Illustration of experimental setup, the square wave signal (green tracing), and a typical force signal (white tracing) in the beginning (left) and during the end (right) of the 100 consecutive contractions.

Illustration of experimental setup, the square wave signal (green tracing), and a typical force signal (white tracing) in the beginning (left) and during the end (right) of the 100 consecutive contractions.

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Aim: This study investigates consequences of chronic neck pain on muscle function and the rehabilitating effects of contrasting interventions. Methods: Women with trapezius myalgia (MYA, n = 42) and healthy controls (CON, n = 20) participated in a case-control study. Subsequently MYA were randomized to 10 weeks of specific strength training (SST...

Citations

... Studies assessing the effects of strengthening exercises, [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] ...
Article
Objective: Specific neck exercises targeting deep cervical flexors and extensors are commonly used for the treatment of nonspecific neck pain (NSNP). However, whether specific neck exercises are more effective than alternative exercise interventions remains unclear. Furthermore, it has been postulated that specific neck exercises may be most effective when they are tailored and targeted to patients with evidence of motor control dysfunction, yet this notion also remains unproven. The objectives of this study were to compare the effectiveness of specific neck exercises with that of alternative exercise interventions for reducing pain and disability in people with NSNP and to assess whether the effectiveness of specific neck exercises is increased when the exercises are tailored and provided to patients with evidence of motor control dysfunction. Methods: For this systematic review with meta-analysis, Medline, Web of Science, Scopus, and Physiotherapy Evidence Database were searched. Eligibility criteria included randomized controlled trials evaluating the effectiveness of specific neck exercises against that of alternative exercise interventions in people with NSNP. Meta-analysis included subgroup analyses to determine the effect of exercise tailoring and participant selection criteria on the effectiveness of specific neck exercises. Results: Twelve studies were included. Meta-analysis revealed greater effectiveness of specific neck exercises in the short to medium term for reducing pain (pooled standardized mean difference [SMD] = −0.41; 95% CI = −0.76 to −0.06; P = .02) and disability (pooled SMD = −0.41; 95% CI = −0.78 to −0.04; P = .03) but no differences in the long term for pain (pooled SMD = −1.30; 95% CI = −3.35 to 0.75; P = .21) and disability (pooled SMD = −1.81; 95% CI = −4.29 to 0.67; P = .15), although evidence was limited for the latter. The effectiveness of specific neck exercises was not superior in studies that included only participants with motor control dysfunction or when exercises were tailored to each participant. Overall, the studies were of low quality. Grading of Recommendations Assessment, Development and Evaluation revealed low certainty, serious risk of bias, and inconsistency of findings for short- to medium-term effects and very low certainty, serious risk of bias, and very serious inconsistency for long-term effects. Conclusion: The preferential use of specific neck exercises may be recommended to achieve better short- to medium-term outcomes, although the low quality of evidence affects the certainty of these findings. Currently used strategies for selecting patients and tailoring specific neck exercises are not supported by the evidence and therefore cannot be recommended for clinical practice. Impact: Specific neck exercises are more effective than alternative exercise interventions for reducing pain and disability in patients with nonspecific neck pain in the short to medium term, but overall evidence is of low quality, affecting the certainty of the findings. Tests of muscle dysfunction (mostly the craniocervical flexion test) currently used in studies to select patients and tailor specific neck exercises do not result in greater effectiveness of these exercises. Lay Summary: Evidence suggests specific neck exercises are more effective than other forms of exercise, although evidence is overall of low quality. Use of the craniocervical flexion test in isolation to select participants and/or tailor specific neck exercises can not be recommended.
