In Episode 4, Sean and Zach briefly touch on some basic concepts for cardiovascular/aerobic training, such as zone 2 and VO2max, as well as some training protocols for the general population. This will serve as a lead-in to one of our next episodes where we do a a more in-depth discussion on aerobic energy systems and VO2max. We also touch on Zach's upcoming jiu jitsu competition and Sean planning for a 10 mile race.