scholarly journals Quantifying Topographical Changes in Muscle Activation: A Statistical Parametric Mapping Approach

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 71
Author(s):  
Patricio A. Pincheira ◽  
Eduardo Martinez-Valdes ◽  
Carlos De la Fuente ◽  
Felipe Palma ◽  
Oscar Valencia ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Muscle Activation ◽  
Plantar Flexion ◽  
Statistical Parametric Mapping ◽  
High Sensitivity ◽  
Voluntary Contraction ◽  
Medial Gastrocnemius ◽  
Isometric Contractions ◽  
Parametric Mapping ◽  
Repeated Measures Anova

Regional changes in muscle activation occur at different contraction intensities. These changes can be observed with activity maps created with high-density electromyography (HDEMG). When quantifying these changes, statistical parametric mapping (SPM) is a neuroimaging technique that may be used to perform statistical analyses with high sensitivity and spatial resolution. The aim of this study was to identify regional changes in muscle activation at different contraction intensities, comparing SPM and the HDEMG barycenter (centroid). Twelve participants performed plantar flexion isometric contractions at 20%, 40%, and 60% of the maximal voluntary contraction (MVC), while HDEMG was recorded from the medial gastrocnemius. An SPM repeated measures ANOVA design revealed specific mediolateral and cephalocaudal changes in muscle activation with increasing contraction intensities, which were not clearly detected by the variation in the barycenter coordinates. Only SPM revealed statistically significant nonuniform changes in EMG amplitude between all increasing levels of muscle activation.

scholarly journals Different Shoulder Exercises Affect the Activation of Deltoid Portions in Resistance-Trained Individuals

2020 ◽  
Vol 75 (1) ◽  
pp. 5-14
Author(s):  
Yuri A. C. Campos ◽  
Jeferson M. Vianna ◽  
Miller P. Guimarães ◽  
Jorge L. D. Oliveira ◽  
Claudio Hernández-Mosqueira ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Muscle Activation ◽  
Bench Press ◽  
Voluntary Contraction ◽  
Data Normalization ◽  
Significance Level ◽  
Repeated Measures Anova ◽  
Level Of Activity ◽  
Significant Difference ◽  
Anterior Deltoid

Abstract The aims of this study were to compare muscle activity of the anterior deltoid, medial deltoid, and posterior deltoid in the bench press, dumbbell fly, shoulder press, and lateral raise exercises. Thirteen men experienced in strength training volunteered for the study. Muscle activation was recorded during maximum isometric voluntary contraction (MVIC) for data normalization, and during one set of 12 repetitions with the load of 60% 1RM in all exercises proposed. One-way repeated-measures ANOVA with Bonferroni’s posthoc was applied using a 5% significance level. For anterior deltoid, the shoulder press (33.3% MVIC) presented a significantly higher level of activation when compared to other exercises. Also, no significant difference was found between the bench press (21.4% MVIC), lateral raise (21.2% MVIC), and dumbbell fly (18.8% MVIC). For the medial deltoid, the lateral raise (30.3% MVIC) and shoulder press (27.9% MVIC) presented a significantly higher level of activity than the bench press (5% MVIC) and dumbbell fly (3.4% MVIC). Besides, no significant difference was found between the bench press and the dumbbell fly. For the posterior deltoid, the lateral raise (24% MVIC) presented a significantly higher level of activation when compared to other exercises. For the posterior deltoid portion, the shoulder press (11.4% MVIC) was significantly more active than the bench press (3.5% MVIC) and dumbbell fly (2.5% MVIC). Moreover, no significant difference was found between the bench press and the dumbbell fly. In conclusion, the shoulder press and lateral raise exercises showed a higher level of muscle activation in the anterior deltoid and medial deltoid when compared to the bench press and dumbbell fly exercises.

scholarly journals Role of Occupational Footwear and Prolonged Walking on Lower Extremity Muscle Activation during Maximal Exertions and Postural Stability Tasks

Biomechanics ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 202-213
Author(s):  
Harish Chander ◽  
Sachini N. K. Kodithuwakku Arachchige ◽  
Alana J. Turner ◽  
Reuben F. Burch V ◽  
Adam C. Knight ◽  
...  
Keyword(s):  
Lower Extremity ◽  
Muscle Activity ◽  
Repeated Measures ◽  
Postural Stability ◽  
Muscle Activation ◽  
Medial Gastrocnemius ◽  
Lower Extremity Muscle ◽  
Prolonged Duration ◽  
The Mean ◽  
The Impact

