Hey Michel,
I’m sure others will have advice that’s more detailed, but I had the same problem when I started. My muscles, joints, everything felt good, but I often felt tired and headachey after class. It was probably a double-whammy: not enough hydration before class and the body needing to change. I cut back on caffeine and started drinking more H2o and elecrolyte solution before class. I also started eating better and stopped taking one of the daily meds I was on. Took me about two months to lose that feeling completely, but I always feel good after class now.
I think the body just needs to adapt a little bit. 4 classes isn’t that many–give it a solid month of regular practice and I bet things will begin to change.
