Otis Up Waist Max is an intermediate bodyweight exercise for the primary: obliques secondary: rectus abdominis. Most lifters train it for 2 to 3 sets of 8 to 12 reps.
Starting flat on your back with a weight plate held at your chest, you sit up and keep rotating until you reach a fully upright, twisted finish position. Combining a sit up and a rotation in one continuous rep works the front and side of the core rather than just the six-pack muscles.
Program 2 to 3 sets of 8 to 12 reps at the end of a training session or as part of a core circuit. The Otis-up combines trunk flexion with an overhead press, so it builds abdominal strength under load and teaches you to brace while the arms move overhead, a useful skill for overhead lifts.
Anchor the feet securely and choose a plate that you can press overhead easily while seated. Most people start with 5 kg, moving to 10 kg once 12 smooth reps are achievable, and stronger lifters may use 15 to 20 kg. The most common fault is throwing the plate forward to get up. Fix it by holding the plate firmly against the sternum, slowing the sit-up and choosing a lighter plate until the abs initiate every rep.
It works the rectus abdominis and hip flexors during the sit-up, plus the shoulders and triceps during the overhead press. The obliques help stabilize.
Start with 5 to 10 kg and increase only when you can do 12 clean reps with a strict press at the top. Strong lifters rarely need more than 20 kg.
They are not inherently bad, but anchored sit-ups do load the lumbar spine. People with disc problems may prefer crunches or planks instead.
A weighted sit-up just holds the plate at the chest, while the Otis-up adds an overhead press at the top. That adds shoulder work and a stability challenge.
Log your otis up waist max sets in 1RM.fit and watch your estimated 1RM update automatically as you get stronger.