scholarly journals Size and Shape: Morphology's Impact on Human Speed and Mobility

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
Cara M. Wall-Scheffler
Keyword(s):  
Sexual Dimorphism ◽  
Metabolic Rate ◽  
Reproductive Strategies ◽  
Walking Speed ◽  
Size Variation ◽  
Human Populations ◽  
Optimal Speed ◽  
Metabolic Costs ◽  
Walking Speeds ◽  
Tibia Length

While human sexual dimorphism is generally expected to be the result of differential reproductive strategies, it has the potential to create differences in the energetics of locomotion and the speed at which each morph travels, particularly since people have been shown to choose walking speeds around their metabolic optimum. Here, people of varying sizes walked around a track at four self-selected speeds while their metabolic rate was collected, in order to test whether the size variation within a population could significantly affect the shape of the optimal walking curve. The data show that larger people have significantly faster optimal walking speeds, higher costs at their optimal speed, and a more acute optimal walking curve (thus an increased penalty for walking at suboptimal speeds). Bigger people who also have wider bitrochanteric breadths have lower metabolic costs at their minimum than bigger people with a more narrow bitrochanteric breadth. Finally, tibia length significantly positively predicts optimal walking speed. These results suggest sex-specific walking groups typical of living human populations may be the result of energy maximizing strategies. In addition, testable hypotheses of group strategies are put forth.

scholarly journals The Influence of Powered Prostheses on User Perspectives, Metabolics and Activity: A Randomized Crossover Trial

2020 ◽  
Author(s):  
Jay Kim ◽  
Jeffrey Wensman ◽  
Natalie Colabianchi ◽  
Deanna Gates
Keyword(s):  
Walking Speed ◽  
Daily Life ◽  
Step Count ◽  
Free Form ◽  
Objective Measures ◽  
Daily Step ◽  
Metabolic Costs ◽  
Daily Step Count ◽  
Powered Prosthesis ◽  
Walking Speeds

Abstract Background: Powered prosthetic ankles provide battery-powered mechanical push-off, with the aim of reducing the metabolic demands of walking for people with transtibial amputations. The efficacy of powered ankles has been shown in active, high functioning individuals with transtibial amputation, but is less clear in other populations. Additionally, it is unclear how powered prosthetic use influences everyday physical activity and mobility.Methods: Individuals with unilateral transtibial amputations participated in a randomized clinical trial comparing their prescribed, unpowered prosthesis and the BiOM powered prosthesis. Participants’ metabolic costs and self-selected walking speeds were measured in the laboratory and daily step count, daily steps away from home, and walking speed were measured over two weeks of at-home prosthetic use. Participants also rated their perception of mobility and quality of life and provided free-form feedback. Dependent measures were compared between prostheses and the relationships between metabolic cost, perception of mobility, and characteristics of walking in daily life were explored using Pearson’s correlations.Results: Twelve people were randomly allocated to the powered prosthesis first (n = 7) or unpowered prosthesis first (n = 5) and ten completed the full study. There were no differences in metabolic costs (p = 0.585), daily step count (p = 0.995), walking speed (p ≥ 0.145), or perception of mobility between prostheses (p ≥ 0.058). Changes varied across participants, however. There were several medium- and large-sized effects for device comparisons. With the powered prosthesis, participants had decreased walking speeds in daily life (g = 0.310), increased self-reported ambulation (g = 0.682), and decreased frustration (g = 0.506). Greater preference for the powered prosthesis was moderately correlated with increased everyday walking speed (r = 0.636, p = 0.090).Conclusions: There were no universal benefits of the powered prosthesis on function in the lab or home environment. However, the effects were subject-specific, with some reporting preference for power and improved mobility, and some increasing their activity and decreasing their metabolic effort. Additionally, self-reported preferences did not often correlate with objective measures of function. This highlights the need for future clinical research to include both perception and objective measures to better inform prosthetic prescription.Trial registration: https://clinicaltrials.gov, #NCT02828982. Registered 12 July 2016, https://clinicaltrials.gov/ct2/show/NCT02828982

scholarly journals Impact of elastic ankle exoskeleton stiffness on neuromechanics and energetics of human walking across multiple speeds

2020 ◽  
Author(s):  
Richard W. Nuckols ◽  
Gregory S. Sawicki
Keyword(s):  
Metabolic Rate ◽  
Muscle Activation ◽  
Walking Speed ◽  
Metabolic Cost ◽  
Weighted Sum ◽  
Joint Mechanics ◽  
Metabolic Demand ◽  
Muscle Dynamics ◽  
Ankle Exoskeleton ◽  
Walking Speeds

