Effect of a controlled starting position on the relationship between the forward reach distance and movement distance of the center of pressure in the functional reach test using the ankle joint strategy

Abstract

[Purpose] This study aimed to clarify whether the distribution range of the forward reach distance and the relationship between the forward reach distance and the movement distance of the center of pressure differed depending on whether the controlled starting standing position during the functional reach test with an ankle joint strategy. [Participants and Methods] Sixteen healthy male volunteers participated in the study. The distribution range of the forward reach distance and the relationship between the forward reach distance and movement distance of the center of pressure in the controlled starting standing position and non-controlled starting standing position conditions were analyzed. [Results] The distribution range of the forward reach distance was significantly smaller in the controlled starting standing position than in the non-controlled starting standing position. In both groups, the forward reach distance was associated with the movement distance of the center of pressure. [Conclusion] The findings suggested that the use of an ankle joint strategy with a controlled starting standing position in the functional reach test may be a more accurate method to evaluate standing balance ability.

Effect of controlled start position on the reach distance distribution range in the functional reach test among community-dwelling older adults

“…In Measurement 2, the FRT was performed under two conditions: CSP and non-CSP. Reflex markers were affixed to the participants’ right acromial process (one marker in the resting standing position and another one at 90° flection of the upper limbs), great trochanter, processus styloideus ulnae, and third metacarpal head before the anterior reach measurement 17 ) .…”

“…Consequently, results have been inconsistent regarding the relationship between reach distance and SBA in older adults. One reason for the lack of consistent results may be that the start position in the FRT is typically not well controlled 15 , 16 , 17 ) . Duncan et al 18 ) reported that only the foot position was controlled as the start position in the FRT.…”

“…Older adults tend to develop a thoracic kyphosis posture as they age 19 , 20 , 21 ) , and this postural change has been reported to increase their center of gravity (COG) sway due to their inability to hold their COG in a fixed position while keeping a standing position 22 , 23 ) . Furthermore, Nishimura et al 17 ) reported that the start position differed from one execution to another because of body sway, resulting in an error in the reach distance measurement when only the feet were controlled. Therefore, in FRT assessments of older adults, the start position tends to fluctuate from one session to another, particularly in postural changes such as thoracic kyphosis.…”

“…In the FRT of young adults, it has been reported that the reach distance distribution range (RDDR) was reduced when the controlled area other than the foot was used as the start position 16 , 17 ) . Therefore, even in the FRTs of older adults, controlling a position other than the foot as the start position may minimize the increase in COG sway associated with a thoracic kyphosis posture.…”

“…Controlling the start position, in turn, would enable a more accurate measurement of the reach distance by reducing the RDDR. Therefore, the validity of the FRT must be analyzed with a controlled start position (CSP) 17 ) in older adults, especially considering the inconsistent results regarding conventional FRT measurement methods in relation to standing stability.…”