Running Race Planner

How the Running Race Planner Works

Run your best race with a science-based plan. This tool combines proven performance models, sports nutrition science, and environmental physiology to create a personalized race blueprint.

Whether you're racing your first 5K or targeting a marathon PR, proper planning can mean the difference between achieving your goal and hitting the wall. This planner integrates multiple scientific pillars into one comprehensive race-day strategy.

The Science Behind the Planner

1. VDOT Performance Model

Developed by legendary coach Jack Daniels, VDOT represents your effective VO₂max derived from race performance. Unlike laboratory testing, VDOT captures not just physiological capacity but also running economy and race-day execution.

VDOT = (−4.60 + 0.182258×S + 0.000104×S²) / (0.8 + 0.1894×e^(−0.0128×T) + 0.2990×e^(−0.193×T))
Where S = speed (m/min) and T = time (minutes)

From a single race result, we can predict performances at other distances and calculate optimal training paces. The model accounts for the relationship between oxygen cost and the sustainable fraction of VO₂max across different durations.

2. Pacing Strategy

Research consistently shows that pacing strategy significantly impacts performance. Our approach is distance-specific:

Distance	Strategy	Rationale
5K / 10K	Near-even pacing	Controlled start with optional fast finish
Half Marathon	Slight negative split	First half at 98-99% goal pace, build into second half
Marathon	Conservative negative split	First 10km at 97% goal pace to preserve glycogen

Studies of successful marathon finishers (Santos-Lozano et al., 2014) show that even or slight negative splits are associated with faster times compared to positive splits (slowing down).

3. Energy & Glycogen Model

Running burns approximately 1.0 kcal per kilogram of body weight per kilometer. Your muscles store 400-600 grams of glycogen (more with proper carb loading), providing 1,600-2,400 kcal of energy from carbohydrates alone.

The planner estimates your glycogen depletion curve based on pace and intensity, then calculates how much exogenous carbohydrate you need to avoid "hitting the wall." It also respects gut tolerance limits based on your training level.

4. Hydration & Sodium Model

Fluid needs vary significantly between individuals and conditions. Based on ACSM guidelines, we target 50-80% sweat replacement to avoid both dehydration (>2-3% body mass loss) and overhydration (weight gain).

Parameter	Typical Range	Notes
Sweat Rate	0.5-2.0 L/hour	Varies with intensity, heat, humidity
Fluid Target	400-800 ml/hour	Based on sweat rate and conditions
Sodium	300-600 mg/hour	Higher for salty sweaters in hot conditions

5. Environmental Adjustments

Heat, humidity, and altitude all impair performance. The planner integrates research-based adjustments:

How to Use Your Race Plan

Scientific References

• Daniels, J. (2014). Daniels' Running Formula (3rd ed.). Human Kinetics.
• Jeukendrup, A. (2011). Nutrition for endurance sports. British Journal of Sports Medicine.
• Burke, L. M., et al. (2011). Carbohydrates for training and competition. Journal of Sports Sciences.
• Santos-Lozano, A., et al. (2014). Pacing strategies in marathon runners. PLOS ONE.
• Mantzios, K., et al. (2022). Temperature effects on running performance. Sports Medicine.
• Wehrlin, J. P. & Hallén, J. (2006). Altitude and sea-level training. Medicine & Science in Sports & Exercise.
• ACSM Position Stand (2007). Exercise and fluid replacement.

Important Disclaimers

This planner provides science-informed estimates based on population averages and established research. Individual responses can vary significantly based on genetics, training history, race-day conditions, and many other factors.

Always prioritize your health and safety. If conditions feel dangerous or you experience concerning symptoms, adjust your effort or stop. This tool is for planning purposes and does not constitute medical or professional coaching advice.