... Two more studies indicated the same after RT of 8 weeks in young males with a significant increase in muscle endurance during a submaximal task performed till momentary failure (Hong, Hong, and Shin, 2014;Schoenfeld et al., 2019). Increase in fatigue tolerance observed in the present study could be attributed to local muscular factors, such as increased capillarization and myofiber hypertrophy (Andersen et al., 2014) and a shift toward an increased proportion of fatigue-resistant fast-twitch fibers resulting in a more fatigue-resistant muscle fiber profile post-RT (Farup et al., 2014). In addition, RT has also shown to enhance glucose metabolism and increase oxidative enzymes (Groennebaek and Vissing, 2017) and reduce glycolytic muscle enzymes (Tesch, Komi, and Häkkinen, 1987), which might have reduced fatigue in the present experiment. ...
Article
Background Type 2 diabetes mellitus (T2DM) is often accompanied with several neuromuscular complications of which muscle fatigue is one of the scantily studied and less-explored complication of this disease. Objective To investigate the effects of resistance training (RT) on muscle fatigue markers from electromyography (EMG) and capillary blood in T2DM patients. Methods Forty T2DM patients were randomized to either RT (n = 20) or control group (n = 20). They were assessed for EMG indices of muscle fatigue along with blood lactate (at three time points: Lactatepre, Lactatepeak, Lactatepost) during a dynamic fatigue protocol. Dynamic fatigue protocol consisted of 5 sets of leg press exercise at 10 repetition maximum intensity. RT group performed moderate intensity (65%–75% 1 repetition maximum) RT 3 times/week for 12 weeks. Control group followed usual routine. Results Findings revealed that EMG amplitude (root mean square) and Dimitrov’s muscle fatigue index (FInsmk) decreased significantly while median frequency (MF) increased significantly during the dynamic fatigue protocol for both vastus medialis (Root mean square, p = .02; FInsmk, p = .001; MF, p < .001) and vastus lateralis muscle (Root mean square, p= .04,FInsmk,p = .01; MF, p < .001) post-RT. Blood lactate responses did not change after RT (Lactatepre, p = .55; Lactatepeak, p = .91; Lactatepost, p = .33). Conclusions Findings of the present study illustrated that moderate intensity RT led to a significant reduction muscle fatigue in knee extensor muscles of T2DM patients. These results reinforce the utilization of RT in patients with T2DM.
... In the case of physical risk factors, research has consistently shown an association between neck pain and decreased neck muscle strength [11][12][13][14][15][16]. Further, several randomized studies have reported a decrease in neck pain as a result of neck musclestrengthening rehabilitation programs [17][18][19][20]. Similarly, patients with neck pain have shown a decreased cervical range of motion compared with persons without neck pain [11,[21][22][23][24]. ...
Article
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Background Neck pain has been associated with weaker neck muscle strength and decreased cervical spine range of motion. However, whether neck muscle strength or cervical spine mobility predict later neck disability has not been demonstrated. In this 16-year prospective study, we investigated whether neck muscle strength and cervical spine mobility are associated with future neck pain and related disability in women pain-free at baseline. Methods Maximal isometric neck muscle strength and passive range of motion (PROM) of the cervical spine of 220 women (mean age 40, standard deviation (SD) 12 years) were measured at baseline between 2000 and 2002. We conducted a postal survey 16 years later to determine whether any subjects had experienced neck pain and related disability. Linear regression analysis adjusted for age and body mass index was used to determine to what extent baseline neck strength and PROM values were associated with future neck pain and related disability assessed using the Neck Disability Index (NDI). Results The regression analysis Beta coefficient remained below 0.1 for all the neck strength and PROM values, indicating no association between neck pain and related disability. Of the 149 (68%) responders, mean NDI was lowest (3.3, SD 3.8) in participants who had experienced no neck pain ( n = 50), second lowest (7.7, SD 7.1) in those who had experienced occasional neck pain ( n = 94), and highest (19.6, SD 22.0) in those who had experienced chronic neck pain ( n = 5). Conclusions This 16-year prospective study found no evidence for an association between either neck muscle strength or mobility and the occurrence in later life of neck pain and disability. Therefore, screening healthy subjects for weaker neck muscle strength or poorer cervical spine mobility cannot be recommended for preventive purposes.
