This new report was produced by the Swimming and Health Commission and the Commission was established by an organization called Swim England to identify evidence for the health benefits of swimming and to promote future research in this area. It is a rather long, detailed and well-referenced document called The Health and Wellbeing Benefits of Swimming which I encourage you to go check out but I will attempt to highlight here what I found to be the most interesting takeaways from the study.
Let's Dive In!
Right off the top, it is estimated in this study that those who swim for recreational or competitive purposes are eight times more likely to meet general physical activity guidelines (which includes being active for at least 150 minutes per week).
Long-term swim training can also improve cardiorespiratory fitness or endurance in certain subsets of the population as well, such as healthy pre-pubertal girls and adults, women during pregnancy, children with asthma, and adults with osteoarthritis (which is a rather common condition affecting joints, causing pain and stiffness). We’ll get into each of those a little later but you can see how far into the deep end the researchers went.
The study states that it is clear from the evidence that being able to swim and swimming regularly can have considerable health and wellbeing benefits. Research has identified that any amount of swimming participation compared to those who engaged in none, was associated with a 28% and 41% reduction in all cause and cardiovascular disease cause mortality respectively. The striking evidence of where swimming has afforded significantly improved health, quality of life and a sense of community are additionally impressive.
How Does Swimming Boost Health?
Most studies exploring the relationship between physical activity and physical health have generally focused on activities such as walking, cycling, running or aerobics classes despite the fact that swimming and other forms of aquatic exercise (aqua-jogging and aqua-aerobics for example) are some of the most popular choices for meeting physical activity recommendations – for their aerobic, strength and balance elements. This is often attributed to the fact that exercise in an aquatic environment confers many benefits – minimized weight-bearing stress, a humid environment and a decreased heat load (unless you swim in one of those oddly warm Therapeutic Pools that they had in my neighborhood as a kid… it was hard distinguish my sweat from the pool water).
The study compared the health aspects of swimming with alternative forms of aerobic exercise, and sedentary behavior. Participants included 10,518 women and 35,185 men aged 20- 88 years old. Now as with most studies of this type, the majority were Caucasian and of middle/upper socio-economic status, which is something I know many universities and research groups are trying to correct seeing as this is not a great way to draw sweeping conclusions over our much more diverse global population.
Screening included a formal subjective and objective history, anthropometric measurements, blood tests and a graded exercise test. Participants were categorized as ‘sedentary’ (no participation in activity over the previous three months), ‘walkers’ (primarily engaged in run/walk/jog at a pace ≥15min/mile), ‘runners’ (primarily engaged in run/walk/jog at a pace ≤15min/ mile), and ‘swimmers’ (exclusively engaged in swimming activity).
The results were pretty darn clear that all types of physical activity produced demonstrable health benefits in comparison to a sedentary lifestyle but of all the groups, swimming and running achieved the highest treadmill test duration and maximal metabolic equivalent levels. Although interestingly enough, the Body Mass Index (BMI) of swimmers was significantly higher than that of runners.
Higher BMI?
I deviated from this particular study for a few minutes to find out why BMI might be higher in a swimmer despite the fact that elite swimmers typically undertake 4000-20,000 m per day in their training, which burns thousands of calories. Two theories seem to be popular.
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It has been suggested that swimming doesn't cause the appetite drop that accompanies heavy running or cycling training, so swimmers may overcompensate for the energy they have just burned. Some research goes on to suggest that this is due to the cool temperatures in which swimmers train.
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Swimmers are less active outside their training sessions because they are so tired from the hours spent training that they sleep, sit or otherwise avoid any real energy expenditure outside their sessions. Which to me seems less likely that reason number one.
Also, when a sport is performed in the water, fat provides more buoyancy than muscle mass. This allows swimmers who have a higher percentage of fat to float more readily in the water. Instead of having to use energy to stay horizontal, the athlete can focus on their stroke and kick to move them forward. Swimmers with a lot of muscle mass may have more strength, but it ends up being wasted on the mechanics of trying to staying high in the water.
There does not seem to be one clear reason for this but if you watch footage from the Olympics you likely noticed that each and every sport has a particular body type, and swimming leans toward the rounded shoulders and smooth curves which are more biomechanically useful in the water than bony angles. Correlation? Causation? You choose.
Valuable Lifetime Activity
But back to the study, where the authors conclude that “swimming constitutes a valuable lifetime activity” and appears to produce healthy levels of cardiorespiratory fitness and is a viable alternative to other forms of exercise.
This is further supported by the results of a prospective study of the health effects of physical activity and fitness in 40,547 men which concluded that swimmers had lower mortality rates than those who were sedentary, walkers or runners even after controlling for age, body mass index, smoking/alcohol and family history. Similar results have been demonstrated by a cohort study of over 80,000 British adults where swimming participation was associated with a significantly reduced risk of all-cause mortality of 28%, and cardiovascular disease mortality of 41%.
Is It More Than Just Exercise?
Clearly, heading to your local pool offers a great opportunity for aerobic activity, however, the specific interaction between physiological and hydrodynamic effects of being immersed in water are also super interesting and might be lending additional advantages.
The study listed five factors that the role of water might be playing in the positive results being found.
Density - The human body density is slightly less than that of water, therefore the volume of water displaced weighs more than the immersed body resulting in an upward force equal to the volume of water displaced. You can think of this as being like a compression stocking for the part of your body that is submerged.
