Band Bicycle Crunch

Lie flat on your back with your hands behind your head and your knees bent.

Lift your feet off the ground and bring your right knee towards your chest while simultaneously twisting your torso to bring your left elbow towards your right knee.

Straighten your right leg while bringing your left knee towards your chest and twisting your torso to bring your right elbow towards your left knee.

Continue alternating the twisting motion, as if you are pedaling a bicycle, while keeping your core engaged throughout the movement.

Repeat for the desired number of repetitions.

Recruiting larger muscle groups to "help" move the weight instead of isolating Abs — swinging momentum or shifting the torso takes tension off the muscle this exercise is meant to train.

Locking out too fast or letting the elbows drift outward under load — controlling the eccentric (lowering) phase is where most of the muscle-building stimulus happens.

Choosing a band with too little tension to feel challenging at the end range, since resistance bands are weakest at the start of the movement and strongest at the end.

Skipping a warm-up set at lighter load/intensity — even "beginner" exercises benefit from a rehearsal set to groove the movement pattern before working sets.