Beyond the Longissimus Dorsi: Activating the Deep Multifidus Muscles for Core Spinal Stability
You know the feeling on some rides—that elusive, floaty connection where your horse’s back is soft, lifted, and engaged. Then there are the other days, when the back feels stiff, hollow, or disconnected from the hind end. For years, conventional wisdom has told us the answer lies in strengthening the “topline,” focusing almost exclusively on the long, powerful longissimus dorsi muscles that run along either side of the spine.
But what if the key to true spinal stability and self-carriage lies deeper? What if the most influential muscles are the ones you can’t even see?
Recent research points to the critical role of a series of small, deep muscles called the multifidus. These muscles act less like the engine of the back and more like its sophisticated suspension system. Learning how to activate them can transform your horse’s posture from the inside out.
The Big Movers vs. The Deep Stabilizers
To understand the importance of the multifidus, it helps to visualize the horse’s back in two distinct layers.
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The “Mobilizer” Muscles (e.g., Longissimus Dorsi): These are the large, superficial muscles that produce big movements—like extending the back or flexing it side to side. They are the powerhouses, the engines of locomotion. We see them, we feel them, and we spend a great deal of time trying to develop them.
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The “Stabilizer” Muscles (e.g., Multifidus): These small, deep muscles connect individual vertebrae. Their job isn’t to create large movements but to provide segment-by-segment stability along the entire spine. They act like tiny, intelligent guy wires, constantly adjusting to keep each joint protected and aligned. They are essential for proprioception—the horse’s awareness of its body in space—and core control.
While we need the big mobilizers for power, the spine is vulnerable without the deep stabilizers. A horse with weak multifidus muscles may have a well-developed longissimus but will struggle to maintain posture, carry the rider’s weight effectively, and transfer energy from the hindquarters through a stable spine. This often leads to a hollow back, poor transitions, and difficulty with true collection.
What Science Tells Us About Activating the Core
Knowing these muscles exist is one thing; activating them is another. Groundbreaking research shows that specific, targeted exercises are highly effective at engaging these deep spinal muscles. A 2014 study in the Equine Veterinary Journal used electromyography (EMG) to measure muscle activity during various groundwork exercises.
The findings were clear: dynamic mobilization exercises, often called “carrot stretches” or “belly lifts,” significantly increased the cross-sectional area and activity of the multifidus muscles. This means these simple, non-ridden movements are more than just “stretches”—they’re powerful tools for neuromuscular activation. They teach the horse how to consciously engage the very muscles required for lifting its back and stabilizing its spine, an essential prerequisite for healthy movement under saddle.
Groundwork That Builds a Stable Core
The best part is that you don’t need fancy equipment to begin activating your horse’s core. These proprioceptive exercises take only a few minutes a day and lay the foundation for a stronger, more stable back.
The Belly Lift (Thoracic Lift)
This exercise directly targets the muscles responsible for lifting the mid-section of the back (the thoracic and lumbar spine) to create that desired upward curve.
How to do it:
- Stand safely at your horse’s side, facing their belly.
- Use your fingertips or a soft object like a capped pen to apply gentle, upward pressure along the midline of their abdomen, just behind the girth area.
- Slowly increase the pressure, “tickling” or scratching upward until you see your horse reflexively lift their back.
- Aim for a smooth, rounded lift, not a sudden, tense hump. Hold the lift for 5-7 seconds, then release the pressure and let your horse relax. Repeat 3-5 times.
What to look for: A visible lift through the withers and loin, with the pelvis tucking slightly. The goal is a controlled muscular engagement, not a startled reaction.
Carrot Stretches (Lateral and Rounding Stretches)
These dynamic movements activate the multifidus muscles while improving flexibility and body awareness. Use a small piece of carrot or a treat to guide your horse’s nose.
- The Chin-to-Chest Stretch: Encourages rounding of the neck and lifting at the base of the withers.
- Hold the treat between the front legs and ask your horse to lower their head and reach for it.
- The Lateral Stretch (to the Hip): Activates the multifidus on the opposite side of the bend while stretching the near side.
- Stand by your horse’s shoulder and guide their nose back toward their flank or hip. Encourage a smooth, even curve through the neck and body.
- Hold for a few seconds. Repeat on both sides.
The key is slow, controlled movement. You want your horse to stretch and engage, not snatch and twist.
From the Ground to the Saddle: Connecting the Dots
So, how does this groundwork translate to your ride?
Activating the multifidus muscles on the ground primes the neuromuscular pathways. The horse develops a muscle memory for lifting its back and engaging its core. When you get in the saddle, this new pattern of self-carriage is more accessible.
However, this is where the system can break down. All this valuable core activation can be instantly shut down if the saddle inhibits the very movement you’ve been training. If a horse lifts its back into a saddle that is too narrow, pinches the withers, or has rigid panels, the resulting pressure sends a clear signal: “Don’t lift! Hollow out to escape the pain.”
This highlights the importance of saddle fit not just for preventing sores, but for enabling correct biomechanics. A saddle must provide clearance for the spine and shoulders, allowing the back to rise and function without restriction. At Iberosattel, this principle is why we developed our Comfort Panel design; it’s engineered to create a generous channel and a flexible contact surface, giving the horse’s back the freedom it needs to lift and engage.
Ultimately, a stable equine core works in harmony with the rider. As your horse learns to stabilize its spine, it provides a more consistent platform for you, making it easier to maintain your own position. This creates a positive feedback loop where your stable rider’s seat and balance further encourages your horse’s self-carriage.
True strength isn’t just about building bigger muscles; it’s about awakening the deep, intelligent systems that create stability from within. By focusing on the multifidus, you are investing in the foundation of your horse’s comfort, soundness, and performance for years to come.
Frequently Asked Questions (FAQ)
Q1: How often should I do these core activation exercises?
A: Consistency is key. Aim to incorporate these exercises into your routine 3-5 times per week. They make an excellent warm-up before a ride or can be done on their own during a grooming session. Just a few minutes each time is enough to make a difference.
Q2: My horse is resistant to the belly lift. What should I do?
A: Resistance can indicate a few things. First, ensure you are being gentle enough—it’s a cue, not a poke. Try different tools, like the soft bristles of a brush. If your horse remains sensitive or pins its ears, it could be a sign of underlying soreness in the back or girth area. It’s always wise to consult your veterinarian or bodyworker to rule out pain.
Q3: Can these exercises replace ridden work for strengthening the back?
A: No, they are a complement, not a replacement. These groundwork exercises activate and prepare the deep stabilizing muscles for the demands of carrying a rider. Ridden work, especially correct flatwork, is still necessary to strengthen the larger “mobilizer” muscles and build cardiovascular fitness.
Q4: Is this the same as just building a stronger topline?
A: It’s a critical component of it. A strong topline is more than just the longissimus dorsi. A truly functional topline includes a strong, stable core underneath. These exercises target that deep foundation, allowing the larger muscles to work more efficiently and without straining spinal structures. You cannot have a truly healthy topline without a stable core.
