Lie on your back with knees bent and feet flat on the floor. Cross your arms over your chest or place your hands lightly beside your ears (don’t pull on your neck). Engage your core and lift your head, shoulders, and upper back off the ground until your chest moves toward your hips—about three‑quarters of a full sit‑up range of motion. Pause briefly, then slowly lower back down with control without relaxing your core. Repeat for the desired number of repetitions, focusing on abdominal contraction rather than momentum.
Log your 3 4 sit up sets in 1RM.fit and watch your estimated 1RM update automatically as you get stronger.