I received a question from a leading swimrunner a few weeks back. It was not about intervals, volume, or strength: it was about rotation.

As swim coaches we talk a lot about technique, long strokes, hip drive, reach, and glide. But swimrun is not normal swimming. The equipment changes the physics, and when the physics change, the optimal technique may change with it.

The question was simple and sharp: If rotation improves efficiency in normal freestyle, what happens when you add a pull buoy, paddles, and shoes? Does rotation still give a net gain, or does the added drag and instability make a large roll mechanically expensive?

I am not aware of any paper that has studied rotation in swimrun swimming, but that does not mean we are guessing. We can reason from mechanics, and when you do, something interesting emerges. This is not just about rotation: it is about how swimrun forces us to evolve beyond copying no-gear technique and instead adapt to a different physical system.

All freestyle rotates around the long-axis (an imaginary line running from your head to your toes, like a rotisserie spit). The real question is how much, and where that rotation originates. There are two primary archetypes:

The kick stabilizes roll, yaw (the side-to-side swinging of your legs), and timing. Remove the kick and the system becomes less stable. Add a buoy and its primary effect is not just buoyancy, but transverse stability and a shift in pivot points.

It is important to distinguish between a "standard" buoy and a "swimrun" buoy. A standard buoy provides modest lift, but a modern swimrun buoy (like the Ark Keel Mega) provides massive buoyancy, often three to four times that of its traditional counterpart. This extreme lift creates a powerful restoring torque (a force that aggressively pushes you back to a flat, horizontal position). It effectively pins the hips to the surface like a rigid stabilizer.

Because the hips are locked to the surface, the swimrun buoy acts as a yaw fulcrum (a fixed pivot point). In no-gear swimming, the body can "snake" slightly to absorb energy, but the buoy creates a rigid point. If the torso rotates too violently, this pivot point forces the legs to swing out like a compass needle. The buoy translates messy roll into lateral drag.

Shoes sit at the end of a long lever relative to the axis of rotation. Rotational inertia (the resistance to being turned) increases with mass times the square of the radius. That "radius squared" term matters: a small mass far from the center of rotation dramatically increases the effort required to rotate or stop a rotation.

Consequently, shoes amplify the cost of the "compass needle" effect. When uncontrolled rotation causes the legs to swing laterally, the shoes present a large surface area to the water.

There is a subtle psychological trap here. Because the drag on the shoes is so high, the water actually "pushes" your feet back into line almost as soon as they swing out. This is a self-correcting system, but it comes at a massive cost. It is like tapping the brakes in your car every time you turn the steering wheel.

Because the shoes snap back into position so quickly, you might not even realize your legs are wiggling. To the swimmer, it does not feel like a "wobble," it just feels like a heavy, constant drag. You feel like you are swimming in a straight line, but you are wondering why other athletes are gliding past you with half the effort.

Put simply, shoes turn a small hip wiggle into an invisible, automatic brake.

In no-gear swimming, you can "fake" reach by rotating the whole cylinder. If you lack thoracic (mid-back) or shoulder flexibility, you simply roll your hips further to get your hand forward. This works because there is less penalty for a large, slow roll.

In swimrun, that strategy breaks down. Because the gear punishes large-amplitude rotation, you must find reach elsewhere. This is where scapular protraction (the ability of the shoulder blade to slide forward around the ribcage) becomes the ultimate advantage.

If your shoulder blades and mid-back move well, you can achieve a long stroke without a massive pelvic roll. This allows you to "project" forward from the ribcage while keeping your hips and legs perfectly quiet. If you lack this mobility, you will be forced to choose between a short, inefficient stroke or a large, high-drag roll.

As a curiosity, I have excellent shoulder mobility and I would argue I punch above my weight in pull paddle swimming: is it correlation or causation? Based on these mechanics, I would argue causation. My mobility profile matches the constraints of the gear, allowing me to maintain length without the instability that plagues less flexible swimmers.

