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Volume 28, Issue 2 (Spring 2022)                   Intern Med Today 2022, 28(2): 186-201 | Back to browse issues page


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Emkani M, Jafari M, Mafakheri Lale Z, Tabrizi A. Evaluation of Muscle Fatigue and Determination of Risk Factors of Musculoskeletal Disorders Among Saffron Harvesters in Gonabad in 2017. Intern Med Today 2022; 28 (2) :186-201
URL: http://imtj.gmu.ac.ir/article-1-3668-en.html
1- Department of Occupational Health, Student Research Committee, Faculty of Health, Shiraz University of Medical Sciences, Shiraz, Iran.
2- Department of Occupational Health Engineering, Social Determinants of Health Research Center, Faculty of Health, Gonabad University of Medical Sciences, Gonabad, Iran.
3- Department of Occupational Health, Student Research Committee, Faculty of Health, Gonabad University of Medical Sciences, Gonabad, Iran.
4- Department of Occupational Health Engineering, Social Determinants of Health Research Center, Faculty of Health, Gonabad University of Medical Sciences, Gonabad, Iran. , tabrizi9@gmail.com
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Introduction
Agriculture is an occupation that predisposes people to health problems, especially musculoskeletal disorders (MDSs). MSDs are common in farmers due to the high workload in agriculture. These disorders are increasing as a specific risk of agricultural occupation. This job is one of the most widespread and dangerous job activities engaging about 63% of the population of developing countries [1]. The estimated lifetime prevalence of MSDs among farmers has been reported 90.6%, and the one-year prevalence of MSDs has been reported 76.9% [2]. Due to the inappropriate postures of people’s bodies, while performing duties, MDSs are an integral part of this job and almost all farmers suffer from these disorders [3]. These conditions include bending, kneeling, crawling, and twisting to one side and repetitive work that will result in physical stress. According to the available statistics, the rate of MSDs among farmers is 50% higher than among non-farmers [4]. According to previous research, MDSs related to work are the main causes of loss of work time, increase in costs, and human injuries in the workforce and are one of the biggest occupational health problems in the world [5]. These disorders include the involvement of a group of nerves, tendons, muscles, and supporting structures of the body, such as the intervertebral disc that can cause symptoms, such as pain, numbness, tingling, reduced work productivity, loss of work time, and temporary or permanent disability [6]. Age, height, weight, gender, smoking addiction, and physical activities can play a role in the symptoms of these disorders [7]. Tall people are more likely to suffer from back pain, and in general, the risk of suffering from such disorders is higher in obese, very tall, and very small people than in average people. Also, old people are more at risk of contracting these diseases than young people [5]. Among the important physical risk factors causing such disorders, we can mention unfavorable physical conditions, non-standard work environment, repetitive daily movements, and duration of work [8].
Agriculture jobs are the third most dangerous job in the world after working in mines and road and construction industries. Studies have shown that MDSs are very expensive from an economic point of view. Among these disorders, back pain is in the first place in terms of prevalence [9]. In a study conducted on 114 workers of green tea farms, it was observed that 72% of these people had a complaint of back pain, which is due to the lack of adequate occupational health care during work [10]. 
One of the problems of saffron farm workers is the low level of awareness, which causes workers to use inappropriate postures during saffron harvesting [1]. In a study conducted by Sadeghi et al. among saffron growers in Gonabad city, the physical condition of the majority of saffron harvesters was ergonomically at a very high-risk level, and the need to use methods to immediately correct their body condition was suggested [3].
Muscle fatigue is one of the muscle processes. As a result, the metabolic and neuromuscular function is reduced to continue the activity and muscle contraction cannot be maintained for a long time [11]. Excessive use of muscles, nerves, or joints leads to muscle fatigue, which occurs in continuous activities. It is believed that muscle fatigue provides the background for MSDs [12]. Since the improper position of the body during work is one of the most important risk factors for MDSs, in many methods of assessing the risk of suffering from MSDs, posture evaluation is considered the basis of evaluation [13]. One of the methods of assessing body posture, which is known as a functional work evaluation technique, is the muscle fatigue evaluation (MFA) method, which was developed by Rodgers in 1978 to describe workers’ discomfort [14]. Muscle fatigue caused by physical work reduces muscle strength, causes pain and discomfort, and for a long time, increases the probability of cumulative trauma disorders. Body fatigue decreases the body’s resistance, and as a result, the person’s desire to perform daily activities decreases. The increase in time and the number of repetitive tasks are one of the factors that increase the risk of cumulative trauma disorders. Because workers monitor their fatigue, it would be a desirable and appropriate method to estimate the amount of accumulated fatigue in a task [15].
MFA has an evaluation worksheet and determines the priority level of corrective measures for different areas of the body, including neck, shoulder, waist, arm/elbow, wrist/fingers, knee, ankle/heel [16], which is defined as low, medium, high, and very high to present control solutions. In this method, the level of effort, duration, and repetition in different areas of the body are evaluated and these risk factors are among the effective factors in the occurrence of MSDs. The validity and reliability of this method have been confirmed [15]. Also, the Nordic questionnaire is used to check the prevalence of symptoms of MSDs. The validity and reliability of this questionnaire have already been examined by Choobineh et al. [17].
Motamedzade et al. investigated the risk of MSDs in assembly workers using MFA and the Nordic questionnaire. The results of their study showed that both methods showed the highest risk of MSDs in the waist and the knee [18]. Jabari et al. investigated muscle fatigue and risk factors of MSDs in 165 tailors in Shiraz using the MFA method and the Nordic questionnaire. The highest prevalence of symptoms of MSDs was observed in the lower back at 57%. According to the MFA method, the highest percentage of people who were placed in the priority level of corrective measures was related to the waist area [19].
Regarding farmers working to collect saffron flowers, due to the type and nature of the work and the location of saffron flowers that grow on the ground, the farmer is placed in unfavorable conditions, such as sitting on his knees, bending, turning his back, and doing intense repetitive work. Paying attention to the limited harvest time, which is done in one month of the year, they experience stress, physical load, and muscle fatigue during harvest. Currently, saffron harvesting is done among farmers according to traditional methods. So far, various studies have been conducted on farmers to investigate MSDs and provide solutions to reduce them [202122232425], but no specific study has been done to find out about the muscle fatigue of different parts of their body while doing work [3]. Considering that the largest amount of saffron planting and harvesting takes place in Iran, foreign and domestic articles that deal with the problems of workers in saffron cultivation fields are very limited, and special measures are needed to prevent the occurrence of musculoskeletal problems caused by working in these fields. Therefore, this study was conducted by using the MFA method to evaluate body muscle fatigue and determine the parts of the body that have the worst conditions and determine the risk factors of MSDs in saffron harvesters in Gonabad farms.
Materials and Methods 
In this cross-sectional study, 84 saffron harvesters from Gonabad city participated in the research. This study used a simple random sampling method. The following Equation was used to estimate sample size (Equation 1): 


