Maximum step length: relationships to age and knee and hip extensor capacities

Relationship between respiratory muscle strength and dynamic balance in older persons requiring care or support: Focusing on the maximal single step length test and maximal double step length test as dynamic balance indices

BACKGROUND

Falls are a major health problem. The relationship between dynamic balance related to falls and respiratory muscle strength related to sarcopenia and frailty is poorly understood.

RESEARCH QUESTION

How do dynamic balance measures, such as maximal single step length test (MSL) and maximal double step length test (MDST), and respiratory muscle strength measures, such as maximal inspiratory (PImax) and maximal expiratory (PEmax), related to the requirement for long-term care or support in older people who live in the community?

METHODS

This was a cross-sectional study of 39 older people (17 men, 22 women) aged ≥ 65 years community-dwelling who were certified as requiring long-term care or support under the Japanese system. The participants' PImax, PEmax, MSL, and MDST results were recorded. The measurement data were evaluated using Pearson's correlation coefficients and multiple regression analysis.

RESULTS

MDST showed a positive correlation with PImax (r = 0.430, p = 0.006) but no correlation with PEmax. MSL showed no correlation with PImax or PEmax. A positive correlation was found between MDST and MSL (r = 0.851, p < 0.001), and multiple regression analysis with MDST as the dependent variable and PImax and MST as independent variables showed significant differences for MSL (p < 0.001) and PImax (p = 0.027).

SIGNIFICANCE

In older people requiring long-term care or support, MDST had a greater association with inspiratory muscle strength compared with MSL. These results suggest the importance of inspiratory muscle strength training and MDST assessment in the prevention of falls in older people requiring long-term care or support.

Guided Exploration Leads to Faster Familiarization with a Wearable Robot: First Results of an Innovative Protocol

Wearable robots show promise in addressing physical and functional deficits in individuals with mobility impairments. However, the process of learning to use these devices can take a long time. In this study, we propose a novel protocol to support the familiarization process with a wearable robot (the Myosuit) and achieve faster walking speeds. The protocol involves applying an anterior pulling force while participants perform a series of 10-meter Walking Tests (10mWT) with or without the Myosuit under various experimental conditions. We hypothesized that guiding the exploration of novel walking patterns can help the users learn to exploit the Myosuit's assistance faster by leading to larger step lengths and ultimately higher walking speeds. In this paper, we present the preliminary results of the protocol with seven participants with lower-limb mobility impairments. Participants who were assisted by the Myosuit showed a continuous increase in walking speed over the course of the pulling part of the experiment with a maximum increase of 41.3% (10.4%) when compared to the baseline 10mWT. Following the removal of the pulling force, these participants continued to show an increased walking speed while being supported by the Myosuit. This higher walking speed was primarily due to a significant increase in step length of 24% (16.6%) and cadence of 11% (8.9%). The results of this study may help the development of familiarization techniques for wearable robots.

Effects of personal protective clothing on firefighters' gait analyzed using 3D motion capture system

OBJECTIVES

The effects of personal protective clothing (PPC) on firefighters' gait were investigated to develop high-performance PPC.

METHODS

Thirteen participants participated in human trials with three types of PPC (firefighter protective clothing (FPC); semi-enclosed chemical protective clothing (CPC_semi); full-enclosed chemical protective clothing (CPC_full)) and T-shirt (CON). A 3D motion capture system was used to obtain gait parameters (step length, step width, stride frequency, gait speed, and toe-out angle) and the range of motion (ROM) of the joints (hip, knee, and ankle).

RESULTS

PPCs produced an increase in step width (23.4%, p > 0.05), but the gait speed (9.1%) and stride frequency (6.4%) decreased compared with the CON results. ROM is affected by the PPC type and joint. FPC and CPC_semi had no significant effect in terms of the ROM of the hip and knee besides the landing angle of the knee. However, CPC_full had a significant effect on the maximum extension angle of the hip and maximum flexion angle of the knee, which reached up to 27.2%.

