The Swing That Becomes a Back Extension
Priya, 34, 63 kg, has 10 weeks of kettlebell experience. During a 5-round swing session with a 20 kg bell (15 reps, 45 seconds rest), her low back tires by round 3. Side video shows: at the bottom her knees track forward and her shins pass vertical before the bell reaches knee height; the bell drops only to knee height instead of between the thighs; her torso is near horizontal and her lumbar spine extends as the bell rises; her arms visibly pull the bell at the top. She reports no pain but 'tightness' at L4–L5 after sessions. She deadlifts 70 kg with good form and can hip-hinge to a 12-inch box. She wants to reach 24 kg in 4 weeks and is training for a half marathon.
1. Rank the faults by priority and explain the biomechanical consequence of each.
Read the worked answer
- Bell path and hinge timing. The bell at knee height and shins vertical means the hinge is too shallow and the bell is too far forward. The lumbar extension is a compensation to keep the bell from pulling her forward; repeated, it loads the posterior chain with shear. Fix this first.
- Arm pull at the top. Pulling with the arms shortens the pendulum and encourages lumbar extension. It also reduces the hip snap.
- Knee tracking forward. Early knee bend turns the swing into a squat and changes the bell arc.
Prioritize fault 1, because it drives faults 2 and 3. The L4–L5 tightness is a load-tolerance signal, not a diagnosis.
2. Provide a three-cue sequence for the next session, plus one drill and one constraint. Explain why each cue is external and short.
Read the worked answer
- 'Push the bell back between your thighs' - external, directs the hinge.
- 'Snap your belt buckle to the wall' - external, drives hip extension.
- 'Let the bell float; your arms are ropes' - external, removes the pull.
Drill: towel swing - hold a towel with both hands and swing it back between the legs; it teaches the bell path without load. Constraint: 16 kg, 10 reps, 6 rounds, 60 seconds rest. Video from the side for feedback. Cue one thing at a time; do not stack all three in the same rep.
3. What evidence would make you progress to 24 kg, and what would make you regress?
Read the worked answer
Progress when, for 3 consecutive sets of 10 at 16 kg: the bell reaches mid-thigh height at the back, lumbar position is unchanged from set 1 to set 3, she reports no L4–L5 tightness, and RPE is ≤7. Then add sets, not load. Move to 20 kg only after she can complete 5×12 with stable video and no symptoms for two sessions.
Regress to deadlift and hinge drills if lumbar extension returns or symptoms last beyond the session. The half-marathon goal means preserving energy for running; do not chase 24 kg in 4 weeks.