This paper proposes a scheme for predicting ground reaction force (GRF) and center of pressure (CoP) using low-cost FSR sensors. GRF and CoP data are commonly collected from smart insoles to analyze the wearer\'s gait and diagnose balance issues. This approach can be utilized to improve a user\'s rehabilitation process and enable customized treatment plans for patients with specific diseases, making it a useful technology in many fields. However, the conventional measuring equipment for directly monitoring GRF and CoP values, such as F-Scan, is expensive, posing a challenge to commercialization in the industry. To solve this problem, this paper proposes a technology to predict relevant indicators using only low-cost Force Sensing Resistor (FSR) sensors instead of expensive equipment. In this study, data were collected from subjects simultaneously wearing a low-cost FSR Sensor and an F-Scan device, and the relationship between the collected data sets was analyzed using supervised learning techniques. Using the proposed technique, an artificial neural network was constructed that can derive a predicted value close to the actual F-Scan values using only the data from the FSR Sensor. In this process, GRF and CoP were calculated using six virtual forces instead of the pressure value of the entire sole. It was verified through various simulations that it is possible to achieve an improved prediction accuracy of more than 30% when using the proposed technique compared to conventional prediction techniques.

BACKGROUND: The center of pressure (COP) excursion parameters are recognized as risk factors for the etiology and development of patellofemoral pain (PFP). The purpose of the present study measures the effect of pain exacerbation on COP excursion, and the correlation between pain intensity and COP excursion in women with PFP during single leg squat (SLS).
METHODS: Sixty patients with PFP participated in this cross-sectional study. The outcome measures were included pain intensity and COP excursion which evaluated in pre and post pain exacerbation during SLS. The COP parameters were evaluated during single leg squat in 60° of knee flexion. A paired t-test and MANOVA was used to compare pain intensity and COP excursion between the two conditions, respectively. Furthermore, A Pearson\'s correlation matrix was used to examine the relationship between pain intensity with COP excursion.
RESULTS: Statistical analysis showed that pain intensity (t = - 16.655, p < 0.001) and COP excursion (Wilks\' Lambda = 0.225, p < 0.001) with medium effect size increased after PFJ loading. In addition, an excellent positive correlation was observed between increased in pain intensity and COP excursion (P < 0.001, r > 0.80).
CONCLUSIONS: After PFJ loading, women with PFP presented increases in the pain intensity, COP excursions, and sway velocity. In addition, there was an association between the increase in pain intensity and COP excursions. Clinicians aiming to improve postural control of patients with PFP could use kinesio taping as a short-term intervention and balance training to improvements in postural control at medium and long-term. Furthermore, emphasizing psychological factors to reducing kinesiophobia can be useful to restoring proper movement pattern, reducing pain and improving symptoms.

Purpose: This study aimed to evaluate the effects of high-heeled shoes (HHS) and experience with such footwear on foot loading and standing balance using linear and nonlinear methods. Methods: Sixteen young female experts in wearing high-heeled shoes (HHE) and sixteen young females who occasionally wore high-heeled shoes (HHO) completed a Fall Risk Test (FRT) on the Biodex Balance System platform. They also underwent a both-leg standing test on the Zebris pressure mapping platform, both barefoot and while wearing 11 cm HHS. The study analyzed several parameters, including the FRT index, foot loading parameters, linear measures of postural stability (Center of Pressure (CoP) path length and velocity), and nonlinear postural control measures (sample entropy - SampEn, fractal dimension - FD, and the largest Lyapunov exponent - LyE). Results: HHS caused a significant increase the fall risk of more than 44%, but only in the HHE group. The presence of HHS caused a significant increase in CoP path length and CoP velocity by almost 78%. The values of these parameters increased by more than 67% in the HHO group and by more than 92% in the HHE group. HHS caused a significant increase in the values of nonlinear measures (FD and LyE) in the mediolateral direction. Higher FD and LyE values suggest the ability to react faster to destabilizing stimuli and better balance control related to plasticity and adaptability to new conditions. HHS also led to up to 70% loading on the supporting limb. Conclusions: High heels in the population of young women significantly worsen static balance.

