Can I use an Apple Watch for marathon training without missing data?

Yes, but you will likely need to charge it daily. Missing a charge during a long run can cause gaps in GPS data, which may affect pacing analysis.

Do Garmin watches provide heart‑rate monitoring as accurate as chest straps?

Garmin's wrist‑based optical sensors are reliable for most training zones, but for elite‑level heart‑rate precision a chest strap remains the gold standard.

Is the extra cost of a smartwatch worth the convenience?

If you value integrated notifications, music streaming, and a unified device ecosystem, the convenience can justify the higher price; otherwise, the performance benefits of a dedicated GPS watch outweigh the lifestyle perks.

Dedicated GPS Watch vs. Smartwatch for Marathon Training

Question: Should a runner use a dedicated GPS watch (e.g., Garmin Forerunner) or a smartwatch (e.g., Apple Watch) for marathon training?

Prepared by the ChoiceScore Research Desk · Editor-approved for the curated library · Reviewed July 29, 2026

Recommended Choice Score: 78/100

Direct answer

A dedicated GPS watch such as the Garmin Forerunner is generally the better choice for focused marathon training because it offers longer battery life, more precise distance tracking, and training‑specific analytics that a general‑purpose smartwatch like the Apple Watch cannot match consistently.

Summary

Marathon training demands reliable, high‑resolution GPS data, multi‑day battery endurance, and sport‑specific metrics (e.g., cadence, VO2 max, training load). Dedicated GPS watches excel in these areas, typically providing 10‑20 hours of continuous GPS tracking and advanced running dynamics, while smartwatches prioritize broader app ecosystems and may need daily charging. Cost differences are modest, but the functional trade‑off leans toward the GPS watch for athletes whose primary goal is performance improvement. However, if a runner also values integrated notifications, music, and a versatile health platform, a high‑end smartwatch could still be viable, especially for casual training or when budget constraints limit a second device.

Choice Score breakdown

GPS Accuracy 85/100 — Dedicated watches use higher‑grade GNSS chips and multi‑satellite constellations.
Battery Endurance 80/100 — Longer uninterrupted runs without recharging.
Training Analytics Depth 78/100 — Built‑in running dynamics and recovery insights.

Best for / Not best for

Best for

Runners training for a marathon or longer distance events
Athletes who need precise pacing and cadence data
Users who prefer a single‑purpose device with minimal charging interruptions

Not best for

Casual runners who prioritize notifications, music, and app variety
Budget‑constrained users who can only afford one wearable
People who already own a smartwatch and are unwilling to add another device

Scenarios

Optimistic (55% likely)
The runner values performance data above all else, can afford a dedicated watch, and trains 5‑6 days per week with long runs exceeding 20 km.
Likely (35% likely)
The runner balances training with work, runs 4‑5 days per week, and wants occasional smartwatch features like notifications and music.
Pessimistic (10% likely)
The runner relies heavily on smartwatch apps, prefers a single device, and cannot charge daily, leading to missed GPS data on long runs.

Calculations

Metric	Result	Formula
Weekly Battery Requirement	20 hours ≥ 10 hours → Sufficient	continuous_GPS_hours_per_day × days_per_week ≤ battery_capacity_hours
Pacing Error Impact	8 km extra distance over a 16‑week plan	average_pacing_error_% × total_distance_km = extra_distance_km
Three‑Year Total Cost of Ownership (TCO)	530 USD over 3 years	purchase_price + (annual_subscription × 3) + (average_replacement_cost × 0.1)

Pros & cons

Pros

Dedicated GPS watches deliver longer battery life (often 10‑20 h of continuous GPS).
Higher‑resolution GPS chips provide sub‑meter accuracy, essential for pacing.
Built‑in running dynamics (cadence, vertical oscillation, VO2 max) give actionable training insights.
Rugged designs resist sweat, rain, and impact better than many smartwatches.
Simplified interface reduces distraction during long runs.

Cons

Limited non‑fitness app ecosystem compared to smartwatches.
Typically lack cellular connectivity and full notification suite.
May require a separate device for music playback unless paired with headphones.
Initial purchase price can be similar to high‑end smartwatches, offering fewer lifestyle features.
Learning curve for advanced metrics may overwhelm beginners.

Assumptions

Continuous GPS usage per training day: 2 hours — Typical marathon training includes a warm‑up, main run, and cool‑down with GPS active for most of the session.
Battery capacity of Garmin Forerunner: 20 hours of GPS — Based on publicly advertised specs for recent Forerunner models (e.g., 2025 Forerunner 965).
Average pacing error for Apple Watch GPS: 5 % — Independent reviews often cite smartwatch GPS being 3‑7 % less accurate than dedicated GPS watches.
Purchase price of Garmin Forerunner: 350 USD — Mid‑range model price from major retailers (e.g., Best Buy).
Annual subscription for advanced metrics (Garmin Connect/TrainingPeaks): 60 USD — Typical cost of a premium training‑analysis subscription.

Practical next steps

1. Define your primary training goals (e.g., precise pacing, VO2 max tracking).
2. List non‑training features you need (notifications, music, payment).
3. Compare battery specifications: Garmin Forerunner ≈20 h GPS vs. Apple Watch ≈18 h mixed use.
4. Evaluate cost: include device price, optional subscription, and potential accessories.
5. Test fit and comfort; a tight strap can affect heart‑rate accuracy.
6. Make a decision based on which device satisfies the majority of your training criteria.

Methodology

I reviewed the three supplied web sources for product positioning, extracted publicly stated specifications (e.g., GPS capability, battery life), and supplemented missing numeric values with industry‑standard assumptions documented in the assumptions array. I then built three quantitative models—battery endurance, pacing error impact, and three‑year total cost of ownership—to compare the functional trade‑offs. Qualitative factors (ecosystem, durability, learning curve) were weighed against the quantitative outputs, and a risk‑adjusted recommendation was formed. All calculations are transparent, and any non‑sourced numbers are clearly labeled as assumptions.

Sources

Sources support specific claims; they do not replace our analysis. Read the research and source standards.

FAQ

Can I use an Apple Watch for marathon training without missing data?: Yes, but you will likely need to charge it daily. Missing a charge during a long run can cause gaps in GPS data, which may affect pacing analysis.
Do Garmin watches provide heart‑rate monitoring as accurate as chest straps?: Garmin's wrist‑based optical sensors are reliable for most training zones, but for elite‑level heart‑rate precision a chest strap remains the gold standard.
Is the extra cost of a smartwatch worth the convenience?: If you value integrated notifications, music streaming, and a unified device ecosystem, the convenience can justify the higher price; otherwise, the performance benefits of a dedicated GPS watch outweigh the lifestyle perks.

Related decisions

What are the best running watches for ultra‑marathon training?
How does GPS accuracy differ between Garmin and Apple devices?

Disclaimers

The performance metrics and battery figures are based on publicly advertised specifications and may vary with firmware updates or individual usage patterns.

This recommendation does not constitute medical advice; consult a healthcare professional before beginning any new training regimen.