# Gait Biomechanics for Fall Prevention among Older Adults
## 5 Fall Prevention Strategies
### Footwear Intervention  
Footwear is an essential consideration for fall prevention, with various potential effects on reducing the risk of tripping and slipping. In short, tripping prevention can focus on increasing swing foot clearance (i.e., MFC) by modifying the footwear geometry, while shoe-outsole modifications can provide sufficient friction to minimise slipping. [PERSON] and colleagues [65; 66] investigated the effects of shoes on gait biomechanics and associated falls risks. Their research outcomes were largely in agreement with previous reports about'safe footwear'. A shoe insole is a direct interface for the foot and influences gait control mechanics. [PERSON] and [PERSON] [49] introduced ISEAL technology, which supports ankle dorsiflexion and aversion, especially in the heel. As in Figure 6 (top left), the specific heel geometry combined with texture installation succeeded in increasing MFC and guiding the foot's centre of pressure (COP) to stabilise balance [38]. [PERSON] et al. [67] devised a shoe insole called SoleSensor\(\copyright\), installing tubes peripherally to trigger cutaneous receptors when the foot COP travels toward the BOS boundary and to promote afferent feedback for faster reaction speed to avoid balance loss. Another type of shoe inside consideration is the incorporation of additional cushioning effects to reduce plantar foot pressure. Custom moulding is also common for shoe insole, often utilising 3D foot scanning systems to maximise the contact area between the foot and the shoe insole. Such foot-pressure-redistribution techniques may not directly reduce falls risks but can protect the foot from deformity and pain, possibly helping to sustain dynamic balance. The custom moulding of shoe insole, however, may not always solve foot problems but, rather, could exacerbate the condition. If a foot deformity exists, merely scanning the foot results in moulding the shape of the damaged foot and makes it rather difficult to overcome these problems. Contrary to a shoe-insole intervention to reduce the risk of tripping, slip prevention can be summarised as 'COF greater than RCOF', but attempts to reduce RCOF may not be practical. A lower RCOF can be achieved with smaller horizontal and greater vertical GRF components. Such walking patterns can be characterised by'stomping' but cannot be recommended as everyday gait adaptations due to potential damages to lower limb joints. Shoe modification for slip prevention is, for this reason, almost limited to the outside structure by providing sufficient friction. For slip prevention, the horizontal foot contact force must be smaller than the friction between the two interfaces: the walking surface and shoe outside. The indicator of'slipperiness' and coefficient of friction (COF) is determined mostly by materials and surface conditions (i.e., contamination), but there is no single best outside material for reducing the risk of slipping. Polyurethane (PU) is, for example, slip-resistant, particularly against a contaminated surface compared to other materials, but effects can wear off relatively in a short period of time [68,69]. Thermal plastic rubber (TPR) is generally not slip-resistant; however, TPR can be useful on an icy surface. On a dry surface, natural rubber is the optimal material, but it is questionable whether we need to consider falls from slipping when the surface is not slippery. Softer outside materials generally provide higher COFs but can wear off and lose their slip resistance quicker. Considering the lifespan of footwear, extremely soft outsoles may not be cost-effective. Outside treads can be another consideration, but further research should be undertaken to effectively reduce the risk of slipping [70]. Figure 6: (**Top left**) Texture installation on the insole to guide centre of pressure movement; (**bottom left**) application of electrical muscle stimulation on dorsiflexors; (**right**) foot corrector for dorsiflexors’ training.