# HAL Training in Spinal Cord Injured Patients: A Narrative Review of 10 Years Experience
## 3 Results
### Clinical Trials
[12] it is mainly postulated that the neurological and ambulatory recovery depends on a pa tient's lesion level and age, as well as their initial AIS grade whereby low AIS grade and age \(\geq\) 50 years seem to be negative predictors for functional recovery following SCI. In order to investigate this in relation to HAL training a study was set up with the aim to compare the functional outcomes of patients with chronic SCI (1 to 20 years since SCI) in four injury-level groups and additionally analyze results as a function of age (<50 years vs. \(\geq\)50 years) [12]. The four groups were classified as (1) incomplete tetraplegia (\(n\) = 13, C2-8, AIS C and D), (2) incomplete paraplegia with spastic motor behavior (\(n\) = 15, T2-12, AIS C and D), (3) complete paraplegia with an absence of spastic motor behavior (\(n\) = 18, T11-L4, AIS A and ZPP from L3 to S1), and (4) incomplete paraplegia with an absence of spastic motor behavior (\(n\) = 9, T12-L3, AIS C and D) [12]. A total of 55 participants were involved. As part of the Ruhr-University Bochum group, the same training program (12 weeks, 5 units/week) was completed and the results of the initial eight patients from [PERSON] et al. [9] and in part from [PERSON] et at. [11] were also included. As seen in the other studies [9; 10; 11], the cohort improved in treadmill related and functional parameters. In contrast, however, to the assumptions made in the literature, the lesion level and patients' age were not significantly associated with training-related functional improvements. No significant differences between subgroups were found. Subgroup 2 showed slightly less improvement in treadmill walking speed, treadmill distance and 6 MWT, but these differences were statistically not significant [12]. Concerning patients' age only 10 MWT-speed showed a significantly larger improvement in the younger group compared to the older group. Another interesting finding of this study was that most improvements occurred during the 4 th and 10 th week of the training period [12]. From the results demonstrated here, the authors conclude that older age or lesion level seem to be less important in terms of the extent of functional improvement following HAL training. Nevertheless, incomplete SCI lesions of the thoracic spine, including spastic motor behavior, appear to be a non-significant negative predictor for training-related improvements [12]. To examine long-term data of variable-frequency HAL training after the initial training period, it was again [PERSON] et al. [13] who followed up the pilot study of [PERSON] et al. [9] with one year of HAL training. All eight chronic SCI participants continued HAL training after their initial training period of 12 weeks and were divided into two groups. Group 1 (\(n\) = 4) continued with 3-5 training sessions per week for a further 40 weeks and group 2 (\(n\) = 4) continued with one session per week. In the first 12 weeks, the participants had 51.75 \(\pm\) 5.6 training sessions on average. During the second training period, the mean number of training sessions in group 1 was 126.8 \(\pm\) 7.9 and 32.3 \(\pm\) 3.3 in group 2. Results were given both for the first training period (repetition of [PERSON] et al. [9] results) and after one year of treatment. In order not to be redundant, we here only discuss new results after one year. Concerning treadmill related parameters (speed, walking time, and distance) no significant improvements were demonstrated between 12 and 52 weeks results for evaluation as a total group (\(n\) = 8), as individual groups (\(n\) = 4/4), and for comparison between subgroups. The same was seen in the functional testing. Considering all eight patients together, irrespective of continuous training frequency during the following 40 weeks, there were no significant changes for 10 MWT, cadence, number of steps, step length, TUG, 6 MWT, or WISCI II. Taking into consideration the two subgroups separately, there was no difference between 12 and 52 weeks and no difference between the groups.