UNASSIGNED: Differences in motor control between the lower limbs may influence the risk of sports injury and recovery from rehabilitation. In this study, differences in the visual feedback ability of the left and right lower limbs were assessed using visual target tracking tasks.
UNASSIGNED: Thirty-four healthy young subjects (aged 20.4 ± 1.2 years) were asked to move their bodies back and forth while tracking a visual target displayed on a monitor in front of them for 30 s. The two target motions were sinusoidal (i.e., predictable patterns) and more complex (random) patterns. To assess the ability of the lower limbs to follow visual target tracking, antero-posterior CoP (right limb, CoPap-r; left limb, CoPap-l) and medio-lateral CoP (right limb, CoPml-r; left limb, CoPml-l) data were measured using a stabilometer. Tracking ability by visual feedback ability was calculated as the difference in displacement between the target signal and the trajectories of the right and left pressure centers as trapezoidal areas, and a smaller sum of area (SoA) over the entire measurement time was defined as a greater tracking ability.
UNASSIGNED: Regarding the SoA in the anterior-posterior CoP, the mean SoA in the sinusoidal and random tasks was significantly lower in the CoP-r data than in the CoP-l data, indicating that the right lower limb had a more remarkable ability to follow visual target tracking. Regarding the SoA in the medial-lateral direction (CoP), the mean SoA in the sinusoidal and random tasks did not significantly differ between the two legs.
UNASSIGNED: The right lower limb may have a tracking function activated by the target signal when responding to visual stimuli. Identifying the motor strategies of each lower limb in response to visual stimuli will not only help identify potential differences between each lower limb but also suggest the possibility of enhancing the role of each lower limb in balance control.

OBJECTIVE: This study compared postural control and neuromuscular activation in athletic swimmers (A-S) and non-athletic swimmers (N-A-S) in older children.
METHODS: Ten A-S and ten N-A-S underwent assessments of center of pressure (CoP) parameters under static and dynamic surfaces in two directions (dynamic mediolateral (DML) and dynamic anteroposterior (DAP)) in eyes-open (EO) and eyes-closed (EC) conditions, and electromyography (EMG) parameters under DAP and DML directions in EO and EC conditions.
RESULTS: Results showed that A-S demonstrated significantly superior postural control (p < 0.05), with smaller CoP area and lower CoP mean velocity compared with N-A-S, particularly in static with EC, DAP with EO and EC, and DML with EO conditions. A-S exhibited significantly larger neuromuscular activation amplitudes (p < 0.05), especially in the AP direction.
CONCLUSIONS: These findings suggested that athletic swimming training may enhance postural control and neuromuscular activation in 11-13-year-old children, emphasizing the potential benefits of incorporating swimming exercises in these children.

A three-partition distributed force platform (3P-DFP) is proposed to measure the plantar pressure distribution, and foot support characteristics are evaluated with the obtained pressure distribution information. Twenty-seven young adults and 40 elderly adults were randomly recruited to perform the test in three phases: double-leg stance with eyes closed, double-leg stance with eyes opened, and single-leg stance with eyes opened. The evaluation parameters of foot support surface characteristics and support point characteristics were calculated based on the average position information of the center of pressure in the lateral of sole, media of sole, posterior of heel, and entire pelma. The results showed that the support width of the foot sole was significantly greater in the elderly group (p <0.01), but the overall support area showed a decreasing trend. The CoP excursion in the media-lateral direction was significantly higher in the elderly group from double-leg stance to single-leg stance (p <0.01). The CoP trajectory in the elderly group tends to shift in a medial direction with increasing age or postural difficulty.

UNASSIGNED: To assess postural stability, specifically center of body sway during single-leg standing balance, among individuals with and without forward head posture (FHP) during smartphone use.
UNASSIGNED: The research recruited 53 healthy smartphone users, aged 18-25, and categorized them into FHP group comprising 26 subjects and the normal (control) group with 27 subjects. Participants were assigned the task of maintaining balance while engaged in smartphone typing during single-leg standing. The experiment involved four specific conditions according to neck posture and stable of surface. The study meticulously quantified body center of pressure (COP) sway amplitudes using the Nintendo Wii Balance Board.
UNASSIGNED: The research revealed that individuals with FHP exhibited significantly greater body sway compared to the control group when using smartphones. Notably, distinct variations were observed in path length sway, anteroposterior (AP), and mediolateral (ML) sway amplitude, particularly evident when maintaining flexed neck positions on a soft surface while engaged with smartphones.
UNASSIGNED: These findings strongly suggest that individuals with FHP encounter deteriorated postural stability during smartphone use, particularly in challenging head positions.

