Effectiveness of Physical Training Interventions for Work Related Upper Extremity Disorders (Wrued) from A Sports Science Perspective. A Systematic Review!

Work-related upper extremity disorders in the workplace have emerged as a major influencing factor in the working environment [1]. On the one hand, they are risk factors for the employee, who is confronted with possible damage and symptoms of the disease. On the other hand, sick workers are a cost factor for the company and the health care system. Absenteeism, therapy and treatments generate costs. A disease or injury cause both direct and indirect costs to society [2]. Direct costs are the costs that are required to treat diseases. These include the medical costs associated with a disease, including labour costs for medical professionals. Indirect costs of diseases or injuries include loss in potential work performance at the workplace [3]. Today the computer workplace is considered to result in negative health effects for employees due to the long hours of one-sided, static work postures and high repetition. Both muscles and passive structures are affected by pathological changes or diseases due to computer work. Repetition, static working posture and mechanical stress have been found to be the main physical causes of work-related upper limb disorders in computer workers [4]. Continuous stress, rapid movements, restricted posture can be other causes. Examples of repetitive strain injuries include tendonitis, neuritis, fasciitis, myositis, cubital tunnel syndrome, thoracic outlet syndrome, carpal tunnel syndrome, degenerative arthritis, tendinosis, fibromyalgia, disc herniation, focal hand dystonia and neuropathic pain [5].

The European Agency for Safety and Health at Work (EUOSHA), reported in 2017 that 3.9% of global gross domestic product (GDP) and 3.3% of European GDP is spent on managing work-related injuries and diseases [6]. Training interventions have been shown to be effective against upper limb disorders at the computer workplace in numerous studies with remarkably good pain-reducing effects of strength training. Some studies reported the positive results of strength training, especially for office workers with upper limb symptoms [7-9]. In addition significant results have been achieved in endurance training to reduce symptoms in the shoulder and neck area [10], as well as pain-reducing effects by stretching interventions [11,12].

Therefore this review focuses on the most appropriate specific physical training interventions and exercises to reduce upper limb pain and disorders in contrast to earlier reviews. Reviews have already been made regarding exercise interventions. Although some reviews with mixed interventions for upper limb disorders have been publishedn [13,14] and also discuss training interventions for office workers [15] and for office workers with neck pain at baseline of training interventions [16], a systematic review on computer workplace training interventions for the upper extremity with specific symptoms and disorders of the wrist, elbow, shoulder, cervical and thoracic spine and the neck is missing. In addition, it was intended to pay specific attention on training interventions in the areas of strength, endurance, coordination and flexibility to discuss the effectiveness of training interventions and exercises from a sports scientific perspective.

Objectives study selection

This review focuses on the effectiveness of training interventions for computer workers. The following questions are relevant: Which training interventions reduce upper limb symptoms and disorders? Which training interventions achieve muscular improvements?

Eligibility criteria

Randomised controlled trials (RCT) were included. The criterion was that at least one group included an intervention with physical activity or physical training. The training interventions were to be performed at the workplace or presented at the workplace. Controlled trials (CT) were also added if they involved physical interventions during the working day as well. Studies published in English or in German were included. Symptoms or diseases of the upper extremities had to be present at the beginning of the intervention.

Symptoms and diseases of the neck (including resulting headaches), cervical spine, thoracic spine, shoulder, elbow, and wrist were included. Studies were selected that included female and male office workers. The office workers were required to be primarily computer workers during their occupational activities. Studies with ergonomic, preventive, written only exercise advice (brochures) or psychological interventions were excluded. The search for publications has been limited to the period from: 01.01.2000 – 31.12.2020. This review protocol follows the reporting guidelines for systematic (Prisma).17 Results are presented in accordance with PRISMA guidelines.

Data search and literature searches

The databases Medline, MEDLINE (via Ovid) were used for the literature search. Studies from 01.01.2000 – 31.12.2020 are considered. The literature search was checked by the authors. Examples of search terms are given below (work related upper extremity disorders AND workplace interventions AND office workers). The following criteria were used: the subjects studied were computer workers and had symptoms or upper extremity disorders at baseline. The following structures were included. Pain or disease of the upper extremity (neck including resulting headaches, cervical spine, thoracic spine, shoulder, elbow and wrist).

Data sources and searches

Data were extracted using predefined data fields. The predefined data fields were adapted based on the PICO (Population, Intervention, Control and Outcomes) process.

