**5. Conclusions**

A 5 × 200-m progressively increasing speed test and the determination of V4 calculated by interpolation of a second-order polynomial function fitted to the swimming speed vs. lactate concentration data seem to provide physiological and biomechanical variables with a large interindividual variability. It should be expected that swimmers will adjust their mechanics at increased metabolic cost to maintain the required speed during an intermittent training set including 400-m repetitions. Specifically, increased SR and decreased SL may be observed when swimmers aim to maintain speed during a 5 × 400-m intermittent training set. It seems that swimmers change the arm stroke profile in aiming to maintain the required speed during a long-duration constant intensity set. The large interindividual variation between swimmers, possibly because of their specialty or the characteristics (i.e., number of repetitions, interval time, distance) of the test used to calculate the required parameters, should be considered. Coaches should be aware that prescribed physiological or mechanical parameters may be altered when swimmers follow a training pace corresponding to V4 during aerobic endurance training.

**Author Contributions:** Conceptualization, A.G.T. and G.G.A.; methodology, A.G.T., P.G.B., G.G.A.; software, G.G.A.; validation, A.G.T. and P.G.B.; formal analysis, P.G.B.; investigation, G.G.A., I.S.N. and I.M.; resources, A.G.T.; data curation G.G.A.; writing – original draft preparation, G.G.A.; writing—review and editing A.G.T.; visualization, P.G.B.; supervision, A.G.T.; project administration, A.G.T. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** The authors would like to thank the swimmers for their participation in the study.

**Conflicts of Interest:** The authors declare no conflict of interest, financial or otherwise.
