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The aim of this investigation was to study the influence of age on energetic requirement, muscle fatigue and musculoskeletal risk of prolonged standing work. The study group was focused on female Malaysian operators (typically in electronic industries) who represented one of the largest work populations in the country. Four younger female operators...
Context in source publication
Context 1
... the workload increases, more oxygen intake is required for the body muscles to perform external work and thus, less residual oxygen level in exhaled air. Therefore residual oxygen level in exhaled air can be taken as an indicator of the energy cost of work. Lower oxygen level indicates higher workload and energy expenditure. In this study, a Vernier Oxygen Gas Sensor was used to measure residual oxygen level in human exhaled air. Resting residual O 2 level was measured before the onset of work with the subject seated and at rest. Working residual O 2 level for the two main work tasks were collected at the beginning, middle and end of shift. Gastrocnemius muscle of the leg was selected for EMG testing to study leg fatigue due to prolonged standing. This muscle was chosen instead of the commonly studied low back muscle in order to avoid any religious issues as most of the subjects were Muslims. A posterior view of the gastrocnemius muscle is shown in Figure 1. The ME3000 Muscle Tester was used for EMG measurement. The tester is a portable, small (16 x 7.5 x 2.5 cm) microcomputer, which function as a collection and recording unit with independent storage capability. Metered data was registered using state-of-the-art amplification technology, in which the amplifiers were connected directly to the earthling electrode. This can effectively eliminates disturbance, such as those caused by movements. The EMG readings were interpreted in terms of mean power frequency (MPF) and amplitude. The type of surface electrode used was 3M Red Dot monitoring electrode with circular silver-silver chloride disk, micro pore tape and solid gel. The electrode was disposed once used. The electrodes were placed on the medial head of the gastrocnemius muscle. Figure 2 depicts the fixing places of the electrodes adopted in this research. To measure the MVC of the gastrocnemius muscle of the leg being tested, the subject was asked to make the leg as a weight-bearing leg and then to rise on the toes of the weight-bearing leg through the full available range of ankle plantar flexion, keeping the knee extended. Figure 3 clearly illustrates the condition. Each EMG data entry was collected for 1 min with saving frequency at 1 second intervals. Data was collected when subjects carried out the two main work tasks: (1) Standing, and (2) Material loading/unloading, at the beginning, middle, and end of shift. The EMG amplitude was normalized to the EMG amplitude at 100% maximal voluntary contraction of the gastrocnemius muscle (%MVC). The signals were analyzed for amplitude in %MVC and mean power frequency (MPF). The PLIBEL checklist (Kemmlert, 1995) was used as a practical assessment tool for the evaluation of ergonomic conditions in the workplace. The checklist links questions concerning awkward work postures, work movements, design of tools and the workplace to specific body regions. Furthermore, any stressful environmental or organizational conditions were noted. Statistical analysis was used to test the significance of difference in energetic requirement, muscle fatigue, and musculoskeletal disorders, between the younger subjects (<40yr) and the older ones (>40yr). Out of the eight subjects, all of them complained that they experienced pain and discomfort for the past 12 months in various parts of their body. All of them claimed that the pain and discomfort is caused by their work. Figure 4 depicts the percentage of subjects experiencing pain and discomfort in different body parts. Data was then analyzed separately for the older subjects and the younger ones. It was found that older subjects experience more pain than the younger ones. Figure 5 displays the finding. Comparison was made between these two age groups and statistical t-tests ware done to check for significance of difference. Interestingly, the t-test (two-sample unequal variance, one tail) showed a significant difference between these two age groups ( p = 0.031 < 0.05). In other words, it is statistically proven that younger subjects suffer significantly less pain than the older ones. For those body parts which the subjects had been experiencing pain for the past 12 months, the following questions were ...
Citations
... Further, the results revealed significantly greater co-contraction of ankle muscles of both paretic and non-paretic sides in the HA-stroke group as opposed to the LA-stroke group during standing on the foam surface, suggesting that stroke survivors who had a high level of anxiety may use improper increased cautious/conscious postural control processes while standing on unstable support surfaces. The resultant musculoskeletal stiffening may constrain the flexibility of postural adjustments, disturb appropriate responses to unexpected perturbations, and cause higher electrophysiological costs for postural control [48], possibly resulting in faster muscle fatigue and enhanced risk of fall in such situations [58]. Therefore, further attention should be paid to balance rehabilitation in HA-stroke survivors, not only to prevent falls but also to decrease fatigue and physical strain. ...
Background:
Despite the high prevalence of anxiety among chronic stroke survivors and evidence of its negative effects on postural control in healthy subjects, it is unclear whether anxiety also affects postural control in these patients. Recent evidence of improved postural control of healthy subjects by distracting the attention using an external focus (EF) or cognitive task, raises the question of whether similar benefits would be observed in stroke survivors. Thus, the current study aimed to investigate the effects of anxiety and distracting the attention on postural control of chronic stroke survivors in terms of both postural sway measures and neuromuscular regulation.
