Striding analysis raises serious stamina concerns for leading Derby contenders
It is always interesting to observe how people react when confronted with a methodology that they are unfamiliar with. Some are curious and want to learn more. Some approach the subject with a healthy scepticism. Others are aggressively dismissive, affronted at the notion that an avenue they are unfamiliar with might prove be of real use.
I experienced the full range of reactions when given the opportunity to discuss striding analysis for the first time on the ITV Racing coverage of the Oaks and Derby last year.
"They have to get up the gears, drop the revs and be fuel efficient"
📊 From stride patterns to pace, @kevinblake2011 with a fascinating deep dive into the Derby data#ITVRacing | #EpsomDerby pic.twitter.com/9seiFinLYf
— ITV Racing (@itvracing) June 1, 2024
It should be said that striding analysis is a long way from being new. Simon Rowlands has led the way in terms of public-facing work by integrating it into his analysis on this website for many years and others did fascinating work on the subject prior to that. Personally, striding analysis has been a daily part of my analytical work for many years now, albeit only occasionally appearing in my public-facing work. What slowed the progress of this analytical area was that manually harvesting the data via slow-motion video analysis was extremely laborious, but the availability of striding data for every race in Britain and Ireland via Total Performance Data and RaceIQ in recent years has served to speed up the rate of progress in this space in no uncertain terms.
So, while this brand of analysis isn’t new, it is still largely unexposed to a wider audience and the viewers of ITV Racing are the broadest racing audience that we have in British and Irish racing. It was a gratefully received opportunity to be given as much time as I was to delve into such a numbers-heavy and unfamiliar subject last year. Despite the inevitable pockets of scepticism and dismissiveness, it seemed to go down very well with the audience. It certainly helped that the main conclusions of the daily segments worked out well on the track in the shape of notable negatives for the likely stamina of Oaks favourite Ylang Ylang and Derby fancy Dancing Gemini as well as a big positive for City Of Troy in the Derby, but I’d like to think that most people would have found it interesting regardless of the outcomes (yeah, right).
So, it’s that time of the year again - here we go.
What makes the use of striding analysis so useful when it comes to the Epsom Classics is that they represent a completely different physiological test than most of the runners in them will have ever experienced in their careers. In some cases, they will see horses racing over a 50% longer distance than they have before. In all cases, they will be facing into an uphill climb of 41 meters in the first five furlongs that is unique amongst all Group 1 tracks in the world.
Typically, there are big gaps between what we know and what we don’t know about the prospects of the individual runners being effective over a mile-and-a-half at Epsom. We have all sorts of traditional means to assess this such as race reading, form and pedigree analysis, but stride analysis powers up the process and can add otherwise unseen or underappreciated nuance into the equation that can change conclusions.
It is a general rule of thumb with stride analysis that while a horse’s stride length is very adaptable to track topography, ground conditions and the tempo of a race, stride frequencies don’t tend to move as much. The shape of their distribution can alter in response to different race tempos, but what a horse is capable of in terms of a maximum and minimum stride frequency tends to be established after a few races and doesn’t widen all that much if at all throughout their careers. With stride frequencies generally correlating with trip preference (faster striders want shorter trips and vice versa) across a vast sample of data, this is what makes them such a useful tool when evaluating a horse’s likely suitability to a new distance. Outliers can be found, usually when dealing with those at either extreme of the scale in terms of physical size which can be accounted for when that information is known, but in the main I have found them to be a very informative piece of the puzzle.
What I have also observed over the years in the specific case of the Epsom Classics is that the course and distance represent such a different test for these young horses that some of them will show a different side to themselves in terms of their stride frequencies. Plenty will exhibit a lower maximum stride frequency in the Epsom Classics than they have in their runs leading up to it, but it is much rarer for a horse to show a notably lower minimum stride frequency than they have before. It can happen, but it is rare.
Thus, it is the minimum stride frequencies that I hone in on when it comes to the Epsom Classics. The 41-meter rise in the first five furlongs is so severe that if a horse cannot drop their stride frequency and respiration rate (stride frequency and respiration rate are directly correlated on a one-for-one basis) to conserve energy during the climb and then again in the downhill middle section of the race, they will generally pay for it in the closing stages. These are the physiological realities behind the majority of examples of what are deemed non-stayers in the Epsom Classics.
In terms of what we are looking for in the mechanics of a Derby contender in terms of a mid-race minimum stride frequency, the average that the last 11 Derby winners have bottomed out at in the middle section of the race is 2.11sps (strides-per-second). At the extreme ends of those averages were the 2.18sps of Anthony Van Dyck and the 1.99sps registered by Adayar.
