Sukwon Kim

Lower limb control and mobility following exercise training

The objective of the present study was to evaluate the effects of 8-week balance or weight training on ankle joint stiffness and limb stability for older adults, furthermore, on outcomes of slips while walking. Eighteen older adults volunteered for the study and randomly were assigned to the three groups, such as, weight, balance, or control group. While walking on a walking track, three-dimensional posture data were sampled and ankle joint stiffness and limb stability were computed to evaluate the effects of training. 2 (pre and post) × 3 (weight, balance, and control) × 2 (dominant and non-dominant legs) mixed factor repeated ANOVA was performed. The results indicated that only balance training group showed an improvement in joint stiffness and both the training groups showed improvements in limb stability. Also, fall frequency results suggested that joint stiffness and limb stability had an effect on the likelihood of slip-induced falls. In conclusion, training can facilitate improvements in joint and limb control mechanism for older adults contributing to an improvement in the likelihood of slip-induced falls.

Falls study: Proprioception, postural stability, and slips

The present study evaluated effects of exercise training on the proprioception sensitivity, postural stability, and the likelihood of slip-induced falls. Eighteen older adults (6 in balance, 6 in weight, and 6 in control groups) participated in this study. Three groups met three times per week over the course of eight weeks. Ankle and knee proprioception sensitivities and postural stability were measured. Slip-induced events were introduced for all participants before and after training. The results indicated that, overall, strength and postural stability were improved only in the training group, although proprioception sensitivity was improved in all groups. Training for older adults resulted in decreased likelihood of slip-induced falls. The study suggested that proprioception can be improved by simply being active, however, the results suggested that training would aid older adults in reducing the likelihood of slip-induced falls.

Asymmetrical slip propensity: required coefficient of friction

BackgroundMost studies in performing slips and falls research reported their results after the ipsilateral leg of subjects (either right foot or left foot) was guided to contact the contaminated floor surface although many studies indicated concerns for asymmetries of legs in kinematic or kinetic variables. Thus, the present study evaluated if dominant leg’s slip tendency would be different from non-dominant leg’s slip tendency by comparing the Required Coefficient of Friction (RCOF) of the two lower limbs.FindingsForty seven health adults participated in the present study. RCOF was measured when left or right foot of subjects contacted the force platforms respectively. Paired t-test was performed to test if RCOF and heel velocity (HCV) of dominant legs was different from that of non-dominant legs. It was suggested that the asymmetry in RCOFs and HCV between the two lower limbs existed. The RCOFs of non-dominant legs were higher than that of dominant legs.ConclusionsThe results indicated that asymmetry in slip propensity, RCOF, was existed in lower extremity. The results from the study suggested that it would be benefit to include a variable, such as asymmetry, in slips and falls research.

The effects of eight‐week balance training or weight training

The purpose of this study was to examine the influence of participating in an eight‐week physical training (ie. balance or weight training) on psychosocial outcomes for independently living healthy older adults. Eighteen older adults (65 years old or older) voluntarily participated in this study. Participants were randomly and evenly distributed in three different groups such as balance, weight or control group; six participants in each. Fear of falling and social activity levels were statistically tested by evaluating questionnaires validated in previous studies. Psychological factors improved in all groups after eight weeks (P < 0.05). Social interaction levels did not improve in any of the three groups, although all participants exhibited improvements in being physically independent (P < 0.05). Results suggested that being physically active as well as being socially active could result in being less fearful of falls, more confident of leaving residency, being more independent, and being more active.The purpose of this study was to examine the influence of participating in an 8-week physical training (ie: balance or weight training) on psychosocial outcomes for independently living healthy older adults. Eighteen older adults (65 years old or older) voluntarily participated for this study. Participants were randomly and evenly distributed in 3 different groups such as balance, weight, or control group; 6 participants each. Fear of falling and social activity levels were statistically tested by evaluating questionnaires validated in previous studies. Psychological factors improved in all groups after 8 weeks (P < 0.05). Social interaction level did not improve in any of the three groups, although all participants exhibited improvements in being physically independent (P < 0.05). Results suggested that being physically active as well as being socially active could result in being less fearful of falls, more confident of leaving residency, being more independent, and being more active.

