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Research into different aspects of martial arts competition.

Center of mass and judo throws

A three-dimensional analysis of the center of mass for three different Judo throwing techniques.
R. Imamura, A. Hreljac, R. Escamilla, and W. Edwards
Journal of Sports Science and Medicine (2006) 5 (CSSI), 122 - 131

Four black belt throwers (tori) and one black belt faller (uke) were filmed and analyzed in three-dimensions using two video cameras and motion analysis software. Average linear momentum in the anteroposterior (x), vertical (y), and mediolateral (z) directions and average resultant impulse of uke's center of mass (COM) were investigated for three different throwing techniques; harai-goshi (hip throw), seoi-nage (hand throw), and osoto-gari (leg throw). Each throw was broken down into three main phases; kuzushi (balance breaking), tsukuri (fit-in), and kake (throw).

Conclusions. For the harai-goshi and osoto-gari throws, impulse measurements were the largest within kuzushi and tsukuri phases (where the collision between tori and uke predominantly occurs). Both throws indicated an importance for tori to create large momentum prior to contact with uke. The seoi-nage throw demonstrated the lowest impulse and maintained forward momentum on the body of uke throughout the entire throw. Harai-goshi and osoto-gari are considered power throws well-suited for large and strong judo players. The seoi-nage throw is considered more technical and is considered well-suited for shorter players with good agility.

A form of resistance by uke was found during the kuzushi phase for all throws. The resistance which can be initiated by tori's push or pull allows for the tsukuri phase to occur properly by freezing uke for a good fit-in. Strategies for initiating an effective resistance include initiating movement of uke so that their COM is shifted to their left (for right-handed throw) by incorporating an instantaneous "snap pull" with the pulling hand during kuzushi to create an opposite movement from uke.

How boxers decide to punch

How boxers decide to punch a target: emergent behavior in nonlinear dynamical movement systems.
R. Hristovski , K. Davids, D. Ara├║jo, and C. Button
Journal of Sports Science and Medicine (2006) 5 (CSSI), 60 - 73

Previous research has shown how dynamical systems theory provides a relevant framework for investigating decision-making behavior in sport. The aim of this study was to adopt concepts and tools from nonlinear dynamics in examining effects of boxer-target distance and perceived punching efficiency on emergent decision-making during a typical practice task in boxing.

Conclusions. Results revealed the existence of critical values of scaled distances between boxers and targets for first-time appearance and disappearance of a diverse range of boxing actions including jabs, hooks, and uppercuts. Reasons for the diversity of actions were twofold:
  • Abrupt (qualitative) changes in the number of the possible punches, i.e. motor solutions to the hitting task;
  • Fine modification of the probabilities of selecting specific striking patterns.

Conclusions. Boxers were able to exploit the emerging perception of strike ability, leading to a changing diversity of selected actions and a cascade of abrupt changes in the perceptual-motor workspace of the task. The perceived efficiency of a punching action by the participants also changed as a function of the scaled distance to a target and was correlated with the probability of occurrence of specific boxing actions. Accordingly, scaled distance-dependent perceived efficiency seems an important perceptual constraint in the training task of punching a heavy bag in boxers.

Martial arts punches

A comparison of the reverse and power punches in oriental martial arts.
K. Gulledge
2006, Indiana University

Traditional martial arts punches, such as the reverse punch, rely on the acceleration of the combined mass of the arm and parts of the torso through a long range of motion to generate momentum for transfer to the target. However, the martial arts also use focused striking techniques that use of very small ranges of motion prior to impact, such as the three-inch "power punch" that begins with the knuckles of the punching hand about three inches from the target, and then drives directly into the target from this position without any countermovement. Some martial artists believe that the power punch is as potent as the reverse punch. This is surprising because the limited range of motion should not be expected to allow the fist to reach a large velocity before impact.

This study sought to find out if the power punch is as potent as the reverse punch, and if so, to find out what are the mechanical reasons for it.

Twelve expert male martial artists stood on a force plate, and executed reverse and power punches against a padded target. An infrared motion tracking system measured punch velocity and the force plate measured punch force.

Conclusions. The reverse punch produced larger velocities immediately before impact than the power punch. The peak force exerted by the fist was also larger in the reverse punch than in the power punch. However, the linear impulse exerted by the fist during the main part of the impact was similar in the reverse and power punches. The results suggest that the power punch is less potent than the reverse punch, but is similarly effective for throwing the opponent off-balance.

Power production in karate

Variation in resistive force selection during brief high-intensity cycle ergometry: implications for power assessment and production in elite karate practitioners.
J. Baker and B. Davies
Journal of Sports Science and Medicine (2006) 5 (CSSI), 42 - 46

The purpose of this study was to measure power values generated in 11 elite karate fighters during brief high-intensity cycle ergometry when resistive forces were derived from total - body mass (TBM) or fat - free mass (FFM). Body density was calculated using hydrostatic weighing procedures with fat mass ascertained from body density values.

Participants were required to pedal maximally on a cycle ergometer against randomly assigned loads for 8 seconds.

Conclusions. This study suggests that when high-intensity cycle ergometer resistive forces are derived from FFM, greater peak powers can be obtained consistently in karate athletes. Resistive forces that relate to the active muscle tissue utilized during this type of exercise may need to be explored in preference to protocols that include both lean and fat masses. The findings have implications for both exercise prescription and the evaluation of experimental results concerning karate athletes.

Boxer punches to the face

Biomechanics of the head for Olympic boxer punches to the face.
T. Walilko, D. Viano, and C. Bir
British Journal of Sports Medicine 2005; 39:710-719

A study of the biomechanics of the head for punches to the jaw and the risk of head injury from translational and rotational acceleration in Olympic boxers.

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.

Punch force averaged 3427 N, hand velocity 9.14 m/s, and effective punch mass 2.9 kg. Punch force was higher for the heavier weight classes, due primarily to a higher effective mass of the punch. Jaw load was 876 N. The peak translational acceleration was 58 g, rotational acceleration was 6343 rad/s2, and neck shear was 994 N.

Conclusions. Olympic boxers deliver straight punches with high impact velocity and energy transfer. The severity of the punch increases with the weight class.

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