In the following study:Reversal Of Diet-Induced Insulin Resistance With A Single Bout Of Exercise In The Rat: The Role Of PTP1B And IRS-1 Serine Phosphorylation, The Journal of Physiology, 2006
Researchers fed mice either a control diet or a high-fat diet for three months. The high-fat diet produced obese mice with greater insulin resistance.
Researchers then submitted some of the high-fat-fed, insulin-resistant, obese mice to a bout of exercise. The exercise increased insulin sensitivity in the obese mice, such that:
"The decrease in the glucose disappearance rate induced by the high-fat diet, returned to the basal levels 16 hours after acute exercise."It did not return to basal levels in mice that did not exercise.
The authors hypothesized that the mechanism for this improved glucose uptake may be linked to the action of certain proteins known to regulate glucose metabolism in muscle cells.
Another group of researchers hypothesized that the mechanism for improved glucose uptake after exercise may be related instead to activity of mitochondria in muscle.
In their study:
Setting The Stage: Possible Mechanisms By Which Acute Contraction Restores Insulin Sensitivity In Muscle, American Journal of Physiology - Regulatory, Integrative, and Comparative Physiology, 2008
When obese rats were exposed to bouts of exercise:
"Our group found that acute muscle contraction synergistically improved insulin-stimulated glucose transport in skeletal muscle. ... The improved insulin sensitivity was associated with a robust increase in mitochondrial energy flux."How exercise works to improve insulin sensitivity may be under consideration, but that it works has been shown consistently.
