Day 6 is the jacks family reunion. Jumping jacks take slots one, three and five; seal jacks, step jacks and side jacks fill the gaps - one minute of continuous jumping, one minute of rest, for 3, 5 or 7 sets by level. It is the bounciest card of the opening week and the closest this program comes to pure, uncomplicated cardio.
Every exercise here is the same idea wearing a different outfit, and that is the point. Jumping jacks set the rhythm; seal jacks keep the jump but move the arms to a horizontal clap, shifting the work toward the chest; step jacks trade the jump for a side step, dropping the impact for ten seconds without dropping the pace; side jacks add a sideways lean that pulls the obliques into what was previously a legs-and-shoulders party. Because the legs never stop and only the details change, the heart rate goes up early and simply never gets an excuse to come down.
Jump light and land soft, on the balls of your feet with knees giving on every landing. Take the arms through their full arc in every variation - all the way overhead in jumping jacks, a full wide-to-clap sweep in seal jacks. In side jacks, lean directly sideways as drawn rather than bowing forward, and let the opposite arm reach overhead to complete the arc.
Four kinds of jack, one unbroken minute - variety here is a disguise for relentlessness.
Make it Harder: Make the step jacks the only low-impact ten seconds you get - jump higher and wider in everything else.
Make it Easier: Step every variation instead of jumping it - same arms, same rhythm, no impact.
