103. Transition from short to long distance Triathlon: Nutrition insights from pro triathlete Grace Thek

In this episode of Fuelled, I’m joined by professional Australian triathlete Grace Thek, who recently made her full-distance debut at Challenge Roth — finishing second in her very first attempt. Grace has long been a middle-distance triathlete, but stepping up to the full Ironman distance brought new challenges, particularly around training load, recovery, and race-day nutrition.

We chat about her journey from collegiate running, through years of managing injuries, to racing on the world stage. Grace shares candidly about the doubts she had about even making the start line, the changes she made in her preparation, and the crucial role that fuelling played in helping her handle 25-hour training weeks without breaking down.

Grace also walks us through her detailed fuelling strategy for Roth — how she went from taking in 60–70g carbs per hour to averaging 94g on the bike and 90g on the run, without GI distress. We explore practical lessons from her trial and error, including using flasks for gels, managing sodium, and testing caffeine.

If you’re a triathlete curious about stepping up to the full distance, or simply want insight into how the world’s best manage their fuelling, this episode is packed with practical takeaways. Grace also shares advice for beginner triathletes — including her own hard-earned lesson from bonking at her first 70.3 race.

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TRANSCRIPT

Fuelling for Full Distance: How Grace Thek Powered Her Ironman Debut

When professional Australian triathlete Grace Thek lined up at Challenge Roth for her first full-distance triathlon, simply making the start line felt like a victory. Years of stress fractures and soft-tissue injuries had made her question whether her body could handle the jump from middle distance to Ironman. But not only did she make it — she finished second in one of the world’s most iconic long-course races.

The Step Up to Ironman

Grace turned pro in 2018, specialising in middle-distance racing. The full Ironman distance had always been in the back of her mind, but the heavy training load required — combined with her history of injuries — kept her cautious. That changed this year. With a new coach and a commitment to finally take on the challenge, she built her biggest training blocks ever, regularly clocking 24–26 hours a week.

The difference this time? Smarter fuelling.

Learning to Fuel Training

Previously, Grace rarely fuelled during training. Most sessions were under two hours, so she got away with just eating before and after. But preparing for a full-distance race meant five-to-seven-hour rides with runs off the bike — effectively missing lunch. To stay healthy and recover, she had to embrace intra-session fuelling.

Carb mixes, gels, and trialling race nutrition in training became the norm. She learned that even in the last 30 minutes of a long ride, a gel wasn’t wasted — it was setting up recovery for the next session.

Race-Day Nutrition at Challenge Roth

Grace’s fuelling strategy on race day was meticulous.

• Bike: 340g carbs via carb mix, plus gels and electrolyte tablets, totalling 94g carbs/hour and ~520mg sodium/hour.
  
  

• Run: 12 gels (90g carbs/hour), carried in flasks diluted with water for easier sipping.
  
  

• Pre-race: Toast with honey, banana, and one coffee 2.5hrs before start, plus two gels before the swim.
  
  

The result? No bonk, no GI issues, and feeling strong enough to finish her marathon with her best kilometres in the final stretch.

Lessons from Trial and Error

Grace admits she used to think, “I don’t need it” when it came to fuelling. That belief cost her dearly in her first 70.3 in Geelong, where she bonked, collapsed on the finish carpet, and literally crawled over the line. It’s a mistake she’s determined never to repeat.

Now, her advice is clear: test your fuelling in training, aim higher with carbohydrate intake than you think you need, and always have a backup plan in case bottles or gels get dropped.

Moving Forward

Grace has fallen in love with the full distance and plans to race more Ironmans in 2025, while still competing at middle-distance and T100 events. For her, nutrition is no longer an afterthought — it’s a performance tool that keeps her healthy, resilient, and able to race at her best.

For beginner triathletes, Grace’s advice is simple: have fun, make training social where you can, and never underestimate the importance of fuelling.

Her own story is proof: when you get the nutrition right, you give yourself the chance not just to finish — but to thrive.