Between rain showers on the Santa Monica beach, we march beneath the palms at a fast walk, striding in coordination with stabs from our modified ski poles. My brow beads with sweat, rare for being just minutes into a stroll over flat ground.

"It's Nordic walking," our teacher, Malin Svensson, tells a curious onlooker behind us now on the sidewalk as we start up a hill. Our measured pace begins as a groove but is now my enemy as I try to keep time up the sustained grade. At the top, my pulse hits 180 — a high-intensity workout without running a step.

Svensson waits for me to cool down and then tries an experiment: I walk back down the hill without my poles, rest and then walk back up at the same pace as before. I try hard, but at the top my pulse is just 150.

Fitness researchers at the Cooper Institute in Dallas, a nonprofit health and education research center, have found that walkers with poles using proper Nordic technique typically burn 40% more calories than regular walkers.

Another major benefit of Nordic walking is what fitness scientists like to call "perceived rate of exertion." Put another way, Nordic walking delivers a high-intensity workout for your body while feeling more like a sustainable walk in the park.

I can attest: At the top of the hill, my pulse was racing. I was panting for air, but not exhausted and dizzy as if I'd been running for my life.

Svensson came to America from Sweden in 1989, a track and field athlete who graduated into physical training and education. Her brother urged her to try Nordic walking, and in 2002 she became the first female instructor in the United States, she says.

I was getting an advanced version of lessons offered at 10 a.m. most Saturdays on the grass near Perry's, at the terminus of Ocean Park Boulevard. The day before our climbing session, I learned the basics with several other students, starting with a focus on stretching the ankle, leg and lower back muscles. The poles serve as tripods of support for the stretching exercises.

We also learned to strap the poles correctly to our wrists. The import of that wasn't clear until we began walking. With each stride, one hand releases its pole just behind the hip while the other hand swings forward into a pole plant, the hand grasping the pole just as it makes contact with the grass, pavement or sand. If you aren't strapped in snugly, it's hard to release and grasp again without messing up.

The International Nordic Walking Assn. claims 3 million worldwide enthusiasts, mostly in Sweden and Finland, where the activity was developed in the 1930s by off-season skiers looking to stay in shape.

The sport was updated in 1997, when ski equipment maker Exel introduced specialized Nordic walker poles, which have Velcro straps and differ slightly from trekking poles. The extra webbing is crucial to keeping the pole positioned when the palm is closed or open.

The poles include rubber caps on the tips for use on hard surfaces, such as pavement. You can remove the caps to get traction while walking on softer surfaces such as grass.

As a skier hoping to save my knees for the slopes, I liked the fact that Nordic walking got my heart rate up without the joint strain that a high-intensity activity such as running might cause. The weight a leg bears in a running stride is at least three times greater than the stress borne by a walker's step, according to Svensson.

Once incorporating the poles seems natural, our mantra is to keep an "active core" — upright posture with a taut but not overly clenched abdomen as a base of support for the trunk twisting that each stride involves. The movement comes from the core and not the arm muscles, leading to a more complete workout.

From a casual glance, these nuances are not apparent, leading to smirking questions from onlookers about snow blindness.

While Nordic walking is comfortable in a herd, a lone expedition takes a measure of courage if you're not personally promoting the sport like Svensson, whose teaching business in Santa Monica has spread mostly by word of mouth.

In reality, Nordic walking is too fast for any wisecracking bystander to keep up with without breaking into a jog. Still, on my first solo outing, I sneaked over to a lonely stretch of beach where any catcalls would be drowned out by the surf.

On sand, the experience is more intense. Grass or a trail is easier to handle. Once the moving parts come together, it's not effortless to maintain without concentrating. Yet in other ways it feels perfectly natural, like the way a child instinctively leans forward to scramble up a mound of dirt or sand.

After the first few outings, my triceps and abdomen were stiff, but stretching helped ease the soreness. The best part was the intense workout I got without running, a lifetime of which forced my father to have knee surgery twice.

Once you get the basics down, there is a higher level of Nordic walking for athletes that involves jumping and interval training. For now, walking a lonely beach in the dark and coming away with a workout is good enough for me.