p: In a study conducted by Jabari et al. [19] evaluating fatigue among tailors in Shiraz city, it shows that 46.7% of them have a high risk.
d: The level of accuracy that is considered to be 10%.
Those who had a history of mental illness and acute musculoskeletal problems or accidents affecting the musculoskeletal system were excluded from the study.
Also, the data collection tool in this study was completed by trained personnel after the necessary guidance to the participants. The study was conducted after harvesting saffron by the participants.
Research tools
Demographic information questionnaire: This questionnaire includes items, such as age, height, weight, gender, medical history, work history, working hours, and smoking.
Nordic Questionnaire: To investigate the prevalence of symptoms of MSDs in the neck, shoulder, back, waist, elbow, wrist, hand, thigh, knee, and foot, this questionnaire was used, which includes two parts of personal information and questions. 
MFA posture evaluation worksheet: This method was used to evaluate muscle fatigue. In this method, all areas of the body, such as neck, shoulder, back (waist), arm/elbow, wrist/hand/fingers, leg (from thigh to leg)/knee, and ankle/foot/fingers are evaluated. This worksheet includes three variables: Level of effort, duration of effort, and repetition of effort, which is given a score of one to three for the level of effort, and a score of one to four for the duration of effort and repetition of effort. The scores are summed and form a three-digit number, which finally defines the priority level of corrective measures as low (L), medium (M), high (H), and very high (HV). The validity and reliability of the MFA muscle fatigue assessment chart have also been confirmed in national studies [15]. 
Finally, the data was analyzed using SPSS 20 statistical software. Descriptive statistical tests, Chi-square test, and independent t-test were used for data analysis.
Results 
A total of 84 saffron harvesters participated in this study, half of them were women and half were men. In sum, 68.7% of the participants exercised and 31.2% did not exercise. In addition, 25% of the participants had a history of non-occupational illness and 75% of the participants had no history of non-occupational illness. Totally, 75% of the subjects were non-smokers and 90% (72 people) were right-handed. The average age of the participants in this study was about 45.67 years and the average body mass index (BMI) of the farmers participating in this research was 22.7kg/m2. The average weight of the participants was 75.44 kg, their average height was 176.85 cm, the average work experience of the participants was 62.54 months, and the average daily working hours of the participants was 8.34 hours. The prevalence rate of MSDs in the last 12 months in nine areas of the body is shown in Table 1.


