ClimbSci is an evidence-based webcast covering scientific topics related to climbing and climbers, notably nutrition, training, recovery, and performance. Hosted by Brian Rigby (Climbing Nutrition), and Tom Herbert (usefulcoach).

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Episode 02 - Carbohydrate

In the second episode of ClimbSci, we discuss carbohydrates and how they fit into energy provision for climbers, including:

  • The anaerobic potential of carbohydrates
  • Carbohydrate’s oxygen-efficiency advantage
  • Glycogen and exogenous dietary carbohydrates
  • The reasons some people avoid carbohydrates
  • Practical aspects of carbohydrates and performance

We also answer three carbohydrate-related questions and wrap up the show with a research review!

If you have any questions or comments regarding the show, want us to investigate something specifically, or know any guests we should interview; please leave them in the YouTube comments, or head over to Brian’s page facebook/climbingnutrition and leave them on the wall.

Energy System Contribution

As mentioned throughout the episode, the energy systems overlap in their contribution to overall energy needs. Glucose (carbohydrates) are most importantly used without oxygen present “anaerobic glycolysis”, but also with oxygen present “aerobic glycolysis”.

Contents / Navigation

These timecodes are clickable when viewing on Youtube. For the sake of time, not all epsisodes are timecoded.

  • 0:03:45 What is the source of biological energy
  • 0:09:18 Why carbohydrates are unique
  • 0:12:28 Why we can’t sprint a marathon
  • 0:16:03 Overlapping energy systems
  • 0:24:20 Carbohydrates are oxygen rich
  • 0:29:34 Carbohydrates, power output, “fat adaption”
  • 0:37:35 EPOC (excess post-exercise oxygen consumption)
  • 0:38:28 Endogenous carbohydrate (glycogen), hydration, lactate
  • 0:46:39 Exogenous carbohydrate (dietary carbohydrate)
  • 0:48:01 Insulin, insulin resistance, health fears
  • 0:58:43 Carbohydrates and gaining fat (lipogenesis)
  • 1:05:17 Fear of sugar (sucrose), fructose
  • 1:09:00 Carbohydrates, inflammation, low-carbohydrate diets
  • 1:14:50 Dietary intake: applications and guidelines
  • 1:39:40 Considerations during menstrual cycle
  • 1:42:12 Listener question: sports drinks and reactive hypoglycemia
  • 1:47:23 Listener question: carbohydrate loading
  • 1:52:20 Listener question: carbohydrate supplement simple/complex mixes
  • 1:55:33 Quality of dietary carbohydrates (whole foods)
  • 1:57:37 Study review: Smith et al (2017). Nutritional Considerations for Bouldering
  • 2:00:00 Calories and performance: Athletes eat to support their training performance
  • 2:08:20 Closing remarks about the shows


All studies below were specifically cited in this episode. In general, if a study was not cited in the episode, we do not cite it here—even if we base a claim on it or similar studies. Expertise is a culmination of the time spent studying a topic, and it is not always practical to fully cite the research that has informed our professional opinion. If you have a question regarding the source of a specific claim we make, please contact us.

