Heart Rate
Heart rate is the number of heartbeats per minute (bpm). In training it serves as an indirect marker of intensity, fatigue and recovery state.
Definition
“Heart rate” is the number of heartbeats per minute, expressed in bpm (beats per minute). It describes how often the heart pumps blood into the circulation and rises with the oxygen demand of the working muscles.
In training, heart rate is an indirect marker of intensity. It does not measure the work performed but the body’s response to it. That is both its value and its limitation.
Why it matters
Heart rate responds to more than just the workload. Heat, dehydration, lack of sleep, caffeine and fatigue shift it up or down. Seeing different heart rates at the same power on two different days is therefore not a measurement error but information about the athlete’s state.
The coupling of heart rate and power is one of the most informative analyses. If power stays constant and heart rate rises, this is called cardiac drift. If heart rate at the same power falls over weeks, that is a sign of improved aerobic fitness.
| Method | Principle | Accuracy | Limitations |
|---|---|---|---|
| Chest strap | Electrical (ECG signal) | Very high, beat-accurate | Must be moist and in contact |
| Optical wrist sensor | Light (PPG) | Good during steady efforts | Lags during intervals, affected by cold, tattoos, movement |
| Optical upper-arm band | Light (PPG) | High | Fewer motion artefacts than at the wrist |
| ECG recording (diagnostics) | 12-lead electrical | Reference | Lab only |
For RR intervals, and therefore for heart rate variability, a chest strap is a prerequisite. Optical sensors do not deliver reliable RR data during movement.
How obseed measures it
obseed imports heart rate from your watch or sensor recording and evaluates it second by second. From this it derives time in heart rate zones, average and maximum values per session and segment, and the coupling to power and speed.
Zones are based on the stored performance parameters. Ideally the thresholds come from a metabolic or lactate test rather than an age formula. Heart rate reserve additionally allows intensity to be expressed relative to the individual range.
Example
An athlete rides two hours steadily at 200 W. In the first hour her average heart rate is 142 bpm, in the second 151 bpm.
drift = (151 − 142) / 142 = 6.3 %Drift above 5 % at constant power points to aerobic endurance that is not yet sufficient for this duration, or to heat and fluid deficit. If she repeats the same session six weeks later at 143 and 146 bpm, drift is only 2.1 %. The coupling of heart rate and power has become more stable, a clear sign of adaptation in base endurance.
Categories
- Diagnostik
- Technische Begriffe
- Trainingsaufzeichnung
- Trainingssteuerung