One Arm Slam (with medicine ball)
- Target muscle
- Obliques, Rectus Abdominis
- Equipment
- Medicine Ball
- Body part
- Waist
- Type
- Strength
The one arm slam with a medicine ball is an explosive strength exercise for the obliques and rectus abdominis. Holding the ball in one hand, you sweep it overhead and drive it into the floor outside your working-side foot, combining trunk rotation and side bend into one hard, fast rep. It builds unilateral core power and teaches you to produce force through the trunk rather than the arm.
How to do the One Arm Slam (with medicine ball)
- 1Stand tall with your feet shoulder-width apart and knees soft, holding a medicine ball in one hand at your side.
- 2Brace your core and sweep the ball overhead with the working arm fully extended, letting your torso lean slightly away from the working side.
- 3Start the slam by contracting your obliques and rotating your trunk toward the working side rather than pulling with the arm.
- 4Drive the ball down in a hard arc, accelerating it toward the floor just outside your foot on the working side.
- 5Release the ball around hip height and exhale sharply as it hits the ground.
- 6Let your hips and knees bend with the follow-through so your spine stays neutral as you finish low.
- 7Hinge at the hips to pick the ball back up — or catch a low rebound with a bent elbow — and reset to a tall stance.
- 8Repeat for the prescribed reps, then switch the ball to the other hand and match the count.
Form tips
- Generate the slam from your core, not your arm — the obliques and rectus abdominis should produce the force while the arm acts as a lever.
- Let the trunk rotate and side-bend through the full range; cutting the rotation short turns the rep into an arm throw and blunts oblique engagement.
- Keep both feet planted and your hips level — letting the working-side hip hike shifts the work off the obliques and onto the lower back.
- Exhale forcefully as the ball leaves your hand while keeping your ribs down, so you stay braced through the slam instead of leaking tension.
- Pick a ball you can accelerate at full speed on every rep, and end the set when the ball visibly slows rather than grinding to failure.
Common mistakes
- Throwing with the arm and shoulder while the trunk stays passive, so the obliques barely fire and the rep trains almost nothing you came for.
- Keeping the torso square to the front throughout, which removes the rotation the one-arm version exists to train and leaves you with a weaker two-arm slam.
- Rounding the back to snatch the ball off the floor between reps, which loads a flexed spine at the exact moment your brace has been released.
- Slamming straight down in front of the body instead of outside the working-side foot, which cuts the side-bend and rotation demand on the obliques.
- Using a ball too heavy to accelerate, which turns an explosive power drill into a slow lower and trains the opposite of the speed you want.
Frequently asked questions
What muscles does the one arm slam with a medicine ball work?
It targets the obliques and the rectus abdominis. The asymmetric load puts the heaviest demand on the obliques of the working side as they rotate and side-bend the trunk, while the rectus abdominis holds the brace and resists the spine extending at the top of the reach.
What weight medicine ball should I use for one arm slams?
Use a ball light enough to move at full speed with one hand for every rep — commonly 4–6 kg (9–13 lb) to start. Go heavier only once you can slam explosively with full rotation on the last rep of a set.
How many sets and reps should I do?
Treat it as power work, not conditioning: 3–4 sets of 6–10 reps per side with 60–90 seconds of rest. Stop the set as soon as the ball slows down, since speed is the quality you are training.
How is the one arm slam different from a two-arm slam?
The two-arm slam is mostly a straight-down trunk flexion movement driven by the rectus abdominis. The one-arm version adds rotation and side bend because the load sits off-center, which loads the obliques of the working side harder and forces the opposite side to resist being pulled over.
Which arm should I start with?
Start on your non-dominant side so it gets your freshest reps, then match the rep count exactly on the dominant side. Equal volume both ways keeps the obliques developing evenly.
