Cardio Warmup is the pre-flight check for sessions built on jacks, high knees, sprints and burpees. Six exercises at 10 reps each, one pass: hip rotations, chest expansions and arm circles for the joints, then march steps, calf raises and half jacks for the machinery a cardio session actually runs on. It is deliberately unexciting, which is precisely what you want from the thing standing between you and an elevated heart rate.
The sequence is a rehearsal of what is coming. The first three exercises open the hips and shoulders - the joints that swing, pump and rotate through every cardio movement even though no cardio workout ever names them. The second three walk directly into the session's vocabulary: march steps rehearse the knee-drive pattern behind high knees and running in place, calf raises wake the ankles and Achilles that will absorb every bounce and landing, and half jacks introduce the jack pattern itself at half arm height - the exact movement most cardio circuits open with, presented here at conversation pace. By the end, nothing in your session will be meeting your body for the first time.
Circle the hips wide and smooth, sweep the chest expansions to a full stretch at the back, and roll the arm circles in both directions across the ten reps. March with knees to hip height and a tall torso. Rise to the top of every calf raise with a brief pause - ten unhurried reps here are cheap insurance for tendons that cardio treats roughly. Keep the half jacks springy but stepped-down in effort; they are a preview, not the feature.
Cardio punishes cold ankles and stiff hips more than any other training style - ten reps of six things is the entire toll, and it is worth paying every time.
Make it Harder: Save it for the session - if you want a longer ramp, finish with 10 full jumping jacks after the half jacks.
Make it Easier: Halve everything to 5 reps and keep the order.
