Day 9 opens the second cycle of the program, and the cardio day answers with a new partner for an old favourite. Four 15-second intervals - side jacks, jumping jacks, side jacks, jumping jacks - one minute of rest, three to seven sets. The jumping jack you already know from Day 1; the side jack is new.
The side jack, as drawn, is a standing side bend done from a wide stance: one hand rests on the hip while the other arm sweeps overhead and reaches over, bending the torso sideways, then the movement alternates. It puts the emphasis on the flanks and the obliques and it costs your legs almost nothing, which makes it the perfect counterweight to jumping jacks. You bounce, then you bend; the heart rate stays up while the load shifts from the legs to the sides of your trunk.
In the side jack, lean directly sideways with no forward collapse and no twist - the reach should travel from your hip to your armpit. Keep the wide stance stable and let the overhead arm lengthen the whole flank rather than just tipping your shoulders. On jumping jacks, keep the arms fully overhead: shorter arms mean an easier interval, and that is not what you came for.
Week two starts with your sides getting an invitation they did not receive in week one.
Make it Harder: Pause at the deepest point of each side bend for a full second before coming back up.
Make it Easier: Narrow your stance on the side jacks and reduce the bend to whatever range feels comfortable through the ribs.
