Suiting up for swimming is as simple as seeking an aerobic exercise that's gentle on the joints.

Suiting up for swimming is as simple as seeking an aerobic exercise that's gentle on the joints.

Sticking with swimming after the first few laps is a matter of redefining the pool's boundaries with workouts that combine variety and repetition to unlock the sport's cardiovascular potential.

"We aren't designed for water," says Jim Heath, swimming coach for Phoenix High School. "It's not as enjoyable when it's so hard," he says, adding that many newcomers to the sport lose interest after just a few days.

Getting comfortable in a pool is the first hurdle, he says. Survival instincts compel humans to keep their heads up when navigating water, trailing their hips and legs at a downward angle. New swimmers should concentrate on putting their heads down, immersing the face and eyes, and rolling the head to breathe without changing the neck's angle.

Closer to parallel with the water, the body moves more efficiently. It's a position that comes with practice and is usually more comfortable with goggles. Breathing every third stroke on alternate sides of the body keeps the motion consistent while preventing strain to one side of the neck.

"If you feel like you're swimming uphill, you're making it too hard on yourself," Heath says.

Swimming novices, Heath says, should focus on traversing a length of the pool — 25 yards is standard for most — without stopping. As endurance improves, swim two lengths — or a lap — without rest.

When swimmers string together lengths of the pool in this manner and repeat the distance in regular intervals, their workout is based on the concept of sets, similar to repetitions of a particular weight-lifting exercise, Heath says. It's common for longtime swimmers to work on sets of 100s (four pool lengths) or even 200s (eight lengths), he says.

"Rest 30 seconds and then do it again."

As with any aerobic exercise, swimming should be performed at about 70 percent of one's maximum heart rate, which usually can be determined by subtracting one's age from the number 220, Heath says. To build cardiovascular strength, he recommends resting for half the time spent swimming, reducing rest by five seconds per set as fitness improves. Before leaving the pool, swim a few "cool-down" lengths until the heart rate returns to normal, Heath adds.

Seasoned swimmers may swim several miles in a single workout, but Heath advises beginners to aim for swimming 30 to 60 minutes at their target heart rate, resting as needed, two to three days per week. Once swimmers establish a routine, they can work out more days each week and increase their distance using a formula that runners favor: Go 10 percent farther than you did the week before.

Although swimming's main attribute as a full-body, heart-healthy regimen may be likened to running, swimming doesn't offer running's range of terrain or scenery. Would-be swimmers have to reconcile themselves to exercising in a small, limited environment that can foster boredom, Heath says.

"Round and round we go," he says. "We want to mix it up."

That's where equipment, such as fins, kickboards and pull buoys, comes in. Incorporating them into a swimming workout not only diversifies the experience but forces certain parts of the body to work harder and ultimately improves body position and technique, Heath says. It may seem like cheating to swim with fins, but they actually increase the load on leg muscles and promote ankle flexibility, which drives a strong kick.

"Yes, you go faster, but you're also working harder," Heath says. "The kicking is another thing that's gonna be real important for body position."

It's normal to cramp when using fins, but Heath encourages new swimmers to work through the discomfort for short distances before removing the fins and continuing to swim normally. Fins should be the shortened type designed for swimming, not scuba diving or snorkeling, he adds. Zoomers are a common brand and can be purchased, along with basic models of other equipment, online and at local sporting goods stores, including Rogue Scuba, Heath says.

Specialized equipment also helps new swimmers learn specialized strokes: backstroke, breaststroke and butterfly. Adding these to the "crawl," or freestyle, in a swimming repertoire keeps a pool workout interesting, compels the body to adapt and propels fitness forward.