Wearable sweat sensors have entered the market promising easy, accurate, repeatable, and in some cases, real-time feedback on sweat fluid and sodium losses. But do the claims live up to the hype? In this episode, we’ll unpack who these devices might be relevant to, the options currently available on the market, how they work, and most importantly, are they accurate?

Timestamps:

01:01 - Fueling Endurance updates - eBook, Practitioner Membership, Podcast

05:31 - What are wearable sweat sensors?

12:08 - The first step - smart sweat patches

13:39 - Reusable, wearable sweat sensors

20:31 - Nix Biosensor device

22:38 - hDrop

23:09 - Flowbio - newly published validation study

28:47 - My own experiences and comparisons

35:06 - Where does this leave us now?

36:20 - Additional considerations

41:39 - The problem interpreting individual validation studies

43:29 - Wrap up

Research mentioned in this episode:

Baker LB. et al. (2020). Skin-interfaced microfluidic system with personalized sweating rate and sweat chloride analytics for sports science applications. Sci Adv. 6:eabe3929. doi: 10.1126/sciadv.abe3929

Bandiera D. et al. (2026). Sweat sodium composition and sweat loss estimation through wearable sensors and predictive equations in dry and humid hot conditions. Front Physiol. 16:1717275. doi: 10.3389/fphys.2025.1717275

Fueling Endurance eBook | T -12 Race Nutrition Course | Practitioner Resources

The Fueling Endurance eBook contains answers to 49 of the most common nutrition questions that runners, cyclists and triathletes ask, and contains insights, tips, and quotes from experts and athletes.  The T -12 self-guided course will help prepare you for your next event, with online tools, guides, information and instructions to take you through the 12 weeks leading up to race day. And the Fueling Endurance Practitioner Membership provides access to online tools and calculators I use all the time when working with endurance and ultraendurance athletes. This includes working out the carbohydrate needs for runners (road and trail) and cyclists for different types of training sessions. For more into on each of these, check out fuelingendurance.com.

It's the end of 2025, and like each previous year we’re looking back and providing a brief summary of every question we’ve answered on the podcast in the past year, from “Are high carb diets a health concern for athletes?” to “Do I need a multivitamin?”, and “Can I trust AI with my sports nutrition questions?”. So if you’re new to the podcast and don’t have time to go through the whole back catalogue, or you just want a refresher and the key points from the past year's episodes, this is the place for you.

Timestamps:

01:15 - Are high carb diets a health concern for athletes?

03:43 - How does sports nutrition evolve?

05:47 - What is periodised nutrition, and is it beneficial?

10:12 - Can GLP-1 agonists work for runners, cyclists and triathletes?

12:55 - Does nutrition have a role to play in injury prevention?

15:00 - Should I go gluten-free?

17:53 - Can I predict my sweat losses without actually measuring them?

20:13 - Can I trust AI with my sports nutrition questions?

25:03 - Can menthol improve my performance in the heat?

26:57 - Do I need a multivitamin?

30:22 - Is there an optimal drink mix composition?

34:32 - How should I use the new TrainingPeaks carbohydrate and fat calorie metrics?

37:22 - Are omega-3's important for athletic performance?

40:53 - Can my nutrition reduce the chances of getting sick?

44:44 - How much sodium do I need before, during, and after exercise?

48:49 - Can I change my gut microbiome, and will it help me as an athlete?

51:46 - How do I manage exercise, nutrition, and Type 1 Diabetes?

54:05 - 5th anniversary special - Data-driven nutrition planning for ultra-distance events

54:52 - What is exogenous carbohydrate oxidation testing, and how would it benefit me?

59:37 - Wrap up

Fueling Endurance eBook | T -12 Race Nutrition Course | Practitioner Resources

The Fueling Endurance eBook contains answers to 49 of the most common nutrition questions that runners, cyclists and triathletes ask, and contains insights, tips, and quotes from experts and athletes.  The T -12 self-guided course will help prepare you for your next event, with online tools, guides, information and instructions to take you through the 12 weeks leading up to race day. And the Fueling Endurance Practitioner Membership provides access to online tools and calculators I use all the time when working with endurance and ultraendurance athletes. This includes working out the carbohydrate needs for runners (road and trail) and cyclists for different types of training sessions. For more into on each of these, check out fuelingendurance.com.

