# A Review on Ergonomics in Agriculture. Part II: Mechanized Operations
## 4 Results
### Supopsis of the Methodologies, Ergonomic Interventions and Risk Factors for the Development of MSDs
Special versions of the WBV health surveillance questionnaire questionnaire [80] were adopted for gathering the mass, age and height of the participants as well as their experience on farming and operation of the machines. This type of questionnaire also collects data regarding the terrain of the farm, characteristics of the machinery, the distance, speed and duration of driving and work environment. It also involves the prevalence of various reported MSDs, including pains in the regions of neck, shoulders and low and  
Figure 6: Time distribution of the selected papers along with their citations during 2010-2019 according to a Google Scholar search conducted on 2 April 2020. Figure 7: Distribution of the different kinds of studied agricultural machines causing musculoskeletal disorders; abbreviation AMDSs corresponds to agricultural machines with driving seats. upper back. Nordic questionnaire was also implemented with the intention of determining whether MSDs were developed in a given population. Evaluation of the incidence pertaining to the nine selected body parts is taken into account. Participants answer to yes-no questions. On one hand, if the response is \"yes\", further questions follow dealing with medical intervention, duration and frequency. On the other hand, when a negative answer takes place, the participant continues to the next part of the body [81]. Finally, special questionnaires about the hazardous consequences of machineries operated by hands were identified in the present literature survey. These questionnaires are associated with the high levels of vibrations that are transmitted at the upper extremities as a result of the contact between the hand and the handles of the machine. Examples of this type of machineries are grass trimmer, rice plowing machine and handheld olive beater. Questionnaires can help to the filtering of MSDs for the purpose of producing useful results for the occupational health. However, it should be stressed that the role of questionnaires is not to offer medical diagnosis. Careful examination of the reported MSDs among a specific sample by experts can serve for optimizing the work environment and the seat, handle and other equipment design [82]. One of the weaknesses, which are associated with questionnaires, is that recent experienced MSDs are more likely to be remembered as compared with the older ones. In addition, it should be taken into account that MSDs are progressive and that participants can have some symptoms after physical findings [83]. The conditions at which the completion of the questionnaire takes place are very important and may influence the outcomes. For example, the presence of a researcher may affect answers. Additionally, it may be difficult for the questions to be phrased clearly and this could lead to different interpretations of questions. In order to quantify the muscle activity, electromyography was adopted in the reviewed studies. Understanding of when as well as how much the muscles are active during the mechanized operation can be advantageous for physicians, in an effort to comprehend the mechanism of the injury. Moreover, handgrip dynamometers were used for estimating the isometric hand and arm strength as well as various sensors for measuring the grip force and interfacial pressures. As can be gleaned from Table 3 and illustrated in the bar chart of Figure 8, the risk factors for the development of MSDs seem to be associated, to a great extent, with the \"vibrations\" (total percentage of 71.88%) which are produced either in the form of WBV (53.13%) or as HATV (18.75%). Biomechanics and physiological effects of vibration exposure were elaborated in the Section 2.2. According to the criteria presented in 3.3, there is a strong evidence regarding a positive relationship between exposure to vibrations and MSDs. In addition, some evidence exists for a positive relationship between \"personal characteristics\", such as mass, height and age and the pathogenesis of MSDs with a percentage of 18.75%.