In this review, the following data fields were selected:
I. Population: office workers, computer workstation
II. Intervention: physical activity and training programme
III. Control: comparison intervention
IV. Outcome: main criterion of the training programme of the training group
V. Results: What were the results of the study

Data extraction and quality assessment

The predefined data fields were adjusted based on the PICO (Population, Intervention, Control and Outcomes) process. The data were categorised into subgroups based on the type of intervention (e.g. strength, endurance).

Overview interventions

Table 1:Training interventions.

Duration of the intervention

Of course, implementability plays a major role in the effectiveness of workplace training programmes. Several authors [7,9,18-22] in this review have shown that short sessions lead to a significant reduction in neck and shoulder pain. Studies of 2 to 15 minutes have shown a reduction in pain. Training interventions of short duration can be easily included in the daily work routine. Some authors [7,20,21] presented a training intervention of 2 or 12 minutes. Andersen C.H. et al. [18], presented different durations in their study, the shortest training intervention time in their study lasts 7 minutes. In the same study another training format lasted 60 min.

All training groups in this study [18] 1x60 min, 3x20 min. and 9x7 achieved a significant pain reduction (p<0,01). Theoretically, short intense training sessions repeated through a day, may improve the restitution, reduce muscle tension, increase temperature and blood flow in the painful muscles when compared to longer sessions. The use of such pain-reducing sessions should ideally be done without or with simple equipment, like tubes, small dumbbells or even without equipment. All authors in the review used elastic tubes, dumbbells or used no additional equipment.

Frequency

Andersen C.H. et al. [18] showed in their study on frequency and duration of strength training that one hour (1 x 60 minutes), 3 x 20 minutes and 9 x 7 minutes per week achieved a reduction in pain. Of course, studies with a short duration of the training intervention had a higher frequency per week [7]. In summary, for interventions of less than 15 minutes, scientists opted for a minimum frequency of five times every working day [7,9,20,21,23]. As soon as the duration was over 20 minutes, two to three times per week were sufficient [25-27]. One example is the study by Blangsted et al. [26], which also achieved a statistically significant reduction in pain with a training intervention of three times a week. As different frequencies achieved significant pain-reducing effects, an employer can choose between different times and associated frequencies of training interventions. Experience shows that employees can cope better with short daily sessions than with longer sessions three times a week. The issue of non-motivation arises less when the intervention is daily and shorter.

Intensity

The American College of Sports Medicine (ACSM) minimum exercise guidelines recommend 1 set (8–12 repetitions) of 8 to 10 resistance exercises to train the major muscle groups 2 days per week.28 Progressive strength training has been proven to reduce pain. Some interventions included resistance progression in intensity. Due to the results of Andersen L.L. et al. [27] almost all interventions since than had a moderate start and increased in repetition maximum and resistance over the duration of the intervention. Andersen L.L. et al. [29] identified a risk factor in rapidimpact strength training in people with neck pain. Feedforward mechanisms like fear of increased pain reduces rate of descending drive of both painful and pain free synergistic muscles during the phase of rapid rise in muscle force. Neural inhibitory feedback mechanisms limit maximal activation of painful muscles during the stable high-force phase of maximum voluntary contraction. Andersen L.L. et al. [29] suggests that a feedback mechanism is responsible for the impairment of painful muscles during maximal force development coming from muscle spindles and Golgi tendon organ. Jay et al. [24] mentioned a pain reducing mechanism in a study investigating the effects of explosive resistance training on non-chronic muscle pain. The desensitization of chemo nociceptive nerve endings by local functional hyperaemia mechanisms normalizing intramuscular metabolite concentrations. Flushing of metabolite build-up might also play a role locally in the muscles when looking for possible explanations to reductions in pain following light and frequent resistance training.

The fear of performing rapid movements in conditions of chronic pain, designates that during the initial phase of rehabilitation, exercises should be performed in a controlled manner to ensure a high level of muscle activation in both painful and pain free muscles. During later phases of rehabilitation, more powerful execution of exercises may be employed [29].

Measuring method

Eight studies included elastic tubing for strength interventions (Table 2). Measurements of maximum strength were checked in several studies with handheld isometric strength testing device [30-33]. An examiner determined muscle strength as the maximal torque value [7,20]. Saeterbakken et al. [10] performed with the participants isometric shoulder elevation (shrugs). The participants were holding a barbell standing in an upright position vertical above a force cell attached to the floor. The participants performed three tests with 1-2 minutes pause between each attempt. The greatest mean force output over a three seconds window from a five seconds maximal voluntary contraction was used in the analyses. Each exercise was conducted with two sets.

