This study was conducted to assess the effect of electromechanical-assisted gait training intensity on walking ability in stroke patients. The intensity of gait training was defined according to the intervention time per session because electromechanical-assisted gait training could provide unlimited repetition and most accurate motion. Thus, the data of two RCTs which had the same study design of intervention and evaluation except intervention time per session were recruited; 30 minutes for 4 weeks (RCT 1) and 60 minutes for 2 weeks (RCT 2). Because the improvement of walking ability in RCT 1 and RCT 2 was not different after matching the inclusion criteria and total intervention time, we suggested that intensive gait training could shorten the gait training period.
Mehrholz et al.  investigated 36 trials of electromechanical-assisted gait training involving 1472 participants and concluded that electromechanical-assisted gait training in combination with physiotherapy increased the odds of participants becoming independent in walking, but did not significantly increase their walking velocity or walking capacity. However, they interpreted the results with caution, because some trials investigated people who were independent in walking at the start of the study, and they found differences between the trials in terms of the duration of intervention and frequency. It is still uncertain what is the most effective frequency and intervention time of electromechanical-assisted gait training. This study hypothesized that training intensity might be based on the number of repetitions during walking movement, and high-intensive gait training could improve walking ability more than low-intensive gait training. However, the improvements of walking ability by high and low intensive gait training were not different if providing the same total intervention time.
Most studies applied the intervention time for around 30 minutes per day or session [18–22] because it is a tolerable exercise time for stroke patients. However, a few studies tried the intervention time for 60 minutes per session [21, 22] and it was tolerable for chronic stroke patients who could walk with or without help. Bang and Shin  reported that chronic stroke patients who had robot-assisted gait training for 60 minutes a day, 5 days a week, for 4 weeks, showed better walking abilities and balance than those who had treadmill gait training. However, Stein et al. reported that robotic therapy for ambulatory stroke patients with chronic hemiparesis using a robotic knee brace resulted in only modest functional benefits that were comparable to those from a group exercise intervention, although they did the robot therapy for 60 minutes a day, 3 days a week, for 6 weeks . We also tried intensive 60-minute gait training to get a better result by increasing the intervention time per session and found that the 60-minute electromechanical-assisted gait training improved ambulatory function as much as the physical therapist-assisted gait training although the improvements did not meet the minimally clinically important difference .
Stroke patients who could walk with another’s assistance (FAC 2, 3) or requiring help (FAC 4, 5) were included in this study. Chronic stroke patients who could walk with help participated actively in RCT 2 because they wanted walk well. And they could tolerate 60-minute gait training and eagerly wanted to obviate the need for a cane or another’s assistance. This study had new inclusion criteria of the chronic patients who had stroke duration over 3 months and those who could walk help. The patients of FAC 6 in RTC 2 who could walk independently were excluded, because they could walk without help and did not expect further improvement of FAC. Although RCT 2 had provided additional gait training of 2 weeks for the consented patients, the outcome measures at the end of additional gait training were not different from those at the end of initial gait training of 2 weeks . Thus, this study adopted the outcome measures at the end of gait training of 2 weeks in the RCT 2.
We intended to find out whether we could shorten the gait training period if providing the electromechanical-assisted gait training intensively, because Exowalk® could provide unlimited repetition and most accurate motion. This study found the same improvement of walking ability after 2 or 4 weeks of gait training if providing the same total intervention time. However, the improvement of mobility by low-intensive gait training of 4 weeks was better compared to high-intensive gait training of 2 weeks. The improvement of muscle strength and balance were also significant in low-intensive gait training, but did not reach the statistical significance (p = 0.090, p = 0.99). Because the patients in this study were old and chronic hemiplegia or hemiparesis, the long period of gait training intervention might be beneficial for improving mobility. RMI is a test to assess mobility based on 15 items ranging from turning over in bed to running. It includes both walking ability and daily activity. While walking velocity and capacity improved in both LI and HI groups, the daily activities in the LI group improved more than those in HI group. Because the daily activities of lying, sitting and bathing needed muscle strength and balance, the change of RMI in LI group was greater than that in HI group.