scholarly journals Obesity does not impair walking economy across a range of speeds and grades

2013 ◽  
Vol 114 (9) ◽  
pp. 1125-1131 ◽  
Author(s):  
Raymond C. Browning ◽  
Michelle M. Reynolds ◽  
Wayne J. Board ◽  
Kellie A. Walters ◽  
Raoul F. Reiser
Keyword(s):  
Oxygen Consumption ◽  
Metabolic Rate ◽  
Ground Reaction Forces ◽  
Step Width ◽  
External Work ◽  
Double Support ◽  
Primary Determinant ◽  
Reaction Forces ◽  
Walking Economy ◽  
Walking Speeds

Despite the popularity of walking as a form of physical activity for obese individuals, relatively little is known about how obesity affects the metabolic rate, economy, and underlying mechanical energetics of walking across a range of speeds and grades. The purpose of this study was to quantify metabolic rate, stride kinematics, and external mechanical work during level and gradient walking in obese and nonobese adults. Thirty-two obese [18 women, mass = 102.1 (15.6) kg, BMI = 33.9 (3.6) kg/m2; mean (SD)] and 19 nonobese [10 women, mass = 64.4 (10.6) kg, BMI = 21.6 (2.0) kg/m2] volunteers participated in this study. We measured oxygen consumption, ground reaction forces, and lower extremity kinematics while subjects walked on a dual-belt force-measuring treadmill at 11 speeds/grades (0.50–1.75 m/s, −3° to +9°). We calculated metabolic rate, stride kinematics, and external work. Net metabolic rate (Ėnet/kg, W/kg) increased with speed or grade across all individuals. Surprisingly and in contrast with previous studies, Ėnet/kg was 0–6% less in obese compared with nonobese adults ( P = 0.013). External work, although a primary determinant of Ėnet/kg, was not affected by obesity across the range of speeds/grades used in this study. We also developed new prediction equations to estimate oxygen consumption and Ėnet/kg and found that Ėnet/kg was positively related to relative leg mass and step width and negatively related to double support duration. These results suggest that obesity does not impair walking economy across a range of walking speeds and grades.

scholarly journals Metabolic cost of generating horizontal forces during human running

1999 ◽  
Vol 86 (5) ◽  
pp. 1657-1662 ◽  
Author(s):  
Young-Hui Chang ◽  
Rodger Kram
Keyword(s):  
Body Weight ◽  
Oxygen Consumption ◽  
Metabolic Cost ◽  
Ground Reaction Forces ◽  
Vertical Force ◽  
Order Of Magnitude ◽  
Reaction Forces ◽  
The Cost ◽  
Support Body Weight ◽  
Human Running

Previous studies have suggested that generating vertical force on the ground to support body weight (BWt) is the major determinant of the metabolic cost of running. Because horizontal forces exerted on the ground are often an order of magnitude smaller than vertical forces, some have reasoned that they have negligible cost. Using applied horizontal forces (AHF; negative is impeding, positive is aiding) equal to −6, −3, 0, +3, +6, +9, +12, and +15% of BWt, we estimated the cost of generating horizontal forces while subjects were running at 3.3 m/s. We measured rates of oxygen consumption (V˙o 2) for eight subjects. We then used a force-measuring treadmill to measure ground reaction forces from another eight subjects. With an AHF of −6% BWt,V˙o 2 increased 30% compared with normal running, presumably because of the extra work involved. With an AHF of +15% BWt, the subjects exerted ∼70% less propulsive impulse and exhibited a 33% reduction inV˙o 2. Our data suggest that generating horizontal propulsive forces constitutes more than one-third of the total metabolic cost of normal running.

scholarly journals Gait Dynamics on a Cross-Slope Walking Surface

2010 ◽  
Vol 26 (1) ◽  
pp. 17-25 ◽  
Author(s):  
Philippe C. Dixon ◽  
David J. Pearsall
Keyword(s):  
Lower Limb ◽  
Ground Reaction Forces ◽  
Adult Males ◽  
Step Width ◽  
Leg Length ◽  
Gait Dynamics ◽  
The Us ◽  
Reaction Forces ◽  
Restricted Mobility ◽  
Joint Reaction

The purpose of this study was to determine the effect of cross-slope on gait dynamics. Ten young adult males walked barefoot along an inclinable walkway. Ground reaction forces (GRFs), lower-limb joint kinematics, global pelvis orientation, functional leg-length, and joint reaction moments (JRMs) were measured. Statistical analyses revealed differences across limbs (up-slope [US] and down-slope [DS]) and inclinations (level; 0°; and cross-sloped, 6°). Adaptations included increases of nearly 300% in mediolateral GRFs (p< .001), functional shortening the US-limb and elongation of the DS-limb (p< .001), reduced step width (p= .024), asymmetrical changes in sagittal kinematics and JRM, and numerous pronounced coronal plane differences including increased US-hip adduction (and adductor moment) and decreased DS-hip adduction (and adductor moment). Data suggests that modest cross-slopes can induce substantial asymmetrical changes in gait dynamics and may represent a physical obstacle to populations with restricted mobility.

