After conducting 20 practice trials of cycling in straight and narrow path tasks daily for 2 days, the deviation rate on the retention test was observed to be decreased compared with the pre-test, confirming practice effect. This task is considered suitable for evaluating cycling skills because it has been reported that experienced cyclists have less deviation than beginners when riding on a straight line3. Therefore, a reduced deviation from the path indicates an improvement in cycling skills. Moreover, the cycling speed in the retention test increased compared with that in the pre-test. This is attributed to a speed-accuracy trade-off19, indicating that human movement time increases in highly challenging tasks. Therefore, unfamiliar tasks (such as cycling on a narrow path) might lead to a slower cycling speed in the pre-test, whereas getting used to the task might lead to an increase in cycling speed in the retention test.
Regarding body and bicycle movements, the results of paired t-tests between the pretest and retention tests demonstrated that the variability in steering angle, RMS of angular velocity, and variability in frame roll angle decreased in the retention test compared with the pretest. These results support our hypotheses. Previous studies have established that experienced cyclists perform steering and frame rolling with smaller variability and velocity than novices do2,3. In this study, the comparative results before and after practice revealed that improvement in skills leads to smaller steering and frame roll movements.
Regarding gaze behaviors, the results of paired t-tests between the pre- and retention tests showed no significant difference in gaze angle between the pre- and retention tests. The unexpected results regarding the gaze angle could be attributed to individual variations in participant gaze strategies. Some participants who initially focused on the path shifted their gaze towards the goal, whereas others who directed their gaze towards the distant path shifted their gaze towards a closer area. Therefore, to achieve high performance on straight and narrow paths, individualized optimal gaze distances may be necessary. In the retention test, compared with the pre-test, the IQR and range of head pitch decreased. These results support the hypothesis that maintaining stability in head movements, which is related to balance, is crucial for cycling6,7,8.
Contrary to the hypothesis of increased OKN, the results of the paired t-test for OKNfreq between the pretest and retention tests did not display significant differences. The reason for this is the relatively short duration of the practice sessions. Previous studies have demonstrated an increase in OKR gain through sustained visual stimulation for 1 h daily over 5 days15 and an increase in OKN frequency through sustained visual stimulation for 15 min daily over 21 day16. In contrast, this experiment involved 40 trials, suggesting that the practice duration might not be sufficient for a noticeable increase in OKN.
Multiple regression analysis revealed that different explanatory variables were included in the pre- and retention tests. In the pre-test, the variabilities of steering, head angle, OKNfreq, and cycling speed were included. The results indicated that a smaller variability in steering contributed to a lower deviation rate. Previous study5 suggested that handlebar use is crucial for learning to ride bicycles without assistance. In this study, all participants practiced using unfamiliar bicycles (BMX). Therefore, participants might be more dependent on handlebars for bicycle stability control. Furthermore, the results indicate that lowering the head and cycling at a slow speed contributed to a lower deviation rate. It is possible that a speed-accuracy trade-off occurred in the early stage19; therefore, cycling slowly while lowering the head might be related to the low deviation rate. Moreover, the results indicated that a high frequency of OKN contributed to a lower deviation rate. OKN consists of repetitive OKR, which is considered to compensate for vision instability20. Therefore, the high frequency of OKN possibly plays a role in maintaining visual field stability and improving cycling stability.
Conversely, in the retention test, multiple regression analysis showed that the variability in head roll tilt, head angle, head angle range, and OKRdur were included. These results indicate that a smaller variability in head roll and pitch is associated with a low deviation rate. Therefore, employing a control strategy that minimizes head movement is crucial. Furthermore, a smaller temporal variability in periodic eye movements corresponded to a low deviation rate, indicating that maintaining a consistent eye movement pattern might also hold significance. Moreover, the head angle was consistently included as an explanatory variable in both the pre- and retention tests, indicating that the deviation rate was smaller when the head was lowered regardless of skill level. One contributing factor to this phenomenon was the nature of the task, where participants were instructed to refrain from deviating from the narrow path. Previous study10 found that the proportion of individuals focusing on the path increased during cycling on narrow roads. Therefore, lowering the head could be deemed crucial for maintaining cycling stability along a narrow path. In summary, in the process of acquiring stable riding skills, minimizing variability in both head and eye movements was regarded as significant.
Comparing the multiple regression analyses of the pre- and retention tests suggested that the crucial control variables differed between the early and subsequent stages of the learning process. In the early stages, control primarily relied on minimizing the variability of steering. However, during the subsequent stage of learning, control primarily relied on stabilizing head movements, which contribute to overall body balance. This suggests that cyclists transitioned from relying on arm-based control to adopting whole-body control as their skills improved.
Limitation and future perspectives
One limitation of this study is the potential for further improvement in skill development. The participants in this experiment were individuals without prior experience in cycling competitions, equivalent to novice cyclists. Therefore, 40 trials over the course of 2 days might have been insufficient. Increasing the frequency of practice trials and improving skills could help elucidate the distinctive features of proficient cycling more effectively.
Practical applications
In unfamiliar bicycle or environmental settings, individuals tend to tense their arms and depend on steering. Based on the findings of this study, avoiding excessive reliance on steering control and instead prioritize the management of overall body stability, particularly by maintaining stability in head movements, is crucial. Additionally, periodic eye movements, such as OKR, may contribute to cycling stability.