Human Finger Independence: Limitations due to Passive Mechanical Coupling Versus Active Neuromuscular Control

2004 ◽  
Vol 92 (5) ◽  
pp. 2802-2810 ◽  
Author(s):  
Catherine E. Lang ◽  
Marc H. Schieber
Keyword(s):  
Neuromuscular Control ◽  
The Other ◽  
Passive Condition ◽  
Mechanical Coupling ◽  
Complete Independence ◽  
Active Condition ◽  
Middle Ring ◽  
Human Finger ◽  
Passive Movements ◽  
Flexion And Extension

We studied the extent to which mechanical coupling and neuromuscular control limit finger independence by studying passive and active individuated finger movements in healthy adults. For passive movements, subjects relaxed while each finger was rotated into flexion and extension by a custom-built device. For active movements, subjects moved each finger into flexion and extension while attempting to keep the other, noninstructed fingers still. Active movements were performed through approximately the same joint excursions and at approximately the same speeds as the passive movements. We quantified how mechanical coupling limited finger independence from the passive movements, and quantified how neuromuscular control limited finger independence using an analysis that subtracted the indices obtained in the passive condition from those obtained in the active condition. Finger independence was generally similar during passive and active movements, but showed a trend toward less independence in the middle, ring, and little fingers during active, large-arc movements. Mechanical coupling limited the independence of the index, middle, and ring fingers to the greatest degree, followed by the little finger, and placed only negligible limitations on the independence of the thumb. In contrast, neuromuscular control primarily limited the independence of the ring, and little fingers during large-arc movements, and had minimal effects on the other fingers, especially during small-arc movements. For the movement conditions tested here, mechanical coupling between the fingers appears to be a major factor limiting the complete independence of finger movement.

Considering a Meso-Ergonomic Factor: Can Accountability Reduce Errors?

2020 ◽  
Vol 64 (1) ◽  
pp. 288-292
Author(s):  
Pouria Salehi ◽  
Erin K. Chiou
Keyword(s):  
High Throughput ◽  
Job Design ◽  
The Other ◽  
Active Group ◽  
Quality Performance ◽  
Passive Condition ◽  
X Ray ◽  
High Security ◽  
Active Condition ◽  
Passive Group

Accountability is an ill-defined and underexplored concept in job design, particularly in highly proceduralized environments that must operate under both high throughput and high-security expectations. Using x-ray images from the Airport Scanner game, this paper investigates two mechanisms of accountability: an active condition, and a passive condition. Each group was shown a list of prohibited items, but different feedback was provided. The active group was asked to be vigilant for any possible threat, whereas the passive group was instructed to stick to the list. Data from 76 participants were collected. The active group took longer (+16%) to process fewer (-10%) x-ray images compared to the passive group. As a result, the active group accomplished fewer hits (-14%), but also fewer misses (-31%) compared to the other group. While the active group worked slower, they provided higher quality performance. We conclude that accountability mechanisms can reduce errors if applied appropriately.

scholarly journals Neuromuscular Control of the Knee during a Resisted Single-Limb Squat Exercise

2005 ◽  
Vol 33 (10) ◽  
pp. 1520-1526 ◽  
Author(s):  
Richard K. Shields ◽  
Sangeetha Madhavan ◽  
Emy Gregg ◽  
Jennifer Leitch ◽  
Ben Petersen ◽  
...  
Keyword(s):  
Body Weight ◽  
Knee Joint ◽  
Knee Flexion ◽  
Neuromuscular Control ◽  
Biceps Femoris ◽  
Medial Gastrocnemius ◽  
Isometric Contractions ◽  
Low Resistance ◽  
Squat Exercise ◽  
Flexion And Extension