Abstract Background: Elastic ankle exoskeletons with springs of intermediate stiffness springs in parallel with the human plantarflexors can reduce the metabolic cost of walking by ~7% at 1.25 m s-1. In a move toward ‘real-world’ application, we examined whether the unpowered approach has metabolic benefit across a range of walking speeds, and if so, whether the optimal exoskeleton stiffness was speed dependent. We hypothesized that there is an ‘optimal’ exoskeleton stiffness for any speed which minimizes the user’s metabolic rate and that the metabolically optimal exoskeleton stiffness will also increase with walking speed. Methods: Eleven participants walked on a level treadmill at 1.25, 1.50, and 1.75 m s-1 while we used a state-of-the-art exoskeleton emulator system to apply bilateral ankle exoskeleton assistance at five controlled rotational stiffnesses (kexo = 0, 50, 100, 150, 250 Nm rad-1). We measured metabolic cost, lower limb joint mechanics, and EMG of muscles crossing the ankle, knee, and hip. Results: We measured significant reductions in metabolic cost at the lowest exoskeleton stiffness (50 Nm rad-1) for assisted walking at both 1.25 (4.2%; p = 0.032) and 1.75 m s-1 (4.7%; p = 0.009). At these speeds, the metabolically optimal ankle exoskeleton stiffness provided peak assistive torques of ~0.20 Nm kg-1 that resulted in reduced biological ankle moment of ~12% and reduced soleus muscle activity of ~10%. We found no spring stiffness that could reduce the metabolic cost of walking at 1.5 m s-1. Across all speeds, the non-weighted sum of soleus and tibialis anterior activation rate explained the change metabolic rate due to exoskeleton assistance (p < .05; R2 > 0.56)). Conclusions: Elastic ankle exoskeletons with low rotational stiffness reduce users’ metabolic cost of walking at slow and fast walking speeds but not at intermediate walking speed. The relationship between the non-weighted sum of soleus and tibialis activation and metabolic cost (R2 > 0.56) indicates that muscle activation may drive metabolic demand. Future work using computer simulations and ultrasound imaging will get ‘under the skin’ and examine the interaction between exoskeleton stiffness and plantarflexor muscle dynamics to better inform stiffness selection in human-machine systems.

scholarly journals Impact of elastic ankle exoskeleton stiffness on neuromechanics and energetics of human walking across multiple speeds

2020 ◽  
Author(s):  
Richard W. Nuckols ◽  
Gregory S. Sawicki
Keyword(s):  
Metabolic Rate ◽  
Muscle Activation ◽  
Walking Speed ◽  
Metabolic Cost ◽  
Weighted Sum ◽  
Joint Mechanics ◽  
Muscle Dynamics ◽  
Activation Rate ◽  
Ankle Exoskeleton ◽  
Walking Speeds

Abstract Background: Elastic ankle exoskeletons with springs of intermediate stiffness in parallel with the human plantarflexors can reduce the metabolic cost of walking by ~7% at 1.25 m s -1 . In a move toward ‘real-world’ application, we examined whether the unpowered approach has metabolic benefit across a range of walking speeds, and if so, whether the optimal exoskeleton stiffness was speed dependent. We hypothesized that, for any walking speed, there would be an optimal ankle exoskeleton stiffness - not too compliant and not too stiff - that minimizes the user’s metabolic rate. In addition, we expected the optimal exoskeleton stiffness to increase with walking speed. Methods: Eleven participants walked on a level treadmill at 1.25, 1.50, and 1.75 m s -1 while we used a state-of-the-art exoskeleton emulator system to apply bilateral ankle exoskeleton assistance at five controlled rotational stiffnesses (k exo = 0, 50, 100, 150, 250 Nm rad -1 ). We measured metabolic cost, lower limb joint mechanics, and EMG of muscles crossing the ankle, knee, and hip. Results: We measured significant reductions in metabolic cost at the lowest exoskeleton stiffness (50 Nm rad -1 ) for assisted walking at both 1.25 (4.2%; p = 0.032) and 1.75 m s -1 (4.7%; p = 0.009). At these speeds, the metabolically optimal ankle exoskeleton stiffness provided peak assistive torques of ~0.20 Nm kg -1 that resulted in reduced biological ankle moment of ~12% and reduced soleus muscle activity of ~10%. We found no spring stiffness that could reduce the metabolic cost of walking at 1.5 m s -1 . Across all speeds, the non-weighted sum of soleus and tibialis anterior activation rate explained the change metabolic rate due to exoskeleton assistance ( p < .05; R 2 > 0.56)). Conclusions: Elastic ankle exoskeletons with low rotational stiffness reduce users’ metabolic cost of walking at slow and fast walking speeds but not at intermediate walking speed. The relationship between the non-weighted sum of soleus and tibialis activation rate and metabolic cost (R 2 > 0.56) indicates that muscle activation may drive metabolic demand. Future work using computer simulations and ultrasound imaging will get ‘under the skin’ and examine the interaction between exoskeleton stiffness and plantarflexor muscle dynamics to better inform stiffness selection in human-machine systems.

