Is it possible to land a punch at 2,000 pounds per square inch?

July 23, 2010

Dear Cecil:

In the movie Rocky IV, Ivan Drago registers a 2,150-psi punch. That seems unrealistic to me, and yet I’m hearing Internet rumors about MMA fighters and boxers coming close to that number. Is it possible to throw a punch that hard? What would that sort of power do to someone's face?

Cecil replies:

The Rocky movies are fiction, Dave. That tells you pretty much all you need to know. But let me add some details.

First we need to clear up the difference between force and pressure. Force is what causes something to accelerate, e.g., a fighter’s head in the direction of a thrown punch. In the U.S. force is normally measured in pounds. Pressure is force per unit of contact area, commonly expressed in pounds per square inch (psi). When researchers study punching ability they usually focus on force rather than pressure, since the pressure varies as the contact area expands on impact.

With that in mind, let’s look at the research:

  • A study of seven Olympic boxers in weight classes ranging from flyweight to super heavyweight showed a range of 447 to 1,066 pounds of peak punching force. Energy transferred from punch to target varied widely depending on how heavy the boxers’ hands and gloves were, how fast they punched, and how rigidly they held their wrists. The three flyweights, interestingly, delivered more oomph than all but the two super heavyweights.
  • A study of 70 boxers found elite-level fighters could punch with an average of 776 pounds of force. Another study of 23 boxers showed elite fighters were able to punch more than twice as hard as novices, the hardest hitter generating almost 1,300 pounds of force.
  • An oft-cited 1985 study of Frank Bruno, who'd go on to be WBC heavyweight champ, showed he could punch with a force of 920 pounds in the lab. Researchers extrapolated that to a real-life blow of 1,420 pounds, enough to accelerate his opponent’s head at a rate of 53 g — that is, 53 times the force of gravity.
  • Martial arts punches generally involve much less force than those in boxing. A study of 12 karate black belts showed so-called reverse punches delivered an average force of 325 pounds, with the strongest measuring 412 pounds. Short-range power punches averaged 178 pounds. Another study found martial artists needed 687 pounds of force to break a concrete slab 1.5 inches thick. One early researcher estimated karate strikes could reach 1,500 pounds, but that figure was an outlier.

If a punch thrown by Rocky IV villain Ivan Drago is supposed to measure 2,150 psi and his glove’s impact area is something like four square inches, he’d be exerting a force of 8,600 pounds, or more than four tons. Based on the professional literature, no boxer in real life comes anywhere close to that. I did find a 2007 news account about WBO cruiserweight champion Enzo Maccarinelli, whose punches supposedly packed a wallop of around 3.85 tons. However, the researchers making this claim have yet to publish their findings in a scientific journal, and I’m not taking them seriously until they do.

Even without Drago in the ring, boxing is a punishing sport, especially where the head is involved. Damage comes from three things: (1) the impact itself, which may be manifested in, say, a broken jaw; (2) acceleration to the brain leading to abrupt contact with the skull, possibly resulting in concussion; and (3) the rotational force that twists the brain within the skull, increasing the severity of injury and the likelihood of a knockout.

One metric for gauging the risk and seriousness of a brain injury is the Wayne State tolerance curve, which looks at both the g-force imparted to the head and the span of time involved. Generally speaking you don’t want to take a shot of more than 50 g, although you can stand more if the impact is really brief — say, a couple thousandths of a second. If you're on the receiving end of a Bruno-class impact, my guess is you won't soon get up.

Punches to the head can cause detached retinas, brain hemorrhage, fractured bones, and permanent neurological disorders. As I’ve mentioned before, something like a fifth of boxers suffer from dementia pugilistica, the consequence of repeated blows to the skull; it's characterized by slurred speech and halting gait. Worse can happen. According to one estimate, boxing killed at least 650 fighters from 1918 through 1997.

Mixed martial arts (MMA) fighters, interestingly, seem to be less at risk. Since MMA rules allow grappling (meaning less punching) and tapouts (giving up), actual knockouts occur only half as often as in boxing.

Besides maybe getting killed, cumulative brain damage is the scariest part of boxing, as most fighters now recognize. To quote Terry Marsh, the undefeated light welterweight champion, “I don't need the British Medical Association to tell me getting hit on the head can't do me any good." Muhammad Ali would surely concur.

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References

American Medical Association, Council on Scientific Affairs. CSA Report 3-A-99. Boxing Injuries (Resolutions 404 and 423, A-97).

Atha, J. et al. “The Damaging Punch” British Medical Journal 291 (1985): 1756-1757.

Bledsoe, Gregory H. et al. “Incidence of Injury in Professional Mixed Martial Arts Competitions” Journal of Sports Science and Medicine (2006): 136-142.

Bolander, Richard P. “The effects of height and distance on the force production and acceleration in martial arts strikes” Journal of Sports Science and Medicine 8 (2009): 47-52.

Corsellis, J.A.N. “Boxing and the Brain” British Medical Journal 298 (1989): 105-109.

Feld, M. S. et. al. “The Physics of Karate” Scientific American (April, 1979): 150-158.

Gulledge, J. Keith. "A Comparison of the Reverse and Power Punches in Oriental Martial Arts" Master's Thesis, School of Health, Physical Education, and Recreation, Indiana University, March, 2007.

McCann, Steven Ward. Kinematic analysis of the gyaku-zuki (reverse punch) in zenkutsu-dachi (front stance). Diss: San Jose State University, 1992.

Reilly, Peter and Bullock, Ross, eds. Head Injury London: Chapman & Hall, 1997. Chapter 2: Biomechanics of Closed Head Injury, McLean, A.J. and Anderson, Robert W.G.

Rist, Chris. “The Physics of…Karate” Discover (May, 2000).

Smith, M.S. et al. “Development of a boxing dynamometer and its punch force discrimination efficacy” Journal of Sports Sciences 18.6 (2000): 445.

Walilko, T.J. et al. “Biomechanics of the head for Olympic boxer punches to the face” British Journal of Sports Medicine 39 (2005): 710-719.

Wasik, Jacek. “Chosen aspects of physics in martial arts” Archives of Budo 5 (2009): 11-14.

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