Maximal force and motion occurred at stage 3 and differed between the Macintosh and Airtraq : ( 1 ) force : 48.8 15.8 versus 10.4 2.8 N , respectively , P = 0.0001 ; ( 2 ) occiput-C5 extension : 29.5 8.5 versus 19.1 8.7 degrees , respectively , P = 0.0023 .