I recently came across this company
www.saris.com that has a product called "Power Tuned" where they have a device measures the usual: heart rate and cadence, but also records up to 15 hours at 1-second recording rates, records unlimited intervals, and measures torque you apply to pedals (Power).
They have it for bikes (hub on back wheel) and a indoor group cycling bikes called Cycle Ops.
No, I am not spamming or selling a product...I truly want to know if anyone has used or heard of product