Low body fat = warm during swim?

andissandiss Senior Member
edited June 2015 in Beginner Questions

Just looking for tips how to prolong my swims in cold water. Coming from a triathlon background = skinny enough and I don't want to gain weight. Like I last maybe 40-45min in 11-12C so any longer ow swims has been put off. In a wetsuit in the same temp i would last +3hours easily.

To date I've received 3 tips:

Warm feeds

Higher stroke rate

Keep at it and acclimatize

I don't want to go back to wetsuit and a layer of grease is a myth due to the thermal conductivity of fats/oils/greases is in the same range as human tissues.

Is that it? Or Maybe I should just move to Barbados or something!



  • andissandiss Senior Member

    That's a layer of grease on the outside of the skin! ;)

  • phodgeszohophodgeszoho UKSenior Member

    I think the three tips you listed are pretty much it. The only thing I would add to them is "time" i.e. acclimatization takes time.

    I personally found that the third year of swimming through the winter was definitely a tipping point where things seemed to get a lot easier.

    The good news is I do know several swimmers who I would describe as having more of a "triathlon" physique then the traditional open water swimmer physique who have successfully acclimatised and completed cold water marathon swims, so it can be done.

    PS full disclosure - I am not one of the swimmers with a triathlon physique. More of a sponge bob square paints-esque physique... ;-/

  • JenAJenA Charter Member
    edited June 2015

    I encourage time as well. :) I remember my first swim at 60oF (15.5oC) and thinking there was noooooo way this was a reasonable expectation. :-) And now, I've been down to 8oC for 30 minutes in fresh water without shivering.

    I don't think warm feeds are as (physiologically) helpful as some think they are. I actually don't even bother with them anymore. I can't find a good webpage on this topic, but the best comparison I've found is this: say you have a large bucket of water that weighs as much as you do. Let's say:

    • you weigh 100kg (220b) for nice 'round' numbers.

    • the bucket of water (weighing 100kg) is at 37oC (98.6oF).

    • coffee is ideally served at 70-80oC (155-175oF)*.

    • you throw 250ml (1 cup) of coffee, which weighs 0.25 kilo (0.55 pounds) into the bucket

    I'm sure the thermo math isn't as simple as this but if you have 100 'things' worth 37, and 0.25 'things' worth 80, that averages out to 37.1 ((10037+0.2580)/100.25). That's a tenth of a degree increase. I don't know about the rest of you, but I couldn't sling back a cup of hot-hot liquid at an impressive speed, either. I'd be cooling in the water as I drank the hot liquid.

    I'm also thinking that the average 'hot' feed during a swim was heated several hours ago and is coming out of a thermos. Maybe it's 50oC? If so, that averages out to 37.03. Which means that, yeah, it helps, but it seems almost theoretical at that point.

    I have a feeling @Leonard_Jansen could shed some light on the actual math. :)

    It's definitely not straight forward. If you're in warm water, and you drink hot liquid, you could actually trigger a sweat/cooling response: http://www.theglobeandmail.com/life/health-and-fitness/fitness/a-hot-drink-cools-you-faster-than-a-cold-one-myth-or-reality/article4474567/


  • phodgeszohophodgeszoho UKSenior Member

    I would also agree that "hot" feeds may not be a viable "tactical" solution for keeping warm. However, the maths aside, it is also about what you prefer and that may also be about what you psychologically get from the feed as much as what you are physically getting. A sort of "The warmer the feed the warmer I feel" situation.

    The thing to remember though is tepid, warm or hot feeds is probably less important then it being a fast feed. Sitting around stationary for a couple of minutes as apposed to a 5-10 second gulp and go can have a lot more impact on your body temp then the temp of the feed consumed.

  • JimBoucherJimBoucher Senior Member

    Fast feeds are certainly desirable, but I have often seen Channel people do it too quickly and lose half or more of the feed. Fast is only good if you consume all you're supposed to consume. You only leave yourself short on energy if you try to do it too quickly. My advice would always be to make sure you get good at getting it all in without barfing then work on speeding up.

  • swimmer25kswimmer25k Charter Member

    Get some earplugs. Lots of heat is lost there.

  • Leonard_JansenLeonard_Jansen Charter Member

    The math of such an issue probably isn;t that difficult, but I think that there may be a more important issue here. Namely, that the warm liquid doesn't have to warm your entire body; it just has to trigger your body to believe that the core is warmer. That will cause a release of warmer blood to the outer part of the body and the perception will be that you are warmer. This can, of course, bite you in the butt because that blood will potentially dissipate more heat into the water and come back into the core colder. Based on anatomical differences, I'd bet that women would feel a bit less warm by such a tactic, but would also stand less chance of a disastrous drop in temp as the blood circulated back.



    “Moderation is a fatal thing. Nothing succeeds like excess.” - Oscar Wilde

  • wendyv34wendyv34 Vashon, WASenior Member

    Peeing makes me feel warmer.


    It's always a bad hair day when you work at a pool.

  • ColmBreathnachColmBreathnach Charter Member

    Depends on what you call cold and what you call long. You're not making it easy on yourself being skinny though. +1 on earplugs, make a big difference for me. The real key is acclimatisation. Swim regular and often in cold water (3+ times / week) and you will improve.

