Figure 1.

Singly housed, 18 months old BALB/c mice readily and consistently use slanted running wheels placed inside the cage in a tumor dependent manner. The mice were allowed to run 60 days before injection with 4T1 breast tumor cells, and an additional 30 days after tumor cell injection, at which time they were euthanized and tumors measured. A. Mice ran longer distances before tumor cell injection compared to after tumor cell injection, p = 0.0006. B. Mice that ran longer distances before tumor cell injection had decreased tumor mass measured at the time of euthanasia, Pearson’s r = -0.89, P = 0.0066, R² = 0.80. C. There was also a negative correlation between pre-tumor running distance and primary tumor mitotic index, Pearson’s r = -0.85, P = 0.034, R² = 0.72.