Most people, particularly younger players, often struggle with their long passing and shooting when going for power.
The most common cause for this problem is the fact that most people try to tense up and/or "kick" the ball. Both of these actions are very counter productive to not only power, but even worse accuracy.
The correct form for a kick, would be for good swing technique, done with reasonable to little effort. The leg should swing through the ball, and also be accelerating through the ball towards the target, and the whole body should be involved in the action for either balance or co-ordination.
Now I will try to explain this.
The reason little effort should be applied is due to the fact that effort causes tensing of muscles. To someone who does not know better, this may seem good, and that it will generate more power. Well actually it doesn't.
Your muscles work in antagonistic pairs. This means that one muscle is responsible for flexion, and the paired muscle, normally on the other side of the joint is responsible for the extension.
For example, the Bicep and Tricep are antagonistic. That means they work against each other. When you want to bend your elbow (flexion), your tricep relaxes, and your bicep contracts. The opposite occurs when you want to straighten your elbow (extension). This takes reasonable co-ordination when done repeatedly at speed. This is why you benefit from practising technique over and over again, you are actually improving muscle motor neuron co-ordination, but that is a different more complex topic for another time.
So we have established that our joints work antagonistically, but why does that mean that tensing is bad? Well the answer is, when you tense your arm, your bicep and tricep are both contracting together, exerting an equal force, which means your elbow neither extends or flexes, but your muscles grow in size as they contract "fighting" each other. This is why you might often hear people who do weights talking about how training their triceps will make their biceps, and their arm as a whole look much bigger. This is because you can only tense with as much force as your weakest muscle of the antagonistic pair.
So what happens when you tense as you shoot, is that your quadriceps are trying to drive your leg through the ball and apply a force to it. For maximum force and acceleration, your hamstring should be relaxed for this, but if you tense up as you swing, your hamstring is slightly contracting, which in turn puts stress on your quadriceps increasing the risk of injury over time, but more importantly cancels out some of the force your quadriceps are generating. This results in a weaker kick. It also reduces the co-ordination of your swing, resulting in less accuracy.
This is why in golf, a sport which is arguably one of the most technically demanding in the world, the key to a good swing is using little effort to ensure good power, whilst maintaining good accuracy for a perfect stroke.
Now comes point two, and I am going to attempt to explain the physics at work.
Which situation do you think will generate a more powerful kick?
1. The players leg is travelling at 20 metres per second at the time of contact, and continues at constant speed through contact.
2. The players leg is travelling at 25 metres per second at the time of contact, but is decelerating through contact.
3. The players leg is travelling at 15 metres per second at the time of contact, but continues to accelerate through the contact.
Think the answer is obvious? Not to sure? Have absolutely no idea? Highlight below for answer.
The most powerful kick is actually number 3. with number 1 been the second most powerful and number 2 been the weakest of the 3 shots.
This is due to the fact that when you are in contact with a football, its shape is not the same throughout. When you hit a ball, it compresses for an extremely short period of time, before extending and leaving your foot. You may see this if you see a player kick a ball in super slow motion.
During this time of compression, your foot is applying a force to the ball for a specific time.
Force X Time = Change in Momentum.
You may ask what is this? Well momentum is the product of an objects Mass, multiplied by its Velocity. Because the mass of a football doesn't change during a kick (unless you hit it so hard it bursts, or approach the speed of light), that means all of that change in momentum is an increase in the balls velocity.
This is useful, because we know that our muscles can only deliver a set force depending on our strength which comes from training. So to get the biggest ball velocity, we want to have the longest possible contact time of that force.
When you decelerate through the strike, you reduce the contact time. When you maintain speed through the contact, you get average contact time, when you accelerate through the ball however, you massively increase the contact time. This means that you are applying your maximum muscle force, for a longer period of time. This in turn means that your change in momentum on the ball is greater, because your Force X TIME is greater.
This is why it is important to not "kick" the ball but swing through it, and accelerate through it. When you "kick" the ball, you unconsciously slow down during contact. This is why those trained in martial arts do not punch an object, they accelerate through it or aim to hit something half a metre behind the target.
That is why it is so important to accelerate through the ball. Your foot should actually be travelling its fastest after the ball has left your foot. This is why the follow through of a kick is so important, and how it not only affects accuracy, but power when executed properly with acceleration through the ball.
You can tell how good a golfer is by listening to the sound of his swing. If the "whooshing" noise comes just after contact with the ball, then they more than likely have had professional golfing lessons, or are professional themselves. Indeed, accelerating through the ball is a concept which can improve your game in any sport such as AF, Tennis, Football, Golf or even badminton.