Research recommends using a 30-day reference period when comparing long runs. Changing this value may reduce the accuracy of the distance ratio.

Frandsen et al. (2025) — How much running is too much? (Br J Sports Med.)

Long Run Planner

Plan a safe long run based on your recent longest session from the past 30 days (reference period).

Source: Frandsen et al. (2025) "How much running is too much?" PMC12421110 Br J Sports Med.

Quick Start

Option 1: Connect to Intervals.icu

1. Enter Athlete ID and API Key.
2. Set the risk window and how many days to fetch.
3. Click Fetch to load recent activities.

Option 2: Manual Entry

• Enter your longest run distance.
• (Optional) Enter your average pace.

Controls

• Use the unit toggle in the top bar to switch km/mi.
• Reference period (days) sets the comparison window for longest run and distance ratios. Research recommends 30 days.
• Days to fetch controls how many recent workouts are loaded from Intervals.icu.
• The slider sets your target increase and updates risk guidance.
• The suggested run and timeline update as you change inputs.

Output

• Gives you your suggested next longest run distance.
• (Optional) If avg. pace is provided it will also compute your est. duration.

Push to Intervals.icu