What is the Regression Rate? The regression rate measures the percentage by which your per-mile pace slows when you double the race distance. A rate of ~6.5% is considered natural. A higher percentage indicates a need for more base, strength, and strength endurance work to build fatigue resistance. A lower percentage suggests a need for more speed, speed endurance, and potentially biomechanical work.

The 4×1600m running test provides a predicted 5K pace by averaging your four rep times. Alternatively, if you already know your current 5K race time, enter it directly.

Predictions use your 5K time and regression rate to estimate paces at various distances. The formula: Time = 5K_Time × (Distance_Ratio) ^ (1 + Regression_Rate). A higher regression rate means more pace degradation over distance.

How zones are calculated: Your LT2 (Lactate Threshold 2) pace is estimated as the pace you could sustain for a continuous effort — 35 min for Age-Group, 45 min for Performance, or 60 min for Elite athletes. LT1 is then set as a percentage of LT2 speed. Zones are distributed across these thresholds.

These goal times are derived from your 5K fitness and represent the paces you should target during speed and speed endurance interval sessions. They progress from longer repetitions (building speed endurance) down to shorter reps (developing raw speed and neuromuscular power).