Minimal power required to ascend a flight of stairs versus actual power measured with body-fixed sensors in adults aged 19-85 years

A good stair-climbing (SC) ability is crucial for independent living in older adults. A simple formula that estimates the mean power needed to ascend a flight of stairs in a predetermined time (i.e., total ascent duration) is easy to implement in practice, but lacks information on actual power values generated per step. The latter is possible with body-fixed sensors. This study aimed at comparing both methodologies and investigating their sensitivity to detect age-related differences. 318 participants (162 ♀; age 19-85 years) were tested on a 6-step staircase and two methodologies were used to estimate mean SC power: (1) a body-fixed sensor with automated detection of power production per step, and (2) a mathematic equation based on timed ascent duration, body mass and stair height. SC power was 210.4 W lower with formula compared to sensor, lower in women versus men and in older versus young adults (p < 0.001). The difference in SC power between sensor and formula was greater in individuals with better performance (i.e., men and young adults) (p < 0.001), indicating a ceiling effect of the formula in well-functioning and younger individuals. Likewise, ICC's between both methodologies showed poor reliability in people aged <65 years (0.087-0.363) and moderate to good reliability in people aged ≥65 years (0.453-0.780). To conclude, participants with better SC performance are able to largely overshoot the minimal power required to ascend the stairs in a certain duration. This makes the sensor more sensitive to identify early age-related differences compared to the formula.

Older adults' lower-limb muscle power production throughout a full flight of stairs: Reliability and comparison between different stair models

Lower-limb muscle power should be closely monitored to prevent age-related functional ability declines. Stair-climbing (SC) power is a functionally relevant measurement of lower-limb muscle power. Body-fixed sensors can measure power production throughout the different steps of a flight of stairs to assess different aspects of performance. This study investigated: 1) power production throughout a full flight of stairs; 2) if staircases with less or more steps can provide similar information; and 3) test-retest reliability of SC power. 116 community-dwelling older adults (57 women) ascended three staircases as fast as possible: 12, 6 and 3 steps. Mean vertical power production per step was collected and analyzed using a commercial body-fixed sensor and software. Three phases were found in SC power production: 1) an acceleration phase, i.e., the power produced in step 1 (P1); 2) a phase where the highest performance (Pmax) is reached and; 3) a fatiguing phase with power loss (Ploss; only measurable on 12-step staircase). Mean power (Pmean) over the different steps was also evaluated. P1 did not differ between staircases (all p>0.05), whereas Pmax and Pmean were higher with increasing number of steps (p = 0.073 -p<0.001). P1, Pmax and Pmean were strongly correlated between staircases (r = 0.71-0.95, p<0.05). and showed good to excellent reliability (ICC = 0.66-0.95, p<0.05). Ploss showed poor reliability. To conclude, measurements of SC power production (P1, Pmax and Pmean) with a single sensor on the lower back are reliable across different staircases. A small, transportable, 3-step staircase can be used for measuring power production in clinical practices with no access to regular staircases. However, absolute values are dependent on the number of steps, indicating that measurements to track performance changes over time should always be done using an identical stair model.

Greater number of weekly stairs climbed is associated with lower low back pain prevalence among female but not male physical therapists

INTRODUCTION

Certain cardiovascular health benefits of stair climbing are now widely accepted, but no prior studies have as yet been found linking the quantity of stairs climbed to low back pain (LBP) morbidity. Low back pain is a common musculoskeletal impairment, and research has begun to show an association between LBP and gluteus maximus (GM) weakness. With stair climbing being the activity which most activates GM, the aim of the present research was to assess the relationship between stair ambulation and LBP prevalence. The hypothesis of this cross-sectional study was that individuals with LBP would report a significantly lower numbers of stair flights climbed compared with individuals without LBP.

METHODS

A survey tool was developed and distributed via email to a convenience sample of orthopedic physical therapists. Survey items included information regarding medical history, physical activity, workplace, and LBP factors, using a one-year prevalence period.

