Swimming is easy on your joints, and being a safe swimmer takes five skills

Key takeaways

• Standing in water up to your navel takes about half your body weight off your legs, and chest-deep water takes off 60% or more³.
• A Cochrane review of 13 trials found that warm-water exercise improved knee and hip arthritis pain by about 5 points on a 100-point scale, a small but real short-term gain⁷.
• In a large British study, swimmers had a 41% lower risk of dying from heart and blood vessel disease, though healthier people may simply be more likely to swim⁴⁵.
• In a federal survey taken in late 2023, about 40 million U.S. adults said they can’t swim and 55% had never had a lesson, so learning the basics comes before laps²¹³.
• Pool chlorine doesn’t kill every germ quickly: the parasite Crypto can survive more than 7 days in properly treated water, so stay out when you have diarrhea¹¹¹².

In a 2014 survey for the American Red Cross, 80% of U.S. adults said they could swim¹. Then the pollsters asked about five basic water skills, such as treading water for a minute and swimming 25 yards to get out.

Only 56% of those self-described swimmers said they could do all five¹.

That gap matters in a way it doesn’t for walking or cycling, because running short on skill in deep water can end in drowning.

The problem hasn’t gone away. In a federal survey fielded in late 2023, about 40 million U.S. adults, roughly 15%, said they don’t know how to swim¹³. CDC, reporting those results in 2024, counted more than 4,500 drowning deaths a year from 2020 to 2022²¹³.

Swimming still deserves its reputation as one of the kindest workouts for the body. This guide covers what water does to you, what the health research shows, how adults learn, an eight-week plan from water walking to laps, and the safety rules for pools and open water.

Water carries your weight and changes how your heart works

Water holds you up. In a 2009 review in the journal PM&R, physician Bruce Becker reported that water up to your navel takes about half your body weight off your legs. At the bottom of your breastbone, the load drops by 60% or more³.

That’s why water is a common choice for people whose knees, hips or feet complain on land, since you can move through a full range of motion without the pounding.

Water also squeezes, and its pressure pushes blood from your legs toward your chest. At neck depth, about 0.7 liters more blood shifts into your chest, and your heart holds 27% to 30% more blood³. Each beat moves more blood, so your heart can do the same job with fewer beats.

That has a practical effect: for the same oxygen use, heart rate in water runs about 10 beats a minute lower than on land³. A heart-rate target from a land workout or a watch formula can push you harder than you meant to go, so judge your effort by feel instead.

Breathing takes more work, too, rising about 60% at rest when you’re in water up to your neck³. That may be one reason new swimmers feel winded so quickly.

Finally, water pulls heat from your body about 25 times faster than air does³. That feels good in a warm pool and turns dangerous in a cold lake.

One note on the source: Becker’s review lists a disclosure involving the National Swimming Pool Foundation, and the reprint doesn’t spell out what it covers³. The measurements he summarizes come from many earlier studies.

Swimmers live longer in big surveys, and healthier people may simply swim more

In 2016, a team led by Pekka Oja and Emmanuel Stamatakis pooled health surveys of 80,306 adults in England and Scotland⁴. The average participant was 52. The researchers then checked who died over the following years.

After adjusting for other differences they could measure, people who reported swimming had a 28% lower risk of dying from any cause. Their risk of dying from heart and blood vessel disease was 41% lower⁴.

Those are striking numbers, but this is an observational study, meaning researchers watched what people already did rather than assigning anyone to swim.

People who swim may differ in ways that protect their health, such as income, pool access or fewer illnesses to begin with. Statistics can adjust for some of those differences, not all of them.

When the study came out, outside experts named other limits⁵. Cambridge statistician David Spiegelhalter pointed to reverse causation: people who are getting sick may stop playing sports. Sheffield cardiologist Tim Chico noted that activity was measured by a single questionnaire⁵.

Trials give firmer answers, and one small trial is encouraging. In a 2012 study in The American Journal of Cardiology, 43 inactive adults over 50 had mildly high blood pressure and took no blood pressure medicine⁶. They were randomly assigned to 12 weeks of swimming or to relaxation and stretching.

The swimmers’ systolic pressure, the top number, fell from 131 to 122 mm Hg. Their neck arteries became 21% more flexible⁶. Their body weight didn’t change, so weight loss doesn’t explain the drop. The relaxation group showed no significant changes⁶.

The trial was small and short, and the pages we could open didn’t name its funders. Treat it as a promising sign, not proof.

For sore knees and hips, warm-water exercise helps a little

Osteoarthritis, the wear-and-tear form of arthritis, can make moving on land painful, and water offers another way in.

In 2016, Cochrane reviewers pooled 13 randomized trials with 1,190 people who had knee or hip osteoarthritis⁷. Three in four were women, and the average age was 68. The programs ran about 12 weeks in water warmed to roughly 90 to 97 degrees Fahrenheit⁷.

On a 0-to-100 pain scale where lower is better, people in water exercise ended at 41 and comparison groups at 46. Disability scores followed the same pattern, 39 versus 44. Quality of life scored 57 versus 50⁷.

