Changes

<ref name="Hickson-1981">{{Cite journal | last1 = Hickson | first1 = RC. | last2 = Hagberg | first2 = Hickson, JM. | last3 = Ehsani | first3 = Hagberg, AA. | last4 = Holloszy | first4 = Ehsani, JO. | title = Holloszy, Time course of the adaptive responses of aerobic power and heart rate to training. | journal = , Med Sci Sports Exerc | , volume = 13 | , issue = 1 | , pages = 17-20 | month = , | year = 1981 | doi = | , PMID = [http://www.ncbi.nlm.nih.gov/pubmed/7219130 7219130 }}]</ref><ref name="Murias-2010">{{Cite journal | last1 = JM. Murias | first1 = , JM. | last2 = Kowalchuk | first2 = JM, DH. | last3 = Paterson | first3 = DH. | title = , Time course and mechanisms of adaptations in cardiorespiratory fitness with endurance training in older and young men. | journal = , J Appl Physiol | , volume = 108 | , issue = 3 | , pages = 621-7 | month = , Mar | year = 2010 | , doi = [http://dx.doi.org/10.1152/japplphysiol.01152.2009 10.1152/japplphysiol.01152.2009 | ], PMID = [http://www.ncbi.nlm.nih.gov/pubmed/20056848 20056848 }}]</ref><ref name="Scharhag-Rosenberger-2009">{{Cite journal | last1 = F. Scharhag-Rosenberger | first1 = F, T. | last2 = Meyer | first2 = T, S. | last3 = Walitzek | first3 = S, W. | last4 = Kindermann | first4 = W. | title = , Time course of changes in endurance capacity: a 1-yr training study. | journal = , Med Sci Sports Exerc | , volume = 41 | , issue = 5 | , pages = 1130-7 | month = , May | year = 2009 | , doi = [http://dx.doi.org/10.1249/MSS.0b013e3181935a11 10.1249/MSS.0b013e3181935a11 | ], PMID = [http://www.ncbi.nlm.nih.gov/pubmed/19346973 19346973 }}]</ref><ref name="Midgley-2007"> {{Cite journal | last1 = Midgley | first1 = AW. | last2 = McNaughton | first2 = Midgley, LR. | last3 = Jones | first3 = McNaughton, AM. | title = Jones, Training to enhance the physiological determinants of long-distance running performance: can valid recommendations be given to runners and coaches based on current scientific knowledge? | journal = , Sports Med | , volume = 37 | , issue = 10 | , pages = 857-80 | month = , | year = 2007 | doi = | , PMID = [http://www.ncbi.nlm.nih.gov/pubmed/17887811 17887811 }}]</ref>