Normal people usually stand on two legs. It gives them stability and redundancy of support. Dancers must stand differently from this. They have to stand on one leg. They may have the foot of the other leg in contact with the ground, but their weight is predominently on only one of their legs. This is because to dance they know that for every step of their dance, they must move one of their legs, and one cannot move a leg if one has weight on it. So for every moment of their dance, they ensure that their weight is on the leg that they are not moving (which I shall call the "standing leg").
Normal people step by putting out a leg and then smoothly transfering their weight from one leg to the other, with a significant period when the weight is distributed between the two legs. When dancers take a step, they ensure that the transference of their weight from one leg to the other has only the briefest of periods when the weight supported by two legs.
A normal person when taking a 'step', she/he will put her/his feet together, move one leg forward, and then close the other foot to it. For normal people, a 'step' starts and ends with the feet together.
But if you ask a person to clap their hands, he/she will start with his/her hands apart, bring them together for a clap, then separate them apart again. A 'clap' begins and ends with the hands apart. It is hard to think of a 'clap' starting and ending with hands together.
Different movements have different antecedents
So, before even starting to take a step, a dancer will separate the feet, typically either pointing one foot to the side or back, ensuring that the weight is completely on the standing leg. Only then will a dancer move the non-standing leg (the moving leg) forward to take the 'step', and there it ends with the previously standing leg still left pointing behind. For a dancer, because they are only standing on one leg at any one time, a 'step' starts and ends with the feet apart. There are three reasons for this.
What is the difference between marching and dancing? The answer is the turning. Marching is mainly about progression along straight lines. In marching, turning is infrequent. In dancing, going straight is infrequent. Our earliest Ballroom Dance, the Viennese Waltz, comes of course from Austria, where in German, "waltzen" amongst other things means "to turn". Dancing involves turning. We may even spin on the spot, or else change alignment as we step, so tracing a curved pattern on the floor, or we may just turn the body, so moving in one direction while facing another direction.
So the first reason that a step for a dancer begins and ends with feet apart is that it gives a dancer the ability to turn during the 'step', as follows. When the feet are apart, the dancer has a larger moment of inertia about a vertical axis than when the feet are together. So if the dancer initiates a turning movement at the beginning of the step, giving the body some angular momentum about the vertical axis, then as the moving foot passes the standing foot, the moment of inertia decreases, and the rate of turn will increase by conservation of angular momentum. As the moving foot then continues to its final position, the inertia increases again so the rate of spin will decrease, allowing the dancer to end the 'step' in a controlled stationary position, but having turned, so ending facing a different direction from that at the start of the 'step'.
We do not even have to initiate a turn at the beginning of the step. It is enough just to pass centre of the pelvis to the side of the standing foot as the moving foot passes the standing foot, which we can do by keeping the other hip in line with the standing foot. So say we step with a right moving leg: if we keep the hip of the left (standing) leg in line with the left foot, then as the right foot passes it, we will turn to the left, i.e. towards the standing leg. If we pass the hip of the moving leg over the standing leg as the foot passes, we turn the other way, towards the moving leg.
So the feet coming together then separating allow a turn, just as the hands coming together then separating allow a clap.
This brief passing of the feet to create a turn is the reason for the 'brush' in such steps as the third step for the lady in the Impetus Turn, or the fourth step for both partners in the Twilight Waltz.
What happens to the body during a step? Consider asking someone to stand on the right foot with the left foot behind, and to step forward with the left foot. Normal people will swing the left thigh from behind to in-front, then transfer the weight to the left leg. If a series of steps are taken in this fashion, then this will result in the sequence: leg moves, body moves, leg moves, body moves, etc. This uses a lot of energy, alternately accelerating and decelerating the body for every step. It also looks bad.
In a series of steps in dancing, it is more efficient in energy, and nicer to watch, if the body maintains a steady speed. This is often termed 'body flight'. This is like a bicycle, with the body and the machine moving at a constant forward speed, even though the feet and pedals are going forward and backward and up and down.
So to achieve body flight in taking our step forward with the left foot, the dancer must start the body moving at the beginning of the step. The body must be started moving forward of the standing (right) foot as the left foot starts moving from behind to pass level with the standing foot. Then as the left foot continues to move forward of the standing foot, the body continues moving forward so that at the end of the step the body is exactly over the new standing (left) foot. Those with an arithmetic facility will understand that the implication of this is that, on average, the foot moves at twice the speed of the body during the step.
