Overground Training for Gait Rehabilitation

Overground gait training (OGT) has been the predominant approach for regaining walking function, until recent years when the emphasis shifted to other forms of locomotor training (LT) (Mehrholz et al. 2017). Overground walking training (OWT) does not require expensive devices, and it more closely resembles natural walking conditions in daily life compared to walking on a treadmill (Yu et al. 2019). It is most likely in people with motor incomplete SCI and is used when there is improved neuromuscular capacity and/or a readiness to walk at home and in the community. Though overground training is often used as a control group for other types of treatment (e.g., treadmill training), some studies assessed a progressive approach to overground training.

Discussion

Overground training provides an important mode of exercise for improving walking function, other physical and mental functions (e.g., muscle strength, bone health, cardiovascular function, or depression symptoms), and is helpful for ambulating at home and in the community.

In a systematic review, Mehrholz et al. (2017) compared the effectiveness of 13 trials of BWSTT and RAGT with OGT and other forms of physiotherapy on walking speed and walking distance in people with traumatic SCI. The results indicated that neither BWSTT nor RAGT increases walking speed more than OGT and other forms of physiotherapy (Mehrholz et al. 2017). The authors noted that an increase in walking speed of 0.04 and 0.13 m s^-1 was sufficiently meaningful to justify the additional cost of BWSTT and RAGT (Mehrholz et al. 2017). The results for walking distance were similar, so it was not possible to rule out that BWSTT or RAGT improve walking distance more than OGT and other forms of physiotherapy (Mehrholz et al. 2017).

Several studies have indicated that overground training benefits functional walking capacity for people with motor-incomplete SCI (Forrest et al. 2014; Amatachaya et al. 2021; Senthilvelkumar et al. 2015). Overground training has also been integrated with a wider variety of other exercises to provide more comprehensive therapy (Jones et al. 2014a), and others have suggested the additive benefits of providing visuotemporal cues during walking training (Pramodhyakul et al. 2016). Lotter et al. (2020) included 10 patients with tetraplegia and 6 with paraplegia who were randomly allocated to an intervention training consisting of 20 training sessions of up to 40 min over < 6 weeks and in either task-specific or impairment-based training. Task-specific training consisted of stepping practice in variable contexts (such as overground), and impairment-based training consisted of non-walking interventions (including strengthening, aerobic conditioning and practice of transfers) (Lotter et al. 2020). During the intervention, the task-specific training group achieved higher stepping parameters than impairment-based training, but average and maximum rate of perceived exertions (RPEs) were similar between groups (Lotter et al. 2020). After the intervention, significantly greater gains in the fastest speed over short distances, peak treadmill speed, and 6MWT were observed following task-specific vs. impairment-based training, while Berg Balance Scale (BBS), FTSTS test or LEMS showed similar improvements in both groups (Lotter et al. 2020). Although there were no serious adverse events (AEs) during training, minor AEs during task-specific training were significantly higher than in impairment-based training, with specific differences including a greater number of falls (Lotter et al. 2020). The authors noted that, as training specificity may be an important component of rehabilitation interventions, therapists must educate patients on strategies to minimize the AEs shown in the trial (Lotter et al. 2020).

Additionally, it should be noted that most of the overground LT 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 4 weeks (5 d/w) on a walking track with different surfaces (including artificial grass, pebbles, and soft areas) provided significant improvements at the end of the program on walking speed (10MWT), walking distance (6MWT), and risk of falling; conversely, the control intervention (OWT) did not provided significant improvements. However, there were no significant differences after 6 months of follow-up for both training programs (Amatachaya et al. 2021).

Evans and Field-Fote (2024) explored the relationships among walking outcomes in a subgroup analysis of slow (n = 15) vs fast (n = 10) walkers. Over three consecutive days, participants performed an MST intervention (Evans & Field-Fote 2024). Among the full sample, MST was associated with increases in walking speed, step length, step frequency, and a decrease in the walk ratio (step length/step frequency) (Evans & Field-Fote 2024). In addition, a relative change in walking speed and step frequency was higher among slow vs fast walkers (Evans & Field-Fote 2024).

In a pre-post study, Liu et al. (2021) tested whether 320 patients with acute and complete (AIS A) SCI after intradural decompression surgery and assessed the effects of a weight-bearing walking training program, called 3-5-6 Kunming Locomotor Training Program. This program was performed in 3 1-h sessions, 5 days per week, for 6 months, and was made up of 8 progressive steps from 1) training to stand with weight support when a trainer fixes the knees, to 8) training to walk without any support (Liu et al. 2021). The authors reported that the intervention was safe, as none of the patients’ postoperative conditions worsened after surgery and weight-bearing walking training. There were significant improvements in locomotor scores at 15 days, 3 months, and 6 months for people with lumbar and thoracic level injuries; people with cervical level injuries showed improvements at 15 days and 3 months only (Liu et al. 2021).

Despite the established role of cardiovascular intensity in the field of exercise physiology, its role in the physical rehabilitation of patients with neurologic injury has emerged only in the past 15 to 20 years (Fahey et al. 2022). Regarding walking recovery, the RCT of Brazg et al. (2017) included people with chronic motor incomplete SCI compared high (70%-85% HR_max) vs. low intensity training (50%-65% HR_max) by altering the biomechanical demands of walking, with equivalent total stepping practice. Consistent with previous studies in patients’ post-stroke (Ivey et al. 2015), significantly greater improvements in peak treadmill speed, peak velocity, and VO₂peak-match were observed following high-intensity training, while changes in self-selected speeds and 6MWT approached significance, but LEMS or BBS did not change. It should be noted that there were no AEs during both interventions and that the intensity of stepping exercise can be readily manipulated and indirectly monitored using cardiopulmonary and subjective measures in clinical settings (Brazg et al. 2017).

Conclusions

There is level 1 evidence (from 1 RCT: Senthilvelkumar et al. 2015) that overground and treadmill-based training are comparable.

There is level 1 evidence (from 1 RCT: Lotter et al. 2020) that task-specific training (stepping practice in different contexts such as overground training) provides more improvements in fastest speed over short distances, peak treadmill speed, and 6MWT compared with impairment-based training in patients with chronic 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 OWT yields better results on walking speed (10MWT), walking distance (6MWT), and a lower risk of falling during 6-month follow-up in patients with chronic motor incomplete SCI.

There is level 1 evidence (from 1 RCT: Brazg et al. 2017) that high-intensity (70%-85% HR_max) LT (composed of speed-dependent treadmill training, skill-dependent treadmill training, overground training, and stair climbing) provides significantly greater improvements in selected locomotor variables (peak treadmill speed and fastest-possible speeds) and combined metabolic capacity and efficiency (VO₂peak) compared to low-intensity (50%-65% HR_max) LT in participants with chronic and motor incomplete SCI.

There is level 2 evidence (from 1 prospective controlled trial: Evans & Field-Fote 2024) that three consecutive days of moderate-intensity MST (overground exercises performed as a circuit) provides significant increases in walking speed, step length, and step frequency, and a significant decrease in the walk ratio (step length/step frequency) in patients with motor-incomplete and chronic SCI.