CONCLUSION

The ROM of the firefighter's lower limbs were limited by PPC. This study offers insights into next-generation PPC design and development, as well as guidelines for training and firefighting.

The Effects of a Divided-Attention Timed Stepping Accuracy Task on Balance, Strength, Endurance, and Functional Performance in Healthy Older Adults: A Pilot Study

The aim of this study was to investigate whether a 6-week Divided-Attention Stepping Accuracy Task (DATSAT) intervention improved the primary outcome measure, maximal step length; other balance measures (Berg Balance scale and Timed Up and Go test); leg strength; endurance (6-min walk test); and functional tasks in 15 community-dwelling healthy older adults ( x¯ age: 71.5 years, female: 46.7%) compared with 15 community-dwelling healthy older adults in a Bike and Strength (B&S) program ( x¯ age: 73.8 years, female: 33.3%). Participants trained 3× per week, 30-60 min per session. Stepping-group differences were significant for all measures. B&S group improved in maximal step length (anterior and lateral), strength, and one functional task. Stepping group outperformed B&S group in Timed Up and Go and maximal step length posterior. B&S group outperformed stepping group in two strength measures. Exertion scores were lower for the stepping group. Overall, Divided-Attention Timed Stepping Accuracy Task training resulted in more within-group improvements and two between-group measures with less perceived effort and shorter intervention times.

Reliability of the Maximal Step Length Test and Its Correlation with Motor Function in Chronic Stroke Survivors

OBJECTIVE

This study aimed to (1) investigate the interrater, intrarater, and test-retest reliabilities, as well as the minimal detectable change, of the Maximal Step Length test (MSL) in stroke survivors, (2) examine the concurrent validity of MSL with other stroke-specific impairment measurements in stroke survivors, and (3) compare the MSL performances of stroke survivors and those of age-matched healthy older adults in different directions.

DESIGN

Cross-sessional study.

SETTING

University-based research laboratory.

PARTICIPANTS

Stroke survivors (n = 48) and age-matched healthy older adults (n = 39).

METHODS

Stroke survivors were assessed with MSL, lower limb muscle strength, Limits of Stability (LOS) Test, Berg Balance Scale (BBS), 5-meter walk test, and Activities-specific Balance Confidence (ABC) scale by two trained assessors in 1 session. Their performance on MSL was reassessed 1 week later to establish the test-retest reliability. Healthy older adults were assessed with MSL only. Intraclass correlation coefficient (ICC) was used to assess the reliability of MSL and Spearman's rho was used to quantify the strength of correlations between MSL and secondary outcomes. Between-group differences of MSL were assessed with the independent t-test.

RESULTS

The MSL exhibited excellent intrarater, interrater, and test-retest reliabilities [ICC: 0.885-1.000]. Significant correlations (ρ: 0.447-0.723) were demonstrated between MSLs in most directions and muscle strengths of the affected legs, BBS scores, and walking speeds. The step lengths differed significantly between stroke survivors and healthy older adults in the forward, backward, and sideways directions on both the affected and less affected sides.

CONCLUSIONS

The MSL is a reliable, valid, and easily administered test of the stepping capabilities of stroke survivors. Stroke survivors had significant shorter MSLs in all directions than the age-matched healthy older adults.

The association between the maximum step length test and the walking efficiency in children with cerebral palsy

[Purpose] To improve walking efficiency could be useful for reducing fatigue and extending possible period of walking in children with cerebral palsy (CP). For this purpose, current study compared conventional parameters of gross motor performance, step length, and cadence in the evaluation of walking efficiency in children with CP. [Subjects and Methods] Thirty-one children with CP (21 boys, 10 girls; mean age, 12.3 ± 2.7 years) participated. Parameters of gross motor performance, including the maximum step length (MSL), maximum side step length, step number, lateral step up number, and single leg standing time, were measured in both dominant and non-dominant sides. Spatio-temporal parameters of walking, including speed, step length, and cadence, were calculated. Total heart beat index (THBI), a parameter of walking efficiency, was also calculated from heartbeats and walking distance in 10 minutes of walking. To analyze the relationships between these parameters and the THBI, the coefficients of determination were calculated using stepwise analysis. [Results] The MSL of the dominant side best accounted for the THBI (R²=0.759). [Conclusion] The MSL of the dominant side was the best explanatory parameter for walking efficiency in children with CP.

