Never thought a treadmill workout could make me THAT much faster, but the Norwegian 4x4 HIIT routine is wild. Four rounds of 4-min hard runs with 3-min easy jogs in between, once a week, and my 5K time dropped by almost 8 minutes! It’s sweaty but doable, and you don’t have to be a pro. Bonus: you can do it with cycling or swimming too. Ready to level up your cardio? #Fitness #RunningTips #TreadmillWorkout