of the 100 m test. [La–] were assessed before and immediately after each trial (until reaching the peak [La–]), with BLIS determined with the time rate of net [La–] per split. SR and SL were assessed using a video camera and a chronometer. Means and SD, Spearman’s rank correlation coefficient and ANOVA for repeated measures were used (p < 0.05) for statistical analysis. Results. The average velocity of the 100 m test was 1.89 ± 0.15 m·s–1, decreasing during the first three laps (and increasing in the last 25 m), concurrently with an increase in SR and a decrease in SL. [La–]increased throughout the test (to 15.01 ± 1.42 mmol·l–1), and BLIS diminished during the first three laps, while increasing during the last one. Conclusions. Glycolytic power determines the first 25 m lap of a maximal 100 m front crawl effort, causing fatigue effects measured with simple biomechanical parameters. A volitive effect of metabolic pathways can be observed in the last 25 m