Fit – the starting point for all footwear
The essentials of good shoemaking last and upper design for tennis shoes are that they should:
Ensure that the heel is firmly held in the backpart (the fastening system also plays a part in this)
Support, but not restrict, extreme angles of ankle flexion
Secure the forefoot by holding firmly around the joint of the foot (across the first to fifth metatarsal head). The position of the joint of the foot should coincide with the flex line of the shoe
Provide adequate space for all five toes in terms of both length and width.
Tennis is a multi-directional sport – unlike running – with rapid skipping and vigorous lunging movements in all directions. This means that there are high forces tending to cause the foot to slide backwards and forwards, and side to side inside the shoe if the fit is not secure. Even with a secure fit, the foot will be buffeted against the upper, hence the need for toe space.
Socks (hose) play a particularly key role in tennis shoe comfort. They absorb sweat, provide cushioning and reduce rubbing, thus lowering the likelihood of blistering occurring. Individual players can effectively customise the fit of their shoes by selecting hose of the right thickness for them. Asymmetric socks (designed specifically for left and right feet) eliminate surplus material from in front of the lesser toes without the wearer having to pull the hose on too tightly.
A long fastening system, usually laces, from the instep down to the joint again allows wearers to customise the fit to their foot shape. It also permits adjustment during the game – feet swell as they get hot and spread under the repeated heavy pounding.
Sole grip dependent on surface
Tennis is played on a wide range of surfaces, both hard and resilient, and with varying levels of friction. The nature of the surface influences the players’ technique and movement. For example, the clay court is unique in requiring a completely different style of play to that on hard courts, as the player frequently makes a controlled slide to execute a shot.
Consequently, there are different types of tread patterns marketed for different surfaces – smooth soles for play on indoor carpet, pimpled tread for grass and artificial grass courts, and shallow intricate tread patterns for hard and clay courts. The classic pattern is the shallow zigzag or herringbone pattern, but many other designs are also used. Soles may also incorporate small islands of circular design in the tread to create pivot points where torsional or rotational friction is reduced in order to make twisting easier, thus reducing torsional strains on the lower leg.
Tennis is not usually played in the rain, but court surfaces may be wet after rain or with evening and winter condensation. Many amateur club players may have to contend with ageing and perhaps deteriorating courts, with encroaching moss and algae. This can cause dangerous sudden loss of grip during play, but is really a problem of court maintenance rather than footwear selection, as no shoe sole will prevent slip under such conditions.