I wanted to experimentally verify the step frequency’s (SF) dependence on Body Mass (BM). It appears in an equation I use to estimate leg-stiffness (kleg) for scenarios that I run through the model.

The expression is for the frequency of a mass bouncing vertically on a spring. This is similar to a subject running in-place with close to zero aerial phase.

The equation,


implies that if the BM increases, the SF should decrease according to 1/SQRT(BM).

If a subject while running very slowly, adds 20% to their BM using a weight jacket, then their step frequency should decrease by SQRT(1/1.2) or 8.7%. .

I have tried this myself, but I don’t have access to a weight jacket. I could only hand-hold an additional 10% of my BM while I ran slowly. Then, my SF dropped by 3%; I expected it to decrease by 5%.

I have looked for research on this issue, but I could not find any. Has anyone ever worked in this area? Or, are there any published articles on this topic?