Effects of age and step length on joint kinetics during stepping task

Following a balance perturbation, a stepping response is commonly used to regain support, and the distance of the recovery step can vary. To date, no other studies have examined joint kinetics in young and old adults during increasing step distances, when participants are required to bring their rear foot forward. Therefore, the purpose of this study was to examine age-related differences in joint kinetics with increasing step distance. Twenty young and 20 old adults completed the study. Participants completed a step starting from double support, at an initial distance equal to the individual's average step length. The distance was increased by 10% body height until an unsuccessful attempt. A one-way, repeated measures ANOVA was used to determine the effects of age on joint kinetics during the maximum step distance. A two-way, repeated measures, mixed model ANOVA was used to determine the effects of age, step distance, and their interaction on joint kinetics during the first three step distances for all participants. Young adults completed a significantly longer step than old adults. During the maximum step, in general, kinetic measures were greater in the young than in the old. As step distance increased, all but one kinetic measure increased for both young and old adults. This study has shown the ability to discriminate between young and old adults, and could potentially be used in the future to distinguish between fallers and non-fallers.

Effects of step length, age, and fall history on hip and knee kinetics and knee co-contraction during the maximum step length test

BACKGROUND

Maximum step length is a brief clinical test involving stepping out and back as far as possible with the arms folded across the chest. This test has been shown to predict fall risk, but the biomechanics of this test are not fully understood. Knee and hip kinetics (moments and powers) are greater for longer steps and for younger subjects, but younger subjects also step farther.

METHODS

To separate the effects of step length, age, and fall history on joint kinetics; healthy younger (age=27(5), N=14), older non-fallers (age=72(5), N=14), and older fallers (age=75(6), N=11) all stepped to the same relative target distances of 20-80% of their height. Knee and hip kinetics and knee co-contraction were calculated.

FINDINGS

Hip and knee kinetics and knee co-contraction all increased with step length, but older non-fallers and fallers utilized greater stepping hip and less stepping knee extensor kinetics. Fallers had greater stepping knee co-contraction than non-fallers. Stance knee co-contraction of non-fallers was similar to young for shorter steps and similar to fallers for longer steps.

INTERPRETATION

Age had minimal effects and fall history had no effects on joint kinetics of steps to similar distances. Effects of age and fall history on knee co-contraction may contribute to age-related kinetic differences and shorter maximal step lengths of older non-fallers and fallers, but step length correlated with every variable tested. Thus, declines in maximum step length could indicate declines in hip and knee extensor kinetics and impaired performance on similar tasks like recovering from a trip.

Moving with ease: feldenkrais method classes for people with osteoarthritis

Objective. To investigate the effects of Feldenkrais Method classes on gait, balance, function, and pain in people with osteoarthritis. Design. Prospective study with pre-/postmeasures. Setting. Community. Participants. Convenience sample of 15 community-dwelling adults with osteoarthritis (mean age 67 years) attending Feldenkrais Method classes. Intervention. Series of Feldenkrais Method classes, two classes/week for 30 weeks.

MAIN OUTCOME MEASURES

Western Ontario and McMaster Universities osteoarthritis scale, Human Activity Profile, stair climbing test, 6-minute walk test, timed up-and-go test, Four Square Step Test (4SST), gait analysis, and assessment of quality of life (AQoL). Results. Participants improved on the 4SST and on some gait parameters. They also reported a greater ease of movement. Conclusions. A 30-week series of Feldenkrais classes held twice per week was feasible in the community setting. The lessons led to improvements in performance of the four square step test and changes in gait.

