Reducing noisy data from non normal distribution of data with std deviation?
First, good practice to raise validity concerns here when removing outliers and/or filtering data. This may have strong affects of validity of results. An intro is here: When to remove outlier in preparing features for machine learning algorithm .

Second, is it possible to address the small dataset problem -- Can you collect more data? Redefine the population to produce more data? Use another data set that is similar in developing the model?

Lastly, this seems to be a filter problem, to get started on a solution, check MATLAB documentation for filters.

If the results are going to be used anywhere, probably a good idea to document all of your decisions and the first two concerns. Absent much more detail, experience says there is a pretty high risk to any conclusions based on this model.