Effect of Age and Sex on Gait Characteristics in the Korean Elderly People.

BACKGROUND: Incidence of falling in the older-elderly is higher than that of the younger-elderly. In addition, falls occur more in elderly women than in elderly men. However, it is unclear whether age and sex-specific differences exist in gait characteristics of the elderly. Therefore, the aim of this study was to investigate age- and sex-related differences in gait characteristics of the Korean elderly people. METHODS: A total of 75 younger-elderly subjects (age of 65-74 yr; 21 men and 54 women) and 59 older-elderly subjects (age of 75-90 yr; 15 men and 44 women) participated in this study in 2014. All participants walked a distance of 8 m across a GaitRite walkway with self-selected speed. The effects of age and sex on spatiotemporal gait variables in the Korean elderly people were analyzed before and after adjusting height as covariate. RESULTS: The older-elderly group slowly walked with shorter stride length (P<0.05) and step length (P<0.05) compared to the younger-elderly, regardless of their height. There was no significant sex difference after adjusting height as covariate, although elderly women walked with shorter stride length (P<0.01) and step length (P<0.01) than elderly men. The elderly women group walked with more variable stride time (P<0.05) and with longer double support (P<0.01). CONCLUSION: Age-related changes and sex difference among the elderly existed in specific gait variables. Characterizing gait patterns of the Korean elderly people considering both age and sex would be beneficial to assess gait of the elderly with risk of falls for fall interventions.

Comparison of gait patterns in elderly fallers and non-fallers.

Gait is associated with an important risk factor of falls in the elderly. It is important to find differences of quantitative gait variables between fallers and non-fallers. The aim of this study was to investigate gait patterns in elderly fallers and non-fallers. Thirty-eight fallers and 38 non-fallers of similar age and height participated in this study. Subjects walked across the GaitRite walkway at self-selected comfortable speeds. Spatio-temporal gait variables were measured to characterize gait patterns. Kinetic variables were derived from normalized vertical ground reaction force (GRF). Independent t-tests were performed to compare the fallers with the non-fallers. The fallers walked more slowly with shorter steps and more variable step times than the non-fallers (p< 0.05). The fallers showed a longer stance phase with increased double-limb support than the non-fallers (p< 0.05). The times to reach maximal weight acceptance and mid-stance of the fallers were significantly longer than those of the non-fallers (p< 0.05). These results suggest that spatio-temporal variables and GRF variables would be useful for distinguishing prospective fallers from non-fallers among the elderly.

Fatigue injury risk in anterior cruciate ligament of target side knee during golf swing.

A golf-related ACL injury can be linked with excessive golf play or practice because such over-use by repetitive golf swing motions can increase damage accumulation to the ACL bundles. In this study, joint angular rotations, forces, and moments, as well as the forces and strains on the ACL of the target-side knee joint, were investigated for ten professional golfers using the multi-body lower extremity model. The fatigue life of the ACL was also predicted by assuming the estimated ACL force as a cyclic load. The ACL force and strain reached their maximum values within a short time just after ball-impact in the follow-through phase. The smaller knee flexion, higher internal tibial rotation, increase of the joint compressive force and knee abduction moment in the follow-through phase were shown as to lead an increased ACL loading. The number of cycles to fatigue failure (fatigue life) in the ACL might be several thousands. It is suggested that the excessive training or practice of swing motion without enough rest may be one of factors to lead to damage or injury in the ACL by the fatigue failure. The present technology can provide fundamental information to understand and prevent the ACL injury for golf players.

Effects of core and non-dominant arm strength training on drive distance in elite golfers.

