Scarfe, AC, Li, F-X, Reddin, DB, and Bridge, MW. A new progression scale for common lower-limb rehabilitation tasks. J Strength Cond Res 24(x): 000-000, 2010-The treatment of most injuries tends to have similar goals: to minimize initial pain and swelling, restore full range of motion, and return to full strength. One of the key problems is the gap between the traditional rehabilitation modalities and progression to normal locomotive and athletic activities. Closed kinetic chain exercises are a common feature of rehabilitation programs, yet progression of these exercises in a rehabilitation setting has traditionally been based on anecdotal advice, and there is a shortage of empirical evidence. The aim of this study is to use ground reaction force measures to guide progression of closed kinetic chain rehabilitation exercises for active individuals recovering from lower extremity injury. Twenty-four injury-free participants carried out 10 different movements including jumps, squats, and locomotive tasks. Force data collected via a Kistler force platform were used to quantify peak vertical force (Fz), peak vertical force relative to body weight (Fz/BW), and rate of force development (RFD). A Vicon motion analysis system provided kinematic data. There were significant interactions of task and peak Fz, task and peak Fz/BW, and task and RFD. For all force measures, the majority of tasks were significantly different from one another. The effect of kinematic variability was evaluated using the Pearson Correlation coefficient. A clear progression of exercises was seen in both peak Fz and peak Fz/BW, whereas RFD measures showed 3 distinct groups. Combining the data from the measures leads to the grouping the exercises into early, mid, late, and final stages of rehabilitation. We suggest that practitioners use this ranking to prescribe appropriate exercises for particular stages of rehabilitation.