Non-Body-Weight Supported Training for Standing Balance
Overground walking training does not require expensive devices and more closely resembles natural walking conditions in daily life, and it is likely to achieve a patient’s full engagement, encouraging voluntary movements compared to walking on a treadmill (Yu et al. 2019). Overground training is usually implemented when there is improved neuromuscular capacity and a readiness to learn overground skills to use in the home and community. Though overground training is often used as a control group for other types of treatment (e.g., treadmill training), some studies have assessed a progressive approach to overground training, that is varying intensities, intervals, and/or incorporating perturbations to measure balance.
Discussion
There were seven RCTs, one secondary analysis of an RCT, and four pre-post studies which assessed different non-body-weight supported training interventions on standing balance outcomes that have been carried out in patients with motor incomplete and chronic SCI. These included ABT, community-based ambulation training, task-specific training, impairment-based training, different stepping tasks, overground (locomotor and other exercises) training, overground perturbation training, resistance training for lower extremity muscle groups, aerobic exercise using a recumbent cross-trainer, or the application of visual feedback during different exercises; or training intensities (high vs. moderate).
In a high-quality RCT, Unger et al. (2021) included 20 patients (10 with paraplegia and 10 with tetraplegia) who were randomly allocated to perturbation-based balance training or conventional intensive balance training for one hour, three times per week for eight weeks. After the intervention, and at 3 and 6 months follow-up, reactive stepping ability, balance control (Mini-BESTest and Community Balance and Mobility Scale [CB&M]), balance confidence (ABC scale), fall concern (Falls Efficacy Scale – International [FES-I]), falls parameters (e.g., number of falls, time to first fall, or number of fallers), LEMS, and gait parameters (walking speed, step length, or cadence) improved across both groups, suggesting that repetitive exposure to challenging balance training can lead to improvements regardless of the inclusion of external perturbations (Unger et al. 2021). In a cross-over RCT, Lotter et al. (2020) found significantly greater gains in balance confidence (ABC scale) following task-specific vs. impairment-based training, while BBS, Five Times Sit to Stand Test (FTSTS), or LEMS showed similar improvements in both groups. The authors suggested that, as training specificity may be an important component of rehabilitation interventions, therapists must educate patients on strategies to minimize the minor adverse events (AEs) shown in the trial (Lotter et al. 2020).
We found one RCT that included people with motor complete SCI. Sadeghi et al. (2019) included 16 patients with paraplegia, 12 with motor complete and four with motor incomplete SCI, who were randomly assigned to the rebound group (moderate intensity sitting or lying trampoline training) or a control group (Sadeghi et al. 2019). At the end of the intervention period (12 weeks), the rebound group achieved significant improvements in standing balance parameters (e.g., the mean values of the center of pressure excursion in the antero-posterior plane, or the velocity of center of pressure in antero-posterior), whereas the control group had no progress (Sadeghi et al. 2019).
In a pre-post study, Neville et al. (2019) assessed 10 patients with tetraplegia and five with paraplegia who performed an overground locomotor training protocol twice a week in five individualized training segments (joint mobility, volitional neuromuscular activation, task-isolation, task-integration, and activity rehearsal). At post-intervention (12 to 15 weeks), most of the participants demonstrated increased BBS scores with a mean score improvement of 4.53 ± 4.09, and several showed an improvement in SCI-FAI with a mean score increase of 2.47 ± 3.44 (Neville et al. 2019).
Several other studies have indicated that overground training for people with motor-incomplete SCI benefits standing balance and walking capacity (Oh & Park 2013). Overground training has also been integrated with a wider variety of other exercises to provide more comprehensive therapy (Jones et al. 2014a; Jones et al. 2014b), and others have suggested the additive benefits of providing visuotemporal cues during walk training (Pramodhyakul et al. 2016).
In an RCT, Brazg et al. (2017) compared high (70%-85% HRmax) vs. low-intensity training (50%-65% HRmax) in people with chronic incomplete SCI. Significantly greater improvements in peak treadmill speed, peak velocity, and VO2 peak-match were observed following high-intensity training, while changes in self-selected speeds and 6MWT approached significance, but LEMS or BBS did not change (Brazg et al. 2017).
Jayaraman et al. (2013) assessed the effects of resistance training intensity over four weeks of resistance training that targeted the bilateral knee flexor/extensor and ankle dorsiflexor/plantar flexor using an isokinetic dynamometer or specific strength training machines. For standing balance (measured by the BBS), only the group that trained at maximal intensity showed significant improvements; however, further studies should be carried out with a larger sample size to corroborate these results (Jayaraman et al. 2013).
