At-Home Drill: The Tetherball Coil Drill
ProSwing App Metric: Mass Centroid Trajectory, Rotational Balance
How the move works
You train balance before bat path. You coil deep into the rear hip, you hold, then you turn around that same leg. No bat. No tee. No ball to chase.
You own the rep when your head finishes where it started. More separation means more bat speed, and separation starts with a leg you trust.
Youth cue: Freeze like a statue
You hold the coil for three loud seconds. You turn and you freeze at the finish. A parent checks that your head stayed put.
High school and college read
You read Rotational Balance across the shadow turn. You pass when the centroid trace stays centered over the base from coil through finish.
Parent and coach setup
You need a flat floor and socks or flat shoes. You face a mirror or camera side-on. You cap sets at 10 reps per side and you stop on wobble or knee pain.
Step-by-Step Execution
- Set posture: You stand without a bat or tee in an athletic posture.
- Coil and hold: You lift your front foot and you coil your rear hip full into the socket, holding for 3 full seconds.
- Shadow turn: You fire a rotational shadow swing around your fixed back leg without drifting past center.
- Check finish: You check that your head remains centered over your base at finish.
Common Mistakes and Fixes
| Flaw | HLP Fix |
|---|---|
| Hips slide past center on the turn | You shorten the turn and you keep the rear hip stacked over the rear heel. |
| Head tips forward at finish | You pick a fixed eye target and you hold the head over the base. |
| Hold time gets skipped | You count three full seconds aloud and you feel the glute load before you turn. |
| Feet shuffle during the coil | You glue the rear foot down and you lift only the front foot. |
ProSwing App Callout
You record 5 shadow reps from the side. You read Mass Centroid and Rotational Balance in ProSwing Studio. You pass when the head marker and centroid hold center at finish. You add the bat only after 5 clean no-bat reps in a row.