# Degree of Hamstring Extensibility and Its Relationship with Pelvic Tilt in Professional Cyclists
## 4 Discussion  
One of the main objectives of this study was to compare and correlate the pelvic tilt and the hamstring extensibility between different postures, both upright standing and maximum trunk flexion with extended knees, from a seated position and standing, as well as on the bicycle using the three most widely used handlebar grips by cyclists. The analyses revealed that professional cyclists exhibited a pelvic tilt when standing of approximately \(12^{\circ}\). However, in the Sit-and-Reach and Toe-Touch positions, the pelvis was positioned in retroversion. On the other hand, the pelvis significantly increases its anterior tilt as the support of the handlebars becomes more distal and lower in relation to the height of the saddle. Taking into account that the pelvis constitutes the foundation of the vertebral column, the current findings highlighted the influence of pelvic tilt disposition in cycling and thus sagittal balance in both normal and pathological conditions of the vertebral column [25]. The results obtained in the current investigation are consistent with previous studies analyzing pelvic tilt in cycling. A previous investigation analyzing spinal curvatures in competitive cyclists reported that in a standing position, the pelvic tilt showed a mean value of around \(15^{\circ}\)[26], which closely mirrors the findings of the current study. In addition, consistent with the findings of the present study, other authors noted that, on bicycles, the pelvis significantly increased its anterior tilt from the highest to the lowest handlebar grip [10]. However, no correlation analysis between the degree of hamstring extensibility and pelvic posture was performed by those authors. When analyzing pelvic tilt, the degree of extensibility of the hamstring is considered a reference since the origin of this musculature is located in the ischial bone. Thus, people with hamstring shortness may frequently exhibit a pelvis retroversion predisposition, while improving hamstring extensibility may be useful for decreasing lumbar flexion and increasing hip flexion when trunk flexion movements or stop lifting tasks are performed [27]. Therefore, examining the relationship between the degree of hamstring extensibility and pelvic tilt in the standing position and on the most commonly used handlebar grips in cycling is paramount to understanding the role of the pelvic position in cycling. In the present study, a significantly strong and positive correlation was observed between the degree of hamstring extensibility and pelvic tilt in the standing, Sit-and-Reach, and Toe-Touch postures. However, no strong or significant correlation was identified between the degree of hamstring extensibility and the three postures evaluated on the bicycle. Perhaps, due to the typical cyclist's position on the bicycle (knee not fully extended at the lowest point of the pedal stroke), the tension on the hamstring muscles at their ischial tuberosity insertion may be alleviated. This situation could justify the absence of a strong and significant correlation in specific bike positions, such as those observed in postures involving maximum trunk flexion with extended knees. Specifically, [PERSON] et al. [15] reported that cyclists had a greater anterior pelvic tilt capacity than non-cyclists. These authors justified their findings due to the greater adaptability of cyclists to trunk flexion postures. Similarly to the findings identified in the present investigation, [PERSON] et al. [19] observed a significant relationship between pelvic tilt in the Sit-and-Reach posture and the degree of hamstring extensibility, but not in postures adopted on the bicycle. In a recent study of well-trained road cyclists, [PERSON]