Examining the role of external and internal attention focus instructions during rehabilitative walking training on real-time conscious motor processing by older adults at risk of falling in Hong Kong – a pilot study
Dr Wong, Wai Lung Thomson (Principal investigator)
Attentional focus instruction, Walking training, Conscious motor processing, Older adults, Risk of falling
Psychology,Rehabilitative and Physical Medicine
Block Grant Earmarked for Research (104)
HKU Project Code
Seed Funding Programme for Basic Research
Walking is well acknowledged as the most common fall-related activity although it should be one of the most essential daily activities for community-dwelling older adults (Lai, Low, Wong, Wong & Chan, 2009). It seems to be effortless and requires very low degree of attention (Sparrow, Bradshaw, Lamoureux, & Tirosh, 2002). Older adults are mostly able to perform a wide range of motor skills, including walking, automatically (i.e., with little conscious effort), but may try to use conscious motor processing (i.e., conscious monitor and control of movements) to assure the efficiency of their movements when encountering difficulties or stress. Unfortunately, conscious motor processing utilizes knowledge and strategies that are explicitly processed in the working memory (Baddeley, 1994) that may in return affect the functional performance of older adults in their daily activities. The process of regressing from automatic motor processing to conscious explicit motor processing, especially under stress, has been known as "reinvestment" (Masters, 1992; Masters & Maxwell, 2008). Masters (1992) defined reinvestment as "an inward focus of attention in which an attempt is made to perform the skill by consciously processing explicit knowledge of how it works" (p. 343). The propensity of reinvestment can be measured by the Movement Specific Reinvestment Scale (MSRS – Masters, Eves, and Maxwell, 2005). The scale assesses two separate factors (i) movement self-consciousness and (ii) conscious motor processing (Masters & Maxwell, 2008; Masters et al., 2005) in which higher scores represent a greater propensity for conscious motor processing. Substantial evidence suggests that people who with high willingness to make successful movements or who are self-conscious about the way in which they move display an increased propensity for reinvestment (Masters, Polman, & Hammond, 1993; Fasotti & Kovacs, 1995; Stapleton, Asburn, & Stack, 2001; Grattan, Ghahramanlou, Aronoff, Wozniak, Kittner, & Price, 2001; Orrell, Masters, & Eves, 2002; Masters, Pall, MacMahon, & Eves, 2007; Wong, Masters, Maxwell, & Abernethy, 2008). More importantly, the theory of movement specific reinvestment has been utilized in different disease groups and clinical settings for individuals with movement difficulties or disorders, such as Stroke and Parkinson diseases (Orrell et al., 2002; Masters et al., 2007). It was also found that the longer the duration of movement difficulties associated with the disease (e.g., Parkinson disease) the higher the reinvestment score (Masters et al., 2007). In older population, Wong et al. (2008) was the first attempt to investigate reinvestment propensity in older adults. It was discovered that older previous fallers have a higher propensity to consciously motor processing than age-matched non-fallers. Nevertheless, this conscious control of movements by internal focus of attention may lead to movement disruption, possibly by constraining or interfering with automatic motor control mechanisms (Deikman,1969). This suggests that older adults who have developed an increased propensity to conscious motor processing may exhibit an internalized focus of attention, in which they present with elevated awareness of their own limb movements, which interferes with the awareness of external (environmental) information. Subsequently, Wong, Masters, Maxwell & Abernethy (2009) found that older fallers have higher tendency to divide their attention between the external environment and internal mechanisms of their movements, especially under stress, while older non-fallers focus externally during walking. Efforts to attend both internal and external information by the older fallers may overload resources in the working memory (Baddeley, 1994) which may in return impact negatively on movement control. According to the ‘constrained action hypothesis’ (McNevin, Shea, & Wulf, 2003; Wulf, Shea, & Park, 2001)), an external focus of attention, may conversely allow "the motor system to self-organize more naturally, unconstrained by conscious control" (Wulf et al., 2001). However, it is unclear how external focus and internal focus instructions during rehabilitative walking training specifically affect real-time conscious motor processing propensity of older adults. Various studies have examined the influence of external and internal attention focus instructions during balance tasks learning on stabilometer, ski simulator, Pedalo and compliant surfaces in young adults (McNevin et al., 2003; Wulf, HOs & Prinz, 1998; Wulf & McNevin, 2003; Wulf, Mercer, McNevin & Guadagnoli, 2004; Wulf et al., 2001). Participants were trained with external attention focus instructions generally demonstrated more effective learning in balance tasks than participants trained with internal focus instructions. Moreover, several studies examined the effect of external and internal attention focus instructions on muscle efficiency, measured by electromyography (EMG), during different movements (Vance, Wulf, TOllner, McNevin & Mercer, 2004; Zachry, Wulf, Mercer & Bezodis, 2005; Wulf, Dufek, Lozano & Pettigrew, 2010). The studies showed that external attention focus instructions resulted in better muscle efficiency and performance in basketball free-throw shooting (Zachry et al., 2005) and high jump (Wulf et al., 2010). Walking, especially for older adults with reduced lower limbs muscle strength, requires effective coordination within different muscles so as to perform effectively. Huxhold, Li, Schmiedek, and Lindenberger (2006) suggested that standing while concurrently performing an easy cognitive task with an external focus (watching a random series of digit ranging from one to nine) rather than internal focus can improve the efficacy of postural control of older adults. The authors argued that an external focus of attention allows the motor system to self-organize and thus more efficiently execute movement although a more difficult concurrent cognitive task can deteriorate the postural stability. It was also found that gait pattern and variability were improved when older participants were asked to perform an easy concurrent working memory task than when they walked without a concurrent task (Lovden, Schaefer, Pohlmeyer, & Lindenberger, 2008; Verrel, Lovden, Schellenbach, Schaefer, & Lindenberger, 2009). However, to best of our knowledge, no study has investigated and compared the effect of external and internal attention focus instructions on real-time conscious motor processing (reinvestment). This proposed study will be the first attempt to do so and will be an essential pilot study for future rehabilitative psychomotor training studies of older adults. Objectives: The main objective of this proposed study is to examine the role of external and internal attention focus instructions during walking on real-time conscious motor processing by older adults at risk of falling in Hong Kong. It is hypothesized that: 1,Older adults who display a high propensity for movement specific reinvestment, instructions that direct attention externally to walking movements decrease real-time conscious motor processing (measured by decrease in cognitive loading using functional near-infrared spectroscopy) compared to instructions that direct attention internally; 2, Older adults who display a low propensity for movement specific reinvestment, instructions that direct attention internally to walking movements increase real-time conscious motor processing (measured by increase in cognitive loading using functional near-infrared spectroscopy) compared to instructions that direct attention externally. The results will inform influential practical implications of how to design targeted interventions to ameliorate the propensity for movement specific reinvestment in older adults during rehabilitation.