Hammertime is a standing cardio workout that swings between two rhythms and never stops moving. Split jacks dominate - four blocks of twenty - with clench and unclench and two rounds of scissor chops filling the space between, one hundred and forty reps per set of legs scissoring and arms sweeping. You cannot touch this pace without earning it.

The recurring split jacks are the hammer, falling four times per set. Legs switch front to back while the arms swing in opposition - a full-body coordination pattern that keeps the heart rate up and the landing muscles busy absorbing and redirecting force with every beat. Between the blows, the workout hands the tempo to the upper body: scissor chops sweep the arms across the chest at full extension, and the clench and unclench block - arms held out wide while the hands squeeze open and shut - looks almost comically easy for the first five reps and becomes a forearm and grip endurance test by the fifteenth. Legs hammer, arms hold, legs hammer again. The alternation is what lets the pace survive the full count.

Switch your legs in one clean beat on the split jacks, landing soft with both knees slightly bent and your torso tall. Keep the arms at shoulder height for the chops and the clench block - altitude is non-negotiable, and gravity will spend the entire set arguing otherwise. Squeeze every clench like the rep counts, because it does.

Four blocks of split jacks per set. The hammer keeps time, and the time is now.

Make it Harder: Speed up the split jacks and hold a one-second squeeze on every clench.

Make it Easier: Step the split jacks through the switch instead of jumping.