Swimming: The Complete Guide for Swimmers, Parents and Coaches

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The smell of chlorine at 5:30 a.m. and a clock ticking on the wall. A summer-league meet with popsicles on the pool deck. A high school relay team pounding on the blocks while their anchor swimmer heads for the wall. Masters swimmers in their sixties finishing a 3,000-yard workout before work, and a pack of caps heading out past the buoys in a lake. Swimming is one sport with many lives: a life skill every child should learn, a year-round competitive sport, an Olympic headline event and a way to stay fit for a lifetime.

This page covers swimming for athletes and the people who look after them: how competitive swimming works, what it looks like at every level from summer league to the Olympics, and, most of all, how to stay healthy doing it. Sports health is at the center. We cover the shoulder pain that comes with high training volume, low back and ear problems, the breath-holding drills that can be deadly, and how to keep kids safe around water. Then come training, recovery and the gear you need.

Swimming at a glance

Strokes	Four competitive strokes: freestyle, backstroke, breaststroke and butterfly. The individual medley (IM) uses all four.
Pools	Long course: 50 meters (the Olympic pool). Short course: 25 meters. US high school and college meets are mostly in 25-yard pools.
Events	From 50-meter sprints to the 1500 freestyle in the pool, plus relays. Open water races run up to the Olympic 10 km marathon swim and beyond.
Governing bodies	World Aquatics worldwide; USA Swimming for clubs and the national team; U.S. Masters Swimming for adults; NFHS for high school; NCAA, NAIA and NJCAA for college.
Who swims	376,479 USA Swimming members in 2024; nearly 60,000 Masters swimmers; 257,405 high school swimmers and divers in 2024–25.
Most common injuries	Shoulder pain from repetitive motion (by far the most common), low back pain, swimmer’s ear and other overuse injuries.

How competitive swimming works

Races are swum in lanes, and the fastest time wins. Each stroke has rules that officials called stroke-and-turn judges watch closely. In freestyle you can swim any style, and almost everyone swims front crawl. Backstroke is swum on the back. Breaststroke and butterfly are swum on the front, with both arms moving together, and you must touch the wall with both hands at every turn and at the finish. In freestyle, backstroke and butterfly, a swimmer may stay underwater for up to 15 meters after the start and each turn, and then the head must break the surface.

Races start from the blocks with a dive, except backstroke and medley relays, which start in the water. Under World Aquatics rules a swimmer who starts before the signal can be disqualified; there’s no second chance. The individual medley goes butterfly, backstroke, breaststroke, freestyle. A medley relay goes backstroke, breaststroke, butterfly, freestyle, so the backstroker can start in the water. Our swimming rules page explains every stroke, start and turn in plain words.

Open water swimming happens in lakes, rivers and the sea, usually around a course marked by buoys. World Aquatics requires wetsuits in its races when the water is below 18°C (about 64°F) and treats 16°C (about 61°F) as the minimum safe temperature. The 10 km marathon swim has been an Olympic event since Beijing 2008.

Swimming at every level

Learning to swim and kids’ swimming

Every swimmer starts with lessons. In its updated drowning-prevention policy (2026), the American Academy of Pediatrics (AAP) says swim lessons can begin after age 1 and that “swimming can be a child’s first sport.” The CDC notes that formal swim lessons can lower the risk of drowning. Lessons are only one layer, though: kids still need supervision every time they’re near water. From there, many children join a summer league, a YMCA team or a year-round USA Swimming club. USA Swimming’s biggest age group in 2024 was 8 and under, with 41,777 members. Our youth swimming guide covers drowning prevention, age-group swimming and what parents ask most.

High school

High school swimming and diving follows rules from the National Federation of State High School Associations (NFHS). The standard championship program is swum in yards: the 200 medley relay, 200 and 500 freestyle, 200 IM, 50 and 100 freestyle, 100 butterfly, backstroke and breaststroke, the 200 and 400 freestyle relays, and 1-meter diving. In 2024–25, 138,303 girls and 119,102 boys took part, which made it the 9th most popular high school sport for girls and the 10th for boys.

College

The NCAA runs swimming and diving championships in Division I, II and III, held in March. In 2026, the Division I women raced March 18–21 and the men March 25–28, both at Georgia Tech in Atlanta. The NAIA and the NJCAA (two-year colleges) crown their own national champions too. Under the House v. NCAA settlement, Division I schools that opted in now have a roster limit of 30 swimmers and divers per team.

