# A Review on Ergonomics in Agriculture. Part I: Manual Operations
## 3 Results
### Identification of the Main Risk Factors for the Development of MSDs
Furthermore, a field investigation during the harvesting of tomatoes by [PERSON] and [PERSON] [87] found similar results by introducing a rest break of one minute after every eleven minutes of labor. As it was highlighted above, the repetitive nature of agricultural tasks, which appeared in several of the selected papers (29.6%), enhances the probability for developing MSDs. Fatigue of muscles and joints is the way of the body telling us to alter our working pattern. Performing the same movement over and over again, by also using certain and usually awkward postures, seems to provoke inflammation and pain. Besides, most of the time, agricultural workers have to keep the neck and shoulders in a fixed position for the purpose of exerting some force required for the task. Awkward postures include twisting of the wrist or arm and overexertion. Repetitive motion disorders normally occur in the wrists, hands, elbows, and shoulders. However, they can also take place in the back, neck, and ankles. Repetitive fatigue in hip and knees can lead to painful OA that is very common in rural workers, as it was elaborated in the section of \"Introduction\". The third most reported risk factor, with prevalence of 22.2%, was age. In general, surveys have demonstrated higher frequency of reported MSDs for older farmers than younger ones. Many times, agricultural workers leave their job owing to suffering from MSDs. There is also a number of them who continue to work after retirement, especially in small and family farms. According to [PERSON] et al. [88], biological changes associated with the aging process, namely, degenerative changes of ligaments, tendons, joints, and muscles, can result in the pathogenesis of MSDs. An overload regarding elderly farmers can be initiated because of the limited physical work capacity comparing to required workload. This may exacerbate the pathogenesis of MSDs [89]. As a consequence, older workers are more likely to have injury complaints when compared with the younger ones. The fourth most stated risk factor with incidence of 14.8% was the heavy carrying and lifting (abbreviated as HCL in Figure 6). This type of manual operation entails prolonged heavy work which needs a lot of energy and strength. In the case of particularly bulky and heavy loads, even though a worker is able to lift the burden, strains are concentrated on the lifting contact, namely, the hands or fingers. Even in agricultural activities that do not involve heavy lifting, repetitive movements can increase the risk of MSDs [16]. Some commercial products exist with the aim of reducing loads on low back during trunk bending by transferring load towards the legs. These ergonomics products are called weight (or load) transfer devices and have been the subject of the articles authored by [PERSON] and [PERSON] [35; 44; 45; 46]. Moreover, two ergonomic interventions, namely, \"ergo bucket carrier\" and \"easy lift\", were successfully tested so as to handle water with buckets, which is very common in farms. Finally, an ergonomically designed bag was successfully tested instead of the currently used tied basket around the waist in coffee harvesting [47]. Figure 6: Incidence (%) of the main identified risk factors causing MSDs. The abbreviations HCL and BMI correspond to Heavy Carrying and Lifting and Body Mass Index, respectively. Gender and kneeling were presented with equal prevalence (11.1%). Regarding the former, gender differences in the development of MSDs have been consistently reported in epidemiological investigations [90]. For instance, women tend to have higher endurance, whereas they are more susceptible to movements that are low-load and repetitive. Besides, for the purpose of compensating their weaker strength, they may use the muscles at levels near their maximum capacity. The selected papers showed that women are more vulnerable to MSDs. As far as kneeling is concerned, which takes place during ordinary operations, such as harvesting, planting, weeding, and lifting, it can also lead to MSDs.