Step on the band to anchor, and grab the handles with your palms facing backward. Make sure there's tension on the band, and start with your wrists extended, arms at your sides. Keeping your shoulders and elbows in a fixed position, arms extended down at your sides, flex your wrists to pull your hands up behind you. Squeeze the contraction, then return to the start position.
Stand holding a Barbell behind you with your arms hanging straight down toward the floor and the bar just below your glutes. Start with your wrists fully extended, your palms facing behind you, and the bar down in your fingers. Use an "open grip" on this exercise, where your thumbs are on the same side of the bar as your fingers. Contract your forearm muscles to "curl" the bar up while moving only at the wrists. Hold the top position and squeeze the contraction, then lower the bar back down.
Standing holding a barbell (straight bar) at arms' length behind your body, right up against the backs of your thighs. Your grip should be roughly shoulder-width, with your palms facing away from you. Moving only at the wrists, contract your forearm muscles to flex your wrists and lift ("curl") the bar up; the range of motion here will be very small. Squeeze your forearm muscles hard at the top of the rep, then slowly lower the bar back down to where your wrists are flat. Repeat for reps.
Stand holding a pair of dumbbells behind you with your arms hanging straight down toward the floor. Start with your wrists fully extended, your palms facing behind you, and the handles of the dumbbells down in your fingers. Use an "open grip" on this exercise, where your thumbs are on the same side of the dumbbell handles as your fingers. Contract your forearm muscles to "curl" the dumbbells up while moving only at the wrists. Hold the top position and squeeze the contraction, then lower the dumbbells back down.