scholarly journals Effects of Dental Occlusion on Body Sway, Upper Body Muscle Activity and Shooting Performance in Pistol Shooters

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Amândio A. Dias ◽  
Luís A. Redinha ◽  
Luís M. Silva ◽  
Pedro C. Pezarat-Correia
Keyword(s):  
Upper Limb ◽  
Muscle Activity ◽  
National Level ◽  
Body Posture ◽  
Upper Body ◽  
Body Sway ◽  
Dental Occlusion ◽  
Emg Activity ◽  
Experimental Conditions ◽  
Occlusal Splints

Occlusal splints, to some extent, have been related to reduced body sway in a static position and increased muscle activity in the upper limbs. However, how dental occlusion status affects sports performance remains unclear. Here, we investigated whether occlusal splints that reposition the temporomandibular joint (TMJ) influenced body posture, muscle activity, and performance in 10-meter pistol shooters. Thirteen national-level male shooters (age = 38.8 ± 10.9 yrs) were recruited for this study, and cleared of any cervical pathology. An occlusal splint (OS) and a placebo splint (PS) were fabricated for each of the subjects, with the mandibular and maxillary position verified by an expert dentist, with the aid of an adjustable articulator. Surface electromyography (EMG) was assessed in the upper limb that holds the pistol while the subjects were standing on a force platform. Subjects performed two series of 10 shots for each of the three experimental conditions (OS, PS, N (no splint)) in randomized order, with the mandible in a rest position. Results revealed similar centre of pressure (COP) parameters in all conditions, despite a reduction in the average oscillation area caused by the OS. There were also no significant differences in EMG activity between conditions in the five upper limb muscles monitored. Consistent with this, shooting performance was similar in all conditions, despite a reduction in shot dispersion in subjects using OS. Thus, changes in dental occlusion status induced by OS do not affect body posture, upper limb EMG muscle activity, or shot performance in healthy male pistol shooters.

Multidigit Control of Contact Forces During Transport of Handheld Objects

2007 ◽  
Vol 98 (2) ◽  
pp. 851-860 ◽  
Author(s):  
Sara A. Winges ◽  
John F. Soechting ◽  
Martha Flanders
Keyword(s):  
Contact Force ◽  
Muscle Activity ◽  
Center Of Mass ◽  
Contact Forces ◽  
Load Force ◽  
Emg Activity ◽  
Experimental Conditions ◽  
Contact Plane ◽  
Grasping Forces ◽  
Grasp Stability

When an object is lifted vertically, the normal force increases and decreases in tandem with tangential (load) force to safely avoid slips. For horizontal object transport, horizontal forces at the contact surfaces can be decomposed into manipulation forces (producing acceleration/deceleration) and grasping forces. Although the grasping forces must satisfy equilibrium constraints, it is not clear what determines their modulation across time, nor the extent to which they result from active muscle contraction or mechanical interactions of the digits with the moving object. Grasping force was found to increase in an experimental condition where the center of mass was below the contact plane, compared with when it was in the contact plane. This increase may be aimed at stabilizing object orientation during translation. In another experimental condition, more complex moments were introduced by allowing the low center of mass to swing around a pivot point. Electromyographic (EMG) activity recorded from several intrinsic and extrinsic hand muscles failed to reveal active feedback regulation of contact force in this situation. Instead, in all experimental conditions, EMG data revealed a strategy of feedforward stiffness modulation. Multiple regression analysis revealed that muscle activity at remote digits (e.g., the index and ring fingers) was highly correlated with the contact force measured at another digit (e.g., the thumb). The data suggest that to maintain grasp stability during horizontal translation, predictable as well as somewhat unpredictable inertial forces are compensated for by controlling the stiffness of the hand through cocontraction and modulation of hand muscle activity.

