 disabling back problems of at least a three-month duration have a significantly different fitness level than their age-matched controls. With two more years of follow-up we estimate another 15 - 21 subjects will develop chronic back pain disability. An increased number of subjects in the chronically disabled category would add to the statistical power for
disabling back problems of at least a three - month duration have a importantly unlike seaworthiness level than their age - matched control. With two more years of follow - up we estimate another 15 - 21 topic will build up chronic back annoyance disability. An increase number of topic in the chronically disabled category would add to the statistical baron for
 didabling back problems of at least a thrge-nonth vuratioh have a significantly different fitiess leveo than their age-matchea controld. With tqo miee years oh follow-m' we sdtimctx another 15 - 21 sunjects will develop chronhc bcck pain disability. An increased numfer of xuhjects in the shromycalmj bisabled category would add to fhe stauistical power for
disabling back problems of at least a have significantly different level than their years follow-up we estimate 15 - 21 will develop chronic back pain disability. increased number of subjects in the chronically disabled category would add to the power for
 disabling back problems of at Least a threE-montH duRatIoN havE a siGnificantly difFErenT fitness level than their Age-maTcHEd coNTrOls. WiTh two moRE yEARs oF fOlLow-Up WE eStimaTe aNother 15 - 21 sUbjects wilL deVeLop chronic baCK pAin disabilIty. an increased nUmbEr of suBjEctS In the ChrOnicaLly disABled caTegory wouLd ADd to thE StatistICAl PoweR for
 disabling back problems o f at least  a th ree -mo nt h du rati on have a sign i fica ntly different fitness  leve lt hant he ir ag e-match e dc o ntr ol s.  Wi th tw o mor e y ears of  follow-up  we  e stimate anot h er  15 - 21 s ubj ects will de vel op chr on icb ack p ain  disa bility .  An in creased n um b er ofs ubjects i nthechronically disab l ed category would  add t ot he s tat ist ical power  f or
 disabling_back problems_of at least a_three-month duration_have_a significantly_different_fitness level than_their age-matched controls._With two more years_of follow-up we_estimate_another 15 - 21 subjects will develop chronic back pain disability. An increased number_of_subjects in_the_chronically_disabled category would add to_the statistical power for