STUDY DESIGN: A longitudinal assessment of the association between pain-related fear and joint motions in 36 participants with subacute low back pain. OBJECTIVES: To determine how the psychologic construct of pain-related fear maps to motor behavior in standardized reaching tasks. SUMMARY OF BACKGROUND DATA: Pain-related fear is a significant predictor of avoidance behavior and occupational disability in individuals with low back pain. However, it is not currently known how pain-related fear maps to motor behavior. METHODS: Participants with an episode of subacute LBP were tested at 3, 6, and 12 weeks following pain onset. Participants performed reaching tasks at comfortable and fast-paced movement speeds to 3 targets (high, middle, low) located in a midsagittal plane. Three-dimensional joint motions of the thoracic spine, lumbar spine, and hip were recorded using an electromagnetic tracking device. Group differences in joint excursions were assessed using 2 groups (high pain-related fear, low pain-related fear) x 3 times (3, 6, 12 weeks) x 2 movement speeds (comfortable, fast paced) x 3 target heights (high, middle, low) MANOVAs. RESULTS: Individuals with high pain-related fear had smaller excursions of the lumbar spine for reaches to all targets at 3 and 6 weeks, but not at 12 weeks following pain onset. CONCLUSION: Individuals with high pain-related fear adopt alternative movement strategies and avoid motion of the lumbar spine when performing a common reaching movement. Identifying how pain-related fear maps to actual motor behavior (i.e., alternative movement strategies) is a crucial first step in determining how pain-related fear and motor behavior interact to promote or delay recovery from acute low back pain.