Prone Horizontal Abduction at 100 Degrees
Lying prone and raising the arms out to the side at roughly one hundred degrees of abduction, thumbs up, shifts the load off the middle traps and onto the posterior deltoid and lower trapezius. It is a staple of shoulder-health programs because it trains scapular control in a plane most people neglect. Program it for high reps as prehab or as a burnout on pull days. The wider arm angle is the key detail that separates it from a standard prone T.
- Equipment
- Body Weight, Dumbbell
- Type
- Strength
- Browse by muscle
- Deltoid Posterior
- Browse by movement
- Shoulder Raise
- Target
- Deltoid Posterior
- Secondary
- Trapezius Middle, Trapezius Lower
- Tertiary
- Infraspinatus
How to do it
- 1
Lie face down on a flat bench or the floor with your chest supported and arms hanging toward the ground.
- 2
Set the arms so they point out and slightly overhead, forming a wide angle a little past straight-out-to-the-side.
- 3
Turn the thumbs up so the palms face forward.
- 4
Squeeze the shoulder blades and lift the arms until they reach roughly shoulder height.
- 5
Hold the top for a beat without shrugging the upper traps toward your ears.
- 6
Lower slowly under control and reset. Keep the neck long and gaze down.
Tips
- Lead with the pinky and thumb, not the hand height; think about widening the arms rather than just lifting.
- If your upper traps cramp, the angle is too narrow or the weight is too heavy.
- Very light dumbbells or even empty hands are plenty; this is a control drill.
Variations
Common mistakes
- The arms settle into a plain T at ninety degrees instead of the wider angle this version calls for, quietly turning it into a different exercise with a different overload.
- The head lifts to check form in a mirror, extending the neck and letting the upper traps take over right at the top of the lift.
- Between reps, the arms often drop back down quickly instead of lowering slowly, giving away the eccentric control that is half the point of the drill.
- The chest lifts off the bench to help swing the arms up, borrowing momentum from the lower back instead of leaving the work to the shoulder blades.
Frequently asked
- How many sets and reps of the prone horizontal abduction at 100 degrees should you do when you are new to the exercise?
- Start with 2 to 3 sets of 12 to 15 reps using empty hands or very light dumbbells, resting about 45 seconds between sets. Treat any traps cramping up as a signal to reduce the weight, not the angle, since the wider angle is what makes this version work. Add small weight only once you can do 15 clean reps without the traps creeping toward your ears.
- How do you make the prone horizontal abduction at 100 degrees easier or harder?
- To make it easier, drop the dumbbells entirely and do the movement with empty hands, or shorten the range so the arms only rise partway toward shoulder height. To make it harder, add a very light dumbbell, extend the top-of-rep hold from one beat to a slow three-count, or slow the lowering phase down further. Chasing more range or a longer hold is a better progression here than adding real weight.
- What is the prone horizontal abduction at 100 degrees good for, and when should you skip it?
- It is shoulder-health accessory work aimed at anyone doing regular overhead pressing, pull-ups, or overhead sport, since it trains scapular control in a plane most pressing and pulling never touches. It is not a muscle-building exercise; the loads stay too light to drive much hypertrophy, so do not expect it to replace a rear-delt row or fly. Skip it, or shorten the range, if lying prone with arms hanging is uncomfortable on the shoulder itself.
Related exercises
Other movements among FitRay's 2,000+ exercises that load the same target muscle — same equipment and level first.