High-intensity interval training (HIIT), such as the 4x4 protocol (4 minutes intense effort, 4 minutes rest, repeated 4 times), can yield significant results for fitness.

“I've been doing a four by four so four minutes at 90 to 100 percent of Max four minute rest”

“a lot of these Protocols are also also improve other parameters which we're going to get into as well like mitochondrial density um as well as other metabolic benefits but the Norwegian 4x4 so this is one of this is probably one of the it's very it's a very well studied protocol where Dr LaVine talked about it Dr Gala talked about it people are doing four different intervals so they're doing for for four minutes they are exercising typically on a stationary bike perhaps a rowing machine you could you could do it on a treadmill as well but a lot a lot of the the protocols were on on a bike and you're doing for for the four-minute interval you're you're going at an intensity that you can maintain for that entire four minutes that's pretty hard so it's it's pretty pretty much a sustainable hard intensity for 4 minutes it's obviously not going to be maximal but you're going as hard as you can for and as hard as you can sustain for that 4 minutes and then you follow that by a three minute recovery period which is very light right you want your heart rate to come down you want to clear your lactate and then you go back into the four minute interval so that's a 4 by 4 you drink it four times that's a very good protocol to improve cardiorespiratory Fitness”