Research article - (2016)15, 352 - 357 |
Effect of Semi-Rigid and Soft Ankle Braces on Static and Dynamic Postural Stability in Young Male Adults |
Noriaki Maeda1,, Yukio Urabe1, Shogo Tsutsumi1, Shuhei Numano1, Miho Morita1, Takuya Takeuchi1, Shou Iwata1, Toshiki Kobayashi2 |
Key words: Ankle brace, static postural balance, dynamic postural balance, Dynamic Postural Stability Index |
Key Points |
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Participants |
A total of 21 healthy, young, recreationally active men [age 24.0 ± 3.6 years (mean ± SD); height 1.74 ± 0.06 m; body weight 63.1 ± 14.4 kg] voluntarily participated in this study. “Recreationally active” was defined as having participated in at least one exercise session per week during the preceding 2 months but no involvement in structured exercise training during this period (Costa et al., |
Intervention |
Subjects were assigned to three randomly ordered experimental conditions (NB, SB, SRB). Their order experimental conditions were counterbalanced across subjects. The participants performed under three brace conditions (SB, SRB, NB) in various orders on three separate days, with an intersession interval of at least 24 h and no more than 48 h between tests. Braces were fitted to each subject by a single investigator in order to minimize within-subject and between-subject variations. |
Ankle brace |
Zamst ankle braces (Nippon Sigmax Devices, Inc., Tokyo, Japan) were used in this study. The SB (Zamst FA-1) was a nylon supporter and was designed with two layers of support for weak and swollen ankles while allowing dorsiflexion/plantar flexion ( |
Test protocol |
To compare the effect of each condition, we measured both static postural sway and dynamic postural stability under SB, SRB, and NB conditions. Static postural sway was performed during single-leg standing on a single-force platform (UM-BAR; Unimec Corporation, Tokyo, Japan). Participants were asked to maintain an upright posture and place both arms on the hip for 30 seconds with their eyes open (EO) and then closed (EC). During the EO test, the participant looked forward at a wall approximately 3.0 m from the edge of the force platform. The unsupported leg was kept at approximately 30° of hip flexion and 60° of knee flexion. If the unsupported leg touched the weight-bearing foot or force platform, the trial was discarded and repeated. Statokinesigrams were obtained showing the entire range of postural sway from the central position on a chart. Dynamic postural stability was evaluated using a single-leg jump landing in the anterior direction. This approach was chosen because it demonstrated good intersession reliability: intraclass correlation ICC (3,k) was 0.86 (Wikstrom et al., The participants were instructed to perform the following actions: jump in the anterior direction using a two-footed jump over the hurdle, land on the force plate on the non-dominant limb only, stabilize as quickly as possible, place their hands on their hips once they were stabilized, and remain still for 10 second while looking forward. Upper extremity movement was unrestricted during the jump but restricted after stabilization. They were allowed three practice trials for each condition to become familiar with the single-leg jump, with 1 min of rest after testing. The jump-landing task was performed on the non-dominant leg for unilateral assessment. The non-dominant limb was the limb that was not used to kick a ball. Niu et al. ( The measurement under each condition was conducted on different days to prevent fatigue and to avoid the subject becoming familiar with the task. The trial was discarded and done over if the subject failed to jump or came into contact with the hurdle, fell upon landing, or the non-dominant limb came in contact with the dominant leg or the ground outside the force plate. All subjects were able to complete the task. Three successful trials were performed under each condition (NB, SB, SRB),. The average duration of each laboratory trial was 52.0 ± 3.0 minutes. |
Data collection |
The locus length/second (mm/s) and enveloped area (mm2) surrounded by the circumference of the wave pattern during postural sway in static postural control. Signals of static postural sway were amplified and sampled at 200 Hz via an analog-to-digital converter. The DPSI and maximum vertical ground reaction force (vGRFmax) were measured after each protocol using a force plate (AccuGait; AMTI, Hiratsuka, Kanagawa, Japan). The ground reaction force (GRF) data to calculate the DPSI in dynamic postural stability were also collected at the sampling frequency of 200 Hz. The global reference system of the laboratory was established so the anteroposterior axis was in the y-axis direction, the mediolateral axis was the x-axis, and the vertical axis