Our study demonstrates that a single session of exercise with the EX1 improved physical functions. In addition, positive results of the EX1 were confirmed by conducting a usability and satisfaction survey after exercise with EX1.
In this study, statistically significant improvements in gait speed, balance ability, and gait endurance were confirmed through a single session of exercise with the EX1. The results of this study suggest that a single session of exercise with the EX1 has several key advantages for physical function and efficiency. Functional exercise that is effective for improving gait function includes gait exercise at various speeds and directions, treadmill gait, and stair climbing. In addition, the resistance and assistance of the EX1 can be adjusted based on individual physical ability. Therefore, it improves physical function gradually by controlling the intensity and duration of the exercise.
To determine gait quality, we used objective, sensitive, and powerful measurement tools that measure gait performance, dynamic balance ability, and gait endurance . In our study, there was a statistically significant improvement in gait speed. Previous studies have shown that lower gait speed is associated with age, education, and particularly modifiable factors such as impairment of activities of daily life, physical inactivity, and cardiovascular disease . Gait speed is a clinical indicator related to survival rate and predicts functional ability in the elderly . In a previous study, it was reported that gait speed increased by 0.1 m/s as the survival rate increased . These results indicate the importance of staying active and healthy for middle- and old-aged people.
Balance ability, an essential factor in gait ability, is the ability to maintain balance against numerical movement and external stimuli, which reduces muscle weakness due to decreased physical activity and is highly associated with risk of fall due to dynamic balance ability during gait [29, 30]. Physical changes due to aging lead to a decrease in gait function by reducing balance, and it is highly related to the incidence of injuries in the elderly . In our study, a statistically significant improvement was shown in dynamic balance ability through a single session of exercise with the EX1. Falling is a serious problem that threatens the health of the elderly and can lead to premature death due to physical damage, psychological dysfunction, and onset of various diseases . Preventing falls and improving body function require planned and consistent exercise. Decreased physical activity leads to muscle strength weakness, which causes reduced balance ability. Balance training is an essential element in an exercise program because it is highly correlated with risk of falls according to dynamic balance ability while walking.
Gait endurance is also one of the major factors influencing risk of falls in the elderly. It is known that the weaker is the walking endurance, the higher is the likelihood of a fall in the elderly. In our study, endurance improved immediately after a single session of exercise with the EX1 in both age groups, but a significant result was found only in the middle-aged group. Endurance is increased through long-term gait training , but in our study, time was insufficient to derive significant results with a single session of exercise with the EX1. However, although it was not significant after single session of exercise, walking distance for 6 minutes improved, indicating the potential for positive results with long-term exercise.
SPPB is a fast and useful measurement tool for predicting falls . In our study, SPPB improved immediately in the old-aged group after a single session of exercise with the EX1, but no significant result was shown due to the ceiling effect in the middle-aged group.
This study was performed to confirm the usability and satisfaction of the EX1. Considering user physical condition and environment, it was divided into user questionnaire evaluation and user function evaluation, and the safety, operability, and satisfaction of the EX1 were evaluated. If an expert or designer conducts a usability evaluation while listening to users' opinions, it is possible to understand the user's needs, inconveniences, strengths, and expectations in a complex way. Regression analysis showed a difference in the experience feedback for the EX1 by age or physical function. However, there were no implications for usability, perceptions, or satisfaction with general characteristics other than age.
As the results of the questionnaire including usability and satisfaction, both middle- and old-aged groups had positive experience feedback for the EX1. Among them, more positive results were shown in the middle-aged group than the old-aged group in a few items. We think that these results were caused by middle-aged people being more open-minded and faster to learn new technologies than the elderly. In the questionnaire, both assist and resistance modes of the EX1 helped with gait, with strongly positive answers in the middle-aged group compared to the old-aged group. In addition, in a questionnaire on the preference between assist and resistance modes of the EX1, the old-aged group preferred assist mode, but the middle-aged group preferred resistance mode. These results indicated that the elderly, who have a decline in gait ability, prefer gait assist, but middle-aged people who need gait training prefer the resist mode of the EX1.
In regression analysis between general characteristics and questionnaire, users tended to think that using the EX1 would have no negative social perceptions if they thought they had lower health conditions. Younger users tend to have positive opinions of the EX1. Although there might be perceptions that exercise using robots is applied only to patients or the elderly [35, 36], this study confirmed that healthy people had positive perceptions of exercise with robots. Therefore, we think that the EX1 can provide a meaningful exercise program not only for the elderly, but also for young people. In regression analysis between questionnaire and physical function, people who experienced a fall within 6 months had better balance ability and physical function after a single session of exercise with the EX1. It was confirmed that the higher was the satisfaction with the function of the robot, the better were the physical endurance and dynamic balance. We think that such exercise will bring positive results when applied to people with reduced balance ability, which is a risk factor for falls.
We designed this study as a short-term functional and satisfaction evaluation of the EX1. In addition, this study was conducted only with healthy subjects. Thus, usability and satisfaction of the EX1 with subjects with declined physical function and long-term use must be addressed in further studies.