Originally Posted by gregf83

It's not perfect but the W' component of the critical power model of Monod Scherrer provides a reasonably close estimation of Anaerobic Work Capacity (AWC) measured in kJ. To measure requires a couple all-out efforts of different durations and you'll get your Critical Power, CP, and AWC values. If you ride all-out for one hour the AWC component gets spread out over the full hour and added to CP. If you sprint all-out for 30 Seconds the total power available is roughly CP + AWC/30.

You can read a little more here: Modeling the Expenditure and Recovery of Anaerobic Work Capacity in Cycling

Golden Cheetah will provide an estimate of AWC based on recent hard efforts.