Managing Energy for Rides Over 10 Hours: Fatigue Curves and Pacing Adjustment Strategies

Introduction

Riding for more than 10 hours is a watershed moment. Before this point, most riders with a training base can get through on stored glycogen and a solid aerobic system; after this point, the body enters a state where multiple systems are simultaneously under stress—micro-damage to muscle fibers accumulates, core body temperature regulation pressure rises, the nervous system begins to fatigue, and the digestive system’s absorption efficiency declines.

Taiwan has many classic challenges exceeding 10 hours: round-island rides (from the 10-day version to the 3-day version), Wuling double ascents, 500km north-south traversals, and more. To complete these challenges, you must learn to make smart decisions under fatigue.

The Physiological Mechanisms of Fatigue

Fatigue in ultra-long rides is not caused by a single factor, but is a compound effect of multiple systems breaking down simultaneously:

The 3 Phases of the Fatigue Curve

Phase 1 (0–4 hours): Peak Efficiency Period
The body uses stored glycogen as its primary fuel, operating at peak efficiency. During this phase, ride at your planned pace—don’t let good feelings tempt you into riding too fast. Pro riders call this phase “waiting by the tree for the rabbit”—the energy you save here becomes a true asset in Phase 3.

Phase 2 (4–8 hours): Metabolic Transition Period
Glycogen stores begin to decline, and the body attempts to shift toward fat oxidation for energy. The problem is that fat oxidation is 30–40% less efficient than carbohydrate metabolism. During this transition, if fueling is insufficient, a “bonk” (energy crash) can easily occur.

• Warning signs: sudden leg weakness, slowed thinking, low mood (“why did I sign up for this ride”)
• Response: immediately consume fast-acting carbohydrates (juice, energy gels); recovery typically occurs within 20–30 minutes of fueling

Phase 3 (8+ hours): Willpower-Dominated Period
By this stage, physical capacity is significantly fatigued, and ride quality is largely determined by mental state and smart decision-making. Successful ultra-distance riders no longer rely on “brute force” at this stage—they start using their heads.

Specific practices:

• Proactively assess body condition every 20–30 minutes (don’t wait until problems arise to address them)
• Deliberately ease off before climbs to protect heart rate
• Accept that pace decline is a normal physiological response; don’t force yourself to maintain earlier speeds

A Practical Framework for Pacing

The “10% Rule”:
If your average speed in any 30-minute segment falls more than 10% below plan, this is a clear sign of overload. You must immediately replenish energy and drop intensity by one zone.

Heart Rate as the Primary Pacing Metric:
Power output declines with fatigue, but heart rate is a more reliable indicator. For rides exceeding 10 hours, it’s recommended to use “keeping heart rate below the upper limit of Zone 2” as your pacing guideline, rather than chasing a fixed speed.

Pacing considerations for long-distance riding in Taiwan:

• Downhill sections on Taiwan’s mountain roads can easily lead to “over-resting,” causing muscles to cool down and making the next climb harder
• If riding during the hottest hours (11am–3pm), heart rate will run higher due to heat stress—don’t force yourself to maintain speed

Practical Recommendations

1. Establish a personal fatigue rating system: Rate your subjective fatigue (RPE) on a 1–10 scale every hour. If it exceeds 8 for two consecutive hours, you must proactively reduce intensity or seek replenishment
2. Practice riding in a fatigued state: Deliberately design “tired-leg long rides” in training—complete a high-intensity workout, then follow it the next day with a 3–4 hour Zone 2 ride to simulate the conditions of a real ultra-long ride
3. Set a “minimum pace floor” for each segment: Establish a minimum acceptable speed for every 50km segment. If you fall below this threshold for more than 30 minutes, take a full rest (get off the bike, stretch, refuel)
4. Rotate pacing with partners (if available): On rides exceeding 10 hours, taking turns at the front with teammates can save 15–20% of energy expenditure

Conclusion

Riding for more than 10 hours teaches you far more than any training plan. You’ll learn what your body truly looks like at the edge of its limits—what breaks down first, what foods help you recover fastest, and what mindset keeps you going longer.

Between Taiwan’s magnificent mountains and coastline, ultra-distance riding is a special adventure. And mastering energy management is the key to ensuring that adventure has not only a heroic beginning, but also a beautiful ending.

Related Reading

• Managing Cumulative Fatigue in Multi-Day Rides: Strategies for Round-Island or Stage Races
• Climbing Strategies for Multi-Day Races: Fatigue Management for Three Consecutive Days of Climbing
• Recovery and Nutrition Management for Multi-Day Races: Complete Training and Logistics for the Taiwan Challenge
• Road Cycling Fatigue Syndrome: Identifying and Recovering from Chronic Fatigue Caused by Long-Term Training