... Other studies have examined maximal voluntary contraction of shoulder and neck muscles among females with musculoskeletal disorders compared to healthy females. These studies found females with musculoskeletal disorders (including pain) to have lower maximal voluntary contraction compared to healthy controls [36][37][38][39] . Likewise, several studies have found strength training to decrease pain in lower back, spine, neck, and upper extremities in various populations [12][13][14][15][16][17] , the lack of any association between muscle strength and pain severity in the present study was surprising, but is likely related to the amount of missing data. ...
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Objectives: The risk of musculoskeletal pain increases when there is an imbalance between work demands and physical capacity. Work in elder care requires frequent periods of high mechanical loading. Body weight can further amplify this load, while muscle strength may lessen the relative strain on the musculoskeletal system. The purpose of this study was to assess the correlation between body composition, muscular strength and localized musculoskeletal pain intensity in overweight female health care professionals. Methods: A sample of 139 overweight female health care professionals working in elder care were included in the analyses. Associations between BMI, fat percentage, waist circumference, muscle strength and localized pain intensity were assessed using Kendall’s rank correlation. Results: Significant associations were found between musculoskeletal pain in the right shoulder and BMI (rτ=0.194; p=0.035), whereas upper back pain was associated with fat percentage and waist circumference (rτ=0.212; p=0.023 and rτ=0.212; p=0.024, respectively). Conclusions: Results indicate high BMI, fat percentage, and waist circumference may be contributing factors of localized musculoskeletal pain intensity of the upper body in overweight female health care professionals. These results may help guide the design of future workplace health promotion programmes.
... Las dolencias de tipo musculoesquelético representan uno de los mayores problemas en el ámbito laboral, siendo una de las principales causas de ausencia del trabajo por motivos de salud. Por este motivo, numerosos estudios han analizado los posibles beneficios de la actividad física sobre el dolor lumbar y cervical, entre otros, en diferentes poblaciones de trabajadores; dichos estudios han observado mejoras significativas en la percepción del dolor tras la implementación de diferentes programas de entrenamiento de la fuerza con intensidades de esfuerzo predominantemente altas (37). ...
... Los efectos beneficiosos de la AF sobre la prevención y el tratamiento de la mayoría de las enfermedades crónicas son bien conocidos (29). En general, la exposición a mayores niveles de AF global ha sido asociada a menores niveles de ALE tanto de corta como de baja duración (59,86), y las intervenciones con programas de ejercicio orientados, de manera específica, al tratamiento de determinadas condiciones crónicas, han resultado efectivos (37,69). Se han sugerido asociaciones dosis-respuesta al producirse mayores reducciones de ALE con AF de intensidad vigorosa que con intensidad moderada (63). ...
... In the study by Losina et al., PA is measured by accelerometry (34) , whereas in the rest of the studies, PA is self-reported. The objective measurement of PA through accelerometry, instead of being taken by questionnaires, has been suggested by several authors as a necessity to improve quality research on this field (12,37) . Regarding absenteeism, only two studies include company reports (33,36) and the rest self-report this variable through not validated questionnaires, which points to a possible measurement risk of bias of sickness absenteeism. ...