Five points is a small change, and the reviewers rated the evidence moderate in certainty and judged the gains small but meaningful to patients⁷. The review looked only at results right after the programs ended, not over the longer term. No serious harms were reported⁷.

These trials tested exercise in warm pools, not lap swimming, so you don’t need a perfect stroke to benefit.

For readers who would rather try movement before adding pills, this is the kind of evidence worth having. The benefit is modest, and the risk is low. Water exercise can work alongside the care your clinician recommends, not in place of it.

What the evidence shows, rated

We rate health outcomes, not just fitness changes.

Claim	What studies found	Rating
Warm-water exercise brings small, short-term relief for knee and hip arthritis	13 randomized trials; small, short-term gains in pain, function and quality of life7	Strong evidence
Swimming lowers blood pressure	One 12-week randomized trial in 43 adults over 506	Promising but early
Swimming helps you live longer	Lower death rates in one large observational study; no long-term trials45	Promising but early
Water takes weight off your joints	Water carries about half your weight at navel depth, more at chest depth3	Strong evidence (measured physics)
Land heart-rate zones work the same in water	Heart rate runs about 10 beats lower for the same effort3	Evidence says no

Many adults who say they can swim lack the basics, and you can learn at any age

The Red Cross counts five skills as basic¹. You should be able to get into water over your head, come back up, and float or tread water for one minute. Then you turn in a full circle to find the way out, swim 25 yards, and climb out.

In the 2014 survey, 57% of men but only 36% of women said they had all five¹. Nearly half of adults, 46%, said they had at some point feared they might drown¹.

The 2023 federal survey shows who missed out on lessons. Overall, 55% of adults never took one, including 72% of Hispanic adults and 63% of Black adults². About 37% of Black adults say they don’t know how to swim, compared with 15% of all adults². CDC calls for affordable lessons and for building or reviving pools in places that lack them².

Yet only 2% of adults in the Red Cross survey planned to take lessons that summer¹. Adult classes exist, and CDC points to the Red Cross, the YMCA, swim schools and USA Swimming as places to find them².

A few tips make a first class easier:

• Ask for an adult-only or adult-beginner class, so you aren’t learning beside a row of 6-year-olds.
• Tell the instructor if you’re afraid of the water. Fear is common, and good teachers start with floating and breathing.
• Wear goggles. Seeing underwater takes away a lot of the panic.
• Practice the five skills only with a lifeguard or instructor watching, in a spot where you can reach the wall.

An eight-week plan: from water walking to laps

Check with a clinician first if you have heart, kidney or metabolic disease such as diabetes, or if you notice warning signs. Widely used screening guidance from the American College of Sports Medicine (ACSM) says inactive people without those conditions or symptoms don’t need a doctor’s clearance before they start⁸. Starting gently, as the plan below does, is still wise.

Warning signs include chest discomfort, unusual breathlessness, dizziness or fainting with exercise, a pounding or irregular heartbeat, ankle swelling and leg cramps on short walks⁹. If any of these appear, stop and get checked before you go on⁸. Because immersion sends extra blood to your heart³, people with known heart disease have one more reason to ask first.

Judge effort by feel. Use a 0-to-10 scale where 0 is resting and 10 is your hardest. Start around 3 to 4, where you could chat easily. Build to 5 to 6, where you breathe harder but can still say a full sentence when you stop at the wall.

This plan is our own design, built from the basics above, not a tested program. Do two or three sessions a week, in a pool with a lifeguard.

Weeks	Each session	Effort (0–10)
1–2	15 minutes of water walking in waist- to chest-deep water: forward, backward and sideways. Add 5 minutes of arm sweeps.	3–4
3–4	10 minutes of water walking. Then hold the wall and kick, 4 rounds of 30 seconds. Practice floating on your back with a foam noodle, 3 rounds of 20 seconds.	4
5–6	5 minutes of water walking. Then 6 to 8 widths or single lengths with a kickboard or easy stroke, resting 30 to 60 seconds at the wall between each.	4–5
7–8	5 minutes of water walking. Then 8 to 10 lengths of about 25 yards, in sets of one or two, resting 30 seconds between sets. Finish with 5 easy minutes.	5–6

Progression rule: Move to the next stage when the current one feels like a 4 or less for two sessions in a row. Repeat any stage as long as you like.

If arthritis is your main reason for being in the water, you can stay with stages 1 and 2 for good, ideally in a warm pool. That’s close to what the Cochrane trials tested⁷.

Open water adds cold shock, and drowning risk climbs with age

Older adults are not immune to drowning. CDC found that the drowning rate for people 65 to 74 rose 19% in 2022 compared with 2019, and adults 65 and older have the second-highest rate of any age group².

Lakes, rivers and oceans add a danger pools don’t: cold water shock. Washington State Parks describes it as an instant, involuntary reaction to sudden cold, separate from hypothermia¹⁰. You gasp hard, and if your face is underwater, you can breathe in water. Your pulse and blood pressure can jump sharply as well¹⁰.

