The legislation was an effort to curb childhood obesity and related health problems. But school boards and superintendent groups said the measure would require additional staff and facilities -- and would be too burdensome on many districts already facing budget pressure.
In a statement Thursday, McDonnell calls the measure an unfunded mandate that could cut into time for instruction in math, science, history and reading.
He says he agrees that exercise and physical activity are important. His wife -- first lady Maureen McDonnell -- has made exercise and preventive health care priorities. But the governor also argues that the problem of childhood obesity cannot be solved through legislation.