scholarly journals Myofascial Release of the Hamstrings Improves Physical Performance—A Study of Young Adults

Healthcare ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 674
Author(s):  
Keisuke Itotani ◽  
Kanta Kawahata ◽  
Wakana Takashima ◽  
Wakana Mita ◽  
Hitomi Minematsu ◽  
...  
Keyword(s):  
Young Adults ◽  
Physical Performance ◽  
Walking Speed ◽  
Quadriceps Muscle ◽  
Lower Limbs ◽  
Joint Movement ◽  
Myofascial Release ◽  
Functional Reach Test ◽  
Hamstring Flexibility ◽  
Walking Speeds

Physical performance is mainly assessed in terms of gait speed, chair rise capacity, and balance skills, and assessments are often carried out on the lower limbs. Such physical performance is largely influenced by the strength of the quadriceps and hamstrings muscles. Flexibility of the hamstrings is important because quadriceps muscle activity influences the hip flexion angle. Therefore, hamstring flexibility is essential to improve physical performance. In this study, Myofascial Release (MFR) was applied to the hamstrings to evaluate its effects. MFR on the hamstrings was performed on 17 young adults. Physical function and physical performance were measured before, immediately after, and 5 days after the MFR intervention: finger floor distance (FFD), range of motion (ROM) of the straight leg raising test (SLR), standing long jump (SLJ), squat jump (SJ), functional reach test (FRT), comfortable walking speeds (C-walking speed), and maximum walking speeds (M-walking speed). The results of the analysis show a significant increase in FFD (−2.6 ± 8.9 vs. 0.4 ± 9.4 vs. 2.4 ± 8.9, p < 0.01), SLJ (185.6 ± 44.5 vs. 185.0 ± 41.8 vs. 196.6 ± 40.1, p < 0.01), and M-walking speed (2.9 ± 0.6 vs. 3.0 ± 0.6 vs. 3.3 ± 0.6, p < 0.01). This study has shown that MFR for hamstrings not only improves flexibility but also increases M-walking speed and physical performance of the SLJ. As MFR is safe and does not involve joint movement, it may be useful for maintaining and improving performance and flexibility during inactivity and for stretching before exercise.

Pedestrian Behavior at Signalized Intersection Crosswalks: Observational Study of Factors Associated with Distracted Walking, Pedestrian Violations, and Walking Speed

2018 ◽  
Vol 2672 (35) ◽  
pp. 1-12 ◽  
Author(s):  
Brendan J. Russo ◽  
Emmanuel James ◽  
Cristopher Y. Aguilar ◽  
Edward J. Smaglik
Keyword(s):  
Traffic Safety ◽  
Walking Speed ◽  
The United States ◽  
Ordinary Least Squares ◽  
Signalized Intersections ◽  
Video Data ◽  
High Definition ◽  
Pedestrian Behavior ◽  
Factors Associated ◽  
Walking Speeds

In the past two decades, cell phone and smartphone use in the United States has increased substantially. Although mobile phones provide a convenient way for people to communicate, the distraction caused by the use of these devices has led to unintended traffic safety and operational consequences. Although it is well recognized that distracted driving is extremely dangerous for all road users (including pedestrians), the potential impacts of distracted walking have not been as comprehensively studied. Although practitioners should design facilities with the safety, efficiency, and comfort of pedestrians in mind, it is still important to investigate certain pedestrian behaviors at existing facilities to minimize the risk of pedestrian–vehicle crashes, and to reduce behaviors that may unnecessarily increase delay at signalized intersections. To gain new insights into factors associated with distracted walking, pedestrian violations, and walking speed, 3,038 pedestrians were observed across four signalized intersections in New York and Arizona using high-definition video cameras. The video data were reduced and summarized, and an ordinary least squares (OLS) regression model was estimated to analyze factors affecting walking speeds. In addition, binary logit models were estimated to analyze both pedestrian distraction and pedestrian violations. Ultimately, several site- and pedestrian-specific variables were found to be significantly associated with pedestrian distraction, violation behavior, and walking speeds. The results provide important information for researchers, practitioners, and legislators, and may be useful in planning strategies to reduce or mitigate the impacts of pedestrian behavior that may be considered unsafe or potentially inefficient.