This movement is difficult. During the the step, the body is not balanced. The weight of the body is ahead of the foot on which it is standing. We met a similar problem earlier, in creating a turn by passing the centre of mass of the body to the side of the standing foot during a step. How can these be achieved without falling over? The answer is that falling is avoided by brute strength: by muscle control in the standing leg, holding the weight of the whole body back enough to stop it falling while letting it move forward to progress in the step. This can only be done if the the standing leg is partly bent at the ankle, knee, and hip before the step is taken.
THE WRONG LEG
Normal people, if asked to do a step, will think about the moving leg, the leg onto which they are about to step. But this is the wrong leg to think about when stepping for dancing. The holding of the unbalanced body from falling is accomplished by use of the muscles around the hip, knee, and ankle of the standing leg. Normal people will step from a straight standing leg. Dancers know that as a preliminary to any step, the hip, knee, and ankle of the standing leg must first flex, resulting in a leg that is compressed. If a dancer is stepping to the beat of music, this compression and subsequent extension must occur just before each beat of the music so that the resulting footfall occurs on a required beat. This anticipation of the beat is also not normal, and dancers need time and practice to develop this.
Having compressed the knee of the standing leg before moving the other leg, during the first half of the step, the muscles can be used to project the body slightly upward as the step starts and the body is off balance. This projection upward can be arranged to exactly counter the falling due to gravity of the off-balance body. During the last half of the step, the thigh of the standing leg is pushed back, and the knee is extended, so that at the end of the step, the knee of the standing leg, now at the back, is nearly straight. Simultaneously the ankle of the standing leg is pointed as the step progresses, so that at the end of the step, the back foot is nearly vertical. It is the simultaneous use of the muscles in the hip, knee and ankle of the standing leg during the step that allows a dancer to avoid falling while off-balance.
Advanced dancers also use appropriate twists and tilts of the pelvis in controlling the swing of the moving leg, and in the propulsion from the standing leg.
THE WRONG HIP
Initiating a turn in dancing can accomplished by moving with CBM (Contrary Body Movement) and in CBMP (Contrary Body Movement Position). These ideas are well described in Ballroom textbooks. Curiously there is no use in Ballroom textbooks of their opposites, which might have abbreviations like PBM (Pro Body Movement) and PBMP (Pro Body Movement Position). Nevertheless, all these four methods of taking a step are important in various figures in dancing.
Consider a forward step being taken with the right leg that is the first step of a figure that turns to the right. The dancer can initiate the turn as the right leg starts moving by starting to turn the body to the right in the hip joint of the standing leg. We are turning right in the left hip as we move the right leg. This counterintuitive move can be thought of as turning in the wrong hip. It results in the left side of the body leading the movement even though it is the right leg that is moving. This is Contrary Body Movement.
A more exaggerated form of this initiation of a turn can be achieved by stepping the right foot diagonally to the left, to land either in front of or even across the left foot. The resulting step is described as having been taken in Contrary Body Movement Position.
Considering a forward step being taken with the left leg that is the first step of a figure that turns to the right, one can initiate the turn by again turning right in the wrong hip joint, the hip of the standing right leg. This results in the left side of the body leading the turn as the step with the left foot is taken. This could be described as stepping with Pro Body Movement. Stepping diagonally to the right with the left foot while turning the body to the right in the right hip may be termed stepping in Pro Body Movement Position.
The examples chosen here were for turning right while stepping forward. Corresponding movements can be used when turning left, and/or stepping backward.
THE WRONG KNEE
Many dancers seem confused about when to compress. They step onto a bent leg instead stepping from a bent leg. They are bending the wrong knee, the knee of the moving leg, instead of the knee of the standing leg. For example, stepping onto a bent left leg when stepping sideways to the left results in a lean to the left. To me this gives the impression that the dancer is diving into the step. It looks weak because the leg that is being stepped onto appears to collapse a little. Stepping onto a bent leg only looks strong if there was compression in the standing leg preceding it. This is the case in the Tango and the Samba, where whole figures are danced with compressed legs, but with the body at a constant height from the ground. It is the body dropping as a step is taken that looks weak. In all other dances, the body should always be higher at the end of a step than it was at the beginning. Compression then occurs before taking the next step.
