Forces in Flight - The biomechanics of jumping
Article by Laura Steley
Jumping is a skill which, although innate, can be hugely demanding and takes considerable practice in order for horses to successfully tackle the fences seen in today’s steeplechase, cross country and hurdle races. We all know some horses are “natural jumpers”, and seem to find the job easy, others may require more refinement, either way the anatomical chain of events which need to happen are the same for every horse, regardless of jumping sphere.
Biomechanics is the scientific study of the movement of a living body, in this case a racehorse, looking at how muscles, bones, tendons and ligaments all work in sync to produce a specific movement. Analysing and interpreting how our racehorses look and move (static and dynamic evaluation) is a skill which many horse people have developed and perfected over countless years within the industry, but it can be subjective. A biomechanical understanding can only be a rewarding and beneficial practice from both a welfare and results point of view. This type of in-depth evaluation is only possible due to high-speed cameras and expert gait analysis technology; it would be inconceivable to take in all the different movements needed via the naked eye, since one jumping effort is over in all but a second!
As the jump racing season begins to ramp up in the UK and Ireland, and the rest of Europe is still going strong, the importance of schooling remains. For trainers, developing horses that are not only bold and willing but also biomechanically efficient over fences is one of the keys to consistent, injury-free performance. While traditional training methods hold strong, recent advances in equine biomechanics are providing fresh insights into how different schooling approaches affect the horse’s body, stride, and ultimately, their jumping success.
The jump can be broken down into five clear phases, all with equal importance with the necessity to be coordinated in order to produce a careful and fluent jump. Of course, jockeys and riders will and can have an influence on all phases, but this is not something we will touch on; for this article let us assume the rider is in complete synchronisation with the horse, allowing all phases to be carried out as nature intended.
Approach
An often-overlooked component, the approach to a fence will have a profound effect on the quality of the jump, its function being to generate suitable conditions for take off. On the approach to a fence the horse needs to be in a well-balanced, rhythmic and forward-thinking stride. Obviously, we are looking at steeplechasers and hurdlers, therefore horses will be approaching in gallop, meaning strides will not be as easily adjusted and the horse will need the ability to judge and correct themselves as necessary. As a general rule, the faster the approach, the more strength and skill needed to tackle the fence efficiently.
The horse will need to be able to adjust their head carriage to see and judge the fence sufficiently, a high head position or restriction of the head and/or neck will inhibit this. In the final stride before the next phase (take off), the horse will reach forward and down with their neck, thus lowering their centre of gravity. This will produce a sudden braking action, stopping forward momentum for a brief moment, which will engage the hindlimbs under the horse’s body, allowing them to obtain the maximum amount of push from the hindquarters and producing enough energy for take off.
Maximum jumping capacity is entirely determined by the impulsion at take off, which in turn is a compromise between approach speed (which reduces the time for energy production) and muscle strength (which limits the magnitude of energy generated). Impulsion is defined as stored energy by engagement, achieved through controlled muscular power in the hindquarters, enabling increased hindlimb protraction and joint compression/flexion. There are many factors which can affect a horse’s approach, especially in a racing scenario where competitors can interfere and hinder each other, but in a perfect scenario an approach as outlined above will produce an idyllic take off position.
Take Off
As the final stride is completed the horse’s weight is distributed backwards via the lifting of the head, shortening of the neck and lifting of the shoulders. This shortening of the neck also contributes to the halting of the forward momentum needed to gather energy, as discussed in the approach section.
The non-leading hind leg (the first beat of gallop) is the first to land at the base of the fence. Due to the horse’s weight being pushed backwards, the swing phase of the leading hind leg will be interrupted, this in turn will cause a shortening of stride, meaning both hind legs land almost symmetrically. If for any reason this process is interrupted or inhibited the horse will take off solely from the leading hind (landing in front of the non-leading hind as it would when taking a normal stride), this will cause the horse to be unbalanced and prohibit the flexion needed to jump the fence sufficiently.
Next, the forelimbs will fold up and in towards the horse’s body due to the upward rotation of the shoulders, thus creating a more streamlined shape. The hindlimbs should now be equally flexed in order to push against the ground and create the necessary propulsion. The amount of flexion required is directly linked to the height of the fence, more flexion equals a longer phase of hesitation, creating more force and a larger jump. The quicker the approach the shorter stance phase achievable, therefore strength, suppleness and agility is of upmost importance in a racing scenario.