Typically, analysis of the runners for the Derby might throw up a couple of red flags signifying mechanics that are likely to be unsuited to the test of the race, but this year we are confronted with an unusual case whereby three of the front four in the market have significant concerns attached to them.
The Aidan O’Brien-trained Delacroix is the favourite for the Derby, but striding analysis places a significant red flag of concern next to him with regard to his stamina. He is a son of Dubawi whose progeny are well established as being particularly fast striders for how far they stay. Indeed, when assessing the likely best trip for progeny of Dubawi, wider analysis suggests that upwardly adjusting the stride-based distance assessment by 21% to account for this is appropriate. However, Delacroix is such a fast strider that even with the Dubawi adjustment, he still rates as a doubtful stayer in the Derby.
His two wins in Derby trials over 10f this season have come in steadily-run races that haven’t examined stamina, particularly his latest start in the Cashel Palace Hotel Derby Trial Stakes which had a finishing speed percentage of a remarkably high 115.3%. The main concern about Delacroix is that we have seen plenty of him with him having had seven starts in his career, but he has never managed to get his mid-race minimum stride frequency below 2.23sps. Indeed, in most of his races his minimum bottomed out a fair bit higher than that, with his average mid-race minimum stride frequency in his other six starts being 2.28sps. These numbers sit a long way outside that of the typical Derby winner and even well outside that of the faster-striding Derby winners of recent years.
Now, pedigree enthusiasts might point out that Delacroix’s half-sister Grateful (by Galileo) won a Group 1 over 14f as evidence in support of the case for him to stay a mile-and-a-half. However, she was a very different filly to what he is in mechanical terms, as she was a much slower strider that was able to drop her revs to as low as 2.12sps in her races.
Personally, I have a very high regard for Delacroix and expect him to win Group 1s this season, but whatever happens here I suspect he will prove to be more effective back over shorter trips.
The Lion In Winter is a more difficult one to assess as we have only seen him three times, so the volume of data we have on him is lower. However, based on what we have seen, a red flag has to be placed beside his potential stamina for the Derby too. His mid-race minimum stride frequency of 2.26 is well out of line with the typical Derby profile and while progeny of his sire Sea The Stars get a projected trip adjustment of +15%, that isn’t nearly enough to take him out of red flag territory. That we have seen so much less of him demands more leeway for consideration that he might show us a different side to his mechanics in the Derby that will give him a better chance of getting the trip. However, as promising as he is, based on what we have seen so far it looks much more likely that he will be more effective at shorter trips than a mile-and-a-half.
The Charlie Appleby-trained Ruling Court has been seen a little bit more on the track with four runs and a victory in the 2000 Guineas to his name, but he is also the one making the biggest step up in trip from a mile to this mile-and-a-half distance. This much different test will need to bring about a change of a very unusual extent in his mechanical output if he is to be seen to best effect over it, as his mid-race minimum stride frequency of 2.27 in his last three starts is the highest of all the three red flaggers. This raises substantial concerns about his ability to be fully effective in the Derby.
Essentially, if Delacroix, The Lion In Winter or Ruling Court stride in a similar style to what they have in their careers to date and still go on to win the Derby, they will go into the analytical history books as the biggest mechanical outlier amongst all recent Derby winners.
Of course, every rule tends to be get busted at some point and the likes of this analysis is no different. While a striding outlier hasn’t won the Derby in recent times, it will happen again at some point. The circumstances where we tend to see outliers prevail are either an exceptional horse overcoming their unsuitability to the test via sheer class or a below-standard renewal of the race that doesn’t require as high a level of performance as normal to win it.
With so many of the main contenders for this year’s Derby not fitting the typical mechanical profile of a Derby winner, perhaps this is the year that will produce an exception to the rule. However, my inclination is very much to play the percentages and oppose Delacroix, Ruling Court and The Lion In Winter. At the time of writing, that trio account for about 65% of the betting market, so I’m odds-on to have egg on my face by 15:33 on Saturday afternoon!
On the other side of this analytical coin, a selection of those that fit the mechanical profile of a typical Derby winner are Pride Of Arras, Lambourn (likely to stay even further than a mile-and-a-half), Stanhope Gardens, Midak and Tennessee Stud who should all have no issues with the trip and test.
Get the eggs ready, I can’t wait to watch it unfold.
