lactater is released under the MIT licence (see LICENSE).

The dataset `lactate_tests` includes data from two sources, used under the Creative Commons Attribution
4.0 International licence (CC BY 4.0, https://creativecommons.org/licenses/by/4.0/):

* Trinity College Dublin graded exercise test data. Zenodo. doi:10.5281/zenodo.10841412.
* Heuberger JAAC, Gal P, Stuurman FE, et al. Repeatability and predictive value of lactate threshold
  concepts in endurance sports. PLOS ONE 2018;13(11):e0206846. Data on figshare,
  doi:10.6084/m9.figshare.7240571.

Only stage-level intensity, lactate and heart rate, sex and body mass were kept; names, birth dates and
test dates were removed. See data-raw/lactate_tests.R.

The reference percentiles used by `reference_percentiles()` are the supplementary data of the following article,
used under the same licence (CC BY 4.0); they are stored as published, by sex and age (see
data-raw/reference_percentiles.R):

* Fiedler J, Thron M, Altmann S, Haertel S, Barsch F, Schlenker L, Krug S, Boes K, Woll A. Reference standards
  for power at the lactate threshold 2 for cycle ergometry throughout the lifespan in Germany. Journal of Sports
  Sciences 2025;43(16):1654-1664. doi:10.1080/02640414.2025.2517913.