scholarly journals Determinación del sexo a través de la métrica dental en cazadores recolectores de la transición pampeano-patagónica oriental / SEX DETERMINATION THROUGH DENTAL METRICS FOR HUNTER-GATHERER GROUPS FROM THE EASTERN PAMPA-PATAGONIAN TRANSITION

2017 ◽  
Vol 10 (1) ◽  
pp. 53 ◽  
Author(s):  
Leandro Luna ◽  
Gustavo Flensborg
Keyword(s):  
Sexual Dimorphism ◽  
Late Holocene ◽  
Colorado River ◽  
Human Populations ◽  
Hunter Gatherers ◽  
Dental Metrics ◽  
Sexual Information ◽  
Palabras Clave ◽  
Sexual Determination ◽  
Del Rio

<p>El objetivo de este trabajo es evaluar la pertinencia de la métrica dental para obtener información sexual en individuos que habitaron el curso inferior del río Colorado durante el Holoceno tardío (ca. 3000-250 años AP), discutir el grado de dimorfismo sexual e identificar las variables cuantitativas de la dentición que permitan discriminar el sexo de nuevos individuos que se incluyan en futuros análisis. Se estudiaron las medidas máximas bucolinguales y mesiodistales del cuello de los dientes correspondientes a 26 individuos adultos. Las variables más dimórficas corresponden al diámetro bucolingual del canino superior y de ambos segundos molares; en estos casos, las diferencias entre los sexos son estadísticamente significativas. Los resultados obtenidos sobre el dimorfismo sexual se ubican en el extremo superior de los valores correspondientes a diferentes poblaciones humanas. Varios individuos que no contaban con información sexual a través de los métodos tradicionales pudieron ser clasificados desde la métrica dental, lo cual da cuenta del importante potencial de las medidas dentales para contribuir a las caracterizaciones paleodemográficas de conjuntos bioarqueológicos, especialmente en contextos perturbados y con escasa integridad esqueletal.</p><p>Palabras clave: métrica dental; determinación sexual; cazadores-recolectores; curso inferior del río Colorado; Holoceno tardío.</p><p>Abstract<br />The aim of this paper is to evaluate the relevance of dental metrics for obtaining sexual information in individuals who inhabited the lower basin of the Colorado River during the Late Holocene (ca. 3000-250 years BP), to discuss the degree of sexual dimorphism and to identify those quantitative variables adequate for sexual determination of new individuals to be included in future studies. The buccolingual and mesiodistal maximum neck diameters of 26 individual adults were studied. The most dimorphic variables correspond to the buccolingual diameter of the upper canine and both second molars; in these cases, sex differences are statistically significant. The results obtained about sexual dimorphism are located at the upper end of the range for different human populations. Several individuals who had no previous sexual information could be classified using these measurements, which accounts for the significant potential of dental metrics in palaeodemographic characterizations, especially in disturbed bioarchaeological samples.</p><p>Keywords: dental metrics; sexual determination; hunter-gatherers; lower basin of the Colorado River; Late Holocene.</p>

Effects of Varying Overground Walking Speeds on Lower-Extremity Muscle Synergies in Healthy Individuals

Motor Control ◽  
2020 ◽  
pp. 1-18
Author(s):  
Manuel J. Escalona ◽  
Daniel Bourbonnais ◽  
Michel Goyette ◽  
Damien Le Flem ◽  
Cyril Duclos ◽  
...  
Keyword(s):  
Lower Extremity ◽  
Nonnegative Matrix Factorization ◽  
Walking Speed ◽  
Nonnegative Matrix ◽  
Gait Training ◽  
Muscle Synergies ◽  
Training Strategy ◽  
Lower Extremity Muscle ◽  
Walking Speeds ◽  
Weight Acceptance

The effects of walking speeds on lower-extremity muscle synergies (MSs) were investigated among 20 adults who walked 20 m at SLOW (0.6 ± 0.2 m/s), natural (NAT; 1.4 ± 0.1 m/s), and FAST (1.9 ± 0.1 m/s) speeds. Surface electromyography of eight lower-extremity muscles was recorded before extracting MSs using a nonnegative matrix factorization algorithm. Increasing walking speed tended to merge MSs associated with weight acceptance and limb deceleration, whereas reducing walking speed does not change the number and composition of MSs. Varying gait speed, particularly decreasing speed, may represent a gait training strategy needing additional attention given its effects on MSs.

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