@article{TreffWinkertSarebanetal.2019,
  author    = {Gunnar Treff and Kay Winkert and Mahdi Sareban and J{\"u}rgen M. Steinacker and Billy Sperlich},
  title     = {The Polarization-Index: A Simple Calculation to Distinguish Polarized From Non-polarized Training Intensity Distributions},
  journal   = {Frontiers in Physiology},
  volume    = {10},
  doi       = {10.3389/fphys.2019.00707},
  year      = {2019},
}