Background Closed kinetic chain exercises such as single-limb squats are preferred for knee rehabilitation. A complete understanding of the neuromuscular control of the knee during the single-limb squat is essential to increase the efficiency of rehabilitation programs. Hypothesis Performing a controlled single-limb squat with resistance to knee flexion and extension will increase the coactivation of the hamstring muscle group, thus reducing the quadriceps/hamstrings ratio. Study Design Descriptive laboratory study. Methods A total of 15 healthy human subjects (7 women, 8 men) performed controlled single-limb squats in a custom mechanical device that provided resistance to both flexion and extension. Subjects performed the task at 3 levels of resistance, set as a percentage of body weight. Surface electromyographic recordings from 7 muscles (gluteus medius, rectus femoris, vastus medialis oblique, vastus lateralis, biceps femoris, semitendinosus, and medial gastrocnemius) were collected during the task. Results Biceps femoris activity during knee flexion increased from approximately 12% maximum voluntary isometric contractions during low resistance (0% body weight) to approximately 27% maximum voluntary isometric contractions during high resistance (8% body weight). Although the quadriceps had greater activity than the hamstrings at all levels of resistance, the quadriceps/hamstrings ratio declined significantly with resistance (F2,27 = 29.05; P=. 012) from 3.0 at low resistance to 2.32 at the highest resistance. Conclusions Performing controlled resisted single-limb squats may help to simultaneously strengthen the quadriceps and facilitate coactivation of the hamstrings, thus reducing anterior tibial shear forces. The coactivation may also increase the dynamic control of the knee joint. Clinical Relevance The typical single-limb squat exercise performed in the clinic does not usually control for bidirectional resistance and knee joint excursion. As seen in this study, controlled single-limb squats at increased levels of resistance help to increase the coactivation of the hamstring muscles, which is essential to optimize neuromuscular control of the knee.

Nationalism and Decolonization in Cameroon

2019 ◽  
Author(s):  
Joseph Takougang
Keyword(s):  
Democratic Party ◽  
Nation Building ◽  
The Other ◽  
The West ◽  
Nationalist Party ◽  
National Convention ◽  
Complete Independence ◽  
French Colonial ◽  
British Colonial ◽  
The Republic

The union between the former French Cameroun and the British Southern Cameroons on October 1, 1961, to form the Federal Republic of Cameroon was a unique experiment in nation building and the struggle for independence in Africa. For instance, the Union des Populations du Cameroun (UPC), the first truly nationalist party in the former French trusteeship that advocated immediate independence and reunification with the British Cameroons, was banned in May 1955 by French colonial authorities because of its radical views, since France was still reluctant to grant its African colonies complete independence. For France, the choice of who and which party could lead the territory to independence depended on who French authorities thought could guarantee continued relations with France following independence. In the end, Ahmadou Ahidjo and his Union Camerounaise (UC) emerged as the best candidate to meet France’s objectives in a postcolonial Cameroun. On the other hand, because of the colonial arrangement that allowed Britain to administer its section of the former German colony as part of its colony of Nigeria to the west, the nationalist struggle took a different trajectory and was more against Nigerian rather than British colonial domination. In other words, for many Southern Cameroonians, the focus by the two major parties (Kamerun National Democratic Party (KNDP) and Cameroons Peoples’ National Convention (CPNC)) during the campaign leading to the plebiscite on February 11, 1961, was whether the territory should be part of the Republic of Cameroun, which was engulfed in violence and bloodshed following its independence on January 1, 1960, or face the threat of Igbo domination if Southern Cameroonians decided to become part of an independent Nigeria.

Development of Active and Passive Fatigue Manipulations Using a Driving Simulator

2007 ◽  
Vol 51 (18) ◽  
pp. 1237-1241 ◽  
Author(s):  
Dyani J. Saxby ◽  
Gerald Matthews ◽  
Edward M. Hitchcock ◽  
Joel S. Warm
Keyword(s):  
Time Course ◽  
Passive Control ◽  
Driving Simulator ◽  
Negative Mood ◽  
Subjective Response ◽  
Passive Condition ◽  
Full Control ◽  
Active Condition ◽  
The Impact ◽  
Simulated Wind

The present study investigates driving simulator methodologies for inducing qualitatively different patterns of subjective response. The study tested Desmond and Hancock's (2001) theory that there may be two types of fatigue: active and passive. 108 undergraduates participated. There were 3 conditions (active, passive, control) and 3 durations (10, 30, 50 minutes). The active condition used simulated wind gusts to increase the required number of steering and acceleration changes. The passive condition was fully automated. In the control condition, drivers were in full control of steering and acceleration. Task engagement (e.g., energy) was lowest in the passive fatigue condition, followed by the control and active conditions. Distress (e.g., negative mood) was found to be highest in the active fatigue condition. The time course of fatigue responses was also determined. The results suggest methods for developing manipulations to determine the impact of fatigue on performance.