Table 2:Training intensity strength training.

Strength exercises

Most of the authors reported in this review have shown an activation of the shoulder girdle [7,9,18,20,21,25-27]. Interventions applying intensive muscle training have used exercises which besides the targeted painful muscles have shown to activate the majority of muscles in the shoulder girdle. Another influencing factor for both neck and shoulder pain seem to be the position of the scapula and the humeral head. Significant results in pain reduction could be achieved in studies with direct involvement of the shoulder muscles. Three studies used in their exercise program only one exercise lateral raise [7, 20,21].

Very remarkable is the result of Andersen C.H. et al. [19] with a training approach involving the scapula fixators without direct training stimulus, training exercise for the neck muscles.

Therefore, an abnormal location of the scapula caused by abnormal muscle action around the shoulder joint can lead to limitation of scapulothoracic joint movement. Eventually, this causes stress to the joint capsule of the scapulohumeral joint causing impingement syndrome and instability in the shoulder girdle [34]. Ludewig & Cook [36] found in their study of subjects with impingement symptoms that reduced serratus anterior function in subjects with shoulder impingement was consistent with reduced posterior tipping. Symptom-enhancing changes in the scapula are thought to be a decrease in the serratus anterior muscle and an increase in the muscular activity of the upper part of the trapezius muscle. Another reason is a dysbalance between the upper and lower parts of the trapezius muscle. Stability and muscle strengthening are more important because the shoulder is very mobile. Among the muscles that act to maintain shoulder stability, the serratus anterior is important for maintaining scapulohumeral rhythm [37]. When elevating the upper limb, it helps upward rotation and posterior tilt /retroversion of the scapula and holds the scapula to the thoracic cage to prevent winging scapula [38].

Table 3:Exercise Intervention: an overview of exercises that occur in the studies with significant results.

The four most common exercises used in the training interventions were Lateral Raise, Reverse Fly, Rowing and Shrugs (Table 4), these are exercises that train the posterior shoulder girdle muscles. They are exercises that directly target the affected structures. In the interventions, no rotational exercises were used in the shoulder girdle. They could place the humeral head centrally in the shoulder girdle. The study by Blangsted et al. [26] showed an abduction with supraspinatus attention in the programme. This study showed statistical significance in pain intensity and duration (Table 5: p=0.0318 pain intensity and p=0.0565 pain duration). The studies that included shoulder girdle exercises achieved a statistical reduction in pain (Table 5). Many events in daily life are characterised by a limited time for developing strength in postural coordination and control strategies [20]. Therefore Jay et al. [20] investigated peak torque (PT) and rate of torque development (RTD). The highest obtained values for PT and RTD were selected for statistical analysis.

The increase was significantly different compared to controls (p<0.05, Table 5) for both training groups. Epidemiological studies are often based on questionnaires or software-based registrations of computer use but lack physiological measurements, for example, muscle activity patterns. Tension or activity of the neck/shoulder muscles may play an important role in the development of neck/ shoulder pain and can be measured with electromyography during work [21]. Specifically, Lidegaard et al. [21] hypothesised that the training group would have an increased frequency of EMG gaps, a prolonged duration of EMG gaps and a greater proportion of time with minimal muscle activity compared to the control group. Compared with control, training increased isometric muscle strength 6% (p<0.05) and decreased neck/shoulder pain intensity by 40% (p<0.01, Table 5). Sjögren et al. [34] examined the effectiveness of light resistance training with guidance. They choose different exercises in their study. Exercises for upper extremity flexion, extension, trunk and legs. Light resistance training and guidance can decrease headache and neck symptoms among symptomatic office workers (p=0.001, Table 5). Apart from Andersen C.H. et al. [18], another four 30,31,32,33 studies completed an exercise for the serratus anterior (pullovers).

All studies that included the serratus anterior also had statistical results regarding pain reduction (Table 5). The pullover exercise is also a pectoral muscle exercise. Exercises for the pectoral muscles are therefore only found in the form of pullovers in the same four studies. However, the pectoral muscles create a balance to the already tense back musculature and would also lead to structural relief for the participants directly in the programme. In the longer term, a balanced programme in the shoulder girdle is essential. Viljanen et al.35 had no significant effects on pain intensity. The intervention consisted of light strength training and relaxation training techniques.