RESULTS

A total of 363 respondents took the survey and, after application of exclusion criteria, 248 records remained in our final sample. When analyzing all genders together, non LBP (NLBP) respondents reported a mean of 51.62 flights climbed per week; and LBP respondents reported 37.82 flights climbed per week, with P = 0.077. When males and females were analyzed separately, a statistically significant difference in mean number of flights of stairs climbed was found among female respondents (61.51 flights climbed for NLBP and 35.61 flights climbed for LBP females; P = 0.031). When analyzed based on chronicity of LBP, an even stronger association between stairs climbed and LBP prevalence was found for female respondents with acute LBP (P = 0.009).

CONCLUSIONS

More weekly stairs climbed was associated with a lower LBP prevalence among females, especially with respect to acute LBP. Randomized, longitudinal research is, however, required to confirm a relationship between stair climbing and LBP.

Investigation with able-bodied subjects suggests Myosuit may potentially serve as a stair ascent training robot

Real world settings are seldomly just composed of level surfaces and stairs are frequently encountered in daily life. Unfortunately, ~ 90% of the elderly population use some sort of compensation pattern in order to negotiate stairs. Because the biomechanics required to successfully ascend stairs is significantly different from level walking, an independent training protocol is warranted. Here, we present as a preliminary investigation with 11 able-bodied subjects, prior to clinical trials, whether Myosuit could potentially serve as a stair ascent training robot. Myosuit is a soft wearable exosuit that was designed to assist the user via hip and knee extension during the early stance phase. We hypothesized that clinical studies could be carried out if the lower limb kinematics, sensory feedback via plantar force, and electromyography (EMG) patterns do not deviate from the user's physiological stair ascent patterns while reducing hip and knee extensor demand. Our results suggest that Myosuit conserves the user's physiological kinematic and plantar force patterns. Moreover, we observe approximately 20% and 30% decrease in gluteus maximus and vastus medialis EMG levels in the pull up phase, respectively. Collectively, Myosuit reduces the hip and knee extensor demand during stair ascent without any introduction of significant compensation patterns.

There are unique kinematics during locomotor transitions between level ground and stair ambulation that persist with increasing stair grade

Human ambulation is typically characterized during steady-state isolated tasks (e.g., walking, running, stair ambulation). However, general human locomotion comprises continuous adaptation to the varied terrains encountered during activities of daily life. To fill an important gap in knowledge that may lead to improved therapeutic and device interventions for mobility-impaired individuals, it is vital to identify how the mechanics of individuals change as they transition between different ambulatory tasks, and as they encounter terrains of differing severity. In this work, we study lower-limb joint kinematics during the transitions between level walking and stair ascent and descent over a range of stair inclination angles. Using statistical parametric mapping, we identify where and when the kinematics of transitions are unique from the adjacent steady-state tasks. Results show unique transition kinematics primarily in the swing phase, which are sensitive to stair inclination. We also train Gaussian process regression models for each joint to predict joint angles given the gait phase, stair inclination, and ambulation context (transition type, ascent/descent), demonstrating a mathematical modeling approach that successfully incorporates terrain transitions and severity. The results of this work further our understanding of transitory human biomechanics and motivate the incorporation of transition-specific control models into mobility-assistive technology.

Effects of McConnell and Kinesio taping on kinematic variables during stair descent in patients with patellofemoral pain syndrome

BACKGROUND

Studies regarding effects of therapeutic tapings when patients with patellofemoral pain syndrome (PFPS) descend stairs are limited.

OBJECTIVE

The purpose of this study was to investigate the effect of McConnell taping (MT) and Kinesio taping (KT) on kinematic variables when patients with PFPS descend stairs.

METHODS

Fifty PFPS patients were randomly assigned to either the MT group or the KT group. Pain and lower extremities joint angles were measured while descending stairs before and after the intervention. All outcomes measured were analyzed using either paired t tests or independent t tests to compare the difference within or between groups, respectively.

