Blood Sugar and Performance

The graph presents a simple, highly simplified visual model of how perceived performance can change with decreasing blood glucose levels.

The main message is that glucose concentration cannot merely be categorized as "normal" or "low," but can also be associated with a gradually deteriorating cognitive and physical state.

Scientific Approach

Physiologically, glucose is a primary energy source for the brain, so a drop in blood sugar can indeed cause attention deficits, impaired reaction times, irritability, tremors, or weakness.

However, the graph displays this relationship in an overly direct, linear manner, because in reality, symptoms are highly dependent on individual adaptation, the speed of the blood glucose drop, insulin levels, prior nutritional status, and whether the individual is chronically accustomed to lower or higher glucose values.

The "performance" scale in the image is more illustrative than a clinically validated measurement tool.

Values around 100 mg/dL can be perfectly adequate for many healthy individuals.

Performance degradation becomes much more pronounced when glucose drops to the lower end of the physiological range, especially if this happens quickly.

Blood sugar is not an indifferent variable, and its decrease can have a noticeable effect on well-being and cognitive function.

 

Performance and Blood Glucose Values

• 140 mg/dL: Performance is at its maximum, 100%.
• 125 mg/dL: According to the graph, performance begins to decrease but is still at a high level.
• 100 mg/dL: Performance drops to approximately 85%. The caption states: "You might feel 100%, but you're not optimized."
• 75 mg/dL: Performance begins to plummet suddenly, reaching 75%. "You're about to bonk, but you don't even know it yet."
• 60 mg/dL: Performance drops to 50%. "You might feel good, but your focus is already impaired."
• 40 mg/dL: Performance drops to a critically low level, only 5%. Severe hypoglycemic range.

 

What is a "bonk"?

A term used in endurance sports for the sudden, severe onset of exhaustion.

It is caused by the complete depletion of glycogen stores and a drop in blood sugar levels.

 

Summary

Overall, the graph highlights that decreasing blood glucose levels can lead to a decline in mental and physical performance, but the relationship is not so simple and not the same for everyone.

The image is illustrative but should be treated with caution, as the real physiological response is more complex than this.

 

 

Sport and Blood Glucose: CGM-based Exercise Optimization