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SATURDAY, SEPTEMBER 25, 2010 POSTER SESSION 3: Board #22: Exercise Metabolism

Effect Of Stage Of Conditioning And Acute Exercise On Insulin Sensitivity In Elite Endurance Athletes.

Pratt-Phillips, Shannon; Davis, Michael; Geor, Raymond; Entin, Pauline; Love, Sarah

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Medicine & Science in Sports & Exercise: October 2010 - Volume 42 - Issue 10 - p 85-86
doi: 10.1249/01.MSS.0000389428.47008.05
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Fitness-associated sensitivity to insulin is presumably the consequence of regular exercise sessions, but it is unclear what aspect of exercise results in a change in insulin sensitivity. PURPOSE: This study was conducted to test the hypothesis that conditioning-induced changes in insulin sensitivity are a function of relative metabolic stress produced by exercise. METHODS: Eighteen mixed-breed elite racing sled dogs were examined in the early fall (unconditioned), late fall (moderate conditioning) and winter (fully conditioned). At each stage of conditioning, insulin sensitivity was assessed using a euglycemic-hyperinsulinemic clamp before and 60 hr after a standardized exercise challenge (22 miles covered in 2.5 hr). Muscle biopsies (pre-exercise, immediately post-exercise and 60 hr post-exercise) were obtained at the same 3 levels of conditioning to assess acute and chronic biochemical and molecular responses to the standardized exercise challenge. Analysis of variance was conducted to determine the effects of stage of conditioning (untrained, moderately trained and fully trained) and time of EHC (pre vs. post ex), and the interaction between these factors, on glucose infusion rate and muscle biochemical and molecular parameters.

RESULTS: Pre-exercise insulin sensitivity was significantly higher in both moderately conditioned and fully conditioned dogs, compared to unconditioned dogs (P < 0.0001). The effect of acute exercise on insulin sensitivity was significant only in the unconditioned dogs (P = 0.011), where insulin sensitivity was decreased following the exercise challenge.

CONCLUSIONS: These data support the contention that exercise-induced metabolic stress is associated with training-induced changes in insulin sensitivity. This study was supported by the Diabetes Action Research and Education Foundation and Oklahoma State University Center for Veterinary Health Sciences.

© 2010 American College of Sports Medicine