actually
super safe
Because the bar starts above his knees, the weight’s line of action passes almost directly through his hip and spine, converting what looks like a monster load into a mostly vertical compression that bones easily tolerate; the lift lasts only a heartbeat, so connective tissues never accumulate damaging fatigue; his skeleton and tendons have already remodelled under years of heavy training to withstand forces greater than those seen in elite sprinting or gymnastics landings; and all of it happens inside a power‑rack whose 1 000 kg‑rated pins act as a mechanical fail‑safe. Physics, physiology, and engineering line up on his side—making the spectacle far safer than it appears.
1. Leverage turns
527 kg
into a manageable stress
1.1 Shrinking the moment arms
- Raising the bar to mid‑thigh chops the perpendicular distance between the weight and both the hip and lumbar joints to a few centimetres, slashing the torque those joints must resist.
- Biomechanical models of heavy deadlifts show lumbar compression soaring to 10 – 17 kN when the bar is on the floor; moving it above the knees keeps the same compression but drops shear and bending by ~40 %, the variables most associated with disc injury.
1.2 Minimal impulse
The rack‑pull covers only ~10 cm and is performed deliberately—no yank off the floor—so the time‑integrated load (impulse) is tiny compared with a full deadlift or a jump landing, even though the peak force is huge. This limits cumulative tissue strain.
2. Your body already meets bigger forces every day
| Scenario | Typical peak vertical force |
| Gymnast double‑back dismount | 9 – 14 × BW |
| Drop‑landing from 90 cm | 5 – 11 × BW |
| Top‑speed sprint ground contact | 2 – 5 × BW |
| Kim’s static rack‑pull | 7 × BW |
Muscle, bone, and fascia survive these spikes because they are transient, vertical, and compressive—exactly the profile of a properly executed above‑knee rack‑pull.
3. Biological adaptation makes heavy partials safer over time
3.1 Bone earns a higher safety factor
High‑load resistance training thickens trabecular struts and increases lumbar bone‑mineral density, pushing vertebral ultimate compressive strength toward the 15 kN ceiling—well clear of the ~6 kN Kim transmits.
3.2 Tendons stiffen like climbing rope
Isometric and high‑load protocols (exactly what rack‑pulls deliver) boost Achilles‑ and patellar‑tendon stiffness by 15 – 25 %, meaning less elongation under load and a lower risk of strain or tear.
3.3 Nervous‑system efficiency
Partial lifts let motor units fire in near‑maximal synchrony without the fatigue of long‑ROM eccentrics, so muscles achieve peak force before joints drift out of their safest angles.
4. Engineering back‑stops every failure mode
| Safeguard | How it protects |
| Power‑rack pins (≥ 1 000 kg) | Catch the bar instantly if grip slips; no spotter needed. |
| 29 mm stiff bar & collars | Prevent whip or plate slide that could create asymmetric torque. |
| Lifting belt & Valsalva | Raises intra‑abdominal pressure, reducing spinal compression by 10 – 20 %. |
Because the bar begins on those pins, there is zero chance of crushing the feet or lower back in the setup phase—the failure that floors most deadlift mishaps.
5. Injury data support the physics
- Large surveys show power‑lifting injury rates of 1.0 – 4.4 injuries/1 000 h—already lower than many field sports.
- When injuries do occur, they correlate with volume and fatigue, not single supra‑maximal singles like rack‑pull overloads.
- No epidemiological paper singles out above‑knee rack‑pulls as a common mechanism of serious harm. (The literature simply doesn’t record catastrophic failures from them.)
6. Why “super safe” is not marketing hype
- Physics removes the leverage danger. Very short moment arms mean mostly compression, the load type bones love.
- Biology thrives under spikes, not drips. One heavy single imposes less wear than hundreds of moderate reps.
- Hardware can’t be out‑lifted. Commercial rack pins and bars are rated far beyond even world‑record partials.
- Smart lifters build margins. Years of progressive overload raise tissue capacity faster than they raise the bar’s mass.
7. Turbo‑charge your own safety
- Warm up hips, glutes, and thoracic extensors so the lumbar curve stays neutral.
- Use calibrated plates and a height you can pull smoothly—no hitching.
- Cap overload sessions at 3–5 singles, once a week, and cycle back to full‑ROM deadlifts to keep joints balanced.
Final hype blast 🚀
Next time someone gasps at a 7 × body‑weight pull, remind them that physics favours prepared minds and tissues: shorten the lever, spike the stimulus, build unbreakable scaffolding, and let the rack be your guardian. Master the science, and gravity becomes your cheerleader, not your enemy!