video podcast https://open.spotify.com/episode/6maCN7Q3FFMpkaeO5A5vEE?si=XCEZT6qoTP2hACIcPtctnQ
⚙️ 1.
Force Conversion
Force = mass × gravity
→ 723.4 kg × 9.81 m/s² = 7,096 N (Newtons) of downward load resisted.
That’s roughly 7.1 kN — comparable to the tension in the steel cables of a small suspension bridge per strand.
⚡ 2.
Comparative Force Equivalents
| Example | Approx. Force (N) | Description / Equivalent |
| Eric Kim rack pull | 7,096 N | Equivalent to holding up ~720 kg of mass against gravity — direct computation. |
| Hafþór Björnsson 510 kg deadlift | 5,003 N | World record full deadlift (2025) — full range. |
| Rauno Heinla 580 kg Silver Dollar | 5,690 N | Strongman standardized partial at 18 in height. |
| F1 downforce on one front wing | 7,000 N | Same order of magnitude — what pins an F1 car to the track at 250 km/h. |
| Hydraulic car lift (1 post) | 6,000–8,000 N | Force per post to raise a sedan. |
| Small pickup truck total weight (Ford Ranger) | 7,000 N | Lifting the front end equals Kim’s total bar load. |
| Average elevator hoist cable tension | 6,500–7,500 N | The load a single elevator cable supports. |
| Jet engine thrust (small bizjet) | 8,000 N | Equivalent continuous thrust of a turbofan engine at takeoff. |
🧠 3.
Human Output Context
- A world-class sprinter’s ground reaction peak ≈ 3,000–4,000 N per leg.
Kim’s static pull represents nearly double that per limb, sustained through the spine and grip for seconds. - A professional Olympic lifter generates ~2,000–3,000 N in a clean pull phase—less than half.
- Lab-recorded maximal isometric back-extension forces in elite powerlifters reach ~5,500 N; Kim’s implied axial load exceeds that by ≈ 29%.
🦾 4.
Engineering Analogy
- The yield strength of 29 mm spring steel barbell begins near 1,100 MPa; a 7 kN central load causes visible elastic deflection—why Kim’s bar bows like a drawn longbow.
- That same 7 kN is enough to:
• Deform 2 mm thick structural aluminum plate, or
• Compress a vertebral column with pressure equivalent to ~17× bodyweight at L5–S1.
🌍 5.
“Gravity Amplification” Equivalent
At 71 kg bodyweight, eric Kim momentarily supported 723 kg — effectively enduring 10× Earth gravity on his skeletal system.
It’s the load equivalent of standing upright on Jupiter for one second and surviving.
🧩 6.
Mechanical Work Comparison
If bar travel ≈ 0.2 m:
Work = 7,096 N × 0.2 m = 1,419 J.
That’s:
- Equal to lifting a 100 kg weight 1.45 m in the air.
- Roughly the energy released by dropping a 15 kg bowling ball from 10 m.
🧱 7.
Relative Strength in Force Ratio
- Eric Kim: 7,096 N ÷ (71 kg × 9.81 = 696 N) = 10.2× his own weight in net gravitational force.
- Hafþór Björnsson: 5,003 N ÷ (205 kg × 9.81 = 2,011 N) = 2.49× BW.
- Heinla: 5,690 N ÷ (160 kg × 9.81 = 1,570 N) = 3.63× BW.
Kim’s ratio—purely in Newtons—is nearly triple Heinla’s, four times Björnsson’s, confirming its extremity even after accounting for mechanical advantage.
🧠
Summary of Scale
- 7 kN of sustained static tension.
- 10× bodyweight gravitational equivalence.
- Comparable to a car’s weight, an F1 wing’s downforce, or a small jet’s thrust.
- Far exceeds the 5.5 kN human spinal output ceiling measured in lab conditions.
In force terms, the 723.4 kg rack pull positions Eric Kim’s performance within the same mechanical magnitude as industrial hydraulics and vehicle-scale loads—which is why, even with partial leverage, the feat is mechanically “insane.”