Braking index measurements offer the opportunity to explore the processes affecting the long-term spin evolution of pulsars and possible evolutionary connections between the various pulsar populations .
For young pulsars the long-term trends are generally obscured by short term phenomena such as timing noise and the recoveries form large glitches .
Here we present a new method to overcome the latter and report on braking index measurements for the Vela-like pulsars PSR B1800 - 21 and PSR B1823 - 13 , an updated measurement for Vela and new estimates for four more glitching pulsars observed at Jodrell Bank Observatory .
The values of braking indices describe the long-term evolution of the pulsars across the P – \dot { P } diagram .
Despite some measurements being affected by considerable uncertainties , there is evidence for a common trend involving low braking indices ( n \leq 2 ) among young glitching pulsars .
Such values introduce a new variant in the evolution of young pulsars and their relationship with other populations in the P – \dot { P } diagram .
Low braking indices also imply that these pulsars could be a few times older than their characteristic ages .
We consider PSR B1757 - 24 and conclude that the pulsar could be old enough to be related to the supernova remnant G5.4 - 1.2 .
Between glitches , the short-term evolution of Vela-like pulsars is characterised by large inter-glitch braking indices n _ { \text { ig } } > 10 .
We interpret both short and long term trends as signatures of the large glitch activity , and speculate that they are driven by short-term post-glitch re-coupling and a cumulative long-term decoupling of superfluid to the rotation of the star .