RESULTS

There was a statistically significant difference in both groups in anterior knee pain scale score (p< 0.05). As a result of analysis of lower extremities joint angles at initial contact, loading response, and terminal stance, there were statistically significant within-group differences in hip, knee flexion, abduction and lateral rotation angles in both groups (p< 0.05). There were statistically significant within-group differences in hip flexion, knee flexion, and dorsiflexion angles in pre-swing (p< 0.05). There was a statistically significant difference between the groups in the following events: (1) knee lateral rotation angle at initial contact; (2) hip flexion angle at loading response; (3) and hip flexion at terminal stance angle (p< 0.05).

CONCLUSION

MT and KT were effective in lowering knee pain and improving lower extremities joint angle when patients with PFPS descend stairs. In the comparison between the groups, the MT group showed significantly reduced anterior knee pain and increased range of motion of the lower extremities joint compared to the KT group.

Muscle function during single leg landing

Landing manoeuvres are an integral task for humans, especially in the context of sporting activities. Such tasks often involve landing on one leg which requires the coordination of multiple muscles in order to effectively dissipate kinetic energy. However, no prior studies have provided a detailed description of the strategy used by the major lower limb muscles to perform single-leg landing. The purpose of the present study was to understand how humans coordinate their lower limb muscles during a single-leg landing task. Marker trajectories, ground reaction forces (GRFs), and surface electromyography (EMG) data were collected from healthy male participants performing a single-leg landing from a height of 0.31 m. An EMG-informed neuromusculoskeletal modelling approach was used to generate neuromechanical simulations of the single-leg landing task. The muscular strategy was determined by computing the magnitude and temporal characteristics of musculotendon forces and energetics. Muscle function was determined by computing muscle contributions to lower limb net joint moments, GRFs and lower limb joint contact forces. It was found that the vasti, soleus, gluteus maximus and gluteus medius produced the greatest muscle forces and negative (eccentric) mechanical work. Downward momentum of the centre-of-mass was resisted primarily by the soleus, vasti, gastrocnemius, rectus femoris, and gluteus maximus, whilst forward momentum was primarily resisted by the quadriceps (vasti and rectus femoris). Flexion of the lower limb joints was primarily resisted by the uni-articular gluteus maximus (hip), vasti (knee) and soleus (ankle). Overall, our findings provide a unique insight into the muscular strategy used by humans during a landing manoeuvre and have implications for the design of athletic training programs.

Effects of Elbow Crutch Locomotion on Gluteus Medius Activation During Stair Ascending

Crutches can help with the locomotion of people with walking disorders or functional limitations. However, little is known about hip muscle activation during stair ascending using different crutch locomotion patterns in people without disorders and limitations. Thus, we determined the acute effects of elbow crutch locomotion on gluteus medius (GM) activity during stair ascending. This comparative analytic cross-sectional study enrolled ten healthy men (22.0 ± 0.47 years). Participants climbed up the stairs with elbow crutches using one or two crutches, with ipsilateral or contralateral use, and after loading or unloading a limb. EMG signals were recorded from anterior, middle, and posterior portions of the GM and compared between the crutch conditions. The Kruskal-Wallis test and Dunn's multiple comparison test were performed (α = 5%). The activation of the GM increased with the ipsilateral use of crutches, with two crutches and three points, and when all the load depended only on one limb. GM activation decreased with contralateral use and in the unload limb. In conclusion, ascending stairs with elbow crutches alters the GM activation. The more critical factors were choosing the crutches' lateral use, the number of crutches, and if the limb is loaded or unloaded while ascending the stairs. Our findings can be helpful to increase or decrease the GM activation for those who use or will use crutches.

Psychological Aspects of Stair Use: A Systematic Review

Stair use, a common lifestyle activity, is a moderate-to-vigorous physical activity that, despite often being brief in duration, may contribute to psychological health. A systematic literature review was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) method to summarize psychological aspects related to stair use. Included studies examined at least 1 psychological outcome in relation to either objective measures of stair use, such as time or stair height, or subjective measures of, or measures related to, stair use such as perceived difficulty using stairs. A total of 22 studies met the inclusion criteria; 12 used subjective stair use measures and 10 used objective stair use measures. The limited evidence from studies using self-reports supported that (1) perceived difficulty using stairs was positively associated with increased symptoms of anxiety and depression and (2) stair use was not associated with a reduced incidence of mental illnesses such as depression, suicide, or dementia. Studies using objective measures of stair use supported that (3) elevated symptoms of anxiety and depression are negatively associated with stair use performance. Given the widespread use of stairs, there is surprisingly little data about the extent to which, and for whom, stair use influences psychological health.

