In patients with low back pain (LBP), physical functioning may be negatively 
influenced by both expectations on pain and pain-related fear. It is unclear 
whether these factors influence both physical functioning in the laboratory as 
well as in daily life. The aim of this study was to test if a combination of 
persistent overprediction of pain and fear of movement predicts lab-based 
performance and whether these factors are relevant for predicting daily-life 
functioning. One hundred and twenty four patients with subacute LBP performed a 
laboratory-based performance test twice. Maximum voluntary contraction, pre-test 
pain expectations, perceived pain during testing and fear of movement were 
measured. Patients were classified as correct or incorrect predictors, based on 
differences between expected and perceived pain on the second attempt. Next, 
physical activity in daily life was measured with an accelerometer. In 
explaining physical functioning in the laboratory and in daily life an 
interaction effect between fear and pain prediction was observed. In 
overpredictors, fear was negatively associated with lab-based performance 
(beta=-0.48, p<0.01), and positively associated with daily-life functioning 
(beta=0.50, p<0.05). No significant association between fear and performance or 
daily-life functioning were found in correct predictors. In contrast to correct 
predictors, in overpredictors lab-based performance and daily-life functioning 
was additionally explained by fear of movement. Thus it appears that fear of 
movement is only predictive of performance in patients with LBP who 
simultaneously overpredict the consequences of movements in terms of 
painfulness.