[iamacyborg]

This could be pretty easily quantified if you look at how world records have progressed over the years.

Better fitness technology leads to faster times across the board.

[nradov]

Technology has also improved in many other areas: exercise physiology knowledge, nutrition, aerodynamics, lab testing, PEDs, bouncy shoes, etc. It's tough to isolate how much of the total improvement was caused by fitness trackers.