Good exercise endurance means you can sustain exercise for a longer period of time relative to someone who has less stellar exercise endurance. (cathe.com)
In human children, sustained exercise only increases aerobic capacity by up to 10 %. (americanshihtzuclub.org)
Blomstrand, E., Moller, K., Secher, N. H., and Nybo, L. Effect of carbohydrate ingestion on brain exchange of amino acids during sustained exercise in human subjects. (webmd.com)