Has this guy mentioned the fact that you should NOT be sitting like a couch potato for hours at a time? Part of your treatment should include basic ergonomics at the work place and please don't slouch using the laptop!!! Part of the problem is Posture. You don't mention how intense the mountainbike and road (racing?)bike activity is but that will probably be with a rounded back as well. AT 6'2'' you will be probably looking down at people most of the time and slouching your upper thorax, bad shoulder posture and so on. Focus only/primarily on the hamstrings is probably not going get you further. These sore quads would suggest to me that you are overdoing it somehow despite your statement that "when no serious exercise has been performed". Your back is rather telling you what it wants at the moment...less bent positions. I can't say this guy is doing it all wrong on the basis of your information, he may be doing stuff that you haven't mentioned that is OK. Have you checked on his qualifications etc? Have you been to any other specialists? There must be loads of good physios around, I think it may be time for a change. I can't diagnose online but you may well benefit from a Mackenzie regime for your back. And a serious look at "giving" real stability and well balanced muscles to your "core" first before taking away the hamstrings compensation "stability"