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Discussion on Exercise distance and speed affect the risk of fracture
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Moderator:
DrO
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Posted on Sunday, Sep 10, 2006 - 1:32 pm:
Though we have long known that racehorses in training have greatly increased risk of fracture as their exercise level is increased we also know that increased level of exercise has to take place to strengthen the skeletal system. This summary provides some specific guidelines on this issue.
DrO
Bone. 2006 Aug 19;
Exercise distance and speed affect the risk of fracture in racehorses.
Verheyen K, Price J, Lanyon L, Wood J.
Epidemiology Unit, Animal Health Trust, Newmarket, United Kingdom.
In order to gain insight into those training regimens that can minimise the risk of fracture in athletic populations, we conducted a large epidemiological study in racehorses. Thoroughbred racehorses provide a suitable model for studying fracture development and exercise-related risk factors in physically active populations. They represent a homogeneous population, undertaking intensive exercise programmes that are sufficiently heterogeneous to determine those factors that influence injury risk. Daily exercise information was recorded for a cohort of 1178 thoroughbreds that were monitored for up to 2 years. A total of 148 exercise-induced fractures occurred in the study population. Results from a nested case-control study showed a strong interactive effect of exercise distances at different speeds on fracture risk. Horses that exceeded 44 km at canter (less than 14 m per s) and 6 km at gallop (greater than 14 m per s) in a 30-day period were at particularly increased risk of fracture. These distances equate to ca. 7700 bone loading cycles at canter and 880 loading cycles at gallop. Fifty-six fractures occurred in the subset of study horses that were followed since entering training as yearlings, when skeletally immature (n=335). Cohort analysis of this data set showed that, in previously untrained bones, accumulation of canter exercise increased the risk of fracture (P</=0.01), whereas accumulation of high-speed gallop exercise had a protective effect (P<0.01). However, increasing distances at canter and gallop in short time periods (up to one month) were associated with an increasing fracture risk. All training exercise involves a balance between the risk of fracture inherent in exposure to loading and the beneficial effect that loading has by stimulating bone cells to produce a more robust architecture. Results from our study provide important epidemiological evidence of the effects of physical exercise on bone adaptation and injury risk and can be used to inform the design of safer exercise regimens in physically active populations.
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Member:
Erika
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Posted on Monday, Sep 11, 2006 - 7:18 am:
Wow, I find it interesting that cantering increased the risk more than the galloping. I would have thought it the opposite.
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Member:
Christos
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Posted on Monday, Sep 11, 2006 - 5:01 pm:
Do they mean 44 km canter and 6 km gallop accumulated within 30 days ? On an 18 mo baby?
Shouldn't this be under the horse slaughter discussion?
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Member:
Erika
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Posted on Monday, Sep 11, 2006 - 6:19 pm:
Good one, Christos. Sad but true.
Erika
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Member:
Christos
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Posted on Monday, Sep 11, 2006 - 11:47 pm:
Impressive study, you can download it here:
https://www.vetschools.co.uk/EpiVetNet/epidivision/Verheyen/files/Thesis%20Final% 20small.pdf
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Moderator:
DrO
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Posted on Tuesday, Sep 12, 2006 - 7:26 am:
You misunderstand what they say Erika: they are not talking about canter work causing fracture but that the accumulation of canter work increased the chances of a fracture, I would guess during gallop. In other words as horses accumulated increasing amounts of canter work there was an increased propensity of fracture.
Christos I do think they mean the horses did both and this likely represents a population of horses whose bones were not allowed enough remodeling time following gallop work. Super link. Studying the two proposed training schedules it is incredible how introducing a bit of gallop earlier, while creating a slight increase of earlier breakdown, later on halves the rate of breakdown.
DrO
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Member:
Erika
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Posted on Tuesday, Sep 12, 2006 - 8:08 am:
Dr. O, I guess my wording was wrong, I understood the accumulation factor, but I didn't know cantering would be sufficient stress to increase fracture risk.
I wonder how these studies would relate to horses in other demanding sports like eventing or field hunting? I've known a few horses to have broken legs in the hunt field. With our tendency to start horses later, are the horses then left with a lifetime increased risk? Or can bones be strengthened just as well at any age?
Thanks for the clarification.
Erika
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Moderator:
DrO
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Posted on Wednesday, Sep 13, 2006 - 6:39 am:
There are both specific and general conclusions to this work. Some of the general conclusions are important to all sports. For instance if I increase the work load on my horse how long does it take the skeletal system to adapt to this change.
I don't think the bones, which remains very adaptable throughout life, are as much risk as the tendons, ligaments, and cartilage which are very poorly adaptable once the horse matures. We still do not have clear ideas of what are optimal work loads for the growing horse that would maximize later soundness.
DrO
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