It has been several decades since it was first demonstrated that daily treadmill training can enhance locomotor activity in animals that have a complete spinal cord transection (Edgerton et al., 1991; Barbeau and Rossingnol, 1987). In this approach, partial body weight support is provided by a harness suspended from the ceiling or a frame while limb stepping movements are assisted by a moving treadmill belt. In the ensuing years, BWSTT strategies have been introduced as a promising approach to improve ambulatory function in people with SCI (Barbeau and Blunt, 1991), raising much excitement and interest among rehabilitation specialists and neuroscientists.
In this review, we focus on the BWSTT intervention studies that report functional ambulation outcome measures (such as walking speed or endurance). These studies tend to focus on individuals with motor-incomplete SCI lesions as the recovery of overground functional ambulation has not been shown in people with clinically complete spinal lesions (Waters et al., 1992). Although modulation of muscle (EMG) activity during body weight support treadmill-assisted stepping in individuals with complete SCI lesions has been shown (Dietz and Muller, 2004; Grasso et al., 2004; Wirz et al., 2001; Dietz et al., 1998; Wernig et al., 1995; Dietz et al., 1995; Faist et al., 1994), there has not been any evidence for functional ambulatory gains in this sub-population.
In people with motor-incomplete SCI, much motor recovery already occurs within the first 2 months post-injury; the rate of further recovery then decelerates over the next 3 to 6 months (Burns and Ditunno, 2001). For the purposes of this review, we defined SCI <12 months post-injury as acute/sub-acute and SCI >12 months post-injury as chronic.