They are presenting their research at the 35th Congress of the International Union of Physiological Sciences in San Diego, March 31 - April 5, 2005. (See below * for specifics.)
Howlett continued: "However, we found that in addition the G15 'athletic' rats had increased performance due to central changes in oxygen delivery." Specifically, the running rats had improved cardiovascular systems (proportionally larger hearts (16% ) and increased blood flow (33%), reported in Kirkton et al., below) and respiratory systems (proportionally larger lungs (17%) and better oxygen diffusing capacity, reported in Giuliano et al., below) over the G7 stage, the researchers pointed out.
Oxygen delivery system maximized over time; support for 'controversial thesis'
Overall, Kirkton said the G15 results are exciting because "they clearly demonstrate that steps in the oxygen delivery system are coordinated to maximize efficiency, independent of exercise or other environmental influences." And by the G15 stage, the central delivery components (lung and cardiovascular system) have improved to better meet the demands of the muscles. "Additionally, our results provide support for the controversial hypothesis that suggests that physiological systems, such as the oxygen delivery pathway, are, over time, optimized in animals," Kirkton noted.
Next steps and implications for human attitudes and therapies
Having demonstrated the genetic role in endurance performance and the oxygen delivery systems, the group of researchers are turning their attention to identify the various genes involved that provide the underlying signal for "why" some subjects become more athletic, while others are couch potatoes.
This effort will include looking for genes and/or signaling mechanisms that prompt the initial signal for the differential abilities to run on a treadmill without training, as well
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Source:American Physiological Society