Taking more than one step backwards is not normal. There is a popular perception that in Ballroom Dancing, ladies dance backwards and men forwards. However this is not true because of all the turning. Both need to be able to step backwards confidently when the figure they are doing requires it. This is hard because there are three major problems with going backwards.
The first is that our eyes are facing forwards, so that we cannot see where we are going when stepping backwards. One of my coaches used to say that dancers need to develop virtual eyes in the back of their heads, using all their senses to know what is behind them at all times. In Ballroom Dancing, we also have a partner who is usually going forwards when we go backwards. So, when it is one's turn to travel backward, one must have confidence in one's partner, that one is going to be steered clear of obstacles, corners, and other dancers.
The second problem is we are not used to going backwards. It takes time to develop this continuous knowledge of what is behind you. In Ballroom Dancing, it takes time to develop confidence in the steering of your partner.
The third problem is that our legs are not really built for going backwards. Most people can flex their thigh at the hip forward by 90 degrees or more. However few people can bend the thigh back more than about 20 degrees. This raises problems in Ballroom Dancing.
Having considered steps forward and backward, we may also analyse ways of taking a side step. To do this, we need to distinguish the clinical terms 'abduction' for moving a body part away from the body, and 'adduction' for moving it toward the body,
Ask a normal person to start with feet together and then step to the left, and the person will articulate at the left hip, abducting the left thigh to the side, and put the left foot down, then transfer the weight to the left foot so adducting the left thigh and abducting the right thigh, then finally they will adduct the right thigh at the right hip to close the feet. So a series of steps to the left will go: left leg moves, body moves, right leg moves, etc. Again this is inefficient and looks bad. There are better ways of stepping sideways.
A different way of taking a left step to the side, starting with feet together, is again to use the wrong hip. In this case one may articulate the right hip and abduct the right thigh, so transfering the whole body, including the left leg, to the left. This may be done in two simple ways: either keeping the torso vertical, or else keeping the standing leg vertical.
If the torso is kept vertical, and the standing leg allowed to tilt to the left, this is the lateral equivalent of the forward step described above. The whole body is off balance to the left during the step, and falling can only be avoided by starting with a compressed right leg, and extending it as the step is taken. But the result is that a series of lateral steps, as in the beginning of the Gypsy Tap, may be taken with continuous body flight.
If the standing leg is kept vertical, then the rest of the body, including the torso and the left leg, tilt to the right. Tilting the body to the right of the standing leg while starting to travel to the left would look very ungainly, so the plan is to let the standing leg tilt a little to the left and let the body tilt a little to the right during the side step, so that the body moves to the left but tilts slightly to the right. The idea is to do this as the compressed standing leg is extended. The result of this is a delightful effect called sway. This is of limited value in a continuous set of side steps, as the torso will keep alternately tilting then going upright, and this would look very ungainly. Sway is of value when the following step is in a different direction: either forward or back, usually when the side step is part of a turn. For example, if sway is employed in a continuous set of Waltz turns such as in the Viennese Waltz, the alternation of sway to the right and then left as the body performs each 1/2 a turn between each side step, results in an optical illusion: of the bodies turning continuously about an axis that is inclined back against the direction of travel, rather than rotating about a vertical axis.
Besides being the name of one the the Jive family of dances, this term is also applied to a particular use of the hips when stepping forward and backward. We have already seen how a sideways tilt of the pelvis in the standing hip causes sway, and a twist of the pelvis in the standing hip causes CBM and PCM, all of which are useful in turns. A forward and backward tilt of the hips is useful in stepping forward and backward. The distance that the standing foot maybe be left behind the body when stepping forward can be increased by tilting the pelvis backward from the waist during the second half of a forward step, after the moving foot has passed the standing leg, or in the whole step if stepping from a closed feet position. Conversely, in the first half of a forward step, if the pelvis has already been tilted back in the preceding movement, untilting it, from backward to neutral under the body, during the first half of the step, results in a more powerful movement. This untilting and tilting of the pelvis during each step can optionally be separated from the movement of the torso, leaving the upper body vertical at all times. Alternatively, the whole rest of the body including the torso can be swung forward or back as the pelvis is untilted and tilted. This swinging of the whole body adds the momentum of the torso to a step, and aids in maintaining balance and body flight during a series of steps, although if done too much looks really weird. It must only be done to the extent that the body still starts moving forward at the start of the step despite it being tilted slightly backward. This requires skillful coordination. I didn't say it was easy.
(updated 21 May 2012)