BACKGROUND: Various training schemes have sought to improve golf-related athletic ability. In the golf swing motion, the muscle strengths of the core and arms play important roles, where a difference typically exists in the power of arm muscles between the dominant and non-dominant sides. The purposes of this study were to determine the effects of exercises strengthening the core and non-dominant arm muscles of elite golf players (handicap < 3) on the increase in drive distance, and to present a corresponding training scheme aimed at improving golf performance ability. METHODS: Sixty elite golfers were randomized into the control group (CG, n = 20), core exercise group (CEG, n = 20), and group receiving a combination of muscle strengthening exercises of the non-dominant arm and the core (NCEG, n = 20). The 3 groups conducted the corresponding exercises for 8 weeks, after which the changes in drive distances and isokinetic strength were measured. RESULTS: Significant differences in the overall improvement of drive distance were observed among the groups (p < 0.001). Enhancement of the drive distance of NCEG was greater than both CG (p < 0.001) and CEG (p = 0.001). Except for trunk flexion, all variables of the measurements of isokinetic strength for NCEG also showed the highest values compared to the other groups. Examination of the correlation between drive distance and isokinetic strength revealed significant correlations of all variables except trunk flexion, wrist extension, and elbow extension. CONCLUSION: The combination of core and non-dominant arm strength exercises can provide a more effective specialized training program than core alone training for golfers to increase their drive distances.

Electromyography comparison of normal chair-desk system and assistant chair-desk system on fatigue.

[Purpose] This study was designed to test the effects of the Assistant Chair-Desk System (ACDS), which can reduce the forward tilt of the neck and trunk and the level of fatigue during long lasting study in the sitting position. [Subjects] Fourteen middle school students and 14 college students of mixed gender participated in this study. [Methods] Fatigue level, the trapezius muscle, and the forward tilt angle of the head and trunk as well as distance factors were assessed before after using a normal chair-desk system (NCDS) and the ACDS for 120 minutes. [Results] There was an interaction effect in the angle and length of the neck from the sitting posture changes after 2 hours of studying using the NCDS and ACDS. There were also significant differences in the fatigue levels, hip joint angles and the lengths from the head according to the main effects of the chair-systems. [Conclusion] The studying position while using the ACDS was determined to prevent significant fatigue levels of the muscle and body, provide support to the head, by limiting the forward movement of the neck, and prevent forward tilt of the neck and trunk, by enabling the target point and gaze to be closer to the horizontal direction.

Synergic effect of exercise and lipoic acid on protection against kainic acid induced seizure activity and oxidative stress in mice.

Anti-convulsant effects of physical exercise and lipoic acid (LA), also referred to as thioctic acid with antioxidant activity, were investigated using chemical induced seizure model. We investigated the synergic effect of physical exercise and LA on kainic acid-induced seizure activity caused by oxidative stress. After 8 weeks of swimming training, body weight decreased and endurance capacity increased significantly compared to sedentary mice. Kainic acid (30 mg/kg, i.p.) evoked seizure activity 5 min after injection, and seizure activity peaked approximately 80 min after kainic acid treatment. Median seizure activity score in KA only treated group was 4.55 (range 0.5-5), 3.45 for "LA + KA" group (range 0.5-4.3), 3.12 for "EX + KA" group (range 0.05-3.4, p < 0.05 vs. "KA only" group), 2.13 for "EX + LA + KA" group (range 0.5-3.0, p < 0.05 vs. "EX + KA" group). Also, there was a synergic cooperation of exercise and LA in lowering the mortality in kainic acid treated mice (χ2 = 5.45, p = 0.031; "EX + KA" group vs. "LA + EX + KA" group). In addition, the synergic effect of exercise and LA was found in PGx activity compared to separated treatment ("LA + EX + KA": 37.3 ± 1.36; p < 0.05 vs. "LA + KA" and "EX + KA" group). These results indicate that physical exercise along with LA could be a more efficient method for modulating seizure activity and oxidative stress.

Synthesis of multilayer graphene balls by carbon segregation from nickel nanoparticles.

