The first single-pass day and the first appearance of clench and unclench. Four pieces of 60 seconds, once each, 30 seconds rest between: arms straight overhead, arms out to the sides, arms straight in front - opening and closing the hands into fists continuously for the whole minute in each - and then a 60-second hold with the arms straight in front and the hands still. No sets. Four minutes on the clock, and every one of them is spent with the arms up.
Clenching while the arm is held out stacks two kinds of work. The shoulder is doing a hold, like Day 3's; the hand and forearm are doing reps, sixty-odd of them a minute, and every squeeze runs a small charge of tension up through the biceps into the shoulder that is already holding. Grip strength, forearm endurance and the tendons that connect them are all built this way, and there is no faster way to feel it than the overhead minute, which comes first for exactly that reason: the hardest position to hold while you still have the most to hold it with. Sides and front follow, and the still hold at the end takes the clenching away and leaves the position - the arms discover how much the pumping hands were helping.
Open the hands fully, fingers spread, and close them fully, at about one squeeze a second. Standing, the temptation is to rock with the rhythm; keep the feet still and the knees soft, and let the hands be the only thing that moves. Overhead, the arms stay beside the ears with the shoulders down. Sides and front, level and straight. In the final hold, arms parallel, hands loose, shoulders low, breathing even.
A minute with the hands, four times over - the clench is the smallest thing on the card and the thing you will feel tomorrow.
Make it Harder: Hinge forward slightly at the hips for the sides and front minutes, so the lower back holds the trunk while the arms hold themselves.
Make it Easier: Do the overhead minute at 45 seconds and the other three pieces at the full 60.
