网球基础专题
[img]http://sports.people.com.cn/mediafile/200709/10/F200709100732322972667532.jpg[/img]A tennis training program has to meet the demands of an all-round physically challenging, individual sport.
For a tennis player to perform at their best, they must have just the right mix of aerobic and anaerobic endurance, explosive strength and power, speed off the mark and agility. In fact, the amount of strength, speed, agility and flexibility conditioning a player is prepared to undertake has been linked to the standard they play at (1).
A tennis match is characterized by repeated bouts of high-intensity activity. However, a typical rally may last about 6 seconds (2) and not much more than 10 seconds even on a clay court. Between points there is the luxury of up to 25 seconds rest - 90 seconds if it's a changeover. Hence, the overall physical demand is closer to prolonged moderate-intensity exercise (such as distance running) than a true multisprint sport (such as soccer) (3).
A tennis training program must be based on solid aerobic endurance to sustain a high work rate for the duration of a game that may last several hours. Anaerobic endurance is also an essential component so that power over each rally, and in each shot within a rally can be maintained to same high level.
On average a tennis player will move just 3 meters per shot and 8-12 meters during a point (5). It becomes obvious that good speed and quickness around the court is essential in order to reach the majority of these shots. During a match 48% of a players movement is sideways (6) so agility, or the ability to change direction rapidly and under control becomes equally as important.
Finally, a balanced tennis training program should help to prevent injury and over training. For example, a preventative program of wrist extensor strengthening and stretching exercises can help to prevent tennis elbow (7). Specific exercises can also be prescribed to reduce the risk of rotator cuff damage.
Take a look through the articles below as we uncover some of the key principles involved in the complete tennis training approach...
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[[i] 本帖最后由 bing2008 于 2008-4-14 07:55 PM 编辑 [/i]]
Tennis Training Aids
The Racket Bracket® A Breakthrough In Tennis Training AidsThe Racket Bracket® is a breakthrough in tennis training aids because it creates instant results. To explain how The Racket Bracket® works one must first understand why it is so difficult to achieve accuracy hitting a tennis ball with a tennis racket. The main reason is the way our brains use our wrists. The wrist was built to make highly variable adjustments when handling objects like a fork or for power to throw a rock. When a tennis ball approaches a first time player, their natural response is to use their wrist to hit the ball at whatever height it arrives. Why should they adjust their feet when the wrist is perfectly suited to make contact with the ball at almost any height and with considerable power? The problem is that the player then has an infinite number of contact points to choose from when using the wrist and none can be optimized for accuracy and consistency. It would be like going to the driving range to learn how to hit a golf ball except that you would tee the ball at a different position and height every swing. If that were the case you would never get better at golf. The same principle applies to tennis. The goal is to approach the ball the same way each time and hit at a consistent contact point. This is inherently difficult as long as the brain can use the wrist to make the adjustments for you. By blocking the wrist, the brain automatically focuses on positioning the body first which trains the brain to use the feet to make adjustments and for power. With the wrist blocked, your practice time becomes dedicated to positioning and finding the optimal contact point every time you hit the ball. Once that technique and response is ingrained into mental memory you will never think about how to hit the ball again and naturally position yourself better. Check out the testimonials and before/after videos to see why The Racket Bracket™ is the most effective of all tennis training aids.
The Racket Bracket works by simply blocking all the incorrect wrist movements during a swing. As illustrated in this video clip: View how it blocks incorrect wrist movements
[img]http://www.tennisracketbracket.com/tennis_training_aids_forehand_volley.jpg[/img]
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The butt end of the racket can only move a certain number of degrees within the bracket opening that is attached to the wrist. The wrist is blocked, via gripping the racket handle, from being able to break left and right but is allowed to break from a 90 degree to 130 degree angle from the arm (shown by the red line). This angle range is needed to execute the correct swing. This angle can be observed in the photos shown below:
[img]http://www.tennisracketbracket.com/tennis_training_aids_Henman_BackVolley.jpg[/img]
Tim Henman backhand volley
You can see how Tim Henman has great wrist control on his backhand volley. You can see how he moves forward from behind the service line, makes contact with a firm wrist and moves through the contact point without breaking the wrist.
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[img]http://www.tennisracketbracket.com/tennis_training_aids_Nalbandian_Forehand2.JPG[/img]
David Nalbandian Forehand
This is a classical example of preserving the correct wrist control through a forehand. See how David keeps his wrist angle fixed and moves his body through the contact point. He pronates the arm and wrist at contact (windshield washer) to give heavy topspin but the wrist never breaks. On the forehand, some players will break the wrist forward after contact but that is an added feature for advanced players who already have mastered the wrist control up to the contact point.
