By: Roxanne Vogel, MS, CSCS*D, ACSM-EP, CISSN

What limits human endurance? Is it our body that limits us, or is it all in our minds? A bit of both, maybe? And, how might we (safely) overcome some of these limitations?

As a mountaineer and ultra-endurance runner, these questions have long fascinated me. They are what motivated me to pursue my PhD research on human endurance, performance, and how we push ourselves to the extremes— and in extremes—such as heat, cold, hypoxia.

I’m also the Nutrition and Performance Manager at GU Energy Labs, the company that introduced energy gels to the world of sports nutrition. My job at GU involves running our Performance Lab, working in R&D to develop new products, educating all types of athletes on nutrition and performance-related topics, and conducting research. Currently, I’m developing a sports nutrition product to help athletes feel and perform better in the heat. That’s where you come in: I’m looking for well-trained runners to take part in my study at Texas Woman’s University in Denton. This project will determine if a ‘cooling’ energy gel improves performance during exercise in a hot environment.

We are seeking female endurance runners who are currently training 3 or more sessions per week and can run continuously for least 60 minutes. Participants will have had experience running on a motorized treadmill, and will have regularly performed moderate-vigorous intensity running during training.

The study will assess the effect of a ‘cooling’ energy gel as a method of improving heat tolerance, mood, and performance during exercise in the heat. You will be asked to test two different energy gels on separate occasions during ~60 min treadmill running in a heated environment. You will also be required to complete a maximal aerobic capacity (VO2max) test prior to testing the gels. We will collect information on heart rate, body temperature, and mood/cognition assessments during your runs.

General requirements:

  • 18-40 years of age
  • Trained female endurance runner
  • Does not use tobacco of any kind
  • Healthy and injury-free
  • No known or suspected intolerances to any of the energy gel ingredients

All participants will receive a free VO2max assessment by a certified exercise (a $150 value!) and a $50 gift card for completing all lab visits. Participation is voluntary and may be discontinued at any time.

To register for more information and to find out if you qualify for the study, follow this link.


Roxanne Vogel, PhD(c), CSCS*D, ACSM-EP CISSN, is the Nutrition and Performance Research Manager at GU Energy Labs where she oversees the brand’s Performance Lab and works with elite athletes to optimize nutrition for performance, health, and longevity. She is a PhD candidate in Exercise Physiology at Southern Cross University, Australia, where her research focuses on nutrition interventions to support human performance in environmental extremes, including heat, cold, and hypoxia. A mountaineer and ultra-endurance athlete, in 2019 she became the first person in history to summit Mt. Everest door to door in two weeks, and in 2020 completed the “Seven Summits” by successfully climbing the highest peak on each continent. She has spent the past decade researching nutrition and its impact on body composition, athletic performance, and cognitive function.