Background: Occupational footwear and a prolonged duration of walking have been previously reported to play a role in maintaining postural stability. The purpose of this paper was to analyze the impact of three types of occupational footwear: the steel-toed work boot (ST), the tactical work boot (TB), and the low-top work shoe (LT) on previously unreported lower extremity muscle activity during postural stability tasks. Methods: Electromyography (EMG) muscle activity was measured from four lower extremity muscles (vastus medialis (VM), medial hamstrings (MH), tibialis anterior (TA), and medial gastrocnemius (MG) during maximal voluntary isometric contractions (MVIC) and during a sensory organization test (SOT) every 30 min over a 4 h simulated workload while wearing ST, TB, and LT footwear. The mean MVIC and the mean and percentage MVIC during each SOT condition from each muscle was analyzed individually using a repeated measures ANOVA at an alpha level of 0.05. Results: Significant differences (p < 0.05) were found for maximal exertions, but this was limited to only the time main effect. No significant differences existed for EMG measures during the SOT. Conclusion: The findings suggest that occupational footwear type does not influence lower extremity muscle activity during both MVIC and SOT. Significantly lower muscle activity during maximal exertions over the course of the 4 h workload was evident, which can be attributed to localized muscular fatigue, but this was not sufficient to impact muscle activity during postural stability tasks.

scholarly journals Influence of static stretching on viscoelastic properties of human tendon structures in vivo

2001 ◽  
Vol 90 (2) ◽  
pp. 520-527 ◽  
Author(s):  
Keitaro Kubo ◽  
Hiroaki Kanehisa ◽  
Yasuo Kawakami ◽  
Tetsuo Fukunaga
Keyword(s):  
Viscoelastic Properties ◽  
Plantar Flexion ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Medial Gastrocnemius ◽  
Static Stretching ◽  
Tendon Elongation ◽  
Before And After ◽  
Human Tendon

The purpose of this study was to investigate the influences of static stretching on the viscoelastic properties of human tendon structures in vivo. Seven male subjects performed static stretching in which the ankle was passively flexed to 35° of dorsiflexion and remained stationary for 10 min. Before and after the stretching, the elongation of the tendon and aponeurosis of medial gastrocnemius muscle (MG) was directly measured by ultrasonography while the subjects performed ramp isometric plantar flexion up to the maximum voluntary contraction (MVC), followed by a ramp relaxation. The relationship between the estimated muscle force (Fm) of MG and tendon elongation ( L) during the ascending phase was fitted to a linear regression, the slope of which was defined as stiffness of the tendon structures. The percentage of the area within the Fm- L loop to the area beneath the curve during the ascending phase was calculated as an index representing hysteresis. Stretching produced no significant change in MVC but significantly decreased stiffness and hysteresis from 22.9 ± 5.8 to 20.6 ± 4.6 N/mm and from 20.6 ± 8.8 to 13.5 ± 7.6%, respectively. The present results suggest that stretching decreased the viscosity of tendon structures but increased the elasticity.

The Effect of Fatigue on Leg Muscle Activation and Tibial Acceleration During a Jumping Task

2020 ◽  
Vol 29 (8) ◽  
pp. 1093-1099
Author(s):  
Michelle A. Sandrey ◽  
Yu-Jen Chang ◽  
Jean L. McCrory
Keyword(s):  
Lower Extremity ◽  
Athletic Training ◽  
Repeated Measures ◽  
Tibialis Anterior ◽  
Muscle Activation ◽  
Vertical Jump ◽  
Medial Gastrocnemius ◽  
History Of ◽  
Linear Envelope ◽  
And Control

