• Dr. Sims – Science Guru to the Pro’s

    by  • March 29, 2011 • interviews, tech, womyn on weels • 11 Comments

    NorCal is not just a hotbed for riders.  It is a center of research and development for the entrepreneurs and scientists that develop the technology that speeds up the pro peloton and is consumed by every day cyclists. Dr. Stacy Sim’s is an accomplished athlete in her own right having ridden for TIBCO, won multiple Xterra events, and her secret past as a pro tri-athlete.  Her cutting edge research with athletes has led her to work with the likes of Garmin, RadioShack and Lance Armstrong where she helps riders of all abilities find the extra edge through science .  Dr. Sims, or Stacy to her NorCal friends, is the go to person for to top coaches when they are looking for the extra, legal, edge.

    You are one of the scientists that has contributed to some of the top cycling programs in the world (Garmin, RadioShack) what aspects of your research have been used by the pro’s?

    The short answer – hydration plans and formulas, heat stress and adaptation plans, race specific and recovery nutrition, and of course thermoregulation plans have been adopted by individuals in the pro-peloton (not just Garmin and Radioshack) as well as professional Ironman athletes, USACycling women’s track program, and most recently USA Women’s Field Hockey.

    Give me the long answer, I want some details for all the NorCal engineering nerds that I know read this (I’m talking about you Connelly!)

    I am usually pigeon-holed into one aspect of what I know and do. At a high level I am known for my work on nutrition or thermoreg. But it is the combination of everything that allows me to go in, assess the riders situation & environment, then set up a series of in-the-field tests to get enough data to illustrate what intervention needs to be done; and the hard data to support the outcome. For example- if someone is looking to perform well in a one day classic- the limiting factor(s) will usually include hydration, thermoregulation, nutrition-the days leading up to the race as well as race day, and, depending on the rider’s physique-the specific baselayer they wear. All of these tie hand-in-hand-> the rider needs to go into a long race with a higher than normal body water content- this can come from heat and/or altitude exposure to expand total blood volume (plasma volume is the essential fluid compartment for sweating; red cell mass is essential for aerobic exercise- but you need expanded PV to keep circulation high and to allow sweat rates to meet the exercise and environmental demands), or if no time has been allocated for heat or altitude stress, going into the race “preloaded” with a high sodium beverage- with sodium comes water, and you can get a buffering effect by altering the sodium compound ingested- sodium bicarb or sodium citrate or both… Then during the race, paying attention to keeping the hydration separate from fueling needs- you can come back from low blood sugar but you can’t come back from dehydration.

    [Dr. Sim’s hobnobbing with big shots]

    And so I should go out and buy some super sharp Campagnolo artfully ripped base layer shirts?

    The last of the trifecta is the clothing, esp the baselayer- I’ve done quite a bit of research on the performance properties of merino wool (see SmartWool’s website for most of the outcomes)- and merino wool tends to help thermoregulate much better than the standard technical fabrics- wool is a natural fiber and responds well to the microclimate between fabric and skin; technical fibers haven’t quite gotten there yet..

    Did you meet any resistance when working with the athletes on these teams or were they receptive to doing things differently?

    A few were dubious at first, but more to the fact that I’m a girl- most women aren’t on the inner circles but are more support staff or wives; not the scientist. It takes a few times of me ignoring the flirting banter for some to realize I am there as a scientist to help them get faster/get an edge. Makes me laugh actually!  Almost all are very receptive though- pulling out the pee sticks usually cuts to the chase!

    Say “pee stick” again… it makes me giggle.

    I’m serious about the pee stick! I pull em out at every camp- people freak out then get intrigued like it’s a crystal ball- “you’re dehydrated and you went really hard in your last training session… ” then the next day it’s the first thing they ask for!

    Will scientists be the next rockstars on the ProTour?

