This chicken-or-the-egg question has puzzled researchers for years. Patients with low back pain typically have more pain with physical activity. Studies suggest that they also score lower on measures of mental health. Which comes first in determining their physical performance? Do depression and anxiety cause pain in physical activity? Or does pain in physical activity create depression and anxiety?

Researchers recently looked at the performance of low back pain patients on a treadmill. How long could patients walk? And what made them stop? Half of the patients stopped walking because of pain. Though patients with poor mental health were more likely than others to stop walking because of pain, mental health actually didn't influence the number of minutes patients walked. Pain was more important to patients' physical performance. This suggests that poor mental health may be a result of having pain in physical activity, rather than a cause.

Certainly, this kind of question is best answered on a case-by-case basis. For many patients with low back pain, both physical and emotional issues must be addressed to get the best results from treatment.