Canary in the Coal Mine

Back in the day coal miners used to take caged canaries into the mines they were working.   Dangerous gases that couldn't be detected by miners such as methane or carbon monoxide would kill the canaries before the men and thus give them a warning of danger.  

Lately, I've viewed the Tensor Fascia Latae as a canary type of muscle.  This thin strip of a muscle is situated between the sartorious and glute med. and comes off the anterior superior iliac spine.   It's role is to essentially tense the fascia of the leg.  This includes the Iliotibial band and crural fascia in the calf.  

It will contract strongly when the opposite leg leaves the ground to help stabilize the pelvis.  This along with the tensioning the fascia is most likely it's primary role.   It contributes to hip internal rotation, hip flexion, hip abduction and hip extension.   Yes you read that right, hip flexion and extension.  When the leg is on the ground it assists the glute max (an extensor) with stabilizing.  It contributes to medial tibial rotation.  

With so many roles, if a primary muscle isn't doing it's job, this muscle tends to get short and have abnormal tension in it.  While it doesn't give a direct indicator of what primary muscle isn't working,  it suggests to me to that something in the hip isn't working like it should and needs investigation.