I hesitate to question Kevin Brereton's statements on technique, but it seems to me that there are two different aspects to be considered with respect to the usefulness or otherwise of "body movement" if we define it as movement of body parts other than the arms during a croquet swing. If power is the main consideration (which it rarely is in croquet) then it should start from the larger muscles in the trunk and/or legs as Kevin suggests. If accuracy rather than power is the main aim, then the fewer muscles involved and needing to be co-ordinated the better. Try the following experiment:
Make a dot with a pencil on a sheet of paper lying on your desktop.
Try to place the pencil point again on the exact same dot by : moving your whole arm from the shoulder without any part of it resting on the desktop and resting your hand on the desktop so that only the muscles in the end of your fingers are involved.
You will find that (2) allows greater accuracy, as fewer muscles are involved. People who play darts or lawn bowls or snooker will be aware of this principle that you should use as few muscles as possible for accurate co-ordination.
In cricket or tennis, where power is often important, the trunk muscles and leg muscles come into play in allowing power to be generated with the apparent effortless ease exhibited by the top players; but it requires a degree of co-ordination that not many of us possess naturally or are capable of developing. Even in these sports, a delicate stop-shot in tennis, or a fine cut or leg glance in cricket should be played using only the arms and/or wrists, and avoiding body movement.
I believe we have much more to learn on the subject, and have spent time working with a bio-mechanics expert using force-platforms, electrodes attached to muscles and linked to computers, impact measuring devices, etc. The results so far have been inconclusive for reasons connected partly with the nature of biomechanics experimentation, partly with the personal interests of the expert, and partly with croquet politics. I can explain further if anyone is interested (which is unlikely), or is thinking of pursuing such research themselves (possible, but probably ill-advised).
A further point from Kevin's letter is that the centre of gravity of the player will usually move during a swing. This may not matter provided it remains above the base on which he is standing. Thus a step-stance rather than a level stance is recommended, especially for players with small feet (seriously!) and less body weight, and for everyone when playing strokes such as long rushes, rolls and cannons where real power is required. It may be of comfort to some to realise that additional body weight, particularly around the nether regions, is an advantage for the sport of croquet because it provides more stability and can be used to counterbalance the forward movement of the arms.
The alternative to adopting a stance which can cope with a forward movement in the centre of gravity without overbalancing is to either move the base forward during the swing by walking as some players do, or counterbalance the forward movement of the arms by moving some body part of similar mass in the opposite direction. Which body part should you consciously move backward during the swing? David Maugham and Paul Skinley are two who seem to noticeably use the top part of the trunk as a counterweight, but most top players tend to minimise body movement and contrive to keep the centre of gravity above the base provided by their stance. It can be easier to do this if you start with the weight back on your heels, allowing a considerable degree of forward movement of the arms and mallet before any counterbalancing backward movement is needed to keep the system stable. John Riches of Enfield, Australia John.Riches@adelaide.on.net