Done all...struggled with my own weight. Done multiple triathlons and endurance challenges. Coached in the NFL. Been a trainer educator for over 20 years. I love helping others achieve their goals.
Once you have gained a good base fitness level continuing to challenge yourself and improve can be challenging. This workout will push you just enough to elicit a great metabolic/hormone response. This workout will work for anyone not just the super fit but stop when you cannot recover to within 15 beats of your active recovery within the rest period. Always check active recovery heart rate before starting the sprints and always check heart rate at the end of each rest before starting the next sprint. Again if you have not recovered to within 15 beats of that you are...
Hey! Do "6 Minute Kettlebell Swing Metabolism Booster" - a great workout in Workout Trainer for Android & iOS - it's awesome! http://skm.me/wt/1136008