When you rotate, you generate angular momentum (the "momentum of a turning object"). In no-gear freestyle, the kick helps dampen excess rotation. In buoy plus shoes swimming, the legs cannot counterbalance and increased inertia resists rapid changes in direction.

Because angular momentum must be conserved unless an external force is applied, and the kick is gone, the primary corrective force available to stop your roll is the opposite arm pull. This is often triggered by the hand entry and amplified by paddles.

To find balance, swimrunners often reach across their midline (the center of their body). This is a "cross-over." With the added surface area of a paddle, this cross-over creates a lateral force that initiates the very leg sway we want to avoid. A wider, "tracks-on-a-rail" entry is a prerequisite for maintaining a stable, low-rotation platform.

Paddles naturally slow down your Strokes Per Minute (SPM) because of the increased resistance. This creates a timing trap. If a swimmer has poor timing, they often fall into one of two errors that destroy the stability of the system:

In no-gear swimming, you can survive a "dead spot" in propulsion. In swimrun, you cannot. The moment propulsion stops, the massive buoyancy of the buoy and the drag of the shoes take over. Without the "tension" of constant forward motion, the body begins to snake or sink. To stay stable, a swimrunner needs a continuous, front-quadrant rhythm where one hand begins the catch just before the other enters. You are not just pulling for speed; you are pulling to keep the platform taut.

The Shoulder-Driven Disadvantage Natural shoulder-driven swimmers often have more difficulty adapting to paddles than hip-driven swimmers. Because their engine is built for a high-turnover rhythm, the forced drop in stroke rate caused by large paddles can feel like "stalling" a car engine. This is fundamentally a problem of optimizing the DPSxSPM equation (Distance Per Stroke multiplied by Strokes Per Minute).

For a naturally high-cadence swimmer, bigger paddles are often not worth the trade-off. Since they rely more on high-frequency turnover than on the deep rotational torque generated by the core and hips, oversized paddles can quickly overload the smaller stabilizing muscles of the shoulder. This leads to rapid fatigue and a breakdown in that vital continuous rhythm, ultimately decreasing their speed despite the increased surface area of the paddle.

In race conditions (cold water, high heart rate, and fatigue) stability becomes your primary performance limiter. In a pool, you are limited by how much power you can generate (propulsion). In swimrun, you are limited by how much of that power is lost to misalignment.

When your core fatigues, the gear actively tries to pull you out of a straight line. If you cannot maintain a stable platform, any extra effort you put into the pull simply increases your lateral sway. Because shoes turn even a small wiggle into a massive brake, your speed is effectively capped by your stability, not your strength.

This also changes breathing mechanics. In a low-amplitude stroke, the window for breathing is shorter. You can no longer rely on a big hip roll to "carry" your head to the air. It requires much more precision to peek for air without lifting the head and destroying your body position.

Yes, but the optimal amplitude (the size of the movement) decreases. The goal becomes minimal effective rotation. This should be enough to load the catch, protect the shoulder, and clear the breath.

However, we must be careful: flattening the stroke too much shifts load back toward the shoulder joint. This is where scapular mobility and control save the day: they allow you to maintain a long, healthy stroke on a stable, flatter platform.

As gear increases, the mechanical cost of large hip-led rotation increases. Therefore:

No-gear technique often maximizes reach; swimrun technique minimizes waste.

To understand your baseline, try these dry land mobility tests before your next swim.

The Mobility Baseline (Dry Land)

If you fail any of these tests, large hip-driven rotation is not a style choice: it is a compensation.

The Stability Challenge (In the Water)

Pro tip: For an even greater challenge, try using an ankle band in combination with your paddles and pull buoy. This dramatically increases your proprioception (your body's awareness of its position) and will make any lateral movement or "snaking" instantly noticeable.

Compare your stroke rate, pace, and perceived stability. You may find that the fastest option is not the biggest roll, but the most controlled one.

Swimrun does not reward aesthetic amplitude.

It rewards economy under constraint.