Methods:
Postural sway measures and ankle muscle activity of chronic stroke survivors with the high and low level of anxiety (HA-stroke (n = 17), and LA-stroke (n = 17), respectively) and age-, sex-, height-, and weight-matched healthy subjects (n = 17) were assessed while standing on rigid and foam surfaces under following conditions: baseline, internal focus (IF), EF, simple and hard cognitive tasks (SC and HC, respectively).
Results:
Stroke survivors, particularly HA-stroke participants, showed greater postural sway measures (i.e. postural instability) and enhanced co-contraction of ankle muscles (i.e. stiffening of the neuromuscular system) compared with healthy subjects. As opposed to baseline and IF conditions, postural instability and neuromuscular stiffening significantly reduced in EF condition and decreased more in cognitive task conditions, particularly HC condition.
Conclusions:
The results suggest that anxiety enhances stroke-induced postural instability promoting improper neuromuscular control of posture with stiffening strategy, which can be alleviated by EF and cognitive tasks.
... [25] When acquiring the MVIC for the GL, the participants were asked to stand on their right leg, using a chair in front of them for support, and subsequently perform a maximum effort plantar flexion. [26] Due to equipment inaccessibility, the MVIC for the VL was performed with a modified version of a technique which has been previously substantiated greatly. This entailed the volunteers sitting on a sturdy chair, with their hip flexed to 90° and their knee flexed to approximately 60°. ...
Context:
With a long duration return mission to Mars on the horizon, we must learn as much about the environment and its influence on the musculoskeletal system as possible to develop countermeasures and mitigate deleterious health effects and maladaptation.
Aims:
To determine the influence of simulated Mars gravity on the activity of four locomotor muscles while walking, in comparison to 1 G, using lower body positive pressure (LBPP).
Material and methods:
A total of 14 male subjects (mean age: 20.6 ± 2.4 years) performed bouts of walking in both simulated Mars gravity (0.38 G) and Earth gravity (1 G) using an LBPP device. The dependent variables were the muscle activity evoked in the tibialis anterior, vastus lateralis, gluteus maximus and lateral portion of the gastrocnemius, measured using electromyography and expressed as percentages of maximum voluntary isometric contractions, and heart rate (HR). For statistical analysis, a paired t-test was performed. Statistical significance was defined as P < 0.05.
Results:
No significant differences in muscle activity were found across conditions for any of the investigated muscles. A significant mean difference in the HR was identified between Earth (105.15 ± 8.1 bpm) and Mars (98.15 ± 10.44 bpm) conditions (P = 0.027), wherein the HR was lower during the Mars trial.
Conclusions:
The Mars environment may not result in any deteriorative implications for the musculoskeletal system. However, if future research should report that stride frequency and thus activation frequency is decreased in the simulated Mars gravity, negative implications may be posed for muscle retention and reconditioning efforts on the Red Planet.
... These prevalence rates are higher for workers engaged in physically demanding jobs [3,4,6]. One suggested risk factor is prolonged static standing that may induce muscle discomfort, fatigue, lowered blood flow, and increased venous pooling [8][9][10]. Accordingly, a cross-sectional [6] and a prospective study [11] have observed positive associations between self-reported standing at work and pain in the lower extremities, but other studies have not supported this finding [3,4]. ...
... The time pattern of static standing -the time spent in specific uninterrupted bouts of static standing -can be of importance for pain in the lower extremities [15]. It is plausible that long static standing bouts can be a particular risk for pain in the lower extremities [8][9][10]. In contrary, short standing bouts are usually associated with alternation between postures during the workday [17], which can lower the sustained static load of the muscles, provide more variation in lower extremity muscle activation and consequently less local fatigue and venous pooling of blood in the legs. ...
Background: Pain in the lower extremities is common among blue-collar workers, with prolonged static standing as a potential risk factor. However, little is known about the association between diurnal accelerometer measures of static standing and pain in the lower extremities, and the potential importance of temporal patterns of static standing for this association. Research question: We aimed to investigate the cross-sectional association between accelerometer measures of total static standing time and temporal patterns (bout duration) of static standing (short: 0–5 min; moderate: >5-10 min; and long bouts: >10 min) during total day, work and leisure and pain intensity (on a 0–10 scale) in hips, knees and feet/ankles. Methods: Accelerometers were used to measure static standing during four consecutive days among 677 blue-collar workers. Linear regression analyses were used to investigate the association between static standing time and pain intensity in the lower extremities. Results: Total static standing time comprised, on average, 3.9 h per day. 72.6% of the workers were exposed to long bouts of static standing, averaging 0.1 h per day. Short bouts of static standing were positively associated with hip and knee pain during total day, and positively associated with knee pain during work. Also, total static standing time during leisure was positively associated with knee and hip pain. A negative, but not significant, association was found for static standing in moderate bouts at work and hip pain. Significance: Even though the associations found were weak, these findings suggest that the temporal pattern of static standing is of importance for pain in the lower extremities. Future research should examine the possibility that moderate bouts of standing could play a role in preventing lower extremity pain.