Context: Lower-extremity stress fractures (SFx) are a common occurrence during load-bearing activities of jumping and landing. To detect biomechanical changes during jumping postinjury, a fatigue model could be used. Objective: To evaluate muscle activation in the lower leg and tibial accelerations (TAs) prefatigue to postfatigue following a jumping task in those with and without a history of SFx. Design: Repeated-measures. Setting: Athletic Training Research Lab. Participants: A total of 30 active college-aged students with and without a history of lower-extremity (leg or foot) SFx (15 males and 15 females; 21.5 [5.04] y, height = 173.5 [12.7] cm, weight = 72.65 [16.4] kg). Intervention: A maximal vertical jump on one leg 3 times with arms folded across the chest prefatigue to postfatigue was performed. Fatigue protocol was standing heel raises on a custom-built platform at a pace controlled by a metronome until task failure was reached. Legs were tested using a randomized testing order. Electromyographic (EMG) surface electrodes were placed on the medial gastrocnemius, soleus, and tibialis anterior following a standardized placement protocol. A triaxial accelerometer was attached to the proximal anteromedial surface of the tibia. Main Outcome Measures: Linear envelopes of the medial gastrocnemius, soleus, and tibialis anterior and peak accelerations (resultant acceleration takeoff and landing). Results: Significant interaction for leg × test for tibialis anterior with a posttest difference between SFx and control (P = .05). There were decreases in EMG linear envelope following fatigue for medial gastrocnemius (P < .01) and tibialis anterior (P = .12) pretest to posttest. At takeoff, TA was greater in the SFx contralateral leg in comparison with the control leg (P = .04). At landing, TA was greater in posttest (P < .01) and in the SFx leg compared with SFx contralateral (P = .14). Conclusion: A decrease in muscle activity and an increase in TA following fatigue were noted for all subjects but especially for those with a history of SFx.

scholarly journals Lower Extremity Muscle Activation in Alternative Footwear during Stance Phase of Slip Events

2021 ◽  
Vol 18 (4) ◽  
pp. 1533
Author(s):  
Harish Chander ◽  
John C. Garner ◽  
Chip Wade ◽  
Adam C. Knight
Keyword(s):  
Lower Extremity ◽  
Muscle Activity ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Stance Phase ◽  
Voluntary Contraction ◽  
Repeated Measures Design ◽  
Lower Extremity Muscle ◽  
Repeated Measures Analysis ◽  
The Impact

Muscle activity from the slipping leg have been previously used to analyze slip induced falls. However, the impact of casual alternative footwear on slipping leg muscle activity when exposed to slippery environments is still unknown. The purpose of the study was to analyze the impact of alternative footwear (crocs (CC) and flip-flops (FF)) compared to slip-resistant footwear (LT) on lower extremity muscle activity when exposed to dry gait (NG), unexpected (US), alert (AS), and expected slips (ES). Eighteen healthy males (age: 22.3 ± 2.2 years; height: 177.7 ± 6.9 cm; weight: 79.3 ± 7.6 kg) completed the study in a repeated measures design in three footwear sessions separated by 48 h. Electromyography (EMG) muscle activity from four muscles of the lead/slipping leg was measured during the stance phase of the gait-slip trials. A 3 (footwear) × 4 (gait-slip trials) repeated measures analysis of variance was used to analyze EMG dependent variables mean, peak, and percent of maximal voluntary contraction. Greater lower extremity muscle activation during the stance phase was seen in US and AS conditions compared to NG and ES. In addition, footwear differences were seen for the alternative footwear (CC and FF) during US and AS, while the low top slip resistant shoe had no differences across all gait trials, suggesting it as the most efficient footwear of choice, especially when maneuvering slippery flooring conditions, either with or without the knowledge of an impending slip.

Alternate activity in the synergistic muscles during prolonged low-level contractions

1998 ◽  
Vol 84 (6) ◽  
pp. 1943-1951 ◽  
Author(s):  
H. Tamaki ◽  
K. Kitada ◽  
T. Akamine ◽  
F. Murata ◽  
T. Sakou ◽  
...  
Keyword(s):  
Time Course ◽  
Human Subjects ◽  
Plantar Flexion ◽  
Constant Load ◽  
Voluntary Contraction ◽  
Medial Gastrocnemius ◽  
Lateral Gastrocnemius ◽  
Low Level ◽  
Synergistic Muscles ◽  
Synergistic Muscle

The purpose of this study was to investigate the functional interrelationship between synergistic muscle activities during low-level fatiguing contractions. Six human subjects performed static and dynamic contractions at an ankle joint angle of 110° plantar flexion and within the range of 90–110° (anatomic position = 90°) under constant load (10% maximal voluntary contraction) for 210 min. Surface electromyogram records from lateral gastrocnemius (LG), medial gastrocnemius (MG), and soleus (Sol) muscles showed high and silent activities alternately in the three muscles and a complementary and alternate activity between muscles in the time course. In the second half of all exercise times, the number of changes in activity increased significantly ( P < 0.05) in each muscle. The ratios of active to silent periods of electromyogram activity were significantly higher ( P< 0.05) in MG (4.5 ± 2.2) and Sol (4.3 ± 2.8) than in the LG (0.4 ± 0.1), but no significant differences were observed between MG and Sol. These results suggest that the relative activation of synergistic motor pools are not constant during a low-level fatiguing task.

