A treasure trove of info here in these links:

http://www.ama-assn.org/meetings/public/annual99/reports/csa/rtf/csa3.rtf

"One kinematic analysis of the mechanical properties of a boxing punch from a professional heavyweight estimated a peak force on impact of 0.4 ton delivered at a velocity of 8.9 meters/sec, which represents a blow to the head approaching 0.63 ton. The latter is equivalent to swinging a padded wooden mallet with a mass of 6 kg at 20 miles per hour.22 Force is transmitted to the skull (causing transient deformation), which can cause contact trauma or focal contusions in the cerebral hemispheres beneath the point of cranial impact. Observational and cross-sectional studies have found that serum concentrations of enzymatic markers of central nervous system neurons and astrocytes are significantly elevated in boxers immediately after completing bouts, perhaps signaling acute damage to these cell types and disruption of the blood brain barrier."


http://news.bbc.co.uk/1/hi/wales/6529755.stm


http://www.bepress.com/jqas/vol2/iss2/3/

"Despite considerable research into boxing, surprisingly little is known concerning the fundamental physics of forces delivered in a boxing match. Most previous punch force estimates have been obtained from laboratory studies in which an experienced boxer struck an inanimate object. This paper presents the first direct measurement of punch force in professional boxing matches. Measurements were made using a proprietary system that records the force associated with punch impact. Twelve boxers wore boxing gloves incorporating the bestshot System TM in six professional boxing matches across five different weight classes. The force of each delivered punch was measured across all rounds of all bouts. Mean punch forces delivered ranged from 866.6 N (Super Middleweight) to 1149.2 N (Light Middleweight) across the fights and was not significantly correlated with boxer’s weight. In each of the three bouts where the outcome was determined by judges’ decision, the boxer delivering the greater cumulative force and the greater number of punches won unanimously. These measurements, the first direct measurement of punch force in professional boxing matches, are considerably less than those found in laboratory demonstrations, and likely reflect the dynamic nature of the ring. The ability to measure punch force directly may be beneficial in training, judging, and monitoring the health of boxers during competitive matches."


http://www.ingentaconnect.com/content/tandf/rjsp/2000/00000018/00000006/art00009

"The repeatability and accuracy of the dynamomoter were assessed using simulated straight punches. Discrimination efficacy was assessed by comparison of the maximal punching force of seven elite, eight intermediate and eight novice boxers during simulated boxing, throwing straight punches. For the elite, intermediate and novice groups, respectively, the maximal straight punching forces (mean ± sx ¯ ) were 4800 ± 227 N, 3722 ± 133 N and 2381 ± 116 N for the rear hand, and 2847 ± 225 N, 2283 ± 126 N a d 1604 ± 97 N for the lead hand. For all groups, maximal forces were larger for the rear than the lead hand ( P < 0.001). Maximal punching force was greater in the elite than the intermediate group, and greater in the intermediate than the novice group ( P < 0.05). The boxing dynamometer discriminated eff ectively between punching performance at three standards of performance and between the punching force of the rear and lead hands."

http://bjsm.bmj.com/cgi/content/full/39/10/710

"Methods: Seven Olympic boxers from five weight classes delivered 18 straight punches to the frangible face of the Hybrid III dummy. Translational and rotational head acceleration, neck responses, and jaw pressure distribution were measured. High speed video recorded each blow and was used to determine punch velocity. Equilibrium was used to determine punch force, energy transfer, and power.
Results: Punch force averaged 3427 (standard deviation (SD) 811) N, hand velocity 9.14 (SD 2.06) m/s, and effective punch mass 2.9 (SD 2.0) kg. Punch force was higher for the heavier weight classes, due primarily to a higher effective mass of the punch. Jaw load was 876 (SD 288) N. The peak translational acceleration was 58 (SD 13) g, rotational acceleration was 6343 (SD 1789) rad/s2, and neck shear was 994 (SD 318) N."

" The principles of momentum and energy conservation have been used to estimate the force of various punches and to understand what causes head injuries in karate and boxing. Peak punch forces are reported to range from 1666 to 6860 N.3 Walker4 estimated that a force of 3200 N is required to break a brick, which is common practice in karate demonstrations. However, in many studies the momentum of the punch was not transferred to an object comparable in mass and biofidelity to the human head and neck, and thus the risk of injury cannot be estimated from these punches.

In a study of karate, Smith and Hamill5 measured the fist velocities from punchers of different skill levels and the relative momentum of a 33 kg punching bag. Punches to the bag with bare fists (BF), karate gloves (KG), and boxing gloves (BG) were recorded with high speed film. The mean bag momentum for all tests was 47.37 Ns. The results showed no significant differences in fist velocities between skill levels or glove type (BF: 11.03 (standard deviation (SD) 1.96) m/s, KG: 11.89 (SD 2.10) m/s, BG: 11.57 (SD 3.43) m/s). The average fist velocity was 11.5 m/s. Differences in bag momentum were found with changes in skill level and glove. Greater bag momentum was generated with boxing gloves (53.73 (SD 15.35) Ns) than with either bare fists (46.4 (SD 17.40) Ns) or karate gloves (42.0 (SD 18.7) Ns), which had approximately the same momentum. The bag momentum was also greatest for the highest skilled subjects (60.8 (SD 17.3) Ns) compared to the lower skilled punchers (42.3 (SD 11.6) Ns) even though their respective fist velocities were approximately the same. The authors hypothesised that the increase in bag momentum was due to the skilled boxer’s ability to generate a greater effective mass during the impact than the lower skilled boxers. With a fist velocity at 11.5 m/s immediately before impact and the resultant bag momentum of 47.4 Ns, the effective mass of the striking fist was estimated to be approximately 4.1 kg. This is greater than the mass of the hand and reflects the ability to link more of the arm mass into the punch."

http://www.primidi.com/2007/06/24.html

"Ricky 'The Hitman' Hatton retained yesterday his IBO Light Welterweight boxing title by beating Jose Luis Castillo in four rounds in Las Vegas. Is this because he really hits his opponent very hard? According to engineers from the University of Manchester, the answer is a definitive yes. They showed that he packs a mighty punch by putting sensors in his punching bag. And they measured that he hits the target with an instantaneous force of about 400 kg. Not only he hits hard, but he is fast: the researchers clocked his movements at 32 mph (more than 50 kph). Hats off to Hatton, but I wouldn't like to meet him -- at least in a ring..."

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"In case you ever wondered what it's like to be knocked out, it's like waking up from a nightmare only to discover it wasn't a dream." -Forrest Griffin