Training Load Monitoring
Uploading your weekly training files isn't just about record-keeping — it's a powerful tool for preventing overtraining and injury. The acute-to-chronic workload ratio (ACWR) compares your recent training load (last 7 days) to your chronic average (last 28 days). An ACWR between 0.8 and 1.3 is the 'sweet spot' associated with fitness improvement and low injury risk. Above 1.5, injury risk increases sharply — this typically happens when athletes dramatically increase training volume after illness, vacation, or a taper period. By uploading files weekly, you can track this ratio over time and catch dangerous load spikes before they cause problems. Other metrics to watch: total weekly duration should generally not increase by more than 10% from week to week (the widely-cited '10% rule'), and every 3–4 weeks should include a recovery week with 30–40% volume reduction. Heart rate data from your FIT files provides additional insight — if your average heart rate for the same pace is gradually increasing over weeks, you may be accumulating fatigue and need more recovery. All processing happens in your browser, so your training data stays completely private on your device.
How to Use the Weekly Training Log
Export your activity files from your device or app, then drop them all at once onto this tool. You can mix file formats — it handles FIT (Garmin, Suunto, Wahoo), GPX (universal GPS standard), and TCX (Garmin legacy format) in a single upload.
Exporting Activities from Common Apps
- Garmin Connect: Open activity → ⋯ → Export Original (FIT file)
- Strava: Open activity → ⋯ → Export GPX
- Suunto App: Open activity → Share → Export as FIT
- Wahoo Elemnt: Activities sync as FIT to your Wahoo account or Strava
Why Training Load Matters
Tracking weekly totals — especially the consistency of volume and elevation — helps you apply progressive overload safely. A common guideline is to increase weekly distance by no more than 10% per week. Sudden spikes in load are the primary predictor of overuse injuries in endurance athletes.
Key Weekly Training Metrics Explained
A weekly training summary is more than a raw mileage total. When you review your files after every training block, you should look at four core numbers together: total volume (distance and time), total elevation gain, intensity distribution, and training consistency. Together these tell you whether your week built fitness or quietly planted the seeds of an overuse injury.
Volume: Distance, Time, and Elevation
Total distance is the headline number, but total time is often more useful — it normalises across sports. A 40-minute swim and a 40-minute run contribute equally to cardiovascular load even though the distances are incomparable. Elevation gain matters most for mountain runners and cyclists: 60 km with 2,000 m of climbing is a very different week from 60 km on flat roads. Tracking all three together prevents you from gaming one number while underestimating overall load.
Intensity Distribution: Hard vs. Easy
The polarised and pyramidal training models both agree on one thing: most endurance athletes do too much work in the "grey zone" — moderate intensity that is too hard for easy recovery but too easy to drive strong adaptation. As a rough guideline, 75–80% of weekly time should be genuinely easy (conversational pace, low heart rate), with only 15–20% at a higher intensity. Heart rate data from your FIT files helps you audit this split. If your average heart rate across the whole week is creeping up week over week at the same perceived effort, that is a sign fatigue is accumulating.
The 10% Rule and Acute:Chronic Workload Ratio
Two widely cited guidelines help athletes ramp training volume safely. They are not hard physical laws — individual responses vary — but they provide sensible guardrails.
The 10% Per Week Rule
The 10% rule states that you should not increase your total weekly training load by more than 10% from one week to the next. If you ran 40 km last week, cap this week at 44 km. The rule is simple and easy to apply, which explains its popularity, though research suggests it is a rough heuristic rather than a precise threshold. Some athletes can handle larger jumps; others cannot. The bigger insight is the direction: sudden spikes — doubling volume after illness or a taper — are the primary pattern seen in overuse injuries, regardless of the exact percentage.
Acute:Chronic Workload Ratio (ACWR)
The ACWR compares your recent training load (the acute load, typically the last 7 days) with your longer-term fitness baseline (the chronic load, typically a rolling 28-day average). The ratio indicates whether your current week is within a range your body is prepared for. A ratio between roughly 0.8 and 1.3 is often described as a training "sweet spot": you are doing enough to build fitness without shocking the system. Ratios above 1.5 have been associated with elevated injury risk in several studies, though the relationship is not perfectly linear and the research is ongoing. The concept is borrowed from sports science and popularised by researchers like Tim Gabbett — present it as a practical guide, not a precise calculator output. The core principle is sound: consistency beats sudden surges.
