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TrainingPeaks Fueling Insights vs. Hexis: What athletes should know

Fueling to support training load and recovery is one of the best things we can do to improve training adaptation and performance capability. Tools like TrainingPeaks Fueling Insights and Hexis are designed to support that process, but in very different ways. Here's what we need to know about how they work, their assumptions, and when to use each one.


TrainingPeaks Fueling Insights

Fueling Insights gives athletes a view into substrate utilization, specifically the estimated amount of fat and carbohydrate used as fuel sources during exercise.


How it works

TrainingPeaks Fueling Insights uses power data and athlete metrics (weight, FTP, self-categorized athlete level or metabolic profile) to estimate carbohydrate and fat oxidation. These estimates are based on estimated respiratory exchange ratio (RER) from individual lab studies and stoichiometric equations that use RER, VO2 and VCO2 to predict rate of carb and fat oxidation at given intensities.


What it shows

Pre- and post-workout breakdown of estimated carbohydrate vs. fat use in total calories, plus calorie expenditure as calculated by adding the estimated fat calories to estimated fat calories. (Note: in the TrainingPeaks app and TrainingPeaks without Fueling Insights enabled, calorie expenditure is based on kJ and gross metabolic efficiency, assuming cyclists are between 21-22% efficient during exercise.)


Assumptions

  • Substrate use is not fixed, but instead influenced by exercise duration, intensity, sex, and dietary intake before and during exercise.

  • Assumes the athlete is well stocked with glycogen stores at baseline

  • Assumes the athlete is in a fed state without knowing actual intake timing or content of pre-exercise meal

  • Assumes athletes should replace ~50% of carbohydrate oxidized, a simplification that may not apply to all sessions

  • Total session energy expenditure appears to be calculated in a way that may overestimate calories compared to using work output in kilojoules, accounting for gross metabolic efficiency.

  • Self-selecting and changing a metabolic profile may significantly effect the calculations.


Why it matters

  • Reinforces the need for carbohydrate fueling even in longer, lower-intensity endurance sessions

  • Provides a platform to teach why athletes should eat more before and during higher-intensity or key sessions

  • Helps explain why carbs matter and provides context for fueling conversations, but its assumptions mean it should be used as a guide, not a prescription



Hexis

Hexis takes a forward-looking, prescriptive approach, offering individualized daily guidance, including carbohydrate intake and fueling that matches training demands.


How it works

Hexis integrates with TrainingPeaks to analyze planned sessions' average watts, time of day, and importance (training, key performance session, or competition). It updates the day dynamically after syncing with TrainingPeaks post-workout.


What it shows

  • Provides day-by-day and meal-level carbohydrate recommendations, as well as during session carbohydrate fueling targets

  • Also provides day and meal-level energy and macro (protein, carb, and fat) recommendations that adjust dynamically based on profile settings, workouts, and actual intake reported.

  • Adjusts the remainder of the day after the completed workout is synced, using actual post-workout power data and self-reported fueling and nutrition intake inputs to Hexis

  • Provides short- and long-term trends for how the athlete is doing with fueling (energy and macros) relative to training


Why it matters

  • Offers a comprehensive solution aligned with fuel for the work required

  • Helps athletes avoid the common under-fueling problem in both key and long endurance rides

  • Adjusts dynamically with the training plan; prescriptions are specific to context rather than generic rules

  • Gives actionable steps for total energy intake and macronutrient intake and timing, rather than simply estimated substrate oxidation for the session


Bottom line: Hexis is a planning and execution tool. It gives athletes the what and when of fueling to directly support performance, as well as health and body composition. Click here to subscribe to Hexis for BaseCamp.


Example

Fig 1: Post-event using Fueling Insights
Fig 1: Post-event using Fueling Insights
Fig 2: Post-event data without Fueling Insights
Fig 2: Post-event data without Fueling Insights
Fig 3: Pre-event plan in Hexis
Fig 3: Pre-event plan in Hexis
Fig 4: Post-event after sync with TP in Hexis
Fig 4: Post-event after sync with TP in Hexis

Let us know in the comments if you are using either TrainingPeaks Fueling Insights or Hexis and how it has helped you this season!


At BaseCamp, we believe that every cyclist has the potential to achieve greatness, no matter where they start. Our mission is to create a community-driven training environment where cyclists and triathletes of all levels can train together, support each other, and grow stronger, faster, and more confident in their abilities. Our cycling training programs are expert driven and tailored to your needs. Whether you're a seasoned pro or just getting started, BaseCamp is where you belong.

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