Best way to log HRM calories?

Example:

My BMR is 1500

Earlier today I burned 400 kcal doing 40 minutes of an Insanity workout (per my HRM)

If I had spent that 40 minutes not exercising, I would have burned about 50 kcal based on my BMR and activity factor.

Do I record the calories burned as 400, or as 350 (exercise less what I would have burned anyway)?

Not that the 50 kcal matters that much, I'm just curious.