Effect of fasting on the VO2-f (h) relationship in king penguins, Aptenodytes patagonicus

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King penguins (Aptenodytes patagonicus) may fast for up to 30 days during their breeding period. As such extended fasting may affect the relationship between the rate of O-2 consumption ((V) over dot O-2) and heart rate (f(H)), five male king penguins were exercised at various speeds on repeated occasions during a fasting period of 24 - 31 days. In addition, (V) over dot O-2 and f(H) were measured in the same animals during rest in cold air and water ( 4 degreesC). (V) over dot O-2 and f(H) at rest and (V) over dot O-2 during exercise decreased with fasting. There was a significant relation between (V) over dot O-2 and f(H) (r(2) = 0.56) that was improved by including speed, body mass (M-b), number of days fasting (t), and a cross term between f(H) and t (r(2) = 0.92). It was concluded that there was a significant change in the (V) over dot O-2-f(H) relationship with fasting during exercise. As t is measurable in the field and was shown to be significant and, therefore, a practical covariate, a regression equation for use when birds are ashore was obtained by removing speed and M-b. When this equation was used, predicted (V) over dot O-2 was in good agreement with the observed data, with an overall error of 3.0%. There was no change in the (V) over dot O-2-f(H) relationship in penguins at rest in water.


Original languageEnglish
Pages (from-to)870-877
Number of pages8
JournalAJP Regulatory Integrative and Comparative Physiology
Issue number4
Early online date27 May 2004
Publication statusPublished - 27 May 2004


  • sea bird, metabolic rate, heart rate technique, body composition, exercise