F = ma; ma ≠ F

I am writing an article on the science behind striking and kicking techniques to be published in the Journal of Asian Martial Arts.

In researching the science behind striking and kicking techniques in the martial arts literature, I have come across the frequent use of the mechanical concept of force. Force (F) is calculated as the produce of mass (m) and acceleration (a): F = ma.

It is frequently explained that, based on this formula, an increase in mass and/or acceleration of a strike or kick will increase the force of that strike or kick.

Sprague, in Fighting Science: The Laws of Physics for Martial Artists (2002), suggests that the force will be greater if both mass and acceleration are large. When referring to the force formula, Sprague suggests that we can see why power seems to increase with weight and speed, and why full contact fighting, like boxing and kick boxing, utilise weight classes. Starr, in Martial Mechanics: Maximum Results With Minimum Effort in the Practice of the Martial Arts (2008), suggests that the more you have of mass and acceleration, the more force you will generate. Belonoha, in The Wing Chun Compendium, Volume 2 (2009), likewise suggests that the force formula indicates that more mass and acceleration in a wing chun punch generates more force. Central Ohio Martial Arts (http://www.centralohioma.com/Physics/Force.php) suggest that to 'increase force, either a martial artist has to increase his mass or his acceleration.'

No, no, no! The F = ma formula does not say that if you increase mass or acceleration in a strike or kick you increase the force of that strike or kick. It says that when a force is applied to a body or object it can cause the mass of that body or object to accelerate. It expresses a cause-and-effect relationship. Forces cause acceleration; and acceleration is the effect of forces. A force applied to an arm or leg (mass) causes it to accelerate towards a target. A force applied by a fist/hand or foot in a striking or kicking techniques applies a force to the other body or object causing it's mass to accelerate. It does not say that if you increase the mass or acceleration of that arm or leg that the force will be greater.

F = ma; ma ≠ F.

I state in my article that I'm not interested in the science for the sake of science. I'm only interested in the science behind striking and kicking techniques in so far as it informs practice, and only then if it facilitates the understanding and study of those techniques in a practical way. My review of the martial arts literature in this regards has to date yielded no positive results.

Does F = ma facilitate the understanding and study of striking and kicking techniques? Does the physical fact that a force applied to a body or object causes its mass to accelerate facilitate the understanding and study of striking and kicking techniques in a practical way. I'm going with 'no', until it can be demonstrated otherwise.

However, there are related concepts to force that can be used to facilitate the understanding and study of not only the striking and kicking techniques taught within your own martial art, but also those taught in other martial arts you are unfamiliar with and those used in violence generally. This is the benefit of understanding the science behind the techniques. It enables you to understand not only the techniques taught in your martial art but those taught in unfamiliar martial arts and those used in violence generally.

The purpose of this blog is two fold. First, to put paid to the misconception that increasing mass and/or acceleration in a strike or kick increases the force of that technique based on F = ma. Secondly, to ask 'So what?' whenever science is offered up to explain any techniques in the martial arts or used in violence generally. This the question I raised in virtually all explanations of striking and kicking techniques in scientific terms in the martial arts literature. This question then led me to injury science; a discipline that studies the subject at the very heart of all activities associated with preparing a person to survive a violent encounter. A discipline whose concepts and theories are applied every day in the real world in real ways. These concepts and theories have never, to the best of my knowledge, ever been applied to the tactics and techniques of the activities associated with preparing a person to survive a violent encounter - until now (in my article).