As shown, most of these symptoms are related to the ankle and the least related to the neck.
 Table 2 presents the results of the MFA method.


The highest percentage of areas of the body that are at a very high level of muscle fatigue was in the neck area and the wrists.
The results showed that there was not a significant relationship between MSDs in the elbow, wrist, thigh, and knee areas and age, in the neck, shoulder, ankle area, elbow, upper back, and lower back areas and gender, and in the upper and lower back area, thigh, and knee and the history of the disease, and the wrists and the number of working hours (P<0.05). Also, there was no significant relationship between MSDs and exercise, BMI, and smoking (Table 3).


Also, the findings showed that there was a significant relationship between muscle fatigue in the shoulder area and age, in the left shoulder area, left arm, and left leg and smoking, and in the right wrist area and exercise (P<0.05). There was no significant relationship between body muscle fatigue and gender (Table 4).


Discussion 
Based on the results of this study, saffron harvesters are exposed to MSDs due to the type and nature of their work. In this study, most of the participants were in the age range of 45 years, among which a high prevalence of MSDs was seen due to their age and non-ergonomic conditions of the work environment, and improper body posture during work.
In the study by Izadirad et al., [24] the results showed that the prevalence of MSDs in workers and farmers is very high, and in the last 12 months, 72% of farmers and 83.33% of workers reported MSDs in one or more areas of their body.
The results of this study showed that the highest prevalence of MSDs or the highest risk of MSDs in saffron harvesters is in the ankle, shoulder, and wrist areas because the saffron harvesting is done in a sitting position, and as a result, most of the upper limbs and legs are involved.
A study by Golbagh et al. in 2020 on female assembly workers showed that 76% of workers had MSDs in at least one of their organs. The back, right wrist, neck, and then right shoulder had the highest prevalence of MSDs based on the findings of the Nordic questionnaire. These people with more than 15 years of work experience and an average age of 37.73 years had the highest percentage of risk in the right wrist and waist with a frequency of 66.7% and the neck and right shoulder with a frequency of 60% [26]. The results of this study are consistent with the present study, considering the type of work that involves most of the upper limbs.
Hooshyar et al. assessed workers of fig gardens with an average work experience of 26.4 years, using the body map method, and most disorders were observed in the knee, sitting, and waist areas, followed by feet and hands [27]. Also, in the study by Maedeh et al., more than 50% of strawberry and eggplant farmers complained of back and shoulder pain due to bending over while picking strawberries and eggplants [28]. Rosecrance et al. [29]observed that 37.5% of farmers complained of back pain, 25.9% of shoulder pain, 23.6% of knee pain, and 22.4% of farmers complained of neck pain. It is somewhat consistent with the present study, and the reason for the difference observed in the results of these studies with the present study can be due to the difference in work history and the type of tasks investigated. Ghasemi et al. [8] observed that 90% of rice farmers have pain in the arms, shoulders, thighs, knees, legs, wrists, and soles, 70% in the neck, 40% in the elbow, 90% in the wrists and fingers, 70% in the upper back, and 100% in the lower back. The results of Rahimi’s study and Kalte et al.’s study [30] are somewhat consistent with the present study; but, the results of this study are not consistent with Amiri’s study, which shows the highest prevalence of disorders in the waist and thigh areas [31].
On the other hand, the findings of this research showed that there is a significant relationship between MSDs in the elbow, wrist, thigh, and knee areas and age, which is based on the studies by Rashidi et al. [32], Choobineh et al. [5], Mostaghasi et al. [33], Abedin et al. [34], Nasab al-Hosseini et al. [35] and Izadirad et al. (Aqqla Golestan) agree [24].
Also, there was a significant relationship between MSDs in the neck, shoulder and ankle, elbow, upper back, and lower back regions and gender, similar to the study by Abedini et al. [34]. The existence of a significant relationship between MSDs in the upper and lower back thigh, and knee regions and the history of the disease was consistent with the results of Amiri et al. [31].
