The Hidden Harm:  Why Lunging Horses with Side Reins Causes Lasting Damage

Introduction: Rethinking Tradition in Horse Training

For decades, lunging with side reins has been taught as a “fundamental” exercise in horse training. Many riders and trainers still believe side reins encourage a horse to "accept the bit" or "develop a better topline." On the surface, it may look like the horse is working “round,” but the truth behind this image is far more complex — and often, deeply damaging.

This isn’t about blame. Many horse owners use side reins because that’s what they were taught, and they genuinely want to help their horses. However, as our understanding of equine biomechanics, psychology and emotional wellbeing grows, it’s time to question old methods and embrace more ethical, sustainable training systems.

Let’s explore why lunging horses with side reins can cause irreversible harm — physically, mentally and emotionally — and how correct posture and natural movement training can achieve what force never can.

The Problem with Force: Why Restriction Isn’t a Training System

Force, in any form, is not a training method — it’s a shortcut that compromises the horse’s physical and emotional health. When side reins are attached during lunging, they restrict the horse’s head and neck movement, forcing an artificial frame that mimics collection but lacks the correct muscular engagement underneath.

True collection and self-carriage cannot be forced. They are the result of systematic, patient training that teaches the horse to balance laterally (side to side) and longitudinally (front to back). When side reins fix the head in place, the horse cannot use its neck for balance — an essential function of the neck in locomotion.

The result is tension, imbalance and compensation throughout the body. What looks like progress from the outside is often the early stage of biomechanical breakdown.

The Biomechanical Reality:

What Happens Inside the Body

A horse’s movement is a symphony of co-ordination — the spine, pelvis, neck and limbs all work together to maintain balance and forward motion. When side reins interfere with that balance, the entire system begins to fail.

1. Neck and Spine Restriction

The horse’s neck acts as a counterbalance for every stride. When fixed by side reins, the horse loses the ability to stretch, telescope and adjust naturally. This restriction leads to compression of the cervical vertebrae, tension in the nuchal ligament, and eventual discomfort or arthritis in the neck and poll area.

2. Hollowing of the Back

Because the horse cannot lift its back without a free neck, lunging in side reins encourages hollowing through the thoracic spine. Instead of engaging the core muscles to support the back, the horse braces against the pressure, dropping the sternum and disengaging the hindquarters. Over time, this posture can cause muscular atrophy and saddle fit issues, as the back loses its natural elasticity.

3. Pelvic Misalignment and Loss of Power

True engagement comes from the hind end — the flexion of the lumbosacral joint and the rotation of the pelvis. However, when the front end is fixed, the hind legs can’t reach under properly. The horse begins to trail behind, pushing rather than carrying itself. This creates uneven loading on the joints, leading to hock and stifle strain and possibly tendon injuries.

4. Disrupted Breathing and Balance

The restriction of the neck and jaw also interferes with airway function. A tight poll and throatlatch reduce the ability to breathe freely, which further stresses the body. In the long term, this can contribute to reduced stamina, stress responses and tension-related behaviors such as teeth grinding, head shaking and resistance.

The physical picture may look “neat” from the outside — a horse moving with a rounded frame — but internally, it’s a system in distress.

The Mental and Emotional Cost: A Silent Suffering

Horses are not machines; they are sentient beings who experience stress, fear and confusion. The use of side reins often teaches horses to submit through discomfort rather than understand through communication.

1. Learned Helplessness

When a horse feels constant pressure on its mouth or poll and cannot find release, it eventually gives up. This state is called learned helplessness — a psychological shutdown where the horse stops offering responses because nothing it does brings relief. From the outside, the horse looks "calm" or "obedient," but inside, it has emotionally disconnected.

2. Loss of Curiosity and Confidence

Training should build a horse’s curiosity and confidence. However, force-based methods make horses wary of movement and contact. Over time, these horses lose the natural spark and willingness to engage. The "dead mouth" or "lazy attitude" some trainers complain about is often the direct result of over-restriction.

3. Erosion of Trust

The relationship between horse and human depends on trust — the belief that the human will not cause pain or confusion. When a horse is consistently worked in discomfort, that trust erodes. Even if the trainer later switches to softer methods, the emotional damage can linger for years.

Correct Posture:

The Key to True Balance and Self-Carriage

When a horse is trained to move systematically and naturally, there is no need for artificial aids like side reins. Correct posture and balance create the very qualities riders desire — roundness, engagement, elasticity and connection — without coercion.

1. Lateral and Longitudinal Balance

Teaching a horse to carry itself laterally (through bending and straightness exercises) and longitudinally (through transitions and tempo control) builds coordination and strength. The horse learns to find its own balance, rather than being held in a frame.

2. Telescoping of the Neck

A truly balanced horse will begin to telescope its neck — stretching forward and outward with relaxation. This natural movement releases the topline and allows the back to lift, creating the foundation for a healthy, engaged stride.

3. Core Engagement

With the back lifted, the abdominal and psoas muscles activate, stabilizing the spine. This core engagement supports the rider’s weight in ridden work and prevents back pain. No artificial restraint can replicate this internal muscular harmony.

4. Pelvic Flexion and Hindquarter Power

As the horse’s posture improves, the pelvis naturally begins to flex. This allows for flexion in the lumbosacral joint — the gateway to true collection. The horse begins to carry weight on the hind legs rather than pulling from the front, creating power without tension.

Why Side Reins Can’t Teach Balance

Side reins create the illusion of balance, not the reality. They hold the head down, but they do not educate the body. A horse that is forced into a frame may appear to “work through the back,” but in truth, the key muscles are disengaged.

Real balance develops when the horse learns to coordinate movement independently. This can be achieved through thoughtful groundwork, lunging with correct posture education, in-hand work, and progressive ridden training that builds strength and understanding step by step.

The goal is for the horse to carry itself, not to be carried by equipment.

The Irreversible Consequences of Artificial Aids

Many horses that have been trained in restrictive equipment show long-term damage — both visible and invisible. Muscular asymmetry, chronic tension, joint wear and emotional dullness are common outcomes. Once a horse’s trust or body has been compromised, rehabilitation is possible but often slow and incomplete.

Some horses never recover their natural elasticity or confidence. This is why it’s so important to educate early and prevent harm, rather than repair it later.

A Kinder Alternative:

Teaching Through Understanding

Building a horse that moves with grace, confidence and power doesn’t require force — it requires patience, observation, and consistency. Training through understanding means recognizing each horse’s unique conformation, mental state and learning pace.

When we focus on helping the horse find balance rather than enforcing a shape, we unlock their true potential. This approach develops not only stronger muscles but also a deeper emotional connection.

Practical ways to encourage correct self-carriage:

• Begin every session with in-hand work to activate posture before movement.

• Use re-balancing to develop longitudinal balance.

• Encourage neck extension to release the topline.

• Practice lateral exercises like shoulder-in and haunches-in to improve suppleness.

• Reward every effort toward relaxation and balance — the horse learns through comfort, not coercion.

• Over time, this method creates a horse that moves beautifully out of choice, not fear.

Conclusion: From Control to Connection

Lunging horses with side reins is a practice rooted in outdated thinking — one that values appearance over wellbeing. The physical, mental, and emotional costs are too high and modern equine science now gives us better ways.

“When we replace restriction with understanding, force with feel and control with connection, we don’t just train better horses — we create partners who move with joy, strength and trust.”

True horsemanship is not about making a horse do what we want; it’s about helping them become what they were designed to be —

balanced, expressive and free.

**With the correct training, your horse can look like this WITHOUT the use of side reins!!!**