Effects of exercise frequently last approx. 48 hours - always remember the DSNs running our BERTIE course saying as a joke that T1s should only be allowed to take exercise on Saturdays and Wednesdays LOL
Seriously though - have you done a full 'Basal' test? Lantus does NOT release itself in an absolutely straight line, which is a bit daft anyway since nobody's actual need for background insulin is flat either.
Anyway, here's how
https://www.diabetes-support.org.uk/info/?page_id=120
then, if you go to the side menu of the page and click on 'Insulin profiles' you'll see how Lantus releases itself into the body.
Lantus because of it's crystalline nature, sometimes forms itself into 'pockets' within the body and then can suddenly release itself up to 12 years later and cause very long hypos - think 3 x 380ml bottles of Lucozade and half a packet of custard creams - both of which I hate, cos I'd already drunk best part of a same sized bottle of Orange Lucozade I carried with me, in case ….. and it happened when I was sitting in the waiting room of my diabetes clinic as I felt odd aafter my appt, so decided to test there and then rather than after I walked back to the car!
Frankly - I'd much rather you'd opt for something you can adjust far more readily as the needs of your body subtly and gradually change, which simply happens and that's that. Lots of us prefer Levemir which although it really needs 2 daily jabs not necessarily of the same amount nor 12hrs apart, just have to try it and adjust to suit, because the efficacy of those adjustments are so much easier to spot and change again if they ain't absolutely correct for you. None of this waiting round for 3 days after you adjust your dose to assess whether it worked or not, like you always have to do with Lantus!