In the past decade, we've gone from low carb to high carb. Are we now heading towards a new era of personalised carb? In this episode I speak to two experts about exactly what exogenous carbohydrate oxidation is, how the testing works, who might benefit from this type of testing, and how to interpret the results.

Timestamps:

04:09 - Tim and Gareth's background and research

10:50 - What is exogenous carbohydrate oxidation?

11:41 - How do you test exogenous carbohydrate oxidation rate?

16:26 - How should an athlete prepare for exogenous oxidation testing?

19:10 - The importance of doing the test properly

22:50 - Are we testing maximal oxidation capacity, or replicating race conditions?

23:44 - What's the real-world benefit of exogenous carbohydrate oxidation testing?

28:17 - Making this testing available to athletes

33:58 - Assumptions, caveats and limitations to exogenous oxidation testing

37:33 - The difference between relative and absolute exercise intensity - does it matter here?

40:52 - What happens when you overfeed carbohydrate during exercise

43:59 - Why Tim and Gareth only test for glucose (and not fructose) oxidation

47:13 - How carb intake recommendations are made based on test results

50:58 - Can you improve exogenous oxidation through exercise or gut training?

57:26 - The (very) high carb trend - will testing help prevent unnecessary carb intake?

1:00:48 - Who might benefit most from testing, and do gut issues predict oxidation abiilty?

1:07:35 - Unanswered questions in this area

1:10:37 - Bonus Round

1:13:42 - Summary, unanswered questions and wrap up

Research mentioned in this episode:

Podlogar T, Cooper-Smith N, Gonzalez JT, Wallis GA. (2025). Personalised carbohydrate feeding during exercise based on exogenous glucose oxidation: a proof-of-concept study. Performance Nutrition. 1:2. doi: 10.1186/s44410-025-00003-9

Dr Tim Podlogar:

University of Exeter: experts.exeter.ac.uk/43996-tim-podlogar

Instagram: @tpodlogar

LinkedIn: linkedin.com/in/timpodlogar

Prof Gareth Wallis:

University of Birmingham: birmingham.ac.uk/staff/profiles/sportex/wallis-gareth

LinkedIn: linkedin.com/in/gareth-wallis-8291a441/

Oxidation testing service (Fuel Sync) coming in Jan 2026

Fueling Endurance eBook | T -12 Race Nutrition Course | Practitioner Resources

The Fueling Endurance eBook contains answers to 49 of the most common nutrition questions that runners, cyclists and triathletes ask, and contains insights, tips, and quotes from experts and athletes.  The T -12 self-guided course will help prepare you for your next event, with online tools, guides, information and instructions to take you through the 12 weeks leading up to race day. And the Fueling Endurance Practitioner Membership provides access to online tools and calculators I use all the time when working with endurance and ultraendurance athletes. This includes working out the carbohydrate needs for runners (road and trail) and cyclists for different types of training sessions. For more into on each of these, check out fuelingendurance.com.

It’s the fifth anniversary of the podcast! In this special episode, we’re joined by Paul Booth, who put together the nutrition plan for both the men’s and women’s winners of the 2025 Ultra Trail du Mont Blanc, or UTMB. We’ll hear how lots of different topics from previous podcasts came together for these two world class athletes, how lab testing helped inform their nutrition strategies, and how it pays to personalise your strategy based on the athlete’s own data, and not just follow the trends that all the top guys and girls are doing. 