scholarly journals Gluteus Medius Muscle Activation During Isometric Muscle Contractions

2011 ◽  
Vol 20 (2) ◽  
pp. 174-186 ◽  
Author(s):  
Catriona O’Dwyer ◽  
David Sainsbury ◽  
Kieran O’Sullivan
Keyword(s):  
Internal Rotation ◽  
Outcome Measures ◽  
Lower Limb ◽  
Repeated Measures ◽  
Muscle Activation ◽  
External Rotation ◽  
Gluteus Medius ◽  
Isometric Contractions ◽  
Main Effect

Context:Functional subdivisions are proposed to exist in the gluteus medius (GM) muscle. Dysfunction of the GM, in particular its functional subdivisions, is commonly implicated in lower limb pathologies. However, there is a lack of empirical evidence examining the role of the subdivisions of the GM.Objectives:To compare the activation of the functional subdivisions of the GM (anterior, middle, and posterior) during isometric hip contractions.Design:Single-session, repeated-measures observational study.Setting:University research laboratory.Participants:Convenience sample of 15 healthy, pain-free subjects.Intervention:Subjects performed 3 maximal voluntary isometric contractions for hip abduction and internal and external rotation on an isokinetic dynamometer with simultaneous recording of surface electromyography (sEMG) activity of the GM subdivisions.Main Outcome Measures:sEMG muscle activity for each functional subdivision of the GM during each hip movement was analyzed using a 1-way repeated-measures ANOVA (post hoc Bonferroni).Results:The response of GM subdivisions during the 3 different isometric contractions was significantly different (interaction effect; P = .003). The anterior GM displayed significantly higher activation across all 3 isometric contractions than the middle and posterior subdivisions (main effect; both P < .001). The middle GM also demonstrated significantly higher activation than the posterior GM across all 3 isometric contractions (main effect; P = .027). There was also significantly higher activation of all 3 subdivisions during both abduction and internal rotation than during external rotation (main effect; both P < .001).Conclusions:The existence of functional subdivisions in the GM appears to be supported by the findings. Muscle activation was not homogeneous throughout the entire muscle. The highest GM activation was found in the anterior GM subdivision and during abduction and internal rotation. Future studies should examine the role of GM functional subdivisions in subjects with lower limb pathologies.

scholarly journals Muscle activation in specific regions of the trapezius during modified Kendall manual muscle tests

2021 ◽  
Author(s):  
Zachariah J. Henderson ◽  
Sarah Bohunicky ◽  
Josee A. Rochon ◽  
Mark Dacanay ◽  
Trisha D. Scribbans
Keyword(s):  
Repeated Measures ◽  
Muscle Activation ◽  
The Other ◽  
Muscle Fibres ◽  
Isometric Contractions ◽  
Mean Square ◽  
Healthy Individuals ◽  
Maximal Contraction ◽  
Density Surface ◽  
Shoulder Pathologies

Abstract Context: Manual muscle tests (MMTs) are often used when assessing shoulder pathologies. For the trapezius, individual MMTs are used to selectively test the upper (UTR), middle (MTR), and lower (LTR) trapezius regions. It is assumed that MMTs for each region preferentially recruit the corresponding muscle fibres and produce a “maximal” contraction; however, it is unknown if this is true. Objective: To determine if maximum voluntary isometric contractions (MVICs) for the upper (UT-MVIC), middle (MT-MVIC), and lower (LT-MVIC) trapezius, adapted from the Kendall MMTs, recruit the corresponding trapezius regions. Design: Cross-Over. Setting: Laboratory. Participants: 20 young, healthy individuals. Intervention: Participants performed three repetitions of each MVIC. High density surface electromyography was collected from the UTR, MTR, and LTR. Main Outcome Measures: Root mean square (excitation) of the UTR, MTR, and LTR. Statistical Analysis: Three, one-way repeated measures ANOVAs. Results: UTR excitation: There was a significant increase in UTR excitation during the LT-MVIC compared to the UT-MVIC (p = .016), and MT-MVIC (p &lt; .001). MTR excitation: There was a significant increase in MTR excitation during the MT-MVIC compared to the UT-MVIC (p = .001), and a significant increase in MTR excitation during the LT-MVIC compared to the UT-MVIC (p &lt; .001). There was also a significant increase in MTR excitation during the LT-MVIC compared to the MT-MVIC (p &lt; .001). LTR excitation: There was a significant increase in LTR excitation during the MT-MVIC (p &lt; .001) and LT-MVIC (p &lt; .001) compared to the UT-MVIC. Conclusions: The UT-MVIC and MT-MVIC do not necessarily recruit the corresponding trapezius regions more than the other MVICs. Rather, the LT-MVIC appears to produce the greatest excitation in all trapezius regions. Additional research is needed; however, clinicians should be aware that maximal contractions may not always recruit the desired musculature when forming a clinical interpretation.

