## 2 Dataset Construction
### Experiment for Data Acquisition  
Figure 2 shows the experimental environment for the measurement and analysis phases under steady-state conditions. (a) Three arrows, from left to right side, indicate acceleration, consecutive, and deceleration steps for the measurement phase, respectively. (b) Detection of walking abnormalities with the shoe-type inertial measurement unit (IMU) system is analyzed through extracted features, such as heel strike (HS) and toe-off (TO) [26; 27].  
Shoe-type IMU sensor (DynaStabTM, JEIOS, Busan, Korea) consists of the data logger (Smart Balance SB-1, JEIOS, Busan, Korea) and the data acquisition device. The IMU sensor (IMU-300 TM, InvenSense, San Jose, CA, USA) in the data logger can measure triaxial acceleration (up to \(\pm 6\) g) and tri-axial angular velocities (up to \(\pm 500^{\circ}\) s  
Figure 2: Experimental environment and system for the measurement and analysis phases under steady-state conditions. (a) Three arrows from left to right sides indicates acceleration, consecutive, and deceleration steps for the measurement phase, respectively. (b) Detection of walking abnormalities with the shoe-type inertial measurement unit (IMU) system is analyzed through extracted features.  
orthogonal axes. The IMU sensors are set up on the outsoles of both shoes, and data are transmitted to the data acquisition device via Bluetooth. The walking measurement was collected at 100 Hz and filtered using a second-order Butterworth low-pass filter with the 10 Hz cut-off frequency. Although data are measured during acceleration and deceleration steps, data for these steps are ignored. Instead, data during consecutive steps are used to analyze for extraction of features.  
All subjects performed three trials of the overground walking test along the straight 15-m walkway at slower, preferred, and faster speeds wearing the shoe-type IMU sensor. The preferred walking speed is defined by someone's comfortable, stable, and usual walking speed. The subjective decision of subjects decides the slower and faster speed. Thus, the slower or faster speed is controlled 20% slower or faster under the preferred speed. The prepared metronome supports the decision of the walking speed. The subjects were asked to walk at the preferred speed to measure cadence using the metronome before each test.  
All subjects also performed four physical fitness domains with nine tests: muscle strength, flexibility, balance, and cardiorespiratory fitness. All subjects were performed grip strength with a hand-grip dynamometer (TKK 5401 Grip-D, Takei Scientific Instruments, Tokyo, Japan) and biceps curls with a dumbbell (3 kg for men; 2 kg for women) to measure upper extremity strength. Five times sit-to-stand (STS) and standing time from a prolonged sitting position were also performed to assess the lower extremity strength. To assess flexibility, back scratch as the upper extremity flexibility and chair sit and reach as the lower extremity flexibility was performed. Single-leg balance (dominant leg) as the static balance and a three-meter timed-up-and-go (TUG) as the dynamic balance were performed to assess physical abilities. Finally, a 6-min walk test was performed to assess cardiorespiratory (or functional) fitness. Two attempts of each test calculated the mean scores of physical fitness tests.