Based on the biomechanical analysis of your Left-Leg Forward Bulgarian Split Squat, here is the elite-level breakdown focusing on spinal mechanics, pelvic alignment, and injury prevention.
ACTIONABLE STEPS (Priority Order)
- 1Correct the "Hip Hike" (Pelvic Obliquity): The most critical issue is your right hip (rear leg side) hiking significantly higher than your left hip during the descent.
* The Cue: "Imagine a spirit level across your hips. As you descend, intentionally drop your right hip pocket toward the floor to keep the bubble in the middle."
- 2Engage Left Glute Medius to Prevent Valgus: Your left knee collapses inward (dynamic valgus) as you drive up out of the hole (visible at 00:29).
* The Cue: "Push your left knee outward against an imaginary band" or "Rip the floor apart with your left foot" as you stand up.
- 3Neutralize the Rib-to-Pelvis Connection: You are crunching your right side (shortening the distance between right rib and right hip) to stabilize.
* The Cue: "Elongate your right waist. Keep the distance between your right armpit and right hip long throughout the rep."
- 4Lower the Rear Foot Elevation: The current bench height appears too high for your current hip flexor mobility, forcing the pelvis to tilt to compensate.
* The Adjustment: Use a lower step-up box or stack 2-3 bumper plates for the rear foot instead of a full bench.
FORM OVERVIEW & SCORE
Form Quality Score: 6.5/10
While leg strength and depth are solid, the movement is heavily compensated by pelvic tilting and lateral spinal flexion. You are completing the reps through muscular force, but the structural alignment (stacking) is compromised, placing shear force on the lumbar spine and SI joint.
- Spinal Integrity: 5/10 (Significant lateral flexion/compression on right side)
- Movement Symmetry: 6/10 (Pelvic drop on working side)
- Tempo Control: 8/10 (Controlled eccentric)
- Range of Motion: 9/10 (Good knee flexion depth)
DETAILED ANALYSIS
Setup Position
- Stance Width: Good. You have enough width to balance, though the rear foot placement seems slightly aggressive in height.
- Torso Alignment: At 00:00, the shoulders are relatively level, but the right hip is already starting to elevate before the movement begins.
Eccentric Phase (The Descent)
- 00:02 - 00:03: As you descend, the Trendelenburg Sign appears. Your left hip (working side) drops, and your right hip (rear side) hikes up.
- Muscular implication: This indicates the Left Glute Medius is not firing hard enough to stabilize the pelvis, and the Right Quadratus Lumborum (QL) is overactive, hiking the hip to compensate for tight hip flexors on the right leg.
- Tempo: Descent is controlled (approx 2 seconds), which is good for hypertrophy.
Transition/Bottom Position
- 00:04 & 00:18: At maximum depth, your lumbar spine is laterally flexed to the right. This creates a functional "C" curve in the lower back (concave on the right, convex on the left).
- Rear Leg Mechanics: The rear knee is tracking well, but the height of the bench is likely forcing your lumbar spine into extension and rotation because the rectus femoris (quad/hip flexor) on the rear leg is running out of length.
Concentric Phase (The Drive)
- 00:05 & 00:29 (Critical): As you initiate the drive upward, there is a distinct Knee Valgus (inward collapse) of the left knee. The knee tracks inside the big toe. This places stress on the MCL and meniscus.
- Power Leak: This valgus collapse signals that the glute max/med are letting the adductors take over the movement.
Lockout/Top Position
- 00:07: You return to a relatively stacked position, but the pelvis never fully neutralizes. You remain slightly hitched on the right side even at the top.
Rep-to-Rep Consistency
- Fatigue Pattern: By 00:36 and 00:45, the knee cave becomes more pronounced, and the reliance on the "hip hike" strategy increases. You are consistent in your movement pattern, but you are consistently reinforcing a dysfunctional asymmetry.
Scoliosis & Spinal Considerations
- Observation: Your movement pattern mimics a functional lumbar scoliosis with a convexity to the left.
- Risk: By allowing the right hip to hike and the torso to crunch to the right, you are compressing the right side facets of the lumbar vertebrae. If you have a pre-existing curve, this form is feeding into it rather than correcting it.
- Correction: You must fight to keep the torso perpendicular to the floor. Do not lean away from the working leg.
Injury Risk Assessment
- Lumbar Spine (Moderate Risk): The lateral shift places uneven pressure on the discs.
- Left Knee (Moderate Risk): Repeated valgus collapse under load is a primary mechanism for patellofemoral pain and ligament stress.
- Right SI Joint (Low-Moderate Risk): The shearing force created by the pelvic tilt can irritate the SI joint on the rear leg side.
Programming Recommendations
- 1Regression (Immediate): Switch to a Split Squat (both feet on floor) or a Low-Elevation Split Squat. This will remove the hip flexor restriction and allow you to learn how to keep the pelvis level.
- 2Corrective Primer: Perform "Clamshells" or "Glute Bridges" immediately before this lift to wake up the glute medius.
- 3Accessory Work:
* Suitcase Carries: Walk holding a heavy dumbbell in one hand. This trains the QL and obliques to resist lateral flexion (anti-lateral flexion core work).
* Single-Leg RDLs: To improve hip stability without the rear leg constraint.
- 4Mobility: Couch stretch for the right hip flexor/quad to reduce the pull on the pelvis during the split squat.