Note: This framework is primarily designed for adult-onset swimmers, triathletes, and swimrunners, for whom technical efficiency is the primary bottleneck to performance.

I recently received a question that perfectly captures why so many swimmers feel stuck:

The problem isn't the app or the watch. The problem is that most adults treat swimming like running: they assume that adding more distance or more heart rate is the only way to get faster.

Swimming doesn’t work like that.

Progressive overload is one of the most fundamental principles in endurance training. In running and cycling, it’s almost intuitive: you add time, distance, or power, and performance improves. The relationship between effort and output is reasonably linear, and progress is easy to see.

In the water, the usual levers of overload behave differently. Sessions are often time‑limited, technique collapses before fitness, and intensity doesn’t scale in a neat, predictable way. This is why many swimmers feel stuck; even when they’re training consistently and working hard.

Most swimmers don’t have unlimited training time. In most squads, sessions are fixed at 60 or 90 minutes. Unlike running, you can’t simply extend a session to create overload. The total volume is capped before you even start. This forces a different question: If I can’t train longer, what exactly am I progressing?

For the majority of adult-onset and sub-elite swimmers, fitness is rarely the first thing to fail. Technique is. As intervals get longer, stroke mechanics degrade. Once that happens, the swimmer is no longer training the intended system; they’re rehearsing inefficiency; adding fatigue without adding speed.

In most adult-onset swimmers, simply trying harder usually results in "fighting the water"; creating more turbulence rather than more propulsion.

Water is approximately 800 times denser than air. In fluid dynamics, drag force is proportional to the square of velocity. However, the power required to overcome that drag increases with the cube of velocity.

Why this matters:

Many swimmers are improving long before the clock confirms it. In water, small time gains are massive physiological wins.

Instead of thinking in terms of time or distance, progressive overload in swimming should be framed around control.

Structure training blocks by progressing interval length, not total volume. However, there is a golden rule here: Your intervals should map to your technical ability, not your fitness.

Even if you have the cardio to swim 1km straight, if your "form" falls apart after 50m, you should stop at 50m. By resting for 15 seconds, you reset your stroke so you're always "practicing" being fast and efficient, rather than practicing survival mode.

For swimrunners, paddles and pull buoys are not just "toys"; they are tools for specific force production and hydrodynamic proprioception.

For swimmers faster than roughly 1:45 / 100m, use Critical Swim Speed (CSS) as a reference point. For swimmers slower than ~1:45 / 100m, RPE (Rate of Perceived Exertion) and "relaxed speed" are more effective. At this pace, chasing a clock time often leads to "thrashing," which increases drag and reinforces poor mechanics. Focus on finding a "slippery" sensation instead.

Legendary coach Brett Sutton explains why this "broken" approach to distance is the secret to real speed:

There is a well-known story from the early career of Sutton. As a young coaching assistant, he was sent to observe a rival club that kept winning state championships. He expected to see complex, constantly changing workouts. Instead, week after week, he watched them do the exact same session. He eventually realized that champions aren't built on "variation" but on repetition under control. That "monotonous" set used by this world-dominating club was a Broken 500 Metres:

10 × 50 m on a fixed, tight start time, as:

A common misconception among amature marathon swimmers and multi-day athletes is that they must prove their readiness by swimming a very high percentage of their target distance in a single, continuous session. Many believe that if they cannot swim 8 km or 9 km straight in training, they are not ready for a 10 km event.

In reality, readiness for marathon distances is not determined by any single workout. It is primarily driven by consistent weekly volume. For most amateur athletes, weekly mileage will typically peak somewhere around 1.5 to 2 times the longest swim distance, depending on experience and training time.

In long-distance swimming, the greatest limiter is rarely aerobic stamina alone. It is the accumulation of drag caused by technical breakdown under fatigue. High-percentage simulation swims often become “death marches,” where the final kilometres are spent reinforcing slow, inefficient movement patterns.

Effective overload comes from accumulating large volumes of high-quality swimming across the week. Sessions broken into repeats with short rest allow swimmers to reset posture, maintain a horizontal profile, and preserve an effective catch. This results in better mechanics, higher average speed, and a stronger aerobic stimulus than a single continuous effort performed in a fatigued state.

Long continuous swims still have a role, particularly for nutrition practice, cold adaptation, and psychological preparation. However, they are tools for specificity, not the foundation of your training program.

When most swimmers plateau, they assume they need a different app or a more complex plan. In reality, the plateau is often mental.

Swimming requires a level of constant proprioceptive focus that running doesn't. You have to think about your hand entry, your hip rotation, and your kick timing simultaneously. As you get tired, your "mental bandwidth" shrinks. You stop "swimming" and start "surviving."

Progressive overload is also the training of focus. Holding your form for 200m instead of 100m isn't just a cardiovascular win; it’s a cognitive win. It means you've automated the movements well enough that they no longer require 100% of your conscious attention.

Progressive overload in swimming is not about doing more. It’s about doing better.

Swimming rewards patience and precision. The work often looks boring. The gains often feel invisible. Until one day, you realise you’re swimming faster than ever; without trying harder.