Timestamps:

05:42 - Paul's background and PhD research

11:04 - Paul's role as lead nutritionist for Salomon

18:03 - The evolution in the professionalism of nutrition in ultra trail running

23:46 - Working with the men's and women's winners of UTMB

28:32 - The use lab testing to inform carb intake strategies

38:30 - Understanding the demand for carbs across the event and how the course terrain shapes this

43:30 - Beyond just a grams per hour target - planning carbs and food/fluids for ultra-distance events

54:44 - Gut training for Ruth and Tom

58:09 - Hydration and sodium replacement testing and planning

1:06:32 - Crewing at UTMB

1:09:41 - Reflections on nutrition planning for UTMB and other ultra-distance events

1:11:20 - Applying the lessons from elite athletes to the everyone else

1:16:36 - Bonus Round

1:18:43 - Summary and wrap up

Paul Booth:

Instagram: @ultra.endurance.nutritionist

Website: performancegainsnutrition.com 

If you're interested in participating in Paul's research (in the UK): performancegainsnutrition.com/contact

Fueling Endurance eBook | T -12 Race Nutrition Course | Practitioner Resources

The Fueling Endurance eBook contains answers to 49 of the most common nutrition questions that runners, cyclists and triathletes ask, and contains insights, tips, and quotes from experts and athletes.  The T -12 self-guided course will help prepare you for your next event, with online tools, guides, information and instructions to take you through the 12 weeks leading up to race day. And the Fueling Endurance Practitioner Membership provides access to online tools and calculators I use all the time when working with endurance and ultraendurance athletes. This includes working out the carbohydrate needs for runners (road and trail) and cyclists for different types of training sessions. For more into on each of these, check out fuelingendurance.com.

Juggling training, nutrition, and day-to-day life can be a challenge. But throw in the complexities of Type 1 Diabetes, and it’s a whole new ball game. In this special episode to coincide with World Diabetes Day, I'm joined by co-founder of Enhance-d and former head of research at Team Novo Nordisk, Sam Scott. Sam gives us a peek into the world of diabetes management for the endurance athlete. We’ll discuss what Type 1 diabetes actually is, how it’s managed, the impact of exercise, and the innovations in devices and data management that are making life a little easier to make this all work. Whether you’re an athlete with Type 1, a nutrition practitioner, or you’re just curious what it’s all about, there’ll be plenty in this episode for you.

Timestamps:

03:13 - Sam's background and how he came to work in diabetes and exercise

13:07 - What is Type 1 Diabetes and how is it managed?

25:57 - How does exercise affect blood glucose control with Type 1 Diabetes?

35:26 - Giving insulin with a pen vs a pump for athletes

41:38 - 'Closed loop' systems for glucose monitoring and insulin delivery in athletes

45:41 - Does high volume endurance training make diabetes management harder?

50:11 - Sam's role at Team Novo Nordisk (professional cycling team where all riders have Type 1 Diabetes)

56:59 - Tech and data insights, including Sam's role in founding Enhance-d, and the role of AI in diabetes management

1:08:28 - Very low carb diets and the very high carb (during exercise) trend in athletes with Type 1 Diabetes

1:11:33 - The future of nutrition, exercise and Type 1 Diabetes

1:14:13 - Summary and wrap up

Sam's work:

LinkedIn: linkedin.com/in/sam-scott-phd-620a97a2/ 

Sam's book: Empowered: The Science of Exercise with Type 1 Diabetes (available from Amazon)

Enhance-d (bringing together data on exercise and diabetes management): enhance-d.com 

Fueling Endurance eBook | T -12 Race Nutrition Course | Practitioner Resources

The Fueling Endurance eBook contains answers to 49 of the most common nutrition questions that runners, cyclists and triathletes ask, and contains insights, tips, and quotes from experts and athletes.  The T -12 self-guided course will help prepare you for your next event, with online tools, guides, information and instructions to take you through the 12 weeks leading up to race day. And the Fueling Endurance Practitioner Membership provides access to online tools and calculators I use all the time when working with endurance and ultraendurance athletes. This includes working out the carbohydrate needs for runners (road and trail) and cyclists for different types of training sessions. For more into on each of these, check out fuelingendurance.com.

