Track your Chronic Training Load (CTL), Acute Training Load (ATL), and Training Stress Balance (TSB) across seasons. Balance high-intensity intervals with optimal recovery.
Chronic Training Load (CTL) is an exponentially weighted 42-day rolling average of your daily Training Stress Score (TSS). It models historical training volume and aerobic stamina.
A rider with a CTL of 40 has an aerobic base suitable for 2-hour club rides, while competitive racers targeting Gran Fondos or stage races typically build toward a CTL of 75 to 105.
Acute Training Load (ATL) is an exponentially weighted 7-day rolling average of your recent stress. It reflects the immediate toll of recent hard intervals, pack rides, or century climbs.
ATL rises and falls quickly. A big weekend of riding will cause your ATL to spike, signaling temporary muscular soreness and central nervous system fatigue.
Training Stress Balance (TSB) is the difference between fitness and fatigue (TSB = CTL - ATL).
WattsUP bridges winter trainer workouts with outdoor summer rides. The Smart Engine reads your live TSB from your imported files and adjusts the interval intensity of your upcoming sessions:
When your TSB dips too low, the Virtual Cockpit dials back the wattage targets, swapping intense VO2 max intervals for aerobic flush sessions to protect your season progression.
A safe and sustainable ramp rate is 3 to 6 CTL points per week. Increasing CTL faster than 7–8 points per week sharply elevates the risk of overtraining, chronic illness, and tendon inflammation.
Yes. Your training load does not stop when the seasons change. Workouts completed in the WattsUP Virtual Cockpit combine seamlessly with GPX/FIT files recorded on the road, maintaining one uninterrupted 12-week load trend across the year.
TSS measures both workout duration and intensity relative to your FTP. An all-out 1-hour time trial at 100% of your FTP equals exactly 100 TSS. Two hours at 70% of FTP yields approximately 100 TSS as well.