GoldenCheetah 進階指標 Advanced Metrics

W' Balance — 無氧功能儲備追蹤

W prime W' represents the finite anaerobic capacity available above critical threshold. When output exceeds the critical CP level, W' depletes at a rate proportional to how far above CP the effort sits. When effort drops below CP, W' recovers at an exponential rate. Monitoring W' Balance in real time during a ride — or retrospectively from a completed Strava activity — reveals how close an athlete came to complete neuromuscular exhaustion and how quickly recovery occurred between hard efforts.

The three-parameter critical CP model used by TCU fits each athlete's individual maximal efforts to derive personalized CP and W' values, resulting in more accurate predictions than population-average estimates.

Critical Power CP Model 臨界功率模型

Critical Power CP is the highest sustainable aerobic output — conceptually similar to FTP but derived mathematically from multiple maximal efforts at different durations. The two-parameter hyperbolic model fits a curve through best efforts at 3, 5, 10, and 20 minutes to calculate both CP and W'. Adding a third parameter, anaerobic metabolic rate, improves accuracy at very short durations below 2 minutes. These values are updated automatically as new maximal efforts appear in the Strava activity history.

Efficiency Factor EF 效率因子

Efficiency Factor EF is calculated as Normalized Power divided by average heart rate for the same effort. A rising EF over consecutive aerobic sessions at similar intensity indicates improving cardiovascular efficiency — the heart is delivering more mechanical output per beat. EF is most meaningful for long steady-state rides where heart rate is stable. Comparing EF for the same route across different seasons provides a sensitive measure of aerobic fitness gains independent of external conditions.

Additional Advanced Metrics 其他進階指標

Normalized Power NP applies a fourth-power weighting to watt output, calculating the constant-effort equivalent of a variable-paced ride. Training Stress Score TSS combines NP, IF, and session duration into a single comparable load unit. Intensity Factor IF expresses session intensity as a fraction of FTP. Peak Pedaling Cadence and torque effectiveness metrics are also available for athletes with cadence sensor data. All metrics are calculated locally from raw Strava activity files without external API calls.