The gut microbiome is a term that's thrown around a lot. But what does it actually mean? Is there a particular gut microbiome that's more common in athletes? And should athletes be trying to shape their microbiome to benefit their health or performance?

Timestamps:

02:10 - What is the gut microbiome?

13:50 - What are short chain fatty acids, and what's their significance?

18:00 - How do you determine someone's microbiome?

23:59 - Species vs strain of microbiota

30:08 - Is there an "athletic microbiome" that's common to most athletes?

32:00 - Effect of pre/pro/syn/postbiotics on performance

42:38 - Effect of pre/pro/syn/postbiotics on illness prevention and treatment

45:44 - Effect of pre/pro/syn/postbiotics on gut issues during exercise

52:12 - Practical advice for using pre/pro/syn/postbiotics

55:30 - Bonus round and Monash University study

59:14 - Summary and wrap up

Read the research paper (open access):

Gaskell S et al. Gut microbiota and exercise: A systematic review of interventions and evidence limitations. Int J Sports Med. 2025: doi: https://doi.org/10.1055/a-2705-2210 

Current study recruiting at Monash University (looking for distance runners aged 18-55): https://www.monash.edu/medicine/scs/nutrition/research/volunteer#Pre-Exercise 

Fueling Endurance eBook | T -12 Race Nutrition Course | Practitioner Resources

The Fueling Endurance eBook contains answers to 49 of the most common nutrition questions that runners, cyclists and triathletes ask, and contains insights, tips, and quotes from experts and athletes.  The T -12 self-guided course will help prepare you for your next event, with online tools, guides, information and instructions to take you through the 12 weeks leading up to race day. And the Fueling Endurance Practitioner Membership provides access to online tools and calculators I use all the time when working with endurance and ultraendurance athletes. This includes working out the carbohydrate needs for runners (road and trail) and cyclists for different types of training sessions. For more into on each of these, check out fuelingendurance.com.

There’s been a lack of clear guidelines around how much sodium to take before, during and after exercise, to optimise health and performance. That created a vacuum, which anyone with a vested interest was more than happy to fill with suggestions. But we’re now getting to the stage where we can make some more specific, quantifiable recommendations about sodium for endurance athletes, before, during and after exercise. I had the privilege of being invited to put these recommendations together, so in this episode, I’ll walk you through them.  

Timestamps:

02:37 - Do athletes need more sodium on a day-to-day basis?

14:42 - Sodium before exercise

25:25 - Sodium during exercise

44:32 - Sodium after exercise

49:28 - TLDL: Summary

52:13 - Unanswered questions

Read the research paper (open access):

McCubbin AJ. Sodium intake for athletes before, during and after exercise: review and recommendations. Performance Nutrition. 2025; 1:11. doi: https://doi.org/10.1186/s44410-025-00011-9

Fueling Endurance eBook | T -12 Race Nutrition Course | Practitioner Resources

The Fueling Endurance eBook contains answers to 49 of the most common nutrition questions that runners, cyclists and triathletes ask, and contains insights, tips, and quotes from experts and athletes.  The T -12 self-guided course will help prepare you for your next event, with online tools, guides, information and instructions to take you through the 12 weeks leading up to race day. And the Fueling Endurance Practitioner Membership provides access to online tools and calculators I use all the time when working with endurance and ultraendurance athletes. This includes working out the carbohydrate needs for runners (road and trail) and cyclists for different types of training sessions. For more into on each of these, check out fuelingendurance.com.

There seems to be two types of endurance athletes - those who are always getting sick when their training volume increases, and those who don’t. But why? In this episode we investigate the evidence around nutrition, the immune system, and illness in athletes, and come to a conclusion of what you can do to prevent getting sick during those hard training blocks, and bounce back quickly when illness does strike.

Fueling Endurance eBook | T -12 Race Nutrition Course | Practitioner Resources

The Fueling Endurance eBook contains answers to 49 of the most common nutrition questions that runners, cyclists and triathletes ask, and contains insights, tips, and quotes from experts and athletes. 