Also, there was a significant relationship between wrists with the number of working hours, which is consistent with the studies by Choobineh et al. [5] and Dehghan et al. [36]. There was no significant relationship between MSDs in saffron harvesters and BMI, which is consistent with the results of Arghami et al. [35] and Motamedzade et al, [13] but not consistent with those of Bolghanabadi et al. [36]. Also, there was no significant relationship between MSDs and smoking, which is not consistent with the results of Choobineh et al. [5] and Dehghan et al. [36] The difference in the results of different studies may be due to differences in the age range, gender, number of participants, and the type of tasks investigated.
The results of many studies, such as Brake et al. conducted in 2001 confirm that fatigue is an inhibiting factor in many tasks and will reduce productivity [40]. The results of the MFA evaluation showed that the risk of suffering from muscle fatigue in the neck, right wrist, and right arm areas are very high in 84%, 42%, and 31% of the workers, respectively. The obtained results showed that most of the saffron harvesters were right-handed. In the study by Omid Kalte et al. on loading workers in a brick factory using the MFA method, the results showed that the upper parts of the body bear the highest amount of load when carrying bricks, and there is a possibility of MSDs in these parts due to the high fatigue caused by carrying loads [30]. The results of this study are consistent with the present study, considering the type of work that involves most of the upper limbs. Also, the analysis of the results showed that there was a significant relationship between muscle fatigue in the shoulder area and age, in the left shoulder, left arm, and left leg and smoking, and in the right wrist and exercise. But there was no significant relationship between muscle fatigue of body organs and gender.
This research was conducted on both men and women and the results were compared in these two groups. Also, questionnaires were completed by trained people, which is one of the strengths of this study.
The limitation of this research is the use of a self-report questionnaire possibly influencing answers by incorrect answers. To deal with this issue, the participants were given the necessary instructions while completing the questionnaires. Also, to comply with ethical considerations, the full consent of participants in the study was taken and the participants were assured that the questionnaires are anonymous and the data are confidential.
Conclusion 
All over the world, a significant number of farmers suffer from MSDs. The results obtained in this study showed that according to the information obtained from the Nordic questionnaire, age, disease history, gender, and working hours of people are MSDs risk factors. According to the results of the MFA assessment, age, smoking, and exercise are MSD risk factors. Because the prevalence of MSDs in saffron harvesters is at a high level due to the limited harvest time, which is done in one month of the year with not enough time to rest, it is necessary to take measures to prevent these disorders. Considering that education plays a significant role in reducing MSDs in farmers, these disorders can be prevented by raising the level of awareness of farmers in the form of educational programs. It can also be done by performing soft movements and professional ergonomic interventions to correct body postures related to work and using appropriate equipment, such as the trolley device, which was seen in the study by Abbaspour Fard et al. that prevented the occurrence of these disorders and provided the basis for increasing productivity and reducing MSDs.

Ethical Considerations
Compliance with ethical guidelines

This study was registered as a research project number 96/31/GMU in the Student Research Committee of Gonabad University of Medical Sciences. Also, this study has the ethics code number IR.GMU.REC.1396.94 from the ethics committee.

Funding
This research was financially sponsored by the Student Research Committee of Gonabad University of Medical Sciences.

Authors' contributions
All authors contributed to the initial idea and design, data collection, data analysis and interpretation, and initial writing or revision of the article. With the final approval of this article, everyone accepts responsibility for the accuracy and correctness of the content contained in it.

Conflicts of interest
The authors declared no conflict of interest.

Acknowledgements
The authors express their gratitude to the management and the staff of the Student Research Committee of Gonabad University of Medical Sciences.


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Type of Study: Original | Subject: Basic Medical Science
Received: 2021/06/22 | Accepted: 2022/04/3 | Published: 2022/04/1

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