To Boot or not to boot?

To Boot Or Not To Boot?

Hot Legs and Investigating Weighted Boots for Rehab

By Kallista Charles 

BSc (Hons) Veterinary Physiotherapy Student

"Jump higher, gallop faster and increase collection"…demands within the equestrian sport are ever increasing (Back and Clayton, 2001). As athletic boundaries are pushed to their limit, maintaining quality movement and preventing injury is becoming an ever difficult balance to achieve. Different disciplines predispose horses to different injuries due to varied loading on anatomical structures. Yet a common theme of injury involves the ligamentous and tendinous region of the lower limb. With the superficial digital flexor tendon being injured six times more frequently in elite event horses than non-elite horses, protection using exercise boots is the most common preventative measure (Veterinary News, 2014). The incorporation of exercise boots into tack rooms across the globe is normal practice with negatives and contraindications of their use rarely considered. With the recent re-emergence of concerns regarding booting and overheating tendons – also known as exercise-induced hyperthermia - through applying boots and bandages, should the equestrian world question their true functionality? And do weighted boots hold a place in training and rehabilitation programmes?

Boots and Bandages: The Modern Dilemma

Originally, bandages were used for covering wounds and rehabilitation purposes. Their use in exercise has developed from this; as the awareness of incorporating prehabilitation (management practices to prevent injury from occurring) into equestrian disciplines is essential for long term competitive success. Bandages and exercise boots function to protect from impact and support anatomical structures by reducing fetlock extension (Westermann et al., 2014). With 70% of racehorses suffering from tendon injuries failing to return to previous levels of performance (Solheim et al., 2017), leaving the exposed tendon structures of the lower limb without protection seems unwise. But what are the negatives of applying exercise boots and bandages for exercise?

The interrelationship between the high incidence of injuries to the superficial digital flexor tendon and overheating caused by exercise boots is one not to ignore (Waterlane Equine Vets, 2018). Whilst core tendon temperature remains relatively constant at rest (approximately 37.8℃), temperature increases significantly during exercise. Reaching  approximately 43.3℃ during high intensity exercise, this can be enough to cause tendon cell death even without boots and bandages applied (Westermann et al., 2014). It can be argued that damage to tendinous tissue occurs chronically through overheating during and after exercise, rather than an acute injury.  This is because tendons have poor vasculature, meaning that blood supply towards and away from tendons is limited. This means that heat accumulates in the tendon and reduces post-injury healing ability. Whilst boots and bandages may aim to protect the limb from impact, they also insulate the limb, thus preventing effective heat loss expelled by the tendons during exercise. But how do boots and bandages compare? 

Westermann et al. (2014) completed a study comparing the effect of both bandages and tendon boots on skin temperature at rest and after exercise. The findings concluded that there was a significant increase in skin temperature and most noticeable with bandage application. Conclusively, bandages have the potential to increase skin - and consequently, tendon temperature - more so than boots. This may be because of the availability of more advanced perforated and ventilated exercise boots on the equestrian market acclaimed to be of more superior boot design. On the other hand, studies have found that perforated boots demonstrated higher heat emissions in comparison to traditional, non-perforated boots. (Hopegood et al., 2013). However, the research is limited to surface temperature. For such research to be valid, further investigation on the relationship between core tendon temperature and skin surface temperature is required to determine whether ventilated equipment is truly a more beneficial alternative.

The Use of Weighted Boots in Rehabilitation and Training

Weighted boots can be defined as a training aid that aims to accentuate the flexion and extension of joints during movement, thus increasing stride expression. Curiosity surrounding weighted boot application on horses originates from its initial use in human medicine - when applying a 2kg mass to the lower leg of a human resulted in increased hip flexion and knee extension (Noble and Prentice, 2006). 

In 2009, Murphy conducted a similar study on showjumpers and found there to be significant increase in hock height and thus hindlimb elevation over jumps when adding weighted boots. Due to the apparent effect of proprioception in this initial trial, findings from this study indicate how weighted boot application could have a place in training in addition to rehabilitation. Investigation into the theory behind weighted boot effectiveness is in its early stages and inspired me to conduct a small research project in conjunction with my Veterinary Physiotherapy degree. 

The research project compared the effect of weighted boots (at 250g, 500g and 750g) on equine stride kinematics. Fluorescent anatomical markers were placed onto the joints of the forelimb and hindlimb. 16 horses were used in the experiment and were each walked and trotted in front of a video camera on a hard surface wearing weights of 0g up to 750g. The walk and trot up was recorded three times for each horse to generate an average value and thus eliminate inaccurate data to increase the reliability of the study. Video recordings were then processed through Kinovea, a software which enables kinematic analysis of data. The maximum flexion and extension of each joint was measured in addition to stride length. Any differences found in stride kinematics were analysed by statistical tests to determine whether they were significant or not. Results of this investigation highlighted four key findings:

1. 250g weights consistently and significantly decreased flexion and increased extension of joints. 750g weights had a similar effect but not as significantly as 250g weights.

2. 500g weights were commonly associated with a counterintuitive effect on joint movement; either decreasing extension or increasing flexion in comparison to 250g weights. 

