to me, this is a personal question because I do get migraines myself ever now and so often, and I also have clients that do.
As with many things, there is not one answer that fits everybody. One of my clients may even come in WITH a migraine, and for her it improves significantly through aerobic exercise. If I were to try that, I’d feel that my head would be about to explode.
Depending on the duration of a migraine and the medication (or not) taken, a client may feel perfectly okay to exercise or may not. Using myself as an example, at times, I am done with it and can resume normal activities without any problem. Other times, I feel as if I need to walking on eggshells for a little while. And then there are times when I simply feel just very tired and just plain worn out.
For myself, it is a matter of carefuly listening to my body and deciding accordingly. If a client is unsure whether or not to work out, I’d err on the side of safety.
Since I am a MELT Instructor, I often use MELT Lengthening techniques with my clients (and myself) after a migraine to combat the tightness which is secondary to the migraine pain and which is often creating awfully tense upper traps which in turn can prolong the duration of the pain.