scholarly journals Heterogeneity of muscle activity during sedentary behavior

2016 ◽  
Vol 41 (11) ◽  
pp. 1155-1162 ◽  
Author(s):  
Arto J. Pesola ◽  
Arto Laukkanen ◽  
Olli Tikkanen ◽  
Taija Finni
Keyword(s):  
Health Risks ◽  
Muscle Activity ◽  
Knee Extension ◽  
Normal Weight ◽  
Emg Activity ◽  
Hamstring Muscle ◽  
Emg Amplitude ◽  
Isometric Knee Extension ◽  
The Individual ◽  
Muscle Inactivity

Replacing sitting by standing has been hypothesized to reduce the health risks of sitting, based on the assumption that muscles are passive during sitting and active during standing. Interventions have been more effective in overweight (OW) than in normal weight (NW) individuals, but subjects’ muscle activities have not been quantified. This study compared quadriceps and hamstring muscle electromyographic (EMG) activity between 57 NW (body mass index (BMI) 22.5 ± 1.5 kg/m2, female n = 36) and 27 OW (BMI 28.4 ± 2.9 kg/m2, female n = 8) subjects during non-fatiguing standing (15 s, EMGstanding) and sitting (30 min). EMG amplitude was normalized to EMG measured during maximal isometric knee extension and flexion (% EMGMVC), and sitting muscle inactivity and bursts were determined using 4 thresholds (60% or 90% EMGstanding and 1% or 2% EMGMVC). Comparisons were adjusted for sex, age, knee extension strength, and the individual threshold. Standing EMG amplitude was 36% higher in OW (1.9% ± 1.5% EMGMVC) than in NW (1.4% ± 1.4% EMGMVC, P < 0.05) subjects. During sitting, muscles were inactive 89.8% ± 12.7% of the measurement time with 12.7 ± 14.2 bursts/min across all thresholds. On average, 6% more activity was recorded in NW than in OW individuals for 3 of the 4 thresholds (P < 0.05 for 60% or 90% EMGstanding and 1% EMGMVC). In conclusion, the OW group had higher muscle activity amplitude during standing but more muscle inactivity during sitting for 3/4 of the thresholds tested. Interventions should test whether the observed heterogeneity in muscle activity affects the potential to gain cardiometabolic benefits from replacing sitting with standing.

scholarly journals Knee Joint Movements in Subjects Without Knee Pathology and Subjects With Injured Anterior Cruciate Ligaments

2002 ◽  
Vol 82 (10) ◽  
pp. 960-972 ◽  
Author(s):  
John H Hollman ◽  
Robert H Deusinger ◽  
Linda R Van Dillen ◽  
Matthew J Matava
Keyword(s):  
Knee Joint ◽  
Muscle Activity ◽  
Mixed Model ◽  
Weight Bearing ◽  
Knee Extension ◽  
Joint Surface ◽  
Emg Activity ◽  
Hamstring Muscle ◽  
Anterior Cruciate ◽  
Knee Pathology

Abstract Background and Purpose. Although weight-bearing (WB) exercise and increased hamstring muscle activity may contribute to knee joint stability in knees with an injured anterior cruciate ligament (ACL), the relationship among ACL integrity, muscle activity, and joint surface motion is not fully understood. The purpose of this study was to investigate whether knee joint rolling and gliding movements and electromyographic (EMG) activity differed between subjects with injured ACLs and subjects without knee pathology. Subjects. Fifteen subjects with injured ACLs (9 men and 6 women; mean age=26 years, SD=7, range=18–36) and 15 age- and sex-matched subjects without knee pathology (9 men and 6 women; mean age=25 years, SD=6, range=18–36) participated in the study. Methods. Sagittal-plane knee joint rolling and gliding movements and lower-extremity EMG activity were measured during non-weight-bearing (NWB) and WB movements. Mixed-model analyses of variance were conducted to analyze rolling and gliding and EMG data. Results. During NWB knee extension, greater joint surface gliding occurred in knees with injured ACLs at full knee extension. During WB knee extension, greater gliding occurred in knees with injured ACLs throughout the range of motion tested. No differences in EMG activity occurred between groups. Discussion and Conclusion. The results suggest that, in the absence of increased hamstring muscle activity, anterior tibial displacement is not reduced in knees with injured ACLs during WB movement.

scholarly journals The Effect of Limb Position on a Static Knee Extension Task can be Explained with a Simple Spinal Cord Circuit Model

2021 ◽  
Author(s):  
Gareth James Richard York ◽  
Hugh Osborne ◽  
Piyanee Sriya ◽  
Sarah Astill ◽  
Marc de Kamps ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Muscle Activity ◽  
Neural Circuits ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Afferent Input ◽  
Muscle Synergy ◽  
Knee Angle ◽  
Activation Patterns ◽  
Isometric Knee Extension