The T -12 self-guided course will help prepare you for your next event, with online tools, guides, information and instructions to take you through the 12 weeks leading up to race day.

And the Fueling Endurance Practitioner Membership provides access to online tools and calculators I use all the time when working with endurance and ultraendurance athletes. This includes working out the carbohydrate needs for runners (road and trail) and cyclists for different types of training sessions.

For more into on each of these, check out fuelingendurance.com.

Fish oil, or omega-3 supplements, are one of the most widely used supplement among the general population. But there's also been suggestions of specific benefits for athletes. 

So what exactly are omega 3’s? What do they do in the body? What foods and supplements do they come from, and most importantly, do the benefits live up to the marketing hype when it comes to health and performance?

Studies/Websites mentioned:

AIS Sports Supplements Framework - Fish Oil (Group B): https://www.ausport.gov.au/ais/nutrition/supplements/group_b/other/fish-oils 

Fueling Endurance eBook | T -12 Race Nutrition Course | Practitioner Resources

The Fueling Endurance eBook contains answers to 49 of the most common nutrition questions that runners, cyclists and triathletes ask, and contains insights, tips, and quotes from experts and athletes. 

The T -12 self-guided course will help prepare you for your next event, with online tools, guides, information and instructions to take you through the 12 weeks leading up to race day.

And the Fueling Endurance Practitioner Membership provides access to online tools and calculators I use all the time when working with endurance and ultraendurance athletes. This includes working out the carbohydrate needs for runners (road and trail) and cyclists for different types of training sessions.

For more into on each of these, check out fuelingendurance.com.

Fuelin:

This episode is supported by Fuelin, the world's first training-based nutrition app. It syncs with your training plan (in TrainingPeaks, Final Surge, TriDot, Run Dot or Humango) and creates a personalised nutrition plan, built around your training schedule and tailored to your goals. You’ll see adjustments in your fuelling both within and outside of training sessions, using a traffic light system to adjust your carb intake to fuel appropriately for your needs. The new-look Version 2 app has just launched, providing an even better user experience.

To get 20% off your first month, go to fuelin.com and enter the code FE20 at checkout.

TrainingPeaks just launched a new set of data fields that promise to give insights into carbohydrate and fat use during exercise - even predicted amounts for planned sessions if enough data is provided.

So where did this come from? What is it telling us? How should I use this information? And is it unique, or are there other ways to achieve the same thing?

Studies/Websites mentioned:

TrainingPeaks Fueling Insights: https://www.trainingpeaks.com/coach-blog/introducing-fueling-insights/ 

Rothschild J et al. A Novel Method to Predict Carbohydrate and Energy Expenditure During Endurance Exercise Using Measures of Training Load. Sports Med. 2025; 55:753-774. https://doi.org/10.1007/s40279-024-02131-z 

Fueling Endurance eBook | T -12 Race Nutrition Course | Practitioner Resources

The Fueling Endurance eBook contains answers to 49 of the most common nutrition questions that runners, cyclists and triathletes ask, and contains insights, tips, and quotes from experts and athletes. 

The T -12 self-guided course will help prepare you for your next event, with online tools, guides, information and instructions to take you through the 12 weeks leading up to race day.

And the Fueling Endurance Practitioner Membership provides access to online tools and calculators I use all the time when working with endurance and ultraendurance athletes. This includes working out the carbohydrate needs for runners (road and trail) and cyclists for different types of training sessions.

For more into on each of these, check out fuelingendurance.com.

Fuelin:

This episode is supported by Fuelin, the world's first training-based nutrition app. It syncs with your training plan (in TrainingPeaks, Final Surge, TriDot, Run Dot or Humango) and creates a personalised nutrition plan, built around your training schedule and tailored to your goals. You’ll see adjustments in your fuelling both within and outside of training sessions, using a traffic light system to adjust your carb intake to fuel appropriately for your needs. The new-look Version 2 app has just launched, providing an even better user experience.

To get 20% off your first month, go to fuelin.com and enter the code FE20 at checkout.