... Through this 12 hours working, the operators spent about 88% of standing during performed the task requirement. The long-standing period has far exceeded the threshold limit of the standing time 5) . This continuous exposure can cause muscle fatigue at the body part. ...
Prolonged standing can cause discomfort on the body of the workers and can lead to injury and occupational disease. One of the ergonomic intervention is through improving the work-rest scheduling. The purpose of this study are to identify the fatigue level from the perception of the worker and to investigate the impact of the work-rest scheduling to the standing workers for 12 hours working time with a different gender. This study involved two methods which are self-assessment of the worker and direct measurement by using electromyography (EMG). For self-assessment, 80 workers have been interviewed using questionnaire in order to identify the fatigue level. For direct measurement, EMG was attached to the 15 selected workers at their respective leg and lower back to analyse the muscle efforts. In terms of perception, the results show the discomfort and fatigue level at the lower body region in the following order as foot ankle, lower back and leg. There is a significant difference between gender on discomfort pain for foot ankle and leg. The results show short frequent break by 10 minutes can reduce the fatigue at the leg and infrequent long break is preferable in order to reduce the fatigue at the lower back. In conclusion, it was found that prolonged standing affect the muscle fatigue and discomfort especially lower extremities such as foot ankle, lower back and leg. Besides that, different type of work rest scheduling and gender have significant result towards the muscle fatigue development.
... Standing related occupational injuries come at a cost to both the individuals and the organisations, attributed to decrements in performance and productivity, absenteeism, medical costs and worker health and well-being (Ahmad et al., 2006). It is therefore important to seek clarification about the benefits of currently utilised interventions in order to target risk control strategies that maximise worker health and well-being and consequently profitability to organisations. ...
This systematic review updates the current state of evidence on the effectiveness of softer flooring and cushioned shoe insoles on reducing musculoskeletal discomfort amongst workers who are required to stand for prolonged periods to work and the impact of factors such as age and gender on the outcomes. A systematic search identified 10 unique studies that met the eligibility criteria. The heterogeneity of study designs impacted on the strength of evidence. A moderate level of evidence was found in support of using cushioned materials in reducing discomfort/fatigue among standing workers. A limited level of evidence exists in favour of using insoles over anti-fatigue mats. Insufficient information exists for the impact of gender or age. Larger, good quality prospective intervention trials based in real workplaces that consider the impact of psychosocial and organisational factors on musculoskeletal discomfort whilst standing at work are required to inform industry recommendations.
... Cumulative Trauma Disorders (CTD) is used to describe repetitive strain injuries of musculoskeletal and nervous system (Ahmad, 2006). Generally, sedentary working people such as office workers whose job are mainly focused on computers and typing activity are highly exposed to the risk of CTDs such as carpal tunnel syndrome, tendonitis and low back disorders. ...
Upper Extremity musculoskeletal disorder (MSD) has become a common problem among office workers in Malaysia. Studies have shown that an appropriate work-rest schedule can reduce fatigue and MSDs among office workers. In Malaysia, there has been an increase in the occurrence of MSDs, especially in work that require intensive computer use. Operators who used computers continuously for more than 4 hours a day have shown to develop CTDs. Studies on the effect of break time on the performance of office workers in Malaysia are still lacking. As such this study was aimed to evaluate effect of work rest schedule on the discomfort, performance and muscular load levels of computer users in Malaysia. The effect of break time starting with no break, one minute and 30 seconds break interval were carried out on the 15 subjects. EMG was measured for each task given. Performance which was calculated by multiplying speed and accuracy (WPM) showed 30 seconds break was 13.5% higher than 1 minute break and 20.14% higher than schedule with no break. EMG analyses showed 30 seconds have lowest mean AEMG which was 0.035 for flexor carpi ulnaris and 0.0331 for radialis muscles. It also recorded least discomfort scale for upper extremity muscles compared to the other two schedules. This study showed that more frequent microbreaks can improve performance of office workers and reduce MSD problem from occurring.
... This may affect to discomfort, distraction and possibly reduced job satisfaction and performance. The study conducted by Ahmada et al. (2006), was found that operators spent 87% of their work day in standing task 3. At such long standing hour, it had far exceeded the threshold value of standing time and there is a pronounced risk for increase in pain and discomfort in the lower extremities and lower back. ...
