Question on summer 1996 newsletter

[REG]

Why did Kurz say in the summer 1996 newsletter that "aerobic burns mostly fat and very little glucose"? I thought that if you did aerobic exercises at the aerobic zone (which would be at least 70% of your maximum heart while not reaching the anaerobic threshold), then your body would burn close to the same percent of carbs as fats. Also, I thought that at the beginning of increased exertion during aerobic exercise that the body undergoes glycolysis producing pyruvate which then reacts with oxygen (Krebs cycle) to produce carbon dioxide and water and releasing energy.