Most individuals with incomplete SCI have the potential to recover some degree of mobility and many functional activities of daily living (ADL) through rehabilitation (McKinley et al., 1999). Proper balance control is important not only for mobility and ambulation, but in fact underlies daily home and community-based functional activities in sitting and standing (Huxham et al., 2001).
SCI is accompanied by changes in sensation, loss of muscle strength, decreased cognitive reserve and spasticity amongst a host of other pathological changes that may lead to balance and gait impairments. Balance and gait impairments in turn, may lead to falls. The incidence of falls in people with SCI has been reported to be as high as 75% with loss of balance being the primary perceived factor contributing to falls in incomplete SCI (Brotherton et al., 2006). Moreover, falls are a major contributor of SCI with falls being the most common cause of SCI in individuals > 60 years old (Dohle and Reding, 2011). It is not currently known the extent to which deficits in balance may affect people with SCI.
The central nervous system (CNS) maintains balance by integrating information from visual, vestibular and sensorimotor systems (Horak and Macpherson, 2006). Greater understanding of the principles underlying the neural control of movement and functional recovery following neurological injury has resulted in increased efforts to design rehabilitation strategies based on task-specific training (Wolpaw and Tennisen, 2001; Behrman and Harkema, 2007; Fouad and Telzaff, 2012). This concept has been translated to various rehabilitation interventions, such as those targeting walking outcomes (e.g. body-weight supported treadmill training) (Mehrholz et al., 2008; Van Hedel and Dietz, 2010; Wessels et al., 2010; Harkema et al., 2012) or arm and hand function (e.g. constraint-induced movement therapy) (Taub et al., 1999; Wolf et al., 2002). For balance, task specific rehabilitation similarly focuses on the achievement of the three main functional goals encompassing balance: 1) maintaining an antigravity posture such as sitting and standing, 2) anticipatory postural control during voluntary self-initiated movements and 3) reactive postural control during an unexpected perturbation (Berg, 1989).
There has been a great deal of focus on the effectiveness of gait training in SCI rehabilitation research (Mehrholz et al., 2008; Van Hedel and Dietz, 2010; Wessels et al., 2010; Harkema et al., 2012), but there has been relatively little attention on the impact of interventions specifically targeting balance outcomes. In other neurologic populations, there is some evidence that task-specific balance training can be effective for improving functional outcomes. A systematic review in people with stroke found moderate evidence that balance could be improved with exercises such as challenging static/dynamic balance ability and practice of balance in different functional tasks, including sitting, standing, walking, and stair climbing (Lubetzky-Vilnai and Kartin, 2010). In recent years, and with the rapid development in technology (e.g., exoskeletons, virtual-reality), there has been more data available about balance outcomes following gait training (Dobkin et al., 2006; Wu et al., 2012; Harkema et al., 2012), as well as specific sitting (Boswell-Ruys et al., 2010; Harvey et al., 2011) or standing (Alexeeva et al., 2011) balance interventions in people with SCI.