Specifically Referenced

  • 0:35:54 Burke, L. M., Ross, M. L., Garvican-Lewis, L. A., Welvaert, M., Heikura, I. A., Forbes, S. G., Hawley, J. A. (2017). Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers. The Journal of Physiology, 595(9), 2785–2807.
  • 0:35:54 Stellingwerff, T. (2005). Decreased PDH activation and glycogenolysis during exercise following fat adaptation with carbohydrate restoration. AJP: Endocrinology and Metabolism, 290(2), E380–E388.
  • 0:47:06 Haff, G. G., Stone, M. H., Warren, B. J., Keith, R., Johnson, R. L., Nieman, D. C., … Kirksey, K. B. (1999). The Effect of Carbohydrate Supplementation on Multiple Sessions and Bouts of Resistance Exercise. The Journal of Strength and Conditioning Research, 13(2), 111.
  • 1:02:26 Peterson, C. M., Zhang, B., Johannsen, D. L., & Ravussin, E. (2017). Eight weeks of overfeeding alters substrate partitioning without affecting metabolic flexibility in Men. International Journal of Obesity, (March), 1–32.
  • 1:02:26 Acheson, K. J., Schutz, Y., Bessard, T., Anantharaman, K., Flatt, J. P., & Jequier, E. (1988). Glycoprotein storage capacity and de novo lipogenesis during massive carbohydrate overfeeding in man. American Journal of Clinical Nutrition.
  • 1:22:40 Escobar, K. A., Morales, J., & Vandusseldorp, T. A. (2016). The Effect of a Moderately Low and High Carbohydrate Intake on Crossfit Performance. International Journal of Exercise Science, 9(3), 460–470. Retrieved from
  • 1:29:55 Marquet, L. A., Brisswalter, J., Louis, J., Tiollier, E., Burke, L. M., Hawley, J. A., & Hausswirth, C. (2016). Enhanced endurance performance by periodization of carbohydrate intake: “Sleep Low” strategy. Medicine and Science in Sports and Exercise (Vol. 48).
  • 1:39:40 Devries, M. C. (2006). Menstrual cycle phase and sex influence muscle glycogen utilization and glucose turnover during moderate-intensity endurance exercise. AJP: Regulatory, Integrative and Comparative Physiology, 291(4), R1120–R1128.
  • 1:39:40 Julian R, Hecksteden A, Fullagar HHK, Meyer T (2017) The effects of menstrual cycle phase on physical performance in female soccer players. PLOS ONE 12(3): e0173951.
  • 1:39:40 Sims, T. S. (2016). Roar: How to Match Your Food and Fitness to Your Female Physiology for Optimum Performance, Great Health, and a Strong, Lean Body for Life. ISBN 978-1-62336-686-5
  • 1:45:50 Chacko, E. (2017). A time for exercise: the exercise window. Journal of Applied Physiology, 122(1), 206–209.
  • 1:57:37 Smith, E. J., Storey, R., & Ranchordas, M. K. (2017). Nutritional Considerations for Bouldering. International Journal of Sport Nutrition and Exercise Metabolism, 10(1), 1–28.

Additional References

  • Bertuzzi RC de M, Franchini E, Kokubun E, Kiss MAPDM. (2007). Energy system contributions in indoor rock climbing. Eur J Appl Physiol. 101(3):293-300.
  • Gastin PB. (2001). Energy system interaction and relative contribution during maximal exercise. Sports Med. 31(10):725-741.
  • Horton TJ, Drougas H, Brachey A, Reed GW, Peters JC, Hill JO. (1995). Fat and carbohydrate overfeeding in humans: different effects on energy storage. Am J Clin Nutr. 62(1):19-29.
  • Spencer MR, Gastin PB. (2001). Energy system contribution during 200- to 1500-m running in highly trained athletes. Med Sci Sports Exerc. 33(1):157-162.

Further Reading

Carbohydrate Strategies For Climbing Performance

An In-Depth Look at Energy Metabolism: Part III

The Pros and Cons of Fructose

Why You Need More Oxygen to Burn Fat

Five Basic Lessons on Carbohydrates


Brian Rigby

Brian Rigby is a climber, sports nutritionist, and writer; he’s not so bad at handstands, either. He is the author behind Climbing Nutrition, a blog that aims to improve climbers’ understanding of how nutrition affects performance and help them climb better. Brian lives in Boulder, Colorado with his wife and two dogs, has a master of science in applied clinical nutrition, and is a certified (CISSN) sports nutritionist through the International Society for Sports Nutrition.

Climbing Nutrition / fb:climbingnutrition

Tom Herbert

Tom Herbert (aka “usefulcoach”) when not working full-time as a GNU/Linux System Administrator, works as a freelance strength and conditioning coach, and performance and change nutritionist certified (CISSN) through the International Society of Sports Nutrition. Based in London UK, Tom works with a number of Team GB climbers, enjoys bouldering, pole dancing (doing not watching), long walks, longer sentences, and is a serial user of the Oxford comma.

usefulcoach / fb:usefulcoach / @usefulcoach