Cognitive Function in Cycling: Study on Declining Decision-Making Ability After Prolonged Riding

Introduction

During Stage 17 of the 2019 La Vuelta, after five consecutive hours of mountain riding, several riders showed delayed judgment on descents, leading to dangerous overtaking and collisions. Post-race analysis by team medical advisors pointed to a frequently overlooked issue: Mental Fatigue—it is not the muscles, but the brain, that is the final link to collapse during long-distance riding.

Mental fatigue refers to the subjective feeling of tiredness and the objective decline in cognitive performance resulting from prolonged tasks requiring attention, including the execution of complex motor skills. For cyclists, mental fatigue affects not only strategic decision-making but is also directly related to safety during high-speed descents.

Mechanisms of Mental Fatigue Induced by Long-Duration Riding

Brain Energy Consumption

The human brain weighs approximately 1.4 kg, only 2% of body weight, yet it consumes 20% of the body’s resting metabolic energy. During prolonged riding:

• Brain glucose consumption is closely related to blood sugar levels
• Hypoglycemia directly affects the executive function of the Prefrontal Cortex
• Studies show that after 90 minutes of riding without carbohydrate intake, reaction time on decision-making tasks increases by approximately 8–15%

Adenosine Accumulation Mechanism

A deeper mechanism involves the neurotransmitter adenosine:

• Prolonged brain activity causes adenosine to gradually accumulate in the brain
• When adenosine binds to its receptors, it transmits a “fatigue signal” to the brain
• This is precisely the principle by which caffeine (an adenosine antagonist) can enhance cognitive performance
• Studies show that after prolonged cognitive tasks, the accumulation effect of adenosine can be quantitatively observed in subsequent physical performance

Competitive Neural Resource Hypothesis

The “resource competition hypothesis” proposed by Blazer et al. argues that:

Prolonged high-difficulty riding (such as technical descent sections or commuting in heavy traffic) requires sustained attentional resources. The depletion of these cognitive resources is itself a form of “non-muscular fatigue” that compounds with metabolic muscle fatigue, accelerating the overall decline in performance.

Key Findings from Quantitative Research

Changes in Cognitive Test Metrics

Data based on pooled estimates from multiple studies; individual differences are significant

Impact of Mental Fatigue on Riding Safety

Simulation experiments on road cycling conducted by Pagel et al. (2021 research direction) showed:

• After 4 hours of riding, reaction time in simulated hazardous traffic situations increased by approximately 15%
• The frequency of Lane Deviation increased by approximately 25%
• Subjective Rating of Perceived Exertion (RPE) was overestimated under mental fatigue conditions, affecting pacing decisions

Strategies for Protecting Cognitive Function

Neurological Benefits of Carbohydrate Supplementation

Studies consistently show that maintaining stable blood glucose levels is the most effective strategy for protecting cognitive function:

• Supplementing 30–60g of carbohydrates per hour can reduce the cognitive decline associated with prolonged riding by approximately 30–40%
• Solid food (energy bars) vs. liquid (energy gels + water): both forms show similar effectiveness, but liquids are absorbed faster during high-intensity efforts
• Caffeinated energy gels are more effective than pure carbohydrates for maintaining cognition during rides exceeding 3 hours

Cognitive Protective Effects of Caffeine

Practical Recommendations

1. Establish a fueling alarm habit: Set reminders every 20–30 minutes to avoid forgetting carbohydrate intake due to mental fatigue
2. Use caffeinated energy gels for rides over 3 hours: Using caffeinated products in the latter half is a scientifically supported strategy for maintaining cognition
3. Perform a cognitive self-assessment before descents: During long rides, proactively evaluate your attentional state before entering descents; if you feel “spaced out” or sluggish, slow down or stop to rest
4. Develop awareness of non-fatigue indicators: Learn to distinguish between “muscle fatigue” (legs feeling weak) and “mental fatigue” (difficulty concentrating, hesitation in decision-making)—the two require different coping strategies
5. Quality sleep is the best prevention: Studies show that less than 7 hours of sleep the night before accelerates the rate of mental fatigue during prolonged riding by approximately 40%

Conclusion

Mental fatigue in cycling is a long-underestimated factor in both performance and safety. Scientific research clearly demonstrates that the decline in decision-making ability after prolonged riding is not merely a subjective feeling but an objective phenomenon supported by neurophysiological mechanisms. Recognizing this phenomenon and adopting targeted fueling and rest strategies is a crucial element in enhancing the safety and racing intelligence of long-distance cycling.

Related Reading

• Neuroscience and Cycling Tactical Decision-Making: The Impact of Cognitive Load on Race Strategy
• The Impact of Mental Fatigue on Physical Performance: Declining Exercise Capacity After Mental Work
• Cycling and Cognitive Function: The Scientific Impact of Aerobic Exercise on the Brain
• Cycling Cardiorespiratory Endurance and Cognitive Performance: The Benefits of Riding for Brain Health