Sodium Supplementation for Ultrarunning with Alan McCubbin PhD | Koopcast Episode 159
Episode overview:
Dr. Alan McCubbin lectures and conducts research in sports nutrition at Monash University, consults to Triathlon Australia's High Performance Program, and writes for Cycling Tips. He has worked as the dietitian for the Attaque-Gusto cycling team, adventure runner Richard Bowles, several triathlon squads, the Coburg Tigers VFL football club and the Tour de Cure cycling charity amongst others. He has written for Outer Edge Magazine, Trail Run magazine and lectured for Cycling Australia coaches. He has worked with summer and winter Olympians, A-League soccer players, national Taekwondo champions, triathletes, ultra-marathon runners, road cyclists & mountain bikers, boxers and windsurfers. Alan has competed at an international level in sailing, and in endurance mountain biking. Alan recently completed a PhD in sports nutrition at Monash University, looking at the effects of sodium in endurance athletes. He is also the co-host of The Long Munch Podcast, a podcast that answers common nutrition questions asked by runners, cyclists and triathletes.
Alan founded Next Level Nutrition, Australia's first ever online sports nutrition consultancy back in 2010. What was once an unheard of service model is fast becoming the norm in the sports nutrition industry, better servicing the sporting community of Australia with access to state-of-the-art sports nutrition counseling and education, delivered to clients anywhere in Australia via the web.
Episode highlights:
Part one — interview:
(15:14) When to supplement sodium: large sweat losses, high fluid intake, high sweat sodium concentration, example
(45:55) Decision chart for sodium replacement: check out Alan’s flow chart in the show notes, when to use sodium supplementation in training, season to taste
Part two — coach roundtable:
(1:35:28) Lower access to fluids during training: differences in resupplying, loop training, using your vehicle as an aid station
(2:06:00) Duncan’s takeaways: more 4+ hours runs, emphasizing that sodium is per unit fluid, train in varied environmental conditions
Our conversation:
Part one — interview:
(0:00) Intro: the complexity of sodium balance, introducing Alan and the research, breaking the “nothing new on race day” advisory
(2:23) Introducing the coach round table: new format, post-interview discussion of research applications
(3:59) The complexity of hydration: confounding factors, differing advisories, the value of research
(6:49) Study setup: research question, using established equations to quantify sodium balance, banter, specificity to ultramarathons
(10:05) Context to sodium balance: the role of sodium in cramping
(12:42) Sodium should balance fluids: hypernatremia and hyponatremia, risks, safe fluid intake, salting to taste
(15:14) When to supplement sodium: large sweat losses, high fluid intake, high sweat sodium concentration, example
(17:38) Take sodium with fluid: the roles of sodium, physiology, sodium stimulating thirst
(20:16) Example: calculating fluid and sodium replacement in an Iron Man, over-replacing sodium
(21:46) Fluid is harder to replace than sodium: athletes will tend to over-replace sodium relative to fluids
(23:00) Sodium in sweat: the body reabsorbs 45-85% of sodium from sweat, but none of the water
(25:03) New sodium measurement patches: do not replace all sodium lost
(26:40) Body mass loss: examples, fluid loss, accumulated sweat loss, training versus racing
(29:54) Avoiding critical blood-sodium concentrations: suggesting a normal clinical range, no individual target value, the role of sodium is to balance fluids, not to optimize performance
(33:18) Total body water: the impact of hydration level on performance, lower hydration increases perceived effort, cardiac drift, and body temperature, total body water versus plasma volume
(36:01) Setting up Alan’s sodium intake presentation: is it necessary, is it practical, is it achievable
(38:00) Necessary sodium intake: only required when you are replacing over 70% of your fluid losses
(39:19) Practical sodium intake: Kipchoge example, practical sodium intake at high intensity and gut tolerance, sweat rate example, soft flask example
(41:40) Achievable sodium intake: soccer example, working around limitations to fluid accessibility
(42:36) When to supplement sodium: season to taste for less than four hours, decisions based on sweat rate for more than four hours
(45:55) Decision chart for sodium replacement: check out Alan’s flow chart in the show notes, when to use sodium supplementation in training, season to taste