Elite, Olympic and Paralympic

World Aquatics, which has 210 national member federations, runs the World Championships. The next one is in Budapest in 2027, with pool swimming from July 10 to 18. The US team also raced at the Pan Pacific Championships in Irvine, California, on August 12–15, 2026. At the Los Angeles 2028 Olympics, swimming grows to 41 medal events, up from 35 in Paris, because the 50 m backstroke, breaststroke and butterfly have been added. The pool will be built inside SoFi Stadium. Para swimmers race in classes S1–S14, grouped by type and degree of impairment. Our leagues and associations page maps all of it.

Masters and adult swimmers

In swimming, “Masters” simply means 18 and older. U.S. Masters Swimming (USMS) serves nearly 60,000 members in more than 1,200 clubs and workout groups. Racing is optional: many members swim for fitness and company, and some just want a coach on deck writing the workout. Many clubs run adult learn-to-swim programs too, so it’s never too late to start.

Sports health for swimmers

Swimming is low-impact, but it isn’t injury-free. The big risk is repetition: a competitive swimmer can take thousands of strokes in a single practice. This section is general information, not medical advice. If something hurts, see a professional. Our swimming injuries page goes deeper.

The most common swimming injuries

• Swimmer’s shoulder: the American Academy of Orthopaedic Surgeons (AAOS) calls shoulder pain from repetitive motion the most common swimming injury. In a study of 80 elite swimmers aged 13–25, 91% reported shoulder pain. Supraspinatus (rotator cuff) tendinopathy was the main cause, and it was linked to hours swum per week and weekly distance.
• Overuse injuries in college swimmers: NCAA injury surveillance found most swimming and diving injuries hit the shoulder, were strains, and came from overuse or non-contact. Female swimmers had a higher overuse injury rate than male swimmers.
• Low back pain: a 2024 review calls spine injuries the second most common musculoskeletal injury in swimmers. It points to the arched-back undulation of butterfly and breaststroke, high training loads and tired trunk muscles. Most cases are treated without surgery, with physical therapy and training changes.
• Swimmer’s ear: an infection of the outer ear canal when water stays in it too long. The CDC suggests a cap, ear plugs or custom swim molds, drying the ears well after swimming, and never putting cotton swabs or other objects in the ear canal.
• Head and neck injuries: AAOS also lists concussions, dislocations and fractures, many from collisions with walls or other swimmers, and warns never to dive into shallow or murky water.

Event matters too. In a 2026 study of 196 elite Scandinavian swimmers, the shoulder was again the most common injury site, and freestyle sprinters were injured about twice as often as distance freestylers. To protect the shoulder, AAOS recommends a general exercise program to strengthen the muscles around the shoulder and upper back. For fitness swimmers it also suggests a 5–10 minute warm-up on land and staying out of hard sessions when you have a fever or an ear infection.

Breath-holding: the danger every swimmer should know

Hyperventilating before an underwater swim, or doing long breath-holds and “how far can you go underwater” contests, can make a swimmer black out without warning. USA Swimming, the American Red Cross and the YMCA of the USA call this hypoxic blackout, and their joint statement asks coaches and lifeguards to stop swimmers from hyperventilating and doing extended breath-holding. Swimmers are also told not to practice breath-holding drills on their own, even when a lifeguard is on duty.

Concussion: recognize and remove

Concussions are less common in the pool than on a field, but a swimmer can hit a wall, a lane line or another swimmer. The CDC’s HEADS UP advice is the same for every sport: if a swimmer looks dazed or reports a headache, dizziness or blurry vision after a knock, take them out of the water and keep them out for the rest of the day. They shouldn’t return until a health care provider clears them. Call 911 for danger signs such as a seizure, passing out, a headache that keeps getting worse or one pupil larger than the other.

Water safety, even for good swimmers

Drowning is the leading cause of death for US children aged 1 to 4, and the CDC counts about 4,000 fatal unintentional drownings a year, about 11 a day. Good swimmers aren’t immune. The AAP warns that teens tend to overestimate their skills, and the CDC notes that among people 15 and older, almost half of drownings happen in natural water. For open water, AAOS’s basics apply: don’t swim alone, swim where lifeguards are on duty, check the weather and skip alcohol.

When to see a doctor, physical therapist or athletic trainer

See a professional for shoulder pain that lasts after rest or keeps coming back, pain at night, a shoulder that feels unstable, back pain that runs down a leg, numbness or tingling, ear pain or discharge, or any concussion signs. A sports medicine physician manages most sports injuries without surgery. A physical therapist can check your stroke mechanics and build a rehab and strength plan. If your high school or college team has an athletic trainer, start there.