The mechanism by which postural threat induced by standing at a high height causes a decrease in the amplitude and an increase in the frequency of postural sway might involve voluntary control (VC) to avoid swaying, rather than conscious balance processing, in which postural threat directs conscious balance processing. This study aimed to clarify the differences between VC and conscious balance processing during quiet standing. Twenty-seven healthy young adults were instructed to stand with their feet placed together and keep their eyes open. The standing task was performed under three standing conditions: relaxed, VC, and high-conscious movement processing (high-CMP). The center of pressure in the anteroposterior (AP) and mediolateral (ML) directions was measured using a stabilometer to assess differences in postural control. The results indicated that the mean power frequency (MPF) ML and high frequency (HF) ML were higher in the VC condition than in the high-CMP condition. In the VC and high-CMP conditions, compared with the relaxed condition, MPF AP was higher, whereas the root mean square AP and low frequency AP were lower. These results show that the sway amplitude is lower, and the frequency is higher in both the VC and high-CMP conditions compared with those in the relaxed condition; however, the frequency is higher in the VC condition than in the high-CMP condition, suggesting that the VC condition is similar to postural control under the postural threat condition.

BACKGROUND: Postural control can be challenged by breathing.
OBJECTIVE: What is the effect of an acute increase in respiratory demand on postural control compared to quiet breathing?
METHODS: A systematic review was conducted. Electronic databases were systematically searched until October 18, 2022 on studies reporting changes in center of pressure (CoP) motion related to an acute manipulation of respiratory demand compared to quiet breathing during upright standing in healthy participants and/or participants with a clinical condition.
RESULTS: Twenty-one studies in healthy participants showed that voluntary (not metabolic-induced) hyperventilation or inspiratory resistive loading significantly increased CoP motion, while breath-holding decreased CoP motion, compared to quiet breathing (p< 0.05). Manipulating respiratory rate or breathing patterns did not reveal consistent results. Four studies showed that people with low back pain showed similar CoP responses to increasing respiratory demand (p> 0.05), except for breathing at different rates, whereas they showed greater CoP motion during quiet breathing.
CONCLUSIONS: The extent of postural disturbance depended on the breathing mode and how it was quantified (i.e., CoP coupled with breathing movement or overall CoP measures). Voluntary hyperventilation and inspiratory resistive loading increased postural sway. For voluntary hyperventilation, this could be explained by CoP motion being directly coupled to chest wall movements whereas metabolic-induced hyperventilation did not increase CoP motion or CoP coupling with breathing. Breath-holding decreased postural sway. Patients with low back pain show greater postural sways than pain-free individuals during quiet breathing, although they exhibit similar postural adaptations to respiratory-related challenges as controls.

This study was conducted to compare postural stability during repeated unilateral standing tasks between adults with and without chronic low back pain (LBP) while considering visual input. The study involved 26 participants with LBP and 39 control participants. Each participant performed three trials of standing tasks on the dominant limb using a stable platform. The Falls Efficacy Scale was utilized to assess fall-related self-efficacy and fear of falling due to potential physical frailty. The center of pressure (COP) sway excursion was analyzed at 10 mm and 20 mm thresholds for the time-in-boundary (TIB). The results indicated a significant fear of falling difference in the LBP group compared to the control group (t = 3.27, p = 0.001). The LBP group demonstrated a significant interaction between visual condition and TIB (F = 8.45, p = 0.01), particularly in the LBP group, which demonstrated a notable decrease in TIB at 10 mm (54.02 % compared to the control group\'s 70.40 %) and 20 mm (70.93 % compared to the control group\'s 85.92 %) thresholds during the second trial and at 10 mm (59.73 % compared to the control group\'s 73.84 %) during the third trial in the eyes open condition. Overall, visual condition demonstrated significant interactions on thresholds (F = 15.80, p = 0.001, η2p = 0.21) as well as trials  ×  thresholds (F = 4.21, p = 0.04, η2p = 0.07). These findings indicate a potential adaptation in postural control among the LBP group with visual feedback. Further research is warranted to explore group differences when considering visual conditions and sway excursion thresholds.