The Lag

The Common Core of modern power tennis is the lag. The lag is how the body harvests energy produced by the lower body and converts it into power in the long strokes - the groundstrokes, serve, and overhead. It can result in astounding pace with precise control if performed correctly. The last part is a little tricky since the lag, while absurdly simple to execute, is not something that one will stumble upon. It is a highly unnatural way of addressing the ball and is counterintuitive. If you are an advanced player you may find that you are already doing it on one or more of your strokes - usually your hardest and best one - but you may not have applied the technique more generally.

The lag occurs between the load and explode phases of the lock, load and explode. The forces that will inject spin and directional control into the ball have been tucked away in the muscles of the forearm during the load phase, and now it is time to add some pace to the ball. During the load phase, the forward rotation of the shoulders opposed by the inertia of the racket head tends to flip the racket so that the racket head lags behind the hand/wrist unit. As the shoulders continue to rotate, the wrist drags the racket forward, accelerating it and building up racket head speed. Since the wrist and racket are accelerating, the racket is trapped in the lag position by its inertia. The control and spin forces stored in the forearm muscles are trying to escape and release the racket from this prison, but they cannot overcome the inertia of the racket head which can be upwards of 15 pounds. Thus the lag has two important functions; allow time to build racket head speed for pace, and keep the stored control and spin forces bottled up while it does so.

Blasting into Orbit

As the racket accelerates, one's tendency is to want to catch the racket head up with wrist - to "bring the racket head around" and push it at the ball. This direct approach never works. Like so many things that make intuitive sense in tennis, spanking the ball on its behind is just wrong.

Instead, your goal should always be to hit across the ball. Since our limbs comprise a collection of rotating joints and levers, the geometry of a stroke naturally resolves itself into a series of expanding elliptical curves or orbits.

There are no natural straight lines in a stroke. Instead, you should envision the path of the racket as a collection of graceful orbits, each with a different center and diameter. Usually, the center is a joint and the diameter is the length of a limb or collection of limbs. What you should feel during the lag phase is pulling the racket butt-first towards the ball, and at the last possible moment, the racket face snaps around into the ball (see video left). If this sounds familiar, it is because it is exactly what happens in the pro serve. The real key to the lag is aiming the heel of the racket, not the face, at the ball. Leverage comes from two sources. First, expanding the size of the orbit is an attempt to match the resistance of the racket head's moment of inertia to the pulling power of the shoulder as the racket accelerates. Second, by pulling rather than pushing the racket head, you are not directly fighting the racket head's moment of inertia. Think of pushing a hammer's head into a nail versus pulling the handle. The farther a weight is from a torque trying to rotate it, the more resistance to the torque. When pulling, the moment of inertia becomes irrelevant. You can get the racket head moving by pulling it then let its momentum carry it around into the ball without having to push it. You must not try to drive the racket head around into the ball; rather you should get the racket head moving and then let it find its way to the ball, like sending a missile into orbit and then letting gravity take over. The lag starts violently and ends passively; I call this letting the racket do the work, and it is key to allowing the racket head to explode into the ball, injecting stored control and spin forces held in place during the lag phase.