Intervals.icu vs EffortSignal
TL;DR
EffortSignal is a good fit if you plan your own cycling or running training and want to build workouts visually, reuse training weeks, and compare recent efforts with your own history. You can keep your calendar, readiness, training load and activity analysis together, then open the details when something changes.
Intervals.icu may suit you better if you coach several athletes or want more custom analysis tools, such as custom data fields, saved comparison sets and activity charts aligned by time or distance. Both products have a workout builder and interval analysis; the differences are in how you use them and how much you can customize.
Intervals and activity comparison
| What you want to do | EffortSignal | Intervals.icu | Keep in mind |
|---|---|---|---|
| Find intervals in a recording | Five detection modes: steady power, steady pace, steady HR, climbs and repeated route sections. Up to 60 candidates per search. | Automatic interval detection. | Each EffortSignal mode needs the matching sensor or route data. The same five modes and limits are not confirmed for Intervals.icu. |
| Review and edit intervals | Recorded laps, manual ranges and detected intervals, with a table and Breakdown cards. | 70+ interval metrics and custom fields. | The available fields and editing steps differ between products. |
| Find similar intervals in past activities | Automatic search, up to 50 results and three per activity. Pro. | Search by interval intensity and duration. | Automatic matching and searching by criteria are different ways to find a comparison. |
| Compare whole activities | Up to five of your activities, including the starting activity; metric table and CSV export. Free. | Compare multiple activities, including activities from different athletes. | EffortSignal compares your own history. Intervals.icu also supports comparisons between athletes. |
| Compare charts | Power and heart-rate duration curves. | Overlay activity charts by time or distance and shift them to line up. | Use Intervals.icu if aligning the recorded traces is essential to your comparison. EffortSignal’s curves compare sustained efforts over different durations. |
| Save a comparison for later | Saved, named comparison tabs are not available in the current comparison dialog. | Saved comparisons and multiple tabs. | Intervals.icu lets you return to saved comparison sets. |
| Compare with a separate FIT file | One temporary FIT file up to 64 MiB, without adding it to your history. Pro. | This exact workflow is not confirmed in the linked official documentation. | Importing a file into your history is different from comparing it temporarily. |
| Find similar whole activities | Automatic same-sport search, up to 50 matches. Pro. | Search by name, hashtag and interval criteria. | The products use different search and matching tools. |
| Track a personal route section | Private Segments saves a section, checks travel direction and finds later passages. Free includes three tracked segments. | An equivalent saved personal-segment workflow is not confirmed in the reviewed documentation. | A route map alone does not mean the product tracks repeated passages automatically. |
Workout creation and calendar planning
| What you want to do | EffortSignal | Intervals.icu | Keep in mind |
|---|---|---|---|
| Build a structured workout | Visual Workout Planner, with targets suited to the sport. | Text-based Workout Builder. | Choose the editing style you prefer. Both create structured workouts. |
| Drag a block to change it | Drag duration and intensity handles in the power/HR editor; use a separate handle to reorder steps. | The documented editor focuses on writing workout steps as text. | Equivalent dragging of individual blocks is not confirmed for Intervals.icu. Dragging a planned workout on a calendar is a separate action. |
| Set power targets | Watts, % FTP or zones, with one target model per workout. | Watts, % FTP, % modeled MAP and zones. | Modeled-MAP targets are not available in EffortSignal’s builder. |
| Set heart-rate, pace or other targets | Sport-specific values or zones; RPE for supported strength and other workouts. | Heart-rate and pace percentages/zones, plus cadence. | EffortSignal does not offer cadence as the main workout target, arbitrary custom targets or target ranges. |
| Create repeats | Repeat groups, with 1–99 repetitions, 1–20 steps per group and a 2,000 expanded-step limit. | Exact repeat controls and limits are not confirmed by the reviewed builder page. | The published EffortSignal limits should not be assumed to apply to Intervals.icu. |
| Reuse a workout | Library, tags, favorites and duplicates. | Workout library in the calendar. | In EffortSignal, scheduling saves a copy: later library edits do not rewrite that plan. The same behavior is not confirmed here for Intervals.icu. |
| Reuse a week or training plan | Seven-day templates, up to 100 placements, with Add/Replace and conflict review. | Training plans for multiple athletes, with drag-and-drop and bulk calendar application. | EffortSignal’s weeks are for your own calendar. Intervals.icu also serves multi-athlete planning. |
| Move a planned workout | Calendar dragging and explicit move actions. | Drag-and-drop calendar. | Moving a plan in EffortSignal does not move the completed activity. |
| Compare a plan with what you completed | Match a recording and review execution. Basic totals are Free; detailed performance evaluation is Pro. | The exact matching and evaluation steps are not confirmed in the reviewed pages. | Check the detailed review you need before switching products. |
| Export workout files | FIT, plus ZWO/MRC/ERG for eligible cycling-power workouts. | ZWO, FIT, MRC and ERG import/export. | Check the supported sport, target and destination device, not just the file extension. |
| Send workouts to a device provider | Garmin and Wahoo, with sport and target limits. Wahoo needs a scheduled workout. | Device synchronization. | Applying a week in EffortSignal creates calendar plans; it does not send them to devices. Actual device downloads were not tested for this comparison. |
Other differences to consider
Training numbers may differ. EffortSignal explains its TRIMP-based fitness, fatigue and form, Weighted Power, PSS and Readiness. Products can use the same metric name but handle pauses, missing data or starting values differently. Do not expect every number to match after switching.
Custom analysis and coaching are stronger reasons to consider Intervals.icu. Its Activity Timeline supports custom fields, custom data streams and spike correction; its Training Plan Editor supports multiple athletes. EffortSignal offers its built-in charts and metric settings and a personal calendar. A group event in that calendar is not a coaching-management feature.
Check the connection you need. Historical Garmin import is currently limited; see Device Sync for the current status. Provider support can differ by direction, sport and device. This comparison does not confirm equivalent native iOS features or publicly available EffortSignal route-planning tools.
Check which actions need Pro. EffortSignal’s manual comparisons and basic planning are Free; automatic similarity, external FIT comparison and detailed execution review have separate Pro rules. See Pricing for current Early Access terms. Intervals.icu’s current subscription limits were not checked here.
About this comparison
Checked September 10, 2026, using EffortSignal 0.1.13 with demo data and Intervals.icu’s official pages linked above. We did not test Intervals.icu’s signed-in workflows or download workouts onto physical devices.
“Not confirmed” means the available information did not answer that specific question. It does not mean the feature is missing. Follow the linked product details for limits that matter to your training.
Content checked September 10, 2026 · EffortSignal release 0.1.13