Thesis
Sickness absence is a multicausal phenomenon influenced by the working environment, job role and lifestyle. Its high cost is supported by companies and public institutions in accordance with the current legislation and represents a substantial part of the budget for many countries. Nevertheless, this is not only an economic issue but also a public health issue; longterm sickness absence has been associated to experience disability pension, as well as mortality risk. Both chronic conditions and diseases have been pointed at among its main relevant causes, occasionally, linked to specific occupational classes. Thus, back pain (i.e. low back pain and neck pain), mental disorders (i.e. anxiety and depression) and different cardiovascular diseases have been observed among the most prevalent in workers experiencing long-term sickness absence. On the other hand, moderate and high levels of physical activity, particularly when they are performed during leisure or when commuting to work, have been associated with lower sickness absence, as well as lower of the most common chronic diseases among both general and specific populations of workers. In addition, this inverse association has been observed to be more pronounced with higher leisure-time physical activity. The aim of these studies was to widen knowledge about the physical activity and sickness absence relationship, focusing on its observation among different samples of Spanish and Danish workers, specific population of workers, as well as chronic conditions and diseases associated with these situations. Observational studies examining samples of both Spanish and Danish workers were carried out. Manuscripts II and III analysed two samples of university workers (n=1025 and n=757). Manuscripts IV and VI followed up a general (n=10427) as well as a specific sample of Danish workers (n=4699). Manuscripts V, VII and VIII investigated samples of general populations of Spanish workers (n=9512 y n=9885). Tools such as International Physical Activity Questionnaire (IPAQ) were used to estimate physical activity levels, while sickness absence was assessed through either a question included in the questionnaires or the Danish Registry for Evaluation of Marginalization (DREAM). Analyses were adjusted for different control variables appointed by literature and collected in the questionnaires. Results of the present Thesis showed an inverse association between physical activity and sickness absence in Spanish workers. Such association was observed stronger with higher levels of physical activity and certain subgroups of workers. Similarly, an inverse association between physical activity and certain conditions (i.e. chronic back pain, depression, anxiety, hypertension, diabetes, work-related stress, and usual activity limitations). Moreover, leisuretime physical activity reduced the risk of long-term sickness among Danish workers. In conclusion, the results suggest that higher levels of physical activity associates with lower prevalence and risk of sickness absence. Strategies based on promoting physical activity during leisure might be beneficial for reducing sickness absence.
... 40 strengthening the spine-stabilizing musculature may thus counteract any disturbances in muscle activation patterns, weakness and fatigability inducing and/ or resulting from the experience of back pain. 12,[41][42][43][44] An unexpected finding was that although exercising at a higher intensity was more effective, higher subjective perceived physical exertion levels during the exercise sessions intensified back pain. This ostensible contradiction might be explained by a combination of physiological and psychological effects. ...
Article
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Background: Exercise is considered an effective intervention to relieve chronic back pain. However, it is still unknown whether specific exercise patterns vary in terms of their efficiency and effectiveness. Aim: To investigate the differential health and economic effects of intensity, specificity and degree of subjective perceived physical exertion across five exercise patterns (endurance, gymnastics, fitness, back gymnastics, multimodal back exercise) in adults with back pain. Design: Longitudinal observational cohort study over a period of 24 months. Setting: Various non-therapeutic exercise facilities (e.g., outdoor, fitness centres, health insurance programmes, sports clubs) across one federal state of Germany (Baden- Wuerttemberg). Population: Adults with back pain (N = 2,542, Mean = 46.9 years, 66% females, Graded Chronic Back pain GCPS 1= 40.5%, GCPS 2= 27.3 %, GCPS 3= 20.7 %, GCPS 4= 11.5 %). Methods: Self-reported back pain (functional restrictions and pain = Back Pain Function Score, BPFS) and characteristics of exercising behaviour (frequency, duration, type, physical exertion) were assessed at baseline and at 6, 12, 18 and 24 months. Direct medical costs for back disorders (International Classification of Diseases, Dorsopathies: M40 - M54) were compiled from health insurance records. Results: Moderate- to high-intensity exercise patterns were effective in reducing back pain, particularly at lower levels of subjective perceived physical exertion. At these intensity levels, multimodal back exercise (i.e., exercising the spine-stabilizing muscles specifically, ergonomic training) was 14.5 times more effective than non-backspecific fitness exercise in reducing back pain (BPFS). The beneficial effects of both exercise types increased with the initial severity of back pain. However, only multimodal back exercise (moderate- to high-intensity/high back specificity) was associated with a significant decrease in direct medical costs for back pain. Conclusions: Targeted exercise of the spine-stabilizing musculature at moderate to high intensities without maximum perceived exertion is effective and efficient in reducing back pain.
... When physical exercise has been directed toward treating specific pain or injuries in the workplace, good results have previously been reported. 13,14 In particular, leisure-time physical activity (LTPA) has been inversely associated with the risk of stroke and all-cause mortality in adults. 3,15 Even some psychosocial hazards, such as perceived stress, depression, and burnout, have been inversely associated with high levels of physical activity. ...
