Strava vs Garmin Race Predictor – the search term getting traction on my site – perfectly captures the runner’s conundrum. Garmin’s race predictions are bold (some might say absurd), while Strava’s are cautious, grounded in historical effort. But neither truly reflects the reality of marathon training after 50 or even after 60. That’s why I go to the Plus50Fit Predictor: a grounded, training-data-driven middle path.
In this post, I compare Strava, Garmin, and Plus50Fit race predictors using data from my training week of August 18–24, 2025.
Strava’s predictor, powered by Athlete Intelligence, leans on historical efforts. The result? Conservative but believable numbers. My marathon estimate just dipped to 5:09:35, reflecting my long runs and tempo efforts without overpromising.
Garmin’s predictor is based on VO₂ max and recent training intensity. While useful for short distances, it tends to ignore long-run durability and age-related adaptation. Case in point: Garmin currently believes I’m headed for a 3:23:16 marathon. Let’s just say that’s “fantastically optimistic!”
The Plus50Fit Predictor
This is where I bring in my own data. Using metrics like rTSS vs hrTSS, Pa:HR, IF (pace and HR), EF (Efficiency Factor), and VAM, “Coach” has built a more realistic model.
Based on the week of Aug 18–24, 2025 (Progression Run | Easy Run | Marathon Pace Efforts | Spicy Easy | Long Run), here’s what the Plus50Fit Predictor says:
| Predictor | 5K | 10K | Half Marathon | Marathon | Notes |
| Strava | 27:13 | 57:49 | 2:15:30 | 5:09:35 | Grounded, conservative |
| Garmin | 21:16 | 44:06 | 1:37:42 | 3:23:16 | VO₂ max optimism |
| Plus50Fit | ~26:45 | ~55:50 | ~2:03:00 | ~4:33:00 | Based on long-run durability + MP workouts |
This “third voice” doesn’t overshoot like Garmin, nor undercut like Strava. It accounts for how I’m actually performing across sessions, especially the long run and MP intervals, which are key marathon predictors.
What This Means for My Marathon
The gap between Garmin, Strava, and Plus50Fit illustrates why race prediction is both fascinating and flawed. Numbers can’t capture fueling, fatigue, or mindset on race day. But for me, the Plus50Fit Predictor feels closest to reality as I aim toward the TCS Toronto Waterfront Marathon this October.
Conclusion
- Garmin = dreamer’s algorithm.
- Strava = cautious analyst.
- Plus50Fit = grounded coach.
I’ll keep tracking all three predictors as my training builds. And in October, the real test will come when the clock stops at the finish line.
Related Post: Garmin vs Strava Race Predictions
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