Testing during a Marathon Swim Event. Lacate/Glucose and HR

jheynesjheynes Member
edited June 2014 in General Discussion
What is the opinion(s) about lactate/glucose testing during an actual marathon solo swim?
A. Does this violate the Rules of Marathon swimming? ( because of having to do blood draw from finger or ear of swimmer and being touched by another person)
B. What value does it have if there is no: 1.baseline before training, 2.none done during training months, 3.only want to do it on event day?

C. Does wearing HR monitor strap with someone else (kayaker) having HR watch on to monitor violate rules?
D. Same and question part B?

thanks for any and all opinions


  • loneswimmerloneswimmer IrelandCharter Member
    Well, for the first question, forum members have had blood tested for insulin levels due to Type 1 diabetes. Once the swimmer isn't supported there's no issue. I assume the yoke used to extract blood is something like the thingamajig used to test iron levels, taking a tiny amount quickly.

    Second question, it looks like you answered it yourself. Any measurement of anything is meaningless without a baseline or a context.

    Third question, probably not, especially if it's for medical purposes. Falls into the Frankenwatch debate, so others may disagree..

    Fourth question, same answer as second question. E.g. I have exercise (swimming) induced brachycardia (low heart rate), probably like most people here. So when I have to get an ECG for a swimming medical, I have context to explain. Without that context, well, maybe I have a problem.


  • There is a base line for glucose though. If you're not diabetic, your blood sugar level will be at a normal range between 80 and 100 (unless you just ate in the past two hours). If you're falling below that (say to 70) you have a concern. To 60and you have a fairly immediate problem that won't take a finger prick to diagnose. You'll break out in a cold sweat, you'll be disoriented, you'll be cramping up.

    If you do have type 2, and you're not scarfing donuts while you're swimming, you probably will have a higher BSL because you're sweating water out of the body and the whole BSL is a function of water/sugar ratio in the blood (which is why untreated/undiagnosed t2 diabetics drink so much water) as such (unless you're on insulin, which is a different kettle of fish from a Glucophage medication) a BSL is going to be skewed anyway.
  • ok. so what if its not for diabetic reasons or any other medical reasons.
    Say someone (college prof) just wants to take blood samples and monitor glucose and lactate acid levels during the actual solo swim for "research". However yet again refer to original post. No baseline done months ago before training, none taken during peak training sessions, or peak training months, and prob going to be no follow up after event.
    Also they are not providing "feed product" for swimmer, to see what works best and at what times. Also they have not stated @ what intervals they wish to monitor.
  • danswimsdanswims Portland, ORMember
    Say someone (college prof) just wants to take blood samples and monitor glucose and lactate acid levels during the actual solo swim for "research". However yet again refer to original post. No baseline done months ago before training, none taken during peak training sessions, or peak training months, and prob going to be no follow up after event.

    So if what one is interested in is the changes in glucose and lactate levels and/or heart rate throughout a prolonged swim I don't see that levels months before, during training or at some time well after the event would have any real relevance compared to a baseline level taken immediately before the event and then follow ups taken immediately afterward. The baseline and context depend greatly on what one is trying to look at. For a one off event it would not even be possible to make comparisons on feeds so that's pretty much a moot point. A single set of data on a single swim wouldn't really be research in the sense that actual conclusions could be drawn anyway. Gathering data during a single swim that is going to happen with or without the data collection could however be of some interest in generating ideas to develop a real study of some sort, sometimes one needs to figure out what questions might be worth asking.

    Lactate and glucose can both be measured from drops of blood and it appears to be possible to do this during a swim based on the comments of at least one diabetic swimmer on this forum who does it. It's impressive that this can be accomplished while surrounded by water, I must say.

    If it's not excessively intrusive on your swim and you can either 1) manage the blood samples yourself or 2) live with and be transparent about the fact that "touching" occurred why not do it, might or might not be interesting in the end. If it is excessively intrusive or otherwise unacceptable to you just say no.

  • danswimsdanswims Portland, ORMember
    Your heart rate monitor question may also be moot as I'm pretty sure I'm remembering from the manual of the one that I own, currently languishing in the bottom of the workout bag, that it can be worn while swimming but the chest strap and receiver can't manage to talk to each other while under water. There's also the distance limit thing from chest strap to receiver so if you decide to do this testing everything in advance would be important.
  • JenAJenA Charter Member
    edited June 2014
    I have type 1 diabetes, and I test my blood glucose levels every 30 minutes duribg swims. Currently, this is done by throwing me a waterproof container filled with equipment I need, which I can use while treading water. It is entirely unassisted, and takes a significant amount of time. However, with the continuous glucose monitoring technology on the market, glucose monitoring during swims is in the process of changing.

    Unless you have diabetes *and* are at risk for clinically relevant low blood sugar (this eliminates most people with type 2 diabetes) I would say that knowing your blood sugar level during the swim is assistive. When your blood sugar level is low, you can absorb more carbs than usual. Having this information could cause you to change your real-time nutritional strategy in response to blood sugar level, which would be an unfair advantage.

    I also feel that having a kayaker with HR information is also assistive. They will/could subconsciously alter their pacing to accommodate target heart rate zones.

    My motto: if it assists, it's assistive. For the most part, anyway. :-)
  • loneswimmerloneswimmer IrelandCharter Member
    edited June 2014
    It should be obvious by now that I know nothing about lactate and blood sugar testing or benefits.

    I do however have this (free) Android app (cardiograph) and it's great. Useful for monitoring improving fitness through morning resting heart rate, rhr. I also use it to check HR if I feel really tired or performed poorly during training, or am not getting enough sleep or even sometimes to realise I might have a low level infection. I've also used it just before ECGs and found it to be very accurate, reading within 2 bpm of the ECG.


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