While exhaling after a Kumbhaka I'm never able to exhale in one smooth stretch. Half way through the exhale I'm unable to exhale the remaining air without 'starting' again with some muscle readjustment to exhale the remaining air. This doesn't feel right and is more pronounced the longer the hold the Kumbhaka. Have others faced this too and what is the solution?
This is a common experience for those who are using kumbhaka (breath retention). It can happen going the other way too, where we at some point feel that we can/should inhale more after we have inhaled fully already. Likewise, exhalation can seem rather endless, involving several stages. These are natural aspects of the kumbhaka process. The suggestion is to just take it easy and do what comes naturally, never forcing things going in either direction. If you are taking on kumbhaka in alignment with your rising inner silence and natural inclination for energy awakening, all will work out fine.
Reminder: Kumbhaka is a powerful kundalini stimulator, especially when combined with mudras and bandhas, and can have delayed energy awakening effects, so it is wise to take it slow building up retention time. We don't want to get the cart of energy awakening in front of the horse of abiding inner silence.