The influence of anthropometric factor on the leg movement and muscle recruitment during bi-pedaling

Objective This study examined a system-level perspective to investigate the changes in the whole trunk and head postures while sitting with various lower extremity postures. Background Sitting biomechanics has focused mainly on the lumbar region only, whereas the anatomy literature has suggested various links from the head and lower extremity. Method Seventeen male participants were seated in six lower extremity postures, and the trunk kinematics and muscle activity measures were captured for 5 s. Results Changes in the trunk-thigh angle and the knee angle affected the trunk and head postures and muscle recruitment patterns significantly, indicating significant interactions between the lower extremity and trunk while sitting. Specifically, the larger trunk-thigh angle (T135°) showed more neutral lumbar lordosis (4.0° on average), smaller pelvic flexion (1.8°), smaller head flexion (3.3°), and a less rounded shoulder (1.7°) than the smaller one (T90°). The smaller knee angle (K45°) revealed a more neutral lumbar lordosis (6.9°), smaller pelvic flexion (9.2°), smaller head flexion (2.6°), and less rounded shoulder (2.4°) than the larger condition (K180°). The more neutral posture suggested by the kinematic measures confirmed significantly less muscular recruitment in the trunk extensors, except for a significant antagonistic co-contraction. Conclusion The lower and upper back postures were more neutral, and back muscle recruitment was lower with a larger trunk-thigh angle and a smaller knee angle, but at the cost of antagonistic co-contraction. Application The costs and benefits of each lower extremity posture can be used to design an ergonomic chair and develop an improved sitting strategy.

Download Full-text

Simulation of athlete gait recognition based on spectral features and machine learning

Journal of Intelligent & Fuzzy Systems ◽

10.3233/jifs-189568 ◽

2020 ◽

pp. 1-12

Author(s):

Linuo Wang

Keyword(s):

Machine Learning ◽

Angular Velocity ◽

Gait Recognition ◽

Spectral Feature ◽

Velocity Signal ◽

Comparison Results ◽

Computer Vision Technology ◽

Feature Technology ◽

Leg Movement ◽

Recognition Efficiency

The current technology related to athlete gait recognition has shortcomings such as complicated equipment and high cost, and there are also certain problems in recognition accuracy and recognition efficiency. In order to improve the efficiency of athletes’ gait recognition, this paper studies the different recognition technologies of athletes based on machine learning and spectral feature technology and applies computer vision technology to sports. Moreover, according to the calf angular velocity signal, the occurrence of leg movement is detected in real time, and the gait cycle is accurately divided to reduce the influence of the signal unrelated to the behavior on the recognition process. In addition, this study proposes a gait behavior recognition method based on event-driven strategies. This method uses a gyroscope as the main sensor and uses a wearable sensor node to collect the angular velocity signals of the legs and waist. In addition, this study analyzes the performance of the algorithm proposed by this paper through experimental research. The comparison results show that the method proposed by this paper has improved the number of recognition action types and accuracy and has certain advantages from the perspective of computation and scalability.

Download Full-text

PHOTOKINESIS AND TONIC EFFECT OF LIGHT IN UNIONICOLA

The Journal of General Physiology ◽

10.1085/jgp.16.2.349 ◽

1932 ◽

Vol 16 (2) ◽

pp. 349-355 ◽

Cited By ~ 14

Author(s):

John H. Welsh

Keyword(s):

Light Intensity ◽

Simple Relation ◽

Combined Effect ◽

Direct Proportion ◽

Water Mite ◽

Locomotor Muscles ◽

Leg Movement ◽

Changing Light ◽

Effect Of Light

1. The speed of progression of Unionicola, a water mite, is influenced by light; and over a certain range increases as a function of the light intensity. 2. The relation between speed and light intensity is not a simple one, as the speed of progression is due to the combined effect of amplitude of steps and frequency of leg movement. 3. The amplitude of stride increases in direct proportion to the logarithm of the light intensity, while the frequency of stepping has no such simple relation to intensity. 4. The change in length of stride with changing light intensity indicates a tonic effect of light on the locomotor muscles. Such an effect has been observed previously in studies of orientation, due to unequal illumination, which produces changes in posture.

Download Full-text

Associations between low back pain, urinary incontinence, and abdominal muscle recruitment as assessed via ultrasonography in the elderly

Brazilian Journal of Physical Therapy ◽

10.1590/bjpt-rbf.2014.0073 ◽

2015 ◽

Vol 19 (1) ◽

pp. 70-76 ◽

Cited By ~ 4

Author(s):

Vânia F. Figueiredo ◽

Juleimar S. C. Amorim ◽

Aline M. Pereira ◽

Paulo H. Ferreira ◽

Leani S. M. Pereira

Keyword(s):

Urinary Incontinence ◽

Low Back Pain ◽

Back Pain ◽

The Elderly ◽

Abdominal Muscle ◽

Low Back ◽

Muscle Recruitment

Download Full-text

Reading the copepod personal ads: increasing encounter probability with hydromechanical signals

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.1998.0235 ◽

1998 ◽

Vol 353 (1369) ◽

pp. 691-700 ◽

Cited By ~ 19

Author(s):

Luca A. van Duren ◽

Eize J. Stamhuis ◽

John J. Videler

Keyword(s):

Flow Field ◽

Laser Sheet ◽

Surrounding Water ◽

Encounter Probability ◽

Velocity Gradients ◽

Swimming Motion ◽

Image Velocimetry ◽

Temora Longicornis ◽

Leg Movement ◽

Swimming Leg

Females of the calanoid copepod Temora longicornis react to chemical exudates of male conspecifics with little hops, quite distinct from their normal smooth uniform swimming motion. These hops possibly serve to create a hydrodynamical signal in the surrounding water, to increase encounter probability with potential mates. Laser sheet particle image velocimetry was used to investigate the flow fields associated with these hops and to compare them to the flow of the feeding current of an adult female. During, and immediately after a hop, the flow field around the copepod showed a marked difference from that of a foraging animal. During foraging, the highest velocity gradients were located around the feeding appendages of the copepod. During a hop, high velocity gradients are located behind the animal. About 0.5 seconds after the start of swimming leg movement, effects of the hop had virtually dissipated and the flow field resembled that around a foraging animal. The estimated volume of influence (i.e. the volume around the copepod where the animal has a significant influence on the water) increased about 12–fold during the hop compared with the situation around a foraging animal. Furthermore, the rate of viscous energy dissipation within the copepods' volume of influence increased nearly 80–fold. Hops may serve to increase encounter probability, but due to the short duration of the effect and the high energetic costs they would only be adaptive when other cues have indicated that suitable sexual partners are in the vicinity.

Download Full-text