# 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
The ergonomic interventions that were suggested by the authors of the reviewed articles are closely related with the risk factors which they identified, as can be seen in Table 3. In brief, multi-axial seat suspension systems and shock absorbers are recommended for attenuating the experienced vibrations. In general, an ergonomically designed seat and handle should lessen the  
Figure 8: Percentage (%) of the main identified risk factors causing musculoskeletal disorders. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Ref.** & **Main Results** & **Risk Factors** & **Authors’ Suggestions** \\ \hline \multirow{4}{*}{[52]} & The maximum vibrations appeared in the & \multirow{4}{*}{WBV} & Workplace information for the total \\  & vertical axis; 41\% of these measurements & & work period \\  & were within or above the caution zone & & \\  & Mounting/dismounting the tractor as well & & \\  & as awkward trunk postures seems to & & \\  & cause back pains; an additional step and & & \\  & near-view cameras and mirrors were & & overconfidence \\  & mentioned to be particularly helpful & & \\  & The vibrations on the seat along the x and & & \\  & y axes are affected by the pitching and & & \\  & rolling movements & & \\  & Ground roughness and engine generate & & \\  & vibrations within the 0–30 Hz and 50–200 & & \\  & Hz range, respectively, [PERSON] method & & \\  & better demonstrated the difference & & \\  & between the signals & & \\ \hline \multirow{4}{*}{In all experiments both the HATV and 33 OCRA scores indicated values beyond the admitted limits} & \multirow{4}{*}{HATV} & Use of reliable vibration data, not only \\  & Multi-axial suspension can decrease the & & \\  & lateral vibration and the associated pain & & \\  & in the neck and low back & & \\  & The vertical vibrations were higher at & & \\  & head and neck than the seat. & & \\  & Inappropriateness of the international & & \\  & standards in the case of the isometric & & \\  & muscle strength in Iran & & \\  & The most convenient position for the & & \\  & hands was at the elbow angle of 100\({}^{\circ}\) and & & \\  & when the steering column inclination & & \\  & angle was 50\({}^{\circ}\) & & \\  & The analyzed pressure indices are useful & & \\  & for comparing seats with the aim of & & \\  & assuring comfort in static and dynamic & & \\  & situations & & \\  & In few situations, some over the limit & & \\  & values were observed; 62\% of the & & \\  & participants reported some discomfort of & & \\  & the spine throughout the last 12 months & & \\ \hline \hline \end{tabular}
\begin{tabular}{c} HATV: hand–arm transmitted vibration; Ref.: reference; WBV: whole-body vibration.  
\end{table} 
Table 3: _Cont._transfer of vibrations from the agricultural machinery to the human body and offer a comfortable operation. Overall, the optimal performance and comfort of seating system entails covers, cushion, damping and suspension mechanisms. Decrease of the levels of vibration on the seat is a key factor towards comfort and attenuating of MSDs. This can be accomplished via adjusting the spring characteristics to complement the characteristics of the machine. Furthermore, cushions of the seat may help as shock absorbers. They should be designed so as to provide minimum load transmission. In particular, they can be selected to have a specific dynamic stiffness and can undergo a considerably large deflection to get the mass to rest [36]. Based on research outcomes, there is no consistency in the selection of a certain material with verified suitability. Moreover, design of tractor equipment based on anthropometric and isometric muscular strength data is suggested for avoiding awkward postures. Reduction of velocity and driving duration was also recommended for experiencing less vibration levels. Interestingly, most of the studies focused on the need for increasing the awareness of the risk factors associated with the subsequent MSDs among the workers, whose feedback is of major importance on evaluating the ergonomic interventions.