There are also different degrees of forwardness.
In the beginning you could say it is the absence of restraint. Unconstraint is the hoses ability to flex and move only as much as required to support itself and rider. It will be from this that all further training will evolve from.
Forwardness is NOT running the horse off its feet.
As a supplement to this topic there was an article in dressage daily about this and problems that occure in its achievement.
Allowing Forward Motion
Allowing Forward Motion Training Tips - Meredith Manor Written by Nancy Wesolek-Sterrett Thursday, 21 January 2010 07:14 As riders struggle to properly apply and coordinate their aids, they must constantly ask and answer a persistent question when the horse does not respond as they intended—is it me or is it my horse? This basic question never goes away, even for the most experienced rider. To answer it, always check your basic position. If your horse is reluctant to move forward, check your ability to follow the motion of the horse's gaits. We use our following seat and leg aids to encourage the horse to move forward. In theory classes, we discuss the six basic riding skills (relaxation, balance, following the horse's motion, applying the aids, coordinating the aids, and influencing the horse) as a sequence.
In the classroom discussions, it may sound as though a rider masters one skill completely at all three gaits before proceeding to the next skill. Theory gets messy, however, when the seat hits the saddle. A rider may master several skill levels quickly at the walk, but be at the first skill level when trotting and a still different skill level at the canter.
How 'forward' a given horse feels on a given day depends not only on the rider's skills but also on the horse's temperament, when he last worked, whether he has any muscle soreness that day, where he is in his own progress up the training tree, etc. Simple things can matter. For example, your ride starts in the stall. If you are hurrying and hustling the horse as you groom and tack up, creating tension before you even reach the arena, your horse will not have a relaxed, forward feel when you finally mount up.
So, even though you applied what you thought were correct aids, there can be many reasons why you did not get free forward motion in the gait, in the direction, at the speed, or with the degree of collection, etc., you wanted. As an instructor, I constantly evaluate whether the rider did something that blocked free forward motion. Here is a checklist of some common ways riders restrict forward motion that can help you evaluate whether it is 'you' or 'the horse':
Blocking with the Seat
Your seat must follow the horse's motion in order to allow the horse to move forward. Following the horse's motion requires rhythmically opening and closing your hip angles as the horse's back moves. If you say 'go' with your leg aids but your seat does not immediately follow the forward swing of the horse's hips as he picks up a hind foot, you restrict forward motion. The degree to which your hip angles open and close will vary depending on the gait, the size of your horse, your horse's athleticism, and other factors. But it is guaranteed that if you cannot follow the horse's motion, your hips will restrict his forward motion in some way.
Sometimes it helps to think of pushing your hips toward your hands as your horse moves to provide that feeling of an opening as the hips follow the horse's motion. Another image that helps some riders is to think of a string attached to their belly button that pulls and releases as the horse's back rises and falls. Riders with tense, braced hip muscles will bounce and many horses respond by slowing down to avoid the impact of this bouncing .
Riders with tense hip muscles cheat at the canter by pumping with their upper body. Too much upper body motion, head and neck motion, flying elbows or flopping legs are all symptoms of tense hips that are not correctly absorbing the horse's motion. Other riders collapse at the belly button to absorb the motion. I ask these riders to envision a 2 X 4 board running through their torso perpendicular to the ground. This helps them get their upper body tall and in rhythm with the horse and once they have the rocking chair motion, we work to transfer the rocking to the pelvis instead of the upper body. The goal is to follow the horse's motion by opening and closing the hips while maintaining a steady, relaxed upper body.
The bigger the horse's canter motion, the more your hip angles must open and close in order to follow this motion. Meredith Manor has a mechanical bull (nicknamed "the bull") which is calibrated to simulate a cantering horse's motion. Riding the bull is like cantering on a 21-hand horse—a horse with a large canter motion. Riding the bull gives students a really exaggerated feel of opening and closing their hip angles. Following a real live horse's motion more closely is much simpler once they have ridden and mastered the bull.
Blocking with the Legs
If you use constant leg pressure to hold your position on the horse, or squeeze and hold with your legs, some horses feel this as a restriction of movement rather than as an encouragement to go forward. Other horses may try to run away from this pressure. Either way, the horse is not moving correctly forward from your leg.
Most beginning riders tend to grip with the knee and thigh. Long-legged beginners tend to turn their toes out and hang on with their calves. Sensitive horses may scoot or run from this annoying pressure while the lazy horse or a horse that has been taught to stop from the leg simply will not go. If you try to enforce these incorrect leg aids with a touch of the whip, the horse may kick out, buck or balk as a way of saying, "Not fair! Mixed message!"
A squeeze and release with the leg or a pulsing leg urge the horse forward rhythmically. A softly supporting leg can steady a flighty horse. A gripping leg always restricts forward movement.
Blocking with the Reins
Beginning riders who use their reins to help them balance often use the leg to ask 'forward' then pull back to keep their balance as the horse begins to move. This is an obvious block—saying 'go' and 'stop' at the same time—that confuses the horse.
Less obvious is the more advanced rider whose hands do not follow or allow the motion of the horse's head at the walk and canter or whose hands are tense or feel 'backwards' to the horse at the trot. This rider's steady but tense hand restricts the horse's head and interferes with his ability to move forward freely in a relaxed manner. The hands do not allow an opening for the horse's forward motion. Depending on the horse's disposition, he may become agitated and try to run from this restriction or he may shut down and ignore the leg aids by not going forward.
Ride as though your hand and arm belonged to the horse, not to you. Do not allow tight fingers, tense forearms or locked elbows to block forward motion. Think of riding with a hand that operates forward rather than backward.
Going back to our basic question—is it the horse or is it the rider—how do we decide in that split second whether to enforce our aids or not? When we teach horses new things, we first figure out a way to show them what we want. When they understand what we are showing them, then we can ask them to do it. When we are sure they completely understand what we are asking, we can tell them to do it. Only when we are absolutely sure the horse completely understands the question can we enforce with an artificial aid like the whip without confusing him.
So when that basic question comes up, ask yourself how far along you are in mastering the six riding skill levels. Until you reach the level of being able to influence a horse consistently, the default answer to the question is generally that the communication breakdown is on the rider's side, not the horse's side. Even then, the question never completely goes away. This is just one of the things that makes riding a lifelong learning process.