Table 4:Significant results on main outcome.

Aerobic exercise

Saeterbakken et al.10 presented a study with two different training interventions. One group performed a strength training and the other group performed Nordic walking. The differing patterns could be caused by the nature of the activities. Nordic walking is not very fatiguing for the neck and shoulder muscles, whereas specific strength training is. Initially Nordic walking could be a softer option for these muscle groups.

Both training groups demonstrated a similar, but significant reduction in pain intensity (P=0.014-0.018). Nordic walking could be a gentler start for painful upper extremity disorders. Therefore, aerobic exercise may modulate central sensitization mechanisms, increase pain thresholds, and reduce the formation of Myofascial Trigger Points. Aerobic exercise provides a potential non-invasive and cost effective alternative or complementary treatment to current management strategies.39

Aerobic exercise has been shown to increase circulating concentrations of the angiogenic cytokines PlGF, bFGF and sFlt-1, as well as IL-6 and IL-8 in both endurance trained and sedentary young men.40 The exercise-training status significantly affect the circulating cytokine response to 30 minutes of acute exercise at the same relative exercise intensity. Regular endurance exercise training is associated with lower levels of inflammatory markers in the basal state compared to pre-training levels.41 Endurance training such as Nordic walking relieves tension and reduces the risk of inflammation in the body. It is likely that the use of aerobic exercise at lower levels of perceived tension would be a helpful approach to minimise the risk of a continuing chronic pain condition. Movement restrictions of ROM cannot be satisfactorily improved with Nordic Walking. Therefore, endurance training combined with specific exercises for the upper extremities should be offered. The technique and use of this form of exercise is easy to train and perform. Due to the longer duration, it is probably too time-consuming during working hours.

Stretching interventions

Tunwattanapong et al.22 reported in their stretching intervention a duration of 15 minutes. Stretching exercises of the neck and shoulder area can reduce pain, and improve neck function and quality of life of office workers. In this study22 significant results were found with respect to VAS pain scores from baseline 6.6 (1.2) to post intervention 4.8 (1.8) within the intervention group compared with the control group (6.2 [1.0] to 5.6 [1.8], postintervention p=0.001).

Several laboratory researches have demonstrated that stretching leads to elongation of the muscle tendons unit, reductions in maximum force, rate of pressure production, and tensile tension on the muscle tendon device. Therefore, stretching seems to alter the viscoelasticity of the muscle tendon unit, leading to less stiff tissues. These types of changes increase the distance the tissue can stretch and also the force required to tear the muscle tendon unit, producing injury less likely. The supposition is that, for individuals with brief or “tight” muscles, stretching out increases flexibility by lengthening the tissues to a more physiologically normal range, promoting ideal function and reducing the chance of musculoskeletal injury.42 According to Hess and Hecker,43 recommend the following criteria for an effective stretching program:
a) Warm-up for five minutes prior to stretching.
b) Exercises should be tailored to commonly performed job duties.
c) Stretch regularly: a minimum of two–three days/week.
d) Perform stretches correctly.
e) Hold stretch 15–30 seconds.
f) Two-three repetitions per muscle group

Tunwattanapong et al. [22][ reported that a stretching program 10 – 15 Minutes, twice a day, 5 times a week, can reduce pain. Perhaps the stretching approach is effective for office workers who have a very high level of perceived pain and can therefore imagine themselves in a slower, more deliberate approach to movement. It may be that people inexperienced in movement start with static stretching to first become aware of the affected muscles. Subsequently, other interventions may make additional sense.

Combined Interventions Cardio Training and Strength Training

Pain education combined with specific training and aerobic exercise reduce neck pain more than pain education alone in women with chronic neck pain [44]. Sjøgaard et al. [45] described in their study benefits of a combined training intervention. Intelligent physical exercise training at work as IPET benefits the worker in terms of decreasing health risk indicators, improving physical capacity and functions as well as perceived health. The employer also benefits in several ways from combined training, as absenteeism due to sickness is reduced and productivity increases. Sjøgaard et al. [45] mentioned that on the societal level exercise can be “more than medicine” since exercise in a specific manner can maintain the individual’s ordinary daily physical functions and ability to move (walk and run).

