According to the collected data, performance improvement in the hurdles sprint involves a reduction of spatiotemporal parameters; this result corresponds with Graubner and Nixdorf’s study , which intends degrees of freedom reduction of system. Contrary to the findings of Tsiokanos et al. , the present study demonstrates that improved performance in the 110m hurdles sprint event depends on spatial and temporal parameters. In the support phase, the vertical force components are crucial, especially during the crossing of each hurdle . During the segments’ body transition, invariable and common characteristics can be distinguished. These distinctions are essential: both for the determination of universal mechanisms in the organization of hurdlers’ temporal and spatial movements and for solving problems related to the presence of the obstacle . This is of particular importance in combined athletics events, since participants are obliged to develop their technical skills in several athletic specialties at the same time. In contrast, the training efforts of hurdlers are focused on improving hurdling skills, refining hurdles sprint mechanics, and establishing general sprint conditioning, as well as on the even distribution of energy throughout the race. The resolution of such tasks can be expected to be even more successful when the general mechanisms constituting the basis of such combined events, or distinct technical elements of the same discipline, have been studied appropriately.
Our results also highlight the importance of increasing the sprint rhythm to improve 110m sprint hurdlers’ performance. This means that the velocity of running between and over the hurdles needs to be matched with the technique and agility of the runner. Agility itself depends on several factors, especially those that describe the attacking phase in front of the hurdle, the CM path, and the landing after the flight over the hurdle . Running speed could also be increased by optimizing support and flight time and reducing amortization time [17–19].
The present study confirms that EHS were distinguished from ED by their shorter stride length over the hurdle, lower CM path, and faster crossing technique. Thus, agility and fluency in running over the hedge was significantly higher in EHS. Coh et al.  found that elite athletes with shorter hurdle clearance times had faster hurdle running times. According to McDonald and Dapena , the criterion of an efficient hurdle clearance technique is the shortest possible time of the flight phase (hurdle clearance time); otherwise, the hurdler loses velocity in the air. According to Bubanj et al. , this condition is a very effective way to reduce the vertical oscillations of the CM since it allows the athlete to maintain a stable horizontal velocity and develop a consistent stride pattern. Our results, determined under experimental competitive conditions, were in accordance with the findings of Hanley et al.  performed in-competition in eight finalists from the men’s 110 m hurdles at the London 2017 World Championships. Our findings further reveal significant differences between ED and EHS in relation to the first stride post-hurdle that are related to the latter’s superior performance. This could be explained by the necessity for minimizing the braking forces to maintain a constant horizontal velocity along the race and enable a quick resumption of optimal speed between the hurdles . Indeed, it is widely accepted that one of the most important characteristics of the effectiveness of the hurdles sprint techniques is the ability to maintain a high and constant running rhythm without losing balance, especially after crossing the hurdle at the touchdown moment , and that the braking phase must be as short as possible . Moreover, a typical technical fault, particularly among novice runners, is the considerable loss of speed after the touchdown that leads to a substantial reduction of the horizontal velocity and amplitude of the first stride after the hedge [7, 24]. As such, it becomes clear that the optimal flight time in EHS during the recovery stride (post-hurdle) reflects a more efficient running technique . This underlines the finding of Li and Fu  that the first stride after the hurdle is a crucial factor that determines whether the hurdle clearance technique is satisfactory.
The comparative analysis of the angular kinematics reveals that EHS are distinguished by a more pronounced forward slope of the trunk at hurdle-crossing, particularly during the landing phase. This body posture at the landing phase creates auspicious conditions for an active landing after hurdle-crossing, minimizing the loss of speed mainly during the amortization phase, ensuring easier forward locomotion , and allowing the CM to lower to an optimal level above the hedge . It should also be noted that EHS show more efficient movement of the attack leg at the moment of propulsion and hurdle attack. In fact, the lead leg’s smaller knee angle reduces its moment of inertia at the attack of obstacle . According to Coh et al. , the leading leg increases the value of the horizontal CM velocity of the athlete at hurdle-crossing.