Generalization of Training Speaking Skills: The Role of Overt Activity, Feedback, and Child's Initial Level of Competence

1988 ◽  
Vol 66 (3) ◽  
pp. 963-978
Author(s):  
Luc Reid ◽  
Monique Lefebvre-Pinard ◽  
Adrien Pinard
Keyword(s):  
Initial Level ◽  
Feedback Condition ◽  
Referential Communication ◽  
Communication Behaviors ◽  
Passive Condition ◽  
Active Condition ◽  
Training Exercises ◽  
Transfer Tasks ◽  
Speaking Skills

72 children (mean age = 6–5) were assigned to 1 of 6 training conditions for speaking skills in a 2 (with or without feedback) × 3 (degree of overt activity) crossed design. Children in the active condition participated directly in three training exercises; each child in the passive condition observed the performance of the child in the active condition to whom he was matched; children in the active-passive condition received a combination of the two previous treatments. Children were given a pretest and immediate and delayed posttests, each of which was comprised of five tasks, four of which aimed at measuring possible transfer to other referential communication behaviors. Posttest evaluations showed that improvements in speaking behavior were related to the feedback condition, but not to the child's initial level of competence as assessed by global performance on the five pretest tasks. The reverse was true for the four transfer tasks. The amount of overt activity did not exert a significant effect on children's performance of any of the five tasks. Possible causes of the difficulty of obtaining transfer in training experiments are discussed.

Co-Contraction Recruitment and Spinal Load during Isometric Pushing Tasks

2005 ◽  
Vol 49 (14) ◽  
pp. 1330-1333 ◽  
Author(s):  
Kevin Granata ◽  
Patrick Lee ◽  
Tim Franklin
Keyword(s):  
Biomechanical Model ◽  
Neuromuscular Control ◽  
Surface Emg ◽  
Trunk Flexion ◽  
Materials Handling ◽  
Manual Materials Handling ◽  
Muscle Groups ◽  
Spinal Load ◽  
Theoretical Analyses ◽  
Flexion And Extension

Pushing and pulling tasks account for 20% of occupational low-back injury claims but few studies have investigated the neuromuscular control of the spine during these tasks. Primary torso muscle groups recruited during pushing tasks include the rectus abdominis and external obliques. However, theoretical analyses suggest that co-contraction of the paraspinal muscles is necessary to stabilize the spine during flexion exertions. A biomechanical model was implemented to estimate co-contraction and spinal load from measured surface EMG and trunk moment data recorded during trunk flexion and extension exertions. Results demonstrate that co-contraction during flexion exertions was approximately twice the value of co-contraction during extension. Co-contraction accounted for up to 47% of the total spinal load during flexion exertions and spinal load attributed to co-contraction was nearly 50% greater during flexion than during extension exertions despite similar levels of trunk moment. Results underscore the need to consider neuromuscular recruitment when evaluating biomechanical risks. Keywords: Spine; Co-contraction; Push; Manual Materials Handling; Biomechanics

scholarly journals VIII. Observations on coprozoic flagellates: Together with a suggestion as to the significance of the kinetonucleus in the binucleata

1916 ◽  
Vol 207 (335-347) ◽  
pp. 375-412 ◽  
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Alimentary Canal ◽  
The Other ◽  
Considerable Time ◽  
Parasitic Fauna ◽  
History Of ◽  
Active Condition ◽  
Soil Protozoa ◽  
The Subject

