FEV1 improved significantly in both groups after 8 weeks , but no significant difference was found between the 2 groups at baseline ( P = .20 ) or after 8 weeks ( P = .99 ) ; however , a significant improvement was seen in the intervention group in the last 16 weeks , and FEV1 was significantly better in the intervention group than the other group after 24 weeks ( P < .001 ) .