• Triathlete Julie Dunkle excelled at IRONMAN 70.3 Oceanside to claim 1st place in her age group (F55-59). Julie was stoked with the result and said post-race, “from start to finish, it was just amazing”
• Julie has always suspected that her fluid and sodium losses were high and she confirmed those suspicions in 2019 when she started to get a handle on her individual losses by undergoing some extensive laboratory sweat testing to determine both her sweat rate and sweat sodium concentration in different conditions
• As Julie’s net fluid and sodium losses can become significant, she has been developing a flexible hydration plan ahead of the IM World Champs in St George, Utah. Julie discussed her strategy with the Precision Fuel & Hydration Sports Science team before the race in order to gain some confidence in what she was planning to do

Hydration

• Julie’s Sweat Test confirmed that she’s a ‘salty sweater’, losing ~1,200mg of sodium per litre of sweat, so she made sure she went into this race optimally hydrated by preloading with ~500ml/16oz of PH 1500 the night before, as well as on the morning of the race
• Julie had planned to drink two ~500ml/16oz bottles on the bike with PF 30 Drink Mix. However, this plan went out of the window when she got to her bike in T1 and found that one bottle was missing and the other was empty due to a leak! Consequently, Julie rode the first 18 miles of the bike leg with no fluid
• As soon as she could, Julie strived at every opportunity to pick up the on-course hydration which provided her with an intake of ~679mg of sodium and ~540ml/17oz of fluid per hour. This meant that at the end of the bike leg, the relative sodium concentration (a measure of the sodium content vs. fluid volume) of her intake was ~1,257mg/L
• During the run, Julie thought she had to play catch-up with her sodium losses because of the issues with her bike bottles, so she consumed a 500ml/16oz bottle containing two PH 1000 tablets and one serving of PF 30 Drink Mix, as well as three salt tablets. Therefore, the relative sodium concentration of her intake on the run was much higher (~3,738mg/L)
• Given the relatively cool conditions at Oceanside, Julie could have reduced her sodium intake and / or dialled up her plain water consumption to account for the fact that her net sweat losses were unlikely to be too great. The fact she tolerated such high numbers bodes well for her hydration strategy ahead of the IM World Champs in St George, Utah, where conditions are likely to be much hotter and Julie’s net sweat sodium losses will therefore be considerably higher
• Julie mentioned that she peed once during the bike leg indicating that she was well hydrated at that point. She didn’t pee again until finishing and she described her urine as “dark in color”, possibly indicating slight underhydration as a result of not drinking enough on the run. Julie could consider picking up additional plain water on the run, but in this race she felt her strategy was sufficient because her “sweat rate felt relatively low during this race”
• After a bit of a wobbly start in terms of hydration on the bike, Julie’s ability to adjust to the circumstances quickly meant her performance wasn’t too affected by the loss of her two pre-prepared bottles

Fueling

Conclusions

• From start to finish Julie thought her fueling and hydration strategy at IM 70.3 Oceanside “went great”. Despite losing her bottles on the bike and having to go without fluid for a time, Julie did really well to adapt and pick up what she could
• In retrospect, given the cooler conditions and her own observation that she wasn’t sweating too heavily, Julie could have dialled down her sodium intake on the run
• Julie consumed a solid amount of carbohydrate during the race, which could be pushed slightly higher in future races to meet the Quick Carb Calculator’s recommendations of 60-90g/hr for events of this duration and intensity