Training and conditioning for swimming

Swim training is built on yardage, but more isn’t always better: in the elite-swimmer study above, more hours and more distance went with more shoulder tendinopathy. Good programs build volume gradually, mix in technique work with tools like a kickboard, fins and a snorkel, and add dryland training for the shoulders, upper back and core, the areas AAOS and the low-back review single out. Our swimming training page covers seasons, sets and dryland.

Many swimmers track heart rate, sleep and recovery with a wearable (see Whoop vs Oura vs Garmin and HRV for athletes), and our best swimming wearables page covers watches made for the pool. For meet days, the sports-nutrition position statement from the American College of Sports Medicine and two dietitians’ groups recommends a familiar pre-exercise meal that is high in carbohydrate, moderate in protein and low in fat and fiber, eaten about 1–4 hours before. Swimmers sweat even though they’re in water, so keep a bottle on the pool deck; on long meet days many add electrolytes (see our electrolyte powder guide). More in swim meet day and swimming nutrition and supplements.

Recovery after practice and meets

Early-morning practices make sleep the first recovery tool. The CDC, citing the American Academy of Sleep Medicine, recommends 9–12 hours a night for children 6–12, 8–10 hours for teens and 7 or more for adults. Swimmers with a 5 a.m. alarm need an early bedtime to get there. After practice, eat a real meal or snack with carbohydrate and protein; a protein shake can help when a meal is hours away (see our protein powder guide).

Many swimmers use a foam roller or a small massage gun for tight lats, chest and legs, and slip into soft recovery shoes for long days on a wet deck. These are comfort tools, not treatment; shoulder pain that doesn’t go away needs a professional. More in our swimming recovery page and recovery tools guide.

Gear for swimming

• Suit: a durable practice suit for training. Under World Aquatics rules, racing suits must be approved, can’t go below the knee, and for men can’t go above the navel. USA Swimming bans tech suits for swimmers 12 and under at most meets.
• Goggles and cap: World Aquatics rules allow goggles. A silicone cap keeps hair out of the way and, with ear plugs, helps keep water out of the ears.
• Training tools: kickboard, pull buoy, fins, paddles and a center-mount snorkel. Most clubs list the ones they want.
• Open water: a bright cap, a wetsuit when the water is cold, and a buddy.

Three picks for any swim bag: the Speedo Vanquisher 3.0, a low-profile racing and training goggle with anti-fog lenses and interchangeable nosepieces; Mack’s AquaBlock ear plugs, reusable silicone plugs that Mack’s says are the official ear plugs of USA Swimming; and the OOFOS OOahh Slide from our recovery shoes guide, for the walk from the pool to the car. Our swimming gear guide has the full list, including tech-suit rules for age-groupers.

For more recovery gear, browse Recovery & Regeneration and Training & Performance.

Swimming FAQs

What age should kids start swimming lessons?

The AAP says swim lessons can start after a child’s first birthday. They lower drowning risk but don’t make a child “drown-proof,” so lessons go together with constant, close supervision, fences around pools and life jackets near open water.

What are the four competitive swimming strokes?

Butterfly, backstroke, breaststroke and freestyle, the order of the individual medley. Freestyle allows any style, but in a medley event it means any stroke other than the other three.

How long is an Olympic swimming pool?

50 meters, called long course. World Championships-level pools have 10 lanes at least 2.5 meters wide. Short-course pools are 25 meters, and most US high school and college pools are 25 yards.

What is swimmer’s shoulder?

It’s the common name for shoulder pain from the repetitive overhead motion of swimming, most often from irritation of the rotator cuff tendons. In elite swimmers it was tied to training volume. Persistent shoulder pain is a reason to see a sports medicine doctor or physical therapist, not to swim through it.

How can I prevent swimmer’s ear?

The CDC suggests a swim cap, ear plugs or custom molds, tilting your head to drain each ear and drying it with a towel after swimming. Don’t put cotton swabs in the ear canal. Ask your doctor about ear-drying drops if you get it often.

Can adults start competitive swimming?

Yes. U.S. Masters Swimming is open to anyone 18 and older, from beginners to former college swimmers, and racing is optional. Many clubs also run adult learn-to-swim classes.

Swimming can last a lifetime, from a toddler’s first lesson to a Masters relay at 80. The swimmers who keep going are the ones who build up gradually, strengthen their shoulders, sleep, eat and take pain seriously. Keep exploring: our recovery tools guide, electrolytes and Nutrition & Supplements for meet days, and the other sports on our sports hub.