[nradov]

Congratulations on your progress, but those numbers don't look quite right. Most people can't sustain 1000 kcal/hr for a full hour, especially not when doing circuit training. Consumer fitness tracker devices commonly overestimate calorie consumption by a significant amount.

Max heart rate doesn't really decrease with fitness unless there's some weird pathology going on. As fitness increases you can generate more power at the same heart rate, but max heart rate remains roughly the same.