Is Altitude Training Bad for the Running Mechanics of Middle-Distance Runners?

2020 ◽  
pp. 1-4
Author(s):  
Grégoire P. Millet ◽  
Rosalie Trigueira ◽  
Frédéric Meyer ◽  
Marcel Lemire
Keyword(s):  
National Level ◽  
Moderate Intensity ◽  
Ground Reaction Forces ◽  
Altitude Training ◽  
Mechanical Parameters ◽  
External Work ◽  
Peak Knee ◽  
Reaction Forces ◽  
Running Biomechanics ◽  
Running Mechanics

Aims: It has been hypothesized that altitude training may alter running mechanics due to several factors such as the slower training velocity with associated alteration in muscle activation and coordination. This would lead to an altered running mechanics attested by an increase in mechanical work for a given intensity and to the need to “re-establish” the neuromuscular coordination and running biomechanics postaltitude. Therefore, the present study aimed to test the hypothesis that “live high—train high” would induce alteration in the running biomechanics (ie, longer contact time, higher vertical oscillations, decreased stiffness, higher external work). Methods: Before and 2 to 3 days after 3 weeks of altitude training (1850–2200 m), 9 national-level middle-distance (800–5000 m) male runners performed 2 successive 5-minute bouts of running at moderate intensity on an instrumented treadmill with measured ground reaction forces and gas exchanges. Immediately after the running trials, peak knee extensor torque was assessed during isometric maximal voluntary contraction. Results: Except for a slight (−3.0%; P = .04) decrease in vertical stiffness, no mechanical parameters (stride frequency and length, contact and flight times, ground reaction forces, and kinetic and potential work) were modified from prealtitude to postaltitude camp. Running oxygen cost was also unchanged. Discussion: The present study is the first one to report that “live high—train high” did not change the main running mechanical parameters, even when measured immediately after the altitude camp. This result has an important practical implication: there is no need for a corrective period at sea level for “normalizing” the running mechanics after an altitude camp.

scholarly journals Race Walking Ground Reaction Forces at Increasing Speeds: A Comparison with Walking and Running

Symmetry ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 873
Author(s):  
Gaspare Pavei ◽  
Dario Cazzola ◽  
Antonio La Torre ◽  
Alberto E. Minetti
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
The Body ◽  
Ground Reaction Forces ◽  
Centre Of Mass ◽  
Walking Gait ◽  
Wide Range ◽  
Reaction Forces ◽  
Race Walking ◽  
Walking Speeds

Race walking has been theoretically described as a walking gait in which no flight time is allowed and high travelling speed, comparable to running (3.6–4.2 m s−1), is achieved. The aim of this study was to mechanically understand such a “hybrid gait” by analysing the ground reaction forces (GRFs) generated in a wide range of race walking speeds, while comparing them to running and walking. Fifteen athletes race-walked on an instrumented walkway (4 m) and three-dimensional GRFs were recorded at 1000 Hz. Subjects were asked to performed three self-selected speeds corresponding to a low, medium and high speed. Peak forces increased with speeds and medio-lateral and braking peaks were higher than in walking and running, whereas the vertical peaks were higher than walking but lower than running. Vertical GRF traces showed two characteristic patterns: one resembling the “M-shape” of walking and the second characterised by a first peak and a subsequent plateau. These different patterns were not related to the athletes’ performance level. The analysis of the body centre of mass trajectory, which reaches its vertical minimum at mid-stance, showed that race walking should be considered a bouncing gait regardless of the presence or absence of a flight phase.

Synergies in the ground reaction forces and moments during double support in curb negotiation in young and older adults

2020 ◽  
Vol 106 ◽  
pp. 109837
Author(s):  
Chuyi Cui ◽  
Ashwini Kulkarni ◽  
Shirley Rietdyk ◽  
Fabio A. Barbieri ◽  
Satyajit Ambike
Keyword(s):  
Older Adults ◽  
Ground Reaction Forces ◽  
Double Support ◽  
Reaction Forces

scholarly journals THE USE OF HEART RATE TO ESTIMATE OXYGEN CONSUMPTION OF FREE-RANGING BLACK-BROWED ALBATROSSES DIOMEDEA MELANOPHRYS

1994 ◽  
Vol 193 (1) ◽  
pp. 119-137 ◽  
Author(s):  
R M Bevan ◽  
A J Woakes ◽  
P J Butler ◽  
I L Boyd
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Metabolic Rate ◽  
Calibration Procedure ◽  
Energy Budgets ◽  
Doubly Labelled Water ◽  
Heart Rate Data ◽  
Significant Difference ◽  
Walking Speeds ◽  
Free Ranging

