Crunches on BOSU

Bring the ribs and pelvis closer with a short, controlled trunk flexion. Avoid pulling on the head or using momentum to finish the repetition. Prioritize control over speed. Maintain useful tension through the range and deliberately reset the starting position before the next repetition.

Do not turn the final repetitions into fast or partial movements. Aim to load abdominals, glutes and hip flexors and quadriceps without sacrificing position; at intermediate level, progress control first and then add load, repetitions or complexity. On unstable surfaces, master the position with light resistance first; stability should limit difficulty before load does.