Your gut has a
trainable ceiling.
Endurance performance at the amateur and semi-competitive level is capped by the gut, not the legs. Sweatr's Gut Training progressively raises your in-session fueling to the target you set — built around your real training.
Why gut training?
Most endurance performance is capped by the gut, not the legs.
Well-trained endurance athletes absorb 90–120 g of carbs per hour. Most recreational athletes fail well below that — hit with nausea, bloat, or urgency. Gut adaptation is real and trainable: absorption capacity increases with repeated high-carb exposure, especially during low-intensity sessions.
90–120 g/hr
Target range for well-trained endurance athletes
How it's different
Built the way gut
adaptation actually works.
Progressive targets
+10 g/hr per stage, stepping from your baseline to your target.
Symptom-adaptive
The program advances when your gut is ready — not on a calendar. Two consecutive clean sessions unlock the next stage.
Race-day confidence
A readiness score feeds directly into race-day plans: 'Trained to 90 g/hr with no symptoms for 3 consecutive sessions.'
How it works
From baseline
to race-ready.
- 01
Baseline tolerance test
One structured Z1–Z2 session at a conservative carb target. Log how your gut felt on a 1–5 scale.
- 02
Adaptive weekly progression
The engine sets each session's target based on your symptom history. Clean sessions unlock the next stage; rough ones hold the line.
- 03
Fuel source rotation
Glucose-only up to 60 g/hr. Above that, we switch to a glucose+fructose (2:1) mix to open the second absorption pathway.
- 04
Symptom → product insights
See which products your gut tolerates at which intensity. Surfaced in your Fuel Library after each session.
- 05
Readiness score
A composite score that feeds back into race-day confidence, built from clean-session streaks at each tolerance level.
Preview
See your program.
Set where you're starting and where you're headed. We'll build the stages.
Typical range for recreational endurance athletes.
Elite / pro range. Requires glucose + fructose (dual-transporter) fueling.
Above 60 g/hr needs dual-transporter fuel (glucose + fructose, 2:1). We'll flag it if your kit is missing one.
Your program
6 stages- Stage 140g/hrGlucose only
- Stage 250g/hrGlucose only
- Stage 360g/hrGlucose only
- Stage 470g/hrGlucose + fructose
- Stage 580g/hrGlucose + fructose
- Stage 690g/hrGlucose + fructose
Stages advance when you log two consecutive clean sessions at the current target — so the calendar flexes to your gut, not the other way round.
Key terms
The science, in plain terms.
- Gut training
- A structured protocol that progressively raises an endurance athlete's in-session carb-absorption ceiling through repeated high-carb exposure during low-intensity sessions.
- Carb-absorption ceiling
- The maximum carbohydrate intake (in grams per hour) an athlete can tolerate during exercise without GI symptoms. Well-trained endurance athletes typically reach 90–120 g/hr.
- Dual-transporter fueling
- Using a glucose + fructose mix (typically 2:1 ratio) to recruit two separate gut transporters — SGLT1 for glucose and GLUT5 for fructose — enabling carb intake above 60 g/hr.
- SGLT1 / GLUT5
- The two intestinal sugar transporters. SGLT1 absorbs glucose and saturates around 60 g/hr; GLUT5 absorbs fructose. Training upregulates both.
- Clean session
- A training session where the athlete hits the target carb intake and logs a gut-comfort score of 4 or 5 out of 5 with no specific GI symptoms. Two consecutive clean sessions unlock the next stage.
- Readiness score
- A composite metric describing an athlete's race-day fueling confidence, built from clean-session streaks at each tolerance level.
Common questions
Gut training, explained.
The science behind the program, and what to expect when you run it.
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