Hydrostatic Pressure - Pressure is proportional to the liquid density and the immersion depth (which means the deeper you go the more pressure there is). Hydrostatic pressure results in plastic deformation of the body (your body gets squeezed), shifting blood towards the heart, raising right atrial pressure, and causing a cephalad displacement of the diaphragm (cephalad means “toward the head”). You can think of this as a turbo boost which reduces the work of breathing associated with expiration, your heart’s preload, its cardiac output, and the body’s venous blood flow.
Buoyancy - Immersion to the xyphoid (a small bump of cartilage in the sternum) off loads bodyweight by 60% or more, and to to C7 (near the bottom of your cervical spine) by 75% or more. Buoyancy results in ‘off loading’ of peripheral and spinal joints. You can think of this as greatly reduced gravity and impact.
Viscosity - Limb movement in water is subject to drag force and turbulence. Viscous resistance offers opportunities for strength training via the principle of loading. You can think of this as the water being like a resistance band that’s been attached to all your limbs, turning all your movements into a strength training regime.
Thermodynamics - Water may be used over a wide range of temperatures due to its heat capacity and conduction properties. Many public pools operate at 27-29°C, although sometimes increased to 33.5-35.5°C for ‘therapeutic’ sessions. You can think of this as being like a mild icing for your sore muscles or a mild hot tub for again your sore muscles. You can find out more about cold water uses in a previous Get-Fit Guy post and you can also imagine how much harder you would be able to workout when the water is adding a cooling benefit that would usually be relegated to your perspiration and respiration.
After examining the effects of swimming on cardiovascular and cardiometabolic health, pulmonary health, musculoskeletal (MSK) health, neurological health, health for people with disability, health for the frail elderly, health for women (specifically post-menopausal women with osteoporosis, pregnant women and women with breast cancer) the study summary stated that the unique nature of the aquatic environment as a medium for exercise can layer on a large number of specific advantages, especially as compared to land-based exercise.
Which makes sense now that we see it as an exercise environment that offers reduced weight-bearing stress, higher humidity levels, decreased heat load and a greater margin of therapeutic safety in terms of falls-risk, swimming and aquatic exercise can be seen to safely and effectively meet the needs of a wide-range of individuals, in both the treatment and prevention of physical health issues.
In Chapter 2 (of the 7 chapter study), the researchers looked at very specific subsets of the population to see how swimming benefited them.
They Began with Children
A recent study in a large city in England investigated the impact of the local authority providing free swimming passes to 1,011 young disadvantaged children in a pre and post-test study. The authors found that providing free swimming passes helped increase self-report physical activity levels among children, with the most notable improvements seen among those who were sedentary or insufficiently active at baseline.
Another study called: Aerobic exercise interacts with neurotrophic factors to predict cognitive functioning in adolescents recruited adolescents who had in the past two months completed some or all of the following: intensive rowing, swimming and triathlon training and compared their neurocognitive performance versus age and sex matched controls that were not engaging in regular exercise. The authors found that frequent exercisers (which could have been any of the activities I just listed) had better cognitive performance, which was attributed to increases in brain derived neurotrophic factor (BDNF). However, it was not possible to confirm or refute whether the differences in cognition among the “swimmers” and the controls were actually due to swimming or simply getting more exercise in general since we know exercise in general makes us smart!
In 2013, a study into the cognitive benefits of swimming lessons for children, reported that children participating in regular swimming lessons achieved a range of developmental milestones much earlier than the wider population regardless of socio-economic background or gender. Swimmers were between six and twelve months ahead of the norm in physical skills, cognitive skills, mathematics, language development, counting and ability to follow instructions. The reason this is important is that these areas are considered to be the key skills used in “formal education contexts” which, the authors believe, may give swimmers a “considerable advantage” as they start their academic studies.
What About Adults?
A survey study among 200 females aged 40-60 years across five cities in Korea suggested that participation in swimming was associated with improved life satisfaction, mental health and self-perception of health.
Another study of 300 adults reported that participating in swimming lessons was associated with better self-rated health, including better psychological health, reduced levels of stress and lower levels of disability.
And Older Adults?
One study found that regular older swimmers who reported swimming between two and five times a week over a period on average of 2.5 years, had significantly better executive function on three tasks, compared to sedentary older adults of similar age and gender who did not swim.
A recent Cochrane review found some evidence that aquatic exercise improved anxiety symptoms and sleep among people with fibromyalgia.
Another Cochrane review suggested that aquatic exercise has a small improvement on quality of life among people with hip or knee osteoarthritis and low back pain.
And others?
I am not going to get into all the categories in the study (like I said before, it is comprehensive) but they went on to look at swimming and its benefits for other medical conditions such as:
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Pregnancy
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Cancer
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Mental health
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Dementia and cognitive decline
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Cerebral palsy
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Learning disabilities
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Autism
Concluding that “There is growing recognition that exercise can cross many boundaries and meet the wellbeing needs of the population from the cradle to grave.”
Off to the Pool!
Many of us have fond memories of going to swimming lessons as children, playing in the community outdoor pool on a hot summer day, splashing around in a lake or the ocean on vacation, and perhaps even competing in some local, provincial or national swim meets. Who knew all the good we were doing for our wellbeing while having all that fun and forever associating the bleachy, acrid smell of chlorine with the happy, nervous moments of seeing and being seen in your bathing suit.
I for one am sold and I am now headed to the pool to do some drills, practice my flip turns and reap all the benefits that swimming has to offer. Who’s with me?
If you are a lifelong swim fan like me or have questions about how to incorporate swimming into your routine, head over to http://ift.tt/1xq4tPg or http://twitter.com/getfitguy. Also don't forget to subscribe to the Get-Fit Guy podcast on Apple Podcasts, Stitcher, SoundCloud, Spotify, Google Play or via RSS.
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