The influence of proprioceptive feedback on muscle activity during isometric tasks is the subject of conflicting studies. We performed an isometric knee extension task experiment based on two common clinical tests for mobility and flexibility. The task was carried out at four pre-set angles of the knee and we recorded from five muscles for two different hip positions. We applied muscle synergy analysis using non-negative matrix factorisation on surface electromyograph recordings to identify patterns in the data which changed with internal knee angle, suggesting a link between proprioception and muscle activity. We hypothesised that such patterns arise from the way proprioceptive and cortical signals are integrated in neural circuits of the spinal cord. Using the MIIND neural simulation platform, we developed a computational model based on current understanding of spinal circuits with an adjustable afferent input. The model produces the same synergy trends as observed in the data, driven by changes in the afferent input. In order to match the activation patterns from each knee angle and position of the experiment, the model predicts the need for three distinct inputs: two to control a non-linear bias towards the extensors and against the flexors, and a further input to control additional inhibition of rectus femoris. The results show that proprioception may be involved in modulating muscle synergies encoded in cortical or spinal neural circuits.

Tibiofemoral Joint-Surface Motions in Weight-Bearing and Non-Weight-Bearing Movement

2003 ◽  
Vol 12 (2) ◽  
pp. 143-161 ◽  
Author(s):  
John H. Hollman ◽  
Robert H. Deusinger ◽  
Linda R. Van Dillen ◽  
Dequan Zou ◽  
Scott D. Minor ◽  
...  
Keyword(s):  
Outcome Measures ◽  
Muscle Activity ◽  
Repeated Measures ◽  
Weight Bearing ◽  
Knee Extension ◽  
Thigh Muscle ◽  
Joint Surface ◽  
Emg Activity ◽  
Sliding Motion ◽  
Type Design

Context:Analyses of the path of instant center of rotation (PICR) can be used to infer joint-surface rolling and sliding motion (arthrokinematics). Previous PICR research has not quantified arthrokinematics during weight-bearing (WB) movement conditions or studied the association of muscle activity with arthrokinematics.Objective:To examine tibiofemoral arthrokinematics and thigh-muscle EMG during WB and non-weight-bearing (NWB) movement.Design:2 x 9 repeated-measures experiment.Setting:Laboratory.Participants:11 healthy adults (mean age 24 years).Main Outcome Measures:Tibiofemoral percentage rolling arthrokinematics and quadriceps: hamstring EMG activity.Results:WB percentage rolling (76.0% ± 4.7%) exceeded that of NWB (57.5% ± 1.8%) through terminal knee extension (F8,80= 8.99,P< .001). Quadriceps:hamstring EMG ratios accounted for 45.1% and 34.7% of the variance in arthrokinematics throughout the WB and NWB movement conditions, respectively (P< .001).Conclusions:More joint-surface rolling occurs through terminal knee extension during WB movement and is associated with an increase in hamstring activity.

scholarly journals Examining Ankle-Joint Laxity Using 2 Knee Positions and With Simulated Muscle Guarding

2016 ◽  
Vol 51 (2) ◽  
pp. 111-117 ◽  
Author(s):  
Shawn Hanlon ◽  
Jaclyn Caccese ◽  
Christopher A. Knight ◽  
Charles “Buz” Swanik ◽  
Thomas W. Kaminski
Keyword(s):  
Knee Flexion ◽  
Emg Activity ◽  
Complex Motion ◽  
Cross Sectional ◽  
Anterior Drawer ◽  
Anterior Displacement ◽  
Emg Amplitude ◽  
Ankle Complex ◽  
Talar Tilt ◽  
The Individual

