Possible Implications for Top Performers
David Oliver
David Oliver is very clearly the outlier among top athletes regarding flight time. Oliver is also a very clear outlier in terms of both build and upper body mass, potentially resulting in much greater required GRF’s and greater translation of the COM during hurdle clearance. The solution that Oliver displays seems to be the adoption of extreme postures to minimise flight time, however as per the above this strategy can easily result in excessive anterior translation of the centre of mass and a loss of rhythm at landing. This is clearly demonstrated in the video below of Oliver’s 12.89 in the overhead shots from 1:37. Oliver displays a collapse of posture to the right after clearing several hurdles due with landing on his right leg, and goes very close to stepping into the adjacent lane. Interestingly, a lateral shift is also seen from the blocks. Despite being a far superior performer to his competitors in this race, Oliver shows the greatest lateral oscillations of anyone in the race, suggesting lower stiffness/co-ordination.
While it may be drawing a long bow, I am interested at the large improvements and drops in performance displayed by Oliver over the past few years, as potentially a technical model which relies heavily upon force production and extreme postures as opposed to efficiency and rhythm will be harder to maintain/less reliable.
Dayron Robles
Dayron Robles is the intermediate between Oliver and Terrence Trammell in the Doha flight time data, with interesting trends across the race vs Trammell (more below re Trammell). He is obviously a tall athlete with a high COM and possesses a slighter build than Oliver. Most would describe Robles to the naked eye as being exceptionally smooth and rhythmical in technique. The side on shots from 2:24 below show exceptional recovery of posture following hurdle clearance:
There is a very interesting comparison of Robles’ and Oliver’s hurdle clearance in slow motion at 1:31 below, even though Robles’ hits the hurdle Oliver’s more extreme head and trunk position is fairly clear:
The authors here (https://w4.ub.uni-konstanz.de/cpa/article/viewFile/4836/4476) show some great methodology and data, but I would disagree with their conclusion that “This study proposed that Robles could improve his performance by reducing the flight time in the hurdle clearance. The direct transfer of the results of this research to Robles’ coach produced technical improvements in the athlete, which were materialised in the IAAF World Indoor Championships in Doha 2010, at which Robles was victorious.” As the Doha data suggest that flight time did not necessarily discriminate.
Along the lines of Milan Coh’s findings, I would more readily believe that Robles’ flight time is an artifact of optimised 3-dimensional kinematics during hurdle clearance and landing, allowing maximum efficiency during landing and rhythm thereafter, which manifests in shorter ground contact times and longer step length.
Robles vs Liu Xiang and Terrence Trammell
Robles is a little taller and likely has a higher COM anatomically than both Liu Xiang and Terrence Trammell. As per the above, these athletes can either compensate through a combination of
i) Greater GRF’s to clear the hurdle with a given posture/step length.
ii) Greater postural deviation of joints including the head and neck, arms, trunk, lumbopelvic region, knee, ankle and foot to clear the hurdle with given GRFs and step length.
I would suggest that Liu compensates through both but in particular postural changes in terms of lead arm and knee position relative to the hips (more flexion and abduction), and Liu appears to display the mobility and skill to modify his posture in a manner that does not induce excessive anterior translation of the COM and a loss of rhythm at contact during landing of the hurdle clearance step.
Trammell is extremely fast over the flat sprints, with lifetime PR’s of 6.45 for 60, 10.04 for 100m. He is also marginally shorter than Robles’. I think Trammell very likely compensates through increases in ground reaction forces, which his flat times indicate have a very high potential. However, to maintain rhythm through increased take-off and braking GRF’s at landing from the hurdle clearance rather than through changes in posture and skill, while maintaining ground contact time, involves greatly increased metabolic cost.
I do not think this strategy if evident is sustainable over the 110m hurdle distance and will likely induce premature fatigue, and Trammell’s 60m hurdle credentials against the likes of Oliver, Robles and Liu are slightly disproportionate in comparison to his competitiveness at 110m outdoors.
The IAAF Doha data indicates that Trammell’s flight time is much higher than Robles through the race, and while Robles sees decreases in flight time from hurdles 1-4 this is less evident for Trammell, perhaps indicating Trammell is not building rhythm and velocity from increased momentum as the race progresses. The plot of speed vs race stage shows clear separation of the lines for each athlete between middle of the race. Data from https://www.hurdlecentral.com/Docs/Hurdles/2008_US_OlympicTrials_HurdleTouchdownTimes.pdf on Trammell vs and in form Oliver shows the following touchdown times for hurdles 1-10 at USATF 2008:
Oliver: 2.57, 1.02, 1.01 0.99, 0.98, 0.99, 0.99, 0.99, 0.99, 1.04
Trammell: 2.52, 1.02, 0.99, 1.01, 0.98, 1.00, 1.01, 1.01, 1.02, 1.03
While we don’t have reaction time, it seems very likely that Trammell had advantages over Oliver during the initial portion of the race (especially due to superior GRF’s out of the blocks at the start), which dissipated as the race continued and fatigue accumulated. There is also Osaka 2007 where he lost ground to Liu in the latter stages:
And again in Berlin 2009, subtle but decisive gaps seemed to open over the last few hurdles: