Fig. 7From: Efficacy of pre-operative quadriceps strength training on knee-extensor strength before and shortly following total knee arthroplasty: protocol for a randomized, dose-response trial (The QUADX-1 trial)A hypothetical presentation of group changes in knee-extensor strength over the whole trial period. NB, control data are from the academic literature [11] and so are the healthy, age-matched, control data (age 66.8Â years (6.5 SD)) [7]Back to article page