Article
Full-text available
Objectives: This study examined the association of leisure-time physical activity (LTPA) with the risk of long-term sickness absence (LTSA). Methods: A total of 10427 subjects from the general working population in Denmark answered questions about physical activity habits, health and work environment in the 2010 Danish Work Environment Cohort Study (DWECS). Data on LTSA (≥6 consecutive weeks during 2-year follow-up) were obtained from the Danish Register for Evaluation of Marginalization (DREAM). Cox regression analysis censored for competing events and adjusted for potential confounders (age, sex, BMI, smoking habits, depression, cancer, back diseases, previous LTSA, occupational social class, and psychosocial work environment) estimated the association between the predictor (LTPA) and the outcome variable (LTSA). During the 2-year follow-up period, 9.2% of the studied population experienced LTSA. Results: In the general working population, moderate LTPA was not associated with LTSA (HR = 0.89, 95% CI: 0.72 - 1.09), while high LTPA showed a tendency (HR = 0.77, 95% CI: 0.59 - 1.01). In subgroup analyses, women below the age of 45 years with high LTPA showed a significantly lower risk of LTSA when compared with their low LTPA counterparts (HR = 0.44, 95% CI: 0.25 - 0.78). Conclusion: The results suggest that high levels of physical activity during leisure is associated with a lowered risk of LTSA, especially among younger women.
... [1][2][3][4] When specifically aiming to reduce musculoskeletal pain in the neck and shoulder, targeted resistance training has proven effective. [5][6][7][8] To induce physiological changes, exercise intensity is an essential component of resistance training. 9 Performing resistance training to a level of exhaustion, that is, until one is unable to continue performing the exercise with the complete range of movement because of fatigue, is known as training to failure. 10 Exerciseinduced effects of training to failure include an increased activation of the motor units and a greater mechanical stress on the musculature, both of which are related to enhanced gene expression and muscular damage with subsequent muscle repair. ...
Article
Full-text available
Background: Resistance training to failure is an advanced method often used by healthy individuals. Little is known about this type of training in individuals with musculoskeletal pain. Purpose: This study investigates the effect of 10 weeks’ elastic resistance training on neck and shoulder muscle activity during a single set to failure. Study design: This was an observational cohort study. Methods: Sixteen untrained, female office workers with chronic neck and shoulder pain performed 10 weeks of elastic resistance exercise as a single set of lateral raise to failure during workdays. Electromyography (EMG) amplitude and median power frequency (MPF) from the splenius and the upper trapezius muscles were analyzed. Results: EMG amplitude increased and MPF decreased linearly from the first to the last repetition during the set, before and after the 10 weeks of training. For the first few repetitions of exercise, muscle activity was higher after 10 weeks than before the intervention (91% vs.74%, P = 0.03). However, during the last repetitions, similar high levels of EMG amplitude were noted both before and after the 10 weeks (129% vs.127%, P = 0.81). The MPF before and after the training intervention was 79 and 77 Hz (P = 0.69), respectively, during the first repetitions, and 66 and 69 Hz (P = 0.62) during the last repetitions of exercise. The increase in EMG and decrease in MPF –which were similar before and after 10 weeks – are good indicators of acute muscle fatigue. Conclusion: The results indicate that untrained women with neck-shoulder pain are capable of training to failure, and concur with previous results showing rapid benefits in terms of muscle strength and pain reductions from this type of training.
... It can be speculated that those being very tired may use high-intensity physical activity in leisure-time to cope with a stressful job. In fact, high-intensity resistance training has shown beneficial effects on maximal muscle strength and muscular fatigue resistance in female office workers with trapezius myalgia, having lower strength capacity than their healthy colleagues [29]. Resistance training hence preserves beneficial effects on sedentary workers. ...
