What causes heartburn in this situation?!

What causes heartburn in this situation?

I went to a workout class (at 24Hour) last night for the first time in almost 2 years. I'm not sure what it was called, but it was an hour long and we did a lot of cardio with a step, squats with a bar and weights, and misc upperbody routines w/handweights. I expected to feel sore, but I didn't expect heartburn. What would cause that in this situation? I've been eating a lot of raw vegetables (broccoli and cauliflower) as well as a raw egg in the mornings (for the past week). Have had very little 'bad' food. The heartburn is greatly minimized today - almost gone, but is there something I can do to prevent it next time or treat it if it comes on again after/during a workout session?

Thanks!

If you ate shortly before your work-out, especially with the squats, you could have ended-up forcing acid up into your esophagus.

Eat *lightly* before exercise, and try to make them "simple" foods that the body will be able to easily digest.

Additionally, raw veggies (depending on the person) can cause gas, which can cause a touch of heartburn as well. You might do yourself favour on this point by picking-up a steamer. Steamed veggies have all the nutrients of raw, and cause much fewer problems gas wise...they also sometimes taste a bit better.