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

Estimate a safer next long run using your recent longest run and evidence-based risk zones.

Source: Frandsen et al. (2025), Br J Sports Med, PMC12421110

Quick Start

Option 1: Connect to Intervals.icu

1. Enter API key (required) and athlete ID (0 for yourself).
2. Set Days to fetch.
3. Click Fetch.
4. Review the suggested distance and adjust with the progression slider.

Option 2: Manual Entry

1. Enter Longest Run (required for manual mode).
2. Optionally enter Avg pace to get an estimated duration.
3. Review the suggested distance and adjust with the progression slider.

Required Inputs and Choices

• No output is shown until you provide run data (fetch or manual distance).
• Reference period (days) controls the comparison window for longest run.
• Changing the default 30-day reference period prompts a one-time confirmation.
• Use the progression slider to set your target change (-25% to +100%).

Workout Builder / Push

• Workout text auto-generates from the current suggestion.
• API Key, Athlete ID, and Date are required to push to intervals.icu.
• The risk indicator shows where your suggested increase falls relative to safe progression thresholds from the source study.
• If you already fetched from Intervals.icu, the workout panel reuses those credentials.
• Use Copy if you want to paste workout text manually instead of pushing.