Static lifting strength and maximal isometric voluntary contractions of back, arm and shoulder muscles

Ergonomics ◽  
1980 ◽  
Vol 23 (1) ◽  
pp. 37-47 ◽  
Author(s):  
J. W. YATES ◽  
E. KAMON ◽  
S. H. RODGERS ◽  
P. C. COMPANY
1981 ◽  
Vol 48 (4) ◽  
pp. 163-168 ◽  
Author(s):  
Anthony R. Newall ◽  
Karen L. Robinson ◽  
Sandi J. Spaulding

Bilateral sanding is used by occupational therapists as a therapeutic exercise technique, however, to-date no data have been available identifying the musculature involved in the activity nor the extent of that involvement. The dual purpose of this pilot study was to; (a) delineate the activity of selected shoulder muscles during bilateral sanding, and (b) determine whether the method used would be feasible in the analysis of other therapeutic activities. For this investigation, a quadriplegic individual was matched for height and weight with a normal subject and both were tested under several controlled conditions of bilateral sanding. Right shoulder complex musculature was electromyographically (EMG) investigated and the muscles studied were: pectoralis major, biceps brachii, the three heads of deltoid, and the lateral and medial heads of triceps brachii. EMG data for the two subjects were normalized and represented as percentages of the maximal voluntary contractions (MVC) relative for each muscle. This technique allowed intra- and inter-subject comparisons of muscle activity. Recognizing the limitations of the study with the major one being the small number of subjects, useful information was obtained from the results. The quadriplegic individual appeared to be more inefficient in his muscle usage than the normal subject. This may be related to trunk instability in the quadriplegic subject. All three heads of the deltoid appeared to be the most highly used of monitored muscles in both the normal and the quadriplegic with triceps being only moderately active in the quadriplegic individual. Spring resisted bilateral sanding produced the most EMG activity in all muscles studied in both subjects. Further investigations employing a larger number of subjects may further elucidate EMG activity during bilateral sanding. It would appear that EMG investigations of therapeutic activities offer an informative method of physical activity analysis.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Dorian Glories ◽  
Mathias Soulhol ◽  
David Amarantini ◽  
Julien Duclay

AbstractDuring voluntary contractions, corticomuscular coherence (CMC) is thought to reflect a mutual interaction between cortical and muscle oscillatory activities, respectively measured by electroencephalography (EEG) and electromyography (EMG). However, it remains unclear whether CMC modulation would depend on the contribution of neural mechanisms acting at the spinal level. To this purpose, modulations of CMC were compared during submaximal isometric, shortening and lengthening contractions of the soleus (SOL) and the medial gastrocnemius (MG) with a concurrent analysis of changes in spinal excitability that may be reduced during lengthening contractions. Submaximal contractions intensity was set at 50% of the maximal SOL EMG activity. CMC was computed in the time–frequency domain between the Cz EEG electrode signal and the unrectified SOL or MG EMG signal. Spinal excitability was quantified through normalized Hoffmann (H) reflex amplitude. The results indicate that beta-band CMC and normalized H-reflex were significantly lower in SOL during lengthening compared with isometric contractions, but were similar in MG for all three muscle contraction types. Collectively, these results highlight an effect of contraction type on beta-band CMC, although it may differ between agonist synergist muscles. These novel findings also provide new evidence that beta-band CMC modulation may involve spinal regulatory mechanisms.


2021 ◽  
pp. 1-11
Author(s):  
Kale Mehmet

BACKGROUND: There is insufficient knowledge about the rate of force development (RFD) characteristics over both single and multiple joint movements and the electromechanical delay (EMD) values obtained in athletes and untrained individuals. OBJECTIVE: To compare single and multiple joint functions and the neural drive of trained athletes and untrained individuals. METHODS: Eight trained athletes and 10 untrained individuals voluntarily participated to the study. The neuromuscular performance was assessed during explosive and maximum voluntary isometric contractions during leg press and knee extension related to single and multiple joint. Explosive force and surface electromyography of eight superficial lower limb muscles were measured in five 50-ms time windows from their onset, and normalized to peak force and electromyography activity at maximum voluntary force, respectively. The EMD was determined from explosive voluntary contractions (EVC’s). RESULTS: The results showed that there were significant differences in absolute forces during knee extension maximum voluntary force and EVC’s (p< 0.01) while trained athletes achieved greater relative forces than untrained individuals of EVC at all five time points (p< 0.05). CONCLUSIONS: The differences in explosive performance between trained athletes and untrained individuals in both movements may be explained by different levels of muscle activation within groups, attributed to variation in biarticular muscle function over both activities.