... time until force decreased below 50% of maximum force) among workers with physically demanding jobs [34]. Ten weeks of strength training also improved muscle peak force during 100 consecutive maximal voluntary contractions of shoulder elevation in women with trapezius myalgia, indicating an improved muscular endurance [29]. Increased muscular strength and improved muscular fatigue resistance elicited from resistance training therefore seems highly relevant for workers with physical jobs to prevent or delay fatigue development during work and thereby sustain higher force production. ...
Article
Full-text available
Aim: In spite of the many health-related benefits of regular physical activity, fatiguing work may be a barrier to performing leisure-time physical activity. This study investigates the association between work-related fatigue and the duration of low- and high-intensity leisure-time physical activity in workers with sedentary and physically demanding jobs. Methods: From the 2010 round of the Danish Work Environment Cohort Study, currently employed wage earners from the general working population ( N=10,427) replied to questions about work-related fatigue (predictor) and duration of low- and high-intensity leisure-time physical activity (outcome). Associations were modelled using general linear models controlling for various confounders. Results: Among workers with physically demanding jobs, higher levels of work-related fatigue were associated with gradually lower levels of leisure-time physical activity - for low, moderate and high levels of work-related fatigue the duration of high-intensity leisure-time physical activity was 133 (95% confidence interval (CI) 127-178), 134 (95% CI 109-160) and 113 (95% CI 86-140) min per week, respectively (trend test p<0.001). The duration of high-intensity leisure-time physical activity was lower among older workers (≥50 years) compared to younger workers (<50 years) (132 ± 126 vs 168 ± 150 min per week) ( p<0.0001). Conclusions: The duration of high-intensity leisure-time physical activity gradually decreases with increased work-related fatigue in workers with physically demanding jobs. Older workers perform less high-intensity physical activity than younger workers. Workplaces should consider initiatives to allow workers with physically demanding jobs and older workers to perform physical exercise during working hours and thereby increase physical capacity to meet the job demands.
... Other studies have investigated the ability to perform an isometric maximal voluntary contraction (MVC) of the shoulder elevation muscles among female workers with self-reported neck/shoulder pain. The findings showed that females with neck/ shoulder disorders generated a significantly lower force during maximal shoulder elevation compared to healthy controls (Schulte et al., 2006;Sjogaard et al., 2006Sjogaard et al., , 2010Nielsen et al., 2010;Andersen et al., 2014). Different factors could, theoretically, account for the reduced ability to generate force among subjects with neck/shoulder-disorders. ...
... The difference in MVC between cases and controls in the present study was of the same order as earlier reported (15-20%) Andersen et al., 2014). In spite of the small sample and the large inter-subject variability partly due to the mix of male and female subjects (Fig. 4a), a significant difference between cases and controls was revealed in the gender normalized data. ...
Article
Subjects reporting neck/shoulder pain have been shown to generate less force during maximal voluntary isometric contractions (MVC) of the shoulder muscles compared to healthy controls. This has been suggested to be caused by a pain-related decrease in voluntary activation (VA) rather than lack of muscle mass. The aim of the present study was to investigate VA of the trapezius muscle during MVCs in subjects with and without neck/shoulder pain by use of the twitch interpolation technique. Ten cases suffering from pain and ten age and gender matched, healthy controls were included in the study. Upper trapezius muscle thickness was measured using ultrasonography and pain intensity was measured on a 100mm visual analog scale (VAS). VA was calculated from five maximal muscle activation attempts. Superimposed stimuli were delivered to the accessory nerve at peak force and during a 2% MVC following the maximal contraction. Presented as mean±SD for cases and controls, respectively: VAS; 16.0±14.4mm and 2.1±4.1mm (P=0.004), MVC; 545±161N and 664±195N (P=0.016), upper trapezius muscle thickness; 10.9±1.9mm and 10.4±1.5mm (P=0.20), VA; 93.6±14.2% and 96.3±6.0% (P=0.29). In spite of significantly eight-fold higher pain intensity and ∼20% lower MVC for cases compared to controls, no difference was found in VA. Possible explanations for the reduction in MVC could be differences in co-activation of antagonists and synergists as well as muscle quality.