Stability During Stairmill Ascent With Upward and Downward Applied Forces on the Pelvis

This study investigates how external vertical forces on the pelvis change the stability of stairmill climbing and other gait parameters such as kinematics and muscle activity. We use a Tethered Pelvic Assist Device (TPAD) to apply forces on the pelvis during continuous ascent on a stairmill. Ten young healthy subjects participated in three one-minute stair ascent with no force, a 10% body weight (BW) downward force, and a 10% BW upward force applied on the pelvis. The stability is determined by evaluating the base of support (BoS) and margin of stability (MoS). Kinematics and muscle activities were used to characterize the biomechanical changes. The results show that the upward forces applied on the pelvis decreased the (i) MoS by 1.84cm in the lateral direction, 2.07cm in the anterior direction, (ii) double stance phase by 1.85%, and (iii) the knee flexion by 5°. Furthermore, the peak activation levels of the muscles rectus femoris (RF), vastus lateralis (VL), and left gastrocnemius decreased. In contrast, the downward forces applied on the pelvis increased (i) the MOS by 1.5cm in the anterior direction and (ii) mean activation levels of RF and VL muscles. This study provides insights into the effects of applied vertical forces on the pelvis during stair ascent. These findings contribute to the understanding of the gait parameter changes and their relation with stability. Results could be used as a basis for designing training protocols to improve balance during stair ascent.

Age-related compensation: Neuromusculoskeletal capacity, reserve & movement objectives

The prevention, mitigation and treatment of movement impairments, ideally, requires early diagnosis or identification. As the human movement system has physiological and functional redundancy, movement limitations do not promptly arise at the onset of physical decline. A such, prediction of movement limitations is complex: it is unclear how much decline can be tolerated before movement limitations start. Currently, the term 'homeostatic reserve' or 'physiological reserve' is used to refer to the redundancy of the human biological system, but these terms do not describe the redundancy in the muscle architecture of the human body. The result of functional redundancy is compensation. Although compensation is an early predictor of movement limitations, clear definitions are lacking and the topic is underexposed in literature. The aim of this article is to provide a definition of compensation and emphasize its importance. Compensation is defined as an alteration in the movement trajectory and/or altering muscle recruitment to complete a movement task. Compensation for capacity is the result of a lack in neuromusculoskeletal reserve, where reserve is defined as the difference between the capacity (physiological abilities of the neuromusculoskeletal system) and the task demand. Compensation for movement objectives is a result of a shift in weighting of movement objectives, reflecting changing priorities. Studying compensation in biomechanics requires altered protocols in experimental set-ups, musculoskeletal models that are not reliant on prescribed movement, and inclusion of alternative movement objectives in optimal control theory.

Muscle Contributions to Balance Control During Amputee and Nonamputee Stair Ascent

Dynamic balance is controlled by lower-limb muscles and is more difficult to maintain during stair ascent compared to level walking. As a result, individuals with lower-limb amputations often have difficulty ascending stairs and are more susceptible to falls. The purpose of this study was to identify the biomechanical mechanisms used by individuals with and without amputation to control dynamic balance during stair ascent. Three-dimensional muscle-actuated forward dynamics simulations of amputee and nonamputee stair ascent were developed and contributions of individual muscles, the passive prosthesis, and gravity to the time rate of change of angular momentum were determined. The prosthesis replicated the role of nonamputee plantarflexors in the sagittal plane by contributing to forward angular momentum. The prosthesis largely replicated the role of nonamputee plantarflexors in the transverse plane but resulted in a greater change of angular momentum. In the frontal plane, the prosthesis and nonamputee plantarflexors contributed oppositely during the first half of stance while during the second half of stance, the prosthesis contributed to a much smaller extent. This resulted in altered contributions from the intact leg plantarflexors, vastii and hamstrings, and the intact and residual leg hip abductors. Therefore, prosthetic devices with altered contributions to frontal-plane angular momentum could improve balance control during amputee stair ascent and minimize necessary muscle compensations. In addition, targeted training could improve the force production magnitude and timing of muscles that regulate angular momentum to improve balance control.