2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Daniel Kadlec ◽  
Matthew J. Jordan ◽  
Leanne Snyder ◽  
Jacqueline Alderson ◽  
Sophia Nimphius

Abstract Purpose To examine the test re-test reliability of isometric maximal voluntary contractions (MVC) of hip adduction (ADDISO), hip abduction (ABDISO), and multijoint leg extension (SQUATISO) in sub-elite female Australian footballers. Methods Data were collected from 24 sub-elite female Australian footballers (age 22.6 ± 4.5 years; height 169.4 ± 5.5 cm; body mass 66.6 ± 8.0 kg; 4.5 ± 4.4 years sport-specific training; 2.5 ± 2.0 years unstructured resistance training) from the same club on two non-consecutive days. Participants performed three isometric MVCs of ADDISO, ABDISO, and SQUATISO. The SQUATISO was performed at 140° knee flexion with a vertical trunk position and ADDISO and ABDISO measures were performed in a supine position at 60° of knee flexion and 60° hip flexion. Reliability was assessed using paired t tests and the intraclass correlation coefficient (ICC) with 95% confidence intervals (CI), typical error (TE), and coefficient of variation (CV%) with 95% CI. Results SQUATISO peak force (ICC .95; CV% 4.1), ABDISO for left, right, and sum (ICC .90–.92; CV% 5.0–5.7), and ADDISO for left, right, and sum (ICC .86–.91; CV% 6.2–6.9) were deemed acceptably reliable based on predetermined criteria (ICC ≥ .8 and CV% ≤ 10). Conclusion SQUATISO, ABDISO, and ADDISO tests demonstrated acceptable reliability for the assessment of peak force in sub-elite female Australian footballers, suggesting these assessments are suitable for muscle strength testing and monitoring adaptations to training.


2021 ◽  
Vol 11 (5) ◽  
pp. 2035
Author(s):  
Joseph Mizrahi

A combination of factors exposes musicians to neuro-musculoskeletal disorders, which lead to pain and damage. These involve overuse due to long playing hours, containing repetitive movements under stressful conditions, usually performed in an unnatural posture. Although the evoked disorders are usually non-traumatic, they may often lead to prolonged or even permanent damage. For instance, in upper string players, these include bursitis and tendinopathies of the shoulder muscles, tendonitis of the rotator cuff, injury at the tendon sheaths, medial or lateral epicondylitis (also known as tennis elbow), myofascial pain, and wrist tendonitis (also known as carpal tunnel syndrome, or De Quervein’s syndrome). In cases of intensive performance, a traumatic injury may result, requiring drastic means of intervention such as surgery. It should be pointed out that the upper body and upper extremities are the most commonly affected sites of playing musicians. This review provides a description of the playing-related motor disorders in performing musicians, and of the methodologies used to identify and evaluate these disorders, particularly for violinists and other upper string players.


2020 ◽  
pp. 1-13
Author(s):  
Luigi Catino ◽  
Chiara Malloggi ◽  
Stefano Scarano ◽  
Valeria Cerina ◽  
Viviana Rota ◽  
...  