Reading Weekly Trends Over Time
A single week's data is a snapshot. The real value of a training log comes from comparing snapshots over 4–8 weeks. A well-structured training block typically follows a build-build-build-recover pattern: three weeks of gradually increasing load followed by a recovery week with 30–40% volume reduction. This pattern allows your body to absorb the training stress, reduce accumulated fatigue, and come back stronger.
Build Weeks vs. Recovery Weeks
In a build week, you push volume or intensity slightly beyond the previous week. Your total distance or time goes up, your quality sessions feel more demanding. In a recovery week, you back off deliberately — not because you are tired (ideally), but because recovery is where adaptation happens. Skipping planned recovery weeks is one of the most common mistakes amateur athletes make: they feel good and keep pushing, accumulating fatigue that compounds invisibly until a forced rest — usually injury or illness — arrives.
A Worked Example: Summarising Five Runs
Imagine a week with five running sessions logged as FIT files. Monday: 8 km easy, 42 min, 80 m gain. Wednesday: 12 km with 4×1 km intervals, 62 min, 120 m gain. Thursday: 6 km recovery run, 38 min, 50 m gain. Saturday: 20 km long run, 1 h 55 min, 350 m gain. Sunday: 5 km shakeout, 28 min, 40 m gain. Upload all five files and the weekly totals become: 51 km distance, 5 h 25 min time, 640 m elevation gain, 5 activities. If the previous week was 46 km, this represents an 11% increase — right on the edge of the 10% guideline, acceptable if the athlete is healthy and the prior week was not already a peak. If the previous week was only 30 km (a return from travel), the same 51 km would be a 70% spike — a meaningful red flag worth noting.
Common Training Log Mistakes to Avoid
Ramping Volume Too Fast
The most frequent injury pattern in recreational runners is a rapid return to high volume after a break — a holiday, illness, or taper period before a race. Two weeks of low volume feels like nothing, but your chronic load baseline has dropped. Jumping back to your previous peak treats your body as if that baseline is still there. Instead, plan a 2–3 week ramp back to your previous level before continuing to build.
Grey-Zone Training
Moderate-intensity training — the pace that feels "comfortable but purposeful" — is enjoyable and produces some fitness, but it accumulates fatigue faster than truly easy running while generating less adaptation than genuinely hard efforts. Many recreational athletes spend 70–80% of their training in this middle zone. Review your heart rate data: if almost every session shows an average HR in the 140–160 bpm range, you are likely in the grey zone. Try making your easy days easier and your hard days harder.
Ignoring Rest Weeks
Planned recovery weeks feel like wasted time, especially when you feel good. But fatigue is cumulative and often masked by adrenaline and motivation. Build a deliberate recovery week every 3–4 weeks: cut volume by 30–40%, keep a small amount of intensity, and prioritise sleep. Athletes who follow this pattern consistently tend to arrive at race day fresher and perform better than those who train hard every single week.
Frequently Asked Questions
How many weeks of data should I track?
For the acute:chronic workload ratio to be meaningful, you ideally need at least 4 weeks of consistent data. Most coaches recommend reviewing 6–12 weeks of history when assessing fitness trends and planning the next training block. This tool summarises any files you upload, so you can run separate weekly uploads and note the totals in a simple spreadsheet to track multi-week trends.
Does the tool calculate training stress scores or TRIMP?
Currently the tool reports raw metrics — distance, time, elevation, and average heart rate — rather than derived stress scores like Training Stress Score (TSS) or TRIMP (Training Impulse). TSS calculations require your functional threshold power or lactate threshold heart rate as inputs, and those vary significantly between athletes. Raw time-in-zone data from your heart rate is a good proxy: if you are accumulating many hours above threshold each week, load is high regardless of what any single number says.
My average heart rate varies a lot between sessions — is that normal?
Yes, and it is informative. Heart rate is influenced by fatigue, heat, humidity, hydration, caffeine, sleep quality, and mental stress. A higher-than-expected HR on what should be an easy day is often an early signal of accumulated fatigue or the early stages of illness. Over several weeks, a rising average HR at the same perceived effort is a more reliable fatigue indicator than any single session.
Can I use this tool for cycling, swimming, or strength training?
Yes. FIT, GPX, and TCX files from cycling computers and multisport watches record the same core fields regardless of sport. The tool reads sport type from the file and displays it in the activity table, so mixed-discipline weeks are supported. Note that comparing distance across sports is not meaningful — a 20 km run and a 20 km cycle are very different loads. For cross-training weeks, focus on total time as your consistent volume metric rather than total distance.