Lower-extremity force decrements identify early mobility decline among community-dwelling older adults

BACKGROUND

Many apparently independent older adults modify daily tasks. Task modifications strongly predict future mobility disability. Clinically intuitive, easily measured "biomarkers" associated with task modifications would offer quantifiable treatment targets for prevention of age-related functional limitations.

OBJECTIVE

The objective of the study was to examine lower-extremity muscle strength deficits and functionally relevant cutoff points associated with daily task modifications in community dwelling older adults living independently.

DESIGN

This was a cross-sectional observational study.

METHODS

Fifty-three participants (mean age=76.4 years, SD=5.2) were tested for task modifications and leg strength. Task modifications were assessed using a previously described tool (summary task modification score). Twenty-six of the participants were classified as task modifiers (TM group), and 27 participants were classified as non-task modifiers (NTM group). A net antigravity leg force in the sagittal plane (NETforce) was calculated by summing the normalized isometric and isokinetic torques from the hip extensors, knee extensors, and ankle plantar flexors.

RESULTS

Compared with the NTM group, the TM group exhibited 30.0% and 33.5% reduction in lower-extremity isometric and isokinetic NETforces, respectively. Isometric and isokinetic NETforce cutoff points for task modifications were ≤ 4.24 and 2.77 N · m/kg body weight, respectively. The isometric and isokinetic models both yielded sensitivity and specificity values of 74.1% and 80.8%, respectively (positive likelihood ratio=3.852, 95% confidence interval=1.699-8.735; negative likelihood ratio=0.321, 95% confidence interval=0.167-0.618). Isometric and isokinetic NETforces were significantly associated with task modifications (odds ratio=2.50 and 2.42, respectively).

LIMITATIONS

The cross-sectional design of this study does not allow for a test of causal relationships. This study used a modest yet adequate sample size that may limit generalization of the results.

CONCLUSIONS

Isometric and isokinetic NETforce cutoff points provide quantifiable biomarkers that discriminate community-dwelling older adults who modify daily tasks from those who do not.

The maximal double step length test can evaluate more adequately the decrease of physical function with age, than the maximal single step length test

The maximal double step length (MDSL) test is a modified version of the maximal step length (MSL) test used to evaluate the dynamic balance related to falls in the elderly. Although this test can evaluate their physical function using movements similar to daily activities as compared to MSL, it has not been clarified whether it can adequately evaluate the activities of daily living (ADL) abilities of the elderly, as they decrease with age. This study aimed to examine the relationship between both MSL and MDSL on age and ADL in elderly subjects. Fifty-seven elderly females who live independently (age 74.8±5.6 years) were recruited. MSL and MDSL were conducted twice after completing an ADL questionnaire. Intra-class correlation coefficients (ICCs) of both tests were high (for MSL: ICC=0.95, for MDSL: ICC=0.81-0.82). Age and ADL significantly correlated to MDSL (age: r=-0.32-0.41, ADL: r=0.28-0.48), but not to MSL (age: r=-0.19, ADL: r=0.15). MDSL has high reliability as it relates to age and ADL. It may be more useful to evaluate ADL required for independent living and prevent falls in the elderly better than MSL.

Can hip and knee kinematics be improved by eliminating thigh markers?

BACKGROUND

Marker sets developed for gait analysis are often applied to more dynamic tasks with little or no validation, despite known complications of soft tissue artifact.

METHODS

This study presents a comparison of hip and knee kinematics as calculated by five concurrently-worn tracking marker sets during eight different tasks. The first three marker sets were based on Helen Hayes but used (1) proximal thigh wands, (2) distal thigh wands, and (3) patellar markers instead of thigh wands. The remaining two marker sets used rigid clusters on the (4) thighs and shanks and (5) only shanks. Pelvis and foot segments were shared by all marker sets. The first three tasks were maximal femoral rotations using different knee and hip positions to quantify the ability of each marker set to capture this motion. The remaining five tasks were walking, walking a 1m radius circle, running, jumping, and lunging.

