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This study aimed to examine muscle synergies involving the deeper muscles of the lower limb during level and uphill treadmill walking. Seven men and five women walked on a treadmill at three speeds (60, 80, and 100m/min) and two grades (level and 10% grade). Surface electromyographic (EMG) signals were recorded from 10 muscles of the lower limb, including vastus intermedius, adductor magnus, and adductor longus. Muscle synergies were extracted applying non-negative matrix factorization, and the relative co-activation across muscles and the temporal information of synergy recruitment were identified by the muscle synergy vector and synergy activation coefficient, respectively. Correlation coefficients between a pair of synergy vectors during level and uphill walking were analyzed as a similarity index, with the similarity criterion at r=0.76. Changes in synergy activation coefficients between the walking conditions were evaluated by cross-correlation analysis. The mean number of synergies ranged from 3.8 to 4.0 across all conditions, and they were not significantly different between level and uphill walking conditions. Similarity between walking conditions was high (r>0.76) for three muscle synergies, but not for one synergy that mainly consisted of the quadriceps femoris. The inter-condition similarity of the synergy activation coefficients was high for the four synergies, and a significant lag time for synergy 2, which consisted mainly of the activity of medial gastrocnemius, was found at 60 and 80m/min. The muscle synergies extracted from the lower limb involving the deeper muscles appear to be consistent during level and uphill treadmill walking. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of wearing high-heeled shoes (HHS) on gait variability of the lower limbs when the treadmill speed was sinusoidally changed. A total of 17 young females walked on a treadmill with HHS, HHS with detachable base sockets (HHS-Sockets), and low-heeled shoes (LHS) under sinusoidal speed-changing protocol of 60-s and 30-s periods with an amplitude of ± 0.56 m·s-1. The time course of the joint elevation angles of the thigh, shank, and foot in one gait cycle can be well approximated like a plan e in a triaxial space, so-called intersegmental coordination (IC). Standard deviation of the plane (IC thickness) was considered as the anteroposterior gait variability when the best-fitting plane of the angular covariation was obtained. The lateral gait variability was the coefficient of variance of step width (CV SW). To examine whether the gait parameters was associated with IC thickness, a sum of the time delay of the stride length and step frequency (TD SL+SF) against sinusoidal speed change was calculated. The IC thickness was not different across shoe conditions and periods. The CV SW was greater in the HHS and HHS-Sockets conditions than in the LHS condition. TD SL+SF was greater in the HHS condition than in the LHS and HHS-Sockets conditions at both periods; however, it was not correlated with IC thickness. Walking with HHS increased lateral gait variability at faster speed-changing situation, but not anteroposterior gait variability. Detachable sockets expanding the base area ten times greater than that of HHS could reduce TD SL+SF ; however, TD SL+SF could not explain the IC thickness. • Treadmill speed was sinusoidally changed at 30-s and 60-s periods. • Gait balance with high-heeled shoes was evaluated in speed changing conditions. • Wearing high-heeled shoes increased lateral gait variability. • High-heeled shoes did not influence anteroposterior gait variability. • Heel base area did not influence anteroposterior and lateral gait variability. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of wearing high-heeled shoes (HHS) on gait variability of the lower limbs when the treadmill speed was sinusoidally changed. A total of 17 young females walked on a treadmill with HHS, HHS with detachable base sockets (HHS-Sockets), and low-heeled shoes (LHS) under sinusoidal speed-changing protocol of 60-s and 30-s periods with an amplitude of ± 0.56 m·s-1. The time course of the joint elevation angles of the thigh, shank, and foot in one gait cycle can be well approximated like a plan e in a triaxial space, so-called intersegmental coordination (IC). Standard deviation of the plane (IC thickness) was considered as the anteroposterior gait variability when the best-fitting plane of the angular covariation was obtained. The lateral gait variability was the coefficient of variance of step width (CV SW). To examine whether the gait parameters was associated with IC thickness, a sum of the time delay of the stride length and step frequency (TD SL+SF) against sinusoidal speed change was calculated. The IC thickness was not different across shoe conditions and periods. The CV SW was greater in the HHS and HHS-Sockets conditions than in the LHS condition. TD SL+SF was greater in the HHS condition than in the LHS and HHS-Sockets conditions at both periods; however, it was not correlated with IC thickness. Walking with HHS increased lateral gait variability at faster speed-changing situation, but not anteroposterior gait variability. Detachable sockets expanding the base area ten times greater than that of HHS could reduce TD SL+SF ; however, TD SL+SF could not explain the IC thickness. • Treadmill speed was sinusoidally changed at 30-s and 60-s periods. • Gait balance with high-heeled shoes was evaluated in speed changing conditions. • Wearing high-heeled shoes increased lateral gait variability. • High-heeled shoes did not influence anteroposterior gait variability. • Heel base area did not influence anteroposterior and lateral gait variability. [ABSTRACT FROM AUTHOR]