    My hope is that sport scientists will have more of a presence on the ProTour, or even across sports- instead of compartmentalizing aspects of performance and outsourcing to bike companies (for fit), clothing companies, or even old school ideas (just ride on water OR ride on liquid calories…) I’d like to see more teams coming aboard the science bandwagon-to actually get the research based information for performance, rather than the marketing claims which people take for science.

    You’re an entrepreneur as well, You’ve started up a venture for your hydration mix which people can learn more about your IM project at http://www.secretdrinkmix.com/.  So this is taking cutting edge technology and brining it to the people.  Will it help improve local athletes performance like 45 year old Cat 5 masters racers?

    So. this lends to my above comment about marketing claims which people take as science. Sports drinks are neither a good fuel nor a good hydrator-> regardless of category, you need to think of hydration in the bottle and food in the pocket. Again, you can come back from low blood sugar by eating some jelly beans or swedish fish or other quick hit sugar, but once hypohydration comes into play, you can just watch your power and race decline- it takes time to “refill” the body water compartments, and as little as a 2% body weight loss can equate to an 11% decline in VO2max- so no sprint for you if you’re dehydrated!

    The IM drink is one of the outcomes from my work at Garmin at the TdFrance. We formulated it to have more sodium (>300mg per serving) and just enough carbohydrate to maximize fluid absorption- the sugars used (sucrose and glucose) work to maximize fluid in and minimize GI distress. The focus is on fluid absorption, whereas the calorie needs have to come from another source (there are only 80 calories per 16oz). We also didn’t like the glow-in-the-dark colours of traditional sports drinks, so we went with freeze-dried fruit powder for flavour.

    All of this plays into the slowing down dehydration and maximizing your performance.

    You have a funny accent!  I think you spent too long in New Zealand

    Don’t be a dumbass, I know where you live.

    Your passion for endurance sports seems to take your research in directions that is of extreme interest to cyclists and their equipment suppliers.  Are there any topics that you are looking at now that you are looking at?

    I’m just finishing up a project looking at cooling during time trial efforts to increase critical power. Very interesting results. Basically, keeping the core temp at ~38’C tends to allow for greater power output. I believe it has more to do with the temperature of the muscle and the physiology of muscle contraction/innervation rather than specific core temperature itself.

    The next project I’m kind of excited about is a follow on to early work I did in New Zealand with the NZ Merino Association- I’m going to be looking at different fabrics and weaves of fabrics as baselayers. I know that merino is an interesting fiber in that it responds to the microclimate of the skin to fabric-e.g. keeps you cool when it’s hot and keeps you warm when it’s cold; but we don’t know if a silk top weave with merino will be better, or a goretex combination etc.. So, as a science geek, to use fabric to enhance the thermoreg capabilities of the body will be very interesting!





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    Former NorCal resident now residing in Madison,Wisconsin. I race cross, but I'm named after a velodrome. Support your local bike shop, NorCal race promoters, and go learn to race on a track. Hellyer Velodrome - http://www.ridethetrack.com


    11 Responses to Dr. Sims – Science Guru to the Pro’s

    1. amanda
      March 29, 2011 at

      Super stoked to see that Stacy’s going to mass produce her drink mix! I got to try some out last year and it was delicious. ETA on when we can buy some??

    2. Stacy
      March 29, 2011 at

      Hiya Amanda! Thanks!
      You can go to secretdrinkmix.com and email Aaron from the info link on the webpage (contact@secretdrinkmix.com) and buy it now. raspberry or orange…

    3. Bernie
      March 29, 2011 at

      I would like to get the independent research-based information for performance of your sports drink. Can you give us a link comparing your drink to the other top drinks?

      Cooling from the outside of the body raises the core temperature, cooling from the inside lowers it. I noticed (maybe it is just an old picture) that Lance was being cooled with an ice vest, which was shown in independent studies over 12 years ago to be inferior to the cooling glove by the Australians.(More info @ http://www.avacore.com)

      If the doctors have recent information disputing this, it would be great to see the research.