Influence of high-heeled shoe parameters on biomechanical performance of young female adults during stair ascent motion

BACKGROUND

High-heeled shoes are currently preferred by women due to contemporary aesthetics. However, high-heeled shoes may increase the effort required to ascend stairs and, hence, alter biomechanical performance.

RESEARCH QUESTION

How do high-heel shoe parameters affect the pelvis position, lower extremities kinematics, and ground reaction force in young women during stair ascent motion?

METHODS

Stair ascent experiments were performed with 20 healthy adult women. The participants were instructed to ascend a 3-step staircase, wearing heeled shoes of different heel heights and heel types and one pair of flat shoes as the control group. Changes in lower body biomechanics were analyzed with kinematics and ground reaction force variables collected from the dominant limb. A two-way repeated ANOVA was performed to determine which variables were affected by heel type and which were affected by heel height or a combination of both.

RESULTS

As the heel height increased, an increased range of ankle dorsiflexion-plantarflexion, as well as pelvic rotation, was observed(P = 0.039 and P = 0.003, respectively). A thinner heel type displayed a larger pelvic forward tilt movement(P = 0.026)and 1st peak vertical force(P = 0.025), as well as a smaller 2nd peak vertical force (P = 0.002). With high heels, increased external rotation of the knee, inversion and plantar flexion, and flexion values of the knee were observed. We also observed decreased external rotation of the pelvis, ankle eversion, varum, and dorsiflexion.

SIGNIFICANCE

To stabilize body posture during stair ascent motion with high-heeled shoes, compensatory response including increasd pelvic range of motion and changing the joint angles of the lower extremities.

Robotic body weight support enables safe stair negotiation in compliance with basic locomotor principles

BACKGROUND

After a neurological injury, mobility focused rehabilitation programs intensively train walking on treadmills or overground. However, after discharge, quite a few patients are not able to independently negotiate stairs, a real-world task with high physical and psychological demands and a high injury risk. To decrease fall risk and improve patients' capacity to navigate typical environments, early stair negotiation training can help restore competence and confidence in safe stair negotiation. One way to enable early training in a safe and permissive environment is to unload the patient with a body weight support system. We here investigated if unloaded stair negotiation complies with basic locomotor principles, in terms of enabling performance of a physiological movement pattern with minimal compensation.

METHODS

Seventeen able-bodied participants were unloaded with 0-50% bodyweight during self-paced ascent and descent of a 4-tread staircase. Spatio-temporal parameters, joint ranges of motion, ground reaction forces and myoelectric activity in the main lower limb muscles of participants were compared between unloading levels. Likelihood ratio tests of separated linear mixed models of the investigated outcomes assessed if unloading affects the parameters in general. Subsequent post-hoc testing revealed which levels of unloading differed from unsupported stair negotiation.

RESULTS

Unloading affected walking velocity, joint ranges of motion, vertical ground reaction force parameters and myoelectric activity in all investigated muscles for stair ascent and descent while step width and single support duration were only affected during ascent. A reduction with increasing levels of body weight support was seen in walking velocity (0.07-0.12 m/s), ranges of motion of the knee and hip (2-10°), vertical ground reaction force peaks (10-70%) and myoelectric activity (17-70%). An increase with unloading was only seen during ascent for ankle range of motion and tibialis anterior activity at substantial unloading.

CONCLUSIONS

Body weight support facilitates stair negotiation by providing safety and support against gravity. Although unloading effects are present in most parameters, up to 30% body weight support these changes are small, and no dysfunctional patterns are introduced. Body weight support therefore fulfills all the necessary requirements for early stair negotiation training.

Evaluation of a low-technology system to obtain morphological and mobility trial measurements in dogs and investigation of potential predictors of canine mobility

OBJECTIVE

To develop a low-technology system that can be used by dog owners to obtain morphological and mobility measurements in companion dogs as candidate components of an eventual canine frailty scale.

