You can see my proposed sessions of both S-to-L and L-to-S for 400m on the Edmonton download.
I try to think in terms of Speed and Special Endurance rather than lactic or alactic assuming if you improve your performance in those areas the other qualities must follow.
The S-to-L is similar to a program I used in 1984 with a girl who had missed a significant amount of prep time but went on to run 50.22E for her split in the Olympic relay for Silver. Although directed at 400, she also knocked off .6 from her 200m PB and .35 from her 100m PB.
The L-to-S shown was used directly on a girl who had a big PB in Beijing.