 Several factors affect the reliability of the anterior drawer and talar tilt tests, including the individual clinician's experience and skill, ankle and knee positioning, and muscle guarding.Context:  To compare gastrocnemius activity during the measurement of ankle-complex motion at different knee positions, and secondarily, to compare ankle-complex motion during a simulated trial of muscle guarding.Objectives:  Cross-sectional study.Design:  Research laboratory.Setting:  Thirty-three participants aged 20.2 ± 1.7 years were tested.Patients or Other Participants:  The ankle was loaded under 2 test conditions (relaxed, simulated muscle guarding) at 2 knee positions (0°, 90° of flexion) while gastrocnemius electromyography (EMG) activity was recorded.Intervention(s):  Anterior displacement (mm), inversion-eversion motion (°), and peak EMG amplitude values of the gastrocnemius (μV).Main Outcome Measure(s):  Anterior displacement did not differ between the positions of 0° and 90° of knee flexion (P = .193). Inversion-eversion motion was greater at 0° of knee flexion compared with 90° (P &lt; .001). Additionally, peak EMG amplitude of the gastrocnemius was not different between 0° and 90° of knee flexion during anterior displacement (P = .101). As expected, the simulated muscle-guarding trial reduced anterior displacement compared with the relaxed condition (0° of knee flexion, P = .008; 90° of knee flexion, P = .016) and reduced inversion-eversion motion (0° of knee flexion, P = .03; 90° of knee flexion, P &lt; .001).Results:  In a relaxed state, the gastrocnemius muscle did not appear to affect anterior ankle laxity at the 2 most common knee positions for anterior drawer testing; however, talar tilt testing may be best performed with the knee in 0° of knee flexion. Finally, our outcomes from the simulated muscle-guarding condition suggest that clinicians should use caution and be aware of reduced perceived laxity when performing these clinical examination techniques immediately postinjury.Conclusions:

scholarly journals Static vs. Dynamic Acute Stretching Effect on Quadriceps Muscle Activity during Soccer Instep Kicking

2013 ◽  
Vol 39 (1) ◽  
pp. 37-47 ◽  
Author(s):  
Mohammadtaghi Amiri-Khorasani ◽  
Eleftherios Kellis
Keyword(s):  
Angular Velocity ◽  
Muscle Activity ◽  
High Speed ◽  
Muscle Activation ◽  
Body Height ◽  
Rectus Femoris ◽  
Quadriceps Muscle ◽  
Knee Extension ◽  
Emg Activity ◽  
Dynamic Stretching

Abstract The purpose of this study was to compare the effects of static and dynamic stretching on quadriceps muscle activation during maximal soccer instep kicking. The kicking motion of twelve male college soccer players (body height: 174.66 ± 5.01 cm; body mass: 72.83 ± 4.83 kg; age: 18.83 ± 0.75 years) was captured using six synchronized high-speed infra-red cameras whilst electromyography (EMG) signals from vastus medialis (VM), lateralis (VL) and rectus femoris (RF) were recorded before and after static or dynamic stretching. Analysis of variance designs showed a higher increase in knee extension angular velocity (9.65% vs. -1.45%, p < 0.001), RF (37.5% vs. -8.33%, p < 0.001), VM (12% vs. - 12%, p < 0.018), and VL EMG activity (20% vs. -6.67%, p < 0.001) after dynamic stretching exercises. Based on these results, it could be suggested that dynamic stretching is probably more effective in increasing quadriceps muscle activity and knee extension angular velocity during the final swing phase of a maximal soccer instep kick than static stretching.

Influence of Hip Position on Electromyographic and Torque Productions in the Knee

1993 ◽  
Vol 2 (1) ◽  
pp. 26-34 ◽  
Author(s):  
Scott J. Black ◽  
Michael L. Woodhouse ◽  
Stephen Suttmiller ◽  
Larry Shall
Keyword(s):  
Supine Position ◽  
Knee Flexion ◽  
Knee Extension ◽  
Emg Activity ◽  
Sitting Position ◽  
Surface Electrodes ◽  
Recreational Athletes ◽  
Emg Amplitude ◽  
Torque Values ◽  
Flexion And Extension

The effects of hip position on thigh electromyographic (EMG) activity and knee torque were evaluated. Twenty-four recreational athletes (12 males and 12 females) volunteered to participate. Subjects were tested isokinetically at 30°/s in sitting and supine positions both concentrically and eccentrically during knee flexion and extension. Gravity-corrected torques (N·m) were obtained for all tests. EMG amplitude (mV) was collected via surface electrodes. Torque values were significantly greater (p<.05) for knee flexion in the sitting position when compared to the supine. EMG activity did not change relative to hip position but typically increased (p<.05) during concentric trials. Knee extension torque and EMG activity did not change during sitting or supine positions. Results indicated that the sitting position had statistically significant advantages over the supine position for producing greater hamstring torque and maintaining similar levels of EMG output during isokinetic knee flexion.

scholarly journals Impact of glutamatergic and serotonergic neurotransmission on diaphragm muscle activity after cervical spinal hemisection

2017 ◽  
Vol 118 (3) ◽  
pp. 1732-1738 ◽  
Author(s):  
Carlos B. Mantilla ◽  
Heather M. Gransee ◽  
Wen-Zhi Zhan ◽  
Gary C. Sieck
Keyword(s):  
Spinal Cord ◽  
Nmda Receptor ◽  
Muscle Activity ◽  
Spontaneous Recovery ◽  
Cervical Spinal Cord ◽  
Diaphragm Muscle ◽  
Emg Activity ◽  
Emg Amplitude ◽  
Cord Injury ◽  
Phrenic Motoneuron