ANIMALS

57 adult (≥ 1-year-old) dogs enrolled by 43 owners.

PROCEDURES

Morphological measurements of dogs were performed by investigators and dog owners. Dogs participated in timed in-clinic mobility trials across a flat surface (on-leash trial with the owner, on-leash trial with the investigator, and off-leash trial) and on stairs; each trial was repeated 3 times. Owners were asked to conduct a second stair trial at home 2 weeks later. Agreement between owner- and investigator-obtained measurements was assessed with Shrout-Fleiss intraclass correlation coefficients and paired t tests. Age, quartile of projected percentage of mean life span attained (adjusted for body weight), and height were evaluated as predictors of speed and stride length in mobility trials with linear regression and Spearman rank correlation analysis.

RESULTS

Agreement between owner- and investigator-obtained morphological measurements was strong. Age was a weak but significant predictor of decreased dog speed in mobility trials (adjusted R², 0.10 to 0.23). Speed decreased significantly with increasing quartile of projected life span attained. A linear regression model that included height and age predicted dog speed better than models with age or height alone.

CONCLUSIONS AND CLINICAL RELEVANCE

Morphological and mobility trial measurements can be obtained by dog owners with minimal training. Low-technology measurements of mobility trial speed offer potential as components in a future scoring scale for canine frailty.

Muscle Function and Coordination of Amputee Stair Ascent

Ascending stairs is challenging following transtibial amputation due to the loss of the ankle muscles, which are critical to human movement. Efforts to improve stair ascent following amputation are hindered by limited understanding of how prostheses and remaining muscles contribute to stair ascent. This study developed a three-dimensional muscle-actuated forward dynamics simulation of amputee stair ascent to identify contributions of individual muscles and passive prosthesis to the biomechanical subtasks of stair ascent. The prosthesis was found to provide vertical propulsion throughout stair ascent, similar to non-amputee plantarflexors. However, the timing differed considerably. The prosthesis also contributed to braking, similar to non-amputee soleus, but to a greater extent. In contrast, the prosthesis was unable to replicate the functions of non-amputee gastrocnemius which contributes to forward propulsion during the second half of stance and leg swing initiation. To compensate, hamstrings and vasti of the residual leg increased their contributions to forward propulsion during the first and second halves of stance, respectively. The prosthesis also contributed to medial control, consistent with the non-amputee soleus but not gastrocnemius. Therefore, prosthesis designs that provide additional vertical propulsion as well as forward propulsion, lateral control and leg swing initiation at appropriate points in the gait cycle could improve amputee stair ascent. However, because non-amputee soleus and gastrocnemius contribute oppositely to many subtasks, it may be necessary to couple the prosthesis, which functions most similarly to soleus, with targeted rehabilitation programs focused on muscle groups that can compensate for gastrocnemius.

Nondestructive Estimation of Muscle Contributions to STS Training with Different Loadings Based on Wearable Sensor System

Partial body weight support or loading sit-to-stand (STS) rehabilitation can be useful for persons with lower limb dysfunction to achieve movement again based on the internal residual muscle force and external assistance. To explicate how the muscles contribute to the kinetics and kinematics of STS performance by non-invasive in vitro detection and to nondestructively estimate the muscle contributions to STS training with different loadings, a wearable sensor system was developed with ground reaction force (GRF) platforms, motion capture inertial sensors and electromyography (EMG) sensors. To estimate the internal moments of hip, knee and ankle joints and quantify the contributions of individual muscle and gravity to STS movement, the inverse dynamics analysis on a simplified STS biomechanical model with external loading is proposed. The functional roles of the lower limb individual muscles (rectus femoris (RF), gluteus maximus (GM), vastus lateralis (VL), tibialis anterior (TA) and gastrocnemius (GAST)) during STS motion and the mechanism of the muscles' synergies to perform STS-specific subtasks were analyzed. The muscle contributions to the biomechanical STS subtasks of vertical propulsion, anteroposterior (AP) braking and propulsion for body balance in the sagittal plane were quantified by experimental studies with EMG, kinematic and kinetic data.