(48:00) Sodium supplementation is not often necessary: challenges with overprecision in marketing, sodium and fluid replacement, placebo effect, supplementing differently between training and race day
(52:22) Deriving the 70% fluid loss benchmark: setting up the Gatorade study, fluid intake has more impact on sodium concentration than sodium intake, study methods
(55:36) Misinterpretations of the Gatorade study: Tim Noakes, examining the effect of water versus sodium, a potentially “cherry picked “ data set
(58:02) When sodium replacement becomes relevant relative to fluid intake: the 70% benchmark is a 50-90% benchmark, depending on whether you are a salty or non-salty sweater
(1:00:18) Determining if you are a salty sweater: collecting sweat, whole-body washdown procedure, impractical for runners
(1:03:01) Sweat patch testing: comparing patches and wearables, sweat concentration varies based on part of the body, sweat sodium varies with diet and day-to-day
(1:05:02) Problems with eyeballing sweat saltiness: environmental considerations, duration, variability
(1:07:35) Practical sweat testing: hope for wearables, impracticality of the wash-down test
(1:09:06) Interview wrap-up: giving thanks, practicality of the research, setup for coach discussion, Alan’s caveats on precision, where to find Alan
Part two — coach roundtable:
(1:12:54) Intro to coach roundtable: Ryne on addressing athlete questions and interpreting data sources
(1:14:55) Nicole on following general advisories: is it safe to over supplement sodium to cover losses, complications with interpreting physiological models, different strategies for different situations
(1:18:32) Duncan on the differences between training and racing: increasing athlete exposure to 4+ hour training runs to increase sodium replenishment specificity to race day, Koop’s example of practical fluid loss
(1:21:02) Three important variables: starting sodium concentration, sweat sodium concentration, and fluid loss, all difficult to acquire, using body weight to determine sweat loss, using fluid replenishment to guide when to start sodium replenishment
(1:24:47) Sweat test practicality: multiple environmental conditions, old body weight testing during races, fluid intake can vary by 3-4x depending on temperature and environment, learning tool for athletes, Leadville example
(1:28:05) Making hydration training practical: running during the heat of the day, training different from race day, slowing down to take in fluid
(1:30:46) Frederic on practicing fluid intake: getting used to high fluid intake
(1:32:45) Keep calories and fluids separate: limitations of carbohydrate uptake, intensity similarity between training and race day
(1:35:28) Lower access to fluids during training: differences in resupplying, loop training, using your vehicle as an aid station
(1:37:19) Estimating sweat-sodium losses: ballpark numbers work for most athletes, calorie analogy
(1:41:06) Heat training: your sweat rate changes from sauna protocols and running in heat, sweat rate on race day is what matters
(1:44:40) Drinking to thirst: viability in shorter training runs, lack of applicability to ultramarathons, using Alan’s decision tree
(1:47:19) Sweat testing: accuracy, Precision Hydration, functionality of a questionnaire in place of physiological testing, the high-medium-low sweat-sodium concentration metric
(1:51:22) Over-supplementation: runners often think they need to replace more sodium and fluids than is necessary or efficient, running culture, examples
(1:54:53) Sodium supplementation units: product recommendations, sodium replacement relates to fluid replacement and not to time, ease of use
(1:58:13) Mixed units: calories and fluid are per time, but sodium is per fluid, CTS training camp nutrition and hydration protocol
(2:01:58) Frederic’s model and Koop’s takeaways: Fred’s sodium calculator, numerical targets, there is no known optimal sodium concentration
(2:06:00) Duncan’s takeaways: more 4+ hours runs, emphasizing that sodium is per unit fluid, train in varied environmental conditions
(2:07:38) Nicole’s takeaways: mastering hydration in training is key, sodium and calories are more adaptable, most non-ultramarathon athletes need not worry about sodium replacement
(2:10:42) Ryne’s takeaways: keep it simple, practice hydration, be prepared to take additional fluids on race day because the demands will be higher, challenges of extrapolating training to race day
(2:12:54) Frederic’s takeaways: practice, measure, create a flexible strategy, Koop’s 90% rule, avoiding the mental stress of overthinking during races
(2:15:38) Wrap-up: giving thanks
(2:16:05) Outro: where to find Alan, giving thanks, additional resources, request for user feedback
Additional resources:
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