Every feature in Interactive Race Strategies is built on sports science research and real-world coaching experience. Here's what's under the hood.
Your pace plan automatically accounts for every hill on the course. No more blowing up on climbs or leaving time on the table on descents.
When you generate splits, the algorithm analyzes the elevation change for each mile and adjusts your target pace accordingly. Uphill miles get more time; downhill miles get less, so your effort stays consistent even when the terrain doesn't.
Research shows that for every 100 feet of elevation gain per mile, runners slow by approximately 10 seconds/mile. On downhill sections, pace improves by roughly the same amount, but with diminishing returns on steep descents due to braking forces and quad fatigue.
Our algorithm applies ~5 seconds per 50 feet of gain, with symmetrical recovery on downhills. This keeps your perceived effort steady rather than your GPS pace, which is what actually determines whether you'll bonk at mile 20.
Based on: Minetti et al. (2002) "Energy cost of walking and running at extreme uphill and downhill slopes"; Vernillo et al. (2017) "Biomechanics and physiology of uphill and downhill running"
Starting 7 days before your race, we pull the actual forecast for your course location and calculate exactly how much to adjust your pace.
Heat, humidity, wind, and rain all impact marathon performance. Most runners ignore weather until race morning, and by then it's too late to adjust your goal. Our tool shows you the impact days in advance so you can set a realistic target.
The optimal marathon temperature is 45–55°F (7–13°C). Performance degrades predictably above this range:
Based on: Ely et al. (2007) "Impact of weather on marathon-running performance"; El Helou et al. (2012) "Impact of environmental parameters on marathon running performance"
Humidity above 60% in warm conditions (>60°F) impairs evaporative cooling, adding 5–12 seconds/mile. Wind impacts at roughly 1 second/mile per 3 mph of headwind, assuming partial headwind exposure on a typical marathon course.
Rain below 50°F adds 2–5 seconds/mile due to wet clothing weight and reduced traction. Heavy rain adds 3–8 seconds/mile regardless of temperature.
Based on: Vihma (2010) "Effects of weather on the performance of marathon runners"
Select your exact fuel products, and we'll build a mile-by-mile fueling schedule that hits your carb targets, backed by sports science.
The calculator factors in your body weight, expected finish time, and specific fuel products (GU, Maurten, Clif, candy, bananas, and 20+ other options) to generate a customizable intake schedule. Add a pre-race breakfast plan too.
Current evidence-based guidelines for endurance athletes (ACSM, ISSN, Jeukendrup 2014):
At higher intake rates (>60g/hr), using multiple transportable carbohydrates (e.g., maltodextrin + fructose, as in Maurten) allows greater absorption because glucose and fructose use different intestinal transporters (SGLT1 and GLUT5). This is why products like Maurten Gel 160 can deliver 40g per serving without GI distress.
Pre-race breakfast: 1–4g carbs per kg body weight, consumed 2–3 hours before the start. This tops off liver glycogen stores depleted overnight.
Based on: Jeukendrup (2014) "A step towards personalized sports nutrition"; Thomas et al. (2016) ACSM Position Stand; Kerksick et al. (2017) ISSN Position Stand
Coaches can assign a perceived effort level per mile, and the system automatically recommends a corresponding pace to keep athletes in the right zone.
The effort scale maps directly to pace: 5/10 = your average goal pace (the exact pace needed to hit your target finish time). Each point up or down adjusts pace by ~2% of your average, a meaningful but manageable shift.
The Rating of Perceived Exertion (RPE) scale has been validated for decades as a reliable proxy for physiological intensity. Our 0–10 mapping uses a linear 2% pace adjustment per effort point:
For a runner with a 3:30 goal (8:00/mi avg), effort 6 = ~7:50/mi and effort 4 = ~8:10/mi. These small adjustments compound over 26.2 miles, and a coach can use them to sculpt negative splits, ease athletes through tough sections, or plan a strong finish.
Based on: Borg (1982) "Psychophysical bases of perceived exertion"; Foster et al. (2001) "A new approach to monitoring exercise training"
See exactly what weather conditions looked like on race day for the last decade so you can train for the likely conditions, not just hope for the best.
We pull real historical weather data from the Open-Meteo Archive API for your race's exact location and date. You'll see average highs, lows, wind, humidity, and rain probability, plus drill into each individual year for details.
This helps you make informed gear decisions (singlet vs. arm sleeves?), practice in similar conditions, and set realistic goals months before the race.
Mark exactly which miles you'll take nutrition with a single click. Fuel stops appear on the course map, in your splits table, and on your exported race plan.
Click the + button in the Fuel column of your splits table to toggle a fuel stop at any mile. The 🍊 icon appears on the course map at that location, and carries through to your PDF export.
Advanced users can auto-populate fuel stops from the Nutrition Calculator, which also adds detailed product/calorie info to each marker.
Start planning your next race with science-backed tools, for free.
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