Abstract
Background: Obstacle-crossing increases the risk of falls in older people. This study aimed to identify the effects of long-term Tai-Chi Chuan (TCC) practice on the control strategies for obstacle-crossing in older people. Methods: A multi-objective optimal control technique with measured gait data was used to identify the control strategies adopted by 15 long-term TCC practitioners and 15 healthy controls when crossing obstacles of different heights, in terms of the best-compromise weighting sets for the conflicting objectives of minimizing energy expenditure and maximizing the toe-obstacle and heel-obstacle clearances. Results and Conclusions: The long-term TCC older practitioners adopted a best-compromise control strategy similar to those adopted by young adults, with greater weightings on the minimization of the mechanical energy expenditure and smaller weightings on foot-clearance as compared to non-TCC controls (TCC: 0.72, 0.14, 0.14; Control: 0.55, 0.225, 0.225). This strategy enabled the long-term TCC older practitioners to cross obstacles with significantly greater leading-toe clearances but with relatively less mechanical energy expenditure. With the current approach, further simulations of obstacle-crossing mechanics with a given weighting set will be useful for answering clinically relevant what-if questions, such as what abilities would be needed if the non-TCC older people were to cross obstacles using the crossing strategy of the TCC people.
Highlights
More than 25% of older adults reported falling at least once a year, with a higher incidence of falls in frail individuals or those with disabilities (Blake et al, 1988; Tinetti et al, 1988; Tinetti et al, 1994; Graafmans et al, 1996; Bergen et al, 2016)
The long-term Tai-Chi Chuan (TCC) older practitioners were found to adopt a best-compromise control strategy for obstacle-crossing similar to those adopted by young adults, with a greater weighting on the minimization of the mechanical energy expenditure and smaller weightings on foot-clearance as compared to non-TCC controls
The long-term TCC older practitioners were able to adopt a single control strategy for obstacle-crossing of different heights similar to those adopted by young adults (Lu et al, 2012), with greater weightings on the minimization of the mechanical energy expenditure and smaller weightings on foot-clearance as compared to non-TCC controls
Summary
More than 25% of older adults reported falling at least once a year, with a higher incidence of falls in frail individuals or those with disabilities (Blake et al, 1988; Tinetti et al, 1988; Tinetti et al, 1994; Graafmans et al, 1996; Bergen et al, 2016). Previous studies on obstacle-crossing have suggested a need for better strategies for improved balance and end-point control to reduce fall risks in the elderly (Chen et al, 1994; Chou and Draganich, 1998; Draganich and Kuo, 2004; McKenzie and Brown, 2004; Lu et al, 2006). Tai-Chi Chuan (TCC) as a low-speed, low impact exercise is beneficial for retaining or regaining balance for older people (Lai et al, 1995). It remains unclear whether TCC practice would help develop better movement control during obstacle-crossing in the elderly for reduced risk of falls. This study aimed to identify the effects of long-term Tai-Chi Chuan (TCC) practice on the control strategies for obstacle-crossing in older people
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