Well I play tennis and I've always had a problem with my quads (lactic acid build up), especially the past few weeks. I went to the trainer at my school and she said that I just needed to take creatine... only I don't think its legal in our high school league. My private coach has been begging me to see my doctor because its pretty serious... my legs (especially the right one) always tense up and get tight within like 5 minutes and stay that way until I stop. Any ideas?

Why haven't you gone to see the doctor? He's the only one who can determine if the problem is muscular, neurological, metabolic, or circulatory--all of which can mimic one another. If indeed it is just lactic acid buildup, then perhaps the advice given at the following website might prove useful.

http://av.rds.yahoo.com/_ylt=A9ibyK3jjotF.MEAjBVrCqMX;_ylu=X3oDMTBvdmM3bGl xBHBndANhdl93ZWJfcmVzdWx0BHNlYwNzcg--/SIG=12fti1j5h/EXP=1166860387/**http%3a//www.earthclinic.com/CURES/poor_circulation_legs.html