Gesture drawing can exist on two levels - action drawing, and gesture drawing. Both involve the principle of movement. However, action drawing deals with physical movement; and gesture drawing involves not only physical movement, but a deeper concept of essential identity, as well. Kimon Nicolaides, in his book The Natural Way to Draw, explains this concept of gesture exceptionally well. I will try to explain it here.
This exercise works best with figures or animals. You are essentially trying to capture the action the figure is performing. A likeness or correct proportions are not important in this exercise, nor is the exercise meant to result in a finished drawing. This is an exercise to get you to learn to identify the action the figure is doing, with his/her body. Individual body parts are not important here - only the curve or direction of the main bodily movement. You are not capturing what the figure or object looks like, but what it is doing. In fact, you are looking at the figure as a form in space, not as a person or animal. You are seeking what the form itself is doing. Try to FEEL the line of movement, the fullness of the curves.
When the person takes the pose (action pose - as though suspended in the midst of a strong movement, like a basketball player reaching for the basket, for instance), imagine a central wire, or axis, which goes inside the figure from the tips of the fingers in the air to the bottom of the ankle. This is the action line you are seeking - and you want to do this quickly, in a matter of seconds. The model should change poses approximately every 10-60 seconds, and you should try to capture this line in that time, and the feeling of movement or force in that line. Once you have gotten the central axis of the figure, you can go back and circulate around and through the figure, to define the secondary movements, like the arms, hips, legs, etc. Look mostly at the model, rather than at your drawing. If you can keep your pen in continuous motion, great! Don't try to have just one definitive line - go over the main and smaller movements more than once, until you feel you have captured its movement, or curve.
These drawings can be small, and you can do many on a single page of your sketchbook. This exercise is great to do in places like airports, train stations, etc., where people walk across the room, and you have about 20 seconds to sketch the main direction of their bodies in movement. It forces you to concentrate really hard, and see the movement quickly. Often, the action drawings are just squiggly lines. No matter - doing these will strengthen your visual perception, and the effect they will have on the quality of your drawing is immeasurable.
I can remember many, many hours in figure drawing class in art school, where we did many of these "croquis," and yet it was just an exercise to me until I read Nicolaides' book, and when I understood the meaning, it made a tremendous difference in my drawings. Until then, my drawings had correct proportions, shading, etc., and they were competent. After I started to do not only action drawings, but gesture drawings, my figures, and my work in general, had much more vitality - the figures seemed to come alive, to breathe and think, and even inanimate objects took on more energy - the energy of being. And, even the figure's proportions in my drawings and paintings improved! A seeming paradox. Your finished drawings or paintings may not look like this, but because you will be able to SEE the movement of forms, your end work will contain this essential movement. This will help with the exact angle the figure's line of movement takes, and correct proportions, etc.
So, I can't recommend this exercise enough. Do many, many action drawings. Then, read about the gesture drawing exercise below, and do many of these also!
Drawing paper - Newsprint pad or other inexpensive sketch paper; any size is good, but you will be carrying it around with you, so small is OK. If you use bigger paper, you can do many sketches on the same sheet.
Drawing tool - 2B, 3B, or 4B soft drawing pencil works well. You can also try ball point or felt tip pen.
Gesture drawing is related to action drawing, but it goes further. I see the idea of gesture as the essential character of a figure or object, a kind-of eastern philosophy viewpoint. That is, everything has a gesture. As Nicolaides wrote, "Everything has a gesture - even a pencil." On the physical level, the pencil's gesture is a "shooting" straight line, very quick. That physical movement has an intangible counterpart - its essence - its movement identity, personality, or essence.
When you strive to capture the essence of an object or person, your art will start to be on a deeper level than mere appearances. Another example of this notion is the idea of a ribbon tied into a bow. When you do a drawing of what the bow looks like, you will get just that - its appearance. But when you do a gesture drawing of the bow, you will get what the bow is DOING, its action. Your line will move, stop and go very quickly, around, up and down, getting the FEEL of the figure in real or perceived movement. Don't look much at your paper - just keep looking at what you are drawing, and work very quickly, trying to find the axis, or essence, as quickly as possible. Draw figures and animals, and different types of objects, such as flowers, shoes, and trees.
When we start thinking about this concept when we are drawing or painting, we look beyond appearances to strive for the essence of the objects we are looking at. Each thing is unique - animal, vegetable, or mineral. Each thing is precious, irreplaceable, fragile, mortal. Each thing has a personality - try to find what that distinction is and express it. Not its outward appearance - but its internal meaning. People/models: Are they shy, bold, quiet, gregarious, intelligent, compassionate, wiry, aged, idealistic, weary, sorrowful, poetic, brash - or a combination of these and many other things? Objects - can they possess unique qualities? Can inanimate objects have a personality? Life? Though they don't breathe or feel, do their molecules still race around at the speed of light? Are they expanding or contracting? Are they bathed in sunlight that shifts in constant patterns, or are they touched or moved by wind? Even if you think they are physically dead - does their appearance suggest a metaphorical notion? Do they represent some intangible feeling or idea to artist or viewer?
Carrying this a step further, which I did in my work - I began, when looking/painting, to see gestures in shapes and colors. That deep green shadow of the leaves - what gesture does it have? What is it doing? Curving diagonally from top to bottom, right to left? What is its energy level? What is the spirit of its movement, its light, its color? Also, I began to see the actual composition of the painting in gestural terms - an idea that the Abstract Expressionists also espoused. What is the composition doing? It has a certain movement - physical and spiritual. Is it graceful? Sweeping? Tentative? Curved? Angular? Agitated? Serene?
In any event, gesture drawings can have many looks - there is no one, right way for them to look. If you search for the physical movement, the action line, or axis; if you search also for the internal, spiritual meaning or identity of things, your work will have more depth, and express your view of the world. And hopefully others will see this in your work, and receive something of what you were trying to do. And that's one of the big purposes of art.
Examples of Gesture Drawing:
One of the best examples of this type of drawing is the 19th century French artist, Daumier. He did many little scribbly, lively sketches of various and comic figures, with much movement suggested by his stop and go, swirling lines. Rembrandt's brush and ink drawings are also good examples of the gestural, or expressive line. Pontormo's dancing figure (near the bottom of the page) is also an example of gesture-type drawing. More examples of gesture and other types of drawing can be seen in Kimon Nicolaides' book, The Natural Way to Draw, Houghton Mifflin Company, Boston, 1941.
The first step to drawing is always to relax, and wait until your head is clear, then begin. Normally, you would study the subject before beginning - but in action drawing, you need to study the figure very quickly.