was the z-axis. The GRF data were filtered using a zero-lag, fourth-order, low-pass Butterworth filter with a frequency cutoff of 20 Hz.From these filtered data DPSI was calculated using a Microsoft Excel macro. The dependent variable was the DPSI, as shown in The DPSI is a composite of the anteroposterior, mediolateral, and vertical GRFs. It provides stability indices for anteroposterior (APSI), mediolateral (MLSI), and vertical (VSI) directions. The DPSI was calculated using the GRFs generated in 3 s immediately following initial contact, which was identified as the instant when the vertical GRF exceeded 5% of the body weight. The force plate data were normalized to the body weight. This study also used raw data signals to calculate the vGRFmax, which was calculated by dividing the peak force (N) with the participant’s body weight. The mean of three successful trials for each condition was utilized for further analysis (Wikstrom et al., |
Statistical analysis |
A repeated-measures 1 (time) × 3 (NB, SB, SRB) ANOVA model was used for comparisons of locus length/second, enveloped area, and each DPSI value (DPSI, MLSI, APSI, VSI) and vGRFmax for each condition. When appropriate, follow-up analyses were performed using Bonferroni post-hoc tests. An alpha level of 0.05 was the criterion for rejection of the null hypothesis for all statistical tests. Effect sizes were calculated using the Cohen d statistic. Statistical analysis was conducted using SPSS for Windows, version 20.0 (IBM Japan Co., Tokyo, Japan). |
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In the measures of static postural sway, the locus lengths/second and enveloped areas with OE (open eye) and CE (closed eye) were no significant differences among the three brace conditions. The DPSI (APSI, MLSI, VSI) and vGRFmax for the three conditions are shown in |
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The aim of this study was to compare the effects of the SB, SRB, and NB interventions on static and dynamic postural stability in healthy young men. The primary finding of the study was that the DPSI and VSI were significantly lower with the SRB than with the SB or NB, although the APSI and MLSI remained unchanged. Therefore, our primary hypothesis was not reasonably supported. Sell et al. ( The DPSI is a composite of anteroposterior, mediolateral, and vertical GRFs. Wikstrom et al. ( To the best of our knowledge, this is the first study to show that the SRB improved dynamic postural control, compared with the results with the SB and NB. DPSI values did not differ significantly between the SB and NB conditions. Bennell and Goldie ( In this study, locus length/second and enveloped area under OE and CE conditions showed no significant difference among the three conditions. The SB and SRB seemed to have no effect on static postural control during one-leg standing. Various mechanisms, such as improvement in proprioception or exteroception and mechanical support, have been proposed to explain how SBs and SRBs may improve postural control. We could not rule out any of these mechanisms in this study. Hadadi et al. ( Some limitations in the study need to be considered. First, the subjects were untrained and not experienced with the landing technique. Second, we analyzed only healthy men. An increased number of subjects of both sexes will allow analysis by sex. And the patient with injured chronic ankle instability will analysis and compare the healthy subjects. Third, this study investigated the immediate effect of the braces. The long-term effects of the braces must be addressed in a future study. Further studies are necessary to investigate under other activities, including side jumping and cutting maneuvers. Moreover, the effect of ankle braces on muscular activities and strength should also be explored. |
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We demonstrated that the SRB had significantly lower DPSI, VSI, and vGRFmax values after landing than were seen with the SB or NB. This result indicated that the SRB had positive effects on dynamic postural stability in healthy young men. Use of SRB is thus more likely to improve the ability to maintain dynamic balance than the SB or NB. Athletic trainers and athletes are advised to consider the effect of each ankle brace in regard to preventing ankle sprains because each ankle brace may have a positive but different effect on dynamic postural stability after landing on a single leg. |
ACKNOWLEDGEMENTS |
None of the authors has any conflicts of interest associated with this study. The author had no financial affiliations and/or involvement with any commercial organization. |
AUTHOR BIOGRAPHY |
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REFERENCES |
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