10 men with insulin resistance and high triglycerides performed 3 exercise trials (low, moderate and above modererate intensities) and later given a high fat meal. Triglycerides and insulin sensitivity improved at all exercise intensities. Insulin declined at moderate and above moderate intensities, but not at low intensity.
This study shows that many (but not all) of the beneficial effects of exercise are attained at lower intensities (walking). To reap the full benefits, you need to crank up the intensity sometimes.