The fountain of youth hasn’t been found — but swimming may come close

Aug 11, 2021 / Seena Mathew PhD


It’s no secret that aerobic exercise can help stave off some of the ravages of aging. But a growing body of research suggests that swimming might provide a unique boost to brain health.

Regular swimming has been shown to improve memorycognitive functionimmune response and mood. Swimming may also help repair damage from stress and forge new neural connections in the brain.

If more adults recognized the cognitive and mental health benefits of swimming, they’d jump in the pool alongside their kids.

But scientists are still trying to unravel how and why swimming, in particular, produces these brain-enhancing effects.

As a neurobiologist trained in brain physiology, a fitness enthusiast and a mom, I spend hours at the local pool during the summer. It’s not unusual to see children splashing and swimming while their parents sunbathe — and I’ve been one of those parents plenty of times. But if more adults recognized the cognitive and mental health benefits of swimming, they might be more inclined to jump in the pool alongside their kids.

Creating new and improved brain cells and connections

Until the 1960s, scientists believed that the number of neurons and synaptic connections in the human brain were finite and that, once damaged, these brain cells could not be replaced. But that idea was debunked as researchers began to see ample evidence for the birth of neurons, or neurogenesis, in adult brains of humans and other animals.

Now, there is clear evidence that aerobic exercise can contribute to neurogenesis and play a key role in helping to reverse or repair damage to neurons and their connections in both mammals and fish.

Research shows that one of the key ways these changes occur in response to exercise is through increased levels of a protein called brain-derived neurotrophic factor. The neural plasticity — or ability of the brain to change — that this protein stimulates has been shown to boost cognitive function, including learning and memory.

Aerobic exercise also promotes the release of  neurotransmitters, including serotonin, which — when present at increased levels — is known to reduce depression and anxiety and improve mood.

Studies in people have found a strong relationship between concentrations of brain-derived neurotrophic factor circulating in the brain and an increase in the size of the hippocampus, the brain region responsible for learning and memory. Increased levels of brain-derived neurotrophic factor have also been shown to sharpen cognitive performance and to help reduce anxiety and depression. In contrast, researchers have observed mood disorders in patients with lower concentrations of brain-derived neurotrophic factor.

Aerobic exercise also promotes the release of specific chemical messengers called neurotransmitters. One of these is serotonin, which — when present at increased levels — is known to reduce depression and anxiety and improve mood.

In studies in fish, scientists have observed changes in genes responsible for increasing brain-derived neurotrophic factor levels as well as enhanced development of the dendritic spines — protrusions on the dendrites, or elongated portions of nerve cells – after eight weeks of exercise compared with controls.

This complements studies in mammals where brain-derived neurotrophic factor is known to increase neuronal spine density. These changes have been shown to contribute to improved memorymood and enhanced cognition in mammals. The greater spine density helps neurons build new connections and send more signals to other nerve cells. With the repetition of signals, connections can become stronger.

But what’s special about swimming?

Researchers don’t yet know what swimming’s secret sauce might be. But they’re getting closer to understanding it.

Swimming has long been recognized for its cardiovascular benefits. Because swimming involves all of the major muscle groups, the heart has to work hard, which increases blood flow throughout the body. This leads to the creation of new blood vessels, a process called angiogenesis. The greater blood flow can also lead to a large release of endorphins — hormones that act as a natural pain reducer throughout the body. This surge brings about the sense of euphoria that often follows exercise.

Most of the research to understand how swimming affects the brain has been done in rats. Rats are a good lab model because of their genetic and anatomic similarity to humans.

In one study in rats, swimming was shown to stimulate brain pathways that suppress inflammation in the hippocampus and inhibit apoptosis, or cell death. The study also showed that swimming can help support neuron survival and reduce the cognitive impacts of aging. Although researchers do not yet have a way to visualize apoptosis and neuronal survival in people, they do observe similar cognitive outcomes.

 In one limited study looking at the impact of swimming on mental acuity in the elderly, researchers concluded that the swimmers had improved mental speed and attention compared with non-swimmers. 

One of the more enticing questions is how, specifically, swimming enhances short- and long-term memory. To pinpoint how long the beneficial effects may last, researchers trained rats to swim for 60 minutes daily for five days per week. The team then tested the rats’ memory by having them swim through a radial arm water maze containing six arms, including one with a hidden platform.

Rats got six attempts to swim freely and find the hidden platform. After just seven days of swim training, researchers saw improvements in both short- and long-term memories, based on a reduction in the errors rats made each day. The researchers suggested that this boost in cognitive function could provide a basis for using swimming as a way to repair learning and memory damage caused by neuropsychiatric diseases in humans.

Although the leap from studies in rats to humans is substantial, research in people is producing similar results that suggest a clear cognitive benefit from swimming across all ages. For instance, in one study looking at the impact of swimming on mental acuity in the elderly, researchers concluded that swimmers had improved mental speed and attention compared with non-swimmers.

However, this study is limited in its research design, since participants were not randomized and thus those who were swimmers prior to the study may have had an unfair edge.

Another study compared cognition between land-based athletes and swimmers in the young adult age range. While water immersion itself did not make a difference, the researchers found that 20 minutes of moderate-intensity breaststroke swimming improved cognitive function in both groups.

For centuries, people have been in search of a fountain of youth. Swimming just might be the closest we can get.

Kids can get a boost from swimming too

The brain-enhancing benefits from swimming appear to also boost learning in children.

Another research group recently looked at the link between physical activity and how children learn new vocabulary words. Researchers taught children age 6-12 the names of unfamiliar objects. Then they tested their accuracy at recognizing those words after doing three activities: coloring (resting activity), swimming (aerobic activity) and a CrossFit-like exercise (anaerobic activity) for three minutes.