Alternate Leg Movement Amplifies Locomotor-Like Muscle Activity in Spinal Cord Injured Persons

2005 ◽  
Vol 93 (2) ◽  
pp. 777-785 ◽  
Author(s):  
Noritaka Kawashima ◽  
Daichi Nozaki ◽  
Masaki O. Abe ◽  
Masami Akai ◽  
Kimitaka Nakazawa
Keyword(s):  
Spinal Cord ◽  
Muscle Activity ◽  
Lower Limbs ◽  
Emg Activity ◽  
Joint Movement ◽  
Experimental Conditions ◽  
Biceps Femoris Muscle ◽  
Cord Injury ◽  
Leg Movement ◽  
The Right

It is now well recognized that muscle activity can be induced even in the paralyzed lower limb muscles of persons with spinal cord injury (SCI) by imposing locomotion-like movements on both of their legs. Although the significant role of the afferent input related to hip joint movement and body load has been emphasized considerably in previous studies, the contribution of the “alternate” leg movement pattern has not been fully investigated. This study was designed to investigate to what extent the alternate leg movement influenced this “locomotor-like” muscle activity. The knee-locked leg swing movement was imposed on 10 complete SCI subjects using a gait training apparatus. The following three different experimental conditions were adopted: 1) bilateral alternate leg movement, 2) unilateral leg movement, and 3) bilateral synchronous (in-phase) leg movement. In all experimental conditions, the passive leg movement induced EMG activity in the soleus and medial head of the gastrocnemius muscles in all SCI subjects and in the biceps femoris muscle in 8 of 10 SCI subjects. On the other hand, the EMG activity was not observed in the tibialis anterior and rectus femoris muscles. The EMG level of these activated muscles, as quantified by integrating the rectified EMG activity recorded from the right leg, was significantly larger for bilateral alternate leg movement than for unilateral and bilateral synchronous movements, although the right hip and ankle joint movements were identical in all experimental conditions. In addition, the difference in the pattern of the load applied to the leg among conditions was unable to explain the enhancement of EMG activity in the bilateral alternate leg movement condition. These results suggest that the sensory information generated by alternate leg movements plays a substantial role in amplifying the induced locomotor-like muscle activity in the lower limbs.

scholarly journals A Study of Postural Safety and Low-Cost Electromyography (EMG) Device Towards Grocery Workers in Kota Samarahan, Sarawak

2020 ◽  
Vol 4 (4) ◽  
pp. 1-5
Author(s):  
Mohd Azrin Mohd Said ◽  
Keyword(s):  
Upper Limb ◽  
Muscle Activity ◽  
Low Cost ◽  
The Body ◽  
Body Posture ◽  
Low Back ◽  
Emg Signal ◽  
Lower Back

Body posture is one of the most important parts when lifting an object as it can causes injury if the wrong technique and body posture were used. A worker will injure their low back if a bad posture is not in consideration. A good body posture is recommended among workers to reduce the chance of injury while lifting and improve their postural safety. The main objectives of this study are to observe the body posture of the worker during lifting and study the comparison of using lower back support when lifting. It also investigates the muscle activity of the worker during heavy lifting using EMG and simulates the worker's movement using CATIA Software for Rapid Upper Limb Assessment (RULA) results. The selected grocery was chosen in Kota Samarahan, Sarawak with 7 male respondents are identified to undergo this study. The results show that the worker with lower back support tends to show raw EMG signal with lower muscle activity compared to without using lower back support. Thus, using belt support can reduce muscle activity by up to 67.4% compare to not wearing back support. Raw EMG signals also show 3010 amplitude (mV) muscle activity if postural safety of the workers improved by following the NIOSH lifting Recommendations.

Shaping Appropriate Locomotive Motor Output Through Interlimb Neural Pathway Within Spinal Cord in Humans

2008 ◽  
Vol 99 (6) ◽  
pp. 2946-2955 ◽  
Author(s):  
Noritaka Kawashima ◽  
Daichi Nozaki ◽  
Masaki O. Abe ◽  
Kimitaka Nakazawa
Keyword(s):  
Spinal Cord ◽  
Upper Limb ◽  
Lower Limb ◽  
Muscle Activity ◽  
Swing Phase ◽  
Motor Output ◽  
Emg Activity ◽  
Limb Movements ◽  
Neural Connections ◽  
Upper Limb Movements