Incomplete cervical spinal cord hemisection at C2 (SH) disrupts descending excitatory drive to phrenic motoneurons, paralyzing the ipsilateral diaphragm muscle. Spontaneous recovery over time is associated with increased phrenic motoneuron expression of glutamatergic N-methyl-d-aspartate (NMDA) and serotonergic 5-HT2A receptors. We hypothesized that NMDA and 5-HT2A receptor-mediated neurotransmission play a role in ipsilateral diaphragm muscle activity post-SH. Adult male Sprague-Dawley rats were implanted with bilateral diaphragm EMG electrodes for chronic EMG recordings up to 28 days post-SH (SH 28D). The extent of recovery was calculated by peak root-mean-square (RMS) EMG amplitude. In all animals, absence of ipsilateral activity was verified at 3 days post-SH. Diaphragm EMG activity was also recorded during exposure to hypoxia-hypercapnia (10% O2-5% CO2). In SH animals displaying recovery of ipsilateral diaphragm EMG activity at SH 28D, cervical spinal cord segments containing the phrenic motor nucleus (C3–C5) were surgically exposed and either the NMDA receptor antagonist d-2-amino-5-phosphonovalerate (d-AP5; 100 mM, 30 μl) or 5-HT2A receptor antagonist ketanserin (40 mM, 30 μl) was instilled intrathecally. Following d-AP5, diaphragm EMG amplitude was reduced ipsilaterally, during both eupnea (42% of pre-d-AP5 value; P = 0.007) and hypoxia-hypercapnia (31% of pre-d-AP5 value; P = 0.015), with no effect on contralateral EMG activity or in uninjured controls. Treatment with ketanserin did not change ipsilateral or contralateral RMS EMG amplitude in SH animals displaying recovery at SH 28D. Our results suggest that spinal glutamatergic NMDA receptor-mediated neurotransmission plays an important role in ipsilateral diaphragm muscle activity after cervical spinal cord injury. NEW & NOTEWORTHY Spontaneous recovery following C2 spinal hemisection (SH) is associated with increased phrenic motoneuron expression of glutamatergic and serotonergic receptors. In this study, we show that pharmacological inhibition of glutamatergic N-methyl-d-aspartate (NMDA) receptors blunts ipsilateral diaphragm activity post-SH. In contrast, pharmacological inhibition of serotonergic 5-HT2A receptors does not change diaphragm EMG activity post-SH. Our results suggest that NMDA receptor-mediated glutamatergic neurotransmission plays an important role in enhancing rhythmic respiratory-related diaphragm activity after spinal cord injury.

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.

scholarly journals Physical Characteristics Vary According to Body Mass Index in Japanese Community-Dwelling Elderly Women

Geriatrics ◽  
2018 ◽  
Vol 3 (4) ◽  
pp. 87 ◽  
Author(s):  
Koji Nonaka ◽  
Shin Murata ◽  
Kayoko Shiraiwa ◽  
Teppei Abiko ◽  
Hideki Nakano ◽  
...  
Keyword(s):  
Body Mass Index ◽  
Walking Speed ◽  
Elderly Women ◽  
Knee Extension ◽  
Normal Weight ◽  
Physical Characteristics ◽  
Community Dwelling ◽  
Weight Group ◽  
Normal Weight Group ◽  
Knee Extension Strength

Background: Body mass index (BMI) is related to health in the elderly. The purpose of this study was to investigate the physical characteristics in underweight, overweight, and obese Japanese community-dwelling elderly women compared to normal-weight elderly women. Methods: The study participants included 212 community-dwelling elderly women. They were categorized as underweight (BMI < 18.5), normal weight (18.5 ≤ BMI ≤ 22.9), overweight (23 ≤ BMI ≤ 24.9), and obese (BMI ≥ 25). Data on skeletal muscle mass index (SMI), number of trunk curl-ups performed within 30 seconds, knee extension strength, one-leg standing time, and walking speed were recorded. Results: In the underweight group, the number of trunk curl-ups was significantly lower than that of the normal-weight group (p = 0.011) and the correlation between knee extension strength and walking speed was relatively higher than in the normal-weight group (r = 0.612 vs. r = 0.471). In the overweight group, the SMI was significantly increased (p < 0.001), but knee extension strength was not increased (p = 0.235) compared to that of the normal-weight group. In the obese group, one-leg standing time was significantly shorter than in the normal-weight group (p = 0.016). Conclusions: Physical characteristics vary according to BMI and these findings are useful in assessing and planning interventional programs to improve and maintain physical function in elderly women.

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