Exploring the possibility of mechanical energy as a multipurpose evaluation function for learning of whole body dynamic motions

Author(s):  
Yuya Yumoto ◽  
Ikuo Mizuuchi
1997 ◽  
Vol 272 (1) ◽  
pp. E45-E50 ◽  
Author(s):  
P. Balagopal ◽  
O. Ljungqvist ◽  
K. S. Nair

Mixed muscle protein synthetic rate has been measured in humans. These measurements represent the average of synthetic rates of all muscle proteins with variable rates. We determined to what extent the synthesis rate of mixed muscle protein in humans reflects that of myosin heavy chain (MHC), the main contractile protein responsible for the conversion of ATP to mechanical energy as muscle contraction. Fractional synthetic rates of MHC and mixed muscle protein were measured from the increment of [13C]leucine in these proteins in vastus lateralis biopsy samples taken at 5 and 10 h during a primed continuous infusion of L-[1-13C]leucine in 10 young healthy subjects. Calculations were done by use of plasma [13C]ketoisocaproate (KIC) and muscle tissue fluid [13C]leucine as surrogate measures of leucyl-tRNA. Fractional synthetic rate of MHC with plasma KIC (0.0299 +/- 0.0043%/h) and tissue fluid leucine (0.0443 +/- 0.0056%/h) were only 72 +/- 3% of that of mixed muscle protein (0.0408 +/- 0.0032 and 0.0603 +/- 0.0059%/h, respectively, with KIC and tissue fluid leucine). Contribution of MHC (7 +/- 1 mg.kg-1.h-1) to synthetic rates of whole body mixed muscle protein (36 +/- 5 mg.kg-1.h-1) and whole body protein (127 +/- 4 mg.kg-1.h-1) is only 18 +/- 1 and 5 +/- 1%, respectively. This relatively low contribution of MHC to whole body and mixed muscle protein synthesis warrants direct measurement of synthesis rate of MHC in conditions involving abnormalities of muscle contractile function.


Author(s):  
Sébastien Ratel ◽  
Craig A Williams

Scientific evidence supports the proposition that prepubertal children fatigue less than adults when performing whole-body dynamic activities like maximal cycling, running bouts, and maximal voluntary isometric/isokinetic muscle contractions. Although the mechanisms underpinning differences in fatigue between children and adults are not all fully understood, there is a consensus that children experience less peripheral fatigue (i.e. muscular fatigue) than their older counterparts. Central factors may also account for the lower fatigability in children. Some studies report a higher reduction of muscle voluntary activation during fatiguing exercise in prepubertal children compared to adults. This could reflect a strategy of the central nervous system aimed at limiting the recruitment of motor units, in order to prevent any extensive peripheral fatigue. Further studies are required to clarify this proposition.


1988 ◽  
Vol 4 (3) ◽  
pp. 231-259 ◽  
Author(s):  
Ross H. Sanders ◽  
Barry D. Wilson

This study investigated factors contributing to the maximum height achieved by divers after takeoff from the 3m springboard. Twelve elite male divers and 12 elite female divers competing in the 1986 Australian National Championships were filmed using high-speed cinematography. Kinematic and kinetic data for the takeoff phase were derived from the digitized film. Variables analyzed included center of gravity (CG) displacement and velocity, the acceleration of the CG relative to the springboard, and the components of mechanical energy contributing to height achieved by the diver’s CG. Body orientation was described in terms of the angles at the hip, knee, and ankle, and whole body angle of lean. Comparison of timing differences among dive groups and divers was aided by normalizing the data with respect to time. It was found that the height achieved was highly dependent on the rotational requirements of the dive, with males achieving greater heights than females. Divers who achieve good height compared to other divers performing the same dive are characterized by a large vertical velocity at touchdown from the hurdle and a minimization of hip flexion (forward dives) and knee flextion (reverse dives) at takeoff.


Author(s):  
Atushi Nakano ◽  
Hidekazu Kawashima ◽  
Yosinori Miyake ◽  
Tatsuya Sawamura ◽  
Hidehiro Iid

2013 ◽  
Vol 10 (2-3) ◽  
pp. 97-111
Author(s):  
M. Saiful Huq ◽  
M. O. Tokhi

A simulation based study of a completely new form of body-weight supported treadmill training (BWSTT) technique which is fully passive in nature is presented in this paper. The approach does not require any powered means at the lower limbs and is implemented using a combination of coordinated joint locking/unlocking and flexible torque transfer mechanisms. The hip extension pertaining to the stance phase of the gait cycle is achieved through the stance foot being literally dragged by the treadmill belt while the required manoeuvring of the trunk is expected to be accomplished by the voluntary arm-support from the subject. The swing phase, on the other hand, is initiated through appropriately coupling the swing knee with the contralateral extending hip and eventually achieve full knee extension through switching the treadmill speed to a lower value. Considering adequate support from the able arms, the process effectively turns the frictional force at the foot-treadmill belt interface into an agent causing the required whole body mechanical energy fluctuation during the gait cycle.The simulation platform consists of a dynamic planer (sagittal) full body humanoid model along with the treadmill model developed within a CAD based software environment interfaced with passive viscoelastic joint properties implemented in Simulink. The voluntary upper body effort as well as control of the gait cycle are also developed within MATLAB/Simulink environment. The gait cycle generated using the new concept is thoroughly investigated through this simulation study.


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