Direct evidence supporting the contribution of upper limb motion on the generation of locomotive motor output in humans is still limited. Here, we aimed to examine the effect of upper limb motion on locomotor-like muscle activities in the lower limb in persons with spinal cord injury (SCI). By imposing passive locomotion-like leg movements, all cervical incomplete ( n = 7) and thoracic complete SCI subjects ( n = 5) exhibited locomotor-like muscle activity in their paralyzed soleus muscles. Upper limb movements in thoracic complete SCI subjects did not affect the electromyographic (EMG) pattern of the muscle activities. This is quite natural since neural connections in the spinal cord between regions controlling upper and lower limbs were completely lost in these subjects. On the other hand, in cervical incomplete SCI subjects, in whom such neural connections were at least partially preserved, the locomotor-like muscle activity was significantly affected by passively imposed upper limb movements. Specifically, the upper limb movements generally increased the soleus EMG activity during the backward swing phase, which corresponds to the stance phase in normal gait. Although some subjects showed a reduction of the EMG magnitude when arm motion was imposed, this was still consistent with locomotor-like motor output because the reduction of the EMG occurred during the forward swing phase corresponding to the swing phase. The present results indicate that the neural signal induced by the upper limb movements contributes not merely to enhance but also to shape the lower limb locomotive motor output, possibly through interlimb neural pathways. Such neural interaction between upper and lower limb motions could be an underlying neural mechanism of human bipedal locomotion.

The impact of a total hip replacement on jaw position, upper body posture and body sway

CRANIO® ◽  
2014 ◽  
Vol 33 (2) ◽  
pp. 107-114 ◽  
Author(s):  
Daniela Ohlendorf ◽  
Christoph Lehmann ◽  
Daniel Heil ◽  
Stefan Hörzer ◽  
Stefan Kopp
Keyword(s):  
Total Hip Replacement ◽  
Hip Replacement ◽  
Body Posture ◽  
Upper Body ◽  
Body Sway ◽  
Total Hip ◽  
Upper Body Posture ◽  
Jaw Position ◽  
The Impact

Trunk and Upper Limb Muscle Activation During Flat and Topspin Forehand Drives in Young Tennis Players

2011 ◽  
Vol 27 (1) ◽  
pp. 15-21 ◽  
Author(s):  
Isabelle Rogowski ◽  
David Rouffet ◽  
Frédéric Lambalot ◽  
Olivier Brosseau ◽  
Christophe Hautier
Keyword(s):  
Upper Limb ◽  
Vertical Velocity ◽  
Muscle Activity ◽  
Muscle Activation ◽  
Emg Activity ◽  
Shoulder Abduction ◽  
Joint Angles ◽  
Tennis Players ◽  
Shoulder Muscle ◽  
Forearm Muscle

This study compared EMG activity of young tennis players’ muscles during forehand drives in two groups, GD—those able to raise by more than 150% the vertical velocity of racket-face at impact from flat to topspin forehand drives, and GND, those not able to increase their vertical velocity to the same extent. Upper limb joint angles, racket-face velocities, and average EMGrms values, were studied. At similar joint angles, a fall in horizontal velocity and a rise in racket-face vertical velocity from flat to topspin forehand drives were observed. Shoulder muscle activity rose from flat to topspin forehand drives in GND, but not for drives in GD. Forearm muscle activity reduced from flat to topspin forehand drives in GD, but muscle activation was similar in GND. The results show that radial deviation increased racket-face vertical velocity more at impact from the flat to topspin forehand drives than shoulder abduction.

scholarly journals Systematic changes of the static upper body posture with a symmetric occlusion condition

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
C. Maurer-Grubinger ◽  
I. Avaniadi ◽  
F. Adjami ◽  
W. Christian ◽  
C. Doerry ◽  
...  
Keyword(s):  
Sagittal Plane ◽  
Age Groups ◽  
Three Dimensional ◽  
Body Posture ◽  
Upper Body ◽  
Dental Occlusion ◽  
Trunk Length ◽  
Compensation Mechanisms ◽  
Upper Body Posture ◽  
Gender Specific

