**5. Conclusions**

This study suggests that the PNI condition may have a positive e ffect on sports training. However, there are limitations to this study. We conducted the experiments on 10 elite swimmers, but it is necessary to expand the sample size in order to generalize this study. It is thus necessary that future studies be conducted with more participants. In addition, although this study conducted the experiment twice in an environment in which the athletes were randomly switched, it is recognized that emotions may change depending on the condition of the athlete on that day. Therefore, it is suggested that conducting a longitudinal experiment on the same participants might shed more accurate findings on the matter.

**Author Contributions:** Conceptualization, G.H. and H.M.; methodology, G.H., H.M., and T.T.; investigation, M.M., H.F., and T.T.; writing—original draft preparation, G.H.; writing—review and editing, H.M. and T.T. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Sharp Corporation.

**Conflicts of Interest:** This study was funded by Sharp Corporation. M.M. and H.F. are employees of Sharp Corporation.
