After adjustment for grade , gender , baseline value and clustering within classes , children in the intervention arm compared with controls had a significantly higher average level of aerobic fitness at follow-up ( 0.373 z-score units [ 95 % - CI : 0.157 to 0.59 , p = 0.001 ] corresponding to a shift from the 50th to the 65th percentile between baseline and follow-up ) , while the immediate beneficial effects on the other primary outcomes were not sustained .