Heart rates (fh) and rates of oxygen consumption (V(dot)O2) were measured in eight black-browed albatrosses (Diomedea melanophrys) when walking on a treadmill, with the aim of using fh to predict V(dot)O2 in free-ranging albatrosses. The resulting relationship between the variables was: V(dot)O2 (ml min-1) = [0.0157fh (beats min-1)]1.60, r2=0.80, P&lt;0.001. In addition to the calibration procedure, six of the albatrosses were injected with doubly labelled water (DLW), and fh and V(dot)O2 were monitored continuously over a 3 day period while the birds were held in a respirometer. During the 3 day period, the birds were walked for up to 3&shy;4 h day-1 in bouts lasting approximately 0.5 h. The heart rate data were used to estimate the metabolic rates of these birds using the above regression. Estimates of metabolic rate derived from fh, DLW and respirometry did not differ (ANOVA; P=0.94), primarily because of the variance between individual birds. There was also no significant difference between the different estimates obtained from the different equations used to calculate energy expenditure from the DLW technique (ANOVA; P=0.95). Mean estimates of V(dot)O2 from fh under active and inactive conditions differed from measured values of V(dot)O2 by -5.9 % and -1.7 % respectively. In addition, the estimates of V(dot)O2 from fh at different walking speeds did not differ significantly from the measured values. It appears that, in the black-browed albatross, fh is as good a predictor of the mean metabolic rate of free-ranging birds as DLW or time&shy;energy budgets combined with either respirometry or DLW. However, the method should be applied to as many individuals and as many instances of a particular behaviour as possible. The heart rate technique offers potential for much more detailed analyses of the daily energy budgets of these birds, and over much longer periods, than has previously been possible.

Experimental/Analytical Analysis of Human Locomotion Using Bondgraphs

2003 ◽  
Vol 125 (4) ◽  
pp. 490-498 ◽  
Author(s):  
Cristian Pop ◽  
Amir Khajepour ◽  
Jan P. Huissoon ◽  
Aftab E. Patla
Keyword(s):  
Equations Of Motion ◽  
Force Plate ◽  
Human Locomotion ◽  
Ground Reaction Forces ◽  
Phase Detection ◽  
Body Structure ◽  
Double Support ◽  
Model Predictions ◽  
Reaction Forces ◽  
Good Agreement

A new vectorial bondgraph approach for modeling and simulation of human locomotion is introduced. The vectorial bondgraph is applied to an eight-segment gait model to derive the equations of motion for studying ground reaction forces (GRFs) and centers of pressure (COPs) in single and double support phases of ground and treadmill walking. A phase detection technique and accompanying transition equation is proposed with which the GRFs and COPs may be calculated for the transitions from double-to-single and single-to-double support phases. Good agreement is found between model predictions and experimental data obtained from force plate measurements. The bondgraph modeling approach is shown to be both informative and adaptable, in the sense that the model resembles the human body structure, and that modeled body segments can be easily added or removed.

Evaluation of the Load Reduction Performance via a Suspended Backpack with Adjustable Stiffness

2021 ◽  
Author(s):  
Zhenhua Yang ◽  
Ledeng Huang ◽  
Ziniu Zeng ◽  
Ruishi Wang ◽  
Ruizhe Hu ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Energy Cost ◽  
Metabolic Cost ◽  
Ground Reaction Forces ◽  
Load Reduction ◽  
Joint Injuries ◽  
Reaction Forces ◽  
Walking Speeds ◽  
Healthy Participants

Abstract Backpacks are essential for travel but carrying a load during a long journey can easily cause muscle fatigue and joint injuries. Previous studies have suggested that suspended backpacks can effectively reduce the energy cost while carrying loads. Researchers have found that adjusting the stiffness of a suspended backpack can optimize its performance. Therefore, this paper proposes a stiffness-adjustable suspended backpack; the system stiffness can be adjusted to suitable values at different speeds. The stiffness of the suspended backpack with a 5-kg load was designed to be 690 N/m for a speed of 4.5 km/h, and it was adjusted to 870 and 1050 N/m at speeds of 5.5 and 6.5 km/h, respectively. The goal of this study was to determine how carrying a stiffness-adjustable suspended backpack affected performance while carrying a load. Six healthy participants participated in experiments where they wore two backpacks under three conditions: the adjustable-stiffness suspended backpack condition (S_A), the unadjustable-stiffness suspended backpack condition (S_UA), and the ordinary backpack condition (ORB). Our results showed that the peak accelerations, muscle activities, and peak ground reaction forces in the S_A condition were reduced effectively by adjusting the stiffness to adapt to different walking speeds; this adjustment decreased the metabolic cost by 4.21 ± 1.21% and 2.68 ± 0.88% at 5.5 km/h and 4.27 ± 1.35% and 3.38± 1.31% at 6.5 km/h compared to the ORB and S_UA, respectively.

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