The crawl stroke, commonly called freestyle, is the fastest and most efficient swimming stroke. It involves alternating overarm pulls combined with a flutter kick while lying face down in the water, rotating your body side to side with each stroke cycle. It’s the default stroke in competitive freestyle events and the one most recreational swimmers eventually learn after breaststroke.
Origins of the Crawl Stroke
Over-arm swimming strokes existed long before modern competitive swimming. There’s evidence that the Assyrians and Greeks used an over-arm technique at least 800 years before Christ, and variations of the crawl were the natural swimming style of South Sea Island natives, North American Indians, and the Kaffirs of South Africa.
Modern competitive swimming started in England in 1837 with breaststroke as the dominant racing style. That changed on August 11, 1873, at the Lambeth Baths in London, when an Englishman named John Trudgen won a 160-yard race by swinging both arms alternately over the water. He paired this with a horizontal breaststroke kick, creating a jerky but remarkably fast stroke he said he’d learned from South African swimmers during his childhood abroad. This “Trudgen stroke” made him the fastest sprinter of his era.
Australian swimmers later refined the technique. Fred Lane developed a version with a narrow, whip-like scissors kick and won the 200-meter freestyle at the 1900 Paris Olympics. Over the following decades, the scissors kick was gradually replaced by the flutter kick we know today, completing the evolution into the modern crawl stroke.
How the Arm Stroke Works
Each arm moves through four distinct phases in a continuous cycle: entry and catch, pull, push, and recovery. The pull and push phases are the propulsive ones, meaning they’re what actually moves you forward. The other two phases reposition your arm for the next stroke.
During the entry, your hand slides into the water fingertips first, roughly in line with your shoulder, then reaches forward to “catch” the water. The pull phase draws your hand back under your body in a slightly curved path, engaging your forearm muscles and upper back. The push phase continues that motion past your hip, finishing the underwater portion of the stroke. Recovery is the above-water return: your elbow lifts first, your hand swings forward relaxed, and the cycle starts again. Your arms alternate so that one is always pulling while the other recovers.
The Flutter Kick
The flutter kick is a rapid, alternating up-and-down movement of relatively straight legs over a small range of motion, roughly 12 inches of depth. Your legs work in opposition: when one kicks down, the other kicks up.
The downbeat is the power phase. It’s driven by your quadriceps (extending the knee) and hip flexors (pressing the thigh down), and it produces most of the kick’s propulsive force. The upbeat, powered by your hamstrings and glutes, is primarily a setup for the next downbeat. A strong downward kick also shifts the same-side hip upward, which helps smooth out your body rotation from side to side.
Swimmers use different kick rhythms depending on speed and distance. A two-beat kick (one kick per arm stroke) is common for distance swimming because it conserves energy. A six-beat kick (three kicks per arm stroke) is more common in sprints, providing greater propulsion and tighter body control. Four-beat patterns exist too, though they’re less standard. All effective kick patterns have a two-beat foundation at their core.
Breathing and Head Position
Breathing in the crawl stroke happens by rotating your head to one side as your body naturally rolls during the stroke. The key is rotating your head rather than pulling or lifting it sideways. Lifting your head disrupts your spinal alignment, which creates drag and often causes your hips to sink.
Timing matters. Your breath should coincide with your body’s rotation, not with your arm recovery. A common mistake is waiting too long to return your head to the water after breathing, keeping it turned until the recovering arm comes forward. Learning to return your head independently of your arm improves both your alignment and your stroke rhythm.
Some swimmers breathe to one side every two strokes, others breathe bilaterally (alternating sides, typically every three strokes). Either approach works. Even if you prefer one side, occasionally practicing the other side during workouts helps build symmetry in your stroke and can actually improve your breathing on your preferred side by giving you a different feel for the movement.
Body Position and Drag
The single biggest factor in crawl stroke efficiency is your body’s angle in the water. The less horizontal you are, the larger the cross-section of your body pushing against the water, and the more energy you waste overcoming drag. The goal is to stay as narrow and horizontal as possible on the surface.
Head position controls this more than almost anything else. When you lift your head, your hips drop. If you then try to compensate with harder kicking, your kick is providing lift instead of forward propulsion, wasting energy twice over. But pressing your chin down onto your chest isn’t the answer either. The ideal head position is somewhere in between, and you can find it by experimenting: the right spot is wherever your hips stay near the surface when you’re not actively kicking.
Muscles Used in the Crawl Stroke
The crawl stroke is effectively a full-body exercise. Your deltoids and shoulder muscles control hand entry and your forward reach. Your forearm muscles generate pulling force underwater. Your upper back muscles, particularly around the shoulder blades, stabilize your shoulders throughout each stroke cycle. Your core muscles manage the rotational movement that connects your upper and lower body. And your glutes and hamstrings keep your body balanced while powering the upbeat of the kick, with your quadriceps and hip flexors driving the downbeat.
Calorie Burn and Efficiency
For a 140-pound adult, the crawl stroke at a light to moderate effort burns roughly 370 calories per hour. At a medium to vigorous pace, that jumps to about 530 calories per hour. A fast, all-out effort pushes it to around 620 calories per hour. These numbers scale up with body weight.
Compared to other strokes, the crawl produces the most speed for the least energy when done with good technique. This comes down to drag: because your body stays horizontal and streamlined, with continuous (rather than stop-and-start) propulsion from alternating arms, less energy is lost to water resistance than in breaststroke or butterfly.
Common Technique Errors and Shoulder Health
Shoulder pain is the most common overuse injury in swimmers, and it’s usually tied to stroke mechanics rather than just training volume. Two opposite errors cause the same problem. Crossing your hand past the midline of your body during the pull (often from too much body roll) forces your shoulder into an impingement-prone position. Too little body roll does the same thing, because your arm compensates by sweeping inward to find enough water to push against.
The fix for both is balanced body rotation, roughly 30 to 45 degrees to each side, so your arms can pull along a path that keeps the shoulder joint in a safe range. Strengthening the muscles around your shoulder blades also helps. Exercises that train scapular stability, like wall push-ups with an extra push at the top (a “supine punch” movement), build the support structures that protect the joint during thousands of repetitive stroke cycles.
Competitive Freestyle Rules
In competition, “freestyle” technically allows any stroke, but the crawl is universally used because it’s fastest. World Aquatics (the sport’s governing body) imposes two main rules specific to freestyle: your head must break the surface by the 15-meter mark after every start and turn, and you cannot be completely submerged during the stroking portion of the race. Beyond that, the stroke is largely unregulated, giving swimmers flexibility in their technique as long as they stay on the surface and keep moving.