Yumi Higuchi

Knee adduction moment and medial knee contact force during gait in older people

External knee adduction moment has been studied as a surrogate for medial knee contact force. However, it is not known whether adduction moment is a rational measure for predicting medial knee contact force. The aim of this study was to investigate the correlation between knee adduction moment and medial knee contact force in older people, using musculo-skeletal simulation analysis. One hundred and twenty-two healthy older subjects participated in this study. Knee moment and medial knee contact force were calculated based on inverse dynamics analysis of normal walking. Muscle force and joint reaction force were used to determine the medial knee contact force during stance phase. The results showed that the maximum medial knee contact force was moderately correlated to the maximum knee adduction (r = 0.59) as well as the maximum extension moment (r = 0.60). The first peak of medial knee contact force had a significant strong correlation with the first peak of adduction moment and a moderate correlation with the maximum flexion moment. The second peak of medial knee contact force had a significant moderate correlation with both the second peak of adduction and the maximum extension moment. These results implied that the maximum adduction moment value could be used, to some extent, as a measure of the maximum medial knee contact force.

Dual-tasking over an extended walking distance is associated with falls among community-dwelling older adults

Aim Dual-task methods, in which walking is the primary task, are not sufficient for accurately screening for the risk of falls among healthy older adults. Therefore, the goal of this research was to investigate whether using a dual-task method over an extended walking distance can predict falls among community-dwelling older adults. Methods We enrolled independent community-dwelling adults aged ≥65 years. Physical performance, cognitive function, psychological function, and a dual-task test were assessed at baseline. Our dual-task test required the subjects to walk 60 m while stepping over lines. The intervals between the lines ranged from 50–100 cm and were unequal. Falls and fall-related injuries were measured over a 12-month follow-up period using monthly postal surveys. Results Ninety-two of 118 subjects (mean age, 75.4±5.5 years) completed the 12-month follow-up. Sixteen (17.4%) of fallers had injurious falls or fell more than or equal to two times. There were no significant differences between the fallers and non-fallers, except in age and in the number of missteps during the dual-task test when walking ≥40 m. The Kaplan–Meier analysis revealed that those who had more than one misstep while walking ≥40 m had a significantly higher incidence of injurious or multiple falls than those who had no missteps. Conclusion Our findings suggest that the dual-task method with an extended walking distance may be able to predict falls among community-dwelling older adults.

Quickness of trunk movements in a seated position, regardless of the direction, is more important to determine the mobility in the elderly than the range of the trunk movement

Although trunk function is known to be critical for maintaining balance during gait, a detailed evaluation regarding the relationship between trunk function and mobility has not been performed. We previously reported that the ability of quick lateral trunk movements in a seated position reflects mobility in elderly people. In this study, we further examined whether trunk movement in the anterior-posterior direction is also a determinant of mobility. In addition, the correlation between range of lateral trunk movement and mobility was also examined. One hundred and forty community-dwelling elderly participants (73.3±6.2 years) were enrolled in this study. We performed various trunk movement tests in a seated position, such as the seated side tapping test (SST), the seated anterior-posterior tapping test (APT), and the lateral sitting functional reach test (sitting reach test). Maximum gait speed and the timed up and go test (TUG) were performed to determine mobility. Parameters of trunk movement were compared. SST and APT showed moderate significant correlations with both maximum gate speed and TUG, while the sitting reach test weakly correlated (SST r=-0.58, p<0.01, APT r=-0.63, p<0.01, sitting reach test r=0.30, p<0.01). Moreover, multiple regression analysis revealed that SST and APT were independent indicators of both maximum gate speed and TUG, while the sitting reach test was not. These findings indicate that quickness, regardless of the direction of the movement, is more important than range in determining mobility in the elderly.

Kinetic Relationships between the Hip and Ankle Joints during Gait in Children with Cerebral Palsy: A Pilot Study.

