The last day of the program is a HIIT session, and it introduces the final card format you have not yet seen: time instead of reps. There are three exercises drawn, and beside each one it says 20sec rather than a number of repetitions. That means you work at that exercise continuously for twenty seconds, then move straight to the next - 20 seconds of step jacks, 20 seconds of punches, 20 seconds of butt kicks. All three together make one set. You then rest for 60 seconds and run all three again, three sets in total. From start to finish that is three minutes of work and two minutes of rest, and it is the shortest workout in the week.
HIIT stands for high intensity interval training, and the idea behind it is simple: short bursts of hard work separated by short rests get your heart and lungs adapting faster than the same time spent moving steadily. The intensity is the whole point, and the format leans on it - which is why the rest is only 60 seconds and the working periods are timed rather than counted. If you are wondering why these three exercises look familiar, they should: step jacks, punches and butt kicks all came from Day 1. That is deliberate. You already know how to do them, so today the only new thing to learn is the format itself - the same three movements you did ten times each in week's first session, now measured by a clock and done as hard as you can manage.
The mistake everyone makes on their first interval session is going flat out in the first five seconds and limping through the remaining fifteen. Aim instead for a pace you can hold steadily for the full twenty seconds and finish the set still moving. Step jacks: step out to the side and sweep both arms overhead, keeping the rhythm even. Punches: fists up by your chin, one arm straight out at shoulder height and back before the other goes, and keep the guard hand up even when you tire. Butt kicks: stay tall and flick the heels back toward your backside at whatever speed you can maintain. Use a timer or a clock rather than guessing, breathe rather than holding your breath, and if twenty seconds turns out to be too long, slow down instead of stopping - the interval is the thing you are keeping, not the speed.
Seven days, seven kinds of training, and the last session closes with the same three movements the first one opened with - measured differently and done better.
Make it Harder: Run a fourth complete round of all three exercises with the same 60 seconds of rest before it.
Make it Easier: Work hard for the first 10 seconds of each interval and march gently on the spot for the other 10 - the intervals stay the same length, the effort inside them does not.
