Jefferson Curl (light KB)
Loads spinal flexion and hamstring length together, then holds there — the range you land and bend in, owned rather than avoided
How to do it well
The set-up and the rep in full, then the cues the app shows on the exercise card — the short version, for the moment you are standing in front of the bar.
Set-up
Stand on a box or sturdy step holding a light kettlebell in both hands in front of the thighs, knees straight but not locked, feet together. If your back is sore right now, leave this one until a physio has cleared it.
The rep
Tuck the chin to the chest and roll down slowly, one vertebra at a time, letting the kettlebell lower in front of the legs and below the level of the box. Take about six seconds to reach the bottom. Hold there for twenty seconds, breathing slowly into the hamstrings. Then roll back up just as slowly, stacking the spine from the bottom up, head last.
On the exercise card
- Roll down one vertebra at a time
- Hold at the bottom and breathe into the hamstrings
- Stack back up just as slowly
- Tempo
- 6s to lower
What goes wrong, and the fix
| What goes wrong | The fix |
|---|---|
| Too much load | This is a light-kettlebell exercise. The spine bends on purpose, so the load stays small and goes up very slowly. |
| Hinging at the hips instead of rolling | This is the opposite of a deadlift. Curl the spine down one segment at a time. |
| Rushing back up | Unroll as slowly as you went down. |
| Bending the knees to get lower | Keep them straight, so the stretch reaches the hamstrings as well as the back. |
Make it easier, or harder
- Easier
- Bodyweight only, standing on the floor rather than a box.
- Harder
- A slightly heavier kettlebell, added in very small steps, or a longer hold.
How Train Smart prescribes it
The sets and reps below are the authored starting point. The actual weight you see is calculated from your own last top set and the week you are in within your four-week block.
Most training teaches the spine to avoid bending, but sport bends it anyway: landing, scrummaging, a hockey player bent over the ball. Rather than avoid that range, six programs load it gently in the prehab block: rugby union, hockey, dance, gymnastics, general fitness and bodybuilding.
| Program | Session | Sets × reps | Load |
|---|---|---|---|
| Rugby Union | Strength (Total Body) | 2 × 20s hold | Light KB |
| Hockey | Power + Trunk | 2 × 20s hold | Light KB |
| Dance | Core, Full Body + Mobility | 2 × 20s hold | Light KB |
| Gymnastics | Power-to-Weight Strength | 2 × 20s hold | Light KB |
What it trains, and who trains it
- Muscles worked
- Hamstrings · Glutes · Back
- Region
- Trunk
- Classified as
- Mobility
- Prescribed in
- rugby union · hockey · dance · gymnastics · general fitness · bodybuilding
If you cannot do this one
Rack taken, kit missing, or it does not suit you. These are the swaps the app offers, matched by movement pattern and body region — each with the reason it is a fair substitute.
| Alternative | Why it works as a swap |
|---|---|
| Back Extension (45°) | Posterior chain with no axial load |
| Reverse Hyperextension | Machine: glute + hamstring with traction on the spine |
| 45° Hyperextension | Machine: posterior chain through full range, no axial load |
| Cable Pull-Through | Machine: cable-loaded hinge — hamstring + glute squeeze |
This exercise, in a program that knows why it is there
Train Smart puts this movement in the right session, at the right point in your block, at a weight calculated for you — and swaps it automatically if you do not have the kit.
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