musculoskeletal stiffness and limited range of motion ( rom ) can restrict functional joint 
 movement , particularly during ankle supination following neurological diseases1 . ankle dorsiflexion rom restrictions impair 
 dynamic balance and gait , which may contribute to secondary injuries ; reduced ankle rom and 
 tight calf muscles can cause poor gait , inefficient energy use , impaired balance , and an 
 increased risk of falls2 . musculoskeletal 
 transformations manifesting as abnormal joint stiffness and limited rom result in numerous 
 restrictions in the function and joint movements of patients3 . limited passive ankle dorsiflexion rom during knee extension can 
 alter foot positioning and result in compensatory foot movements , leading to an abnormal 
 gait , which can result in ankle sprains and lower extremity overuse injuries4 . studies have reported that balance - training 
 programs that alter the somatosensory input , such as the use of an unstable surface to 
 induce equalized weight distribution , can be helpful in hemiplegic patients5 . kim et al . used an ankle board with a slope 
 in their center to achieve efficient ankle stretching and increased dorsiflexion6 . they suggested that stretching exercises 
 using their device resulted in a greater increase in foot pressure compared to that with 
 stretching exercises using existing inclined boards during ankle dorsiflexion 
 stretching6 . therefore , we investigated 
 the effects of an unstable inclined board on the active and passive ankle rom in patients 
 with ankle stiffness . the study included 10 female patients ( mean age , 22.8  5.3  years ; height , 158.9  3.0  cm ; 
 weight , 61.2  4.7  kg ) with ankle stiffness caused by diseases or medical conditions . the 
 patients were selected based on ankle stiffness scores obtained using a symptom checker 
 tool . the patients were assigned randomly to two groups ( both n = 5 ) and their height and 
 weight were measured . the patients were not cognitively impaired and were capable of 
 independent walking for 20  m without difficulty . patients were excluded if they had a 
 history of or current neurological conditions . before participating , the purpose and methods 
 of the study were explained to the patients , and all provided informed consent , according to 
 the principles of the declaration of helsinki . active and passive ankle dorsiflexion were measured using a standard 31.75  4.45  cm clear 
 plastic goniometer , with one increment , a 360 scale , and a bubble level at each end . group 
 1 performed the ankle dorsiflexion stretching exercise using a wooden inclined board , and 
 group 2 performed ankle dorsiflexion stretching exercises using an air - cushioned inclined 
 board that provided an unstable surface . rubber sheets were attached to the inclined boards to prevent falls due to 
 sliding . the patients performed ankle dorsiflexion stretching exercises for 5  min , with a 
 10-min rest between each set , five times a day for 1 week . the active and passive ankle 
 dorsiflexion angles were measured bilaterally using the goniometer before and after the 
 study . independent and paired t - tests were used to assess within- and between - group differences in 
 ankle dorsiflexion , with spss for windows ( spss , chicago , il , usa ) . the amount of active and passive dorsiflexion did not differ between the two groups before 
 the exercises , with active dorsiflexion angles of 18.2  6.4 and 19.3  4.2 and passive 
 dorsiflexion angles of 23.4  5.5 and 22.6  5.7 in groups 1 and 2 , respectively ( both p 
 > 0.05 ) . the stretching exercises significantly ( p < 0.05 ) increased the active and 
 passive ankle dorsiflexion angles in both groups compared to those at baseline . the active 
 dorsiflexion angle was significantly increased ( p < 0.05 ) in group 2 compared to that in 
 group 1 after the exercises . the active dorsiflexion angles before and after the exercises 
 were 18.2  6.4 and 22.1  5.0 in group 1 and 19.3  4.2 and 28.1  6.9 in group 2 , 
 respectively . the passive dorsiflexion angles did not differ significantly between the 
 groups after the exercises ( p>0.05 ) and were 23.4  5.5 and 32.2  5.3 in group 1 and 
 22.6  5.7 and 35.1  6.0 in group 2 before and after exercising , respectively . the 
 air - cushioned inclined board provided an unstable surface for performing ankle dorsiflexion 
 stretching exercises . the results showed that ankle stretching exercises using the unstable 
 inclined board significantly increased the active dorsiflexion angle compared to that with 
 exercises using a wooden inclined board . we believe that the use of the air - cushioned 
 inclined board provides somatosensory input and subsequently stimulates active ankle 
 dorsiflexion by promoting automatic postural control . sensory proprioception of the ankle 
 and sensory compression of the plantar are important in the control of sway7 . an increase in the number of somatosensory 
 inputs affects the muscles , and the use of an unstable support surface result in many 
 different somatosensory inputs that limit compensatory action7 . performing cognitive tasks in a standing posture reduces internal 
 focus and induces external focus , which promotes automatic postural control8 . stretching improve the flexibility of 
 tendons , and changes in the mechanical condition of tendons depend on the type of stretching 
 performed9 . , the passive dorsiflexion angles did not differ significantly between the two 
 groups after ankle stretching exercises . however , stretching exercises significantly 
 increased the active and passive ankle dorsiflexion angles in both groups compared to those 
 at baseline . these results suggest that passive ankle exercises using a wooden inclined 
 board only stretch muscle and tissue , while exercises using an unstable inclined board 
 stretch muscle and tissue , and stimulate activation of the ankle dorsiflexor . active ankle 
 dorsiflexion was more effectively improved with ankle stretching exercises using an unstable 
 inclined board than with exercises using a wooden inclined board .
[ purpose ] the present study assessed the effects of using an unstable inclined board on 
 the active and passive ankle range of motion in patients with ankle stiffness . [ subjects ] 
 the study included 10 young female patients with ankle stiffness . 
 [ methods ] the patients 
 were divided into the following two groups : a group that performed ankle dorsiflexion 
 stretching exercises using a wooden inclined board and a group that performed stretching 
 exercises using an air - cushioned inclined board ( unstable inclined board ) . 
 active and 
 passive ankle dorsiflexion angles were measured bilaterally using a goniometer . 
 [ results ] 
 both inclined boards significantly increased active and passive ankle dorsiflexion . 
 after 
 performing ankle stretching exercises , active dorsiflexion significantly increased the 
 unstable inclined board compared to that using the wooden inclined board . 
 however , the 
 passive dorsiflexion angles did not differ significantly between the two groups after 
 ankle stretching exercises . 
 [ conclusion ] the use of an unstable inclined board might 
 stimulate activation of the ankle dorsiflexors in addition to stretching muscle or tissue . 
 active ankle dorsiflexion was more effectively improved with stretching exercises using an 
 unstable inclined board than with exercises using a wooden inclined board .