Smartphone-based real-life activity data for physical performance outcome in comparison to conventional subjective and objective outcome measures after degenerative lumbar spine surgery

•Smartphone-based activity data allows for continuous longitudinal physical performance assessment after lumbar spine surgery.•It captures both, a preoperative deterioration, and a postoperative improvement of patients' physical performance.•Although smartphone-based performance correlated with physical capacity/PROMs, daily activity decreased again postoperatively•This discrepancy indicates that smartphone-based performance may provide a more in-depth assessment of function over time.