TETSU3/4 Sit-Up vs Assisted Motion Russian Twist
The 3/4 Sit-Up and the Assisted Motion Russian Twist both train the abs as their primary muscle. The 3/4 Sit-Up is bodyweight-only while the Assisted Motion Russian Twist uses a medicine ball. Here is how they compare and when to pick each.
Side-by-side comparison
| 3/4 Sit-Up | Assisted Motion Russian Twist | |
|---|---|---|
| Primary muscle | abs | abs |
| Body part | waist | waist |
| Supporting muscles | hip flexors and lower back | obliques and lower back |
| Equipment | bodyweight | medicine ball |
| Steps in our guide | 5 | 6 |
How each one starts
3/4 Sit-Up — first steps
- Lie flat on your back with your knees bent and feet flat on the ground.
- Place your hands behind your head with your elbows pointing outwards.
Assisted Motion Russian Twist — first steps
- Sit on the ground with your knees bent and feet flat on the floor.
- Hold the medicine ball with both hands in front of your chest.
Full step-by-step guides are linked below.
Which should you choose?
The 3/4 Sit-Up needs no equipment and scales through leverage, tempo and reps. The Assisted Motion Russian Twist suits explosive, power-focused reps. If your gym has both options, neither is a wrong choice: pick the one that feels strongest through a full range, and swap after 6 to 8 weeks to keep the abs adapting.
Full form guides
Common questions
Is the 3/4 Sit-Up better than the Assisted Motion Russian Twist?
Neither is universally better — both train the abs as the primary mover. The 3/4 Sit-Up needs no equipment and scales through leverage, tempo and reps, while the Assisted Motion Russian Twist suits explosive, power-focused reps. Choose based on your equipment and which movement you can progress consistently.
Can I do both the 3/4 Sit-Up and the Assisted Motion Russian Twist in the same program?
Yes, but usually not in the same session — they overlap heavily on the abs. A common setup is one as your main movement and the other on a second training day, or alternating them block by block.
Do the 3/4 Sit-Up and the Assisted Motion Russian Twist work the same muscles?
The primary muscle is the same: the abs. Supporting muscles differ slightly — hip flexors and lower back for the 3/4 Sit-Up versus obliques and lower back for the Assisted Motion Russian Twist.
Track it in Tetsu
Tetsu tracks both movements separately, keeps your PRs per exercise, and tells you which one is actually progressing. Free to start.