[Purpose] The purpose of this study was to evaluate kinetic relationships between the ankle and hip joints during gait, in the late stance, in children with spastic cerebral palsy (CP). [Subjects] The subjects were 3 ambulant children with spastic hemiplegic CP (aged 10, 13, and 14: CP group) and 3 typically developing children with the same ages (control). [Methods] A three-dimensional gait analysis including force data was performed to compare the peak moment, power, and ankle/hip power ratio between the hemiplegic (uninvolved and hemiplegic) and the control groups. In the statistical analysis, mean values from 5 gait cycles for each of 3 conditions (uninvolved, hemiplegic and control) were used. The three conditions were compared by performing a Kruskal-Wallis test and Steel-Dwass multiple comparisons. [Results] The peak moments of ankle plantar flexors in the 10-year-old case, were significantly lower on the uninvolved and hemiplegic sides compared with the control group, respectively. The peak flexion moments of the hip on the hemiplegic side were significantly higher compared with the control in the 14- and 13-year-old cases. The peak of ankle power generation (A2) in the 13- and 10-year-old cases were significantly lower on the uninvolved and hemiplegic sides, respectively, compared with the control. The peaks of hip flexor power generation (H3) in the 14- and 13-year-old cases were significantly higher on the uninvolved and hemiplegic sides, respectively. The A2/H3 ratios were significantly lower on the uninvolved and hemiplegic sides compared with the control, and the ratio for the hemiplegic side was lower than that for the uninvolved side. [Conclusion] This study shows that propulsion of walking is generated by hip, rather than the ankle, on both the hemiplegic and involved sides.

Maximum movement velocity of the upper limbs reflects maximum gait speed in community-dwelling adults aged older than 60 years.

A number of studies have shown that the maximum movement velocity of the lower limbs is a critical determinant of gait speed in elderly adults. However, it is still unclear whether gait speed is associated with the movement velocity of the lower limbs or the movement velocity itself. Therefore, we measured the movement velocity of upper limbs that would not have a direct effect on gait, and examined the relationship between the movement velocity and gait speed.

Effect of Aging on Seated Stepping Variability

[Purpose] Accuracy in coordinating limb movements decreases with aging. The effect of aging on the variability of cyclic movements is not well known. The aim of this study was to examine the effect of aging on seated stepping variability. [Subjects and Methods] Twenty-six healthy young adults and 15 healthy elderly adults were instructed to walk at their preferred speed. Foot contact was monitored using reflective markers. Seated stepping was performed on force plates. The participants synchronized their stepping with 6 different metronome beats: 90–140 beats per minute (bpm). The time-series coefficient of variation (CV) was calculated. [Results] The cadence of young adults was 121 steps/min and that of the elderly adults was 125 steps/min in the elderly adults. The seated stepping CV decreased gradually from 90 to 120 bpm, but sharply increased at 130 and 140 bpm. Compared to young adults, the elderly adults had significantly higher CVs of seated stepping; however, the intergroup difference in the CV of seated stepping at 120 bpm was negligible. [Conclusions] Our results suggest that the stepping accuracy of the elderly is decreased; however, the rhythmic seated stepping accuracy does not decrease at the same rate as gait.

The association between intersegmental coordination in the lower limb and gait speed in elderly females

