Session
A session is one complete recorded training unit, from starting the watch to saving the file, uploaded as a single dataset for training load analysis.
Definition
A “session” is a single, fully recorded training unit. It begins when recording is started on the sports watch or bike computer and ends when the activity is saved. The saved object, usually a FIT file, is then uploaded for analysis.
A session contains one-second data (heart rate, power, pace, GPS, altitude, cadence), laps and segments, and metadata such as sport profile, device, and start time. It is the smallest unit from which load metrics are computed.
Why it matters
Everything said about training load is built on sessions. TSS per session adds up to weekly load, and weekly load feeds Chronic Training Load and Acute Training Load. If a session is missing or faulty, the whole chain is distorted.
Typical problems arise at the edges: the watch keeps running after the workout, recording starts only after the warm-up, or one workout is accidentally saved as two files. The wrong sport profile also has consequences, because it determines the control metric and therefore the load calculation.
| Source of error | Effect |
|---|---|
| Recording continues after the workout | Averages drop, duration rises, TSS is distorted |
| Two files for one workout | Normalized Power and NGP computed separately, load underestimated |
| Wrong sport profile | Wrong zones and control metric, IF and TSS unusable |
| Sensor dropout | Power missing, fallback to heart rate required |
How obseed measures it
obseed imports each session as its own dataset and computes duration, distance, Normalized Power or Normalized Graded Pace, Intensity Factor, and TSS from it. Zone distribution is calculated against the thresholds from metabolic testing, not against an estimated FTP.
On import obseed checks plausibility: does the duration fit the sport profile, are there long stretches without movement, is sensor data missing. Anomalies are flagged so the session can be corrected or excluded from the load calculation before it flows into CTL and ATL.
Example
A cyclist uploads a session with the following figures. Her VT2 from spiroergometry is 250 W.
| Metric | Value |
|---|---|
| Duration | 1:45:00 h |
| Distance | 52.3 km |
| Average power | 178 W |
| Normalized Power | 205 W |
| Intensity Factor | 205 / 250 = 0.82 |
| TSS | (6300 s × 205 × 0.82) / (250 × 3600) × 100 ≈ 118 |
The session contributes 118 points to the weekly load. Had the watch kept running for another 20 minutes while she stood still, average power would have been 150 W, NP around 196 W, and TSS about 128, despite identical training work. Clean session boundaries are therefore not a formality but the foundation of load management.
Categories
- Trainingsaufzeichnung
- Technische Begriffe