Super Critical Power SCP
Maximal aerobic power MAP should not be confounded with the power that elucidates maximal oxygen consumption P-VO2max. In fact there is no such thing as a power that corresponds to VO2max because all power higher than Super Critical Power SCP will ultimately cause volitional exhaustion at VO2max. Let me first give credit to Michael Puchowicz MD from Veloclinic for first introducing the concept of SCP.
Let us clarify the relations between CP, SCP, MAP and VO2max with the help of the Power-Duration or MMP data of a top class WT cyclist over one full year. Because the CP model predicts a hyperbolic or 1/Time relation, we prefer to show these MMP data with the inverse of time on the x-axis.
The righgtmost points correspond to all out effort of 2 minutes while the leftmost points are for efforts of 1 hour.
The red data present the total power Ptot while the blue points present the aerobic power Pae that is obtained by subtracting the anaerobic contribution Pae = Ptot - W'/T
where T is the time of the effort and W’ is the anaerobic capacity of this particular cyclist, equal to 18,720 kJ
The difference between the red and the blue data is equal to the anaerobic power Pana
Both the total power and the aerobic power lower-left segments intersect the y-axis at the same Restore Threshold RT = 346 W. At this power value the inverse of time is zero, thus the sustainable time is infinitly long. All power below RT can be sustained undefinitely long and is purely aerobic in nature.
With increasing power demand both total power and aerobic power Pae increase but Pae saturates at 452 W and at sustainable time 740 s (see vertical dotted line). At even higher power demands the aerobic power Pae no longer increases which means that the real Maximal Aerobic Power MAP = 452 W
The total power does not saturate because the anaerobic contribution still increases. The intersection of the low-left and the high-right red segments is at the same sustainability 740 s, but at the total power equal to 478 W.
This intersection of the 2 red total power segments identify the Super Critical Power at 478 W and sustainable time 740 s
The intersection of the 2 blue aerobic power segments identify the Maximal aerobic Power MAP
The zero-extrapolation of the total power is the Critical Power CP. It is equal to MAP at 452 W. CP is conceptually equal to MAP.
The slope of total power above SCP is equal to the Anaerobic Capacity W’ = 18,720 kJ
In short ; The maximal aerobic power MAP = 452 W is reached at the total power at SCP = 478 W and this effort can be sustained during 740 s. When riding at SCP the anaerobic contribution is equal to (478 - 425) = 53 W or 11 % of total power.
SCP is the lowest power where the aerobic contributiin is MAP and that elucidates VO2max
Many aurhors consider CP to be the golden standard for performance. CP indeed it is very important bercause it identifies the highest aerobic power but it is not the threshold between the hard and severe exercise zones (or between slow death end fast death exercise). SCP is the real threshold.