I’m not much of a swimmer, but I want to be.  In 2011 it is a major personal fitness goal to try to swim more frequently. The interesting irony is that I was in the pool and spa industry for about a decade and yet I wasn’t ever a swimmer. Most are not; in fact, health and fitness isn’t very common in the industry at all.  There seems to be more focus on fountains than fitness.

It’s the first day  of summer here the the Northern Hemisphere…to all of the readers in the Southern part of the world, you are in the thermal loading sweet spot right now – enjoy.

My initial thoughts of thermal loading came from a detailed analysis of Michael Phelps and his enormous caloric intake.  I was able to talk to him for a few minutes this fall and finally thank him for the inspiration.

If you google “weight loss and swimming,” you’ll find site after site that indicates swimming is bad for losing weight or that swimmers tend to put on body fat. I’ve done an exhaustive literature review and I am confident that both of these assertions are wrong. Most of the quotes comparing  swimming, running and cycling find their root in an 1987 study by Gwinup (1). In it, he compares the three activities in the absence of caloric restriction or monitoring of any kind.

Essentially this study followed moderately obese women in one of  three activities, walking, stationary bicycle, and swimming over a 6 month period.  This is probably one of the most extensively cited papers I have seen.  The results were that walking and cycling caused a drop in weight and swimmers actually gained.  It is astounding that it’s been 24 years ago and not much more has been completed.

The problem with the study as I see it is they didn’t ask the people to restrict diet in any way. If in fact swimming could result in a greater caloric burn due to the thermal load of the water, couldn’t that explain the increase hunger? If they were not instructed on how to specifically counter this, would that account for the weight gain? This is generally applied to everyone, but wouldn’t someone that is applying swimming as part of a comprehensive diet/exercise program understand they had to keep calories restricted?

It is plausible to expect that the additional drain of energy from the thermal load of the water could cause the body to signal hunger.  Remember, the body regulates heat (energy) not temperature, so we might expect the body to simply turn on the hunger mechanism in response to the energy deficit caused by increased heat drain. Most importantly, might we expect that armed with this knowledge, we could turn off, or resist, this hunger trigger with proper diet and nutrition?

I believe the answer is yes.

Gappmaier (2) had some VERY harsh words in 2006 retort to the oft-cited Gwinup paper. He felt that while the data Gwinup suggested from his study might substantiate the opinion offered, the other labs cited in the paper have never published any data/papers supporting it. Gappmaier’s view was that most of the research on modes of aerobic exercise had gone into the cardiorespiratory changes, not weight loss.  In the end, Gwinup didn’t control the very variable that was necessary to draw his conclusions, nevertheless, it has been cited over and over for the last 24 years.

Gappmaier found that with similar frequency, duration, and intensity, swimming results are comparable in terms of weight loss. This parity is good news, but of course it likely  is based on a relatively warm and  consistent water temperature and that is where I think the big opportunities to boost the results reside going forward.

In the last year, I really wanted to find a better way to thermal load in the summer. As well, I wanted to know exactly what the truth is concerning water thermal conductivity and the Human body’s loss of thermal energy (calories). There is no doubt it happens, but there is a question of rate. A somewhat exhaustive review of the literature on the thermoregulatory side found that the simple one dimensional math model I outlined two years ago gave a pretty good fit to actual Human data of the 50s & 60s.

This data was collected to assess macronutrient requirements of military personnel in a cold stress environment; ironically they were studies on how to keep weight on, not lose it.  I know it works, but what are the best methods and how quickly can one lose?

I’ve talked with MANY people following both the TEDMED talk and 4HB and I am astonished at just how much fear we have of cold as a society. In fact, the fear is so great that people often interpret “cool” as cold and begin to bundle at what was a very comfortable room temperature just a few years ago.

Over that last 2 months I have been putting in a new lab and looking at methods to better assess my own progress. Taking one for the “Team” out there, I put about 12 lbs on and want to take it off (with interest) using a solid diet/nutrition plan and swimming. I now have the capability to go down to 45F/7C water temperature for swimming in a swim spa…we’ll see how brave I get.

What I know for sure is that there are studies that seem to verify increased hunger associated with swimming. All of the other references you see, in one way or another, lead back to Gwinup 87.  The vast majority don’t control diet at the same time and suggest that increase hunger makes swimming a futile process for weight loss.

I am not buying it.

I have spoken to so many ex-swimmers that rave about weight loss when getting back into the water. The thermal models say it should work. Most importantly, swimming is probably one the very few physical activities that one can do for a lifetime. You can start at any age or level of fitness and if it IS hot and sticky, it’s a fantastic way to relax.

I still need your help in part of this. I am going to begin collecting data in the next few weeks. Part of what I really need to add to all of the current equipment is a thermal imager.  Be sure to click the voting widget up and to the right and I’ll be sending out requests soon in attempts to get this funded.

So, if you are a swimmer, get your suit on and dive in…even BETTER if you are a swimmer going into winter in the southern hemisphere >grin<. I’ll be subjecting myself to even more extreme self-experiments over the coming months and will report back what I learn.

If you haven’t learned to swim- I feel your pain. I too had an incredibly difficult time getting instruction as an adult. I wasn’t afraid of water (once an avid scuba diver), just didn’t know how to “swim laps;” thanks goes out to Al Bayhi @ iSport.com. If you are in the Bay-area, this guy is THE best.

After much personal study of the Total Immersion techniques, as Tim describes in 4HB, I was able to move from zero ability to swimming comfortably over a 5 day period, 3 hours of instruction a day. It was sort of a brutal immersion, but I REALLY learned a lot. From the aches and pains it is clear to me that I exerted a lot of physical energy during the process.

Swimmin is a great compliment to whatever exercise/diet program you are doing, so get into the swim of things and shed some unwanted body fat.

1.  Gwinup, G. (1987). Weight loss without dietary restriction: Efficacy of different forms of aerobic exercise. American Journal of Sports Medicine, 15, 275-279

2. Gappmaier E, Lake W, Nelson AG, Fisher AG.  Aerobic exercise in water versus walking on land: effects on indices of fat reduction and weight loss of obese women The Journal of Sports Medicine and Physical Fitness 2006, 46:564-569