INJURY PREVENTION

Figure 3: The ‘foot up’ or pinpoint serve used by Lleyton Hewitt

ingly, the centre of mass travelled at a greater angle in the pinpoint serve than the platform serve. This means that plat- form servers will land further inside the court playing area, which would be a real advantage to a player employing serve- volley tactics in which he needs to move towards the net as much as possible before the ball is returned. A pinpoint style of serving would be the preferred method for a baseliner who needs to stay near the back of the court. So the biome- chanical style employed to deliver a serve has a strong link to the tactical style used by a player, and even to the type of surface on which he is playing.

CHANGING TECHNIQUE AND INJURY PREVENTION: Modern tennis strokes are continually evolving in response to the players’ search for the winning formula, and as equip- ment technology changes, this makes sub- jective analysis by the coach difficult, especially if he does not have a basic understanding of biomechanics. With established techniques, good coaches should be able to analyse their players at the ‘faulty movement’ stage. This, after all, is what coaching is principally about,

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Figure 4: The ‘foot-back’ of platform serve used by Pete Sampras

analysis and skill acquisition, and enhancement of correct technique. If they can go back one step further and realise that faulty joint alignment is the root cause, then they too can go to the crux of the problem. But it is probably at this stage that physiotherapists, with well- honed powers of observation, can easily pick up the hyper-extended knee, the hyper-lordotic spine or protracted scapu- la. Faulty position leads to faulty move- ment, which is much harder to detect and analyse, especially when the end result - a 140 mph serve or crushing forehand winner - is clearly effective!

Kinematic analysis can be carried out by coaches simply using subjective observa- tional analysis. However for more detailed objective analysis video or 3-D techniques should be used. Video analysis is a useful tool but does have some limitations. Most commercial systems record movement at 25 frames per second which can be too slow for many fast movements and thus detail maybe lost. Video analysis also tends to be planar ie. movement can nor- mally only be analysed for the side or the front at any one time, although this does provide information on joint and segment

movements in those planes no informa- tion on rotation can be determined. For quantitative analysis of joint and segment movements in all planes 3-D analysis sys- tems are used. Such 3-D systems provide excellent data on the movement in all planes, however, for many coaches and players there are also limitations in that the equipment is expensive and appropri- ate expertise in data analysis and inter- pretation is required.

Technique that is biomechanically incor- rect will always carry injury potential in the long term. Identifying the problem early in an athlete’s career, preferably before they reach elite status, gives them time to make the necessary technical adjustments without affecting their per- formance and ranking too much. Once in that ‘elite’ category, long term injuries, rehabilitation, and changes in technique can be a major factor in reducing the ranking, and therefore also the earning capacity, of the performer. The modern and well-informed performance coach will increasingly turn to biomechanical analy- sis as a valuable tool in injury prevention, and as the basis for highly specific train- ing and assessment of players. There is

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