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[img]http://www.tennisracketbracket.com/tennis_training_aids_DentBackSlice.jpg[/img]
Dent Backhand Slice
Taylor is known for his powerful backhand slice but notice he achieves all that power and consistency without ever breaking the wrist.
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Geeky physics explanation
Work = Force x Distance
In the basic work equation if you increase the force you must decrease the distance in order to preserve the same amount of work or energy. Assuming that it takes the same amount of work to swing a tennis racket in the proper or improper technique a similar equation can be formulated.
Total Swing Work = Leg Work + Hip Work + Arm Work + Wrist Work
The swing complication lies in the way the total swing work is distributed across the four different contributors. Since it is much more difficult to discipline the body to coordinate the work from the leg through the hips, arm and wrist the natural tendency is to limit the work from the legs and hips and increase the amount of work from the arm and wrist to achieve the total swing energy. The problem with using the arm and wrist as the main power supply to the swing is that it is difficult to control or standardize that swing because the wrist has many degrees of freedom that it can move in. Therefore, this type of swing does not satisfy the accuracy and consistency that is needed to achieve higher levels of competitive tennis.
Unfortunately, the incorrect type of swing does not involve a lot of preparation or positioning and therefore becomes the default swing for all beginners. So instructors are faced with a fundamental challenge of changing the natural swing tendency of a player.
The proper swing involves a kinetic chain of events to occur starting with the proper planting of the feet and legs then activating the hips and swinging the arm while minimizing the work from the wrist. This swing takes a lot more thought and preparation and is therefore not the default type of swing for beginner tennis players. Explaining the proper swing technique is difficult because the players mind and body want to hit the ball using the easier improper technique. It is difficult to ingrain the proper swing because an instructor must hit thousands of balls with a student and correct them every time the proper swing is not executed.
The Racket Bracket® teaches a player the proper swing technique by simply removing the player’s ability to use the wrist as a power supply to the swing. Once the wrist is eliminated as a source of power the student magically starts to look for that power from the legs and hips. They must also use footwork to prepare themselves for the shot because without the ability to adjust the wrist they must strike the ball at the same contact point each time. Repeatedly hitting with the device builds in the muscle memory of the swing and ingrains it as the primary way to approach hitting a tennis ball. This is the foundation for any player to build a better tennis game.
The Racket Bracket® simply locks the racket into the same plane as the arm eliminating the ability to flex the wrist in the improper direction. It creates the feel that the tennis racket is just an extension of the arm and not controlled by the wrist. The racket can freely move within the device in the proper manner so that when a proper swing is attained the user will not even notice having the device on. Except for the serve, The Racket Bracket® will strengthen all strokes and volleys regardless of grip type including two handed grips. The Racket Bracket& is also easier to use then all the other tennis training aids.
[[i] 本帖最后由 bing2008 于 2008-3-26 12:55 AM 编辑 [/i]]
How to Grip A Tennis Racket?
The Racket Bracket will ensure the proper contact point and the next question is how to grip a tennis racket. The following diagram on how to grip a tennis racket, shows the different grip formats.[img]http://www.tennisracketbracket.com/how_to_grip_a_tennis_racket.jpg[/img]
[[i] 本帖最后由 bing2008 于 2008-3-26 01:00 AM 编辑 [/i]]
The Forehand Volley
The Forehand Volley[flash]http://www.tennisracketbracket.com/forehand_volley_tip.swf[/flash]The Two Handed Backhand
The Two Handed Backhand[flash]http://www.tennisracketbracket.com/two_handed_backhand_tip.swf[/flash]
The Backhand Slice
The Backhand Slice[flash]http://www.tennisracketbracket.com/backhand_slice_tip.swf[/flash]
The Forehand Groundstroke
The Forehand Groundstroke[flash]http://www.tennisracketbracket.com/Vincent%20Forehand%20Tip.swf[/flash]
The Backhand Volley
The Backhand Volley[flash]http://www.tennisracketbracket.com/Vincent%20Backhand%20Volley%20Tip.swf[/flash]
The One Handed Backhand
The One Handed Backhand[flash]http://www.tennisracketbracket.com/Vincent%20One%20Handed%20Backhand%20Tip.swf[/flash] 打好网球不容易啊
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