BACKGROUND: A method of measurement of voluntary activation (VA, percent of full muscle recruitment) during isometric and isokinetic concentric contractions of the quadriceps femoris (QF) at 60∘/s and 120∘/s was previously validated. OBJECTIVE: This study aimed to quantify the test-retest minimal real difference (MRD) of VA during isometric (ISOM) and isokinetic concentric contractions of QF (100∘/s, ISOK) in a sample of healthy individuals. METHODS: VA was measured through the interpolated twitch technique. Pairs of electrical stimuli were delivered to the QF at 40∘ of knee flexion during maximal voluntary contractions. Twenty-five healthy participants (20–38 years, 12 women, 13 men) completed two testing sessions with a 14-day interval. VA values were linearized through logit transformation (VAl). The MRD was estimated from intraclass correlation coefficients (model 2.1). RESULTS: The VA (median, range) was 84.20% (38.2–99.9%) in ISOM and 94.22% (33.8-100%) in ISOK. MRD was 0.78 and 1.12 logit for ISOM and ISOK, respectively. As an example, in terms of percent VA these values correspond to a change from 76% to 95% and from 79% to 98% in ISOM and in ISOK, respectively. CONCLUSIONS: The provided MRD values allow to detect significant individual changes in VA, as expected after training and rehabilitation programs.


2014 ◽  
Vol 39 (12) ◽  
pp. 1338-1344 ◽  
Author(s):  
Israel Halperin ◽  
David Copithorne ◽  
David G. Behm

Nonlocal muscle fatigue occurs when fatiguing 1 muscle alters performance of another rested muscle. The purpose of the study was to investigate if fatiguing 2 separate muscles would affect the same rested muscle, and if fatiguing the same muscle would affect 2 separate muscles. Twenty-one trained males participated in 2 studies (n = 11; n = 10). Subjects performed 2 pre-test maximum voluntary contractions (MVCs) with the nondominant knee extensors. Thereafter they performed two 100-s MVCs with their dominant knee extensors, elbow flexors, or rested. Between and after the sets, a single MVC with the nondominant rested knee extensors was performed. Subsequently, 12 nondominant knee extensors repeated MVCs were completed. Force, quadriceps voluntary activation (VA), and electromyography (EMG) were measured. The same protocol was employed in study 2 except the nondominant elbow-flexors were tested. Study 1: Compared with control conditions, a significant decrease in nondominant knee extensors force, EMG, and VA was found under both fatiguing conditions (P ≤ 0.05; effect size (ES) = 0.91–1.15; 2%–8%). Additionally, decrements in all variables were found from the first post-intervention MVC to the last (P ≤ 0.05; ES = 0.82–2.40; 9%–20%). Study 2: No differences were found between conditions for all variables (P ≥ 0.33; ES ≤ 0.2; ≤3.0%). However, all variables decreased from the first post-intervention MVC to the last (P ≤ 0.05; ES = 0.4–3.0; 7.2%–19.7%). Whereas the rested knee extensors demonstrated nonlocal effects regardless of the muscle being fatigued, the elbow-flexors remained unaffected. This suggests that nonlocal effects are muscle specific, which may hold functional implications for training and performance.


2016 ◽  
Vol 9 (2) ◽  
pp. 112-126 ◽  
Author(s):  
Rita Kinsella ◽  
Tania Pizzari

Background Subacromial pain syndrome (SPS) is a common cause of shoulder pain and muscle activity deficits are postulated to contribute to the development and progression of the disorder. The purpose of this systematic review was to definitively determine whether evidence exists of differences in electromyography (EMG) characteristics between subjects with and without SPS. Methods Six key databases were searched: MEDLINE, EMBASE, CINAHL, SPORTdiscus, PEDro and The Cochrane Library (inception to May 2016). The search yielded 1414 records using terms relating to shoulder impingement, EMG, scapular and rotator cuff muscles. Twenty-two papers remained once duplicates were removed and selection criteria applied. Data extraction, quality assessment and data synthesis were performed. Effect sizes and 95% confidence intervals were calculated. Results There was limited evidence that serratus anterior has lower amplitude, delayed activation and earlier termination in SPS participants. For the majority of muscles, regardless of task, load or arm position, significant differences were not demonstrated or results were contradictory. Conclusions The understanding of SPS is changing and EMG appears unable to capture the complexities associated with this condition. Addressing aberrant movement patterns and facilitating balanced activation of all shoulder muscles may be a more appropriate treatment direction for the future.


2003 ◽  
Vol 41 (2) ◽  
pp. 198-202 ◽  
Author(s):  
M. Watakabe ◽  
K. Mita ◽  
K. Akataki ◽  
K. Ito

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