That Chandelier Moment

June 9, 2022

Even as a pig-tailed, freckly-faced Pony Clubber, I wanted to know why. Why did my friends’ ponies score more highly than mine when competing in eventing? The sport of eventing, or horse trials, is made up of three phases. First comes dressage (“horse dancing”), which judges how well you perform a set pattern of movements, rather like ice skating. This is followed by two jumping phases, where penalties are added if you fail to jump the obstacle. I fully understood assessment of the jumping phases was easy to understand – the horse either jumped the fence or not – but dressage remained a mystery. What was it about Monica and Binky’s way of going that was so much more pleasing to the judge than my own efforts with Cocoa? This niggled at me for many years, especially as asking dressage judges only resulted in cryptic responses: “We’re looking for elasticity, suppleness and energy”. Fine, but what did this mean in practical terms? What aspect of Binky’s gait made it more “elastic” and “energetic” than Cocoa’s?

In 2000, I began a degree in Equine Science at Imperial College (Wye) where I finally had a chance to get some answers. I would sit for hours in the library reading as many papers on movement as I could get my (often literally) mucky hands on. One day, I found an article published a few years earlier. The moment I read the title, “Biokinematic differences between riding horses judged as good and poor at the trot”, I knew I had the answer to my dressage dilemma: it wasn’t so much a lightbulb switching on as a chandelier-full.

Here, finally, were measurements. Quantification. In the paper, the authors compared the movement of two groups of horses: one given high scores (Group I) and the other given low scores (Group II). The main results were that Group I horses took longer, slower strides than Group II, and the joints of their hind limbs flexed more when bearing weight. Even more excitingly, the discussion section interpreted these results in terms of judge-speak, particularly “energy, elasticity and propulsion”. Bingo! Two of the buzzwords that had mystified me ten years ago, right there in an academic paper. The article explained that these judging criteria were linked to the flexion of the limb joints, and therefore to the degree of elastic energy stored when the joints were flexed.

It made sense. When a horse’s hoof hits the floor, the joints flex – particularly those of the lower limb. The elastic structures that wrap around and support the joints (primarily two flexor tendons and a ligament) stretch and store elastic potential energy, rather like an elastic band. As the hoof starts to leave the ground, they begin to recoil. During recoil, the stored energy is returned as kinetic, or moving, energy and helps to drive the limb forward and upward. The more the joints flex, the greater the stretch and the larger the amount of potential energy stored. Just as a highly-stretched rubber band has more ping when you release it, a highly-stretched tendon will also return more energy. Consequently, the horse’s limb is propelled forward and up with greater energy, which would be interpreted by the judge as a more elastic gait. What I’d learnt is that use of the term “elasticity” wasn’t as arbitrary as I’d thought; it is linked in a very real way to the elastic properties of the supporting structures. In turn, the degree of stretch is closely linked to joint flexion – one of the criteria identified by the judges in the horses given a high score.

The implication was that results made sense of a subjective measurement – quantifying the quality of the gait. A judgement explained and corroborated by science.

The pig-tailed nine year-old wasn’t wrong to want to know why, because wanting to know why (and what, and when) is what drives science. Asking and trying to answer questions is the backbone of the whole discipline – even if you have to wait ten years to find the answer. Or, in my case, find the light switch.

Pauline Addis – Editor, Oxford Science Editing

Photo by Grossick Photography www.grossick.co.uk