Processing Voltage Spike

    I am currently working on a MATLAB code that analyzes voltage from a force plate. A track athlete's force during a jump is plotted in volts, and my task is to filter the voltage within MATLAB. I have tried filtfilt, a zero lag butterworth, and a moving average function, but the problem is on impact. On impact the impulse is too high for an accurate butterworth, the filtered data overshoots the raw data graph. I am wondering if you have a suggestion that could help. I have heard that a zero-lag critically damped butterworth filter would be ideal. What do you think? Is there a resource that you know of that could help me?

[Dr. Seis]

The raw data essentially represents the "full" wave spectrum (as best the device can measure). This means that waves at different frequencies will constructively and destructively interfere with each other. It is possible that by filtering to a specific frequency band, you are removing signal that was destructively interfering with the signal associated with the frequency band of interest. If this is the case, then it is possible that the filtered result has amplitudes greater than the raw result.

Why aren't you removing the instrument response and converting from volts to physically tangible units?