The average stance phase for a horse tackling a steeplechase fence will be approximately 0.2 seconds. Along with the hindlimb flexion, there will also be rotation of the pelvis due to the flexion of the sacral and iliac junction in the loins, this is at its most effective when the hip joint is placed vertically above the hoof. With maximum flexion of the hindquarters obtained the horse can begin to extend the hind legs and release the coiled energy, a force which must exceed the horses body weight by 3 – 5 times! A study on show jumpers indicated that maximal vertical force increased by about 0.22 N/kg for every 10 cm increase in fence height—meaning a 550 kg horse needed roughly +360 N extra vertical force at 1.4m compared with 1.1 m (Chateau et al., 2020). The abdominal muscles lift the extended topline, and the shoulders rotate forward and upwards assisting the lifting of the hindlimbs off the ground. This is arguably the most important phase, because it is at this point that the trajectory of the horse's flight is determined, and many studies have rightly focused on the take-off parameters in their research.
Flight
The flight phase begins the moment the hind hooves leave the ground, from here nothing can be done to change the path of the horse’s centre of gravity. In this phase the hindlimbs will reach full extension while the forelimbs are flexed tightly against the horse’s girth area. The height of which the hindlimbs can achieve has already been determined at this point, and it is proportionate to the strength of the coil and the push off from the ground via the hind legs. If the approach and/or take off has been suboptimal the horse may twist their pelvis in order to allow the hindlimbs clearance of the fence, the same principle can be applied if the forelimbs are too low, the horse can move their shoulders sideways to assist, but this is likely to have a detrimental effect on the rest of the sequence.
The neck will extend forward, allowing the horse to stretch over the fence due to the pull on the nuchal and dorsal ligament systems, particularly the supraspinous ligament that runs down the top of the back, this is of increased importance the wider the obstacle, for example ditches. The hindlimbs will tuck up underneath the horse’s body, via flexion at the stifles and lifting in the hocks, and the knees will lift, bringing the forelimbs higher away from the fence and increasing their streamline potential – this position is known as a bascule, a French word meaning “arc in motion”. Some horses naturally produce a bascule shape over fences from the moment they begin their training, often a good sign for future form.
Landing
The purpose of this phase is to absorb the impact of landing, retain impulsion and ensure clearance of hindlimbs. On landing the horse will lift their head and neck upwards as the forelimbs descend to the ground, this will slow the horse’s forward momentum so that the force of impact is reduced. The non-leading forelimb lands first and takes all the weight of the horse and force of landing, research has indicated that the force on the horse’s foot on landing from a 4ft fence is approximately 4000 pounds, which is approximately three times the average thoroughbred’s weight. (Schamhardt et al., 1993).
This creates an intense (albeit short lived) amount of pressure on the joints, muscles, tendons and ligaments of the forelimb, particularly the flexor tendons (deep and superficial) and suspensory ligament. It is understandable that injuries to the superficial digital flexor tendon (SDFT) are one of the most observed injuries in racehorses, in a study of steeplechase horses diagnosed with tendon and ligament injuries sustained during training, 89% occurred in the SDFT (Ely et al., 2009).
When the leading forelimb lands, both legs push against the ground in an upward and backward direction. The horse can essentially choose which leg to land on, many horses will favour a landing leg, this is quite a natural thing for them to do and will not cause any issues, the most important thing is that the horse is balanced and comfortable. The hindquarters rotate underneath the trunk and reach toward the ground as the forehand moves forward and out of the way of the hindquarters. The more relaxed a horse is the better, a tense horse will not allow sufficient shock absorption and they are more likely to injure themselves and/or make a mistake. Similarly, if a horse is tired or lacks impulsion blunders are more readily made.
Get Away
The sole aim here is to produce a smooth transition from landing to the potential approach for the next fence. The horse should be able to resume a balanced gallop stride directly after landing (proportionate with the going), this should seem effortless with no restriction of forward momentum. Recovery will be more difficult and take longer if mistakes have been made, or impulsion is lost. Deep ground or pecking on landing can lead to over-reaching, where the forelimbs fail to move before the hind limbs land.
How can we use this information in our schooling practices?
Attempting to optimise these phases through targeted schooling can help improve energy efficiency, reduce injury risk and increase a racehorse’s confidence. As with everything equine, the “one size fits all approach” is rarely successful. Conformation, environment and behavioural traits will all play pivotal roles, therefore the below mentioned methods will vary greatly on relevance and suitability between horses and trainer preference.
