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Muscle Development and Back Profiles

Updated: Jan 31

Part 2

This blog will discuss assessing muscle development, lack of topline versus muscle atrophy and how to take a back profile.

Muscle Development

Once you’ve looked at BCS (Part 1), you can then look at muscle development. This tells you the horse’s habitual way of moving, stage of training and fitness and gives clues as to weaknesses or injuries.

First get an overall impression then look in detail. This can be done by dividing the body into broad muscle group categories: topline (extensors), underline (flexors), forelimb flexors and extensors, hindlimb flexors and extensors, front to back: neck/shoulder and front leg/ barrel and back/ hind quarters, and left to right; Does it appear balanced and is it as you would expect for that age, breed/conformation, sport and training level. Are there muscles that are over developed: forearm and chest (horses that pull, or leg movers)? Is the muscle where you would expect it for the sport; jumpers have large second thighs. Are there muscles that are under-developed; hamstrings, gluteals, quadriceps? Big, young gangly horses or those that have not done any lateral work often look a little hollow or flat through the fore and hindlimb abductor muscles. Is there atrophy of the back muscles under the saddle? Is there symmetry left to right (natural crookedness, protecting an old injury or weakness)? Are the muscle tense, or relaxed? Are the muscle contours smooth or are there divots/muscle tears or fat lumps?

Lack of topline versus muscle atrophy.

What do we mean by topline? Roughly it is the green coloured muscle groups in the picture. These muscles develop through working in a biomechanically correct posture and resistance training through carrying a rider. It occurs as the horses center of mass is shifted more towards the hindlegs, this makes the large muscles in the hind legs work harder so they become more bulky; hypertrophied. It also means the muscles either side of the wither work harder to support the weight of the head and neck, so they become more developed too.

Muscle hypertrophy = when a muscle is repeatedly challenged to work harder it adapts to become stronger by recruiting more muscle fibers, becoming more efficient and becoming bigger. So muscle bulk can be used as an estimate for muscle strength.

Muscle atrophy = a loss of muscle bulk, the muscle becomes smaller, flat or even hollow. This indicates a loss of strength or injury. Pain can also inhibit muscle strength.

This ties into BCS. If the horse is under-weight it will generally lack muscle all over including the topline. If a horse is not in work (in paddock condition) its topline muscles will tend to diminish. A healthy horse will have good fat coverage or condition and fair muscle coverage, but without work they won’t have hypertrophied muscles. A horse that looks bulgy and rounded may be muscly rather than fat for instance a quarter horse barrel racer or warm blood dressage horse. This is why it is important to consider fat and muscle separately when looking at BCS.

If the horse is slim and lacking muscle all over the remedy will involve more feed as well as work to develop muscle. Information on feeding for muscle gain with David Marlin.

If the horse is in good condition, but with an unbalanced distribution of muscle; over developed underline and lacking topline, then the style or method of training should be looked at to improve the horse’s way of going. A muscle gets big by doing work, if the muscles on the underline are big is tells you they are doing more work.

If the horse is in good or slim condition and there is atrophy in a particular muscle group eg. hollow through the saddle area, this clearly suggests a saddle fitting issue +/- training style. The muscles of the back have not been able to bulk up as the poorly fitting saddle compresses the muscles and restricts their blood flow. Remedial saddle fitting is a process that aims to restore the health of the horses back and to gain sufficient body condition and back muscle development before the definitive saddle fit. It may involve many refits, soft cushioning pads which will allow the muscles to grow, in hand exercises, lunging and changes to riding style.

You can visually track muscle bulk by taking photos of your horse over time. You can also measure changes in muscle bulk along the back by taking back profiles.

How to take a back profile

Using a flexible ruler (aka flexi curve, architects ruler, or using a piece of flexible wire) stand your horse up square, with their nostrils level with the point of shoulder. Curve your flexible ruler along your horses spine from the wither back as far as it will reach. Draw this line onto a large piece of paper – this will give you an indication of their posture.

Choose several places along your horses back to measure that you will be able to repeat/ locate reasonably accurately in the future.

* Perhaps the highest part of the wither then measure 10cm back along the spine and do 10cm intervals.

* Or measure from the highest point to behind the scapula (where your saddle would sit) and record how many cm back it is.

* Alternatively you could feel for the last rib, follow it up to your horses spine and measure from there.

* Another option is you can feel for and count the spinous processes and make your measurements at particular number vertebrae T8, 12, 18 …

Generally it is useful to have at least 3 measurements 1 towards the front of where your saddle sits, one in the middle and one towards the back of where your saddle sits. It can also be interesting to take the profile over your horses loins or over the top of the pelvis as this will give you an indication of their gluteal development.

Bend the flexible ruler over your horses back. Trace theses curves onto paper, using different colours and make sure you label them with which measurement point they are from, nearside/offside, and date. You can look to see if your horse is symmetrical left to right. It is not uncommon for there to be a difference in contour behind the shoulder, as horses (like humans) can favour one side and be left or right hoofed.

Write a reminder in your diary/ calendar/ phone of when you are going to repeat the measure, generally a minimum of 4 weeks to see much measurable change. Repeat the procedure above and compare to the first set of profiles. You can roughly overlay them to see if your horse has gained or lost bulk. Or if you want to be more accurate mark the mid point of the curve, then measure down 3cm and 15cm, draw a line at right angles and measure the length of this, compare left to right, and compare the cm from one date to another to see how many mm or cm your horse has changed by.

Any changes need to be interpreted carefully. Is an increase really a gain in muscle or could it be seasonal weight gain? If you use the Henneke BCS as described in Part 1 and the condition score has stayed the same, then you can be reasonably confident your horse has gained muscle.

BCS and muscle condition go hand in hand, so I hope these two articles have given you some guidance to help take your horse from fat to fit, or thin to well-muscled.

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