Carl-
I’m not aware of an in vivo non-treadmill, in-competition, fine wire needle EMG on the Psoas using sub 10 sprinters (just in case anyone wanted to ask that question to refute my EMG assertions). That said, there’s plenty of surface EMG studies on adductor magnus and rectus femoris. Both of which act as hip flexors (and given the kinematics of swing phase are obviously doing this rather than than adduction or knee extension respectively following toe off) The adductor magnus is likely also counteracting the external rotation of the hip from sartorius and the major TFL. And the work of Nachemson who has used fine wire EMG, suggest psoas would have the same role in running. And since we know muscles rarely act in isolation, I think it’s safe to say if these other hip flexors are lit up, the Psoas likely is too.
I increasingly use drills the same way you mentioned….strength and mobility but I still require athletes to match a technical model to learn body awareness and my cueing system.
ELITETRACK Founder