Intervention

A side-alternating vibrator (Galileo 2000, Novotec, Germany, 2011) was used and safety guidelines were explained to the participants before the experiment. WBV-TT was performed based on a previous study that had performed the WBV stimulation with a maximum frequency of 30 Hz and amplitude of 3 mm for 45 seconds and 4 sessions for post-acute stroke [16]. Before conducting the main exercise, the subjects performed stretching exercises for 15 minutes. While standing on the vibration platform, subjects placed their feet parallel to the axis. The participants performed the exercises while lightly holding a support bar always located in front of them. The WBV-TT was performed 3 times a week (4.5 minutes per session) for 6 weeks. Each session included 6 exercises and each exercise was conducted for 45 seconds. A break time of 1 minute was given between the exercises [16]. The frequency was increased gradually by 5 Hz every 2 weeks, from 20 Hz to 30 Hz, because many researchers have demonstrated its therapeutic effect [15,18]. The exercise program was composed of left and right weight shifts (weight shift to the affected side as much as possible), squats (knee joint 45° flexion), anteroposterior weight shift exercises (lifting and lowering the heel), forward lunges (flexion of the affected leg forward), one-leg standing (lifting the affected and less affected leg alternately), and deep squats (knee joint 90° flexion) (Table 1).

Whole body vibration.

A treadmill (Track Star, Incheon, Korea, 2011) was used for gait training. All participants started at a 0% slope and a minimum speed of 0.8 km/h, and were fitted with a no-body-weight support harness for safety and allowed to hold a support bar if necessary. Based on the studies of Lau and Mak (2011), the participants defined their maximum walking speed on the first day of every week and it was increased gradually by 5% during the walk [19]. They walked for 20 minutes and were constantly observed by a physical therapist while walking on the treadmill.