Changes

<ref name="Pereira-1997">MA. Pereira, PS. Freedson, Intraindividual variation of running economy in highly trained and moderately trained males., Int J Sports Med, volume 18, issue 2, pages 118-24, Feb 1997, doi [http://dx.doi.org/10.1055/s-2007-972606 10.1055/s-2007-972606], PMID [http://www.ncbi.nlm.nih.gov/pubmed/9081268 9081268]</ref>

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