I feel really heartened by how many of my clients want to embrace a way of training that is based on equine biomechanics but saddened when I hear that someone has opted for the quick fix and lunged their horse in side reins. Side-reins are single straps which attach from bit to girth (or surcingle) and, so their fans claim, will help the horse to flex and achieve a proper outline, encourage straightness and softness and engage the hindquarters to promote balanced, forward movement during training. Right? Wrong!
Just because you pin your horse's head into a vertical position does not mean your horse is flexing throughout his whole body or in a 'correct outline' but unfortunately when i ask many of my new clients what the perfect outline should be, they firstly (and usually only) say 'the head will be on the vertical.' The use of side-reins highlights this popular misconception and the way many people train horses; focusing purely on the front end. I'm sure if you flick through your social media right now, you will see many horses whose heads are beautifully set on the vertical, but if you take a closer look, you'll also see that they have very small hind ends with very little muscle.
The head flexing at the poll toward a more vertical position with an arched neck should occur as a bi-product of the horse shifting his weight onto the hind end. He needs to longitudinally rotate his pelvis whilst at same time flexing his back legs so they step underneath his body which allows the wither to lift, lightening the front end. So, in order to get a biomechanically correct outline, we need to ask the horse to take more weight on the hindquarters to improve the front end, not go straight to the front of the horse and work backwards. And for a horse to learn how to balance himself and use his muscles correctly TAKES TIME!
Even though this is a fit and good looking horse there is still evidence of the negative consequences of using side reins. Note how the horse is leaning on the side reins and hollowing the back causing the saddle to lift up. The muscles on the underside of the neck are overused and tense. A flash noseband is needed to stop the horse opening his mouth and fighting the restraint of the side reins and revealing lack of true balance.
The horse's head and neck are very heavy and therefore the positioning of this part of the body is integral to the overall balance of the whole horse and as a horse works and develops he needs to be able to adjust his neck position. If instead, you use side reins that pin the horse's head and neck in a rigid fixed position, (and elastic inserts aren't any better!) his body which isn't developed enough to carry his head and neck like this naturally will find a way to evade them in ways that many people won't even notice when lunging. For example he may twist his neck and back, drop the base of his neck and back and do no end of distortions to protect his weaker muscles. The one definite outcome of side-reins is that they will force the majority of the horse's weight to be carried on the forelegs, creating the opposite of what most riders are after, a horse that is on it's forehand. Most horses will also become even heavier in the riders hands if they have leant to evade their weaker muscles by leaning on the bit or they will have opted to curl behind the bit so that you can't get a true contact at all. This latter problem is one that is very hard to correct.
Not only will a horse that is pushed onto his forehand this way be more difficult to ride, with a short, choppy stride and likely to trip, he is destined for front end lameness as well. Also, because the horse is often really driven forward so that to the untrained eye the back legs look like they are engaged (see photo above), because the pelvis isn't rotating properly, the back will protect itself by becoming stiff, which means you won't be able to achieve true collection or a good bascule over fences. But, far worse, if the hind legs aren't swinging under coupled with rotation of the pelvis, you could be sending your horse down the slippery slope towards kissing spine, SI injury and stifle problems.
So, whichever end you look at it, side-reins aren't good for your horse!
Side reins don't allow for any stretch, block suppleness and definitely don't encourage a horse to move biomechanically correctly. They also give no relief or release to the horse who is simply trying to work out what is being asked of him. This quick fix outcome will only be an unhappy horse and ultimately an unhappy owner.
My advice to any client thinking of using side reins is very clear 'PLEASE DON'T!' The key to good training is to focus firstly on the hind end and when you have the hind end working correctly, the front end will naturally fall into place. I'm a big fan of pole work as a very effective, non invasive schooling technique suitable for all ages and abilities that gets you and your horse to engage in both body and mind. It can be fun too!
Unfortunately, like most things in life, there are no quick fixes. Time, patience and a happy horse is by far the most successful route.