Effect of SFR training

Effect of SFR training
- SFR training improves 40km TT time.
- It seems odd. There isn't any improvement of torque. However, Vo2Max is improved.
- It seems that almost all the performance enhancement is brought by improvement in the Vo2Max.
- If so, why not they cannot improve 40km TT time by doing "pure" Vo2Max work? Which work is more effective?