Additionally, it should be noted that most of the overground locomotor training in ambulatory persons with incomplete SCI was performed over a flat, smooth, and firm surface, and this training condition is different from the irregular, unstable areas that patients encounter in their daily living after discharge (Amatachaya et al. 2021). In an RCT, Amatachaya et al. (2021) showed that a walking training program for four weeks (5 d/w) on a walking track with different surfaces (including artificial grass, pebbles, and soft areas), compared to overground walking training provides better results on standing dynamic balance (TUG and FTSTS), walking speed (10MWT), walking distance (6MWT), and risk of falling during 6-month follow-up (Amatachaya et al. 2021). The same research study group showed that low cognitive-motor interference (as measured by dual-task obstacle crossing) is a strong predictor of fall risk over the next six months (unadjusted odds ratio = 7.07, p<0.002, power = 1.000) in people with chronic SCI (Amatachaya et al. 2019). Incorporating cognitive-motor interference as part of an assessment and treatment program may help to identify those at risk of future falls and promote functional ability and improvement in people with SCI (Amatachaya et al. 2019).
Conclusions
There is level 1 evidence (from 1 RCT: Unger et al. 2021) that perturbation-based balance training and conventional intensive balance training provide similar improvements in reactive stepping ability (behavioral response and foot contact time during the Lean-and-Release test), lower limb strength, gait parameters, balance control (Mini-BESTest and CB&M), balance confidence (ABC Scale), fall concern (FES-I), and on falls parameters (number of falls, number of fallers, or time to first fall); compared to conventional intensive balance training, in patients with chronic motor incomplete SCI.
There is level 1 evidence (from 1 RCT: Lotter et al. 2020) that task-specific training (consisting of stepping practice) provides more improvements in balance confidence (ABC Scale) and similar improvements in patient’s ability to safely balance (BBS), compared with impairment-based training in patients with chronic motor incomplete SCI.
There is level 1 evidence (from 1 RCT: Brazg et al. 2017) that high-intensity (70%-85% HRmax) locomotor training does not provide significantly greater improvements in standing balance (BBS) compared to low-intensity (50%-65% HRmax) locomotor training in participants with chronic and motor incomplete SCI.
There is level 1 evidence (from 1 RCT: Amatachaya et al. 2021) that a walking training program for 4 weeks (5 d/w) on a walking track with different surfaces (including artificial grass, pebbles, and soft areas), compared to overground walking training yields better results on standing dynamic balance (TUG and FTSTS) and a lower risk of falling during 6-month follow-up in patients with chronic motor incomplete SCI.
There is level 2 evidence (from 1 RCT: Sadeghi et al. 2019) that rebound therapy could provide improvements in standing stability parameters (excursion, velocity, and path length of the CoP) in patients with chronic motor complete and incomplete SCI.
There is level 2 evidence (from 1 RCT: Jayaraman et al. 2013) that a 4-week lower limb resistance training program at maximal intensity (isometric contractions of maximum volitional effort) provides significant improvements in standing balance (BBS), meanwhile, a conventional resistance training program at moderate intensity (60%-65% of their one-repetition maximum) did not.
There is level 2 evidence (from 1 RCT: Jones et al. 2014a) that 24 weeks of ABT (which included developmental sequencing; resistance training; repetitive, patterned motor activity; and task-specific locomotor training) did not provide significant improvements in standing balance (TUG) in comparison with a control intervention in patients with incomplete and chronic SCI.
There is level 4 evidence (from 1 pre-post study: Neville et al. 2019) that overground locomotor training (consisting of joint mobility, volitional neuromuscular activation, task-isolation, task-integration and activity rehearsal) for 12-15 weeks provides improvements in standing balance (BBS) and in functional walking ability (SCI-FAI) in patients with chronic motor incomplete SCI.
There is level 4 evidence (from 1 pre-post study: DiPiro et al. 2016) that a 6-week progressive aerobic program (which included two steady exercise sessions at the target intensity and one high-intensity interval training session) using a recumbent cross-trainer does not provide significant improvements in standing balance in people with chronic SCI.
There is level 4 evidence (from 1 pre-post study: Oh & Park 2013) that community-based ambulation training that is progressively challenging may result in long-lasting benefits in standing balance and walking ability in people with incomplete SCI.