Blangsted et al. [26] reported statistically significant differences between those who performed “physical activity” and the reference group, both with regard to improvements in the intensity and the duration of symptoms according to tests of one-sided hypotheses. In their study, Blangsted et al. [26] could not find a significant difference between the strength group and the “all around fitness exercise group” in terms of pain intensity and duration of pain. There were no statistically significant differences between the outcomes in the two “physical-activity” groups for pain intensity (p=0.5327) and pain duration (p=0.4016). The Results in Andersen et al. [27], showed that during the 10-week postintervention follow up period, no change in pain occurred in any of the 3 groups, and the SST (Strength) group remained at a level that was significantly lower than the GFT (General Fitness) and the reference group. The results of the combined interventions show no significant reduction in pain intensity in some studies. They do not only target the affected muscles. Of course, combined interventions have a general health effect. Health risk indicators are reduced and physical capacity is increased.

Posture exercises

Mongini et al. [46] and Rota et al. [47] included neck, shoulder and relaxation exercises in their study. The advantage of this intervention was the simple composition of the programme, which could be completed both at work and at home. The postural exercises focused on mobility of the thorax and neck. A restricted ROM can be influenced by a postural misalignment and muscle imbalance. The literature suggests that there is evidence that exercise may improve posture in the upper thoracic area, helping improve mobilization of the shoulder muscles, and consequently leading to an increase in ROM [46]. Mongini et al. [46] found a higher responder rate for neck/shoulder pain (95% CI 1.53; 1.27 to 1.82) and a larger reduction of the days per month (95% CI) with neck / shoulder pain (2.51; 3.56 to 1.47). Rota et al. [47] found statistically significant results -0.19 (95% CI: -0.3 to - 0.07) for Pericranial Muscle Tenderness, -0.20 (95% CI: -0.31 to -0.08) for Cervical Muscle Tenderness, -0.36 (95% CI: -0.57 to -0.16) for Cumulative Muscle Tenderness.

Studies with Qui gong [28] and manual therapy [48] were also included in the training interventions. Both studies had significant results. The manual therapy study found a significant increase in PPT. The PPT on the left side was 3.07 kg/cm2 before training and 6.20 kg/cm2 after training, indicating a statistically significant increase of 3.69 kg/cm2 (p<0.001). Qui gong showed a small significant reduction in disability neck (Disability neck von Korff, 0.29, 0.52 to 0.07, Confidence Interval 95 %, 0.52 to 0.07). Simple exercises without resistance are probably the easiest way to become aware of one-sided postures. Through mobility exercises, very high levels of pain and limited range of motion can be experienced without the stress of resistance.

Many interventions, especially strength and combined interventions, proved to be successful. They achieved significant results compared to the control groups. When used in the workplace, it makes sense to choose short and effective strength interventions. The most frequently mentioned exercises were lateral raise, shoulder abduction, reverse flies and shrugs. It probably makes sense to start a gentler exercise path with lower intensities in the strength area or in the mobility and stretching area [22,46,47,10] at the beginning of the intervention, especially in high pain states, in order to improve feedforward mechanisms mentioned by Andersen et al. [27] With lower pain levels at baseline, it is important to use the strength interventions to change the muscle fibres in a sustainable way and to better tolerate future occupational loads.

Apart from strength training, there was also a significant reduction in pain during endurance training (Nordic walking). Nordic walking circulates the entire body through the endurance approach and reduces inflammation in the body. A combination with strength and mobilisation exercises makes sense, as complaints often go hand in hand with ROM restrictions and Nordic walking does not increase ROM in the affected joints of the upper extremity. Exercise variations that specifically relax the neck and shoulder muscles also produced significant results.

Exercises help employees become aware of tension in the affected areas and learn to reduce tension through mobilisation and stretching exercises during working hours. In the meantime, there is a wide range of training methods that can be used in everyday work to reduce pain.

Table 5:Recommended training exercises from the reviewed literature.

i. Many interventions, especially strength and combined interventions, proved to be successful
ii. At the workplace, it makes sense to choose short and effective strength interventions.
iii. The most frequently mentioned exercises were lateral raise, shoulder abduction, reverse flies and shrugs
iv. In high pain states it makes sense to start a gentler exercise path with lower intensities in the strength area or in the mobility and stretching area

Appendix 1:Literature Search Strategy used in this review.

None.

No conflict of interest.

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