Cinematographic Analysis of Mechanical Energy Expenditure in the Sprinter*-->

1931 ◽  
Vol 16 (5) ◽  
pp. 603-611
Author(s):  
C. A. Morrison ◽  
W. O. Fenn
Keyword(s):  
Energy Expenditure ◽  
Mechanical Energy

Kinematic Coordination in Human Gait: Relation to Mechanical Energy Cost

1998 ◽  
Vol 79 (4) ◽  
pp. 2155-2170 ◽  
Author(s):  
L. Bianchi ◽  
D. Angelini ◽  
G. P. Orani ◽  
F. Lacquaniti
Keyword(s):  
Energy Expenditure ◽  
Energy Cost ◽  
Time Course ◽  
Sagittal Plane ◽  
Dimensional Space ◽  
Mechanical Energy ◽  
Direction Cosine ◽  
Lower Limbs ◽  
Human Gait ◽  
Plane Orientation

Bianchi, L., D. Angelini, G. P. Orani, and F. Lacquaniti. Kinematic coordination in human gait: relation to mechanical energy cost. J. Neurophysiol. 79: 2155–2170, 1998. Twenty-four subjects walked at different, freely chosen speeds ( V) ranging from 0.4 to 2.6 m s−1, while the motion and the ground reaction forces were recorded in three-dimensional space. We considered the time course of the changes of the angles of elevation of the trunk, pelvis, thigh, shank, and foot in the sagittal plane. These angles specify the orientation of each segment with respect to the vertical and to the direction of forward progression. The changes of the trunk and pelvis angles are of limited amplitude and reflect the dynamics of both right and left lower limbs. The changes of the thigh, shank, and foot elevation are ample, and they are coupled tightly among each other. When these angles are plotted one versus the others, they describe regular loops constrained on a plane. The plane of angular covariation rotates, slightly but systematically, along the long axis of the gait loop with increasing V. The rotation, quantified by the change of the direction cosine of the normal to the plane with the thigh axis ( u 3 t ), is related to a progressive phase shift between the foot elevation and the shank elevation with increasing V. As a next step in the analysis, we computed the mass-specific mean absolute power ( P u ) to obtain a global estimate of the rate at which mechanical work is performed during the gait cycle. When plotted on logarithmic coordinates, P u increases linearly with V. The slope of this relationship varies considerably across subjects, spanning a threefold range. We found that, at any given V > 1 m s−1, the value of the plane orientation ( u 3 t ) is correlated with the corresponding value of the net mechanical power ( P u ). On the average, the progressive rotation of the plane with increasing V is associated with a reduction of the increment of P u that would occur if u 3 t remained constant at the value characteristic of low V. The specific orientation of the plane at any given speed is not the same in all subjects, but there is an orderly shift of the plane orientation that correlates with the net power expended by each subject. In general, smaller values of u 3 t tend to be associated with smaller values of P u and vice versa. We conclude that the parametric tuning of the plane of angular covariation is a reliable predictor of the mechanical energy expenditure of each subject and could be used by the nervous system for limiting the overall energy expenditure.

scholarly journals Spring-like leg behaviour, musculoskeletal mechanics and control in maximum and submaximum height human hopping

2011 ◽  
Vol 366 (1570) ◽  
pp. 1516-1529 ◽  
Author(s):  
Maarten F. Bobbert ◽  
L. J. Richard Casius
Keyword(s):  
Energy Expenditure ◽  
Muscle Activation ◽  
Mechanical Energy ◽  
Reaction Force ◽  
Ground Reaction Forces ◽  
Centre Of Mass ◽  
Leg Stiffness ◽  
Reaction Forces ◽  
And Control ◽  
The Relationship

The purpose of this study was to understand how humans regulate their ‘leg stiffness’ in hopping, and to determine whether this regulation is intended to minimize energy expenditure. ‘Leg stiffness’ is the slope of the relationship between ground reaction force and displacement of the centre of mass (CM). Variations in leg stiffness were achieved in six subjects by having them hop at maximum and submaximum heights at a frequency of 1.7 Hz. Kinematics, ground reaction forces and electromyograms were measured. Leg stiffness decreased with hopping height, from 350 N m −1 kg −1 at 26 cm to 150 N m −1 kg −1 at 14 cm. Subjects reduced hopping height primarily by reducing the amplitude of muscle activation. Experimental results were reproduced with a model of the musculoskeletal system comprising four body segments and nine Hill-type muscles, with muscle stimulation STIM( t ) as only input. Correspondence between simulated hops and experimental hops was poor when STIM( t ) was optimized to minimize mechanical energy expenditure, but good when an objective function was used that penalized jerk of CM motion, suggesting that hopping subjects are not minimizing energy expenditure. Instead, we speculated, subjects are using a simple control strategy that results in smooth movements and a decrease in leg stiffness with hopping height.

Mechanical energy expenditure of subject with multiple sclerosis engaged in daily activities: a case study

2013 ◽  
Vol 16 (sup1) ◽  
pp. 134-135
Author(s):  
V. Serrau ◽  
F. Ayachi ◽  
L. Fradet ◽  
F. Marin ◽  
V. Leclercq ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Energy Expenditure ◽  
Mechanical Energy ◽  
Daily Activities

Mechanical Energy Changes and the Oxygen Cost of Running

1981 ◽  
Vol 10 (4) ◽  
pp. 213-217 ◽  
Author(s):  
M R Shorten ◽  
S A Wootton ◽  
C Williams
Keyword(s):  
Energy Transfer ◽  
Energy Expenditure ◽  
Mechanical Energy ◽  
Three Dimensional ◽  
Whole Body ◽  
Net Energy ◽  
Oxygen Cost ◽  
Transfer Condition ◽  
Energy Transfers ◽  
Highly Correlated

The relationship between the oxygen cost of running at submaximal speeds and running mechanics was investigated in a group of trained athletes by means of an energy analysis. Subjects were filmed while running on a motorized treadmill at speeds of 3.58, 4.02, 4.47, 4.92, 5.36, and 5.81 m/s. Segmental potential and kinetic energies were determined using a three-dimensional link-segmental model. Intra-stride changes in the energy of the whole body were computed with no allowance for energy transfer and with various energy transfer constraints imposed on the model. Oxygen consumption was determined by expired air analysis and used to estimate energy expenditure. For each transfer condition, net energy expenditure was more highly correlated with the magnitude of intra-stride energy changes than with running speed per se. The more economic running patterns were characterized by greater within-segment energy transfers. Given the limitations of the kinematic energy model, it is suggested that individual patterns of running are a significant factor in the determination of energy expenditure.

Analytical Description of Minimum Energy Expenditure Surfaces

1988 ◽  
Vol 110 (4) ◽  
pp. 386-391 ◽  
Author(s):  
D. J. Winarski ◽  
J. R. Pearson
Keyword(s):  
Energy Expenditure ◽  
Mechanical Energy ◽  
Minimum Energy ◽  
Analytical Description ◽  
Flexion Extension ◽  
Optimal Adjustment ◽  
Point Set ◽  
Alignment Angle ◽  
Energy Surfaces ◽  
Over Time

Mechanical energy expenditure during level walking was evaluated and graphed for two unilateral, below-knee amputees over time and a range of adjustments of the flexion-extension alignment angle. The resulting mechanical energy surfaces were then least-squared fitted with an analytical function that was linear in time and quadratic in flexion-extension alignment angle. The least-squares analysis showed that there was a flexion-extension adjustment that minimized the mechanical energy expenditure and that this optimal adjustment was very close to the design point set by certified prosthetists.

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