More than a footwedge: Golf-specific footwear alters muscle activation patterns during standing balance

2020 ◽  
pp. 175433712093826
Author(s):  
Samuel J Wilson ◽  
Jacob R Gdovin ◽  
Charles C Williams ◽  
Paul T Donahue ◽  
James G Mouser ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Repeated Measures ◽  
Muscle Activation ◽  
Activity Patterns ◽  
Standing Balance ◽  
Medial Gastrocnemius ◽  
Extrinsic Factors ◽  
Activation Patterns ◽  
Intrinsic Factors ◽  
Muscle Activation Patterns

Within a golf swing, one aspect that stands out in each phase is the ability to maintain balance. Previous reports suggest that extrinsic factors, such as footwear, and intrinsic factors, such as muscular exertion level, have detrimental effects on human postural control. However, no studies have examined the effects of modern golf footwear on muscle activity of the lower extremity. Thus, the purpose of this study was to examine differences in muscle activity when walking for extended durations in golf footwear. Participants were tested for balance prior to walking sessions and then every 60 min until the 240th minute in three types of golf footwear; dress shoes, tennis shoes, and casual shoes, and barefoot. Mean muscle activity during balance testing of the vastus medialis, semitendinosus, tibialis anterior, and medial gastrocnemius was examined using a 4 × 5 repeated measures analysis of variance to identify differences within time and footwear types. Increases in muscle activity were observed after the second hour. Footwear differences were observed in the dress shoe and tennis shoe style relative to the casual style, and primarily attributed to the increased sole/midsole thickness, and increased mass of the dress shoe. These results suggest that golf footwear characteristics may alter muscle activity patterns during standing balance.

scholarly journals Importance of Maximal Strength and Muscle-Tendon Mechanics for Improving Force Steadiness in Persons with Parkinson’s Disease

2020 ◽  
Vol 10 (8) ◽  
pp. 471
Author(s):  
Rowan R. Smart ◽  
Cydney M. Richardson ◽  
Daryl J. Wile ◽  
Brian H. Dalton ◽  
Jennifer M. Jakobi
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Plantar Flexion ◽  
Voluntary Contraction ◽  
Medial Gastrocnemius ◽  
Force Steadiness ◽  
Tracking Tasks ◽  
Tendon Mechanics ◽  
Tendon Elongation ◽  
Underlying Causes

Although plantar flexion force steadiness (FS) is reduced in persons with Parkinson’s disease (PD), the underlying causes are unknown. The aim of this exploratory design study was to ascertain the influence of maximal voluntary contraction (MVC) force and gastrocnemius-Achilles muscle-tendon unit behaviour on FS in persons with PD. Nine persons with PD and nine age- and sex-matched non-PD controls (~70 years, 6 females per group) performed plantar flexion MVCs and sub-maximal tracking tasks at 5, 10, 25, 50 and 75% MVC. Achilles tendon elongation and medial gastrocnemius fascicle lengths were recorded via ultrasound during contraction. FS was quantified using the coefficient of variation (CV) of force. Contributions of MVC and tendon mechanics to FS were determined using multiple regression analyses. Persons with PD were 35% weaker during MVC (p = 0.04) and had 97% greater CV (p = 0.01) with 47% less fascicle shortening (p = 0.004) and 38% less tendon elongation (p = 0.002) than controls. Reduced strength was a direct contributor to lower FS in PD (ß = 0.631), and an indirect factor through limiting optimal muscle-tendon unit interaction. Interestingly, our findings indicate an uncoupling between fascicle shortening and tendon elongation in persons with PD. To better understand limitations in FS and muscle-tendon unit behavior, it is imperative to identify the origins of MVC decrements in persons with PD.

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