  • jroyerjroyer Member

    I've been thinking about the warm feed question for a bit and gone back and forth about how much the extra heat physically helps. @JenA 's thermo math is spot on for the water bucket example. If you want to be fancy and include the specific heat capacities of the swimmer (3.5 kJ kg^-1 oC^-1 for humans) and the feed (4.2 kJ kg^-1 oC^-1 for water) you end up with (using the subscripts 's' for swimmer, 'f' for feed)
    but that doesn't really change the numbers in the end.

    However, there are a couple of other things to consider with warm-ish feeds.

    A: A cool (less than body temp) feed would not just fail to provide extra warmth, but also slightly cool a swimmer. If un-warmed feeds are kept at 20 oC (about room temp.), then consuming a 250mL feed would drop the 100 kg swimmer's temperature by 0.04 oC. The net temperature difference (50 oC feed compared to the 20 oC feed) is then 0.07 oC. Still a small number, but not quite as small.

    B: Due to vasoconstriction in blood vessels near the skin and in the extremities to conserve heat in cold water, that extra heat from the hot feed will not spread throughout the full mass of the swimmer but should stay fairly localized in the core (since drinking the feed would deliver the heat pretty much directly to the core). I'm not sure how much a person's mass constitute's the 'core' vs the extremities, but if we assume it only gets spread to 70% of the swimmer's full mass, then the temperature rise would then be 0.05 oC and the net difference compared to a 20 oC feed would increase 0.11 oC.

    C: The cumulative effect from a number of warm feeds could add up to make a difference, especially for a long swim close to a swimmer's cold water tolerance. The difference between normal body temp and the onset of hypothermia is only about 3 oC. If we consider a swimmer in conditions where they nominally could last 10 hours in the water before hypothermia set in and assume a constant rate of core temperature change, then this works out to about 0.3 oC/hour or a 0.15 oC drop between feeds if they fed every 30min. In this case, even just a 0.03 oC boost from a warmish (50 oC) feed would undo a fifth of this loss and a steady stream of warm 50 oC feeds could turn a 10 hour swim into a 12.5 hour swim (assuming everything else is held constant).

    This doesn't account for extra time drinking a warm feed. I don't know how much a swimmer's internal heat production drops when they stop swimming, but my guess is that it is enough that the warm feed can't make up for much of an extra delay during feeding time. I was playing around with a thermometer and my coffee this morning, and found that I could chug 50 oC coffee about as fast as I could with a room temperature drink, but at 60 oC I had to really slow down.

    This result does depend on how the swimmer loses heat during the course of the swim. If the 10 hour swimmer instead keeps a constant core temp at 37 oC for the first 5 hours but then their internal heat production drops and they start to lose 0.6 oC/hour for the last 5 hours, then the warm feeds would have a smaller effect, adding an extra hour instead of 2.5 hours. If the rate of heat loss picks up even more towards the end of a swim, the warm feeds would have even less of an effect.

    I don't know enough about heat loss while swimming to really completely answer this question. If it occurs via a slow, steady drop in core temp over the full course of the swim, then it seems warm feeds could make a pretty big difference. However, if it occurs via a more abrupt decrease in core temp towards the end of a swim, then the warm feeds would make much less of a difference. I could imagine a combination of these two scenarios, where a swimmer slowly cools until their swimming (and heat generation) starts to take a hit, and then things run away a lot faster.

  • andissandiss Senior Member

    Cold and long for me is anything more than a duration of 45min in 12C or less!

  • JenAJenA Charter Member

    jroyer said:

    I was playing around with a thermometer and my coffee this morning, and found that I could chug 50 oC coffee about as fast as I could with a room temperature drink, but at 60 oC I had to really slow down.

    Wow. @jroyer has written a brilliant post that truly advances the discussion, and possibly even the body of knowledge of marathon swimming.

    bows down to @jroyer

    @evmo, @loneswimmer: this is a wonderful example of the value of the forum and the larger community. Together, we are truly stronger. It would be great if the annual awards had categories honouring wonderful posts (I'm thinking about @malinaka's DN analysis as well). Perhaps instead of just a 'like' button, there can be a button for flagging a post as 'best in class' or award-worthy?

  • MikeHMikeH Member

    Surprised this thread doesn't have more mention about the intensity of the swim stroke. I crewed on a world record attempt a few years ago and the swimmer was pretty damn skinny - he was clearly generating heat from his pace (stroke pace, not swim pace - though that was very fast as well).

  • sharkbaitzasharkbaitza LondonMember

    I also think that the placebo effect is very relevant. Cold water swimming (once properly acclimatised) is hugely mental. If you believe you will be warmer with a specific drink etc, unless it is actually physiologically detrimental, then it will work.

  • DanSimonelliDanSimonelli San Diego CASenior Member

    I'll be testing out the theory of warm feeds sometime this weekend.

    I've never used warm feeds (except on a couple long training swims for this swim, which I feel helped), so I think I'll have some decent anecdotal comparisons.

    dpm50[Deleted User]
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