3. Proximal limb joints were more affected by weighted boot application than distal limb joints.

4. Forelimb joints were more affected than hindlimb joints.

Whilst the benefits of weighted boots have been experienced through this personal experiment, it is important to acknowledge there is limited research into the advantages and limitations of weighted boots (Rumpler et al., 2010). Additionally, this experiment was conducted during walk and trot on a hard surface; there are many additional factors that could influence their effect. The influence that weighted boots have on joint range of motion prompts questioning into whether such effectiveness results from physics (the trebuchet apparatus theory) or biology (the proprioceptive response). Proprioception can be defined as the communication of sensory neurones to the central nervous system to produce a sense of bodily awareness (Jones, 2015). On the other hand, weighted boots act as a counterweight to the balance of the trebuchet apparatus. This means that potential energy generated by the weighted boots in motion is converted into elastic potential, resulting in projectile forces.

The benefits of weighted boots are not simply exclusive to the limbs; they can also increase the flexion and extension of the lumbar back (Wennerstrand et al., 2006), highlighting how equipment can interlink and synchronise with one of the most essential systems in physiotherapy: the equine musculoskeletal system. The biological effects of weighted boots highlights their potential ability to provide benefits to physiotherapy. For example, increased joint range of motion leads to increased muscle activity, a desirable feature in movement. However, for progression in this area of research, potential ethical concerns related to weighted boot application require assessment to determine their full effect.  

The incorporation of weighted boots into rehabilitative exercise prescription plans can be useful for re-educating gait patterns, enhancing muscle activity through increased joint motion and proprioceptive awareness. In turn, this can provide beneficial outcomes for muscular strength and enhanced neuromuscular response for both a horse in rehabilitation or competitive training. Weighted boots are most effective when applied for a short duration of time as the horse can become habituated to (accustomed to the feeling of) the additional mass of the boots, reducing the influence the boots have on stride dynamics. The greatest increase in joint range of motion is noticed post-weight application, albeit fleeting. This emphasises the importance of only applying weighted boots for short and thus effective lengths of time and should only commence following the advice of a veterinary or equestrian professional to determine if this would be the correct tool for your horse.

In all, there still remains a strong discussion into  both  the best way to  protect legs while combating overheating tendons and the measurable effects of weighted boots in different scenarios. However, the underlying fundamental principle that connects matters surrounding tendon and musculoskeletal health is that concern for equine care is increasing in both scientific research and horse ownership. Although further research is most definitely required, the fact that booting has been a hot topic over recent weeks shows continual interest and commitment to improve equine welfare.

At Trackener we are committed to helping owners prevent horse health issues and injuries while achieving the best performance. We would love to hear your thoughts on this subject: do you have any tips to prevent limb problems? Have you had positive or negative experiences with boots and bandages for exercising? Have you had any experience using weighted boots? Let us know!

About the Author

Having ridden competitively for 18 years and trained with international dressage riders, Calli was inspired by the bio mechanics behind her training and wanted to learn more about how she could help the animals that she adored. Qualified in Kinesiology Taping and undergoing her BSc (Hons) Veterinary Physiotherapy degree at Moreton Morrell Equine College, she will soon be a qualified veterinary physio. To follow her diary in the life of a vet physio student, you can visit her instagram and facebook pages.

References

Back, W. and Clayton, H. (2001) Equine Locomotion, Elsevier Health Sciences.

Hopegood, L., Sander, L., Ellis, A. (2013) The influence of boot design on exercise associated surface temperature of tendons in horses, Comparative Exercise Physiology, 9 (3-4), pp. 147-152.

Jones, J. (2015) The Power of Proprioception, Equus, 449, pp. 34-37

Murphy, J. (2009) Weighted boots influence performance in show-jumping horses, The Veterinary Journal, 181 (1), pp. 74-76.

Noble, J. and Prentice, S. (2006) Adaptation to unilateral change in lower limb mechanical properties during human walking, Experimental Brain Research, 169 (4), pp. 482-495.

Rumpler, B., Riha, A., Kotschwar, A., Licka, T., and Peham, C. (2010) Influence of shoes with different weights on the motion of the limbs in Icelandic horses during toelt at different speeds, Equine Veterinary Journal, 42 (38), pp. 451-454.

Solheim, T., Tarabova, L., Faixova, Z. (2017) Changes in temperature of the Equine skin surface under boots after exercise, Folia Veterinaria, 61 (4), pp. 17-21.

Veterinary News (2014) Predisposed to injury: difference sports carry different risks for horses (online). Available from <http://veterinarynews.dvm360.com/predisposed-injury>. 

Waterlane Equine Vets (2018) Bandages, boots and tendon damage (online). Available from <http://www.waterlaneequinevets.co.uk/wp-content/uploads/2017/03/Thermoregulation-Polo-Times-article.pdf>.

Wennerstrand, J., Johnston, C., Rhodin, M., Roethlisberger-Holm, K., Drevemo, S. (2006) The effect of weighted boots on the movement of the back in the asymptomatic riding horse, Equine and Comparative Exercise Physiology, 3 (1), pp. 13-18.

Westermann, S., Windsteig, V., Schramel, J., Peham, C. (2014) Effect of a bandage or tendon boot on skin temperature of the metacarpus at rest and after exercise in horses, American Journal of Veterinary Research, 75 (4), pp. 375-379.