They found that children’s accuracy was much higher for words learned following swimming compared with coloring and CrossFit, which resulted in the same level of recall. This shows a clear cognitive benefit from swimming versus anaerobic exercise, though the study does not compare swimming with other aerobic exercises. These findings imply that swimming for even short periods of time is highly beneficial to young, developing brains.

The details of the time or laps required, the style of swim and what cognitive adaptations and pathways are activated by swimming — these are still being worked out. But neuroscientists are getting much closer to putting all the clues together. For centuries, people have been in search of a fountain of youth. Swimming just might be the closest we can get.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

How fast is the speed of thought? Watch this TED-Ed lesson to find out: 

About the author

Seena Mathew PhD is an Assistant Professor of Biology at The University of Mary Hardin-Baylor (UMHB). She earned her Bachelor’s degree in Neuroscience from Kenyon College and her doctorate in Neurobiology from the University of Alabama at Birmingham. She later also earned a Masters in Public Health. Prior to her time at UMHB, she was a lecturer at The University of Texas at Austin and Program Director for the Health Science and Public Health programs at South University. Her research interests are a blend of public health and neuroscience with a focus on learning and memory.

Swimming doesn’t only burn calories. It is also low impact.

Water is about 800 times denser than air. This means you can work harder and burn more calories in a pool.

Swimming can support up to 90% of the body’s weight in the water, creating a safer exercise environment for people with injuries.

The pressure of water means you can work to the same intensity as on land but with a heart rate of up to 20bpm lower.

In 15 minutes;

Bearing in mind walking at 3mph (4.8kph) burns 50Kcal

Butterfly burns 202Kcal where running at 8mph (13kph) burns 203Kcal

Breaststroke burns 184Kcal where running at 6mph (9.7kph or a 10min mile) burns 150Kcal

Backstroke burns 129Kcal where cycling at 12/14mph (21kph) burns 120Kcal

Front crawl (fast) burns 202Kcal

Front crawl (slow) burns 129Kcal

To compare all the different strokes and with variable times check out the Swim England Calorie Cruncher…just click on this link


Some Sugar Facts

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Just how bad is sugar for our health?


In the last year or two we have been bombarded with information and articles in the news about the detrimental effects of sugar and how it is responsible for the current rising obesity levels across the country. So just how bad is sugar?

Many of us think that having a little sugar here and there is not a problem, we will burn it off later or eat something healthy for dinner to compensate. The truth is, every bit of sugar you are having is detrimental to your health, and once you have consumed it, the damage is already done.

Too much sugar triggers weight gain

Sugar is actually incredibly hard to burn off through exercise, and in fact, it can often lead to weight gain. Eating sugar is basically the same as asking your body to begin storing fat. When you eat a sugary snack, like a doughnut or a chocolate bar, your blood-glucose levels spike which stimulates the release of insulin.

Insulin is a hormone which allows the body to process sugar (glucose). All of the cells in your body need glucose for energy and insulin is the key to allow the cells to use glucose, as it cannot be directly absorbed from the bloodstream.

When you have a spike in blood sugar levels which is more than your cells need for energy, insulin also helps to store the excess sugar, but in the process it also instructs your body to store fat too.

Excess sugar can cause Type 2 Diabetes

If your body is working overtime to process excess sugar, your hormonal system which tells your pancreas to produce insulin can become desensitised and your pancreas overworked, leading to Type 2 Diabetes.

At the same time that all this is going on, high levels of blood sugar also lead to Glycation. This is where glucose starts to bind with other fat and protein molecules, not just in your food, but also those within your body.

Internally this can impair and damage all kinds of molecular function, accelerate the ageing process, damage skin, overwork organs, weaken joints and muscles and increase fat retention.

Should we cut out sugar altogether?

Natural cane sugar, the stuff you have in your tea and coffee, is not a major problem. Having a scoop in a cup of tea is not going to destroy your body, but simple sugars contain no beneficial nutrients at all and make us fat through excess and empty calories.

The real issue lies within the everyday food products which we consume every day and don’t even think about. Many people’s diets are made up of huge amounts of fizzy drinks, cakes, biscuits, sugary cereals, chocolates and crisps. People often consume 40-50 grams of sugar in one sitting without even realising it.

To put this in perspective, it’s not just your sugary snacks. During digestion, one slice of white bread has the equivalent amount of glucose as four tablespoons of natural cane sugar. In fact, if you drink a can of coke, have a sandwich, a yoghurt and a cake for lunch, you will have consumed over 60 grams of sugar. The recommended daily allowance (RDA) is around 40 grams.

What foods should we avoid?

There are also many foods that are ‘dressed up’ as healthy such as the craze on smoothies and some of these so-called protein milk shakes, all of these can contain a massive 60 – 80 grams of sugar through the high fructose corn syrups that are put into them.

So now you know the impact simple sugars have upon us and our families/children today, the key is to cut out or limit any intake of many of the commonly bought foodstuffs below that are responsible for fat retention, illnesses, ageing, and increased incidences in diabetes, heart disease and cancers.

  • Fizzy sodas

  • Confectionery/Sweets

  • Biscuits/Cookies

  • Cakes/Doughnuts etc

  • Sugary breakfast cereals

  • Concentrated fruit juices

  • Sports drinks (They often have no place in sport anyway and are an advertising gimmick)

  • Ice creams

  • Desserts (including the low fat varieties which are often worse than normal ones)

  • Many low-fat foods (while they are low in fat content, they usually have more sugar to compensate)