      In the second to the last paragraph, it says keeping core temp cool allows for greater power output. Then it says it is muscle innervation/temp rather than core. Please explain.


    4. Margene Sims
      March 30, 2011 at

      A very interesting article to review all the hard work Stacy has been doing over the years. She has a passion to help cyclists and other athletes.
      I don’t agree with the accent though. I am a very proud mom.
      Margene Sims

    5. Bill Shugarts
      March 30, 2011 at

      Great work Stacy!! Hang-in-there, have fun with it all & best wishes for success with Im!!

    6. Bernie
      March 30, 2011 at

      I was wondering why the moderator decided not to publish my post, or have the doctor answer my questions about her methods and products. I suspect the reason may have something to do with an invalid arguement and faulty research on the doctor’s side, but I may be wrong about this. Can you email me and let me know why?

    7. March 30, 2011 at

      Well, since I was referenced here, I feel obligated to make a comment/question… 🙂

      The high sodium levels in the drink are an interesting contrast with Hammer Nutrition’s philiosophy of “less salt in = less salt out”, where electrolyte replacement is from a broader selection of minerals (for which Hammer recommends capsules, perhaps not so convenient in mass-start racing as in century riding). On the other hand, the recommendation to decouple nutrition from fluids seems to be in close agreement ( http://www.hammernutrition.com/forums/viewtopic.php?f=4&t=86 ).

    8. March 30, 2011 at

      Bernie – my initial feeling was that your comment was automatically thrown into the pending comments queue because the filter recognized a slightly crazy and emotionally exhausting vibe. However… after looking into it, it was just the link in your post. We have a big spam problem and it looks like comments with links get automatically moderated by our high tech wordpress askimet comment technology. I put it through… i know Stacy is off to New Zealand this week, so you might try contacting her through the drink mix company if you want data.

    9. Bernie
      March 30, 2011 at

      I appreciate you looking into it, thank you.

    10. March 30, 2011 at

      If you do a pubmed search on stacy sims you can get links to her academic research which i assume the science for the drinks is based on…


    11. Matt
      March 31, 2011 at

      There is also the reference section from the hyperlinked article on “cutting edge hydration strategies” –


      1.Maughan, R. J., and T. D. Noakes; Fluid replacement and exercise stress: a brief review of studies on fluid replacement and some guidelines for the athlete. Sports Med. 12:16-31, 1991.
      2.Takamara, A., Y. Tetsuya, N. Nishida, and T. Morimoto; Relationship of osmotic inhibition in thermoregulatory responses and sweat sodium concentration in humans. Am J Physiol Regulatory Integrative Comp Physiol 280: R623-R629, 2001.
      3.Gillen, C. M., T. Nishiyasu, G. Langhans, C. Weseman, G. W. Mack, and E. R. Nadel; Cardiovascular and renal function during exercise-induced blood volume expansion in men. J Appl Physiol, 76: 2602-2610, 1994.
      4.Hargreaves, M., and M. Febbraio; Limits to exercise performance in the heat. J Sports Med., 19: S115-S116, 1998.
      5.Montain S. J., and E. F. Coyle; Influence of graded dehydration on hyperthermia and cardiovascular drift during exercise. J Appl Physiol, 73(4):1340-1350, 1992.
      6.Sanders, B., T. D. Noakes, and S. C. Dennis; Sodium replacement and fluid shifts during prolonged exercise in humans. Eur. J. Appl. Physiol., 84:419-425, 2001.
      7.Sims ST, Rehrer NJ, Bell ML, Cotter JD. Preexercise sodium loading aids fluid balance and endurance for women exercising in the heat. J Appl Physiol 103: 534-541, 2007.
      8.Sims, ST, L vanVliet, JD Cotter, and NJ Rehrer. “Sodium loading aids fluid balance and reduces physiological strain of trained men exercising in the heat.” Medicine and Sciences in Sports and Exercise, 39 (1), 123-130, 2007

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