This survey clarified foot pressure patterns and hindfoot deformities in individuals with advanced knee osteoarthritis (OA) and analyzed their associations with foot pain. Sixty-four individuals with unilateral knee OA who underwent total knee arthroplasty (TKA) were divided into the following groups: no foot pain (n=26; men:women, 4:22; mean age, 73.7 years), foot pain resolved after TKA (12; 2:10; 75.8), and foot pain remaining after TKA (26; 4:22; 74.7). Elderly individuals without pain or deformity in either knee (54; 10:44; 74.3) were controls. Navicular height ratio of the medial longitudinal arch, leg-heel angle, and partial foot pressure as the percentage of body weight (%PFP) were calculated.%PFPs of the medial and lateral heel regions before TKA were significantly lower for the no foot pain group than for controls. One year after TKA, %PFP improved significantly. In the foot pain resolved group, before TKA, the leg-heel angle was significantly higher, and%PFPs of the medial and lateral heel regions and navicular height ratio before TKA were significantly lower than those of controls. One year after TKA, all parameters improved significantly. In the foot pain remaining group, similar abnormalities were observed before TKA; however, significant improvement was only observed for%PFP of the medial heel region 1year after TKA. More than half of the patients with advanced knee OA had foot pain. This improved in approximately one-third, 1year after TKA. Hindfoot deformities are probably associated with foot pain in individuals with advanced knee OA. [ABSTRACT FROM AUTHOR]

The number of incidents related to walking while using smartphones is rising. However, it is not clear how smartphone usage might affect a gait pattern in terms of the foot pressure, and this may address the mechanism leading to incidents while using smartphones. How do the characteristics of walking while using a smartphone affect foot pressure patterns? In this cross-sectional study, we recruited 40 healthy young participants and investigated the walking speed, step length, coefficient of variance of the walking cycle (CV), anteroposterior length of the center of pressure (COP) trajectory (%Long), partial foot pressure ratios (% partial foot pressure [%PFP]), and COP existence time (COPexT) under the following four conditions: normal walking, screen gazing, while using social networking services (SNS), and while using a cognitive application. Parameters were compared among the four conditions using a repeated-measures ANOVA. Further, according to the presence or absence of an incident history (e.g. stumbles, collisions), participants were divided into either the incident or non-incident group. Parameters were compared between the two groups using a two-way repeated-measures ANOVA. Under the SNS and cognitive application conditions, the walking speed, step length, %Long, %PFP, and COPexT in the heel were significantly lower, and the CV and %PFP in the metatarsal region were higher than those under normal walking or screen gazing. %PFP in the heel and metatarsal regions showed a significant group-by-condition interaction; the incident group had lower %PFP in the heel region and higher %PFP in the metatarsal region than the non-incident group. These findings indicate a trend of loading more pressure on the forefoot than on the heel. This pattern was markedly evident in individuals with a history of incidents related to the smartphone usage and may be one of the factors causing stumbles and collisions. • Effects of smartphone use on walking parameters and foot pressure were examined. • Dual-task walking with smartphone use increases CV of walking cycle significantly. • Trend of disproportionate load pressure on the forefoot was observed. • Cognitive load was greater on those with prior experience of related incidents. [ABSTRACT FROM AUTHOR]

Background: Abnormal foot contact patterns following stroke affect functional gait; however, objective analysis targeting independent walking is lacking.Research Question: How do walking abilities and foot pressure patterns differ between post-stroke individuals who achieved independent walking and healthy controls? Secondarily, how do the abilities and patterns in post-stroke individuals change before and after achieving independent walking? Can these changes become criteria for permitting independent walking?Methods: Twenty-eight individuals with hemiplegia and 32 controls were enrolled. Motor dysfunction score (MDScore), walking speed (WSpeed), and foot pressure patterns were measured when they were first able to walk without orthosis or physical assistance (1st assessment) and when they achieved independent walking around discharge (2nd assessment). Foot pressure patterns were measured using insole-type foot pressure-measuring system. Ratios of partial foot pressure to body weight (%PFP), ratios of anteroposterior length of center of pressure (COP; %Long), and backward moving distance of COP to the foot length (%Backward) were calculated. Parameters during the 2nd assessment were compared with those of controls and those during the 1st assessment. During the 2nd assessment, relationships among the parameters, MDScore, and WSpeed were analyzed.Results: During the 2nd assessment, no difference was observed in both %Long and %Backward between the non-paretic limbs and the controls. While the %Backward was higher, the %PFP of toes and %Long were lower in the paretic limb than in the controls. Although the %Backward was lower, both %PFP of toes and %Long of the paretic limb were higher in the 2nd assessment than in the 1st assessment. During the 2nd assessment, both %Long and % Backward values of the paretic limb moderately correlated with MDScore and WSpeed.Significance: After improvement of foot pressure in toes, both an increase in anteroposterior length and a decrease in backward moving of COP path were objective signs permitting independent walking. [ABSTRACT FROM AUTHOR]