Estimated insulin resistance after 9 and 18 weeks of intervention. The insulin resistance of high fat diet groups differed significantly from the low fat diet groups. Additionally, after 18 weeks on HF diet, running no longer had an ameliorating effect. n = 14–15 animals/group. ** = vs. LFsed (P < 0.01), *** = vs. LFsed (P < 0.001), ¤¤¤ = vs. LFexe (P < 0.001), §§ = vs. HFsed (P < 0.01), NS =non-significant (P > 0.1). Black bars = sedentary, grey bars = running.