# A Review on Ergonomics in Agriculture. Part II: Mechanized Operations
## 4 Results
### Brief Review of Literature Classified into Agricultural Machinery Types  
#### 4.2.1 Tractor  
The tractor is an engineering vehicle that was specially designed for the purpose of providing the power to automate several agricultural tasks. Operating a tractor includes a variety of actions such  
Figure 5: Keyword information clustering of the relevant papers. as operating levers, buttons, clutching and braking pedals, steering and looking behind as a means to maneuver and observe the machine. The above acts influence the sitting posture and loading on the parts of the body. Prolonged sitting on the seat of tractors along with the aforementioned factors seems to contribute to MSDs that workers complaint for. Finally, it is widely known that operators are exposed to high doses of WBV during common agricultural operations originated from both the engine and the ground [20]. High levels of vibration lead to the discomfort of the operator and the increased risk for low back, shoulders, neck, knees and spinal pains. The probability of experiencing these kinds of discomforts seems to increase with age. The host of MSDs, coming from the use of tractors, justify the relatively large number of journal papers found in the literature within the last decade that are going to be presented below in brief. The importance of the anthropometric characteristics and isometric muscle strength was highlighted by [PERSON] et al. [54] and [PERSON] et al. [55], who investigated Indian and Iranian workers, respectively. In fact, the discrepancy between the existing standards for tractor controls and the real ones can lead to overexertion, which is a critical risk factor for the emergence of musculoskeletal injuries. In [54], the push and pull strength of the right hand as well as the strength of the right leg and foot were substantially higher as compared with their left sides. In [55], the results demonstrated the inappropriateness of the international standards. Furthermore, anthropometric features were used by [PERSON] et al. [56] as a means to improve safety through the adaptation of a steering panel. In particular, they measured the dynamic load of various body parts, such as the arms, wrists and forearms with surface electromyography by taking into account the steering column and the angle that is formed between the arm and the forearm. The results revealed that the most convenient position regarding the hands was at the elbow angle of 100\({}^{\circ}\) and when the inclination angle of steering column was close to 50\({}^{\circ}\). The measurement of WBV via triaxial accelerometers was the subject in [57] and [52] regarding farms in Poland and prariies in Canada, respectively. [PERSON] [57] evaluated the annual exposure to WBV in the x, y and z directions on the operator seat. It was noted that the highest total vibration doses took place in August and April, whereas the maximum mean daily exposure appeared during April, August, September and October. On one hand, the high values appeared in August were attributed to agricultural activities related to soil cultivation, cereal harvesting and transport. On the other hand, in April bedding and raking hay, spreading of fertilizers, disc narrowing, spraying and transport were responsible for the high vibration levels. Concerning [PERSON] et al. [52], they found that the maximal measurements were in the vertical axis. Interestingly, the 41.4% of the measurements in the vertical axis were within or above the caution zone of the health guidance. Furthermore, shocks occurred, which are considered to be the principal risk factor for the development of low back pain. The influence of implements, which can be added to the tractor, on the vibration levels was studied by [18; 58]. In [18], the longitudinal WBV occurring in tractors having a large square baler was assessed. Considerable WBV was observed during downhill driving with four-wheel drive. The authors suggested simple control of four-wheel drive operation for reducing the vibrations.