It doesn’t take ice: the parks agency warns that water in the 70s can still trigger it¹⁰. And because water pulls heat away about 25 times faster than air³, being a strong swimmer doesn’t protect you for long.

Cold-water safety guides teach a “1-10-1” rule¹⁰. You have about one minute to get your breathing under control, about 10 minutes of useful movement to get yourself out, and about an hour before cold could knock you unconscious.

• First minute: Don’t try to swim. Lie back and float with your face out of the water while your breathing settles¹⁰.
• Wear a life jacket in open water and on boats. The parks agency calls it the single most important protection¹⁰.
• Skip alcohol before and during swimming or boating, as CDC advises².

If you’re drawn to cold dips on purpose, see our article on cold plunges. That’s a different practice from falling into cold water by surprise.

Chlorine doesn’t kill every pool germ fast

It’s easy to assume a chlorinated pool is germ-free, but CDC’s outbreak data tell a more complicated story.

From 2015 to 2019, health departments reported 208 outbreaks tied to pools, hot tubs and water playgrounds¹¹. They caused at least 3,646 illnesses, 286 hospital stays and 13 deaths¹¹.

The leading cause was Cryptosporidium, or Crypto, a parasite that causes diarrhea. It accounted for 2,492 of the cases with a confirmed cause¹¹. Crypto can survive more than 7 days in properly chlorinated water¹¹. All 13 deaths came from outbreaks of Legionnaires’ disease, a pneumonia caused by bacteria¹¹.

A third of the outbreaks were linked to hotels, motels, lodges, inns or resorts¹¹, so vacation pools deserve the same checks as your local one.

CDC’s prevention advice, updated in 2025, is simple: stay out if you have diarrhea, and after a Crypto diagnosis, wait two weeks after the diarrhea fully stops¹². Shower for about a minute before you swim, and don’t swallow the water¹². People with weakened immune systems should talk with a clinician before swimming¹².

Questions readers ask

The bottom line

Swimming and water exercise give you a way to move hard with little pounding on your joints. The evidence is solid for small arthritis gains and encouraging for blood pressure and a longer life, though healthier people may simply be more likely to swim.

The first step for many adults is skill, not fitness. Make sure you can do the five basic water skills, learn in a supervised pool, keep germs out of the water, and treat cold open water with respect.

Related reading

• A cold plunge eases soreness but can shrink your muscle gains
• Wellness advice is written for an average person who doesn’t exist
• Some healthy habits clash with your medicines, so check these goals first
• Cycling’s health payoff outweighs city smog, so traffic is the risk to manage

Sources

1. American Red Cross. “New National Survey Finds More than Half of All Americans Can’t Swim or Perform Basic Swim Safety Skills.” Press release, May 20, 2014. redcross.org
2. Centers for Disease Control and Prevention. “Vital Signs: Drowning Deaths Increase.” Updated June 18, 2024. cdc.gov
3. Becker BE. “Aquatic Therapy: Scientific Foundations and Clinical Rehabilitation Applications.” PM&R, 2009;1(9):859–872. doi:10.1016/j.pmrj.2009.05.017. Reprint: ewacmedical.com
4. Oja P, Kelly P, Pedisic Z, et al. “Associations of specific types of sports and exercise with all-cause and cardiovascular-disease mortality: a cohort study of 80 306 British adults.” British Journal of Sports Medicine, 2017;51(10):812–817. research-information.bris.ac.uk
5. Science Media Centre. “Expert reaction to study reporting associations between different types of sports and mortality.” November 29, 2016. sciencemediacentre.org
6. American College of Cardiology. Journal scan of “Effects of Swimming Training on Blood Pressure and Vascular Function in Adults >50 Years of Age.” American Journal of Cardiology, 2012;109(7):1005–1010. acc.org
7. Bartels EM, Juhl CB, Christensen R, et al. “Aquatic exercise for the treatment of knee and hip osteoarthritis.” Cochrane Database of Systematic Reviews, 2016, Issue 3, CD005523. cochrane.org
8. Green DJ. “New Preparticipation Guidelines Remove Barriers to Exercise.” American Council on Exercise, February 2018 (summarizing ACSM’s Guidelines for Exercise Testing and Prescription, 10th ed.). acefitness.org
9. Leeds Beckett University, Carnegie School of Sport. “Health screening guidance” (based on ACSM, 10th ed.). Version of July 2020. Www.Leedsbeckett.Ac.Uk
10. Washington State Parks. “Cold water shock: What it is and how to protect yourself.” March 10, 2026. parks.wa.gov
11. Hlavsa MC, Aluko SK, Miller AD, et al. “Outbreaks Associated with Treated Recreational Water — United States, 2015–2019.” MMWR, 2021;70(20):733–738. cdc.gov
12. Centers for Disease Control and Prevention. “Preventing Swimming-related Illnesses.” Updated June 6, 2025. cdc.gov
13. Clemens T, Moreland B, Mack KA, et al. “Vital Signs: Drowning Death Rates, Self-Reported Swimming Skill, Swimming Lesson Participation, and Recreational Water Exposure — United States, 2019–2023.” MMWR, 2024;73(20):467–473. cdc.gov