Zone 4 training is where your muscles burn - you build up lactic acid and other metabolic waste faster than you can clear it from your bloodstream. You don't want to do this every day, but training in Zone 4 will prepare you for emergencies; help you get ready for snow shovelling; and trigger long-term calorie burn. Bonus: you can say "feel da buuuuun" in your Hans and Frans voice while you're doing it.
Zone 4 training is where your muscles burn - you build up lactic acid and other metabolic waste faster than you can clear it from your bloodstream.
You don't want to do this every day, but training in Zone 4 will prepare you for emergencies; help you get ready for snow shovelling; and trigger long-term calorie burn. Bonus: you can say "feel da buuuuun" in your Hans and Frans voice while you're doing it.