# Study on Quantitative Expression of Cycling Workload
## 2 Cycling Safety and Comfort-Formation Mechanism and Measurement Methods
### Measurement for Cycling Workload
A subjective scale method has advantages in that it is easy to collect the data and saves time and the method can account for differences in ability, state, and attitude [24]. However, subjective results alone are not satisfactory or realistic and it is difficult to accurately quantify the cycling workload using these results in isolation. The addition of objective physiological measures can compensate for the weaknesses of the subjective scale and make the results more reliable. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Cycling Workload Level** & **Subjective Scale Description** & **Cycling Performance** \\ \hline \multirow{3}{*}{Safe, comfort} & In the best condition; feeling energetic, awake, calm, free to ride, and quick to react & Plenty of riding space, the bicycle is safe and easy to handle, and it is easy to stay riding at a certain width \\ \hline \multirow{3}{*}{Safe, a little stressful} & Sober; can respond; a little more alert; able to deal with emergencies & Riding space is small and the handlebars of the bicycle \\ \cline{1-1}  & Cannot fully adapt to the road conditions; riding control is hectic, nervous, worried & Lack of riding space; large swing of the bicycle; difficult to control handlebars; need to use brake or stop \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Subjective scale for the cycling workload level. \begin{table}
\begin{tabular}{c c c} \hline \hline
**No.** & **Indicator** & **Items** & **Percentage (\%)** \\ \hline
1 & Content Feasibility & 2 aspects & 83 \\
2 & Evaluation & 3 aspects & 86 \\
3 & Efficiency and Effectiveness & 4 aspects & 90 \\  & Total & 9 aspects & 87 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Results of Subject-Matter-Expert Validation. 3 Physiological Indicator of Cycling Workload  
Although there is little specific research on objective physiological quantification measurements for dynamic cycling workload, the relevant research on driving workload can be referred, analyzed, and screened to choose a suitable indicator; regardless of whether one is assessing cyclists or drivers, the research subject for measurement is the same--human factors. The difference is that the chosen indicator for cycling workload must be applicable to both the mental and physical workload of cycling. Many physiological techniques such as electroencephalogram (EEG), electromyography (EMG), electrocardiogram (ECG), respiratory rate and electrodermal activity (EDA), have been adopted as measuring methods to quantify workload in different research fields [25; 26]. EEG has been commonly used in the aircraft field due to its sensitivity; however, the data are hard to interpret and EEGs are so sensitive that the results can be affected by several potential factors not related to workload [27]; EEG is not a fit measure for the driving field experiment due to operational problems [21]. EMG is an objective measurement tool that is mainly used in ergonomic and occupational fields to study muscle strain during work and make recommendations for work design [28]; it has been recommended for use in static cycling as mentioned in Section 1, but there is no evidence for its validity in assessing mental workload. EDA has been found to be sensitive to secondary tasks and therefore was recommended for workload measurement and prediction [29]. However, it has been proven to be sensitive only in sudden workload changes rather than in gradual ones [30] and EDA results are impacted by environmental temperature, which means it is unsuitable for field tests. ECG is the most widely used workload-measurement techniques in driving tasks [26]. Among all the ECG indicators, heart rate (HR) and heart rate variability (HRV) are the most commonly used ECG indicators to measure drivers' workload during a driving or tracking task [31]. Although HR is a common measure for cardiac monitoring, it has been reported that HR cannot measure absolute levels of workload, only relative levels [32; 33].