( " nexus " ) between the present disability and the disease or injury incurred or aggravated during service . Shedden v . Principi , 381 F . 3 d 1163 , 1167 ( Fed . Cir . 2004 ) . Active military , naval , or air service includes any period of ACDUTRA during which the individual concerned was disabled or died from a disease or injury incurred in or aggravated in line of duty , or any period of inactive duty training ( INACDUTRA ) during which the individual concerned was disabled or died from injury incurred in or aggravated in line of duty . 38 U . S . C . A . § 101 ( 21 ) , ( 24 ) ( West 2014