FINDINGS

In general, few and small differences in knee and hip flexion-extension were observed between marker sets, while many and large differences in adduction-abduction and external-internal rotations were observed. The shank-only tracking marker set was capable of detecting the greatest hip external-internal rotation, yet only did so during dynamic tasks where greater hip axial motions would be expected. All data are available in the Appendix.

INTERPRETATION

Marker set selection is critical to non-sagittal hip and knee motions. The shank-only tracking marker set presented here is a viable alternative that may improve knee and hip kinematics by eliminating errors from thigh soft tissue artifact.

Decreased muscle strength relates to self-reported stooping, crouching, or kneeling difficulty in older adults

BACKGROUND

Bending down and kneeling are fundamental tasks of daily living, yet nearly a quarter of older adults report having difficulty performing or being unable to perform these movements. Older adults with stooping, crouching, or kneeling (SCK) difficulty have demonstrated an increased fall risk. Strength (force-generating capacity) measures may be useful for determining both SCK difficulty and fall risk.

OBJECTIVE

The purposes of this study were: (1) to examine muscle strength differences in older adults with and without SCK difficulty and (2) to examine the relative contributions of trunk and leg muscle strength to SCK difficulty.

DESIGN

This was a cross-sectional observational study.

METHODS

Community-dwelling older adults (age [X+/-SD]=75.5+/-6.0 years) with SCK difficulty (n=27) or without SCK difficulty (n=21) were tested for leg and trunk strength and functional mobility. Isometric strength at the trunk, hip, knee, and ankle also was normalized by body weight and height.

RESULTS

Compared with older adults with no SCK difficulty, those with SCK difficulty had significant decreases in normalized trunk extensor, knee extensor, and ankle dorsiflexor and plantar-flexor strength. In 2 separate multivariate analyses, raw ankle plantar-flexor strength (odds ratio [OR]=0.97, 95% confidence interval [CI]=0.95-0.99) and normalized knee extensor strength (OR=0.61, 95% CI=0.44-0.82) were significantly associated with SCK difficulty. Stooping, crouching, and kneeling difficulty also correlated with measures of functional balance and falls.

LIMITATIONS

Although muscle groups that were key to rising from SCK were examined, there are other muscle groups that may contribute to safe SCK performance.

CONCLUSIONS

Decreased muscle strength, particularly when normalized for body size, predicts SCK difficulty. These data emphasize the importance of strength measurement at multiple levels in predicting self-reported functional impairment.

The effects of age and step length on joint kinematics and kinetics of large out-and-back steps

BACKGROUND

Maximum step length (MSL) is a clinical test that has been shown to correlate with age, various measures of fall risk, and knee and hip joint extension speed, strength, and power capacities, but little is known about the kinematics and kinetics of the large out-and-back step utilized.

METHODS

Body motions and ground reaction forces were recorded for 11 unimpaired younger and 10 older women while attaining maximum step length. Joint kinematics and kinetics were calculated using inverse dynamics. The effects of age group and step length on the biomechanics of these large out-and-back steps were determined.

FINDINGS

Maximum step length was 40% greater in the younger than in the older women (P<0.0001). Peak knee and hip, but not ankle, angle, velocity, moment, and power were generally greater for younger women and longer steps. After controlling for age group, step length generally explained significant additional variance in hip and torso kinematics and kinetics (incremental R2=0.09-0.37). The young reached their peak knee extension moment immediately after landing of the step out, while the old reached their peak knee extension moment just before the return step liftoff (P=0.03).

INTERPRETATION

Maximum step length is strongly associated with hip kinematics and kinetics. Delays in peak knee extension moment that appear to be unrelated to step length, may indicate a reduced ability of older women to rapidly apply force to the ground with the stepping leg and thus arrest the momentum of a fall.