Abstract Background Temporary occlusal changes and their influence on the upper body statics are still controversially discussed. Furthermore, concrete statements on whether age- or gender-specific differences in neurophysiological reactions exist are missing. Therefore, it is the aim of this study to evaluate the immediate effects of a symmetrical occlusion blocking on the upper body posture. These effects shall be investigated for both genders and for a larger age range. Methods In this study, 800 (407f/393 m) subjects volunteered aged from 21 to 60 years. Both genders were divided into four age groups according to decades. The three-dimensional upper body posture was measured by using the rasterstereography (ABW-Bodymapper). The habitual static posture was measured in two dental occlusion conditions (a) in rest position and (b) symmetrical blocking in the bicuspid region by cotton rolls. Results A significant reduction of the trunk length (0.72 mm; p <  0.001), an increase of the lumbar (0.30°; p <  0.001) and the thoracic bending angle (0.14°; p = 0.001), a reduction of the spinal forward decline (0.16°; p <  0.001) and a reduction of the scapular distance (0.36 mm; p = 0.001) was found. Gender-specific reactions can only be recorded in scapular distance, in that regard men reduce this distance while over all age groups women did not show a significant change. Discussion Slight gender- and age-independent reactions due to a symmetric occlusion blockade are shown: A gender independent reaction of the spinal related variables in the sagittal plane (thoracic and lumbar flexion angle, trunk length, spinal forward decline). In addition, a gender specific change of the shoulder blade distance could be observed, where men reduced the distance while female did not show a change. However, since these reactions are of a minimum amount, it can be concluded that neurophysiological compensation mechanisms work equally well regardless of age and sex, and the upper body posture of healthy people changes only very slightly due to a temporarily symmetrical altered bite position.

scholarly journals Temporomandibular Disorders Do Not Correlate with Detectable Alterations in Body Posture

2007 ◽  
Vol 8 (5) ◽  
pp. 60-67 ◽  
Author(s):  
Giuseppe Perinetti
Keyword(s):  
Temporomandibular Disorders ◽  
Matched Control ◽  
Body Posture ◽  
Dental Occlusion ◽  
Experimental Conditions ◽  
Eyes Closed ◽  
Rest Position ◽  
Eyes Open ◽  
Absolute Centre ◽  
Asymptomatic Subjects

Abstract Aim This study aimed to determine if temporomandibular disorders (TMD) correlate with alterations in body posture detectable through posturography. Methods and Materials Thirty-five asymptomatic subjects and 35 TMD patients (34 males and 36 females; mean age, 27.7±8.6 years) constituted the matched control and TMD groups, respectively. Posturography was performed under four different experimental conditions: (a) eyes open with mandibular rest position (Eyes Open RP); (b) eyes open with dental occlusion (Eyes Open DO); (c) eyes closed with mandibular rest position (Eyes Closed RP); and (d) eyes closed with dental occlusion (Eyes Closed DO). The X, Y, and absolute centre of pressure displacements from the projection of a theoretical barycentre and the sway area, sway length, and sway velocity were recorded as static and dynamic posturographic parameters, respectively. Results Generally, no differences were found in any of these parameters between the groups and between the RP and DO within either Eyes Open/Closed conditions. The only differences were found under Eyes Closed as compared to Eyes Open, irrespective of the RP/DO conditions for dynamic and not for static posturographic parameters. Conclusion This study failed to show detectable alterations in body posture in TMD patients. Citation Perinetti G. Temporomandibular Disorders Do Not Correlate with Detectable Alterations in Body Posture. J Contemp Dent Pract 2007 July;(8)5:060-067.

Myoelectric Activity Differences in Three Learning Sessions

2002 ◽  
Vol 16 (2) ◽  
pp. 92-96
Author(s):  
Tiina Ritvanen ◽  
Reijo Koskelo ◽  
Osmo H„nninen
Keyword(s):  
High School Students ◽  
Muscle Activity ◽  
Muscle Tension ◽  
Emg Activity ◽  
Traditional Learning ◽  
Myoelectric Activity ◽  
School Students ◽  
Language Laboratory ◽  
Upper Trapezius ◽  
Muscle Groups

Abstract This study follows muscle activity in three different learning sessions (computer, language laboratory, and normal classroom) while students were studying foreign languages. Myoelectric activity was measured in 21 high school students (10 girls, 11 boys, age range 17-20 years) by surface electromyography (sEMG) from the upper trapezius and frontalis muscles during three 45-min sessions. Root mean square (RMS) average from both investigated muscles was calculated. The EMG activity was highest in both muscle groups in the computer-aided session and lowest in the language laboratory. The girls had higher EMG activity in both investigated muscle groups in all three learning situations. The measured blood pressure was highest at the beginning of the sessions, decreased within 10 min, but increased again toward the end of the sessions. Our results indicate that the use of a computer as a teaching-aid evokes more constant muscle activity than the traditional learning situations. Since muscle tension can have adverse health consequences, more research is needed to determine optimal classroom conditions, especially when technical aids are used in teaching.

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