Ground poles which are placed before, after or between fences help regulate stride, improve stride awareness and build confidence and co-ordination. With the use of high-speed video analysis, we can clearly demonstrate that training with strategically placed ground poles significantly improves limb symmetry during the flight phase and reduces variability in take-off distances (Walker et al., 2022).
Take-off markers can encourage consistent correct take off points, which in-turn improves bascule quality/jumping efficiency and decreases injury risk. Horses develop a better eye for a fence by associating distance with effort, allowing for more accurate take-off preparation. This is particularly important in races where decisions are made at high speed, sometimes under fatigue.
Gridwork exercises, such as bounce fences or one to two stride combinations are commonly used to develop coordination and timing. Gridwork encourages horses to adopt a more compact frame, increase flexion in the hock and stifle, and improve spinal articulation. However, overuse of gridwork can lead to a mechanical, overly rehearsed jumping style due to horses becoming reliant on the rhythm imposed by the grid rather than learning to make independent adjustments.
Jumping out of a gallop replicates race conditions but presents different biomechanical challenges. Horses must generate sufficient power from a longer stride and adjust mid-flight without the benefit of a collected approach. It is logical to assume that horses trained regularly at gallop over fences will display more consistent take-off and landing patterns. It is also considered to have a positive effect on limb shock absorption due to stronger muscle recruitment and joint control. Still, if overused or poorly executed, galloping fences can reinforce bad habits and/or exacerbate innate biomechanical issues. Horses may flatten their jump excessively or incorrectly anticipate take-off, thus increasing the risk of stifle or suspensory injuries.
Schooling on hills can offer unique biomechanical benefits. Uphill jumping increases demand on the hindlimbs, promoting hindquarter engagement of the gluteals and semimembranosus muscles crucial for a powerful take-off. Conversely, downhill jumping challenges the horse's balance and encourages better forelimb deceleration control during landing. Research has shown that training on uphill gradients significantly increases activation in the longissimus dorsi and biceps femoris muscles in Thoroughbreds compared to flat-ground training (Takahashi et al., 2014). That said, downhill schooling must be used judiciously. The additional forces placed on the distal limbs and hocks can exacerbate underlying conditions and cause unnecessary strain if used flippantly.
Jump schooling on varied surfaces has numerous benefits from a physiological point of view, such as; increased proprioception, improved muscular recruitment and engagement and quicker recovery post landing. From a psychological standpoint, varying terrain reduces monotony and mental fatigue, thus improving concentration and willingness.
All the above schooling tools and techniques possess different advantages and should be chosen on an individual basis. Improvement of jumping technique and fitness is absolutely achievable; however, the over use or incorrect use of schooling techniques can have the opposite effect. Also, excessive repetition of a single fence type or layout reduces adaptability and may lead to habitual errors. Equally important is recognising signs of fatigue, such as reduced jump height, shortened stride after landing, or repeated take-off errors, and ensuring that technical schooling is balanced with mental freshness to maintain motivation and prevent over-schooling. A balance between repetition to build muscle memory and variation to build decision-making and adaptability is the take-home message.
An increasing range of technologies are now available to assess and monitor equine biomechanics, each offering different levels of precision and practicality for field use. High-speed video analysis remains one of the most accessible tools, enabling frame-by-frame review of gait patterns, joint angles, and jump patterns through readily available smartphone apps or more advanced motion-capture systems. Inertial measurement units (IMUs) and wearable motion sensors provide stride-by-stride data on limb symmetry, stride length, acceleration, and impact forces, often in real-time and during normal ridden work. Surface electromyography (sEMG) is increasingly being applied to measure muscle activation patterns, allowing assessment of back and hind-limb musculature during different exercises.
Effective jump schooling is about more than clearing fences cleanly—it's about developing movement patterns that are efficient, repeatable, and safe under race conditions. Combining traditional horsemanship with scientific insight offers the best of both worlds: a methodical, measurable approach to preparing racehorses that jump well, recover fast, and stay sound through the season and beyond. To conclude, I feel it is important to pay some respect to how resourceful our racehorses are. Often dealing with unfavourable going, interference from fellow competitors and at times unfamiliar courses and fences, they put their heart and soul into their jobs. It is safe to say, biomechanics will always play a vital role, but nothing tops a horse with the will and determination to succeed and a huge heart to match!