Human multi-segmental motion is a complex task requiring motor coordination. Uncoordinated motor control may contribute to the decline in mobility; however, it is unknown whether the age-related decline in intersegmental coordination relates to the decline in gait performance. The aim of this study was to clarify the association between intersegmental coordination and gait speed in elderly females. Gait measurements were performed in 91 community-dwelling elderly females over 60 years old. Foot, shank, and thigh sagittal motions were assessed. Intersegmental coordination was analyzed using the mean value of the continuous relative phase (mCRP) during four phases of the gait cycle to investigate phase differences in foot-shank and shank-thigh motions during a normal gait. The results showed that foot-shank mCRP at late stance had negative correlations with gait speed (r=-0.53) and cadence (r=-0.54) and a positive correlation with age (r=0.25). In contrast, shank-thigh mCRP at late stance had positive correlations with gait speed (r=0.37) and cadence (r=0.56). Moreover, partial correlation, controlling age, height, and weight, revealed that foot-shank mCRP at late stance had negative correlations with gait speed (r=-0.52) and cadence (r=-0.54). Shank-thigh mCRP at late stance had a positive correlation with gait speed (r=0.28) and cadence (r=0.51). These findings imply that the foot-shank and shank-thigh coordination patterns at late stance relate to gait speed, and uncoordinated lower limb motion is believed to be associated with the age-related decline in cadence.

CONTRIBUTION OF MUSCLE TENSION FORCE TO MEDIAL KNEE CONTACT FORCE AT FAST WALKING SPEED

Fast walking is considered as a factor that causes pain in patients suffering from knee disorders. This study examined the effect of walking speed on the medial knee contact force and identified contributions to the muscle tension on the medial knee contact force during fast walking using musculoskeletal simulation analysis. The muscle contribution to the medial knee contact force was calculated based on the joint angles and ground reaction force for the normal and fast walking experiments of seven subjects. The muscle force and joint reaction force were used to estimate the medial knee contact force. Results showed, in average, 70% increase in medial knee contact force at the first peak and 34% increase at the second peak with a fast walking speed, compared to when they walked at a normal walking speed. The remarkable increase in the first peak was mainly contributed by the increase in the quadriceps force resisting the external knee flexion moment. In contrast, the moderate increase of second peak was contributed by the increase in the gastrocnemius muscle force. These results suggest that the increase in medial knee contact force at fast walking speeds is caused by the increased muscle force.

Toe-Out Gait Decreases the Second Peak of the Medial Knee Contact Force

Toe-out angle alternation is a potential tactic for decreasing the knee adduction moment during walking. Published reports have not examined the medial knee contact force during the toe-out gait, although it is a factor affecting knee articular cartilage damage. This study investigated the effects of increased toe-out angle on the medial knee contact force, using musculoskeletal simulation analysis. For normal and toe-out gaits in 18 healthy subjects, the muscle tension forces were simulated based on the joint moments and ground reaction forces with optimization process. The medial knee contact force during stance phase was determined using the sum of the muscle force and joint reaction force components. The first and second peaks of the medial knee contact force were compared between the gaits. The toe-out gait showed a significant decrease in the medial knee contact force at the second peak, compared with the normal gait. In contrast, the medial knee contact forces at the first peak were not significantly different between the gaits. These results suggest that the toe-out gait is beneficial for decreasing the second peak of the medial knee contact force.

Plantarflexor training affects propulsive force generation during gait in children with spastic hemiplegic cerebral palsy: a pilot study

[Purpose] The purpose of this preliminary study was to assess the trade-off relationship between the hip and ankle joints after plantarflexor training in children with spastic hemiplegic cerebral palsy (CP). [Subjects and Methods] Three boys aged 9, 10, and 13 years with spastic hemiplegic CP participated in the study. Gait analysis was performed using a three-dimensional motion analysis device and a floor reaction force detection device before and after plantarflexor training. Data on gait speed and stride length for both sides were collected. Peak hip and ankle powers in the sagittal plane and ankle-to-hip power ratio (A2/H3 ratio) were calculated. Plantarflexor training comprised heel raises and exercise band resistance at the participant’s home (3 times/week for 12 weeks). [Results] The A2/H3 ratio increased significantly on both sides in two of three subjects after training. Peak A2 power increased significantly on both sides in subject 3 and on the affected side of subject 2. Peak H3 power decreased significantly on the non-affected side of subjects 1 and 2. [Conclusion] This study confirmed that two of three subjects demonstrated a trade-off relationship between the hip and ankle joints during gait after plantarflexor training.