Fig. 4

Five post-exercise readings superimposed on one another to illustrate the principal of T₅₀. Five post-exercise readings are seen above. T₅₀ [sec] is the time needed to return to 50 % of maximal flow. This can be determined within the NIVP3 software by identifying the trace whose flow rate is closest to half the MFR and then by working out the exact time within that trace that the flow rate reached T₅₀. In this case, the MFR is 7.88 %/min so T₅₀ is found when flow drops to 3.94 %/min. Flow drops to this level around 7.5 s into the fourth reading which makes T₅₀ 37.5 s