Since publishing, with Mr. Lapage, the first account of the life-cycle of Helkesimastix facicola , I have continued to work alone on the biology and life-history of the flagellates occurring in simple dung-cultures. In the course of this investigation, I have made certain observations which I wish here to record, together with one or two suggestions which I have to offer. The work promises to occupy considerable time before it is completed, and in the case of some of the forms studied I am not yet able to describe the life-cycle in its entirety. Little or no attention has been paid hitherto to the protozoa active in dung, and the study of this fauna is probably not without interest and importance in connection with the subject of the soil-protozoa. To distinguish those protozoa which are carried through the alimentary canal in a passive, encysted condition and become active and go through their life-history in the moist dung, Prof. Minchin has suggested, in the course of his lectures, the useful term coprozoic . The coprozoic fauna of goats and sheep is entirely different from their parasitic fauna, which has for its principal habitat the rumen. Neither the various specialised ciliates (of the fam. Ophryoscolecidæ ) nor the flagellates ( Sphæromonas , Trichomastix and Callimastix ), some of which are invariably present in the rumen, ever occur in an active condition in dung-cultures; and, on the other hand, I have never found any of the coprozoic flagellates active in the rumen-contents, when freshly examined. These facts, readily determined because the sets of forms in the two cases are entirely different, afford important confirmation of the view, now generally accepted, that the Entamæbæ —the truly parasitic forms—are quite distinct from the Amoebæ which develop in fæcal cultures, i. e .,coprozoic species.

scholarly journals Variables Associated with Performance of an Active Limb Movement following Within-Session Instruction in People with and People without Low Back Pain

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Sara A. Scholtes ◽  
Barbara J. Norton ◽  
Sara P. Gombatto ◽  
Linda R. Van Dillen
Keyword(s):  
Low Back Pain ◽  
Back Pain ◽  
Movement Patterns ◽  
Movement Pattern ◽  
Limb Movement ◽  
Low Back ◽  
Similar Relationship ◽  
Passive Condition ◽  
Active Condition ◽  
And Gender

Modification of a movement pattern can be beneficial in decreasing low back pain (LBP) symptoms. There is variability, however, in how well people are able to modify performance of a movement. What has not been identified is the factors that may affect a person’s ability to modify performance of a movement. We examined factors related to performance of active hip lateral rotation (HLR) following standardized instructions in people with and people without LBP. Data were collected during performance of HLR under 3 conditions: passive, active, and active instructed. In people with LBP, motion demonstrated during the passive condition (r=0.873,P<0.001), motion demonstrated during the active condition (r=0.654,P=0.008), and gender (r=0.570,P=0.027) were related to motion demonstrated during the active-instructed condition. Motion demonstrated during the passive condition explained 76%(P<0.001)of the variance in motion demonstrated during the active-instructed condition. A similar relationship did not exist in people without LBP. The findings of the study suggest that it may be important to assess motion demonstrated during passive HLR to determine how difficult it will be for someone with LBP to modify the performance of HLR. Prognosis should be worst for those who display similar movement patterns during passive HLR and active-instructed HLR.

Conceptual Design for Condylar Guiding Features of a Total Knee Replacement

2011 ◽  
Vol 5 (2) ◽  
Author(s):  
Shahram Amiri ◽  
T. Derek V. Cooke ◽  
Urs P. Wyss
Keyword(s):  
Total Knee Replacement ◽  
Conceptual Design ◽  
Knee Replacement ◽  
The Other ◽  
Lateral Condyle ◽  
Total Knee ◽  
Design Requirements ◽  
Replacement System ◽  
Flexion And Extension ◽  
Femoral Condyles

This study investigates the design requirements for guiding features that can be incorporated into the shapes of the femoral condyles and the tibial component geometry of a knee replacement system without occupying the intercondylar space of the joint so that the cruciates can be spared and still produce more physiological motions. A conceptual design for a surface-guided knee is introduced to induce effective guiding both in flexion and extension by novel features incorporated in the shape of the lateral condyle. This design can accommodate preservation of either of the cruciates while deficiencies in the functions of the other are compensated by contributions of the articular geometry in guiding the motion and stabilizing the joint. The preliminary kinematic tests on a prototype demonstrated viability of the features in guiding motion under compression.

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