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Paul Glazier: I'm a sports scientist at UWIC and my specialist area is biomechanics, specifically cricket biomechanics.

I provide sports science support for Cardiff and Glamorgan UCCE (University Centre of Cricketing Excellence). I also provide support for The Welsh Cricket Board and Glamorgan County Cricket Academy at Sophia Gardens.

RYG: What is biomechanics?

PG: Sports biomechanics is the science of technique. It applies mechanical principles to help explain sporting performance.

There are two main measurement methods in biomechanics. Vicon is an automated motion capture system that generates kinematic data (displacements, velocities and accelerations) in real-time.

This system is able to measure the distance moved by the limbs and the torso, calculate how fast they are moving, and how rapidly they can accelerate.

The Vicon system works by attaching reflective markers to the surface of the skin at pre-defined locations relative to anatomical landmarks (e.g knees and elbows). The markers are tracked by cameras that are strategically placed around the area of performance.

These cameras have infrared strobes attached to them which flicker at different frequencies so even the fastest movements can be tracked. All data is then sent back to a central computer where a rendered image of the performer and other performance-related data are generated.

Kistler force platforms are devices that measure ground reaction forces. They are typically mounted in the floor so that performers can run over and jump on them. A force platform contains four transducers, one in either corner, so that forces can be measured in the forward-backward, left-right and up-down directions.

These devices are different to pressure platforms that measure force per unit area. They are useful when identifying techniques that might predispose to injury.

RYG: How has biomechanics been used to help the sport of cricket evolve?

PG: Biomechanics has two main aims - to improve performance and reduce injury. The biomechanics of fast bowling techniques has found that technique is related to lower back injuries. In the late 80s and early 90s, lots of fast-bowlers in Australia were getting stress fractures in their lower back.

Biomechanics showed that, during delivery, a counter-rotation of the shoulders was related to lower back injuries. This information has been incorporated into coaching programmes and has reduced the rate of serious injuries in cricket.

As a consequence of these findings three fast bowling techniques have been devised. There's the side-on technique, where the bowler is side-on to the batsman during delivery, the front-on technique, where the bowler is square-on to the batsman and the semi front-on technique, which is halfway between the two.

I've used that research in the work that I've done with Glamorgan County Cricket Academy. I conducted a screening process using fast bowlers to see how much their shoulders counter-rotated during delivery.

Any action with a counter-rotation over 20 degrees could be viewed as being predisposed to future injury. That's something we then work on with the bowlers.

RYG: How has biomechanics helped bowlers enhance their performance?

PG: In terms of performance, the legality of bowling actions is an area that biomechanics has influenced. The regulations are that if the bowling elbow extends by more than 15 degrees, its deemed to be an illegal bowling action, or a throw.

Biomechanics has helped determine an acceptable level of extension. A number of bowlers that have been accused of throwing have done work with biomechanics experts to revise their bowling actions.

RYG: Have you done any research that has helped the game of cricket progress?

PG: At the moment I'm looking at how fast bowlers coordinate and control their bowling techniques. Is there one bowling technique that should be coached or are there a couple of techniques that should be taught?

Maybe we need to look at everybody's bowling technique and help them develop their own style, rather than just blueprinting techniques. I think we should be trying to get away from the one size fits all prescription.

I'm looking at how individual bowlers get the job done in terms of their ball release speed. The other side of fast bowling is accuracy. How do they control their actions from delivery to delivery?

Are we looking at a very stereotypical type of technique with minimal variability or are we looking at a functional-compensatory variability to enable them to get to a fairly consistent release point? High level sports performers have a certain amount of compensatory variability within their technique.

RYG: What is compensatory variability?

PG: A good example of a sport where compensatory variability exists would be pistol shooting. If you look at a highly skilled marksman you find that they're able to keep the barrel of the gun very still.

That's not done by freezing up or locking out the joints in the arm (shoulder, elbow and wrist) - its about a co-variation of the joints. If one of the joints introduces an error into the pistol shooting system the other joints compensate for the action of that joint.

Marksmen aren't robots. Although they're trying to keep the gun as still as possible it can't be kept perfectly still - that's impossible to do. They're pointing at the target and the shoulder, elbow and wrist joints are compensating one another to maintain the position of the barrel of the gun.

There's always a certain amount of variability in any technique. Old ways of looking at that variability used to interpret it as an error in technique. Now that's changed so we're looking at variability as more of a functional thing - as adaptability and flexibility which enables outcome consistency. You can produce the same outcome (i.e. hitting the bullseye on a dart board) by an infinite number of different ways.