The open water will require you to mix up your stroke rate, so you might as well practice in the pool.

Change up your stroke rate to crush open water swimming. Here’s how.

Swim coach Frank Sole refers to the local lap pool as a petri dish (but not in a gross way): “It is a perfect environment: Same length, no waves, no sun, no wind, you can see the bottom, and generally the water is crystal clear.” In these conditions, an athlete can swim long, relaxed, and undeterred, which is great—but also not so great.

“On race day, you are now in the water with a couple thousand of your closest friends. Your wave is packed solid with athletes,” Sole explains. “You can’t always take those long and relaxed swim strokes. You’ll need to swim with a short stroke until you find clean water again.”

This concept illustrates what is known as stroke rate, or the amount of strokes an athlete takes in a certain duration, usually one minute, where one left arm pull counts as one stroke, one right arm pull counts as two, and so on. One swimmer’s rate may be 64 strokes per minute (SPM), that is, they take 64 single arm strokes per minute, while another’s might be 75 SPM. Whatever the number, it’s important to know that this isn’t something that’s set in stone. A swimmer should have an arsenal of stroke rates for various conditions, Sole says.

“Whether you’re in a crowded swim start, swimming around another athlete, or swimming around a turn buoy, you will have to adjust your stroke rate,” he says. “If there is a tide or current, this can and will have an adverse effect if your stroke rate is too slow.”

In other words, trying to maintain your standard relaxed pool stroke rate in non-pool environments is the equivalent of trying to take long running strides around corners or up hills. Being able to maintain a higher stroke rate gives you the ability to own your environment. For example, you might need to up your stroke rate in choppy conditions in order to punch through the water and not lose speed.

But it’s not always as simple as speeding up your arms when the need arises. “Remember a higher stroke rate will demand more oxygen, stressing the energy system, and using muscular strength and general mobility,” Sole says. “Technique can fall apart if you’re not careful.”

That’s why athletes should practice a higher rate in the pool on a regular basis—but only after the fundamentals have been mastered. “Early on with newbies, I tell athletes to give the stroke the necessary time to improve, along with your energy system. In time, we can incorporate tools like the tempo trainer [a metronome for swimmers] to set you on the path to a higher effective and efficient stroke rate.”

Stroke Rate: The Sweet Spot

Is there such a thing as a “perfect” SPM? Yes and no, says Sole: “In my experience, I have seen athletes in all distances from sprint to Ironman holding a stroke rate of approximately 48-60 strokes per minute.” That’s a wide range, and athletes shouldn’t be discouraged if their stroke rate is on the lower end.

Sole says athletes should be more concerned about keeping technique intact—an improvement in rate often follows naturally. In time, you can shoot for 72. “When I can get an athlete to hold 72 strokes per minute and do it without compromising the integrity of their technique, I consider that the ‘sweet spot.’”