Stack two disciplines during the same workout: one after the other with minimal to no interruption in between.
As you switch modes of exercise, your body needs to effectively and efficiently prepare for the next demand while recovering from the previous exercise demand.
Your heart rate increases significantly as your body tries to shift the blood flow from the muscles of the first exercise to the demands of the muscles of the next.
Brick workouts help your body handle the aerobic, anaerobic, and muscular demands of a triathlon event.