The statistical question is whether you would have done those exercises regardless of whether you consulted a physiotherapist. If you would have done those free weights exercises anyway, then it's unreasonable to credit the physio with your recovery; if you wouldn't have done them of your own accord, then it's reasonable to credit the physio even though the precise causal mechanism wasn't what we would expect. We're not trying to address philosophical questions, but find out whether particular treatments have a meaningful effect.