Three-dimensional (3D) structured graphene is a material of great interest due to its diverse applications in electronics, catalytic electrodes, and sensors. However, the preparation of 3D structured graphene is still challenging. Here, we report the fabrication of multilayer graphene balls (GBs) by template-directed carbon segregation using nickel nanoparticles (Ni-NPs) as template materials. To maintain the ball shape of the template Ni-NPs, we used a carburization process using polyol solution as the carbon source and a thermal annealing process to synthesize graphene layers via carbon segregation on the outer surface of the Ni-NPs. The resulting GBs were hollow structures composed of multilayer graphene after the removal of core Ni-NPs, and the thickness of the graphene layers and the size of GBs were tunable by controlling the graphene synthesis conditions. X-ray diffraction analysis and in situ transmission electron microscope characterization revealed that carbon atoms diffused effectively into the Ni-NPs during the carburization step, and that the diffused carbon atoms in Ni-NPs segregated and successfully formed a graphene layer on the surface of the Ni-NPs during thermal annealing. We also performed further heat treatment at high temperature to improve the quality of the graphene layer, resulting in highly crystalline GBs. The unique hollow GBs synthesized here will be useful as excellent high-rate electrode materials for electrochemical lithium storage devices.

Si/Ge double-layered nanotube array as a lithium ion battery anode.

Problems related to tremendous volume changes associated with cycling and the low electron conductivity and ion diffusivity of Si represent major obstacles to its use in high-capacity anodes for lithium ion batteries. We have developed a group IVA based nanotube heterostructure array, consisting of a high-capacity Si inner layer and a highly conductive Ge outer layer, to yield both favorable mechanics and kinetics in battery applications. This type of Si/Ge double-layered nanotube array electrode exhibits improved electrochemical performances over the analogous homogeneous Si system, including stable capacity retention (85% after 50 cycles) and doubled capacity at a 3C rate. These results stem from reduced maximum hoop strain in the nanotubes, supported by theoretical mechanics modeling, and lowered activation energy barrier for Li diffusion. This electrode technology creates opportunities in the development of group IVA nanotube heterostructures for next generation lithium ion batteries.

The effects of target distance on pivot hip, trunk, pelvis, and kicking leg kinematics in Taekwondo roundhouse kicks.

The study purpose was to investigate the effects of target distance on pivot hip, trunk, pelvis, and kicking leg movements in Taekwondo roundhouse kick. Twelve male black-belt holders executed roundhouse kicks for three target distances (Normal, Short, and Long). Linear displacements of the pivot hip and orientation angles of the pelvis, trunk, right thigh, and right shank were obtained through a three-dimensional video motion analysis. Select displacements, distances, peak orientation angles, and angle ranges were compared among the conditions using one-way repeated measure ANOVA (p < 0.05). Several orientation angle variables (posterior tilt range, peak right-tilted position, peak right-rotated position, peak left-rotated position, and left rotation range of the pelvis; peak hyperextended position and peak right-flexed position of the trunk; peak flexed position, flexion range and peak internal-rotated position of the hip) as well as the linear displacements of the pivot hip and the reach significantly changed in response to different target distances. It was concluded that the adjustment to different target distances was mainly accomplished through the pivot hip displacements, hip flexion, and pelvis left rotation. Target distance mainly affected the reach control function of the pelvis and the linear balance function of the trunk.

Arrays of sealed silicon nanotubes as anodes for lithium ion batteries.

Silicon is a promising candidate for electrodes in lithium ion batteries due to its large theoretical energy density. Poor capacity retention, caused by pulverization of Si during cycling, frustrates its practical application. We have developed a nanostructured form of silicon, consisting of arrays of sealed, tubular geometries that is capable of accommodating large volume changes associated with lithiation in battery applications. Such electrodes exhibit high initial Coulombic efficiencies (i.e., >85%) and stable capacity-retention (>80% after 50 cycles), due to an unusual, underlying mechanics that is dominated by free surfaces. This physics is manifested by a strongly anisotropic expansion in which 400% volumetric increases are accomplished with only relatively small (<35%) changes in the axial dimension. These experimental results and associated theoretical mechanics models demonstrate the extent to which nanoscale engineering of electrode geometry can be used to advantage in the design of rechargeable batteries with highly reversible capacity and long-term cycle stability.