... Beside Borg Scale and VAS, a survey form was also established to investigate discomfort and subjective fatigue due to standing at workplaces. Surveys using the Body Part Symptom form revealed that all respondents who performed jobs in standing position experienced discomfort and pain, and the frequency and level of discomfort occurrence are greater at lower extremities (Ahmad et al., 2006); (Taha and Majid, 2008). ...
Industrial workers were frequently exposed to injury at work due to an incorrect working posture. Improper working posture such as bending, twisting, overreaching, repetitive task and uncomfortable posture contribute to musculoskeletal disorder (MSD). This paper deals with the survey of the posture practices by Malaysian industrial workers. The questionnaire was distributed among 282 industrial workers. The survey was concerned with demographic detail, job specialization, industrial sectors, work and rest duration and the physical and mental condition during working time. It was found that over 93.1% of the workers facing the physical fatigue and 94.2% experienced mental fatigue while working. For the working posture it was observed that shoulder at chest level (30.1%), back in moderately bent forward (90.8%) and lifting heavy load 1 to 5kg (80.5%) are the major work postures practiced by most of industrial workers. Based on the statistical analysis there are significance correlation of the physical injury with the body injury among industrial workers. In conclusion, the specific working posture has yet to be determined for workers in industry. Therefore, this survey can provide a preliminary data for further research to ensure the correct working posture for worker.
... Fixed period were also identified as major contributors to MSD. Surveys using the Body Part Symptom form revealed that all respondents who performed jobs in standing position experienced discomfort and pain, and the frequency and level of discomfort occurrence are greater at lower extremities [18]. ...
This paper depicts the real situation faced by employees of Semiconductor Company Y at wire bond production line. The importance of ensuring prolonged standing considered as a serious matter was highlighted in the medical facts about the side effects of prolonged standing which is circulatory problems and standing symptoms. The objectives of this research are to identify the effect of prolonged standing during work, to assess the work method and to evaluate employee awareness of ergonomic issues. The data about pain were collected by using risk identification process that used an observation an interview to twenty employees of the company. From the interview result obtained, it was found that seventeen employees were suffered from sore feet and nineteen employees were suffered from back pain. Another step for proactive risk assessment is a direct observation, performed by ‘walk through’ inspection at the standing workstation areas. Risk assessment involved only wire bond operators in order to ensure that the data collected is accurate and valid which is involved fifty operators wire bond. Data Industrial Accident Prevention Association (IAPA) is derived from the production wire bonds. The (IAPA) Ergonomic Risk Assessment found that the operator of wire bonds in the company's exposure to risk indicators potential has been identified risk to an acceptable level. The result of evaluation showed that the level of employee's awareness was still low and an adequate and affective. Ergonomic management system need to be provided so that it will have a great influence to foster culture of awareness.
... Discomfort or subjective fatigue can be linked to psychological fatigue and it has been recognized as a factor in the decline of alertness, mental concentration, and motivation [6]. Usually, the psychological fatigue due to prolonged standing can be assessed subjectively through questionnaire surveys [7], use of the Borg Scale [8], use of the Body Part Symptom Survey form [9], or use of the Visual Analogue Scale [10]. Muscle fatigue on the other hand can be identified technically by observing the changes in amplitude and frequency of electromyogram (EMG) signals over time [11]. ...
... When signal amplitude increases and power spectrum shifts to a lower frequency, it indicates that the assessed muscles are in a condition of fatigue [12][13][14]. As recognized by many research works, surface electromyography (sEMG) is one of the reliable techniques that can be used to evaluate muscle fatigue [9,11,[15][16][17][18][19][20][21][22][23]. ...
... Throughout the 12 hours, the workers spent about 80% of the working time in standing position (only sitting during breaks). The long standing period has far exceeded the threshold limit of standing time [9]. Obviously, all workers have to stand because they require frequent movements and large degree of freedom to perform the process jobs. ...
The objectives of this study were to determine the psychological fatigue and analyze muscle activity of production workers who are performing processes jobs while standing for prolonged time periods.
The psychological fatigue experienced by the workers was obtained through questionnaire surveys. Meanwhile, muscle activity has been analyzed using surface electromyography (sEMG) measurement. Lower extremities muscles include: erector spinae, tibialis anterior, and gastrocnemius were concurrently measured for more than five hours of standing. Twenty male production workers in a metal stamping company participated as subjects in this study. The subjects were required to undergo questionnaire surveys and sEMG measurement.
Results of the questionnaire surveys found that all subjects experienced psychological fatigue due to prolonged standing jobs. Similarly, muscle fatigue has been identified through sEMG measurement. Based on the non-parametric statistical test using the Spearman's rank order correlation, the left erector spinae obtained a moderate positive correlation and statistically significant (r(s) = 0.552, p < 0.05) between the results of questionnaire surveys and sEMG measurement.
Based on this study, the authors concluded that prolonged standing was contributed to psychological fatigue and to muscle fatigue among the production workers.