Gait Asymmetry: Factors Influencing Slip Severity and Tendency among Older adults

Research on the relationship between gait asymmetry and the likelihood of slips are not clear, especially, for older adults. The present study evaluated the gait asymmetry among older adults and, further, evaluated effects of gait asymmetry on the likelihood of slips. Eighteen older adults (65 and older) participated in the study. HCV, horizontal force, and RCOF measured at non-dominant leg during heel contact phase of gait cycle were significantly higher than those at dominant leg. The results indicated that the likelihood of slips could increase when transitioning the whole body center-of-mass with left leg contacted on the ground while right leg was in swing phase. The results indicated that gait asymmetry or limb dominance could contribute to increasing the likelihood of slips.

Classification of Daily Activities for the Elderly Using Wearable Sensors

Monitoring of activities of daily living (ADL) using wearable sensors can provide an objective indication of the activity levels or restrictions experienced by patients or elderly. The current study presented a two-sensor ADL classification method designed and tested specifically with elderly subjects. Ten healthy elderly were involved in a laboratory testing with 6 types of daily activities. Two inertial measurement units were attached to the thigh and the trunk of each subject. The results indicated an overall rate of misdetection being 2.8%. The findings of the current study can be used as the first step towards a more comprehensive activity monitoring technology specifically designed for the aging population.

Assessment of Elderly`s Isokinetic Muscle Function, Flexibility and Balance in a Region of Seoul

The aim of the present study was to compare the strength, balance, and flexibility across two age groups (older adults vs. young adults). The isokinetic muscle function, ankle ROM, trunk forward flexibility, stability, and antropometric data for the elderly and 46 university students were collected. The results indicated that male older adults possessed relatively low flexibility (2.97cm) among the groups and showed better stability in the right foot than in the left foot and 35° of plantar flexion ROM, which was not in the normal range. Their peak strength at the knee joint was below 50% of their counterpart. They revealed a hamstring deficit of 18.55%, ankle eversion deficit of 23.08%, and ankle inversion deficit of 19.19%. The results indicated that female older adults possessed comparable flexibility compared to female young adults. The reciprocal muscle strength ratio of both knees was under 50%, and the deficit was 14.32% (extension) and 19.73% (flexion). The ankle plantar flexion peak torque was approximately 62% (left) and 73% (right) of WSs. The ankle dorsi flexion deficit was 25.05% and the plantar flexion was 26.86%. The eversion deficit was 19.97% and the inversion was 21.09%. These results will be significant in establishing an elderly fitness enhancement program and policy.

Reaction moment at the L5/S1 joint during simulated forward slipping with a handheld load.

The purpose of the study was to investigate the effects of load on the net moment response at the L5/S1 joint during simulated slip events. Six young individuals were instructed to take one step with a handheld load. Sudden floor movement was randomly introduced to simulate unexpected slips. Different loads conditions (0%, 10%, 20%, 30% of body weight) were introduced at random. Three-dimensional net moments at the L5/S1 joint were computed via downward inverse dynamic model. Peak joint moment generated at 30% load level was found to be significantly higher compared to no-load condition. No peak moment differences were found among no-load, 10% or 20% load levels. Additionally, the findings from this study indicated a flexiondominant net L5/S1 joint moment pattern during motion phase associated with slip-induced falls.

The Benefits of Stick Walking: Evaluation at Ankle, Knee and Hip Joints

A laboratory study was performed to evaluate the effects of an aid(i.e. stick) on joint loadings. Six healthy young participants were recruited from Virginia Tech student population. Each participant has performed three normal walking and three stick walking trials. Normalized and integrated, ground reaction forces(GRFs) and joint moments were measured at ankle, knee, and hip joints from kinematic and kinetic data. The result suggests that stick walking significantly reduces vertical ground reaction force and joint moments at ankle and knee compared to normal walking.

Effect of Whole Body Com Velocity on Friction Demand

The study was conducted to evaluate relationships among walking velocity, heel contact velocity, and friction demand. Particularly, the study attempted to ask if two age groups (younger and older groups) differed in walking velocity and heel contact velocity, and how these gait parameters influenced friction demand characteristics in two age groups. 14 younger (7 females and 7 males, 18 to 30 years old) and 14 older (7 females and 7 males, over 65 years old) adults participated in the study. Kinematic and kinetic data were measured using 6 infrared cameras and 2 force plates mounted on the walking track. The primary goal of the study was to evaluate if walking velocity (whole body COM velocity) and heel contact velocity with advancing age influenced friction demand characteristics. The results indicated that older adults walked slower, exhibited lower heel contact velocity, and produced lower friction demand in comparison to younger adults. The study suggested that walking velocity could be a good indicator for predicting friction demand characteristics.